Patent Application
20140265922
The inventive subject matter relates to lighting apparatus and methods and, more particularly, to solid-state lighting apparatus and methods.
Solid-state lighting arrays are used for a number of lighting applications. For example, solid-state lighting panels including arrays of solid-state light emitting devices have been used as direct illumination sources in architectural and/or accent lighting. A solid-state light emitting device may include, for example, a packaged light emitting device including one or more light emitting diodes (LEDs), which may include inorganic LEDs, which may include semiconductor layers forming p-n junctions and/or organic LEDs (OLEDs), which may include organic light emission layers.
Solid-state lighting devices are often used in lighting fixtures, such as incandescent bulb replacement applications, task lighting, recessed light fixtures and the like. For example, Cree, Inc. produces a variety of light fixtures that use LEDs for illumination. The fixtures include can-type down lights, such as the LR-6 and CR-6, and troffer-type fixtures, such as the CR-24.
LEDs can be dimmed using, for example, linear dimming or pulse-width modulated (PWM) dimming. In a typical LED lighting apparatus, a microcontroller generates a PWM signal that is provided to a driver circuit that controls current passing through one or more LEDs. By varying the duty cycle of the PWM signal, the average current of the LEDs is proportionally changed, and the brightness of the LEDs varies accordingly.
Some conventional microcontroller-based dimming controllers implement linear dimming. Typically, the microcontroller samples a dimming control signal (e.g., from a commercial dimmer) and generates a PWM signal with its duty cycle varying with the dimming control signal. The PWM signal may be filtered with a low-pass filter, producing a DC voltage that is used to control a power stage of the driver circuit to adjust the LED current.
Some embodiments provide a lighting apparatus including at least one light emitting device and a reconfigurable driver circuit configured to drive the at least one light emitting device with an intensity that varies responsive to a dimming signal according to an adjustable mapping of the dimming signal to output of the light emitting device. In some embodiments, the mapping may be configurable using circuit component selection. In further embodiments, the mapping may be provided by a data input.
In some embodiments, the driver circuit may include an analog filter that provides the mapping, which may be configurable by selection of a component of the analog filter, such as a feedback component. In some embodiments, the component selection may include a selection from a plurality of candidate components present in the driver circuit using, for example, one or more switches, fuses or other selection devices. In further embodiments, the component selection may include a component replacement in the driver circuit.
In some embodiments, the driver circuit may include a processor configured to control dimming of the at least one light emitting device, and a data input to provide a dimming mapping may include a data input for the processor. In some embodiments, the data input may include a lookup table. In further embodiments, the data input may include at least one parameter of a mathematical function that relates the dimming signal to light intensity. The at least one parameter may include at least one value of the mathematical function and/or a coefficient of the mathematical function.
In some embodiments, the reconfigurable driver circuit may include a reconfigurable dimming mapping circuit configured to receive a first dimming signal and to generate a second dimming signal according to the adjustable mapping and a driver circuit configured to receive the second dimming signal and to vary illumination intensity of the at least one light emitting device responsive thereto. In some embodiments, the dimming mapping circuit may include a reconfigurable analog filter circuit configured to generate the second dimming signal. In some embodiments, the dimming mapping circuit may include a processor circuit configured to generate the second dimming signal.
According to some embodiments, the first dimming signal may include a phase cut dimming signal and the dimming mapping circuit may include an average circuit configured to receive the phase cut dimming signal and to generate an average signal therefrom and a reconfigurable mapping circuit configured to receive the average signal and to generate the second dimming signal therefrom according to the adjustable mapping.
Further embodiments of the inventive subject matter provide an apparatus including an input configured to receive a dimming signal, an output configured to be coupled to at least one lighting device and a reconfigurable driver circuit coupled to the output and configured to drive the at least one light emitting device with an intensity that varies responsive to the dimming signal according to an adjustable mapping. The mapping may be configurable using circuit component selection and/or a data input.
The reconfigurable driver circuit may include a reconfigurable dimming mapping circuit configured to receive a first dimming signal and to generate a second dimming signal according to the adjustable mapping and a driver circuit configured to receive the second dimming signal and to vary illumination intensity of the at least one light emitting device responsive thereto.
In additional embodiments, an apparatus includes an input configured to receive a dimming signal, an output configured to be coupled to at least one lighting device and a reconfigurable dimming mapping circuit coupled to the output and configured apply an adjustable mapping to the received dimming signal to provide a remapped dimming signal to the at least one lighting device. The mapping may be configurable using circuit component selection and/or a data input. The apparatus may be configured as a module configured to interface a dimmer to the at least one lighting device.
The accompanying drawings, which are included to provide a further understanding of the inventive subject matter and are incorporated in and constitute a part of this application, illustrate certain embodiment(s) of the inventive subject matter. In the drawings:
Embodiments of the inventive subject matter now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the inventive subject matter are shown. This inventive subject matter may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive subject matter to those skilled in the art. Like numbers refer to like elements throughout.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the inventive subject matter. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. It will be further understood that elements “coupled in series” or “serially connected” may be directly coupled or may be coupled via intervening elements.
Spatially relative terms, such as “below”, “beneath”, “lower”, “above”, “upper”, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. Throughout the specification, like reference numerals in the drawings denote like elements.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive subject matter. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive subject matter belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. The term “plurality” is used herein to refer to two or more of the referenced item.
The expression “lighting apparatus”, as used herein, is not limited, except that it indicates that the device is capable of emitting light. That is, a lighting apparatus can be a device which illuminates an area or volume, e.g., a structure, a swimming pool or spa, a room, a warehouse, an indicator, a road, a parking lot, a vehicle, signage, e.g., road signs, a billboard, a ship, a toy, a mirror, a vessel, an electronic device, a boat, an aircraft, a stadium, a computer, a remote audio device, a remote video device, a cell phone, a tree, a window, an LCD display, a cave, a tunnel, a yard, a lamppost, or a device or array of devices that illuminate an enclosure, or a device that is used for edge or back-lighting (e.g., back light poster, signage, LCD displays), bulb replacements (e.g., for replacing AC incandescent lights, low voltage lights, fluorescent lights, etc.), lights used for outdoor lighting, lights used for security lighting, lights used for exterior residential lighting (wall mounts, post/column mounts), ceiling fixtures/wall sconces, under cabinet lighting, lamps (floor and/or table and/or desk), landscape lighting, track lighting, task lighting, specialty lighting, ceiling fan lighting, archival/art display lighting, high vibration/impact lighting, work lights, etc., mirrors/vanity lighting, or any other light emitting device. The inventive subject matter may further relate to an illuminated enclosure (the volume of which can be illuminated uniformly or non-uniformly), including an enclosed space and at least one lighting apparatus according to the inventive subject matter, wherein the lighting apparatus illuminates at least a portion of the enclosed space (uniformly or non-uniformly).
Some embodiments of the inventive subject matter arise from a realization that in lamp replacement applications, such as those that substitute LED lamps for incandescent or fluorescent lamps, it may be desirable to match dimming characteristics of the replacement lamp with that of the lamp being replaced. According to some embodiments, this may be achieved by using a reconfigurable dimming mapping that may be adjusted to provide desired dimming characteristics for various applications.
Referring to
Referring to
The dimming mapping parameters may be provided, for example, as a data input to a memory (e.g., EPROM, EEPROM, flash memory, or the like) incorporated in and/or accessed by the microcontroller 420.” The mapping parameters may be programmed as a part of a calibration process during production. In some embodiments, a lamp or other lighting device may be designed to flexibly serve in multiple different replacement applications, and dimming mapping parameters may be programmed into the device during production based on the application for which the device is intended for use. The mapping parameters may also be programmed after deployment in the field, manually (e.g., by users or service personnel) and/or remotely via wireless or other communications channels.
In various embodiments, the mapping provided by a microcontroller or other data processing device used to provide dimming mapping may be implemented in any of a number of different ways. For example, the microcontroller 420 may store or access a lookup table that indexes values of the average signal vin to duty cycle values for the PWM dimming signal. In some embodiments, the microcontroller 420 may store or access a parametric formula, e.g., a polynomial, logarithmic or other function, that provides the dimming mapping, which may be adjusted by providing different coefficient sets for use in the formula. The dimming mapping parameters applied by the microcontroller 420″ may be set of coordinate values, and the microcontroller 420′ may use curve fitting and/or interpolation techniques to generate a dimming mapping from these values.
In further embodiments, adjustable dimming mapping may be provided for dimming signals other than phase cut dimming signals. For example, as shown in
Still further embodiments may use reconfigurable converters, such as delta-sigma converters, to implement adjustable dimming mapping.
The input/output mapping provided by the converter 1500 may be varied by varying one or more parameters of the converter 1500. Such parameters may include, for example, the feedback current magnitude Id, the integrator capacitance C, the comparator reference voltage Vref and the frequency of the clock signal CLK. These parameters may be adjusted, for example, responsive to one or more control signals. For example, the feedback current magnitude Id may be adjusted responsive to a bias voltage or other control signal applied to the current source circuit 1552, and the integrator capacitance C may comprise, for example, a capacitor bank and/or varactor that may be adjusted responsive to a control signal. One or more of these parameters may also be a function of a dimming command signal.
Such delta-sigma converter based circuits may be used in a number of different ways in various embodiments. For example, as shown in
Some embodiments of the inventive subject matter may be implemented as part of a lighting fixture or other lighting unit, e.g., integrated with driver, power supply and/or other components. As shown in
It will be appreciated that the adjustable dimming mapping circuitry described above is provided for purposes of illustration, and that some embodiments of the inventive subject matter may use other circuit implementations. For example, analog and/or digital implementations may provide mappings that are dependent upon reference or command voltages and/or currents that are provided to the mapping circuitry.
In the drawings and specification, there have been disclosed typical embodiments of the inventive subject matter and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the inventive subject matter being set forth in the following claims.
