Patent Application
20150195880
The present application relates to an apparatus for providing intelligence to a lighting system, and more particularly, to an apparatus for providing dimming control to a lighting system.
Over the years lighting system technology has advanced manyfold. Energy conservation in lighting systems plays a vital role in generating effective illumination, besides being cost effective. Without compromising on ambience, visual comforts and aesthetics, it is also a requisite to integrate light system-designs with economics and environment.
Of late, different light sources have come up and been replaced by improved variants. Prominent among them have been Incandescent lamps, Gas-discharge bulbs, Fluorescent Lamps and Light Emitting Diodes, to name a few. Certain factors like life-span of the light source, light distribution, light diffusion, sensitivity to temperature and humidity and operational cost are crucial in determining reliability of lighting systems.
Light emitting diodes lamps are more energy efficient as compared to other conventional source of lighting. A trend of replacing conventional lamps with the LED retrofit lamp is getting more and more popular.
Since energy conservation and management of electrical power is a growing concern with regard to both cost and environmental impact, the LED retrofit lamp technology therefore requires further improvement. Therefore a system is required that enables the user to harvest substantial portion of energy from the existing LED lamp circuit and to provide intelligent built-in features for controlling the wastage of energy.
Environment responsive intelligence in LED retrofits may further enhance energy management by drastically reducing wasteful consumption. Public spaces can be monitored on the basis of specific environmental stimuli like occupancy and time-clocks, so as to yield optimum light. This can bring significant improvement in user comfort and energy savings in commercial and industrial applications.
The present invention provides a controlling apparatus and method for providing intelligence to a retrofit lamp. The retrofit lamp having an array of LEDs is connected to the controlling apparatus. The controlling apparatus comprises a sensor means to monitor the required lighting parameters, a dimming control to control the brightness of the retrofit lamp in response to the parameters monitored by the sensor means, a power harvesting mean for harvesting power from the existing circuit, a micro-controller that creates a pulse width modulation in response to being asserted that in turn reduces the string length and the lamp power, a field effect transistor (FET) connected in parallel to the LED array such that the field effect transistor (FET) control the forward voltage of the retrofit lamp, a communication device to receive the instructions from the user, an external interface that receives the instruction from the sensor means or the communication device and controls the forward voltage of the retrofit lamp.
The subject invention modifies the conventional technology and saves power by introducing a dimming control that dims the light emitting diode output from 100% to 15% in response to external or internal stimuli.
The controlling apparatus has the ability to harvest a small amount of DC power from the constant current ballast to drive internal and external components. A set of series LED in the LED array is left on and the power is harvested in parallel from the set of series diode for the micro controller and the external lamp of up to 5V/100 mA. Using the field effect transistor the forward voltage of the light emitting diode array is controlled with the help of the microcontroller that creates a pulse width modulation signal at a frequency of approximately 1 KHz that enables the field effect transistor to reduce the string length and lamp power in response to overheating and external dimming signal. The sensor means receives the power harvested from the lamp and is then able to control the lamp dimming. This sensor means may be autonomous such as an occupancy or photo sensor, may be a modem allowing control at a higher level or may be a combination of sensors and a modem.
The preferred embodiment of the invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the invention, wherein like designation denote like element and in which:
In the following detailed description of embodiments of the invention, numerous specific details are set forth in order to provide a thorough understanding of the embodiment of invention. However, it will be obvious to a person skilled in the art that the embodiments of invention may be practiced with or without these specific details. In other instances well known methods, procedures and components have not been described in detail so as not to unnecessarily obscure aspects of the embodiments of the invention.
Furthermore, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art, without parting from the spirit and scope of the invention.
The present invention provides a lighting system with built-in intelligence features to allow it to dim itself in response to autonomous or external stimuli and to harvest power for the internal and external circuit. The lighting system comprises a LED lamp driven by a ballast and a controlling unit that imparts a built-in intelligence system to the LED lamp. The circuit of the lighting system comprises a LED lamp having an array of light emitting diodes, wherein one set of the series diodes is left on and the power is harvested, in parallel from the set of series diode. A field effect transistor (FET) is wired in parallel with a portion of the light emitting diode array; the field effect transistor controls the forward voltage of the LED lamp. The Field Effect Transistor, when turned off, exposes the full light emitting diode array and the maximum forward voltage to the LED lamp. Similarly field effect transistor, when turned on, short circuits many of the light emitting diodes and reduces the forward voltage and the power drawn from the ballast.
The embodiments of the present invention comprise a controlling apparatus with an 8 bit micro controller, a power conditioning circuitry such as a Low Dropout Regulator (LDO) to regulate power to the peripheral interface controller (Microcontroller unit) and an external interface.
In an embodiment of the invention, the controlling unit 103 may enable additional functionality to the LED lamp 102 such as power reduction for thermal management, top trimming at factory via the controlling unit 103, and top trimming in field via circuit switching or other stimulus. Furthermore, a single controlling unit 103 can control a plurality of LED lamps 102. The lamp may be circuit switched via the controlling unit 103, in addition to being locally controlled. The controlling unit 103 further comprises a means for sensing the ambient parameters such as an occupancy sensor or a photo sensor. The controlling unit 103 further comprises a modem that allows control at a higher level or may comprise of a combination of the sensors and the modem.
The controlling unit 103 is further connected to an external monitoring device such as an occupancy sensor or a photo sensor. The controlling unit 103 receives the input from the monitoring device and controls the dimming of the LED lamp 102. The occupancy sensor is a lighting control device that detects occupancy of a space by people and turns the lights on or off automatically, using infrared or ultrasonic technology. The energy saved by the occupancy sensors provides automatic control over lighting and complies with the building's codes.
In an embodiment of the present invention the controlling unit 103 harvests a small amount of DC power from the constant current supplied by the non-dimmable ballast 101. The harvested power is then used to drive the external and internal electronics of the controlling unit 103 as well as the monitoring device. Thus there is no need of providing extra power to the controlling unit 103.
In another aspect of the present invention, the controlling unit 103 further comprises a means to control the forward voltage to the LED lamp 102 that enables the dimming of LED lamp 102 in response to external stimuli.
The controlling unit 103 contains a power harvesting means 203 that harvest the power simultaneously from the LED lamp 102. The LED lamp 102 contains a series of LED array 308 that always remains in an ON position; a circuit is extended parallel from the LED strings from where power is drawn to the power harvesting means 203 in the controlling unit 103 using the micro USB cable 104 and the connection interface 208. The power harvesting means 203 in the controlling unit 103 stores the power and uses it for driving the internal components of the controlling unit 103 as well as for feeding power to the monitoring sensors 209. The use of power harvesting means 203 eliminates the need of extra source of power for driving the controlling unit 103.
In an embodiment of the present invention, the connection interface 208 is connected to the LED lamp 102 through the cable 104 which is class 2 type. The cable 104 comprises a micro USB cable, RJ11, RJ14, RJ21, RJ45, RJ48 or other known class 2 type cables.
The Field Effect Transistors 204 and 207 present in the controlling unit 103 control the forward voltage to the LED lamp 102. The field effect transistors 204 and 207 are circuited in parallel with the portion of LED array 308. Turning the field effect transistors 204 and 207 off exposes the full LED array 308 and thus maximum forward voltage to the LED lamp 102. On turning the field effect transistors 204 and 207 ON, many of the LEDs get short circuits thereby reducing the forward voltage and power drawn from non-dimmable ballast 101.
The dimming control 205 in the controlling unit 103 controls the illumination intensity of LED lamp 102. The microcontroller 202 receives the input from monitoring sensors 209 and on receiving the input instructs the dimming control 205 to control the output to the LED lamp 102. The dimming control 205 then sends instruction to the field effect transistors 204 and 207 to reduce the forward voltage to LED lamp 102.
In another embodiment of the present invention, the forward voltage to the LED lamp 102 is controlled by placing a series of FET connected in parallel to the LED array. On receiving an input from the dimming control 205, the microcontroller 202 decides the number of FETs to remain in ON position. Each FET in the series is having an extra LED connected to the series. Depending on the instructions received from the microcontroller 202, the FETs in series turn ON additional LEDs thus regulating the forward voltage to the LED lamp 102.
In an embodiment of the present invention, the lighting system further comprises a thermistor 201 that monitors the temperature of the LED lamp circuit 102. The thermistor 201 may be present in the LED lamp 102 or it may be in the controlling unit 103. In case of overheating, the thermistor 201 senses the temperature and sends the feedback to the microcontroller 202. The microcontroller 202 then instructs the field effect transistors 204 and 207 to regulate the forward voltage in the event of the overheating of circuit.
In another embodiment of the present invention the controlling unit 103 further comprises a communication means 206 such as a modem or a radio frequency means. The communication means 206 is connected to the microcontroller 202. The user can send his instructions to the microcontroller 202 using the communication means 206.
The invention finds lightening application in various areas like indoor light, outdoor light and various other decoration or ornamental light, power reduction for thermal management. The lighting system has ability to harvest a small amount of DC power from the constant current AC ballast to drive internal and external electronics.
