JP5690930B2 - Bleed circuit to prevent inappropriate dimming operation and related method - Google Patents

Description

  The present invention generally relates to the control of light sources. More specifically, the various inventive methods and apparatus disclosed herein relate to the prevention of light source flicker due to dimmer misignition.

  Digital lighting technology, ie lighting based on semiconductor light sources such as light emitting diodes (LEDs), provides a viable alternative to conventional fluorescent, HID and incandescent lamps. The functional benefits and benefits of LEDs include high energy conversion efficiency and optical efficiency, durability, low operating costs, and many others. Recent advances in LED technology have provided a wide range of efficient and robust light sources that enable various lighting effects in many applications. Some appliances that implement these light sources also have one or more LEDs that can generate different colors, such as red, green, and blue, but also have independent LED outputs to produce different color and color changing lighting effects. It features a light module that also has a controlling processor. This is discussed in detail, for example, in US Pat. Nos. 6,016,038 and 6,211,626.

  Many lighting devices use dimmers. Conventional dimmers work well with incandescent (bulb and halogen) lamps. However, in other types of electronic light sources such as compact fluorescent lamps (CFL), low voltage halogen lamps using electronic transformers, and solid state lighting (SSL) such as LEDs and OLEDs Problems arise. Conventional dimmers typically chop a portion of each waveform of the input main voltage signal and pass the remaining portion of the waveform to the light source. Leading edge or tripolar alternating current (triac) dimmers are widely used as simple circuit designs and low cost types of dimmers.

  FIG. 1 is a schematic diagram of a standard lighting system 100 that includes a leading edge triac dimmer 104 coupled to a main voltage 102. The leading edge triac dimmer 104 supplies an adjustable voltage signal to the lamp 106 and controls the light output by the lamp 106 to be adjustable. FIG. 2 shows the output waveform of the leading edge triac dimmer 104. Here, the leading edge of each waveform is chopped.

  In the leading edge triac dimmer 104 as shown in FIG. 1, the following parameters are required to enable proper operation. The latch current is the minimum main current required to maintain the triac in the on state immediately after the triac is switched from the off state to the on state and the trigger signal is removed. Holding current is the minimum main current required to keep the triac on. The holding current is always less than the latch current. However, the higher the sensitivity of the device, the closer the holding current value is to the latch current value. Therefore, the main current of the triac is higher than the latch current of the triac immediately after the gate control current is removed in order to maintain the conduction of the triac over the entire range of dimming angles, and more than the holding current of the dimmer triac. Must always be high. Also, a return path is necessary to ensure proper dimming operation. If the input impedance of the light source driver is relatively high, the triac will not fire properly and the ignition timing of the triac will be affected.

A standard problem with leading edge triac dimmers as shown in FIG. 1 is resonance. Resonance between the inductor in the leading edge triac dimmer and the capacitor in the light source driver causes resonance of the input current supplied from the main voltage 102 to the dimmer 104. In FIG. 1, the light source driver is considered to be incorporated in the lamp 106. Such resonance can typically occur, for example, when a leading edge triac dimmer is used to dim an LED light source. As resonance increases, the resulting minimum input current supplied to the dimmer 104 will be lower than the holding current required to keep the TRIAC in a conducting state, causing the TRIAC to switch off or misfire. Resulting in. The false ignition causes repeated spikes (multifire) in the ignition current supplied from the dimmer 104 to the lamp 106 during a half-wave period. This is shown, for example, in FIG. FIG. 3 shows the ignition current C2 of the light source driver and the corresponding input voltage C4 of the light source driver. As a result, the light source driver switches on and off, so that the lamp 106 flashes on and off.
A known approach to solving this resonance / flicker problem is to configure a resistor in series with the driver capacitor for the purpose of dumping the resonant ignition current. However, this approach is not an attractive solution because it increases power consumption.

  Therefore, there is a need in the art to provide a simple and low cost design circuit and associated method that does not have excessive power consumption, preventing light source flicker.

  The present disclosure relates to a novel method and apparatus for controlling a bleed current and supplying the bleed current until resonance of the dimmer input current stops. In general, in one aspect, a bleed circuit is provided, the bleed circuit having a bus configured to provide a voltage signal from a dimmer to adjustably dimm the light output by the light source. The bleed circuit includes a detection circuit configured to detect a potential of the bus and supply a control signal in response to the detected potential. The bleed circuit further includes a bleed component configured to supply a bleed current from the bus to the dimmer via a return current path. A delay circuit is further included. The delay circuit delays the control signal by a predetermined delay, supplies the delayed control signal to the blade component, and responds to the delayed control signal by the bleed component until the resonance of the input current at the dimmer stops. Configured to allow sharing of bleed current.

In another aspect, a system for controlling power delivered to a light source is provided. The system has a dimmer coupled to the main voltage and configured to provide a voltage signal to adjustably dimm the light output by the light source. The system further includes a rectifier circuit configured to supply the rectified voltage signal to the bus in response to the voltage signal. A bleed circuit is also included. The bleed circuit is configured to supply a bleed current to the dimmer via a return current path. A power converter is also included. The power converter is configured to drive the light source in response to the rectified voltage signal. The bleed circuit is further configured to supply a bleed current in response to the control signal until the input current resonance in the dimmer stops.
In yet another aspect, a method for removing flicker from light output by a light emitting diode is provided. The method includes supplying a voltage signal from the dimmer to adjustably adjust light output by the light emitting diode, supplying a control signal in response to a detected potential of the voltage signal, and a bleed current. Supplying to the dimmer, and delaying the control signal by a predetermined delay to provide the delayed control signal. The bleed current is supplied to the dimmer in response to the delayed control signal until the input current resonance in the dimmer stops.

  As used herein for purposes of this disclosure, the term “LED” includes any electroluminescent diode or other type of carrier injection / junction based system that can generate radiation in response to an electrical signal. Should be understood. Thus, the term LED includes, but is not limited to, various semiconductor-based structures that emit light in response to current, light emitting polymers, organic light emitting diodes (OLEDs), electroluminescent strips, and the like. In particular, the term LED can be configured to generate radiation of one or more of various components of the infrared spectrum, ultraviolet spectrum, and visible spectrum (generally including radiation wavelengths of about 400 nanometers to about 700 nanometers). Represents all types of light emitting diodes (including semiconductors and organic light emitting diodes). For example, one implementation of an LED that is configured to produce essentially white (eg, a white LED) has a large number of individually emitting different spectra of electroluminescence that mix together to form essentially white light. You may have a die. In another implementation, the white LED may be associated with a phosphor that converts electroluminescence having a first spectrum into a different second spectrum. In one example of this implementation, electroluminescence having a relatively short wavelength and a narrow bandwidth spectrum "pumps" the phosphor, and in turn emits longer wavelength radiation having a somewhat broad spectrum.

  It should also be understood that the term LED is not limited to physical and / or electrical package type LEDs. For example, as described above, an LED may represent a single light emitting device having multiple dies that individually emit different spectrums of radiation (eg, may or may not be individually controllable). An LED may also be associated with a phosphor that is considered part of an LED (eg, some types of white LEDs).

  The term “light source” is not limiting and includes sources based on LEDs (including one or more of the LEDs as described above), incandescent light sources (eg, filament lamps, halogen lamps), fluorescent sources, phosphorous light sources, high Luminance discharge sources (eg sodium vapor, mercury vapor, metal halide lamps), lasers, other types of electroluminescence sources, high temperature luminescence sources (eg flames), candle luminescence sources (eg incandescent lamps, carbon arcs) Radiation source), photoluminescence source (eg, gas discharge source), cathodoluminescence source using electron saturation, direct current luminescence source, crystal luminescence source, motion luminescence source, thermoluminescence source, triboluminescence source Should be understood to represent one or more of a variety of radiation sources, including sonoluminescence sources, radioluminescence sources, and luminescent polymers. That.

A given light source may be configured to generate electromagnetic radiation within the visible spectral range, outside the visible spectral range, or a combination of both. Here, the terms “light” and “radiation” are used interchangeably herein. The light source may also have one or more filters (eg, color filters), lenses or other optical components as essential components. It should also be understood that the light source may be configured for a variety of applications including, but not limited to, indication, display and / or illumination. An “illumination source” is a light source that is specifically configured to generate radiation having sufficient intensity to efficiently illuminate an indoor or outdoor space. In this context, “sufficient intensity” refers to illumination around the visible spectrum generated in space or the environment (ie, it can be sensed indirectly or eg one or more before all or part is sensed) Often the unit “lumen” or “beam” is used to represent the total light output in all directions from the light source in terms of radiation output (in terms of radiation output) to provide sufficient light that can be reflected to various intermediate surfaces. Represents).
The term “lighting fixture” is used herein to describe the implementation or configuration of one or more lighting units, assemblies or packages of a particular form factor. The term “lighting unit” is used herein to describe a device that includes one or more light sources of the same or different types. A given lighting unit may have one of a variety of light source implementations, enclosure / housing configurations, and shapes, and / or electrical and mechanical coupling configurations. Also, a given lighting unit is optionally associated (eg, included, combined, and / or packaged together) with various other components (eg, control circuitry) related to the operation of the light source. May be. “LED-based lighting unit” refers to a lighting unit that includes a light source based on one or more LEDs as described above, alone or in combination with other LED-based lighting units. A “multi-channel” lighting unit refers to an LED-based or non-LED-based lighting unit that includes at least two light sources each configured to generate radiation of different spectra. Each of the different light source spectra is referred to as one “channel” of the multi-channel lighting unit.

  The term “control unit” is generally used herein to describe various devices related to the operation of one or more light sources. The controller may be implemented in various ways (such as dedicated hardware) and perform various functions discussed herein. A “processor” is an example of a controller that uses one or more microprocessors that can be programmed using software (eg, microcode) to perform the various functions discussed herein. The controller may be implemented with or without a processor, and may be implemented as a combination of dedicated hardware to perform some functions and a processor (eg, one or more programmed). Other functions may be implemented as a microprocessor and associated circuitry. Examples of controller components that can be used in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

  In various implementations, the processor or controller may include one or more storage media (generally “memory” here, eg, RAM, PROM, EPROM and EEPROM, floppy disk, compact disk, optical disk, magnetic tape section). And so on) (referred to as volatile and non-volatile computer memory, etc.). In some implementations, the storage medium is encoded with one or more programs that perform at least some of the functions discussed herein when executed on one or more processors and / or controllers. Also good. The various storage media may be fixed within the processor or controller, or may be portable so that one or more stored programs can be loaded into the processor or controller, and the various of the present invention discussed herein. The embodiment may be made to be able to be implemented. The term “program” or “computer program” is used herein to represent any type of computer code (eg, software or microcode) that can be used to program one or more processors or controls. Used generically.

  The term “addressable” as used herein is configured to receive information (eg, data) for a plurality of devices, including a device, and selectively respond to specific information for the device. Also used to represent such devices (eg, generally light sources, lighting units or fixtures, controllers or processors associated with one or more light sources or lighting units, other non-lighting related devices, etc.). The term “addressable” is used in reference to a networked environment in which multiple devices are coupled together via one or more specific communication media (or “network”, discussed in further detail below). It is often done.

  In some network implementations, one or more devices coupled to the network may serve as a controller for one or more other devices (eg, in a master / slave relationship). In another implementation, the network coupled environment may have one or more dedicated controls configured to control one or more devices coupled to the network. In general, each of a plurality of devices coupled to a network may have access to data residing on one or more communication media. However, a given device may selectively exchange data with the network (ie, receive data from the network and / or based on one or more specific identifiers (eg, “addresses”) assigned to the device, for example. Or may be “addressable” in that it is configured to transmit to a network.

  The term “network” as used herein refers to the transport of information (eg, device control, data storage, data exchange, etc.) between two or more devices and / or between multiple devices coupled to the network. Ii) represents an interconnection of two or more devices (including a control unit or a processor) that realizes the above. As will be readily appreciated, various implementations of networks suitable for interconnecting multiple devices may use any of a variety of communication protocols, including any of a variety of network technologies. Further, in the various networks of the present disclosure, any one coupling between two devices may represent a dedicated coupling between two systems or alternatively a non-dedicated coupling. In addition to the transmission of information targeted at two devices, the non-dedicated coupling may convey information that is not necessarily targeted at either of the two devices (for example, open network coupling). Further, it should be immediately understood that the various networks of devices as discussed herein can transport information through the network using one or more wireless, wired / cable, and / or fiber optic links. May be realized.

  It should be understood that all combinations of the aforementioned concepts and further concepts discussed in detail below (assuming that these concepts are not in conflict with each other) are the subject matter of the invention disclosed herein. To be considered a part of. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are considered to be part of the inventive subject matter disclosed herein. It should also be understood that the terminology explicitly used herein appears in any disclosure incorporated by reference and is most consistent with the specific concepts disclosed herein. Should be given a certain meaning.

In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead being placed upon being uniform in describing the principles of the invention.
Fig. 2 shows a schematic diagram of a standard lighting system including a leading edge triac dimmer. The output waveform of the leading edge triac dimmer shown in FIG. 1 is shown. Fig. 4 shows the input current and voltage waveforms in a standard lighting system as a result of misignition. 1 is a block diagram of an exemplary embodiment lighting system. FIG. FIG. 5 is a schematic diagram of a bleed circuit which is a typical bleed circuit shown in FIG. 4. 2 shows input current, bleed voltage and voltage waveform in a lighting system of an exemplary embodiment.

  In general, applicants recognize and understand that it is beneficial to ensure that the minimum level of resonant input current in the dimmer is greater than the holding current of the dimmer. When the dimmer ignites, the minimum level of the resonant input current can be boosted to a higher level by adding a DC bias to the resonant waveform at the dimmer input, and the resonant current is kept higher than the holding current, so Prevents mis-ignition of the light source and consequently flickering of the light source. In view of the foregoing, various embodiments and implementations of the present invention relate to methods for removing bleed circuits and flicker. Thereby, the bleed current is controlled to be kept on until resonance of the input current in the dimmer stops.

  FIG. 4 is a block diagram of an exemplary embodiment lighting system. With reference to FIG. 4, the illumination system 400 includes a dimmer 404 coupled to the main voltage 402. Main voltage 402 can provide different unregulated main input voltages, such as 100 VAC, 120 VAC, 230 VAC, and 277 VAC, according to various implementations. The dimmer 404 may be a leading edge triac dimmer, such as the leading edge triac dimmer 104 shown in FIG. 1, but other types of leading edge triac dimmers will be understood by those skilled in the art. It may be configured according to other types of phase cut dimmers, such as an optical device, a leading edge dimmer, or a trailing edge dimmer. The dimmer 404 provides a dimming function by chopping the leading edge of the voltage signal waveform from the main voltage 402 in response to a setting by the system user. The (dimmed) voltage signal is supplied from the dimmer 404 to the rectifier 406. The rectifier 406 supplies the rectified voltage signal to the DC / DC power converter 410 along the DC bus. The power converter 410 outputs a corresponding DC voltage to supply power to a light source 412, shown in this example as including an LED. A bleed circuit 408 is included to be placed in parallel with the light source 412 to draw additional current with the light source 412 and thus increase the load current of the dimmer 404 to a minimum sufficient for operation of the dimmer 404. Can be switched to

  FIG. 5 is a schematic diagram of a bleed circuit 500 that is the representative bleed circuit 408 shown in FIG. In FIG. 5, resistors 502, 504 and 506 and a Zener diode 508 are coupled to each other and configured as a detector that detects the potential of the rectified voltage signal supplied to the DC bus by the rectifier 406. Resistor 502 has a first terminal coupled to the DC bus. Resistor 504 has a first terminal coupled to the second terminal of resistor 502 and Zener diode 508 has a first anode terminal coupled to the second terminal of resistor 504. Has a first terminal coupled to the second cathode terminal of Zener diode 508 and further has a second terminal coupled to ground. A control signal indicating the potential of the rectified voltage signal on the DC bus is considered to be supplied at node N1 between zener diode 508 and resistor 506.

The bleed circuit 500 as shown in FIG. 5 further includes a diode 524, a resistor 526, and a capacitor 528 coupled together to provide a predetermined delay. A second anode terminal of diode 524 is coupled to node N1 and receives a control signal. Capacitor 528 has a first terminal coupled to the second cathode terminal of diode 524 and further has a second terminal coupled to ground. Resistor 526 has first and second terminals coupled to a first anode terminal and a second cathode terminal of diode 524, respectively. As described in more detail below, the resistance value R8 of resistor 526 and the capacitance C1 of capacitor 528 may be selected as predetermined values, and diode 524 delays the control signal at node N1 by a predetermined delay. May be selected.
The bleed circuit 500 shown in FIG. 5 further includes a transistor 510 that may be a bipolar transistor having a base or control terminal coupled to the delay control signal at the first terminal of the capacitor 528. Transistor 510 has an emitter or first terminal coupled to ground and a collector or second terminal coupled to node N2. Node N2 is coupled to the DC bus through series-coupled resistors 512 and 514. Resistor 512 has a first terminal coupled to the DC bus. Resistor 514 has a first terminal coupled to the second terminal of resistor 512 and further includes a second terminal coupled to node N2. Node N2 is also coupled to ground via zener diode 516. Zener diode 516 has a first anode terminal coupled to node N2 and further has a second cathode terminal coupled to ground.

  The bleed circuit 500 of FIG. 5 further includes a transistor 518 that may be, for example, a field effect transistor (FET). The control or gate terminal of transistor 518 is coupled to node N2. Transistor 518 has a first terminal coupled to the DC bus and further has a second terminal coupled to ground through series coupled resistors 520 and 522. Resistor 520 has a first terminal coupled to the second terminal of resistor 518 and resistor 522 has a first terminal coupled to the second terminal of resistor 520 and is connected to ground. It further has a coupled second terminal. Transistor 518 is characterized as a bleed component or transistor that is switchably controlled by the potential at node N2 to provide bleed current from the DC bus through resistors 520 and 522 to the dimmer 404 via the ground return path. Can be. Resistors 520 and 522 limit the current flowing from the DC bus to ground. It should be understood that although transistor 518 is shown as an n-type FET including an intrinsic body diode, transistor 518 can be any metal oxide semiconductor field effect transistor (MOSFET) or gallium arsenide field effect transistor (GaAsFET). There may be other types of FETs, and other types of FETs and / or other types of transistors within the scope of the skilled artisan can be included without departing from the scope of the teachings of the present invention. The transistor 510 is not limited to a bipolar transistor, and may be another type of transistor as described above.

  The operation of the bleed circuit of the representative embodiment will be described below with reference to FIGS. In the initial state before the dimmer 404 is conducting, the bleed circuit 408 of FIG. 4 is kept on to draw current. In the bleed circuit 500 shown in FIG. 5, in the initial state before the dimmer 404 is turned on and conducting, the resistors 502, 504 and 506, and the zener diode 508 are connected to the rectified voltage signal on the DC bus. The potential is detected as relatively low. At this time, the potential detected at node N1 is correspondingly low and the potential at the control terminal of transistor 510 is also low. Transistor 510 is switched off in response to the low voltage. As a result, the potential of the node N2 applied to the control terminal of the transistor 518 is relatively high, and the transistor 518 is turned on. The dimmer 404 is not conducting at this time, but the potential on the DC bus is about 5-10V and keeps the bleed circuit 500 operable. During this period, bleed current is supplied from the DC bus through transistor 518 and resistors 520 and 522 to the dimmer 404 via the return path. Therefore, the return current path of FIG. 4 is maintained at a minimum that is sufficient for the dimmer 404 to operate correctly.

As the potential on the DC bus continues to increase, the dimmer 404 becomes conductive and turns on the light source 412 and the potential detected at node N1 increases accordingly. When the potential on the DC bus becomes higher than the collapse voltage of Zener diode 508, capacitor 528 begins to charge. After a predetermined delay provided by diode 524, resistor 526, and capacitor 528, at certain points, the potential at the control terminal of transistor 510 is high enough to turn transistor 510 on. Correspondingly, the potential at the node N2 drops to near the ground level (about 0.3V), the transistor 518 is turned off, and the bleed current from the DC bus to the return path is cut off . Predetermined delay provided by diode 524, resistor 526 and capacitor 528, delay when the bleed current is cut off.

  Conventional bleed circuits are usually designed to switch the bleed current off when the dimming circuit is on. In contrast, the bleed circuit 500 of the exemplary embodiment of FIG. 5 has a diode 524, a resistor 526, and a resistor 526 configured to provide a predetermined delay that delays turning off the transistor 510 in response to a control signal. A capacitor 528 is included. The delay amount or delay time provided by the diode 524, resistor 526, and capacitor 528 of FIG. 5 is set according to the expected time period or length of resonance of the input current supplied to the dimmer 404. The predetermined delay time is selected to be longer than the period of resonance. The period of resonance of the input current is typically about 200-500 microseconds.

  Transistor 518 is controlled to turn on to provide bleed current to dimmer 404 via a return current path for a predetermined time after dimmer 404 is turned on, longer than the period of resonance. During the time period, the input current at the light source is boosted. A bleed current of DC current of about several hundred milliamps raises the input current in the dimmer 404 higher than the holding current of the dimmer 404. The dimmer 404 is kept on until after the resonance of the input current in the dimmer 404 ends. Thus, during the half-wave period, mis-ignition of the leading edge triac dimmer 404 and the resulting light source flicker are prevented. This can be understood in view of FIG. FIG. 6 shows the ignition current C2 at the light source, the bleed voltage C3, and the input voltage C4 at the DC bus. The ignition current C2 shown in FIG. 6 is switched on only once during each individual half-wave period and cannot be repeatedly switched on and off during the half-wave period.

  In the exemplary embodiment, when the input voltage is 120 V / 60 Hz in the lighting system described above with respect to FIGS. 4 and 5, the resistance values R1 and R2 of resistors 502 and 504, respectively, are both selected to be about 250 kΩ and the resistance The resistance value R3 of the resistor 506 is selected to be about 100 kΩ, the resistance value R8 of the resistor 526 is selected to be about 2.2 MΩ, and the resistance values R4 and R5 of the resistors 512 and 514 are both about 150 kΩ. The resistance values R6 and R7 of the resistors 520 and 522, respectively, may be selected to be about 680Ω. Capacitance C1 of capacitor 528 may be selected to be about 10 nF. The diode 524 may be a 1N4148 diode. The zener breakdown voltage Z1 of the zener diode 508 may be selected to be about 6.8V. The zener breakdown voltage Z2 of the zener diode 516 may be selected to be about 10V. According to this example, the charging time for capacitance 528 is approximately 200-500 microseconds to keep bleed circuit 500 on for the expected time period or length of the input current resonance at the light source. However, it should be understood that the above values are given as examples only, and as will be apparent to those skilled in the art, various other resistance values, capacitances, zener breakdown voltages and diodes may be used for various implementation applications. It may be selected to meet specific design requirements.

  While several embodiments of the present invention have been described and illustrated herein, one of ordinary skill in the art may perform the functions described herein and / or obtain one or more of the results and / or advantages. Various other means and / or structures will immediately be envisioned. More generally, those skilled in the art will appreciate that all parameters, dimensions, materials and configurations described herein are examples, and that actual parameters, dimensions, materials and / or configurations are within the teachings of the present invention. It will be readily appreciated that it depends on the particular application or applications used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Accordingly, the foregoing embodiments have been presented by way of example only, and embodiments of the invention may be practiced within the scope of the claims and their equivalents, except as specifically described and claimed herein. It should be understood that this can be done. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and / or method described herein. Further, any combination of two or more of such features, systems, articles, materials, kits and / or methods is disclosed if the features, systems, articles, materials, kits and / or methods do not conflict with each other. Are included in the scope of the present invention.

  All definitions should be understood as governing the definition of a dictionary, definitions in a document incorporated by reference, and / or the ordinary meaning of a defined term, as defined and used herein. is there.

  The indefinite article “a” (“a” and “an”), as used in the specification and claims, should be understood to mean “at least one” unless expressly specified otherwise. .

  In any method claimed herein involving more than one step or action, unless otherwise expressly indicated, the order of the steps or actions of the method is not necessarily limited to the order in which the steps or actions of the method are described. It is understood that it will not.

  Any reference signs or symbols appearing in parentheses in the claims are provided for convenience only and do not limit the claims in any way.

  All intermediate phrases such as “comprising, including, having, containing, containing, involving, holding, proposed of” etc. in the claims as well as in the specification Should be considered unconstrained, ie, but not limited to. Only the intermediate phrase “consisting of, essentially consisting of” is a limiting or semi-limiting intermediate phrase, respectively.

Claims (17)

A bus configured to provide a voltage signal from the dimmer and dimmably adjust the light output by the light source ;
A detection circuit configured to detect the potential of the bus and supply a control signal in response to the detected potential ;
A bleed component configured to supply a bleed current from the bus to the dimmer via a return current path ;
Delaying the control signal by a predetermined delay, supplying the delayed control signal to the bleed component, and responding to the delayed control signal until the resonance of the input current in the dimmer is completed. A delay circuit configured to supply the bleed current ;
I have a,
The delay circuit is
A diode having a first terminal coupled to the detection circuit for receiving the control signal and a second terminal;
A resistor having first and second terminals respectively coupled to the first and second terminals of the diode;
A capacitor having a first terminal coupled to the second terminal of the diode and a second terminal coupled to the return current path;
Have
The bleed circuit , wherein the delayed control signal is supplied from the first terminal of the capacitor to the bleed component .   The bleed circuit of claim 1, wherein the light source comprises at least one light emitting diode.   The bleed circuit of claim 2, wherein the dimmer is a leading edge dimmer.   4. The bleed circuit of claim 3, wherein the leading edge dimmer has a triac. The bleed circuit according to claim 1, wherein the resistor and the capacitor of the delay circuit constitute an RC circuit, and the predetermined delay is set according to a time constant of the RC circuit.   6. The bleed circuit of claim 5, wherein the predetermined delay is in a range of about 200 microseconds to 500 microseconds. It said bleed component,
A control transistor having a control terminal coupled to the delayed control signal, a first terminal coupled to a first node, and a second terminal coupled to the return current path ;
A first resistor network having a first terminal coupled to the bus and a second terminal coupled to the first node ;
A Zener diode having a first terminal coupled to the first node and a second node coupled to the return current path ;
A first transistor having a control terminal coupled to the first node, a first terminal coupled to the bus, and a second terminal ;
A second resistor network having a first terminal coupled to the second terminal of the first transistor and a second terminal coupled to the return current path ;
The bleed circuit according to claim 1 , comprising: A system for controlling power distributed to a light source, the system comprising :
Coupled to the main voltage, configured dimmer so supplies a voltage signal for adjustably controlling the light output by the light source,
A rectifier circuit configured to supply a rectified voltage signal to the bus in response to the voltage signal ;
A bleed circuit configured to supply a bleed current to the dimmer via a return current path ;
A power converter configured to drive the light source in response to the rectified voltage signal ;
Have
The bleed circuit is further configured to supply the bleed current in response to a control signal until resonance of the input current in the dimmer stops .
The bleed circuit is
A detection circuit configured to detect a potential of the bus and supply a first control signal in response to the detected potential;
A bleed component configured to supply the bleed current from the bus to the dimmer via the return current path;
Delaying the first control signal by a predetermined delay, supplying the delayed control signal to the bleed component, and responding to the control signal until the resonance of the input current in the dimmer is completed. A delay circuit configured such that a component supplies said bleed current;
Have
The delay circuit is
A diode having a first terminal coupled to the detection circuit for receiving the control signal and a second terminal;
A resistor having first and second terminals respectively coupled to the first and second terminals of the diode;
A capacitor having a first terminal coupled to the second terminal of the diode and a second terminal coupled to the return current path;
Have
Control signal the delay Ru is supplied to the bleed components from said first terminal of said capacitor, system. The system of claim 8 , wherein the light source comprises at least one light emitting diode. The system of claim 9 , wherein the dimmer is a leading edge dimmer. The system of claim 10 , wherein the leading edge dimmer comprises a triac. 9. The system according to claim 8 , wherein the resistor and the capacitor of the delay circuit constitute an RC circuit, and the predetermined delay is set according to a time constant of the RC circuit. The system of claim 12 , wherein the predetermined delay is in a range of about 200 microseconds to 500 microseconds. It said bleed component,
A control transistor having a control terminal coupled to the control signal, a first terminal coupled to a first node, and a second terminal coupled to the return current path ;
A first resistor network having a first terminal coupled to the bus and a second terminal coupled to the first node ;
A Zener diode having a first terminal coupled to the first node and a second node coupled to the return current path ;
A first transistor having a control terminal coupled to the first node, a first terminal coupled to the bus, and a second terminal ;
A second resistor network having a first terminal coupled to the second terminal of the first transistor and a second terminal coupled to the return current path ;
The bleed circuit according to claim 8 , comprising: A method for removing flicker from the light emitted by the light emitting diode, the method comprising:
Supplying a voltage signal from the dimmer via a bus to dimmably adjust the light output by the light emitting diode ;
A detection circuit supplying a control signal in response to the detected potential of the voltage signal ;
A bleed component supplying a bleed current from the bus to the dimmer via a return current path ;
A delay circuit delaying the control signal by a predetermined delay to provide a delayed control signal ;
Have
The bleed current is supplied to the dimmer in response to the delayed control signal until resonance of the input current in the dimmer stops .
The delay circuit is
A diode having a first terminal for receiving the control signal and a second terminal;
A resistor having first and second terminals respectively coupled to the first and second terminals of the diode;
A capacitor having a first terminal coupled to the second terminal of the diode and a second terminal coupled to the return current path;
Have
Control signal the delay Ru is supplied to the bleed components from said first terminal of said capacitor, the method. The method of claim 15 , wherein the dimmer is a leading edge dimmer with a triac. Step of the delay, the offered by the RC circuit constituted by the diode and the resistor and the capacitor of the delay circuit, wherein the predetermined delay is set in accordance with the time constant of the RC circuit, according to claim 15 the method of.

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