Abstract: In a single lighting device including a large number of light-emitting elements (LEEs), the LEEs are divided into separately powered groups, and different combinations of the groups are fully energized to achieve the desired overall brightness. In some embodiments, the number of LEEs in each group has a binary relationship to the other groups. The resolution of the dimming is the brightness of the smallest group. In one example of five binary weighted groups of LEEs, 32 brightness levels can be achieved while the LEEs in the energized groups are fully ON. Thus, since there is no high frequency switching, there is substantially no power dissipation by the dimming control system, and there is limited noise or EMI created. The dimming control can be easily implemented with a logic circuit controlling a transistor switch for each group.

Abstract: Methods and circuits for controlling LEDs are disclosed. In one embodiment, a multistage driver for driving a plurality of serially connected LEDs includes a voltage regulator circuit configured to receive a rectified AC voltage, where the voltage regulator circuit includes a depletion device configured to generate a unregulated voltage using the rectified AC voltage, a band gap voltage reference circuit configured to generate a plurality of reference voltages using the unregulated voltage, and a current setting circuit configured to control the plurality of serially connected LEDs using the plurality of reference voltages.

Abstract: The present invention provides a voltage generation circuit, comprising a control unit, a controlled unit and an output unit, and the control unit receives a trigger signal to generate a control signal having a preset delay, and the control unit is further coupled to the controlled unit to control the controlled unit to be in a first state in a duration of the preset delay and to be in a second state in a duration of a non-preset delay, and the output unit outputs a first drive voltage to the drive unit as the controlled unit is in the first state and to output a second drive voltage to the drive unit as the controlled unit is in the second state, and the first drive voltage is smaller than the second drive voltage to achieve decreasing the drive voltage to lower power consumption of the data drive chip.

Abstract: The present invention provides an LED backlight color temperature adjustment circuit, including a driving chip, an LED backlight module and a control module. The driving chip includes: a driving unit, employed to drive a display panel to show an image; an image data extraction unit, extracting a present display image data of the display panel; an image data analysis unit, employed to calculate a deviation value of the color temperature of the present display image data and a standard color temperature; and a color temperature adjustment unit, employed to generate and output a color temperature adjustment according to the deviation value of the color temperature of the present display image data and the standard color temperature. The LED backlight module includes a plurality of first LEDs which are identical and coupled in series and a plurality of first LEDs which are identical and coupled in series.

Abstract: A light-emitting apparatus includes: a substrate; a plurality of LED chips disposed on the substrate and including a plurality of blue LED chips which emit blue light and a plurality of red LED chips which emit red light; and a sealing member that contains a yellow phosphor and seals the plurality of LED chips together. The plurality of LED chips include: a first LED chip group made up of the blue LED chips; a second LED chip group made up of the red LED chips and disposed around the first LED chip group in an annular shape centered on an optical axis; and a third LED chip group made up of the blue LED chips and disposed around the second LED chip group in an annular shape centered on the optical axis.

Abstract: A power supply includes an input for receiving a first DC voltage, an output for outputting a second DC voltage, a voltage conversion circuit configured to convert the first DC voltage into the second DC voltage, and a control circuit configured to control the voltage conversion circuit to vary a voltage value of the second DC voltage. The control circuit is configured to control the voltage conversion circuit so as to decrease the voltage value of the second DC voltage from a first voltage value to a second voltage value for a predetermined duration every time a predetermined period elapses. The first voltage value is equal to or greater than a voltage value necessary to keep lighting a light source. The second voltage value is smaller than the voltage value necessary to keep lighting the light source.

Abstract: A load control device for controlling the amount of power delivered to an electrical load (e.g., an LED light source) comprises an isolated forward converter comprising a transformer, a controller, and a current sense circuit operable to receive a sense voltage representative of a primary current conducting through to a primary winding of the transformer. The primary winding is coupled in series with a semiconductor switch, while a secondary winding is adapted to be operatively coupled to the load. The forward converter comprises a sense resistor coupled in series with the primary winding for producing the sense voltage that is representative of the primary current. The current sense circuit receives the sense voltage and averages the sense voltage when the semiconductor switch is conductive, so as to generate a load current control signal that is representative of a real component of a load current conducted through the load.

Abstract: A system allows a light fixture to have a wider range of color temperatures (CCT) while limiting the warmest temperature reached at full intensity. The CCT of the light output may be controlled independently of intensity across a certain range of CCT and dependent on intensity across another range. In an implementation, both intensity and CCT may be adjusted from a single handle, where the interface positions may be divided into multiple zones. In another implementation, intensity may be adjusted from a first handle, while CCT may be adjusted from a second handle. The CCT of the light output may be limited to cooler levels when the intensity is higher, and/or the intensity of the light may be limited to lower levels when the CCT is warmer.

Abstract: A device and method for controlling the supply of power to light sources, in which a DC/DC converter is capable of delivering a voltage VMAX to the light sources. The forward voltage of the light sources depends on temperature and may temporarily exceed VMAX at low temperatures. The invention proposes means that allow the required forward voltage to be decreased automatically depending on a measurement of ambient temperature.

Abstract: A system having an alternating current (AC) driven LED unit, an AC voltage regulator, and a controller is provided. The AC driven LED unit includes a first LED and a second LED coupled in reverse parallel. The AC voltage regulator is operable to receive AC voltage originating from an AC voltage source, regulate the AC voltage according to control signals from the controller, and apply regulated AC voltage to the AC driven LED unit, so as to enable the first LED and the second LED to emit light according to the regulated AC voltage. In addition, a method is provided for driving the LED by regulating the AC voltage. By regulating the AC voltage using the AC voltage regulator, benefits of restraining voltage fluctuations, reducing THD, improving power factor, providing dimming control, and mitigating flicker phenomenon can be achieved.

Abstract: An LED backlight controller combines global/hybrid and local brightness/dimming control for an LED backlight illuminator with local regions illuminated by associated LED strings. Global/hybrid brightness/dimming control performs hybrid digital modulation control for a predefined lower range of brightness levels, with string current maintained at a substantially constant level associated with a predefined maximum brightness for the lower range (controlling brightness by adjusting digital modulation, such as PWM duty cycle, up to a maximum), and performs hybrid string current control for a predefined higher range of brightness levels (controlling brightness by adjusting string current). Local dimming control is performed by introducing a local digital modulation signal into a hybrid digital modulation control path for the associated string, so that digital modulation for the associated string is a combination of local digital modulation and global/hybrid digital modulation.

Abstract: A single board light engine includes an AC to AC step driver that selectively powers multiple LED segments by controlling tap points between the LED segments as the input voltage goes from zero crossover to maximum voltage and returns to zero crossover. The step driver may power a first LED segment, a second LED segment, both the first and second LED segments, or none of the LED segments depending upon the input voltage level. The LEDs within an LED segment may share a characteristic that differs from a characteristic shared by LEDs in another segment, which allows the LED fixture to provide a variety of lighting effects.

Abstract: Provided is a lighting system that includes a plurality of lighting elements which emit light, a power supply which supplies power, a lighting driver comprising a microcontroller and which outputs power to the plurality of lighting elements for operation thereof; and a control system which transmits a control signal to the microcontroller to initiate a standby mode of the plurality of lighting elements. The microcontroller receives the control signal and decreases output power supplied to the plurality of lighting elements, while remaining in a low power consumption mode for communicating with the control system during standby mode.

Abstract: Described herein are systems, devices, and methods related to adjusting the intensity of specific wavelengths in an illumination panel based on the presence of a person near the panel. By reducing some emitted wavelengths, such as wavelengths associated with blue light, when such wavelengths are not needed or desired, the lifetime and/or efficiency of the lighting panel can be increased. The systems, devices, and methods can be used to reduce energy costs and also to delay the aging of lighting panels.

Abstract: In a single lighting device including a large number of light-emitting elements (LEEs), the LEEs are divided into separately powered groups, and different combinations of the groups are fully energized to achieve the desired overall brightness. In some embodiments, the number of LEEs in each group has a binary relationship to the other groups. The resolution of the dimming is the brightness of the smallest group. In one example of five binary weighted groups of LEEs, 32 brightness levels can be achieved while the LEEs in the energized groups are fully ON. Thus, since there is no high frequency switching, there is substantially no power dissipation by the dimming control system, and there is limited noise or EMI created. The dimming control can be easily implemented with a logic circuit controlling a transistor switch for each group.

Abstract: The present invention relates to a light emitting device including at least three pairs of half-wave light emitting units, each pair including a terminal of a first half-wave light emitting unit connected to a terminal of a second half-wave light emitting unit, the terminals having the same polarity, a polarity of the connected terminals of one half-wave light emitting unit pair being opposite to the polarity of the connected terminals of an adjacent half-wave light emitting unit. The light emitting device also includes at least two full-wave light emitting units each connected to adjacent pairs of half-wave light emitting units.

Abstract: A light-emitting device is capable of receiving a first voltage signal, a second voltage signal, and a third voltage signal in sequence. The light-emitting device includes a first light-emitting unit, a second light-emitting unit, and a switching. The first voltage signal, the second voltage signal, and the third voltage signal is configured to introduce a first current signal, a second current signal, and a third current signal, respectively. The light-emitting device is configured to emit a first light when introducing the first current signal, the second current signal, and the third current signal. The light-emitting device is configured to emit a second light when introducing the second current signal and the third current signal. The light-emitting device is configured to emit a third light when introducing the second current signal.

Abstract: The present invention relates to a light emitting device including at least three pairs of half-wave light emitting units, each pair including a terminal of a first half-wave light emitting unit connected to a terminal of a second half-wave light emitting unit, the terminals having the same polarity, a polarity of the connected terminals of one half-wave light emitting unit pair being opposite to the polarity of the connected terminals of an adjacent half-wave light emitting unit. The light emitting device also includes at least two full-wave light emitting units each connected to adjacent pairs of half-wave light emitting units.

Abstract: A light fixture includes a light emitting diode (LED) structure, a housing with one or more sensors, and control circuitry that is configured to receive data from the sensor and automatically alter characteristics of light emitted by the LEDs in the fixture in response to the received data.

Abstract: An LED lighting device for AC voltage supply is provided. The device has LEDs that form a whole chain. The LEDs are divided into LED part groups. The device also has multiple serial switching means, multiple shorting links and a control means. The control means is configured to control the shorting links and the serial switching means, to place the whole chain in at least two switch states. The switch states differ in the through voltage of the whole chain.

Abstract: A phase-shift dimming circuit for LED controller having a delay signal generator configured to receive a PWM input signal, and to provide a plurality of pairs of set signal and reset signal, the set signal and the reset signal respectively having pulses; and a plurality of latches configured to respectively receive the plurality of pairs of set signal and reset signal to generate a plurality of PMW output signals, each of the PWM output signals having pulses, and wherein the rising edge of the pulses of the PWM output signals is based on the corresponding set signal pulses, and the falling edge of the pulses of the PWM output signals is based on the corresponding reset signal pulses.

Abstract: The present disclosure provides a backlight driving circuit, a liquid crystal display (LCD) device, and a driving method. The backlight driving circuit includes a monitoring device and a conversion device, the conversion device includes a microcontroller (MCU) and a switch module. A control end of the switch module is coupled to the monitoring device, and the monitoring device outputs a monitoring signal to turn on or turn off the switch module. An input end of a power source of the MCU is coupled to a power end of the backlight driving circuit through the switch module.

Abstract: A load driving apparatus related to an LED lamp and a method thereof are provided. The load driving apparatus includes a PWM-based power converter and a determination circuit. The PWM-based power converter is coupled to the LED lamp, and is configured to: generate a DC operation voltage of the LED lamp; and control a current flowing through the LED lamp in response to a dimming signal, so as to adjust a brightness of the LED lamp. The determination circuit is coupled to the PWM-based power converter and the LED lamp, and is configured to: receive the DC operation voltage; and stop conducting the DC operation voltage to the LED lamp in case that a lamp-off condition of the LED lamp is satisfied.

Abstract: A power supplying apparatus is disclosed, in which an under voltage lock out function is not performed for instantaneous voltage dip even in case that a reference under voltage detection voltage is set at high level. The power supplying apparatus comprises an under voltage detector generating an under voltage lock out signal by detecting voltage dip of an input power and performing an under voltage protection function, wherein the under voltage detector delays the input power for a delay time, which is set, to generate the under voltage lock out signal.

Abstract: A lighting system is disclosed comprising an excitor which drives at least one reactor. The excitor is an electrical waveform generator that creates an AC waveform at a frequency between about 50 kHz and about 100 MHz. The reactor is an under-damped resonant circuit that includes a network of lighting elements. Reactive components are distributed among the lighting elements. These reactive components can regulate the current and voltage to individual lighting elements. The drive system is particularly useful for arrays of low-voltage lighting elements such as LEDs. It is fault tolerant in that the failure of individual elements need not affect the operation of remaining elements, and elements can be added and removed without affecting the serviceability of other elements.

Abstract: A light-emitting diode device having two electrode pads for connecting to an external power comprises a substrate; a plurality of light-emitting diode units on the substrate; and a plurality of conductive connecting structures electrically connecting the plurality of light-emitting diode units; wherein the two electrode pads are encircled by the plurality of light-emitting diode units.

Abstract: An illumination device (1) comprises: input terminals (2) for coupling to AC mains; a LED string (10) connected in series with the input terminals; a rectifier (30), having input terminals connected in series with the LED string; a controllable voltage source (40), having input terminals coupled to the rectifier output terminals; a series arrangement of at least one auxiliary LED (51) and a second ballast resistor (52) connected to the output terminals of the controllable voltage source. The voltage source comprises: a series arrangement of an adjustable first resistor (46) and a second resistor (47) connected in parallel to the input terminals; a tuneable Zener diode (49) connected in parallel to the output terminals, having a control input terminal (48) connected to the node between the two resistors; wherein positive output terminal is connected to positive input terminal and negative output terminal is connected to negative input terminal.

Abstract: An AC lighting system for providing uniform light distribution is disclosed. According to one embodiment, the AC lighting system includes an AC driver and LED packages electrically connected to the AC driver. Each LED package includes a plurality of LED elements and is physically distributed over an illuminating surface of the AC lighting system. The AC driver has a first current sink that drives a first LED group and a second current sink that drives the first LED group and a second LED group. The first LED group includes at least one LED element from each of the LED packages, and the second LED group includes at least one LED element other that the first set of LED elements from each of the LED packages.

Abstract: An optical semiconductor lighting apparatus includes: a housing; a heat discharge block which is made of a metal and is embedded in the housing; an AC direct-connection module which is made of a metal and is embedded in the housing, the AC direct-connection module including a semiconductor optical device which is driven in an AC direct-connection scheme; and an insulation connector which is provided in the AC direct-connection module and is exposed to an outside of the housing for electrical connection with an external power source.

Abstract: Provided is a system for controlling lighting effects. The system comprises a controller and one or more wireless dimmer devices with incorporated digital effects engine. The controller transmits wirelessly and effects parameters to the wireless dimmer devices. The dimmer devices receive the effects parameters, generate output effects parameters using the digital effects engine, and provide the output effects parameters to either dimmer output channels or DMX output channels. The digital effect engine comprises a low frequency oscillator and several random number generators. The random number generators may be used to modulate frequency of the low frequency oscillator and modulate a level of each dimmer output channel. The random number generators are configured to generate independent strings of pseudo-random numbers.

Abstract: System and method are provided for generating a plurality of channel currents. The system includes a channel reference generator configured to receive a first reference current and generate at least a first channel driving current and a second channel driving current, a first channel current divider configured to receive the first channel driving current and generate a first input current, a second input current, and a third input current, a second channel current divider configured to receive the second channel driving current and generate a fourth input current, a fifth input current, and a sixth input current, a first channel driver configured to receive the first input current, the second input current, and the third input current and generate a first channel current, and a second channel driver configured to receive the fourth input current, the fifth input current, and the sixth input current and generate a second channel current.

Abstract: In a semiconductor light emitting device, a light emitting structure includes a first-conductivity type semiconductor layer, an active layer, and a second-conductivity type semiconductor layer, which are sequentially formed on a conductive substrate. A second-conductivity type electrode includes a conductive via and an electrical connection part. The conductive via passes through the first-conductivity type semiconductor layer and the active layer, and is connected to the inside of the second-conductivity type semiconductor layer. The electrical connection part extends from the conductive via and is exposed to the outside of the light emitting structure. An insulator electrically separates the second-conductivity type electrode from the conductive substrate, the first-conductivity type semiconductor layer, and the active layer. A passivation layer is formed to cover at least a side surface of the active layer in the light emitting structure.

Abstract: A method of controlling multiple lamps is applied to an illumination system, which includes an input interface, a signal transmitter, a plurality of signal receivers, a plurality of driving devices, and a plurality of lamps. The method includes the following steps: detect a state of the input interface with the signal transmitter; transmits a corresponding signal with the signal transmitter; each of the signal receivers receives the signal and detects a waveform of an AC power source, and each of the signal receivers transmits a corresponding control signal to the corresponding driving device to control the corresponding lamp at a reference point in the following cycle of the waveform of the AC power source.

Abstract: An illumination system includes an input interface, a phase angle control module, a lamp, and a driving module. The input interface is controllably switched between a first state and a second state. The phase angle control module is electrically connected to an AC power source and the input interface. When the input interface is at the first state, the phase angle control module modifies a voltage waveform of the AC power source to generate a delayed conduction angle in a half wave period of the voltage waveform. The driving module is stored with a control mode, wherein the driving module switches the control mode to control the lamp to emit light in accordance with the delayed conduction angle.

Abstract: Apparatus and associated methods reduce harmonic distortion of a excitation current by diverting the excitation current substantially away from a number of LEDs arranged in a series circuit until the current or its associated periodic excitation voltage reaches a predetermined threshold level, and ceasing the current diversion while the excitation current or voltage is substantially above the predetermined threshold level. In an illustrative embodiment, a rectifier may receive an AC (e.g., sinusoidal) voltage and deliver unidirectional current to a string of series-connected LEDs. An effective turn-on threshold voltage of the diode string may be reduced by diverting current around at least one of the diodes in the string while the AC voltage is below a predetermined level. In various examples, selective current diversion within the LED string may extend the input current conduction angle and thereby substantially reduce harmonic distortion for AC LED lighting systems.

Abstract: A light emitting device including a light emitting component is provided, wherein said light emitting comprising an integrated light emitting diode and a semiconductor field effect transistor. The semiconductor field effect transistor may prevent situations such as overheating and voltage instability by controlling a current passing through the light emitting diode as well as enhancing the ability to withstand electrostatic discharge and reducing cost of the light emitting device in multiple aspects.

Abstract: An LED drive circuit that is connectable to an a.c. power supply via a phase control type light adjuster and drives an LED load, including a discharge portion that consumes energy of a resonance phenomenon generated by a light adjuster capacitance component of the phase control type light adjuster and a light adjuster inductance component of the phase control type light adjuster when a current holding portion of the phase control type light adjuster is turned on.

Abstract: An LED driving device includes a first converter configured to generate a first voltage, a second converter configured to generate a second voltage for driving a plurality of light emitting diodes (LEDs) from the first voltage, and a control circuit connected to an output terminal of the first converter and configured to control a level of the first voltage. The control circuit includes a cut-off circuit including a comparison circuit having hysteresis characteristics and a bleeder circuit.

Abstract: According to one exemplary embodiment, driver circuit coupled between an AC line and a load includes a first semiconductor switch interposed between a bus voltage and a resonant circuit and a second semiconductor switch interposed between the resonant circuit and a ground, where the resonant circuit drives the load. In the driver circuit, the bus voltage has a shape substantially corresponding to a shape of a rectified AC line voltage, thereby increasing a power factor of the driver circuit. The driver circuit can further include a full-bridge rectifier disposed between the resonant circuit and the load. The load can include at least one LED.

Abstract: A device (340, 440, 540) is connected to an output terminal of a controller (330), having a single input terminal connected to a first power terminal of an external power source (305) which outputs an AC voltage between the first power terminal and a second power terminal. The device includes a bleeding circuit (342, 442, 542), and a switching arrangement (344/346, 444/446, 544/546) to detect whether the controller powers a load (320 or disables the load. When the controller is in an OFF state, the switching arrangement connects the bleeding circuit between the output terminal of the controller and the second power terminal to provide a current path between the output terminal of the controller and the second power terminal. When the controller is in an ON state, the switching arrangement disconnects the bleeding circuit between the output terminal of the controller and the second power terminal.

Abstract: A lighting system is disclosed comprising an excitor which drives at least one reactor. The excitor is an electrical waveform generator that creates an AC waveform at a frequency between about 50 kHz and about 100 MHz. The reactor is an under-damped resonant circuit that includes a network of lighting elements. Reactive components are distributed among the lighting elements. These reactive components can regulate the current and voltage to individual lighting elements. The drive system is particularly useful for arrays of low-voltage lighting elements such as LEDs. It is fault tolerant in that the failure of individual elements need not affect the operation of remaining elements, and elements can be added and removed without affecting the serviceability of other elements.

Abstract: A method includes receiving a sense signal having multiple pulses, where the sense signal is based on an output of a dimmer. The method also includes, for each of multiple sampling periods, (i) identifying a pulse duty cycle by sampling at least one pulse in the sense signal and calculating a duty cycle of the at least one pulse and (ii) generating an output value identifying a duty cycle for driving one or more LEDs. The output value is based on the pulse duty cycle. The method further includes generating a holding current for the dimmer (i) during the sampling of the at least one pulse in at least one of the sampling periods and (ii) when the pulse duty cycle is less than a specified threshold. The holding current can be applied continuously when the pulse duty cycle is less than the specified threshold (such as 15%).

Abstract: The disclosure provides a lighting device and a voltage reduction method thereof, wherein the lighting device comprises: an AC power supply generator for generating an AC power source to supply power to other accessories and circuits in the lighting device; m load components, every two adjacent load components forming one head common connection point and one end common connection point respectively for each load component from head to end alternatively; and (m?1) current balancing cells each respectively connected between one head common connection point or one end common connection point and one of two output terminals of the AC power supply generator; wherein the m load components comprise (m?n) low impedance load components therein. The present application can reduce the output voltage of the AC power supply generator with lower cost.

Abstract: In various embodiments, a device for dimming a light source is provided. The device may include a two-wire power supply line having interposed therein a switch for controlling transfer of the power supply towards the light source; a capacitance located downstream of the switch being traversed by a charge current as the switch is switched on; and a pre-charge stage interposed between the switch and the capacitance; the pre-charge stage being configured to limit to a given value the charge current.

Abstract: A backlight driver includes current sources that are connected between LED strings and a number of bias voltages. There can be any number of different bias voltages, each at a ground potential or higher voltage. The bias voltage is selected for a particular LED string in order to reduce a current drop across the current source. This reduces the power consumption of the current source and LED string. Heat dissipation is also reduced.

Abstract: A driver is connectable to an external power supply and configured to output variable electrical power for one or more loads, such as LEDs. A module including a microcontroller is operable to output a control signal that automatically varies the electrical power outputted by the driver. The microcontroller is further configured to be powered by the control signal.

Abstract: Embodiments of the present invention provide a system and method for determining a magnitude of current driving LEDs by sensing a current through a switching transistor and extracting the information of the LED current based on a relationship between the current through the switching transistor and the current driving the LEDs.

Abstract: Improved circuits minimize, or eliminate, energy losses in the supply of energy to control LEDs. Diodes and a capacitor reduce or eliminate LED blinking, and create smooth and continuous, infinitely variable dimming. The components are added to supply power to each LED during the half of the AC cycle where it would normally be turned off. A first added diode allows an added capacitor to charge during the half cycle that the original diode is turned on, but does not allow the other half cycle to discharge the added capacitor. When the added capacitor is charged enough to turn on the original diode, it stays on throughout the AC cycle. The same relationship exists between the second added diode, the added capacitor and the second original diode. Zener diodes protect the LEDs from voltage surges/spikes by shunting current around LEDs when the voltage exceeds the Zener diode's breakdown voltage.

Abstract: Emission systems having solid-state transducers (SSTs) for producing a target chromaticity of light are disclosed herein. An emission system or SST device in accordance with a particular embodiment can include a first emitter having a first plurality of SSTs positioned to emit light having a first chromaticity, and a second emitter having a second plurality of SSTs positioned to emit light having a second chromaticity different than the first chromaticity. The SST device can further include a controller having a first channel with a variable output, coupled to the first emitter to adjust the brightness level of the first emitter, and a second channel with a variable output, coupled to the second emitter to adjust the brightness level of the second emitter.

Abstract: A backlight control module comprises a backlight computing unit configuring a frequency of at least one PWM signal according to a frequency of a frame, when at least one area frame of at least one display area is used for displaying the frame; a timing control unit configuring at least one starting time instant of a period of the at least one PWM signal according to at least one starting time instant of the at least one area frame, respectively; and a PWM unit generating the at least one PWM signal, and configuring at least one width of at least one on-period of the period of the at least one PWM signal according to at least one image data of the at least one area frame, respectively, wherein the at least one on-period is located at an end of the period of the at least one PWM signal, respectively.