Abstract: Systems and methods that provide improved control of addressable lighting fixtures. Individual lighting units have assigned schedules defining the power levels for the unit at various times of the day. Adjustments to a scheduled level for each unit may be made depending on predefined exceptions, ambient daylight, conservation commands, override instructions, and boost signals. Individual occupants of the building are associated with sets of individual lighting units. An override command received by the system and associated with a particular individual occupant is applied to the individual lighting units with which the individual occupant is associated.

Abstract: The invention relates to a current determination apparatus for determining an operational driving current for driving a light source of a group of light sources. A same color shift function defining a light color shift depending on a driving current can be provided for all light sources of the group. An operational driving current is determined based on the color shift function such that the light color (43) of the light source of the group of light sources is shifted from a nominal color, which may be specific for each light source, to a light color (45) within a target color window (41). Since for the different light sources the same color shift function can be used, a determination of individual operational driving currents such that the light sources of the group emit light having substantially the same color can be simplified.

Abstract: A method of configuring an LED driver is disclosed. The LED driver being arranged to provide a supply current to an LED fixture comprising a plurality of LEDs. The method comprises: identifying the LED fixture (LF), sending via a communication network (NTW) a configuration request to a configuration database (DB), receiving configuration data from the configuration database; and configuring the LED driver (LPS) according to the configuration data.

Abstract: An LED lighting system is provided for connection to a variable power source providing input power, the LED lighting system having at least one power analyzing and processing circuitry connecting to the variable power source, and being configured to identify one or more characteristics of the input power, where the characteristics are selected from amplitude, frequency and pulse width of the input power, compare one or more of the characteristics of the input power to preset control criteria either in hardware or software or both to yield a comparison result, and then control the current control circuitry according to the comparison result.

Abstract: A sensing device transmits wireless signals when an error between at least one sampled parameter value and at least one predicted parameter value is too great, such that the sensing device transmits wireless signals to a load control device using a variable transmission rate that is dependent upon the amount of change in a value of the parameter. The sensing device uses the one or more estimators to determine the predicted parameter value, and may transmit the estimators to the load control device if the error is too great. The load control device uses the estimators to determine at least one estimated parameter value and controls the electrical load in response to the estimated parameter value. The sensing device may comprise, for example, a daylight sensor for measuring a total light intensity in the space around the sensor or a temperature sensor for measuring a temperature around the sensor.

Abstract: A solid-state lighting system comprises a plurality of light-emitting devices (e.g., light-emitting diodes) and an alternating current to direct current (AC-DC) converter that converts AC power to DC power for powering the plurality of light-emitting devices. The AC-DC converter is configured to perform AC-DC conversion directly, without the need for or use of a bridge rectifier or step-down transformer. According to one aspect of the invention, the light-emitting devices of the solid-state lighting system are autonomous and individually powered by a plurality of DC power supplies generated from the DC power produced by the AC-DC converter. According to another aspect, a plurality of phase-offset dimmer control signals are generated based on waveform distortions in a dimming signal produced by a conventional dimmer switch. The phase-offset dimmer control signals are used to individually control the dimming of the light-emitting devices.

Abstract: An LED drive method is disclosed. In this way, the LED drive method allows not only the reference voltage to be periodically updated on the basis of the feedback drive voltages but also the drive voltage control signal to be generated using the updated reference voltage, in order to adjust the LED drive voltage applied to the LED array. Therefore, the LED drive circuit is hardly affected by the external environmental noise.

Abstract: Features of the invention are related to drive circuits that provide both power factor correction and voltage conversion in a single circuit and in some implementations drive an LED array. This single stage converter uses a buck-boost topology and can operate LED arrays that have DC voltages above or below the AC line voltage. An output side filter and bulk energy storage device is placed at the output of the circuit. Bulk energy storage can be provided by an inductor, a capacitor, or a combination of an inductor and a capacitor. The output side filtering can be provided by a capacitor or a capacitor and an inductor. The circuit also includes a switch and a switch control device for controlling the switch to provide power factor correction.

Abstract: A plant illumination apparatus includes a light source module including a first light source and a second light source generating lights having different wavelengths, an environment-detecting module detecting an external environment to obtain a real-time environment parameter, and a control module connected to the light source module and the environment-detecting module. The control module includes a processor unit and a storage unit storing a database of plant growing environment parameters. The processor unit loads at least one preset growing environment parameter corresponding to a plant growth timing from the database of plant growing environment parameters, and compares the preset growing environment parameter with the real-time environment parameter to output at least one comparison result. The processor unit adjusts the first light source and the second light source according to the comparison result, so that an adjusted environment parameter matches the preset growing environment parameter.

Abstract: The present invention relates to a hybrid multi-output power supply and regulation method thereof. In one embodiment, a power supply includes: a driving circuit that generates an error signal based on an expected driving voltage, the expected driving voltage being determined by an LED load driving current, and where the driving circuit regulates the driving current to be substantially constant and consistent with an expected driving current; a first stage voltage regulator receiving an input voltage and the error signal, and generating a first regulation voltage consistent with the expected driving voltage, where the first regulation voltage supplies power to the driving circuit, and provides driving voltage for the LED load, and where the first regulation voltage provides sufficient expected driving current; and a second stage voltage regulator that receives the first regulation voltage, and generates a substantially constant second regulation voltage to supply power to a first load.

Abstract: A lighting apparatus (L) includes: a light source section that includes two or more kinds of plural LEDs having different emission colors as light sources; a storage section that stores light color characteristic information that indicates the relation between a light color of an illumination light that is generable by the light source section and an output of each LED; a transmission section through which a light color control command for designating the light color of the illumination light is input; and a control section that converts the light color control command into output information of each LED on the basis of the light color characteristic information, and controls an output level of each LED on the basis of the output information.

Abstract: Systems and methods of variably controlling a driver signal to a light emitting device located proximate to a burner assembly of an appliance are provided. The driver signal can be adjusted based on a signal indicative of a temperature in a region proximate the light emitting device. The signal indicative of a temperature of the burner assembly temperature can be generated by a temperature senor or the signal can be based on an anticipated temperature profile of the burner assembly. The driver signal can be adjusted based on the signal indicative of the temperature of the burner assembly temperature using pulse width modulation.

Abstract: A method for mixing light of LEDs includes following steps: Firstly, a substrate with a red light LED, a green light LED and a blue light LED arranged thereon is provided. Secondly, a power source for supplying power to the red light LED, the green light LED and the blue light LED is provided. Thirdly, a temperature variation ?T1 of the red light LED caused by the power source, a temperature variation ?T2 of the green light LED caused by the power source, a temperature variation ?T3 of the blue light LED caused by the power source are calculated. And finally, input currents applied to the red light LED, the green light LED and the blue light LED are adjusted according to the temperature variations ?T1, ?T2 and ?T3. A lighting device using the method is also provided.

Abstract: Polychromatic light sources of white light are composed of at least two different coloured emitters, such as groups of light-emitting diodes (LEDs). Disclosed are the spectral power distributions and relative partial radiant fluxes of the coloured emitters that allow controlling the colour saturating ability of the generated light, namely, the ability to render colours with increased saturation and the ability to render colours with decreased saturation. Also disclosed is a method for dynamical tailoring the colour saturating ability of the generated light.

Abstract: In embodiments of the present invention, a method and system is provided for designing improved intelligent, LED-based lighting systems. The LED based lighting systems may include fixtures with one or more of rotatable LED light bars, integrated sensors, onboard intelligence to receive signals from the LED light bars and control the LED light bars, and a mesh network connectivity to other fixtures.

Abstract: A semiconductor apparatus includes an input terminal to which an input voltage is applied; an output terminal at which an output voltage is obtained; a power supply circuit unit configured to generate the output voltage from the input voltage, the output voltage having a value corresponding to a duty cycle of a voltage setting signal that is externally applied to the semiconductor apparatus; and a determination circuit unit determining whether the voltage setting signal has a predetermined signal level for the duration of a first predetermined time or longer. The determination circuit unit activates the power supply circuit unit when the voltage setting signal does not have the predetermined signal level for the duration of the first predetermined time or longer. The power supply circuit unit is deactivated when the voltage setting signal has the predetermined signal level for the duration of the first predetermined time or longer.

Abstract: A lighting device capable of generating warm or neutral white light using blue light-emitting diodes (“LEDs”), red LEDs, and/or luminescent material that responds to blue LED emission is disclosed. The lighting device includes multiple first solid-state light-emitting structures (“SLSs”), second SLSs, and balancing resistor element. The first SLS such as a string of blue LED dies connected in series is able to convert electrical energy to blue optical light, which is partially turned into longer wavelength emission by the luminescent material. The second SLS such as a red LED die is configured to convert electrical energy to red optical light, wherein the second SLSs are connected in series. While the first SLSs and second SLSs are coupled in parallel, the balancing resistor element provides load balance for current redistribution between the first and second SLSs in response to fluctuation of operating temperature.

Abstract: A lighting circuit, in particular for a motor vehicle light, comprises at least one light source, particularly of the LED type, defined by a first voltage selection, a first selection circuit to identify said first voltage selection, at least one light source, particularly of the LED type, defined by a second voltage selection, and a second selection circuit to identify said second voltage selection. An electronic control unit configured to detect said first and second voltage selection of the light source, and to regulate the driving current absorbed by the light source defined by the lower voltage selection, so that said driving current follows with a constant ratio the trend of the driving current absorbed by the light source defined by the higher voltage selection, the latter being taken as reference.

Abstract: A system for automatically adjusting light intensity of a lighting fixture having multiple emitters, includes a power supply for supplying at least one current source to multiple emitters, at least one first emitter capable of emitting light of a first wavelength, at least one second emitter capable of emitting light of a second wavelength and a luminous intensity adjusting circuit for adjusting light intensity of the at least one first emitter. Particularly, the luminous intensity adjusting circuit stabilizes a first current distributed from a feeding current of the at least one current source and the multiple emitters collectively emit light at a predefined variable light-intensity.

Abstract: An illumination light communication device includes a light source unit including light emitting elements; a power supply unit controlling a load current flowing through the light source unit to be maintained at a constant; a switch element connected in series to the light source unit; and a control unit configured to control on/off of the switch element to modulate a light intensity of illumination light from the light source unit such that a binary communication signal is superimposed on the illumination light. The control unit has a switching circuit to open/close a path between the light source unit and the power supply unit, controls on/off of the switching circuit based on a dimming signal to perform a dimming control on the light source unit by a PWM control, and allows the communication signal to be superimposed on the illumination light in synchronization with an ON time of the switching circuit.

Abstract: Embodiments of the present invention relate to methods and circuits for brightness regulation for at least one light-emitting diode in the field of general lighting, more particularly, for incandescent lamp replacement by means of a supply voltage comprising a brightness level signal, wherein the brightness level signal contained in the supply voltage is decoded and converted into a modulation signal with a duty cycle corresponding to the brightness level signal for the purpose of driving a driver circuit for the at least one light-emitting diode.

Abstract: According to one or more embodiments, an inverter provides a light source with an input voltage. A protection circuit shuts down the inverter based on an overvoltage protection level that is detected based on the input voltage. A protection circuit control part shuts down the operation of the protection circuit during a predetermined interval. Abnormal operation of the protection circuit caused by a high voltage provided when the light source is turned on may be prevented. Therefore, a turn-on defect of the light source may be prevented.

Abstract: The present application is generally directed to systems and methods for control and management of lighting components connected in a network. A user specified rule is executed to control lighting effects in a lighting network which comprises an interface module in communication with one or more lighting control modules. The interface module may receive a rule for controlling a lighting network. The rule may comprise a user identified input and a user specified lighting effect to occur responsive to the user identified input. The interface module detects receipt of the user identified input and executes the rule to trigger the user specified lighting effect via the one or more lighting control modules.

Abstract: Methods for manufacturing a light source circuit board having one or more light emitting components that include providing at least one circuit component on a light source circuit board, wherein the at least one circuit component has an electrical circuit constant that specifies one or more performance parameters for the light source. The methods also include measuring the electrical circuit constant of the at least one circuit component. The methods also include identifying one or more performance parameters for the light source based on the measured electrical constant.

Abstract: Features of the invention are related to drive circuits that provide both power factor correction and voltage conversion in a single circuit and in some instances drive an LED array. This single stage converter uses a SEPIC or Cuk topology and can operate LED arrays that have DC voltages above or below the AC line voltage. An output side filter and bulk energy storage device is placed at the output of the circuit. Bulk energy storage can be provided by an inductor, a capacitor, or a combination of an inductor and a capacitor. The output side filtering can be provided by a capacitor or a capacitor and an inductor. The circuit also includes a switch and a switch control device for controlling the switch to provide power factor correction.

Abstract: A light emitting diode (LED) lighting system and method are disclosed. The LED lighting system and method include an LED controller to accurately control a current in an LED system. The LED controller includes components to calculate, based on the current and an active time period of an LED current time period, an actual charge amount delivered to the LED system wherein the LED current time period is duty cycle modulated at a rate of greater than fifty (50) Hz and to utilize the actual charge amount to modify and provide a desired target charge amount to be delivered during a future active time period of the LED current time period. The LED system and method further involve components to compare the actual charge amount to a desired charge amount for the active time period and compensate for a difference between the actual charge amount and the desired charge amount during the future active time period.

Abstract: A harbor lighting control apparatus is provided, which includes a plurality of slaves to perform on control or off control, and dimming control with respect to a light emitting diode (LED) array light source mounted to a lighthouse when an on control signal or off control signal, and a dimming control signal are received, and to transmit a result of the control as acknowledge signals, and a master to transmit the on control signal or off control signal and the dimming control signal to all of the plurality of slaves by a broadcast scheme, to transmit the on control signal or off control signal and the dimming control signal to an individual slave by a unicast scheme, and to recognize operational states of the plurality of slaves by receiving the acknowledge signals from the plurality of slaves. Accordingly, stable and reliably control of the harbor lighting is enabled.

Abstract: A usage time correcting engine, and corresponding method, system, apparatus, and computer product are provided. Over a period of time that an LED lighting fixture is being used to provide light, a usage time correcting engine indirectly measures an internal temperature of a component of the fixture. The indirect measurement is based on a measured external temperature of the component and power output supplied to or provided by the component. The usage time correcting engine determines a multiplier as a function of the indirectly measured internal temperature. The usage time correcting engine multiplies the period of time by the multiplier to provide a corrected measurement of usage of the component. In some examples, the usage time correcting engine determines a remaining lifetime of the LED lighting fixture from the corrected measurement and then reports the remaining lifetime to a user by way of a log, flashing light or other notification/indication.

Abstract: Embodiments of the disclosure provide a system for selecting a color show generated by LED landscape, pool, and/or spa lights. The system can include an overlay indicating the color shows available to select from. A selector adjacent to the overlay can be positioned to select one of the color shows. The system includes a microcontroller in communication with the selector and a triac circuit in communication with the microcontroller. The microcontroller controls the LED landscape, pool, and/or spa lights using the triac circuit in response to the position of the selector.

Abstract: A system includes a single-inductor-multiple-out (SIMO) converter having storage circuitry in communication with a plurality of output channels, and a controller that controls and measures current flow through the SIMO converter. A signal generator may output switching signals to store current in the storage circuitry and discharge the stored current into the plurality of output channels. The discharged current may be measured and compared to a desired current draw through the output channels over a sample period. A compensator may determine whether to change one or more timing parameters used to control the flow of current through the SIMO converter.

Abstract: A light source control device is for controlling a solid-state light source array having a plurality of solid-state light sources connected in series to each other, and includes a detector (a current detection resistor, voltage detection resistors, and operational amplifiers) adapted to detect at least one of a voltage applied to the solid-state light source array and a current supplied to the solid-state light source array, and a control circuit adapted to determine whether or not discontinuity of at least one of the voltage and the current is present using a detection result of the detector, and change control of one of the current and electrical power performed on the solid-state light source array if it is determined that the discontinuity is present.

Abstract: An LED lamp control circuit directly drives an array of series or parallel connected LEDs with current directly derived from the rectified AC voltage. Electrolytic capacitors are eliminated, and the circuit is independent of forward bias voltage of the LEDs, which vary by lot and manufacturer. For example, in an embodiment, an light-emitting diode (LED) lamp control circuit includes a transistor, an LED load comprising one or more LEDs, a power storage device configured to provide power to the LED load, and a controller circuit configured to control the transistor to charge and discharge the power storage device based on sensed voltages of a first node and a second node and a current passing through the power storage device. The power storage device and the LED load are arranged in parallel between the first node and the second node. A voltage source is coupled to the first node and a first terminal of the transistor is coupled to the second node. A second terminal of the transistor is coupled to ground.

Abstract: A light emitting apparatus disclosed herein comprises a first control apparatus, a first light emitting device, a sense apparatus, a second control apparatus, a power source and a second light emitting device, wherein the second light emitting device is electrically connected to the power source which is not connected to the first light emitting device. The sense apparatus senses both temperature and current of the first light emitting device to generate a second driving signal. The second driving signal is then provided to control the second light emitting device to emit a light for compensating the CCT shift of the light emitted by the first light emitting device.

Abstract: The present disclosure provides devices, circuits, and methods for driving an LED display panel, so as to ensure the delivery of equal global charge at minimum gray scale. In one example, the circuit of the present disclosure includes a current source, a detection module, and a measurement module. The current source is configured to generate a current signal for the LEDs. The detection module is configured to detect a forward voltage of the LEDs in response to a low current applied to the LEDs. The detection module is further configured to hold the detected forward voltage. The measurement module is configured to measure a time period for an anode voltage of the LEDs to rise to the detected forward voltage in response to a display current applied to the LEDs.

Abstract: The present disclosure is directed to a solution providing multi-state power management. In some aspects, the design of the multi-state power management system (MPMS) facilitates switching to battery back up power upon identifying a power outage and further controlling the intensity level of a load (e.g., a light source) such that the light run time meets a minimum required run time. The MPMS may be designed and configured to identify a power outage and a battery status based on the voltage at a voltage input of the lighting device. The design may also include controlling the intensity level of the light source responsive to temperature measurements, e.g., ambient temperature or the temperature of one or more components, to maintain the health of the system.

Abstract: An exemplary lighting control system and method to use the same in which the lighting system may incorporate wireless communications between a DALI controller and DALI controlled devices while maintaining adherence to DALI protocol. The system comprises a DALI protocol based controller (master) connected via a first two wire data bus (e.g. a twisted pair wire) to a controller-side wireless module. The controller-side wireless module communicates via a wireless communication protocol (e.g. Wi-Fi, Zigbee) to at least one device-side wireless module. Each device-side wireless module is connected to a DALI stream via a second two wire data bus to at least one DALI ballast (slave) which is connected to at least one lamp bank. Additional devices may be connected to the DALI stream.

Abstract: A computing device is disclosed. The computing device includes a housing having an illuminable portion. The computing device also includes a light device disposed inside the housing. The light device is configured to illuminate the illuminable portion.

Abstract: A lighting system for areal illumination is disclosed which may include a remote driver and a plurality of fixtures including luminaires. The luminaires may include a light source whose output light level can be adjusted, a light sensor co-located therewith adapted to measure light received from adjacent fixtures. The remote driver may provide power for the light sources of the luminaires.

Abstract: Various methods and apparatus for controlling brightness of a light emitting apparatus include controlling a brightness of a light emitting device based on a brightness value, receiving a message over a network, and detecting a modulation of a power input of the light emitting apparatus. The brightness value is changed based on both the message and the modulation.

Abstract: A semiconductor light emitting element drive device includes: a converter circuit configured to supply a light source unit with a load current from a first-primary winding; and a current regulation circuit. The converter circuit further includes a second-secondary winding. The current regulation circuit includes a switching device (second switching device) connected in series with the second-secondary winding. In a dimming ratio of the light source unit is lower than a first ratio, the second switching device is controlled to ON and OFF so as to decrease the load current through the light source unit by a shunt of a part of the energy stored in the primary winding.

Abstract: A ballast including a latching circuit is provided. The ballast includes an inverter circuit for providing an oscillating voltage signal to energize a lamp set, a control circuit for controlling operation of the inverter circuit, and a voltage supply circuit for providing a supply voltage to the control circuit. The ballast also includes a fault detection circuit for detecting a fault condition and a latching circuit connected to the fault detection circuit. The latching circuit is configured to drain the supply voltage and thereby disable the control circuit so that operation of the inverter circuit is discontinued during a fault condition.

Abstract: An illumination device includes a metal base substrate in a flat planar shape, a plurality of LED modules, and a driving unit which drives each of the LEDs arranged on the metal base substrate. The LED modules have an organic substrate, a plurality of LEDs which are arranged on the organic substrate, a metal member, LED control signal terminals which are set on the edge of the organic substrate, and voltage feed terminals which are set on the edge of the organic substrate. The metal member corresponds to each LED and to which the heat from the LEDs is conducted, and which is electrically connected via a switch element from an electrode of the LED, and which penetrates the organic substrate toward its width direction from the LED mounting surface of the organic substrate and is exposed from the opposite surface.

Abstract: The invention provides a method for intuitively guiding a human to a reference location, such as an emergency exit, with a lighting system comprising a plurality of light sources along a pathway to the reference location. The lights shine with an intensity dependent upon the distance to the reference location, in particular the intensity of the light increases with decreasing distance to the reference location. The location of the emergency can be determined through emergency sensors, so that the intensity of the light sources is then controlled to lead away from the danger to the nearest safe exit.

Abstract: A method is disclosed of controlling a LED, comprising driving the LED with a DC current for a first time, interrupting the DC current for a second time such that the first time and the second time sum to a period, determining at least one characteristic of the LED while the DC current is interrupted, and controlling the DC current during a subsequent period in dependence on the at least one characteristic. The invention thus benefits from the simplicity of DC operation. By operating at the LED in a DC mode, rather than say in a PWM mode, the requirement to be able to adjust the duty cycle is avoided. By including interruptions to the DC current, it is possible to utilize the LED itself to act as a sensor in order to determine a characteristic of the LED. The need for additional sensors is thereby avoided.

Abstract: A wireless battery-powered daylight sensor for measuring a total light intensity in a space is operable to transmit wireless signals using a variable transmission rate that is dependent upon the total light intensity in the space. The sensor comprises a photosensitive circuit, a wireless transmitter for transmitting the wireless signals, a controller coupled to the photosensitive circuit and the wireless transmitter, and a battery for powering the photosensitive circuit, the wireless transmitter, and the controller. The photosensitive circuit is operable to generate a light intensity control signal in response to the total light intensity in the space. The controller transmits the wireless signals in response to the light intensity control signal using the variable transmission rate that is dependent upon the total light intensity in the space. The variable transmission rate may be dependent upon an amount of change of the total light intensity in the space.

Abstract: Board level conditions associated with the operation of multiple LEDs are sensed and used to control a driver that powers the LEDs. The driver is controlled via a 0-10V control interface. The board-level conditions include, but are not limited to, temperature, ambient light, light intensity, operating time, time of day, current, and voltage. An on-board intelligent (OBI) controller processes the 0-10V control signal before it is provided to the driver to better control the LEDs. In some systems the OBI controller works in conjunction with a separate 0-10V controller that controls one or more luminaires.

Abstract: Circuits and methods for driving electrical loads, where each is driven according to a desired current. A circuit comprising a switch mode converter comprising a transformer with primary and secondary windings, the primary connected to a voltage supply via one or more input control switches; output circuits, each comprising a switch connecting a load to an output of the secondary, each load series connected with a respective switch and in parallel with a capacitor; and a switching control circuit for control of each of the output circuit switches and for sensing a current through the loads. The switching control circuit operates the output circuit switches to maintain set current through the loads, the switching control circuit configured in successive output cycles of the switch mode converter to operate each output circuit switch in an order dependent on a forward voltage of each of the respective loads.

Abstract: An antenna sensor includes an antenna operable to receive and/or transmit radio frequency (RF) signals, and one or more sensors operably connected to the antenna and configured to monitor at least one condition and to output sensor signals. A single connection is provided for connection to an electronic device to transfer RF signals from the antenna and sensor signals from the one or more sensors to the electronic device.

Abstract: Mechanisms for light management include a light emitting diode (LED) light bulb. The LED light bulb includes multiple light emitting diodes (LEDs) configured for illumination in the LED light bulb and includes a battery. A base is configured to fit a standard socket designed for an incandescent light bulb, and the base is configured to operatively connect to an electrical power source. A module is operative to detect a residual voltage of the power source when a control for powering the LED light bulb is powered off. The module is configured to determine that a power outage occurred and operative to switch to battery power from the battery in response to not detecting the residual voltage of the power source.

Abstract: A lighting device comprising first, second and third groups of solid state light emitters, the first group emitting light having a dominant wavelength of 430 to 490 nm, the second group at 525 to 575 (in some devices 540 to 575 nm), the third group at 610 to 640 nm. In some devices, wavelength of light from emitters in first and second groups, and light from second and third groups, differs by at least 70 nm. Some devices emit light having CRI Ra of at least 70 when first, second and third groups of emitters are illuminated. Also, a lighting arrangement comprising first, second and third groups as above, in addition to a fourth emitter emitting light of dominant wavelength outside the ranges for the first, second and third groups, and not more than 10 nm different from a dominant wavelength of a color on an item to be illuminated.