Technical Field

[0001] Embodiments relate generally to lighting devices, systems and methods using at least one light-emitting diode (LED) configured to emit blue-enriched light and/or at least one LED configured to emit blue-depleted light.

Background

[0002] It has been observed in recent studies that humans are more directly affected by the quality of light in their direct environment than was previously suspected.

[0003] Standard lighting could reduce a person’s signal for sleep, potentially reducing the quality of sleep. It is known that sleep deprivation can compromise a person’s general health and wellbeing. It can also alter social and emotional judgments and regulation. Specific occupational groups, such as shift workers and those working in safety-critical environments, may be at increased risk due to abnormal sleep and light exposure patterns.

[0004] It is desired to address or ameliorate one or more disadvantages or shortcomings associated with prior lighting devices or lighting systems, or to at least provide a useful alternative thereto.

[0005] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0006] Throughout this specification the word "comprise", or variations such as

"comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Summary

[0007] Some embodiments relate to a lighting device, including: a first lighting circuit including at least one first light emitting device that is configured to emit light in a wavelength range of about 430 nm to about 490 nm, with a melanopic to photopic (M/P) lux ratio of about 0.8 to about 1.0 and a colour rendering index of about 80 to about 99; a second lighting circuit including at least one second light emitting device that is configured to emit light that has a substantially reduced spectral power distribution across a wavelength range of about 430 nm to about 490 nm, with a melanopic to photopic (M/P) lux ratio of about 0.3 to about 0.4 and a colour rendering index of about 80 to about 99; and a switching unit to selectively switch power to the first lighting circuit and to the second lighting circuit.

[0008] Some embodiments relate to a lighting device, including: a lighting circuit including at least one light emitting device that is configured to emit light in a wavelength range of about 430 nm to about 490 nm, with a melanopic to photopic (M/P) lux ratio of about 0.8 to about 1.0 and a colour rendering index of about 80 to about 99.

[0009] The M/P lux ratio may between about 0.9 and about 1.0, for example. The correlated colour temperature (CCT) of the at least one light emitting device is about 3900K to about 4500K, optionally about 3950 to about 4300K, optionally about 4000 to 4200 Kelvin. [0010] Some embodiments relate to a lighting device, including: a lighting circuit including at least one light emitting device that is configured to emit light that has a substantially reduced spectral power distribution across a wavelength range of about 430 nm to about 490 nm, with a melanopic to photopic (M/P) lux ratio of about 0.3 to about 0.4 and a colour rendering index of about 80 to about 99.

[0011] A correlated colour temperature (CCT) of the at least one light emitting device may be about 2000K to about 2700K, optionally about 2200K to about 2600K, optionally about 2350K to about 2500K. The M/P lux ratio may be between about 0.35 and about 0.39.

[0012] Some embodiments relate to a luminaire including multiple lighting devices as described herein.

[0013] Some embodiments relate to a lighting system including multiple lighting devices as described herein. The lighting system may further comprise a controller to control power to each of the multiple lighting devices. The controller may control power to each of the multiple lighting devices based on a switching parameter.

[0014] Some embodiments relate to a method of affecting alertness in a human, including: switching or transitioning power from a power supply between a first lighting and a second lighting circuit, wherein the first lighting circuit includes at least one first light emitting device that is configured to emit light in a wavelength range of about 430 nm to about 490 nm, with a melanopic to photopic (M/P) lux ratio of about 0.8 to about 1.0 and a colour rendering index of about 80 to about 99, and wherein the second lighting circuit includes at least one second light emitting device that is configured to emit light that has a substantially reduced spectral power distribution across a wavelength range of about 430 nm to about 490 nm, with a melanopic to photopic (M/P) lux ratio of about 0.3 to about 0.4 and a colour rendering index of about 80 to about 99.

[0015] The switching or transitioning power may include switching or transitioning power from the first lighting device to the second lighting device.

[0016] The switching or transitioning power may include switching or transitioning power from the second lighting device to the first lighting device.

[0017] The switching or transitioning may be performed in response to determining that a switching condition is satisfied. The switching or transitioning may be performed in response to a control signal received from a controller. The controller may be co located with the first lighting device and the second lighting device or remote from the first lighting device and the second lighting device.

[0018] Some embodiments relate to a lighting system including two channel LED arrays and circuit boards where the LED colour spectrum wavelengths on one channel are blue-depleted with a melanopic-to-photopic lux ratio (M/P) less than or equal to 0.35, a nominal correlated colour temperature (CCT) of 2400K (Kelvin) and a colour rendering index (CRI) of 89 or higher, and the LED colour spectrum wavelength on the other channel are blue-enriched with a melanopic-to-photopic lux ratio (M/P) greater than or equal to 0.90, a nominal correlated colour temperature (CCT) of 4200K (Kelvin) and a colour rendering index (CRI) of 89 or higher.

[0019] The LED arrays and circuit boards are coupled with controls and allow switching and transitioning between blue-enriched and blue-depleted according to norms for circadian wellbeing and/or to individually prescribed levels, whilst maintaining a colour rendering index of (CRI) of 89 or higher.

Brief Description of the Drawings [0020] Embodiments are described in further detail below, by way of example, with reference to the drawings, in which:

[0021] Figure 1 is a schematic diagram of a lighting device according to some embodiments;

[0022] Figure 2 is a schematic diagram of a lighting device according to some embodiments;

[0023] Figure 3 is a schematic diagram of a lighting device according to some embodiments;

[0024] Figure 4 is a schematic diagram of a lighting device according to some embodiments;

[0025] Figure 5 is a block diagram of a lighting system employing one or more of the lighting devices of any of Figures 1 to 4;

[0026] Figure 6 is a flow chart of a method of operation of a lighting device or lighting system according to some embodiments; and

[0027] Figure 7 is a graph of predicted melatonin suppression as a function of photopic illuminance and melanopic illuminance for evening light exposure.

Detailed Description

[0028] Embodiments relate generally to lighting devices, systems and methods using at least one light-emitting diode (LED) configured to emit blue-enriched light and at least one LED configured to emit blue-depleted light. Some embodiments may use only blue-enriched LEDs, while other embodiments may use only blue-depleted LEDs.

LEDs forming part of embodiments described herein are generally phosphor-based LEDs. [0029] Modern white light sources have typically been rich sources of blue-laden light and, recently, the biological sensitivity to blue light has been found to be greater than expected. In view of this, the challenge is to artificially illuminate our environments in a pleasing and efficient manner, with minimal distortion to our health and natural circadian cycles.

[0030] The inventors have found that the Melanopic/Photopic ratio (M/P ratio) of a light source plays a fundamental role in delivering lighting-related benefits, and that the amount of blue light in a light source has a significant effect on human internal clocks. For example, the amount of blue light in a light source determines the effect of that light on a human internal 24-hour circadian clock.

[0031] Normal illumination is discussed in terms of photopic lux, which is the amount of light registered on the image-forming cone receptors of the human retina. The retina also registers light on non-visual cells called ‘intrinsically photosensitive retinal ganglion cells’ (ipRGCs). Melanopic lux is a term used to describe the portion of the illumination that the ipRGCs register or ‘see’.

[0032] Melanopic/Photopic lux ratio, or M/P ratio, is a description of the amount of blue light stimulus present in the normal photopic illumination. References to M/P ratio numbers described in some embodiments may be found using calculation method 3 (IWBI) as discussed and summarised in Table 1 within the article “M/P ratios - Can we agree on how to calculate them?” published by the Illuminating Engineering Society on 27 November 2019 and authored by Naomi Miller et al (accessible at https://www.ies.org/t1res/m-p-ratios-can-we-agree-on-how-to- ealculate-them/), the contents of which is hereby incorporated herein by reference. Equivalent M/P ratio numbers may be found using multiplying factors or other mathematical functions/methods such as the multiplying factors in table 2 within the aforementioned article by Naomi Miller et al.

[0033] For purposes of the present disclosure, the M/P ratio values referenced and claimed herein are calculated using method 3 (IWBI or WELL Building Standard v2), which may also be called the LUCAS method. This method broadly involves the following steps:

• Take measured SPD (spectral power distribution) values for a light source received from a manufacturer’s laboratory test or measure the light incident on an observer’s eye using a spectrometer.

• Multiply the value of the SPD at each wavelength by the value at the same wavelength of the melanopic weighting function normalized so that its area under the curve equals 1 when evaluating the equal-energy spectrum. Sum the values to get melanopic radiant watts.

• Multiply the value of the SPD at each wavelength by the value at the same wavelength of the photopic weighting function normalized so that its area under the curve when evaluating an equal-energy spectrum is 1. Sum the values to get photopic radiant watts.

• Divide the summed melanopic radiant watts by the summed photopic radiant watts. This gives the M/P ratio for method 3.

[0034] For purposes of the present disclosure, the R9 values referenced herein refer to a value determined by a Colour Rendering Index test for R9 (red).

[0035] Melanopic illuminance is now thought by the inventors to be a key predictor of melatonin suppression. For example, a light source with M/P lux ratio of -0.4 is predicted to have low circadian impact below ~43 lux. A light source with M/P lux ratio of -0.9 is predicted to have low circadian impact below ~20 lux and to have high circadian impact above -104 lux.

[0036] Embodiments employing this discovery may include a range of lighting- related products, including panel lights, downlights, extrusion lights, multi-purpose lights, and Interior and Exterior Violence-prone lights. [0037] For example, light at night may decrease sleep quality and suppress the ‘sleep- hormone’ melatonin by more than 50%. Embodiments described herein may be used in a neonatal ward, for example to help long-term visitors experience ‘normal’ day/night light (needed to maintain a healthy body clock), and to also encourage feelings of calm. Lighting system embodiments described herein could also benefit patients with their rest and recovery, promoting sleep and alertness as required. Indeed, it is estimated that healthy lighting can reduce hospital stays by up to 15%.

[0038] Sleep and body clock problems due to unhealthy light can make humans more sensitive to negative events and increase our risk of depression. Light actually has direct mood-elevating effects, and ‘light therapy’ has even been shown to help treat depression. It has also been shown that dynamic lighting interventions can potentially reduce the length of psychiatric hospital stays, and reduce agitation and improve cooperation in dementia patients. For these reasons in particular, embodiments described herein may be used to promote healthy sleep in correctional facilities and thus improve mood and mental health among inmates.

[0039] Poor lighting can lead to poor health outcomes for any person within any industry. Chronic body clock issues can increase the risk of diabetes, heart disease, and cancer. In comparison to day workers, shift workers have 1.5 times the risk of cardiovascular disease.

[0040] Some embodiments relate to a blue-enriched light source that has an alerting benefit. Such a light source may be particularly important for shift workers and those performing tasks that require high levels of concentration, including educational facilities. Such blue-enriched light can improve the quality of work performed, and positively impact on OH&S issues, workplace accidents, and commuting to or from work.

[0041] Embodiments also relate to modified white light sources with high colour rendering, blue-depleted illumination. Such embodiments can deliver a warm appearance and a low M/P lux ratio that is highly useful for dedicated illumination in preparation for rest, allowing for improved length and quality of restorative sleep.

[0042] Some embodiments include luminaires or lighting systems that include a combination of both blue-enriched and blue-depleted LED light devices (or chips).

Such embodiments may allow for transitions between the blue-enriched and blue- depleted lighting. Such embodiments may be particularly useful for driving optimal sleep cycles within permanently occupied spaces, such as those that exist in hospitality, military, healthcare, aged-care, and correctional facilities, for example.

[0043] Figure 1 is a schematic diagram of an example lighting device 100, which can be used as part of a lighting apparatus and system as described herein.

[0044] The lighting device (100) includes a blue enriched light element (105) that comprises blue enriched LEDs (108). The blue enriched light element (105) is a logical grouping of the blue enriched LEDs (108). Blue enriched LEDs (108) may comprise a combination of blue and cyan LED dies positioned adjacent to each other. Each blue- enriched LED (108) may include a higher number of blue dies than cyan dies. Suitable phosphor substances may be used to form the LEDs (108) or light element (105). In some embodiments, blue enriched light element (105) also comprises a physical grouping, substrate or entity for mounting the blue enriched LEDs (108) separately from other LEDs.

[0045] In some embodiments, blue enriched light element (105) may comprise the physical board or carrier which blue enriched LEDs (108) are mounted on, where the physical board or carrier is a substrate (135). Blue enriched LEDs (108) comprise one or more (modified) white light LEDs which are blue enriched. LEDs (108) are modified white light LEDs configured to emit light that has an increased spectral power distribution across wavelengths approximately in the range of 430-490 nm corresponding substantially to blue light. The LEDs (108) are designed so that light emitted from light-emitting portions has a relatively high melanopic light content. Specifically the emitted light has a melanopic to photopic (M/P) lux ratio of between about 0.8 and about 1.0. The emitted light is produced with a CRI between about 80 and about 99. The emitted light is produced at a CCT of nominally at about 4000 to 4200 Kelvin. The emitted blue enriched light may be produced at an R9 value of 90 or higher, for example.

[0046] The lighting device (100) further includes a blue depleted light element (106) that comprises blue depleted LEDs (109). The blue depleted light element (106) is a logical grouping of the blue depleted LEDs (109). In some embodiments, an LED such as that made by Luminus Devices Inc. under product code MP-3030-210H-22-90 or a similarly configured LED can be used as the blue depleted LED (109). Suitable phosphor substances may be used to form the LEDs (109) or light element (106). In some embodiments, blue depleted light element (106) also comprises a physical grouping, substrate or entity for mounting the blue depleted LEDs (109) separately from other LEDs. In other embodiments, for example as shown in Figure 4, blue- enriched LEDs, blue-depleted LEDs, and/or other LEDs can be mounted on the same substrate and can be physically interspersed with each other.

[0047] In some embodiments, blue depleted light element (106) may comprise the physical board or carrier which blue depleted LEDs (109) are mounted on, where the physical board or carrier is a substrate (136). Blue depleted LEDs (109) comprise one or more LEDs which are blue depleted. LEDs (109) are modified white light LEDs that are configured to emit light that has low light emissions in a wavelength approximately in the range of 430-490 nm (corresponding to blue light wavelengths). The LEDs (109) are designed so that light emitted from light-emitting portions has a relatively low melanopic light content. This means that the emitted light of the blue-depleted LEDs may have between 50% and 90% less spectral energy in a wavelength range (e.g. 430- 490 nm) corresponding to blue light when compared with a white light LED having a relatively typical spectral power distribution across the visible light range. Specifically, the emitted blue depleted light has a melanopic to photopic (M/P) lux ratio of between about 0.3 and about 0.4. The emitted blue depleted light is produced with a CRI between about 80 and about 99. The emitted blue depleted light is produced at a CCT of nominally about 2400 Kelvin, although this can vary between about 2000 K and 2700 K. The emitted blue depleted light may be produced at an R9 value of 50 or higher, for example.

[0048] A power supply (122) may supply power from mains power, battery power or another power source.

[0049] A power supply connector (120) is an interface for the transfer of power from the power supply (122) to the lighting device (100). Power supply (122) may include a mains supply at 50/60 Hz, for example.

[0050] The power supply (122) delivers power via the power supply connector (120) interface through to power supply connection line (125) and power supply connection line (124) which transmit power to the blue enriched light element (105) and blue depleted light element (106) respectively. Power supply connection lines (124) and (125) also comprise return neutral and ground lines. Power element (128) comprises regulators, transformers, adapters, rectifiers or any element used to modify the power delivered from the power supply (122) to blue enriched light element (105) and blue depleted light element (106).

[0051] A control input (112) comprises signal sources for the purpose of lighting control. The control input (112) in some embodiments comprise of signal sources from two-way switching, gradual lighting transitions, manual, automated or any other lighting control systems.

[0052] A controller (110) may comprise of a circuit or processor. The controller (110) receives signal sources from the control input (112) and sends signals via a first signal line (115) and a second signal line (114) to control the power delivered to blue enriched light element (105) and blue depleted light element (106) respectively.

[0053] In some embodiments, the lighting device (100) may typically be housed within a light fixture body, to create a light fixture (140). The light fixture may include a luminaire housing. The housing may be constructed to standard AS/NZS 60598, for example. Light fixtures may comprise one or more of panel lights, downlights, extrusion lights, multi-purpose lights, and Interior and Exterior Violence-prone lights, for example.

[0054] In some embodiments, the lighting device (100) may form part of a display screen or projector. In some embodiments, the lighting device may be or form part of a mobile computing device, tablet computing device or a television or computer monitor, for example.

[0055] Figure 2 is a schematic diagram of an example lighting device (200) which can be used as part of lighting apparatus or system described herein. The lighting device (200) includes a controller (110) and a blue enriched light element (105) that comprises blue enriched LEDs (108). The blue enriched light element (105) is a logical grouping of the blue enriched LEDs (108). In some embodiments, blue enriched light element (105) also comprises a physical grouping or entity for mounting the blue enriched LEDs (108).

[0056] In some embodiments, blue enriched light element (105) may comprise the physical board or carrier (e.g. printed circuit board (PCB)) which blue enriched LEDs (108) are mounted on, where the physical board or carrier acts as a substrate (135).

Blue enriched LEDs (108) comprise one or more LEDs which are blue enriched. LEDs (108) are modified white light LEDs configured to emit light that has an increased spectral power distribution across wavelengths approximately in the range of 430-490 nm, for example. The LEDs (108) are designed so that light emitted from light-emitting portions has a relatively high melanopic light content. Specifically the emitted light has a melanopic to photopic (M/P) lux ratio of between about 0.8 and about 1.0.

Optionally, the M/P lux ratio is about 0.85 to about 1.0. Optionally, the M/P lux ratio is about 0.9 to about 1.0. Optionally, the M P lux ratio is about 0.9 to about 0.95. Optionally, the M/P lux ratio is about 0.92 to about 0.98. The emitted light is produced with a CRI between about 80 and about 99. Optionally, the CRI is between about 85 and 95. Optionally, the CRI is between about 89 and 95. The emitted light is produced at a CCT of nominally about 3900K to about 4500K, optionally about 3950 to about 4300K, optionally about 4000 to 4200 Kelvin. The emitted blue enriched light may be produced at an R9 value of 90 or higher, for example.

[0057] In Figure 2, a power supply connector (120) is an interface for the transfer of power from the power supply (122) to the blue enriched lighting device (200).

[0058] In Figure 2, the power supply (122) delivers power via the power supply connector (120) interface through to power supply connection line (125) which transmits power to the blue enriched light element (105). Power supply connection line (125) also comprises return neutral and ground lines. Power element (128) comprises regulators, transformers, adapters, rectifiers or any element used to modify the voltage and/or current delivered from the power supply (122) to blue enriched light element (105).

[0059] A control input (112) comprises signal sources for the purpose of lighting control. The control input (112) in some embodiments comprise signal sources from two-way switching, gradual lighting transitions, manual, automated or any other lighting control systems.

[0060] The controller (110) may comprise a circuit or processor. The controller (110) receives signal sources from the control input (112) and sends signals via line (115) to control the power delivered to blue enriched light element (105).

[0061] In some embodiments, the blue enriched lighting device (200) may typically be housed within a light fixture body (140), to create a light fixture. Light fixtures may comprise panel lights, downlights, extrusion lights, multi-purpose lights, and interior and exterior violence-prone lights.

[0062] In some embodiments, the blue enriched lighting device (200) may form part of a display screen, touch screen or projector. In some embodiments, this may be or include a mobile computing device, tablet device or a monitor, for example. [0063] Figure 3 is a schematic diagram of an example lighting device (300) which can be used as part of lighting apparatus or system described herein. The lighting device (300) includes a blue depleted light element (106) that comprises blue depleted LEDs (109). The blue depleted light element (106) is a logical grouping of the blue depleted LEDs (109). In some embodiments, blue depleted light element (106) also comprises a physical grouping or entity for mounting the blue depleted LEDs (109).

[0064] In some embodiments, blue depleted light element (106) may comprise the physical board or carrier (e.g. printed circuit board (PCB)) which blue depleted LEDs (109) are mounted on, where the physical board or carrier acts as a substrate (136).

Blue depleted LEDs (109) comprise one or more modified white light LEDs which are blue depleted. LEDs (109) are configured to emit light that has a substantially reduced spectral power distribution of light in wavelengths approximately in the range of 430- 490 nm. The LEDs (109) are designed so that light emitted from light-emitting portions has a relatively low melanopic light content. Specifically, the emitted blue depleted light has a melanopic to photopic (M/P) lux ratio of between about 0.3 and about 0.4. Optionally, the M/P lux ratio is between about 0.3 to about 0.35, optionally between about 0.35 and about 0.39, optionally about 0.38. The emitted blue depleted light is produced with a CRI between about 80 and about 99. Optionally, the CRI is between about 85 and 95. Optionally, the CRI is between about 89 and 95. The emitted blue depleted light is produced at a CCT of nominally about 2000K to about 2700K, optionally about 2300K to about 2600K, optionally about 2350K to about 2500K. In some embodiments, the emitted blue depleted light is produced at a CCT of about 2400 Kelvin. The emitted blue depleted light may be produced at an R9 value of 50 or higher, for example.

[0065] In Figure 3, a power supply connector (120) is an interface for the transfer of power from the power supply (122) to the blue depleted lighting device (300).

[0066] In Figure 3, the power supply (122) delivers power via the power supply connector (120) interface through to power supply connection line (124) which transmits power to the blue depleted light element (104). Power supply connection line (124) also comprises return neutral and ground lines. Power element (128) comprises regulators, transformers, adapters, rectifiers or any element used to modify the power delivered from the power supply (122) to blue depleted light element (106).

[0067] A control input (112) comprises signal sources for the purpose of lighting control. The control input (112) in some embodiments comprise signal sources from two-way switching, gradual lighting transitions, manual, automated or any other lighting control systems.

[0068] The controller (110) may comprise a circuit or processor. The controller (110) receives signal sources from the control input (112) and sends signals via control signal line (114) to control the power delivered to blue depleted light element (106).

[0069] In some embodiments, the blue depleted lighting device (300) may typically be housed within a light fixture body to create a light fixture. Light fixtures may comprise one or more of panel lights, downlights, extrusion lights, multi-purpose lights, and interior and exterior violence-prone lights, for example.

[0070] In some embodiments, the blue depleted lighting device (300) may form part of a display screen or projector. In some embodiments, the lighting device may be or form part of a mobile computing device, tablet computing device or a television or computer monitor, for example.

[0071] The table below shows parameter ranges for emitted light for devices (100,

200 and 300) according to some embodiments. LEDs with higher blue content at relatively warmer colour temperatures than currently readily available, nominally 4200k or warmer.

[0072] Figure 4 is a schematic diagram of a lighting device (400) according to some embodiments. The lighting device (400) has blue-depleted LEDs and blue-enriched LEDs combined on a single PCB (405) or other substrate. The blue-depleted LEDs and blue-enriched LEDs are controllable as two separate LED channels. The lighting device (400) is otherwise similar to lighting device (100) in that it relies on a power supply (122) and receives a control input (112) to controller (110) in order to provide power at a certain voltage/current level to each separate array of LEDs.

[0073] Figure 4 shows two alternative arrangements of the two logically separate (i.e. separately controlled) channels of blue-enriched and blue-depleted LED arrays. In one arrangement, the LEDs are spaced in a linear array on substrate (405), while in another arrangement, the LEDs are spaced from each other in a generally circular pattern around a central point. In each case, blue-enriched LEDs can be spatially interspersed with blue-depleted LEDs. This may allow a transition from one LED channel to the other to be visually smooth, without being visibly noticeable to a person. Other geometric arrangements of LEDs may be achieved on substrate (405) to suit particular lighting requirements.

[0074] Some embodiments relate to two channel LED arrays and circuit boards where the LED colour spectrum wavelengths on one channel are blue-depleted with a melanopic-to-photopic lux ratio (M/P) less than or equal to 0.35, a nominal correlated colour temperature (CCT) of 2400K (Kelvin) and a colour rendering index (CRT) of 89 or higher, and the LED colour spectrum wavelength on the other channel are blue- enriched with a melanopic-to-photopic lux ratio (M/P) greater than or equal to 0.90, a nominal correlated colour temperature (CCT) of 4200K (Kelvin) and a colour rendering index (CRI) of 89 or higher. In some embodiments, the blue-depleted channel has an R9 value of 50 or higher, and the blue-enriched channel has an R9 value of 90 or higher. These LED arrays and circuit boards are coupled with controls and allow switching and transitioning between blue-enriched and blue-depleted according to norms for circadian wellbeing and/or to individually prescribed levels, whilst maintaining a colour rendering index of (CRI) of 89 or higher. Such LED arrays may form part of a lighting device or a lighting system as described herein.

[0075] Some embodiments relate to a substrate carrying one or more LED chips, forming part of a system that is programmed to deliver the alertness- or sleep- promoting light at predetermined times or under predetermined conditions. Embodiments may, for example, include lighting devices or systems that allow for transitions between the 0.30-1.0 M/P ratio modes of illumination (from 2000-4500K CCT), CRI of 80-99 (e.g. 89).

[0076] Such embodiments and other embodiments described herein may be useful for promotion of optimal or improved sleep cycles of inhabitants of built environments.

For example, such embodiments and other embodiments described herein may be useful for promotion of optimal or improved sleep cycles of inhabitants within permanently occupied built environments, such as those that exist in hospitality, military, healthcare, aged-care, and correctional facilities.

[0077] Some embodiments relate to a LED module including two independent channels capable of achieving the above blue-enriched and blue-depleted parameters either by simple switch control or advanced lighting control systems. In some embodiments, more than two channels may be used.

[0078] Embodiments of described LED arrays, circuit boards and lighting devices can be coupled with simple 2-circuit light switching and/or conventional building or lighting control systems, for example. Embodiments may employ switching methods that allow gradual transitioning over a predetermined time period (e.g. over 20 minutes to 2 hours) between blue enriched light and blue depleted light modes to affect alertness and/or human circadian rhythms. Embodiments may be controlled to individually prescribe the lighting levels and colour temperature while maintaining a CRI of 89 or greater for multiple separate spaces within a built environment.

[0079] Figure 5 depicts, in some embodiments, a lighting system (520) that comprises a system controller (510) which controls a plurality of lighting devices (100, 200, 300, 400).

[0080] In some embodiments, an overarching environment control system (500) may comprise one or more lighting systems (520) controlled by a master controller (535), whereby the master controller (535) interfaces to the system controller (510) within the system (520).

[0081] The plurality of lighting devices (100, 200, 300, 400) are powered by one or more power supplies (112).

[0082] Figure 6 is a flowchart of a method 600 of operation of the controller (110, 510, 535) of Figure 1 to control the lighting device (100). In performing method 600, the controller (110) monitors a switching parameter at 605. The switching parameter is stored in or accessible to the controller (110, 520, 535). In some embodiments, the controller (110, 510, 535) may be the inner components of a light switch, and the switching parameter being monitored in 605 is the switching of contacts which may be mechanically controlled by pressing a push button. In other embodiments, the switching parameter may include a time of day or a logical condition based on input received from another sensor, such as a motion sensor, for example.

[0083] In various embodiments, the system controller (510) or the master controller (535) may monitor the switching parameter as part of the functions of an environment control system that the lighting system (520) or lighting devices (100, 200, 300, 400) form a part of. For example, master controller (535) may control various lighting and non-lighting devices within a building, a home, a craft (e.g. boat or plane) or another built environment, and the switching of the lighting system (520) or the lighting devices (100, 200, 300, 400) may be automatically controlled according to a time of day or another criterion or parameter. In this way, master controller (535) may automatically control switching on or off multiple or individual ones of the lighting devices (100, 200, 300, 400) in different areas of the built environment or may control the transition of multiple or individual ones of lighting devices (100, 200, 300, 400) from one state of illumination (e.g. bright or dim) to another state of illumination (e.g. dim or bright).

[0084] Upon a switching parameter detection at 605, the controller (110, 510, 535) determines whether a switching condition is satisfied at 610. If the switching condition is not satisfied, the controller (110, 510, 535) will resume monitoring switching parameter at 605. If the controller (110, 510, 535) determines that a switching condition is satisfied, the controller (110, 510, 535) transmits a control signal to lighting device (100, 200, 300, 400) or lighting system (520) at 620, and resumes monitoring the (or another) switching parameter at 605.

[0085] Figure 7 is a graph of predicted melatonin suppression as a function of photopic illuminance and melanopic illuminance for evening light exposure. Black laterally extending contour curves correspond to different levels of melatonin suppression, ranging from 20% to 70% suppression. The magenta curves expanding out from the zero points of the graph axes correspond to different melanopic-to-photopic (M:P) ratios, ranging from 0.2 to 1.0.

[0086] Various embodiments are described and disclosed herein. One or more features, functions, characteristics or aspects of one or more embodiments may be combined with one or more features, functions, characteristics or aspects of one or more other embodiments to give rise to further embodiments. The embodiments described and disclosed herein are therefore to be understood as being presented by way of example. Embodiments of the present disclosure are intended to encompass all workable combinations of features of described embodiments.