Load control device for light emitting diode light source

Abstract

A load control device for controlling the light source may be configured to control a target color temperature near the low end intensity level to converge the color temperature toward one or more color temperatures. The light source may include first and second emitter circuits that emit light having a first color temperature and light having a second color temperature, respectively. The load control device may control the first emitter circuit and the second emitter circuit such that a current color temperature of the accumulated light emitted by the light source is controlled toward a target color temperature. When the target intensity level is less than a threshold intensity level, the control circuit may limit the target color temperature according to at least one limit curve that converges the target color temperature toward at least one of the first color temperature or the second color temperature as the target intensity level decreases toward the low end intensity level.

Description

Cross-reference to related applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 528,290, filed July 21, 2023, the entire disclosure of which is incorporated herein by reference. Background Technology

[0002] Various types of load control systems can be used to configure user environments such as residential or office buildings. Lighting control systems can be used to control lighting loads in a user environment. Each load control system may include various control devices, including input devices and load control devices. Load control devices may receive digital messages for controlling electrical loads, which may include load control commands, from one or more load control devices. Load control devices may be able to directly control electrical loads. Input devices may be able to indirectly control electrical loads via load control devices. Examples of load control devices may include lighting control devices (e.g., dimmers, dimmer switches, electronic switches, ballasts, light-emitting diode (LED) drivers), motorized window coverings, temperature control devices (e.g., thermostats), AC plug-in load control devices, etc. Examples of input devices may include remote control devices, occupancy sensors, daylight sensors, temperature sensors, etc.

[0003] Lamps and displays using efficient light sources such as light-emitting diodes (LEDs) are becoming increasingly popular in many different markets. LED light sources offer many advantages over traditional light sources such as incandescent and fluorescent lamps. For example, LED light sources can consume less power and have a longer lifespan than traditional light sources. In addition, LED light sources may be free of harmful substances and can provide additional specific advantages for different applications. When used for general lighting, LED light sources offer the opportunity to adjust the color (e.g., from white to blue, green, etc.) or color temperature (e.g., from warm white to cool white) of the light emitted from the LED light source to produce different lighting effects. Summary of the Invention

[0004] As described herein, a load control device for controlling the amount of power delivered to a light source can be configured to control the target color temperature of the light source so that the color temperature converges toward one or more color temperatures near a low-end intensity level. The light source may include a plurality of emitter circuits, each configured to emit light at a corresponding color temperature (e.g., a first emitter circuit configured to emit light with a first color temperature and a second emitter circuit configured to emit light with a second color temperature). The load control device may include a plurality of drive circuits, each configured to control a corresponding intensity level of each of the plurality of emitter circuits of the light source (e.g., a first drive circuit configured to control a first intensity level of a first emitter circuit and a second drive circuit configured to control a second intensity level of a second emitter circuit). The load control device may further include a control circuit configured to control the drive circuits so that the current intensity level and current color temperature of the accumulated light emitted by the light source are controlled toward a target intensity level and a target color temperature, respectively. When the target intensity level is less than the threshold intensity level, the control circuit is configured to limit the target color temperature according to at least one limiting curve, which causes the target color temperature to converge toward at least one of a first color temperature or a second color temperature as the target intensity level decreases toward a lower intensity level.

[0005] Additionally, this document discloses a method for controlling the electrical force delivered to a light source having a first emitter circuit configured to emit light having a first color temperature and a second emitter circuit configured to emit light having a second color temperature. The method may include: (1) controlling a first driving circuit to control a first intensity level of the first emitter circuit; (2) controlling a second driving circuit to control a second intensity level of the second emitter circuit; (3) controlling the first and second driving circuits to control the current intensity level and current color temperature of accumulated light emitted by the light source toward a target intensity level and a target color temperature, respectively; and (4) when the target intensity level is less than a threshold intensity level, limiting the target color temperature according to at least one limiting curve, the at least one limiting curve causing the target color temperature to converge toward at least one of the first color temperature or the second color temperature as the target intensity level decreases toward a lower intensity level. Attached Figure Description

[0006] Figure 1 This is a simplified block diagram of an example load control system, such as a light-emitting diode driver system.

[0007] Figure 2 The possible operating points are shown, and their definitions can be derived from... Figure 1 The color temperature achieved by the LED driver system at discrete intensity levels below the threshold intensity level.

[0008] Figures 3-5Several examples of limiting curves are shown, which are used to define the adjustment of the target color temperature of a light source when the target intensity level of the light source is less than a threshold intensity level.

[0009] Figure 6 This is a flowchart of an example process for adjusting the target color temperature of a light source. Detailed Implementation

[0010] Figure 1 This is a simplified block diagram of an example load control system such as a light-emitting diode (LED) driver system 100. The LED driver system 100 may include load control devices for controlling a light source 110, such as a driver module 120 (e.g., a dimming module). The LED driver system 100 may also include a power converter module 130 for powering the light source 110 and / or the driver module 120. For example, the light source 110 of the LED driver system 100 may include multiple emitter circuits, such as emitter circuits 111, 112 (e.g., LED circuits). Each emitter circuit in emitter circuits 111, 112 may include one or more emitters. The emitters of each emitter circuit 111, 112 may be electrically coupled together in series and / or parallel connections. Thus, the emitters of each emitter circuit 111, 112 can be uniformly controlled. The driver module 120 may control the emitter circuits 111, 112 to adjust the intensity level (e.g., illumination intensity level or luminance) and / or color (e.g., color temperature) of the accumulated light emitted by the light source 110. In some examples, the light source 110, driver module 120, and power converter module 130 may be separate devices (e.g., housed in separate housings and / or mounting devices). Furthermore, the light source 110, driver module 120, and power converter module 130 may be housed in a single housing or some combination thereof (e.g., when the LED driver system 100 is a controllable light source). Although Figure 1 A light source 110 with emitter circuits 111, 112 is shown, but the light source 110 may also include more than two emitter circuits.

[0011] Each transmitter circuit in transmitter circuits 111 and 112 is in Figure 1The light source 110 is shown as a single LED, but as described above, it may each include multiple LEDs connected in series (e.g., LED strings or chains), multiple LEDs connected in parallel, or suitable combinations thereof, depending on the specific lighting system. Emitter circuits 111 and 112 may each represent a string of one or more LEDs, wherein all LEDs in each string are configured to emit light at the same color temperature. The LED strings represented by each emitter circuit in emitter circuits 111 and 112 may be configured to emit light at different color temperatures. Furthermore, the emitter circuits of light source 110 are not limited to LEDs, and in some examples, other technologies such as OLEDs may be used. For example, light source 110 may include strip lighting (e.g., bar lighting), wherein each emitter circuit in emitter circuits 111 and 112 is a separate LED string, for example, each string having a corresponding and different color temperature. When light source 110 is strip lighting, each lighting strip may be mounted on the same strip, mounted on different strips, housed individually, housed together in a housing, or some combination thereof.

[0012] Each of the emitter circuits 111 and 112 can be configured to emit light at a color temperature (e.g., different color temperatures) along a blackbody trajectory. For example, the first emitter circuit 111 can represent an LED string at a first color temperature T1, and the second emitter circuit 112 can represent an LED string at a second color temperature T2. The first color temperature can be greater than the second color temperature. For example, the first color temperature can be a cool white temperature (e.g., such as about 3000 K), and the second color temperature can be a warm white temperature (e.g., such as about 1800 K). Although described in the context of these color temperatures, the emitter circuits 111 and 112 can be configured to emit light according to any color temperature. Although described as including two emitter circuits, the LED driver system 100 can include more or fewer emitter circuits (e.g., and configured with the same or different numbers of LEDs) each configured to emit light at different color temperatures. Additionally, the LED driver system 100 may include more emitter circuits than the two emitter circuits 111, 112, for example, some of which are at a first color temperature, and one or more of the remaining emitter circuits are at a second, different color temperature. Furthermore, as described herein, each LED in each emitter circuit of emitter circuits 111, 112 may be configured to emit light at a nominal or rated color temperature, for example, as defined by ANSI C78.377-2011.

[0013] Power converter module 130 may include power converter circuit 132, which can receive source voltage, such as AC mains voltage V, via thermal connection H and neutral connection N. AC The power converter circuit 132 can cross the bus capacitor C.BUS Generate DC bus voltage V BUS (For example, approximately 15V to 50V). The power converter circuit 132 may include, for example, a boost converter, a buck converter, a buck-boost converter, a flyback converter, or a single-ended primary inductor converter (SEPIC). The power converter circuit 132 can be a UK converter or any other suitable power converter circuit used to generate the appropriate bus voltage. Power converter circuit 132 can provide electrical isolation between the AC power supply and driver module 120 and / or transmitter circuits 111, 112. Power converter circuit 132 can also operate as a power factor correction (PFC) circuit to adjust the power factor of the LED driver system 100 toward a power factor of 1. Although shown as connected to an AC power supply (e.g., AC trunk line voltage V...), it is not directly connected to the power supply. AC However, in other examples, the LED driver system 100 may be coupled to a direct current (DC) power supply. Here, the power converter module 130 may not be necessary, or it may be capable of converting the DC source voltage of the DC power supply to the DC bus voltage V. BUS (For example, a desired value between approximately 15V and 50V).

[0014] The driver module 120 may include multiple driver circuits, such as those for controlling (e.g., individually controlling) the electrical force delivered to the light source 110 and the individual intensity level L of the light emitted by each of the respective emitter circuits 111, 112 of the light source. IND1 L IND2 LED driver circuits 121 and 122 (e.g., illumination intensity level and / or luminous flux). Both LED driver circuits 121 and 122 can receive bus voltage V. BUS (For example, this bus voltage can be generated by power converter circuit 132). Each LED driver circuit in LED driver circuits 121, 122 can be configured to adjust (e.g., independently adjust) the corresponding LED voltage V generated across the corresponding emitter circuits 111, 112. LED1 V LED2 The magnitude (e.g., average magnitude). For example, each LED driver circuit in LED driver circuits 121, 122 can be configured to respond to the corresponding LED voltage V. LED1 V LED2 Pulse width modulation is performed to adjust the individual intensity level L of the light emitted by the corresponding transmitter circuits 111 and 112. IND1 L IND2 In some examples, each LED driver circuit in LED driver circuits 121, 124 can receive a bus voltage V. BUS Furthermore, the corresponding LED current I conducted through transmitter circuits 111 and 112 can be adjusted.LED1 I LED2 The magnitude (e.g., average magnitude). Each LED driver circuit in LED driver circuits 121, 122 may include regulation circuitry, such as for controlling the corresponding LED voltage V. LED1 V LED2 and / or the corresponding LED current I LED1 I LED2 A switching regulator (e.g., a buck converter) that measures the magnitude of a quantity. Although Figure 1 A driver module 120 with LED driver circuits 111, 112 is shown, but the driver module 120 may also include more than two LED driver circuits. In some examples, the driver module 120 may include a plurality of LED driver circuits, wherein each of the plurality of LED driver circuits is configured to control an individual intensity level of one of the plurality of emitter circuits of the light source 110.

[0015] The driver module 120 may include control circuitry 124 for controlling LED driver circuits 121, 122 to control the individual intensity level L of each emitter circuit in emitter circuits 111, 112 of the light source 110. IND1 L IND2 The control circuit 124 may include one or more of, for example, a microprocessor, a microcontroller, a programmable logic device (PLD), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or any other suitable processing device or controller. The control circuit 124 may be configured to control the LED driver circuits 121, 122 to control the current intensity level L of the accumulated light emitted by the light source 110. PRES (e.g., current brightness) and / or current color temperature T PRES For example, control circuit 124 can be configured to operate at high strength level L. HE (For example, the maximum strength level, such as approximately 100%) and the low-end strength level L LE (For example, a minimum intensity level, such as approximately 0.1% to 1.0%) controls the current intensity level L of the accumulated light emitted by the light source 110. PRES The control circuit 124 can be configured to generate one or more drive signals V for controlling the respective LED driver circuits 121, 122. DR1 V DR2 The control circuit 124 can be configured to operate at a frequency f. OP (For example, approximately 2.05 kHz) Generate one or more drive signals V DR1 V DR2 Each drive signal in the process causes one or more drive signals V to... DR1 V DR2Each drive signal in the process is controlled by the operation cycle T. OP (For example, approximately 488 microseconds) characterization. For example, control circuit 124 can be configured to adjust the first drive signal V. DR1 On-time T ON1 To adjust the individual intensity level L of the first transmitter circuit 111 IND1 And adjust the second drive signal V DR2 On-time T ON2 To adjust the individual intensity level L of the second transmitter circuit 112 IND2 (For example, simultaneously operating frequency f) OP and / or operation period T OP (Maintaining a constant value). Control circuit 124 can be configured to adjust (e.g., independently adjust) the first drive signal V. DR1 On-time T ON1 Second drive signal V DR2 On-time T ON2 To adjust the current intensity level L of the accumulated light emitted by light source 110. PRES and / or the current color temperature T PRES .

[0016] The control circuit can be controlled by the first drive signal V. DR1 On-time T ON1 Second drive signal V DR1 On-time T ON2 The minimum step size in the adjustment is Δ T-ON Characterized by (for example, approximately 26 nanoseconds), this minimum step size can also establish the minimum on-time T. ON-MIN The control circuit 124 can transmit the first drive signal V DR1 On-time T ON1 Second drive signal V DR2 On-time T ON2 Adjust to this minimum conduction time. Control circuit 124 can be configured to adjust the target intensity level L of light source 110. TRGT Adjusted to high-end strength level L HE Compared with low-end strength level L LE The number of spaces between them (e.g., equally spaced) is N. L Discrete intensity levels (e.g., approximately 2000) can produce an intensity level step size Δ of approximately 0.05%. L .

[0017] Control circuit 124 can be configured to control the cumulative on-time T of both transmitter circuits 111 and 112. ON-C Adjust the corresponding drive signal V during the period DR1 V DR2The duty cycles d1 and d2 are used to adjust the current color temperature T of the accumulated light emitted by the light source 110. PRES For example, the cumulative conduction time T ON-C It can be the first driving signal V DR1 On-time T ON1 Second drive signal V DR2 On-time T ON2 The sum of d1 and d2 makes the combined duty cycle d1 and d2 equal to 100%. Control circuit 124 can be configured to determine the current color temperature T of the accumulated light emitted by light source 110. PRES Controlled to the target color temperature T TRGT The corresponding drive signal V DR1 V DR2 The duty cycles d1 and d2. For example, the control circuit 124 can be configured based on the target color temperature T. TRGT To calculate the corresponding driving signal V DR1 V DR2 The duty cycles d1 and d2.

[0018] Then, the control circuit 124 can determine the corresponding drive signal V. DR1 V DR2 On-time T ON1 T ON2， To achieve the target intensity level L TRGT and target color temperature T TRGT For example, the control circuit 124 can be based on the target intensity level L. TRGT And such as based on target color temperature T TRGT The corresponding drive signal V is calculated based on the determined duty cycles d1 and d2. DR1 V DR2 Expected conduction time T ON1-D T ON2-D ,For example, T ON1-D = d1· L TRGT · T OP ,and T ON2-D = d2· L TRGT · T OP .

[0019] Then, the control circuit 124 can adjust the desired on-time T. ON1-D T ON2-D Each expected conduction time in the range is rounded up to the minimum step size Δ. T-ON The closest multiple is used to determine the corresponding drive signal V DR1 V DR2 On-time T ON1 , TON2 Each conduction time in, for example, T ON1 = ROUND(T ON1-D ) = α · Δ T-ON ,and T ON2 = ROUND(T ON2-D ) = β · Δ T-ON , Where α and β are integer values. Then, the control circuit 124 can use the corresponding on-time T. ON1 , TON2 To generate drive signals VDR1 , VDR2 To control the accumulated light emitted by light source 110 to the target intensity level L. TRGT and target color temperature T TRGT .

[0020] Although Figure 1 Although not shown, LED driver circuits 121 and 122 can generate one or more feedback signals, which can be received by control circuit 124 and can indicate the magnitude of corresponding operating characteristics (e.g., LED current and / or luminous flux) of the respective emitter circuits 111 and 112 of the light source 110. Additionally, driver module 120 may include one or more feedback circuits (not shown), which can be external to LED driver circuits 121 and 122 and can generate one or more feedback signals received by control circuit 124. Control circuit 124 can adjust the LED voltage V towards a corresponding target voltage in response to the feedback signals. LED1 V LED2 The average value of the voltage of each LED in the circuit. In some examples, the control circuit 124 can adjust the LED current I toward a corresponding target current in response to a feedback signal. LED1 I LED2 The average value of the current of each LED in the data.

[0021] The control circuit 124 can be configured to move towards the target intensity level L TRGT (e.g., target brightness) Adjust (e.g., dimming) the current intensity level L of the accumulated light emitted by the light source 110. PRES The adjustment range can span the dimming range of the controllable lighting device, for example, at the low intensity level L. LE With high-end strength level L HE Between. In some examples, the current intensity level L of each emitter (e.g., LED) is... PRES It can depend on the LED voltage V generated by the transmitter circuits 111 and 112. LED1 V LED2The magnitude and / or the LED current I conducted through the transmitter circuit LED1 I LED2 The value of the quantity. The control circuit 120 can be configured to move towards the target color temperature T. TRGT Adjust the current color temperature T of the accumulated light emitted by light source 110 PRES The adjustment range can be between a cool white temperature (e.g., approximately 1800 K) and / or a warm white temperature (e.g., approximately 3000 K). In some examples, the current color temperature T of the accumulated light emitted by light source 110 is... PRES It can depend on the LED voltage V across the transmitter circuit. LED1 V LED2 The magnitude and / or the LED current I through the transmitter circuit LED1 I LED2 The magnitude of the light emitted by the emitter circuit (e.g., and / or the intensity level of the light emitted by the emitter circuit) and the color temperature of each emitter circuit (e.g., as a function of it).

[0022] The LED driver system 100 may include a communication circuit 126 coupled to the control circuit 120. The communication circuit 126 may include wired communication circuitry. Alternatively or additionally, the communication circuit 126 may include wireless communication circuitry, such as an RF transceiver coupled to an antenna to transmit and / or receive radio frequency (RF) signals. The wireless communication circuitry may be an RF transmitter for transmitting RF signals, an RF receiver for receiving RF signals, or an IR transmitter and / or receiver for transmitting and / or receiving infrared (IR) signals. Alternatively or additionally, the communication circuit 126 may be coupled to the thermal connection H and neutral connection N of the LED driver system 100 to transmit control signals via electrical wiring using, for example, power line carrier (PLC) communication technology. The control circuit 124 may be configured to receive and / or determine the strength level L of a command from messages (e.g., digital messages) received via the communication circuit 126. CMD and / or command color temperature T CMD The control circuit 124 can be configured to respond to the strength level L of a command received via a message. CMD and / or command color temperature T CMD And determine the target intensity level L of light source 110 TRGT Or target color temperature T TRGT .Although Figure 1 Although not shown, the driver module 120 may include a user interface having one or more actuators (e.g., buttons, sliders, etc.) for receiving user input, and the control circuitry 124 may be configured to determine the target intensity level L of the light source 110 in response to the actuation of the actuators of the user interface. TRGT Or target color temperature T TRGT .

[0023] The LED driver system 100 may include a memory 128 configured to store operating characteristics (e.g., operating settings, control parameters, operating modes of the LED driver system 100, etc.), association information for association with other devices, and / or instructions for controlling electrical loads. For example, the memory 128 may be configured to store a target intensity level L. TRGT Target color temperature T TRGT Low-end strength level L LE and / or high-end strength level L HE Memory 128 may be implemented as an external integrated circuit (IC) or as internal circuitry of control circuitry 124. Memory 128 may include a computer-readable or machine-readable storage medium that maintains computer-executable instructions for performing one or more processes and / or functions as described herein. For example, memory 128 may include computer-executable or machine-readable instructions that, when executed by control circuitry, configure control circuitry to provide one or more portions of the processes described herein. Control circuitry 124 may access instructions from memory 128 for execution to cause control circuitry 124 to operate as described herein or to operate one or more other means as described herein. Memory 128 may include computer-executable instructions for performing configuration software. For example, operating characteristics and / or associated information stored in memory 128 may be configured during the configuration process of LED driver system 100.

[0024] The LED driver system 100 may include a power supply 129 that can receive a bus voltage V. BUS It also generates a supply voltage V for powering the control circuit 124 of the LED driver system 100 and other low-voltage circuit systems. CC .

[0025] When (for example, according to the strength level L of the command received via communication circuit 126) CMD Determined target intensity level L TRGT Greater than (e.g., greater than or equal to) the threshold intensity level L TH (For example, at approximately 1%), the control circuit 124 can be configured to set the target intensity level L TRGT Set to equal (for example, approximately equal to) the intensity level L of the command. CMD And set the target color temperature T TRGT Set to equal (for example, approximately equal to) the color temperature L of the command. TRGT For example, control circuit 124 can be configured to set the target intensity level L TRGT Set to high strength level L HE With threshold intensity level L THThe number between them is N L The intensity level L closest to the command among the intensity levels CMD A strength level (e.g., by using the strength level L of the command) CMD Rounded to the strength level step size Δ L (the closest multiple). In some examples, the threshold intensity level L TH It can be greater than or less than 1%.

[0026] When the target intensity level L TRGT At low intensity level L LE When nearby (e.g., when the target intensity level L) TRGT Less than the threshold intensity level L TH (At that time), the control circuit 124 may be unable to determine the current color temperature T of the accumulated light emitted by the light source 110. PRES Controlled to the target intensity level L between the first color temperature T1 and the second color temperature T2 TRGT Greater than (e.g., greater than or equal to) the threshold intensity level L TH Each possible color temperature (e.g., since the control circuit 124 can control the first drive signal V) DR1 On-time T ON1 Second drive signal V DR2 On-time T ON2 The minimum step size Δ to be adjusted T-ON (restrictions). Figure 2 Possible operating point 200 is shown, which can be defined at threshold intensity level L. TH The color temperature achieved at the following discrete intensity levels. For example... Figure 2 As shown, the number of possible operating points 200 (e.g., color temperature and corresponding intensity level) that can be achieved at a specific intensity level increases with the current intensity level L. PRES Approaching low-end strength level L LE (For example, by approximately 0.1%). At the low-end strength level L LE Below, the control circuit 124 can be configured to control the current color temperature T of the light emitted by the light source 110 by only turning on the first emitter circuit 111. PRES The light emitted by the light source is controlled to a first color temperature T1, and the current color temperature is controlled to a second color temperature T2 by only turning on the second emitter circuit 112. Additionally, at the low intensity level L... LE Below, the control circuit 124 can be configured to control the current color temperature T of the light emitted by the light source 110. PRES A third color temperature T3 (e.g., midpoint color temperature) is controlled between the first color temperature T1 and the second color temperature T2. For example, the third color temperature T3 could be approximately 2400 K. At the low-end intensity level L... LEAt the third color temperature T3, the control circuit 124 can transmit the first drive signal V DR1 On-time T ON1 Second drive signal V DR2 On-time T ON2 Both are controlled to the minimum conduction time T ON-MIN In other words, when ordered to enter a low-end intensity level L LE At this time, the control circuit 123 can be configured to control the accumulated light emitted by the light source 110 to only one of the three color temperatures. In some examples, when commanded to enter the low-end intensity level L LE In this case, the control circuit 123 can be configured to control the accumulated light emitted by the light source 110 to only one of two color temperatures (e.g., a first color temperature T1 and a second color temperature T2).

[0027] When the target intensity level L TRGT Less than the threshold intensity level L TH At that time, the control circuit 124 can be configured to set the target intensity level L TRGT Set to equal (for example, approximately equal to) the intensity level L of the command. CMD (For example, with the target intensity level L) TRGT Greater than the threshold intensity level L TH (Set in the same way as before). Additionally, when the target intensity level L... TRGT Less than the threshold intensity level L TH At that time, the control circuit 124 can be configured to make the target color temperature T TRGT With the target intensity level L TRGT Lowering and moving towards lower strength levels L LE One or more of the possible color temperatures (e.g., first color temperature, second color temperature, and third color temperatures T1, T2, T3) converge. For example, when the target intensity level L TRGT Less than the threshold intensity level L TH At this time, the control circuit 124 can be configured to limit the target color temperature T according to one or more limit curves. TRGT The one or more limiting curves can allow the target color temperature T TRGT With the target intensity level L TRGT Lowering and moving towards lower strength levels L LE One or more of the possible color temperatures will converge. Target color temperature T TRGT The low-end intensity level L that can converge towards it LE One or more of the possible color temperatures can depend on the color temperature T of the command. CMD Set the target color temperature T. TRGT With the target intensity level L TRGT Towards low-end strength level L LELowering the color temperature and converging towards one or more color temperatures can achieve the target color temperature T. TRGT The changes are subtle and not easily noticeable, especially at low intensity levels L. LE Smooth dimming is provided nearby.

[0028] Figure 3 Several examples of constraint curves 300 and 310 are shown, which are used to define the target intensity level L of the light source (e.g., light source 110). TRGT Less than the threshold intensity level L TH The target color temperature T of the light source TRGT Adjustments. For example, when the target intensity level L... TRGT Less than the threshold intensity level L TH At that time, it can be controlled by the driver module's control circuit (e.g., such as...). Figure 1 The control circuit 124 of the driver module 120 of the LED driver system 100 shown is based on... Figure 3 The limiting curves 300 and 310 shown are used to adjust the target color temperature T of the light source. TRGT .like Figure 3 As shown, the control circuit can be configured to make the target color temperature T TRGT With the target intensity level L TRGT Towards low-end strength level L LE The color temperature decreases and converges towards one of the two color temperatures (e.g., a first color temperature T1 and a second color temperature T2). Target color temperature T TRGT One of the two color temperatures that can converge to it depends on the commanded color temperature T. CMD (For example, the color temperature T depends on the command) CMD Is it greater than or less than the threshold color temperature T? TH For example, threshold color temperature T TH It can be approximately equal to the third color temperature T3 (e.g., approximately 2400 K).

[0029] When the color temperature of the command is T CMD Color temperature greater than (e.g., greater than or equal to) the threshold color temperature T TH At that time, the control circuit can be configured to limit the target color temperature T of the light source according to the first limiting curve 300. TRGT At the target intensity level L TRGT At a specific value, when the color temperature T of the command is... CMD Color temperature greater than (e.g., greater than or equal to) the threshold color temperature T TH At this time, the control circuit may not set the target color temperature T. TRGT Set it to be less than the first limit curve 300. For example, the first limit curve 300 can define the target color temperature T. TRGT With target intensity level L TRGTA linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The third color temperature T3 extends to the low-end intensity level L. LE The first color temperature T1 is defined. In some examples, the first limiting curve 300 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The third color temperature T3 extends to the low-end intensity level L. LE The first color temperature T1 is determined by the first limiting curve 300, which can result in the target color temperature T of the light source. TRGT With the target intensity level L TRGT Towards low-end strength L LE They converge towards the first color temperature T1 as they decrease in color temperature.

[0030] When the color temperature of the command is T CMD Color temperature less than threshold T TH At this time, the control circuit can be configured to limit the target color temperature T of the light source according to the second limiting curve 310. TRGT At the target intensity level L TRGT At a specific value, when the color temperature T of the command is... CMD Color temperature less than threshold T TH At this time, the control circuit may not set the target color temperature T. TRGT Set to be greater than the second limiting curve 310. For example, the second limiting curve 310 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The third color temperature T3 extends to the low-end intensity level L. LE The second color temperature T2 is specified below. In some examples, the second limiting curve 310 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The third color temperature T3 extends to the low-end intensity level L. LE The second color temperature T2 is below. The second limiting curve 310 can cause the target color temperature T of the light source to be... TRGT With the target intensity level L TRGT Towards low-end strength L LE They converge towards the second color temperature T2 as they decrease in color temperature.

[0031] Figure 4Limiting curves 410, 420, 430, and 440 are shown. These limiting curves are used to define the target intensity level L of the light source (e.g., light source 110). TRGT Less than the threshold intensity level L TH The target color temperature T of the light source TRGT Adjustments. For example, when the target intensity level L... TRGT Less than the threshold intensity level L TH At that time, it can be controlled by the driver module's control circuit (e.g., such as...). Figure 1 The control circuit 124 of the driver module 120 of the LED driver system 100 shown is based on... Figure 4 The limiting curves 410, 420, 430, and 440 shown are used to adjust the target color temperature T of the light source. TRGT .like Figure 4 As shown, the control circuit can be configured to make the target color temperature T TRGT With target intensity level LT RGT Towards low-end strength level L LE The color temperature decreases and converges towards one of the three color temperatures (e.g., first color temperature T1, second color temperature T2, and third color temperature T3). Target color temperature T TRGT One of the three color temperatures that can converge to it depends on the commanded color temperature T. CMD (For example, the color temperature T depends on the command) CMD Is it greater than or less than the two threshold color temperatures T? TH1 T TH2 (A threshold color temperature). For example, the first threshold color temperature T TH1 It can be approximately 2800 K, and the second threshold color temperature T TH2 It can be approximately 2000 K.

[0032] When the color temperature of the command is T CMD Color temperature greater than (e.g., greater than or equal to) the first threshold T TH1 At that time, the control circuit can be configured to limit the target color temperature T of the light source according to the first limiting curve 410. TRGT At the target intensity level L TRGT At a specific value, when the color temperature T of the command is... CMD Color temperature greater than (e.g., greater than or equal to) the first threshold T TH1 At this time, the control circuit may not set the target color temperature T. TRGT Set to be less than the first limiting curve 410. For example, the first limiting curve 410 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The range extends from approximately 2800k to the low-end strength level L.LE The first color temperature T1 is defined. In some examples, the first limiting curve 410 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The range extends from approximately 2800 k to the lower end of the strength level L. LE The first color temperature T1 is determined by the first limiting curve 410, which can result in a target color temperature T of the light source. TRGT With the target intensity level L TRGT Towards low-end strength L LE They converge towards the first color temperature T1 as they decrease in color temperature.

[0033] When the color temperature of the command is T CMD Color temperature T less than the second threshold TH2 At this time, the control circuit can be configured to limit the target color temperature T of the light source according to the fourth limiting curve 440. TRGT At the target intensity level L TRGT At a specific value, when the color temperature T of the command is... CMD Color temperature T less than the second threshold TH2 At this time, the control circuit may not set the target color temperature T. TRGT Set it to be greater than the fourth limit curve 440. For example, the fourth limit curve 440 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The range extends from approximately 2000 k to the low-end strength level L. LE The second color temperature T2 is specified below. In some examples, the fourth limiting curve 440 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The range extends from approximately 2000 k to the low-end strength level L. LE The second color temperature T2 is below. The fourth limiting curve 440 can result in the target color temperature T of the light source. TRGT With the target intensity level L TRGT Towards low-end strength L LE They converge towards the second color temperature T2 as they decrease in color temperature.

[0034] When the color temperature of the command is T CMD First threshold color temperature T TH1 With the second threshold color temperature T TH2In between, the control circuit can be configured to limit the target color temperature T of the light source according to the second limiting curve 420 and the third limiting curve 430. TRGT The second constraint curve 420 and the third constraint curve 430 can result in the target color temperature T of the light source. TRGT With the target intensity level L TRGT Towards low-end strength L LE They converge towards the third color temperature, T3, as they decrease in color temperature.

[0035] When the color temperature of the command is T CMD Color temperature T less than the first threshold TH1 And greater than (e.g., greater than or equal to) the third threshold color temperature T TH3 At this time, the control circuit can be configured to limit the target color temperature T of the light source according to the second limiting curve 420. TRGT For example, the third threshold color temperature T TH3 This can be approximately equal to the third color temperature T3 (e.g., approximately 2400 K). At the target intensity level L... TRGT At a specific value, when the color temperature T of the command is... CMD Color temperature T less than the first threshold TH1 And greater than (e.g., greater than or equal to) the third threshold color temperature T TH3 At this time, the control circuit may not set the target color temperature T. TRGT Set it to be greater than the second limit curve 420. For example, the second limit curve 420 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The range extends from approximately 2800 k to the lower end of the strength level L. LE The third color temperature T3 is specified below. In some examples, the second limiting curve 420 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The range extends from approximately 2800 k to the lower end of the strength level L. LE The third color temperature, T3.

[0036] When the color temperature of the command is T CMD Color temperature T less than the third threshold TH3 And greater than (e.g., greater than or equal to) the second threshold color temperature T TH2 At this time, the control circuit can be configured to limit the target color temperature T of the light source according to the third limiting curve 430. TRGT At the target intensity level L TRGT At a specific value, when the color temperature T of the command is... CMDColor temperature T less than the third threshold TH3 And greater than (e.g., greater than or equal to) the second threshold color temperature T TH2 At this time, the control circuit may not set the target color temperature T. TRGT Set it to be less than the third limit curve 430. For example, the third limit curve 430 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The range extends from approximately 2000 k to the low-end strength level L. LE The third color temperature T3 is specified below. In some examples, the third limiting curve 430 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The range extends from approximately 2000 k to the low-end strength level L. LE The third color temperature, T3.

[0037] Figure 5 Limiting curves 510, 520, 530, and 540 are shown, which are used to define the target intensity level L of the light source (e.g., light source 110). TRGT Less than the threshold intensity level L TH The target color temperature T of the light source TRGT Adjustments. For example, when the target intensity level L... TRGT Less than the threshold intensity level L TH At that time, it can be controlled by the driver module's control circuit (e.g., such as...). Figure 1 The control circuit 124 of the driver module 120 of the LED driver system 100 shown is based on... Figure 5 The limiting curves 510, 520, 530, and 540 shown are used to adjust the target color temperature T of the light source. TRGT .like Figure 5 As shown, the control circuit can be configured to make the target color temperature T TRGT With target intensity level LT RGT Towards low-end strength level L LE The color temperature decreases and converges towards one of the three color temperatures (e.g., first color temperature T1, second color temperature T2, and third color temperature T3). Target color temperature T TRGT One of the three color temperatures that can converge to it depends on the commanded color temperature T. CMD (For example, the color temperature T depends on the command) CMD Is it greater than or less than the two threshold color temperatures T? TH1 T TH2 (A threshold color temperature). For example, the first threshold color temperature TTH1 It can be approximately 2800 K, and the second threshold color temperature T TH2 It can be approximately 2000 K.

[0038] according to Figure 5 The limiting curves 510, 520, 530, and 540 shown indicate that the control circuit can be configured to make the target color temperature T... TRGT With the target intensity level L TRGT Towards low-end strength level L LE Reduce and move towards cross-target intensity level L TRGT One of the three color temperatures within a smaller range will converge (e.g., as when the control circuit uses...). Figure 4 (Compared to the constraint curves 410, 420, 430, and 440 shown). Each of the constraint curves 510, 520, 530, and 540 can define a threshold intensity level L. TH With intermediate strength level L INT The linear region between, where the target color temperature T TRGT Relative to target intensity level L TRGT It is variable. When the target color temperature L TRGT Less than the intermediate strength level L INT At that time, the target color temperature T TRGT It can be kept constant at one of the three color temperatures (e.g., the first color temperature T1, the second color temperature T2, or the third color temperature T3).

[0039] When the color temperature of the command is T CMD Color temperature greater than (e.g., greater than or equal to) the first threshold T TH1 At that time, the control circuit can be configured to limit the target color temperature T of the light source according to the first limiting curve 510. TRGT At the target intensity level L TRGT At a specific value, when the color temperature T of the command is... CMD Color temperature greater than (e.g., greater than or equal to) the first threshold T TH1 At this time, the control circuit may not set the target color temperature T. TRGT Set to be less than the first limiting curve 510. For example, the first limiting curve 510 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The range extends from approximately 2800k to the intermediate strength level L. INT The first color temperature T1 is defined. In some examples, the first limiting curve 510 can define the target color temperature T. TRGT With target intensity level L TRGTThe nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The range extends from approximately 2800 k to the intermediate intensity level L. INT The first color temperature T1 is determined by the first limiting curve 510, which can result in a target color temperature T of the light source. TRGT With the target intensity level L TRGT Towards intermediate strength level L INT It decreases and converges towards the first color temperature T1. At the intermediate intensity level L... INT Hereinafter, the first limiting curve 510 can be equal to the first color temperature T1.

[0040] When the color temperature of the command is T CMD Color temperature T less than the second threshold TH2 At this time, the control circuit can be configured to limit the target color temperature T of the light source according to the fourth limiting curve 540. TRGT At the target intensity level L TRGT At a specific value, when the color temperature T of the command is... CMD Color temperature T less than the second threshold TH2 At this time, the control circuit may not set the target color temperature T. TRGT Set it to be greater than the fourth limit curve 540. For example, the fourth limit curve 540 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The range extends from approximately 2000 k to the intermediate intensity level L. INT The second color temperature T2 is specified below. In some examples, the fourth limiting curve 540 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The range extends from approximately 2000k to the intermediate strength level L. INT The second color temperature T2 is below. The fourth limiting curve 540 can result in the target color temperature T of the light source. TRGT With the target intensity level L TRGT Towards intermediate strength level L INT It decreases and converges towards the second color temperature T2. At the intermediate intensity level L... INT Below, the fourth limiting curve 540 can be equal to the second color temperature T2.

[0041] When the color temperature of the command is T CMD First threshold color temperature T TH1 With the second threshold color temperature T TH2In between, the control circuit can be configured to limit the target color temperature T of the light source according to the second limiting curve 520 and the third limiting curve 530. TRGT The second constraint curve 520 and the third constraint curve 530 can result in the target color temperature T of the light source. TRGT With the target intensity level L TRGT Towards intermediate strength level L INT They converge towards the third color temperature, T3, as they decrease in color temperature.

[0042] When the color temperature of the command is T CMD Color temperature T less than the first threshold TH1 And greater than (e.g., greater than or equal to) the third threshold color temperature T TH3 At that time, the control circuit can be configured to limit the target color temperature T of the light source according to the second limiting curve 520. TRGT For example, the third threshold color temperature T TH3 This can be approximately equal to the third color temperature T3 (e.g., approximately 2400 K). At the target intensity level L... TRGT At a specific value, when the color temperature T of the command is... CMD Color temperature T less than the first threshold TH1 And greater than (e.g., greater than or equal to) the third threshold color temperature T TH3 At this time, the control circuit may not set the target color temperature T. TRGT Set it to be greater than the second limit curve 520. For example, the second limit curve 420 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The range extends from approximately 2800 k to the intermediate intensity level L. INT The third color temperature T3 is specified below. In some examples, the second limiting curve 520 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The range extends from approximately 2800 k to the intermediate intensity level L. INT The third color temperature T3 is below. At the intermediate intensity level L... INT Below, the second limiting curve 520 can be equal to the third color temperature T3.

[0043] When the color temperature of the command is T CMD Color temperature T less than the third threshold TH3 And greater than (e.g., greater than or equal to) the second threshold color temperature T TH2 At this time, the control circuit can be configured to limit the target color temperature T of the light source according to the third limiting curve 530. TRGT At the target intensity level LTRGT At a specific value, when the color temperature T of the command is... CMD Color temperature T less than the third threshold TH3 And greater than (e.g., greater than or equal to) the second threshold color temperature T TH2 At this time, the control circuit may not set the target color temperature T. TRGT Set it to be less than the third limit curve 530. For example, the third limit curve 530 can define the target color temperature T. TRGT With target intensity level L TRGT A linear relationship (e.g., a line) between the threshold intensity level L and the threshold intensity level L. TH The range extends from approximately 2000 k to the intermediate intensity level L. INT The third color temperature T3 is specified below. In some examples, the third limiting curve 420 can define the target color temperature T. TRGT With target intensity level L TRGT The nonlinear relationship between them (e.g., having a curved shape and / or an exponential shape), which starts from the threshold intensity level L TH The range extends from approximately 2000 k to the intermediate intensity level L. INT The third color temperature T3 is below. At the intermediate intensity level L... INT Below, the third limiting curve 530 can be equal to the third color temperature T3.

[0044] Figure 6 It is used to adjust the target color temperature T of the light source (e.g., light source 110). TRGT The flowchart of example process 600 is shown. Process 600 may be controlled by the control circuitry of a driver module (e.g., such as...). Figure 1 The control circuit 124 of the driver module 120 of the LED driver system 100 shown is executed. The light source may include light sources configured to emit light at a first color temperature. T1 The first emitter circuit of light (e.g., the first LED circuit) is configured to emit light at a second color temperature. T2 A second light emitter circuit (e.g., a second LED circuit). The control circuit can be configured to generate a first drive signal V. DR1 A first LED driving circuit is used to control the intensity level of the first transmitter circuit and to generate a second driving signal V. DR2 A second LED driver circuit is used to control the intensity level of the second emitter circuit. The control circuit can adjust the intensity levels of the first and second emitter circuits of the light source to control the current intensity level L of the accumulated light emitted by the light source. PRES and the current color temperature T PRESFor example, the control circuit can periodically execute process 600 at 610. Additionally, the control circuit can execute process 600 at 610 in response to receiving a message via a communication circuit (e.g., communication circuit 126) and / or in response to actuation of an actuator in the driver module.

[0045] At position 612, the control circuit can receive the command strength level L. CMD and / or command color temperature T CMD For example, the control circuit can receive the command strength level L in a message received via the communication circuit. CMD and / or command color temperature T CMD At point 614, the control circuit can respond to the command strength level L. CMD And determine the target intensity level L TRGT For example, the control circuit can be configured to control the first LED driver circuit and the second LED driver circuit to move towards the target intensity level L. TRGT Control the current intensity level L of the cumulative light emitted by the light source. PRES The control circuit can be configured to set the target intensity level L TRGT Set to high strength level L HE Compared with low-end strength level L LE The number between them is N L The intensity level L closest to the command among the intensity levels CMD A strength level (e.g., by using the strength level L of the command) CMD Rounded to the strength level step size Δ L (the closest multiple).

[0046] At point 616, the control circuit can determine the target intensity level L. TRGT Is it less than the threshold intensity level L? TH (For example, at the low-end strength level L) LE (Nearby). When the target intensity level L is at 616. TRGT Greater than (e.g., greater than or equal to) the threshold intensity level L TH At that time, the control circuit can set the target color temperature T at 618. TRGT Set to equal (for example, approximately equal to) the color temperature T of the command. CMD When the target intensity level L is at 616... TRGT Less than the threshold intensity level L TH At that time, the control circuit can be set to a color temperature L based on the command at 620. CMD To select one or more limiting curves. The control circuit can select, for example... Figure 3 One of the two limiting curves 300 and 310 is shown. For example, the control circuit can be set to a color temperature L. CMD Color temperature greater than threshold TTH When selecting one of the first limiting curves 300, and when the color temperature of the command is less than the threshold color temperature T TH The second limiting curve 310 is selected at this time. Alternatively, the control circuit can select, for example... Figure 4 One or more of the four limiting curves 410, 420, 430, and 440 shown. Figure 5 One of the four limiting curves shown: 510, 520, 530, and 540.

[0047] At position 622, the control circuit can determine the color temperature T of the command. CMD Does it exceed one of the limit curves selected at 620? For example, when the color temperature of the command is... Figures 3-5 When the selected limiting curve is to the left, the control circuit can determine the commanded color temperature T. CMD Exceeding one of the limit curves. When the commanded color temperature L CMD Color temperature greater than threshold T TH For example, the control circuit can set the color temperature L in the command. CMD Less than the target intensity level L TRGT The first limiting curve 300 below (e.g., as Figure 3 (As shown) Determine the color temperature T of the command. CMD Exceeding the first limit curve of 300. When the commanded color temperature L CMD Color temperature less than threshold T TH For example, the control circuit can set the color temperature L in the command. CMD Greater than the target intensity level L TRGT The second limiting curve 310 below (e.g., as shown) Figure 3 (As shown) Determine the color temperature T of the command. CMD The second limit curve 310 is exceeded. The control circuit can similarly determine the commanded color temperature T. CMD It has exceeded the limit curve 410-440 (e.g., as shown in the image). Figure 4 (as shown) and limiting curves 510-540 (e.g., as shown) Figure 5 (As shown).

[0048] When the control circuit determines the color temperature T of the command at 622. CMD When the selected limit curve is not exceeded, the control circuit can set the target color temperature T at 618. TRGT Set to equal (for example, approximately equal to) the color temperature T of the command. CMD When the control circuit determines the commanded color temperature T at 622. CMD When the selected limit curve is exceeded, the control circuit can limit the target color temperature T at point 624 based on the limit curve. TRGT For example, the control circuit can control the target color temperature T. TRGTSet to equal to the target intensity level L TRGT (For example, as determined at 614) the value of the restricted color temperature on the selected limiting curve. When the commanded color temperature L CMD Color temperature greater than threshold T TH At that time, the control circuit can set the target color temperature T. TRGT Set to, for example, target intensity level L TRGT The restricted color temperature value on the first limiting curve 300 below. When the commanded color temperature L CMD Color temperature less than threshold T TH At that time, the control circuit can set the target color temperature T. TRGT Set to, for example, target intensity level L TRGT The restricted color temperature value on the second limiting curve 310 below. The control circuit can similarly set the target color temperature T. TRGT Set it to equal the limit curve 410-440 (e.g., as shown below) Figure 4 (as shown) and limiting curves 510-540 (e.g., as shown) Figure 5 The restricted color temperature value shown.

[0049] When the target color temperature T is set at 618 or 624... TRGT Then, the control circuit can determine at 626 the current color temperature T of the light emitted by the light source. PRES Controlled to the target color temperature T TRGT The corresponding drive signal V DR1 V DR2 The duty cycles d1 and d2. For example, the control circuit 124 can be configured based on the target color temperature T. TRGT To calculate the corresponding driving signal V DR1 V DR2 The duty cycles d1 and d2. At 628, the control circuit can be based on the target intensity level L. TRGT And such as based on target color temperature T TRGT The corresponding drive signal V is calculated based on the determined duty cycles d1 and d2. DR1 V DR2 Expected conduction time T ON1-D T ON2-D (For example, T) ON1-D = d1·L TRGT · T OP And T ON2-D = d2· L TRGT · T OP At 630, the control circuit can adjust the desired on-time T. ON1-D T ON2-D Each expected conduction time in the range is rounded up to the minimum step size Δ. T-ONThe closest multiple is used to determine the corresponding drive signal V DR1 V DR2 On-time T ON1 , TON2 Round down to the minimum step size Δ T-ON The closest multiple allows the control circuit to adjust the current color temperature T. PRES Controlled to the target intensity level L TRGT The target color temperature T TRGT The closest operating point (e.g., Figure 2 (One of the operating points 200 shown). At 632, the control circuit can use the corresponding on-time T. ON1 , TON2 To generate drive signals VDR1 , VDR2 To control the accumulated light emitted by the light source to the target intensity level L. TRGT and target color temperature T TRGT .

Claims

1. A load control device for controlling the amount of power delivered to a light source, the light source having a first emitter circuit configured to emit light having a first color temperature and a second emitter circuit configured to emit light having a second color temperature, the load control device comprising: A first driving circuit, configured to control a first intensity level of the first transmitter circuit; A second driving circuit, configured to control a second intensity level of the second transmitter circuit; as well as A control circuit configured to control the first drive circuit and the second drive circuit to adjust the first intensity level of the first emitter circuit and the second intensity level of the second emitter circuit so that the current intensity level and current color temperature of the accumulated light emitted by the light source are respectively controlled toward the target intensity level and the target color temperature. When the target intensity level is less than a threshold intensity level, the control circuit is configured to limit the target color temperature according to at least one limiting curve, the at least one limiting curve causing the target color temperature to converge toward at least one of a first color temperature or a second color temperature as the target intensity level decreases toward a lower intensity level.

2. The load control device as claimed in claim 1, wherein the control circuit is configured to: Receives a color temperature for controlling the accumulated light emitted by the light source; When the color temperature of the command is greater than a threshold color temperature, the target color temperature is limited according to a first limiting curve, which causes the target color temperature to converge toward the first color temperature as the target intensity level decreases toward the lower end of the intensity level; and When the color temperature of the command is less than the threshold color temperature, the target color temperature is limited according to the second limiting curve, which causes the target color temperature to converge toward the second color temperature as the target intensity level decreases toward the low-end intensity level.

3. The load control device of claim 2, wherein the control circuit is configured to: When the color temperature of the command exceeds the first limiting curve, the target color temperature converges towards the first color temperature as the target intensity level decreases towards the lower intensity level by setting the target color temperature to a value equal to the first limited color temperature on the first limiting curve at the target intensity level; and When the color temperature of the command exceeds the second limiting curve, the target color temperature converges toward the second color temperature as the target intensity level decreases toward the lower intensity level by setting the target color temperature to a value equal to the second limited color temperature on the second limiting curve at the target intensity level.

4. The load control device of claim 3, wherein the control circuit is configured to: When the color temperature of the command is greater than the threshold color temperature and the color temperature of the command does not exceed the first limiting curve, the target color temperature is set to be equal to the color temperature of the command; and When the color temperature of the command is less than the threshold color temperature and the color temperature of the command does not exceed the second limit curve, the target color temperature is set to be equal to the color temperature of the command.

5. The load control device of claim 3, wherein the control circuit is configured to: When the color temperature of the command is greater than the threshold color temperature and the color temperature of the command is less than the first limiting curve at the target intensity level, it is determined that the color temperature of the command exceeds the first limiting curve; and When the color temperature of the command is less than the threshold color temperature and the color temperature of the command is less than the second limit curve at the target intensity level, it is determined that the color temperature of the command exceeds the second limit curve.

6. The load control device as claimed in claim 2, further comprising: A communication circuit configured to receive messages; The control circuit is configured to receive a message including the color temperature of the command.

7. The load control device of claim 1, wherein the control circuit is configured to: Receives a color temperature for controlling the accumulated light emitted by the light source; When the color temperature of the command is greater than the first threshold color temperature, the target color temperature is limited according to the first limiting curve. The first limiting curve causes the target color temperature to converge toward the first color temperature as the target intensity level decreases toward the low-end intensity level. When the color temperature of the command is less than the second threshold color temperature, the target color temperature is limited according to the second limiting curve, which causes the target color temperature to converge toward the second color temperature as the target intensity level decreases toward the lower end of the intensity level; and When the color temperature of the command is between the first threshold color temperature and the second threshold color temperature, the target color temperature is limited according to the third limiting curve and the fourth limiting curve, which cause the target color temperature to converge toward the third color temperature as the target intensity level decreases toward the lower intensity level, wherein the third color temperature is between the first color temperature and the second color temperature.

8. The load control device of claim 7, wherein the control circuit is configured to: When the color temperature of the command exceeds the first limiting curve, the target color temperature converges toward the first color temperature as the target intensity level decreases toward the lower intensity level by setting the target color temperature to the value of the first restricted color temperature on the first limiting curve at the target intensity level. When the color temperature of the command exceeds the second limiting curve, the target color temperature converges toward the second color temperature as the target intensity level decreases toward the lower intensity level by setting the target color temperature to a value equal to the second restricted color temperature on the second limiting curve at the target intensity level; and The target color temperature converges toward the third color temperature as the target intensity level decreases toward the lower intensity level by: setting the target color temperature to equal the value of the third restricted color temperature on the third restriction curve at the target intensity level when the color temperature of the command is greater than the third threshold color temperature and the color temperature of the command exceeds the third restriction curve; and setting the target color temperature to equal the value of the fourth restricted color temperature on the fourth restriction curve at the target intensity level when the color temperature of the command is less than the third threshold color temperature and the color temperature of the command exceeds the fourth restriction curve.

9. The load control device of claim 7, wherein the control circuit is configured to converge the target color temperature toward the first color temperature, the second color temperature and the third color temperature when the target intensity level is equal to or less than the threshold intensity level and greater than the low-end intensity level.

10. The load control device of claim 1, wherein the control circuit is configured to: Generate a first drive signal and a second drive signal to control the first drive circuit and the second drive circuit, respectively. The corresponding on-time of the first driving signal and the second driving signal is determined in response to the target intensity level and the target color temperature; as well as The control circuit can adjust the corresponding conduction times of the first drive signal and the second drive signal with the minimum step size by rounding the corresponding conduction times of the first drive signal and the second drive signal to a multiple of the minimum step size.

11. A method for controlling an electrical force delivered to a light source, the light source having a first emitter circuit configured to emit light having a first color temperature and a second emitter circuit configured to emit light having a second color temperature, the method comprising: The first driving circuit is controlled to control the first intensity level of the first transmitter circuit; The second drive circuit is controlled to control the second intensity level of the second transmitter circuit; The first driving circuit and the second driving circuit are controlled to control the current intensity level and current color temperature of the accumulated light emitted by the light source toward the target intensity level and target color temperature, respectively. as well as When the target intensity level is less than the threshold intensity level, the target color temperature is limited according to at least one limiting curve, the at least one limiting curve causing the target color temperature to converge toward at least one of a first color temperature or a second color temperature as the target intensity level decreases toward a lower intensity level.

12. The method of claim 11, further comprising: The color temperature is received as a command to control the accumulated light emitted by the light source.

13. The method of claim 12, wherein limiting the target color temperature further comprises: When the color temperature of the command is greater than the threshold color temperature, the target color temperature is limited according to the first limiting curve. The first limiting curve causes the target color temperature to converge toward the first color temperature as the target intensity level decreases toward the low-end intensity level. as well as When the color temperature of the command is less than the threshold color temperature, the target color temperature is limited according to the second limiting curve, which causes the target color temperature to converge toward the second color temperature as the target intensity level decreases toward the low-end intensity level.

14. The method of claim 13, wherein limiting the target color temperature according to the first limiting curve further comprises: When the color temperature of the command exceeds the first limiting curve, the target color temperature is set to be equal to the value of the first limited color temperature on the first limiting curve at the target intensity level; and The limitation of the target color temperature according to the second limitation curve further includes: when the color temperature of the command exceeds the second limitation curve, setting the target color temperature to a value equal to the second limited color temperature on the second limitation curve at the target intensity level.

15. The method of claim 14, further comprising: When the color temperature of the command is greater than the threshold color temperature and the color temperature of the command does not exceed the first limiting curve, the target color temperature is set to be equal to the color temperature of the command. as well as When the color temperature of the command is less than the threshold color temperature and the color temperature of the command does not exceed the second limit curve, the target color temperature is set to be equal to the color temperature of the command.

16. The method of claim 14, further comprising: When the color temperature of the command is greater than the threshold color temperature and the color temperature of the command is less than the first limiting curve at the target intensity level, it is determined that the color temperature of the command exceeds the first limiting curve; and When the color temperature of the command is less than the threshold color temperature and the color temperature of the command is less than the second limit curve at the target intensity level, it is determined that the color temperature of the command exceeds the second limit curve.

17. The load control device of claim 12, wherein limiting the target color temperature further comprises: When the color temperature of the command is greater than the first threshold color temperature, the target color temperature is limited according to the first limiting curve. The first limiting curve causes the target color temperature to converge toward the first color temperature as the target intensity level decreases toward the low-end intensity level. When the color temperature of the command is less than the second threshold color temperature, the target color temperature is limited according to the second limiting curve, which causes the target color temperature to converge toward the second color temperature as the target intensity level decreases toward the low-end intensity level; as well as When the color temperature of the command is between the first threshold color temperature and the second threshold color temperature, the target color temperature is limited according to the third limiting curve and the fourth limiting curve, which cause the target color temperature to converge toward the third color temperature as the target intensity level decreases toward the lower intensity level, wherein the third color temperature is between the first color temperature and the second color temperature.

18. The method of claim 17, further comprising: When the target intensity level is equal to or less than the threshold intensity level and greater than the low-end intensity level, the target color temperature converges towards the first color temperature, the second color temperature and the third color temperature.

19. The method of claim 12, further comprising: Receive a message including the color temperature of the command.

20. The method of claim 11, further comprising: Generate a first drive signal and a second drive signal to control the first drive circuit and the second drive circuit, respectively. The corresponding on-time of the first driving signal and the second driving signal is determined in response to the target intensity level and the target color temperature; as well as The control circuit can adjust the corresponding conduction times of the first drive signal and the second drive signal with the minimum step size by rounding the corresponding conduction times of the first drive signal and the second drive signal to a multiple of the minimum step size.

21. A load control device for controlling the amount of power delivered to a light source, the light source having a plurality of emitter circuits, each of the plurality of emitter circuits being configured to emit light at a corresponding color temperature, the load control device comprising: Multiple driving circuits, each of which is configured to control a corresponding intensity level of one of the multiple emitter circuits of the light source; as well as A control circuit configured to control each of the plurality of drive circuits to adjust the corresponding intensity level of each of the emitter circuits so that the current intensity level and current color temperature of the accumulated light emitted by the light source are controlled toward a target intensity level and a target color temperature, respectively. When the target intensity level is less than a threshold intensity level, the control circuit is configured to limit the target color temperature according to at least one limiting curve, the at least one limiting curve causing the target color temperature to converge toward at least one of a first color temperature or a second color temperature as the target intensity level decreases toward a lower intensity level.

22. The load control device of claim 21, wherein the control circuit is configured to: Receives a color temperature for controlling the accumulated light emitted by the light source; When the color temperature of the command is greater than a threshold color temperature, the target color temperature is limited according to a first limiting curve, which causes the target color temperature to converge toward the first color temperature as the target intensity level decreases toward the lower end of the intensity level; and When the color temperature of the command is less than the threshold color temperature, the target color temperature is limited according to the second limiting curve, which causes the target color temperature to converge toward the second color temperature as the target intensity level decreases toward the low-end intensity level.

23. The load control device of claim 22, wherein the control circuit is configured to: When the color temperature of the command exceeds the first limiting curve, the target color temperature converges towards the first color temperature as the target intensity level decreases towards the lower intensity level by setting the target color temperature to a value equal to the first limited color temperature on the first limiting curve at the target intensity level; and When the color temperature of the command exceeds the second limiting curve, the target color temperature converges toward the second color temperature as the target intensity level decreases toward the lower intensity level by setting the target color temperature to a value equal to the second limited color temperature on the second limiting curve at the target intensity level.

24. The load control device of claim 23, wherein the control circuit is configured to: When the color temperature of the command is greater than the threshold color temperature and the color temperature of the command does not exceed the first limiting curve, the target color temperature is set to be equal to the color temperature of the command; and When the color temperature of the command is less than the threshold color temperature and the color temperature of the command does not exceed the second limit curve, the target color temperature is set to be equal to the color temperature of the command.

25. The load control device of claim 23, wherein the control circuit is configured to: When the color temperature of the command is greater than the threshold color temperature and the color temperature of the command is less than the first limiting curve at the target intensity level, it is determined that the color temperature of the command exceeds the first limiting curve; and When the color temperature of the command is less than the threshold color temperature and the color temperature of the command is less than the second limit curve at the target intensity level, it is determined that the color temperature of the command exceeds the second limit curve.

26. The load control device of claim 22, further comprising: A communication circuit configured to receive messages; The control circuit is configured to receive a message including the color temperature of the command.

27. The load control device of claim 21, wherein the control circuit is configured to: Receives a color temperature for controlling the accumulated light emitted by the light source; When the color temperature of the command is greater than the first threshold color temperature, the target color temperature is limited according to the first limiting curve. The first limiting curve causes the target color temperature to converge toward the first color temperature as the target intensity level decreases toward the low-end intensity level. When the color temperature of the command is less than the second threshold color temperature, the target color temperature is limited according to the second limiting curve, which causes the target color temperature to converge toward the second color temperature as the target intensity level decreases toward the lower end of the intensity level; and When the color temperature of the command is between the first threshold color temperature and the second threshold color temperature, the target color temperature is limited according to the third limiting curve and the fourth limiting curve, which cause the target color temperature to converge toward the third color temperature as the target intensity level decreases toward the lower intensity level, wherein the third color temperature is between the first color temperature and the second color temperature.

28. The load control device of claim 27, wherein the control circuit is configured to: When the color temperature of the command exceeds the first limiting curve, the target color temperature converges toward the first color temperature as the target intensity level decreases toward the lower intensity level by setting the target color temperature to the value of the first restricted color temperature on the first limiting curve at the target intensity level. When the color temperature of the command exceeds the second limiting curve, the target color temperature converges toward the second color temperature as the target intensity level decreases toward the lower intensity level by setting the target color temperature to a value equal to the second restricted color temperature on the second limiting curve at the target intensity level; and The target color temperature converges toward the third color temperature as the target intensity level decreases toward the lower intensity level by: setting the target color temperature to equal the value of the third restricted color temperature on the third restriction curve at the target intensity level when the color temperature of the command is greater than the third threshold color temperature and the color temperature of the command exceeds the third restriction curve; and setting the target color temperature to equal the value of the fourth restricted color temperature on the fourth restriction curve at the target intensity level when the color temperature of the command is less than the third threshold color temperature and the color temperature of the command exceeds the fourth restriction curve.

29. The load control device of claim 27, wherein the control circuit is configured to converge the target color temperature toward the first color temperature, the second color temperature and the third color temperature when the target intensity level is equal to or less than the threshold intensity level and greater than the low-end intensity level.

30. The load control device of claim 21, wherein the control circuit is configured to: Generate multiple drive signals for controlling the multiple drive circuits; The corresponding on-time of the plurality of driving signals is determined in response to the target intensity level and the target color temperature; and The control circuit can adjust the corresponding conduction time of the plurality of drive signals by rounding the corresponding conduction time of the plurality of drive signals to a multiple of the minimum step size.

31. A method for controlling an electrical force delivered to a light source, the light source having a plurality of emitter circuits, each of the plurality of emitter circuits being configured to emit light at a corresponding color temperature, the method comprising: Multiple drive circuits are controlled to control the corresponding intensity levels of the multiple transmitter circuits; The plurality of driving circuits are controlled to control the current intensity level and current color temperature of the accumulated light emitted by the light source toward the target intensity level and target color temperature, respectively. as well as When the target intensity level is less than the threshold intensity level, the target color temperature is limited according to at least one limiting curve, the at least one limiting curve causing the target color temperature to converge toward at least one of a first color temperature or a second color temperature as the target intensity level decreases toward a lower intensity level.

32. The method of claim 31, further comprising: The color temperature is received as a command to control the accumulated light emitted by the light source.

33. The method of claim 32, wherein limiting the target color temperature further comprises: When the color temperature of the command is greater than the threshold color temperature, the target color temperature is limited according to the first limiting curve. The first limiting curve causes the target color temperature to converge toward the first color temperature as the target intensity level decreases toward the low-end intensity level. as well as When the color temperature of the command is less than the threshold color temperature, the target color temperature is limited according to the second limiting curve, which causes the target color temperature to converge toward the second color temperature as the target intensity level decreases toward the low-end intensity level.

34. The method of claim 33, wherein limiting the target color temperature according to the first limiting curve further comprises: When the color temperature of the command exceeds the first limiting curve, the target color temperature is set to be equal to the value of the first limited color temperature on the first limiting curve at the target intensity level; and The limitation of the target color temperature according to the second limitation curve further includes: when the color temperature of the command exceeds the second limitation curve, setting the target color temperature to a value equal to the second limited color temperature on the second limitation curve at the target intensity level.

35. The method of claim 34, further comprising: When the color temperature of the command is greater than the threshold color temperature and the color temperature of the command does not exceed the first limiting curve, the target color temperature is set to be equal to the color temperature of the command. as well as When the color temperature of the command is less than the threshold color temperature and the color temperature of the command does not exceed the second limit curve, the target color temperature is set to be equal to the color temperature of the command.

36. The method of claim 34, further comprising: When the color temperature of the command is greater than the threshold color temperature and the color temperature of the command is less than the first limiting curve at the target intensity level, it is determined that the color temperature of the command exceeds the first limiting curve; and When the color temperature of the command is less than the threshold color temperature and the color temperature of the command is less than the second limit curve at the target intensity level, it is determined that the color temperature of the command exceeds the second limit curve.

37. The load control device of claim 32, wherein limiting the target color temperature further comprises: When the color temperature of the command is greater than the first threshold color temperature, the target color temperature is limited according to the first limiting curve. The first limiting curve causes the target color temperature to converge toward the first color temperature as the target intensity level decreases toward the low-end intensity level. When the color temperature of the command is less than the second threshold color temperature, the target color temperature is limited according to the second limiting curve, which causes the target color temperature to converge toward the second color temperature as the target intensity level decreases toward the low-end intensity level; as well as When the color temperature of the command is between the first threshold color temperature and the second threshold color temperature, the target color temperature is limited according to the third limiting curve and the fourth limiting curve, which cause the target color temperature to converge toward the third color temperature as the target intensity level decreases toward the lower intensity level, wherein the third color temperature is between the first color temperature and the second color temperature.

38. The method of claim 37, further comprising: When the target intensity level is equal to or less than the threshold intensity level and greater than the low-end intensity level, the target color temperature converges towards the first color temperature, the second color temperature and the third color temperature.

39. The method of claim 32, further comprising: Receive a message including the color temperature of the command.

40. The method of claim 31, further comprising: Generate a first drive signal and a second drive signal to control the first drive circuit and the second drive circuit, respectively. The corresponding on-time of the first driving signal and the second driving signal is determined in response to the target intensity level and the target color temperature; as well as The control circuit can adjust the corresponding conduction times of the first drive signal and the second drive signal with the minimum step size by rounding the corresponding conduction times of the first drive signal and the second drive signal to a multiple of the minimum step size.

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