LOAD CONTROL DEVICE FOR CONTROLLING A CONTROLLER FOR A LIGHTING LOAD.

Abstract

If a power interruption occurs while the load is operating at a low end, the load may fail to restart when power is restored. This unwanted operation can be prevented by detecting the application of power to the load and automatically increasing the magnitude of a control signal applied to the load by a sufficient amount for a short period after power is restored. This allows the load to restart at a low end instead of malfunctioning in an electronically shut-down condition.

Description

LOAD CONTROL DEVICE FOR CONTROLLING A CONTROLLER FOR A LIGHTING LOAD BACKGROUND OF THE INVENTION A light source, such as a light-emitting diode (LED) light source, is typically controlled by a load-regulating device (e.g., an LED driver) to provide illumination. A common control method for dimming an LED light source controlled by an LED driver is zero-to-ten-volt (0-10V) control, sometimes referred to as 1-10V control. A 0-10V LED driver is powered by an AC power source, with an external mechanical switch typically coupled between the AC power source and the 0-10V driver to provide a switched hot voltage to the driver. Alternatively, the switched hot voltage can be generated by an external power device (e.g., a power pack). The 0-10V driver controls the intensity of the connected LED light source in response to a 0-10V control signal received from a 0-10V control device (e.g., a 0-10V driver).Typically, the 0-10V device is mounted in an electrical mounting box and includes a dimming actuator (e.g., a slider). The 0-10V control device regulates the DC voltage level of the 0-10V control signal supplied to the controller from a substantially low voltage (e.g., zero to one volt) to a maximum voltage (e.g., approximately ten volts) in response to an actuation of the dimming actuator. For example, the 0-10V controller can control the intensity of the LED light source to a low-end intensity Lle (e.g., approximately 0).1%-10%) when the DC voltage level of the 0-10V control signal is at a substantially low voltage (e.g., zero to one volt) and at a high extreme current Lhe (e.g., approximately 100%) when the DC voltage level of the 0-10V control signal is at the maximum voltage (e.g., approximately ten volts). To turn off the LED light source controlled by the 0-10V controller, power is drawn from the 0-10V controller, for example, by switching the hot voltage to zero volts. The 0-10V control device may include a switching circuit to generate the hot voltage. The switching circuit may include, for example, a mechanical air gap switch, a relay, and / or a bidirectional semiconductor switch, such as a bidirectional triode thyristor (triac), one or more silicon-controlled rectifiers (SCRs), a field-effect transistor (FET) in a rectifier bridge, two FETs in an anti-series connection, one or more insulated-gate bipolar transistors (IGBTs), or any other suitable semiconductor switching circuit. In some cases, the 0-10V control device may be powered through the 0-10V control wires, for example, by drawing current from the 0-10V controller.Prior art 0-10V controllers typically draw between 1-2 milliamps of current, which can be used by the 0-10V control device to power itself. Some 0-10V controllers can respond to occupancy sensors, vacancy sensors, and / or daylight sensors. If the switched hot voltage is controlled to zero volts to turn off the LED light source (for example, by opening the switching circuit of the 0-10V control device or the Rzaenn / zznz / E / YiAi power pack), the 0-10V controller will then be de-energized and will not be able to respond to occupancy sensors, vacancy sensors and / or daylight sensors. Instead of removing power from a 0-10V controller to turn off the LED light source, the 0-10V controller can be controlled to an electronically off state (e.g., standby) in which the 0-10V controller remains energized but turns off the LED light source. The 0-10V controller can be configured to switch between an on state and an electronically off state in response to the 0-10V signal (e.g., using hysteresis). For example, during the on state, the 0-10V control device can be configured to adjust the DC voltage level of the 0-10V control signal between a minimum level (e.g., approximately 0.61–1.00 volts) and a maximum level (e.g., approximately 10 volts) to adjust the intensity of the LED light source between the low-end intensity Lle and the high-end intensity Lhe, respectively.To control the 0-10V controller in the electronic off state, the 0-10V control device can be configured to adjust the DC voltage level of the 0-10V control signal to a standby level. For example, the 0-10V controller can be configured to switch to the electronic off state when the DC voltage level of the 0-10V control signal falls below a drop threshold (e.g., approximately 0.6V). The 0-10V controller can be configured to return to the on state (e.g., to turn on) when the DC voltage level of the 0-10V control signal rises above a rise threshold (e.g., approximately 1.0V), after which the 0-10V controller can adjust the intensity of the LED light source between the low-end intensity Lle and the high-end intensity Lhe as the 0-10V control signal varies between the minimum and maximum levels. Because the drop threshold can be approximately 0.6V, the DC voltage level of the 0-10V control signal can be as low as 0.61V when the 0-10V controller is being controlled at the low-end current Lle. This means that the DC voltage level of the 0-10V control signal at the low-end current Lle can be between the rise threshold and the drop threshold. If there is a momentary power interruption, such as a power outage or manual power cut to the 0-10V controller when the controller is in the ON state, and the DC voltage level of the 0-10V control signal is between the rise threshold and the drop threshold, the 0-10V controller may not turn back on when power is restored (e.g., reapplied) because the DC voltage level of the 0-10V control signal will not be above the rise threshold.It is undesirable for a lighting load that is switched on to not return after a momentary power interruption. BRIEF DESCRIPTION OF THE INVENTION As described herein, a load control device for controlling the amount of power supplied to a lighting load may comprise a communication circuit configured to generate a control signal to regulate the amount of power supplied to the lighting load. The control signal may cause the lighting load to be switched on when the magnitude of the control signal rises above a threshold. The load control device may also comprise a control circuit configured to control the circuit of Rzarnn / zznz / E / YiAi communication for adjusting the magnitude of the control signal in order to adjust the intensity of the lighting load between a low-end intensity and a high-end intensity. The magnitude of the control signal can be less than the threshold when the intensity of the lighting load is being controlled to the low-end intensity. When power has been applied to the lighting load, the control circuit can be configured to determine that a desired magnitude of the control signal is below the threshold, and increase the magnitude of the control signal to be equal to or greater than the threshold before decreasing the magnitude of the control signal to the desired magnitude. The load control device described herein may include a dimming actuator and a potentiometer circuit that responds to the dimming actuator to determine the desired magnitude of the control signal. The load control device may also include a sensing circuit configured to provide an indication of when power has been applied to the lighting load. Once power has been applied to the lighting load and the magnitude of the control signal is set equal to or greater than the threshold, the load control device's control circuit may cause the magnitude of the control signal to be reduced to the desired magnitude for an initial period of time.The control circuit can maintain the magnitude of the control signal constant at a level equal to or greater than the threshold for a second period of time before decreasing the magnitude of the control signal to the desired magnitude for the first period of time. Other features and advantages of the present invention will become apparent from the following description of the invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a simplified block diagram of an exemplary 0-10V load control device. Figure 2 is a simplified flowchart of a voltage detection procedure that can be executed by a microprocessor in a load control device control circuit of Figure 1. Figure 3 is a simplified diagram of exemplary waveforms that illustrate the operation of the load control device during the voltage sensing procedure of Figure 2. Figure 4 is a simplified block diagram of another exemplary 0-10V load control device. Figure 5 is a simplified diagram of exemplary waveforms illustrating the operation of a load control device increment circuit of Figure 4. DETAILED DESCRIPTION OF THE INVENTION Examples are described here of a load control system for controlling the amount of power supplied to an electrical load, such as a lighting load, and more particularly, of a wall-mounted load control device for controlling a load regulating device, such as an LED driver for an LED light source, via a control signal, such as a 0-10V control signal. Figure 1 is a simplified block diagram of a 0-10V load control device Rzaenn / zznz / E / YiAi example 100. The load control device 100 may comprise a hot terminal H adapted to couple to an AC power source 102 and a switched hot terminal SH adapted to couple to an electrical load. The electrical load may comprise a load regulation circuit for controlling a lighting load, such as an LED driver 104 for controlling an LED light source 106. In one example, the load control device 100 may comprise a neutral terminal N adapted to couple to the neutral side of the AC power source 102. In another example, the load control device 100 may not require a connection to the neutral side of the AC power source 102 via the neutral terminal N (e.g., the load control device may be a two-wire load control device).The load control device 100 may comprise first and second control terminals C1, C2 adapted to be coupled to the LED driver 104 via control wiring 108. The LED driver 104 may be configured to control the power supplied to the LED light source 106, and therefore the intensity of the LED light source 106, in response to a direct current (DC) control signal Ves received from the load control device 100 via control wiring 108. For example, the LED driver 104 may be configured to switch the LED light source 106 on and off, and / or adjust the intensity of the LED light source 106 between a low-end intensity (e.g., minimum) Lle and a high-end intensity (e.g., maximum) Lhe in response to the control signal Ves.The LED driver 104 can be configured to control the power supplied to the LED light source 106, for example, by regulating the voltage generated across the LED light source 106 and / or by regulating the current conducted through the LED light source 106. Examples of an LED driver are described in greater detail in Commonly Granted U.S. Patent No. 8,492,987, issued July 23, 2013, entitled LOAD CONTROL DEVICE FOR A LIGHT-EMMITTING DIODE LIGHT SOURCE, and U.S. Patent No. 9,232,574, issued January 5, 2016, entitled FORWARD CONVERTER HAVING A PRIMARY-SIDE CURRENT SENSING CIRCUIT, disclosures of which are incorporated herein by reference. Although described as an LED light source controlled by an LED controller, the electrical load referenced here may comprise an electronic ballast for controlling a fluorescent lamp. The load control device 100 may comprise a switching circuit 110, which may be electrically coupled in series between the hot terminal H and the switched hot terminal SH. The switching circuit 110 may become conductive and non-conductive in response to actuations of an on / off actuator 112 (e.g., a changeover switch) to generate a switched hot voltage Vsh at the switched hot terminal SH. The on / off actuator 112 may comprise a mechanical switch that is actuated by a slider, e.g., when the slider reaches a minimum position (e.g., a slide-to-off slider). The load control device 100 may also include a controller communication circuit 114, which may comprise a current-dissipating circuit adapted to dissipate the current from the LED driver 104 through the control wiring 108. The LED driver 104 may Rzaenn / zznz / E / YiAi be configured to generate a link supply voltage (e.g., approximately 10V) to enable the current-sink circuit of the controller communication circuit 114 to generate the control signal Ves in the control wiring 108. The load control device 100 may comprise a power supply 116 coupled between the hot terminal H and the neutral terminal N to generate a DC supply voltage Veo to energize the low-voltage circuit of the load control device 100. The load control device 100 may comprise a control circuit 120 (e.g., a digital control circuit) configured to control the controller communication circuit 114 to generate the control signal Ves for adjusting the intensity of the LED light source 106. The control circuit 120 may include a microprocessor 122. The control circuit 120 could also include any convenient controller or processing device, such as, for example, a programmable logic device (PLD), a microcontroller, an application-specific integrated circuit (ASIO), or a field-programmable gate array (FPGA). The microprocessor 122 may be configured to determine a desired light intensity Loes for the LED light source 106 and a corresponding desired magnitude Vdes for the control signal Ves in response to an intensity-adjusting actuator 124 (e.g., a slider).For example, the microprocessor 122 can be configured to receive a DC potentiometer brush voltage Vpot from a potentiometer circuit 126, which can respond to the intensity adjustment actuator 124. The microprocessor 122 can be configured to control the magnitude of the control signal Ves to the desired magnitude Vdes to adjust the intensity of the LED light source 106 to the desired light intensity Loes (for example, between a low-end intensity Lle and a high-end intensity Lhe). The microprocessor 122 of the control circuit 120 can generate a direct current (DC) output signal Vcd and can provide the output signal Vcd to the controller communication circuit 114. For example, the microprocessor 122 may include a digital-to-analog converter (DAC) to generate the DC output signal Vcd, which is received by the controller communication circuit 114 to generate the control signal Ves. The microprocessor 122 can adjust the magnitude of the control signal Ves by adjusting the magnitude of the output signal Vcd. The output signal Vcd may be a pulse-width modulated (PWM) signal or a variable-frequency waveform, in response to which the controller communication circuit 114 can be configured to adjust the magnitude of the control signal Ves.The controller communication circuit 114 may comprise a current source circuit or a current source / sink circuit to generate the control signal Ves in response to the output signal Vcd. The LED driver 104 can be controlled to an electronically off (e.g., standby) state, during which the LED driver 104 can turn off the LED light source while the LED driver control circuit remains energized. The LED driver 104 can be configured to switch between an on state and an electronically off state in response to the Ves control signal (e.g., using hysteresis). For example, during the on state, the control circuit 120 can be configured to adjust the DC voltage level of the Ves control signal between a low-end magnitude Vle (e.g., approximately 0.9 volts) and a higher magnitude Rzaenn / zznz / E / YiAi high-end Vhe (e.g., ten volts) to adjust the intensity of the LED light source 106 between the low-end intensity Lle and the high-end intensity Lhe, respectively. To control the LED driver 104 to the electronic off state, the control circuit 120 can be configured to adjust the DC voltage level of the control signal Ves to a standby level. For example, the LED driver 104 can be configured to switch to the electronic off state when the DC voltage level of the 0-10V control signal falls below a drop threshold Vth-drop (e.g., approximately 0.6V). The LED driver 104 can be configured to return to the on state (e.g., to turn on) when the DC voltage level of the control signal Ves rises above a rise threshold Vth-rise (e.g., approximately 1).0V), after which the LED driver 104 can adjust the intensity of the LED light source 106 between the low-end intensity Lle and the high-end intensity Lhe as the control signal Ves varies between the low-end magnitude VLE and the high-end magnitude Vhe. During the on state, the low-end magnitude VLE of the Ves control signal may be less than the rise threshold Vth-rise. For example, the low-end magnitude VLE of the Ves control signal may be approximately 0.9V, while the rise threshold Vth-rise may be approximately 1.0V. If the LED driver 104 and the load control device 100 temporarily lose power while the load control device is controlling the intensity of the LED light source 106 to the low-end intensity Lle, the magnitude of the Ves control signal (e.g., the low-end magnitude Vle) may not exceed the rise threshold Vth-rise when power is restored, and the LED driver 104 will be unable to turn on the LED light source 106.Similarly, when the on / off actuator 112 is actuated to close the switching circuit 110 to turn on the LED light source 106 and the intensity adjustment actuator 122 is set to the low-end intensity Lle, the magnitude of the control signal Ves may also not exceed the rise threshold Vth-rise and the LED driver 104 may not turn on the LED light source 106 when the LED driver 104 is turned on by the switching circuit 110. Therefore, control circuit 120 can be configured to at least temporarily increase the magnitude of the control signal Vcd when power is applied (e.g., initially applied or reapplied) to the lighting load 106 (i.e., the LED driver 104). For example, control circuit 120 can be configured to temporarily increase the magnitude of the control signal Ves to equal or above the rise threshold Vth-rise when power is applied to the LED driver after an interruption and the desired magnitude Vdes for the control signal Vos is initially less than the rise threshold Vth-rise. The power interruption could be caused by a power outage or manual switching off of the on / off actuator 112, for example.The control circuit 120 may comprise a voltage sensing circuit 128 configured to generate a voltage sensing signal Vdetection that can indicate when power has been applied to the LED driver 104. For example, the voltage sensing circuit 128 may be coupled between the switched hot terminal SH and the neutral terminal N to receive the switched hot voltage Vsh as shown in Figure 1. The voltage sensing circuit 128 may be configured to drive the voltage sensing signal Vdetection to a high level towards the voltage. Rzaenn / zznz / E / YiAi supply I see when the magnitude of the switched hot voltage Vsh rises above a voltage detection threshold Vth-detection (for example, the voltage detection circuit 128 may comprise a comparator circuit). In one example, the control circuit 120 may be configured to determine that power has just been applied to the LED driver 104 in response to detecting a rising edge of the voltage detection signal Vdetection.In another example, the voltage detection signal Vdetection can simply be a scaled version of the switched hot voltage Vsh (for example, the voltage detection circuit 128 can comprise a scaling circuit, such as a resistive divider), and the control circuit 120 can be configured to sample the voltage detection signal Vdetection and compare the sampled magnitude with the voltage detection threshold Vth-detection to determine when power has been applied (or re-applied) to the LED driver 104. Although the switching circuit 110 and the on / off actuator 112 are shown in Figure 1 as integral parts of the load control device 100, the switching circuit and / or the on / off actuator 112 could be external to the load control device 100 (for example, the switching circuit could be included in an external light switch or an external switching power pack). Furthermore, the communication circuit 110 could comprise a relay controlled by the microprocessor 122, and the on / off actuator 112 could comprise a low-voltage switch (for example, a mechanical touch switch) to generate a low-voltage signal that is received by the microprocessor 122.The microprocessor 122 can be configured to detect that the low-voltage switch has been activated, close the relay, and temporarily increase the magnitude of the Ves control signal (e.g., if the voltage detection circuit 128 needs it). As described herein, the power that is applied (e.g., initially applied or reapplied) to the lighting load 106 can occur when power is restored after a temporary power interruption (e.g., by an electric utility company), when the switching circuit 110 is closed, and / or when an external switching circuit (e.g., in a light switch or switching power pack) coupled in signal between the AC power source 102 and the lighting load 106 is closed. A person skilled in the art will recognize that there are other ways in which power can be applied to a lighting load. Figure 2 is a simplified flowchart of a voltage sensing procedure 200 that can be executed by the microprocessor 122 of the control circuit 120 of the load control device 100. Figure 3 is a simplified diagram of exemplary waveforms illustrating the operation of the load control device 100 during the voltage sensing procedure 200. The voltage sensing procedure 200 can begin when the microprocessor 122 detects a rising edge of the voltage sensing signal Vdetection in step 210, indicating that power has been newly applied to the LED driver 104 (e.g., as shown at time tsuBiDA in Figure 3), for example, after an interrupt.The microprocessor 122 can then determine the desired magnitude Vdes for the control signal Ves (for example, using the desired light intensity Ldes determined from the intensity adjustment actuator 122) in step 212. If the desired magnitude Vdes is not less than the rise threshold Vth-rise in step 214, the... The microprocessor 122 can set the magnitude of the control signal Ves to the desired magnitude Vdes in step 216, before exiting the voltage sensing procedure 200. If the desired magnitude Vdes is less than the rise threshold Vth-rise in step 214, the microprocessor 122 can set the magnitude of the control signal Ves to be equal to the rise threshold Vth-rise plus a phase shift voltage Vphase in step 218. For example, the phase shift voltage Vphase can be sized to ensure that the magnitude of the control signal Ves is greater than the rise threshold Vth-rise when power is applied to the LED driver 104 (for example, as shown at time tsuBiDA in Figure 3) to control the LED driver 104 to the ON state.The microprocessor 122 can then fade (i.e., adjust) the magnitude of the control signal Ves to the desired magnitude Vdes (i.e., the low-end magnitude Vle as shown in Figure 3) during a first time period Tfade, which can be approximately 0.51 seconds, in step 220, before exiting the voltage sensing procedure 200. Although not shown in Figure 2, the microprocessor 122 can hold the magnitude of the control signal Ves equal to the rise threshold Vth-rise plus the phase-off voltage Vphase for a second time period before beginning to fade the magnitude of the control signal Ves to the desired magnitude Vdes during the time period Tfade. The operation of control circuit 120 in response to the application of power to the LED driver 104 can be controllable and / or programmable. For example, control circuit 120 can be configured to adjust the magnitude of the phase shift voltage Vphase, and / or the length of the first and / or second time period (e.g., the fade time period Tfade), in response to an external input (e.g., a programming input). The external input can be received, for example, from an actuation of the dimming actuator 124 and / or the on / off actuator 112, an actuation of one or more programming buttons (not shown), an actuation of one or more separate programming potentiometers (not shown), and / or one or more messages received through a communication circuit (not shown). Figure 4 is a simplified block diagram of another example of a 0-10V load control device 300. The load control device 300 can be configured to control the amount of power supplied to an electrical load. The electrical load may include, for example, a load regulation circuit for controlling the electrical load, such as an LED driver 304 for controlling an LED light source 306. The load control device 300 may or may not be electrically coupled in series between an AC power source 302 and the electrical load. The load control device 300 may comprise first and second control terminals C1, C2 adapted to be coupled to the LED driver 304 by means of control wiring 308. The load control device 300 may comprise a communication circuit configured to generate a control signal to regulate the power supplied to the LED lighting load 306.The load control device 300 may include, for example, a current-sink circuit 310 electrically coupled to the control terminals C1, C2 to dissipate the current from the LED driver 104 through the control wiring 108. The current-sink circuit 310 may be configured to generate a control signal CD Ves to control the LED driver 304 to turn the LED light source 306 on and off. Rzaenn / zznz / E / YiAi adjust the intensity of the LED light source 306 when the LED light source 306 is on. The load control device 300 may comprise a control circuit 320 (e.g., an analog control circuit) configured to control the current-dissipating circuit 310 to generate the control signal Ves to switch the LED light source 306 on and off, and to adjust the intensity of the LED light source 306. The control circuit 320 may comprise a potentiometer circuit 322 to generate a DC output signal Vcd in response to an intensity-adjusting actuator 324 (such as, for example, a slider, selector wheel, or knob). The potentiometer circuit 322 may provide the DC output signal Vcd to the current-dissipating circuit 310 to control the magnitude of the control signal Ves to a desired magnitude Vdes to adjust the intensity of the LED light source 306 to a desired light intensity Ldes (e.g., between a low-end intensity Lle and a high-end intensity Lhe). The LED driver 304 can be controlled to an electronic off (e.g., standby) state, during which the LED driver 304 can turn off the LED light source while the LED driver control circuit remains energized (e.g., in a manner similar to the LED driver 104 shown in Figure 1). The LED driver 304 can be configured to switch between an on state and the electronic off state in response to the Ves control signal (e.g., using hysteresis). For example, the LED driver 304 can be configured to switch to the on state (i.e., to turn on) when the DC voltage level of the Ves control signal rises above a rise threshold Vth-rise (e.g., approximately 1.0V). As with the load control device 100 in Figure 1, the low-end magnitude Vle of the control signal Ves generated by the load control device 300 may be less than the rise threshold Vth-rise. In some cases (such as, for example, when a desired magnitude of the control signal Ves is less than the rise threshold Vth-rise when power is applied to the LED light source 306), the control circuit 320 may be configured to temporarily increase the magnitude of the control signal Ves to be equal to or greater than the rise threshold Vth-rise before decreasing the magnitude of the control signal Ves to the desired magnitude. The control circuit 320 may be configured to determine when power is applied to the LED light source 306 (for example, to the driver 304) in response to the magnitude (for example, a change in magnitude) of the control signal Ves generated by the current-dissipating circuit 310.For example, LED driver 304 can be configured to generate a link supply voltage to allow current-sink circuit 310 to generate the control signal Ves in control wiring 308. Because of this, the magnitude of the control signal Vos can indicate when LED driver 304 is energized. For example, when LED driver 304 is not energized, the magnitude of the control signal Vos may drop to approximately 0 volts. When power is restored, the magnitude of the control signal Ves may return to the level prior to the power loss. Control circuit 320 can be configured to determine that power has been lost and reapplied based on changes (e.g., drops and rises) in the magnitude of the control signal Ves. The control circuit 320 may comprise an increment circuit 330 for incrementing Rzaenn / zznz / E / YiAi temporarily increases the magnitude of the control signal Ves (e.g., when power is applied to the LED driver 304). Figure 5 is a simplified diagram of exemplary waveforms illustrating the operation of the increment circuit 330 of the load control device 300. The increment circuit 330 may comprise a bipolar junction transistor Q332, which in turn may include a collector coupled to an anode of a capacitor C334, the series combination of which is coupled between the first control terminal C1 and the brush of the potentiometer circuit 322 (e.g., the DC output signal Vcd of the control circuit 320), with an emitter of transistor Q332 coupled to the first control terminal C1, and a cathode of capacitor C334 coupled to the brush of the potentiometer circuit 322 and the current-sink circuit 310.The 330 increment circuit may also include two resistors R336, R338 connected in series between the first and second control terminals C1, C2. The junction point of resistors R336, R338 may be connected to the base of transistor Q332. When the magnitude of the control signal Vs is approximately zero volts (for example, when the LED driver 304 is not powered), transistor Q332 may not be conducting and capacitor C334 may not be charged. After power is applied to the LED driver 304, it may begin to generate the link supply voltage (for example, through resistors R334 and R336 of the 330 boost circuit). Once the voltage across resistor R334 exceeds the rated base-emitter voltage of transistor Q332, the transistor may become conductive. When transistor Q332 first becomes conductive, capacitor C334 may not be charged, and therefore transistor Q332 may bring the magnitude of the DC output signal Vcd toward the magnitude at the first control terminal C1.This can cause the current-dissipating circuit 310 to temporarily increase the magnitude of the control signal Ves to be greater than the rise threshold Vth-rise (for example, by a phase shift voltage Vphase). As capacitor C334 charges, the magnitude of the DC output signal Vcd may continue to fall until capacitor C334 is fully charged and the magnitude of the DC output signal Vcd has returned to the level determined by the potentiometer circuit 322 and the intensity adjustment actuator 324 (for example, the low-end magnitude Vle as shown in Figure 5). The increment circuit 330 can be configured to temporarily increase the magnitude of the control signal Ves by an increment period Tincrement (for example, as shown in Figure 5).

Claims

1. A load control device for controlling the intensity of a lighting load, the load control device comprising: a communication circuit configured to generate a control signal for controlling the intensity of the lighting load, the control signal having the capability to cause the lighting load to be switched on when a magnitude of the control signal increases above a threshold; and a control circuit configured to control the communication circuit to adjust the magnitude of the control signal in order to adjust the intensity of the lighting load between a low-end intensity and a high-end intensity, the control signal having a magnitude less than the threshold when the intensity of the lighting load is being controlled to the low-end intensity;wherein, when power has been applied to the lighting load, the control circuit is configured to temporarily set the magnitude of the control signal to be greater than a desired magnitude of the control signal before decreasing the magnitude of the control signal to the desired magnitude.

2. The load control device according to claim 1, further comprising: an intensity adjustment actuator; wherein the control circuit comprises a potentiometer circuit that responds to the intensity adjustment actuator to determine the desired magnitude of the control signal.

3. The load control device according to claim 2, wherein the control circuit comprises a digital control circuit configured to determine that the desired magnitude of the control signal is below the threshold when power has been applied to the lighting load, controlling the communication circuit to set the magnitude of the control signal to be equal to or greater than the threshold if the desired magnitude of the control signal is below the threshold, and decreasing the magnitude of the control signal to the desired magnitude during a first period of time.

4. The load control device according to claim 3, wherein the control circuit is configured to set the magnitude of the control signal to be equal to the threshold plus a phase-off amount if the desired magnitude of the control signal is less than the threshold when power has been applied to the lighting load.

5. The load control device according to claim 3, wherein the control circuit is configured to maintain the magnitude of the control signal constant at a level equal to or greater than the threshold for a second time period when power has been applied to the lighting load before decreasing the magnitude of the control signal to the desired magnitude during the first time period.

6. The load control device according to claim 3, further comprising: a detection circuit configured to provide an indication of when power has been applied to the lighting load.

7. The load control device according to claim 3, wherein the control circuit is configured to control the communication circuit to set the magnitude of the control signal to equal the desired magnitude if the desired magnitude of the control signal is greater than or equal to the threshold.

8. The load control device according to claim 3, wherein the digital control circuit comprises at least one microprocessor, one microcontroller, one programmable logic device, one application-specific integrated circuit, or one field-programmable gate array.

9. The load control device according to claim 2, wherein the control circuit comprises an analog control circuit including an increment circuit coupled to a potentiometer circuit tap to increase the magnitude of the control signal.

10. The load control device according to claim 9, wherein the increment circuit is configured to set the magnitude of the control signal to be equal to the desired magnitude plus a phase shift amount when power has been applied to the lighting load, and subsequently decrease the magnitude of the control signal to the desired magnitude.

11. The load control device according to claim 10, wherein the increment circuit is configured to maintain the magnitude of the control signal greater than or equal to the threshold for a period of time after power has been applied to the lighting load.

12. The load control device according to claim 1, further comprising: a switching circuit adapted to be electrically coupled in series between an AC power source and a load regulating device for the lighting load, the load regulating device being configured to receive the control signal generated by the communication circuit; wherein the control circuit is configured to control the switching circuit to cause power to be applied to the lighting load.

13. The load control device according to claim 1, wherein the communication circuit comprises a current dissipating circuit.

14. A method for controlling the intensity of a lighting load, the method comprising: generating a control signal to control the intensity of the lighting load, the control signal having the capability to cause the lighting load to be switched on when a magnitude of the control signal increases above a threshold; adjusting, after the lighting load has been switched on, the magnitude of the control signal to control the intensity of the lighting load between a low-end intensity and a high-end intensity, the magnitude of the control signal being equal to or less than the threshold when the intensity of the lighting load is being controlled to the low-end intensity; when power has been applied to the lighting load, temporarily adjusting the magnitude of the control signal to be greater than a desired magnitude of the control signal;and subsequently decrease the magnitude of the control signal to the desired magnitude.

15. The method according to claim 14, further comprising: before temporarily adjusting the magnitude of the control signal to be greater than the desired magnitude of the control signal, determining that the desired magnitude of the control signal is below the threshold when power has been applied to the lighting load.

16. The method according to claim 15, wherein temporarily adjusting the magnitude of the control signal to be greater than the desired magnitude of the control signal further comprises: adjusting the magnitude of the control signal to be equal to or greater than the threshold if the desired magnitude of the control signal is below the threshold; and decreasing the magnitude of the control signal to the desired magnitude during a first period of time.

17. The method according to claim 16, wherein adjusting the magnitude of the control signal to be equal to or greater than the threshold further comprises adjusting the magnitude of the control signal to be equal to the threshold plus a phase shift amount if the desired magnitude of the control signal is less than the threshold when power has been applied to the lighting load.

18. The method according to claim 16, wherein temporarily adjusting the magnitude of the control signal to be greater than a desired magnitude of the control signal further comprises maintaining the magnitude of the control signal at a level equal to or greater than the threshold for a second time period before being reduced to the desired magnitude for the first time period.

19. The method according to claim 16, further comprising: detecting, through a detection circuit, that energy has been applied to the lighting load.

20. The method according to claim 16, further comprising: adjusting the magnitude of the control signal to be equal to the desired magnitude if the desired magnitude of the control signal is greater than or equal to the threshold.

21. The method according to claim 14, wherein temporarily adjusting the magnitude of the control signal to be greater than a desired magnitude of the control signal further comprises: adjusting the magnitude of the control signal to be equal to the desired magnitude plus a phase shift amount when power has been applied to the lighting load; and subsequently decreasing the magnitude of the control signal to the desired magnitude.

22. The method according to claim 21, wherein temporarily adjusting the magnitude of the control signal to be greater than a desired magnitude of the control signal further comprises maintaining the magnitude of the control signal greater than or equal to the threshold for a period of time after power has been applied to the lighting load.

23. A load control device for controlling a light-emitting diode (LED) driver for an LED light source, the load control device comprising: a communication circuit adapted to be coupled to the LED driver via control wiring, the communication circuit is configured to generate a control signal in the control wiring to control an intensity of the LED light source, the LED driver is configured to turn on the LED light source when a magnitude of the control signal increases above a threshold;and a control circuit configured to control the communication circuit to adjust the magnitude of the control signal in order to adjust the intensity of the LED light source between a low-end intensity and a high-end intensity, the control signal having a magnitude less than the threshold when the intensity of the LED light source is being controlled to the low-end intensity; wherein, when power has been applied to the LED driver, the control circuit is configured to temporarily set the magnitude of the control signal to be greater than a desired magnitude of the control signal before decreasing the magnitude of the control signal to the desired magnitude.

24. The load control device according to claim 23, further comprising: an intensity adjustment actuator; wherein the control circuit comprises a potentiometer circuit that responds to the intensity adjustment actuator to determine the desired magnitude of the control signal.

25. The load control device according to claim 24, wherein the control circuit comprises a digital control circuit configured to determine that the desired magnitude of the load signal is below the threshold when power has been applied to the LED driver, controlling the communication circuit to set the magnitude of the control signal to be equal to or greater than the threshold if the desired magnitude of the control signal is below the threshold, and decreasing the magnitude of the control signal to the desired magnitude during a first period of time.

26. The load control device according to claim 25, wherein the control circuit is configured to set the magnitude of the control signal to be equal to the threshold plus a phase amount if the desired magnitude of the control signal is less than the threshold when power has been applied to the LED driver.

27. The load control device according to claim 25, wherein the control circuit is configured to maintain the magnitude of the control signal constant at a level equal to or greater than the threshold for a second time period when power has been applied to the LED driver before decreasing the magnitude of the control signal to the desired magnitude during the first time period.

28. The load control device according to claim 25, further comprising: a detection circuit configured to provide an indication of when power has been applied to the LED driver. Rzaenn / zznz / E / YiAi 29. The load control device according to claim 25, wherein the control circuit is configured to control the communication circuit to set the magnitude of the control signal to equal the desired magnitude if the desired magnitude of the control signal is greater than or equal to the threshold.

30. The load control device according to claim 24, wherein the control circuit comprises an analog control circuit including an increment circuit coupled to a brush of the potentiometer circuit to increase the magnitude of the control signal.

31. The load control device according to claim 30, wherein the increment circuit is configured to set the magnitude of the control signal to be equal to the desired magnitude plus a phase shift amount when power has been applied to the LED driver, and subsequently decrease the magnitude of the control signal to the desired magnitude.

32. The load control device according to claim 31, wherein the increment circuit is configured to maintain the magnitude of the control signal greater than or equal to the threshold for a period of time after power has been applied to the LED driver.

33. The load control device according to claim 23, further comprising: a switching circuit adapted to be electrically coupled in series between an AC power source and an LED driver; wherein the control circuit is configured to control the switching circuit to cause power to be applied to the LED driver.

34. The load control device according to claim 23, wherein the communication circuit comprises a current dissipating circuit.

35. A method for controlling a light-emitting diode (LED) driver for an LED light source, the LED driver being coupled to control wiring to receive a control signal, the method comprising: generating the control signal in the control wiring to control an intensity of the LED light source, the LED driver being configured to turn on the LED light source when a magnitude of the control signal increases above a threshold; adjusting, after the LED light source has been turned on, the magnitude of the control signal to control the intensity of the LED light source between a low-end intensity and a high-end intensity, the magnitude of the control signal being equal to or less than the threshold when the intensity of the LED light source is being controlled to the low-end intensity;When power has been applied to the LED driver, temporarily adjust the magnitude of the control signal to be greater than a desired magnitude of the control signal; and subsequently decrease the magnitude of the control signal to the desired magnitude.

36. The method according to claim 35, further comprising, before temporarily adjusting the magnitude of the control signal to be greater than the desired magnitude of the control signal, determining that the desired magnitude of the control signal is below the threshold when power has been applied to the LED driver. Rzaenn / zznz / E / YiAi 37. The method according to claim 36, wherein temporarily adjusting the magnitude of the control signal to be greater than the desired magnitude of the control signal further comprises: adjusting the magnitude of the control signal to be equal to or greater than the threshold if the desired magnitude of the control signal is below the threshold; and decreasing the magnitude of the control signal to the desired magnitude during a first period of time.

38. The method according to claim 37, wherein adjusting the magnitude of the control signal to be equal to or greater than the threshold further comprises adjusting the magnitude of the control signal to be equal to the threshold plus a phase shift amount if the desired magnitude of the control signal is less than the threshold when power has been applied to the LED driver.

39. The method according to claim 37, wherein temporarily adjusting the magnitude of the control signal to be greater than the desired magnitude of the control signal further comprises maintaining the magnitude of the control signal at a level equal to or greater than the threshold for a second time period before being reduced to the desired magnitude for the first time period.

40. The method according to claim 37, further comprising: detecting, through a detection circuit, that energy has been applied to the LED driver.

41. The method according to claim 37, further comprising: adjusting the magnitude of the control signal to be equal to the desired magnitude if the desired magnitude of the control signal is greater than or equal to the threshold.

42. The method according to claim 35, wherein temporarily adjusting the magnitude of the control signal to be greater than the desired magnitude of the control signal further comprises: adjusting the magnitude of the control signal to be equal to the desired magnitude plus a phase shift when power has been applied to the LED driver; maintaining the magnitude of the control signal greater than or equal to the threshold for a period of time after power has been applied to the LED driver; and subsequently decreasing the magnitude of the control signal to the desired magnitude.

43. A load control device for controlling an electrical load having a load regulating circuit and a lighting load, the load control device comprising: a current dissipating circuit configured to dissipate current from the electrical load to generate a direct current (DC) control signal to cause the load regulating circuit to control an intensity of the lighting load, the DC control signal having the ability to cause the load regulating circuit to turn on the lighting load when the magnitude of the DC control signal increases above a threshold;and a control circuit configured to control current dissipation to adjust the magnitude of the DC control signal to a first magnitude to cause the load regulating circuit to adjust the intensity of the lighting load to a high-end intensity and a second magnitude to cause the load regulating circuit to adjust the intensity of the lighting load to a low-end intensity, wherein the second magnitude of the DC control signal is less than the threshold; wherein, when power has been applied to the electrical load, the control circuit is configured to temporarily set the magnitude of the DC control signal to be greater than a desired magnitude of the DC control signal before decreasing the magnitude of the DC control signal to the desired magnitude.

44. The load control device according to claim 43, further comprising: an intensity adjustment actuator; wherein the control circuit comprises a potentiometer circuit that responds to the intensity adjustment actuator to determine the desired magnitude of the DC control signal.

45. The load control device according to claim 44, wherein the control circuit comprises a digital control circuit configured to: determine that the desired magnitude of the control signal CD is below the threshold when power has been applied to the electrical load; control the current dissipating circuit to set the magnitude of the control signal CD to be equal to or greater than the threshold if the desired magnitude of the control signal CD is below the threshold; and decrease the magnitude of the control signal CD to the desired magnitude during a first period of time.

46. ​​The load control device according to claim 45, wherein the control circuit is configured to set the magnitude of the CD control signal to be equal to the threshold plus a phase amount if the desired magnitude of the CD control signal is less than the threshold when power has been applied to the electrical load.

47. The load control device according to claim 45, wherein the control circuit is configured to maintain the magnitude of the DC control signal constant at a level equal to or greater than the threshold for a second time period when power has been applied to the electrical load before decreasing the magnitude of the DC control signal to the desired magnitude during the first time period.

48. The load control device according to claim 45, further comprising: a detection circuit configured to provide an indication of when power has been applied to the electrical load.

49. The load control device according to claim 45, wherein the control circuit is configured to control the current dissipating circuit to set the magnitude of the control signal CD to equal the desired magnitude if the desired magnitude of the control signal CD is greater than or equal to the threshold.

50. The load control device according to claim 45, wherein the digital control circuit Rzarnn / zznz / E / YiAi comprises at least one microprocessor, one microcontroller, one programmable logic device, one application-specific integrated circuit, or one field-programmable gate array.

51. The load control device according to claim 44, wherein the control circuit comprises an analog control circuit including an increment circuit coupled to a potentiometer circuit tap for increasing the magnitude of the DC control signal.

52. The load control device according to claim 51, wherein the increment circuit is configured to set the magnitude of the DC control signal to be equal to the desired magnitude plus a phase shift amount when power has been applied to the electric load, and subsequently decrease the magnitude of the DC control signal to the desired magnitude.

53. The load control device according to claim 52, wherein the increment circuit is configured to maintain the magnitude of the DC control signal greater than or equal to the threshold for a period of time after power has been applied to the electrical load.

54. The load control device according to claim 53, further comprising: a switching circuit adapted to be electrically coupled in series between an AC power source and the load regulating circuit of the electric load, the load regulating circuit being configured to receive the DC control signal generated by the current dissipating circuit; wherein the control circuit is configured to control the switching circuit to cause power to be applied to the electric load.

55. A method for controlling an electrical load having a load regulating circuit and a lighting load, the method comprising: generating a DC control signal to cause the load regulating circuit to control an intensity of the lighting load by dissipating current from the electrical load, the DC control signal having the ability to cause the load regulating circuit to turn on the lighting load when a magnitude of the DC control signal increases above a threshold; adjusting the magnitude of the DC control signal to a first magnitude to cause the load regulating circuit to adjust the intensity of the lighting load to a high-end intensity and to a second magnitude to cause the load regulating circuit to adjust the intensity of the lighting load to a low-end intensity, wherein the second magnitude of the DC control signal is less than the threshold;When power has been applied to the electrical load, temporarily adjust the magnitude of the control signal to be greater than a desired magnitude of the DC control signal; and subsequently decrease the magnitude of the DC control signal to the desired magnitude.

56. The method according to claim 55, further comprising: before temporarily adjusting the magnitude of the CD control signal to be greater than the desired magnitude of the CD control signal, determining that the desired magnitude of the CD control signal is below the threshold when power has been applied to the electrical load.

57. The method according to claim 56, wherein temporarily adjusting the magnitude of the control signal CD to be greater than the desired magnitude of the control signal CD further comprises: adjusting the magnitude of the control signal CD to be equal to or greater than the threshold if the desired magnitude of the control signal CD is below the threshold; and decreasing the magnitude of the control signal CD to the desired magnitude during a first period of time.

58. The method according to claim 57, wherein adjusting the magnitude of the CD control signal to be equal to or greater than the threshold further comprises adjusting the magnitude of the CD control signal to be equal to the threshold plus a phase shift amount if the desired magnitude of the CD control signal is less than the threshold when power has been applied to the electrical load.

59. The method according to claim 58, wherein temporarily adjusting the magnitude of the CD control signal to be greater than a desired magnitude of the CD control signal further comprises maintaining the magnitude of the CD control signal at a level equal to or greater than the threshold for a second time period before being reduced to the desired magnitude for the first time period.

60. The method according to claim 57, further comprising: adjusting the magnitude of the CD control signal to be equal to the desired magnitude if the desired magnitude of the CD control signal is greater than or equal to the threshold.

61. The method according to claim 55, wherein temporarily adjusting the magnitude of the CD control signal to be greater than a desired magnitude of the CD control signal further comprises: adjusting the magnitude of the CD control signal to be equal to the desired magnitude plus a phase shift when energy has been applied to the electric load; and subsequently decreasing the magnitude of the CD control signal to the desired magnitude.

62. The method according to claim 61, wherein temporarily adjusting the magnitude of the control signal CD to be greater than a desired magnitude of the control signal further comprises maintaining the magnitude of the control signal CD greater than or equal to the threshold for a period of time after power has been applied to the electrical load.

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