From Issue Five of Gear Patrol Magazine.
Discounted domestic shipping + 15% off in the GP store for new subscribers.
Before electricity, interiors were illuminated by flame, with candles and gas lamps that cast a natural glow. These days, however, high-impact, low-energy bulbs that use blue wavelengths to brighten light — such as LEDs and compact fluorescents — are standard in homes across the globe.
While blue light may assist in matters of alertness and productivity, overexposure can strain retinas and knock the body’s circadian rhythm out of sync. Bulbs that stray from the conventional soft white watt LED, then, have the power to improve overall well-being, joining energy efficiency with the warm glow of a candle.
LIFX A19 LED Light
The LIFX smart bulb boasts fully customizable full-spectrum color — 16 million hues in total — with a color temperature that spans a soft, yellowed hue at 2, kelvins to a vibrant, bluish white at 9, kelvins. Going one step beyond customized “sleep” and “wake” times, an app-enabled Solar Schedule setting uses location-based data to sync the light with the rising and setting sun, gradually glowing brighter to facilitate smoother mornings, and later dimming to conduce a better night’s sleep.
Buy Now: $52
Lighting Science HealthE Good Night LED Sleep-Enhancing Light
The Lighting Science HealthE Good Night bulb was developed in collaboration with NASA to support the circadian rhythms of astronauts aboard the International Space Station. With patented light spectrum technology that filters out 95 percent of blue light, the bulb relies on a warm, pink-yellow glow to foster the natural production of melatonin.
Buy Now: $15
Luminance ST19 Filament LED Bulb
Guided by aesthetics rather than science, a filament bulb encourages relaxation in much the same way that a purpose-built bulb can. Illuminating with lumens, compared to the of a standard watt LED, the Luminance ST19 Filament LED is distinguished by a warm, amber-tinged glow. It clocks in at 2, kelvins, and is perhaps best placed in an exposed light fixture, whether that’s a pendant, flush mount or simple shade-free lamp.
Buy Now: $26
Read More in Gear Patrol Magazine
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USB2 - Switchable luminance LED light bulb - Google Patents
The present application claims priority to, and the benefit of the following applications that are entirely incorporated by reference to the fullest extent allowable by law: U.S. application No. 61/, filed 6 Jun. titled ‘Switchable LED Light Bulb’ and U.S. application No. 61/, filed 4 Jul. titled ‘Switchable Luminance LED Light Bulb’.
The presently disclosed subject matter is directed towards LED-type light bulbs. More particularly the presently disclosed subject matter relates to LED-type light bulbs that have switch controlled illumination intensities.
While white light LED light bulbs have proven to be highly successful they have lacked one feature available in traditional incandescent light bulbs: the ability to provide multiple light outputs from one lamp. For example, 3-way Edison light bulbs are widely used to provide switchable light outputs. A 3-way Edison light bulb could use switched filaments to produce the light output of a Watt, a watt or a watt light bulb. This feature has proven to be extremely popular and useful. In view of the foregoing, white light LED light bulbs having switch-selectable light outputs would be useful and commercially desirable. Even more useful would be white light LED light bulbs having switch-selectable light outputs and which mate with Edison, screw or bayonet fixtures.
The present invention provides an LED bulb (‘the device’) with switch-selectable light outputs. The bulb may be mated with Edison, screw or bayonet types of lamp base fixtures. It is understood in the present disclosure that when an Edison fixture is mentioned as an example, the applicant is only using this as an example and implicitly includes all other types of fixtures such as screw or bayonet types.
The invention provides a low-power, transformerless, LED light bulb power supply capable of providing varying levels of electric current capable of powering variable numbers of LESd to produce proportionally varying levels of light. The invention allows any lamp using a standard Edison, screw bayonet type base to become an arbitrary-way lamp. This is similar to the common ‘3-way’ lamp, but with the following key differences: (a) no specialty lamp is required, (b) no specialty 3-way bulb is required. The invention is different from a standard ‘dimmable’ bulb. It allows for a bulb to have as many discrete light output steps as desirable. The inventors' early prototype was capable of producing light equivalent to a 40 W or 60 W incandescent bulb using a switch to select between lighting levels. Commercially the invention allows the manufacturer to produce one design in mass quantity that will fit many needs. Due to the low power (below 10 W) property of the LED light bulb, this invention is an appropriate replacement for almost any standard light bulb. When any standard bulb fails it could simply be replaced with a bulb of the invention and the user could set the desired lighting output at the time of installation. Therefore only one type of bulb need be purchased to replace a range of old standard bulbs.
The present invention encompasses a switchable luminance LED light bulb device comprising a rectifier to rectify AC to DC, wherein the DC current is fed into a switch, the switch having a single input pole and multiple output poles and a plurality of selectable positions, wherein the switch directs the current through one of a plurality of selectable resistors and/or capacitors corresponding to one of a plurality of different DC output currents, wherein the selected DC output current is fed into at least one of a plurality of light emitting diodes, wherein the selected DC output current corresponds to the light output of the light emitting diodes.
In certain embodiments the device will include a switch that can direct the current through a number of resistors, with no switchable selection of capacitors. In other embodiments, in order to increase the range of current and therefore light output, the device includes a switchable selection of capacitors. In this embodiment, an operator may select a combination of capacitors and resistors. The capacitor switch may be placed ‘upstream’ of the resistor switch, so that the current is first routed to one of a plurality of capacitors, each of which is may be associated with two or more resistors (for example 3, 4, 5, 6 or more resistors). Each capacitor is associated with two or more resistors so as to provide a graduated increase or decrease in current and therefore luminescence.
A current regulating device may be integrated into the device, and may be, in certain embodiments a step-down constant current controller. The device may comprise a current-regulating device and at least one transistor, wherein the current regulating device modulates the gate of the output transistor by reading the voltage, thereby regulating current delivered to LEDs.
In some embodiments the transistor may be, but is not necessarily, a field-effect transistor. In some embodiments it may be a MOSFET.
The present invention provides a white LED (light Emitting Diode) light bulb having a plurality of (two or more) white LEDs for emitting light. In some embodiments the LED light bulb includes an Edison-style screw cap for screwing into an Edison style base to receive input AC electrical power. However, the present invention is applicable to light bulbs with other types of caps for fitting other types of bases. A driver cover may be attached at one end to the Edison-style cap. The driver cover may include an opening for an actuator (any component that may be physically manipulated into different positions such as a switch, a slider, or a plurality of push-buttons) or a multiple-throw switch to pass through the driver cover, which enables a user to change the switched pole. In some embodiments the actuator need not be manually operable by the user, but may be operable remotely through a wired connection or a wireless connection employing widely known circuit technology.
A driver board retaining the switch may be at least partially located within the driver cover such that the switch passes through the opening. The driver board receives the input AC electrical power, rectifies that input AC electrical power into DC electrical power, and applies a constant DC current to the array of LEDs such that the applied current functionally depends on the selected pole position of the switch, and thus the light output functionally depends on the selected pole position.
In one embodiment the invention provides an LED light bulb, comprising one or more (in some embodiments two or more) LEDs for emitting a number of different light outputs of different intensity, for example either a first light output or a second light output; a cap for attaching to a base to receive input AC electrical power; a driver cover attached at one end to the cap, the driver cover having an opening through which a switch protrudes and is accessible; and a driver board having a switch having at least two positions selectable by an actuator that passes through the opening and is accessible to a user to change the switch position. The driver board further includes components capable of receiving input AC current, and rectifying the input AC current to produce a DC current of either a first magnitude or a second magnitude selected by the switch (pole) position.
In one embodiment the device comprises two strings of LEDs in parallel, and both strings are always powered. The current to each string is reduced in the lower lighting mode.
The DC current is applied to at least one LED wherein the LED(s) produce a first lumen output when said first DC current is applied or optionally, a second lumen output when said second DC current is applied; and wherein both first and second DC currents are sufficient to cause said at least one LED to emit light.
In certain embodiments the switch may be switchable to two or more positions, for example 1, 2, 3, 4, 5 or more switch positions, each associated with a different DC current, and therefore each associated with a different brightness (output value) of the one or more LEDs. In some embodiments all positions and all DC currents are sufficient to produce light from the LED. In other embodiments at least one position prevents the flow of current to the LED such that the LED produces no light (the “off” position).
Other embodiments include the LED light bulb wherein said cap is an Edison-style screw cap. Other embodiments use a non-Edison screw cap and may be suitable for attachment to any standard or non-standard electrical fixture. The LED may emit white light or a colored light. The light bulb may comprise a plurality of LEDs mounted on a light engine board. The switch may be a multiple pole slide switch or any other type of suitable switch including a push button, a rocker or a touch sensitive switch. The LED light bulb may include a light diffuser, and/or heat sink in thermal communication with said at least one LED. The driver board may include a switch having at least three selectable positions corresponding to three different DC currents, or in some embodiments a switch having between, for example, two and 10 selectable positions corresponding to between 2 and 10 different DC currents. Other numbers of alternative positions are possible and commonly 2 or 3 switch positions are provided. Alternatively at least 4, 5, 6 7, 10, 15, 20, 25, at least 50 or more switch positions may be provided. In some embodiments the LED light bulb may have a driver board comprising a switch having at least three selectable positions, one of which corresponds to an “off” position whereby no light is provided from one or more of the LEDs.
The present invention, though apparently simple in hindsight, is both novel and of great commercial value, and includes several technical features that are transformative in their effect, turning a simple LED light into a multiple-intensity light bulb, easily switchable between light intensities.
In the figures like numbers refer to like elements throughout. Additionally, the terms “a” and “an” as used herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. All publications mentioned herein are incorporated by reference for all purposes to the extent allowable by law.
The presently disclosed subject matter now will be described more fully hereinafter with reference to the accompanying drawings in which a specific embodiment is shown. However, it should be understood that this invention may take many different forms and thus it should not be construed as being limited to the specific embodiments set forth herein.
The invention encompasses a light bulb comprised of a plurality of LEDs having switch controlled illumination intensities.
In a broad embodiment, the invention encompasses a light bulb device comprising an AC electrical input, a plurality of (one or more) LEDs capable of emitting variable light intensities depending on the DC input current. The LEDs are in electrical communication with a driver board. The driver board is in communication with the AC electrical input. The driver board comprises a rectifier for rectifying AC current into DC current, and a switch having at least two selectable positions corresponding to a DC output of a first amperage or a second amperage corresponding to the selected switch position. The switch directs the current through one of two or more selectable resistors to provide the desired current, that is inversely proportional to resistance for a given voltage. The DC output amperage corresponds to the light output intensity of the LED(s).
The switch generally has one input pole (but could in other embodiments include a plurality of input poles), and generally has a plurality of output poles.
The switch (“the resistor switch”) switches the current between a plurality of resistors.
The switch can take the form of a slide switch, a push-button switch, a rotary switch, a pull switch, a toggle switch, a knife switch, a touch switch, or any other multiple position switch suitable for selecting current through a resistor.
In other embodiments another switch (a ‘capacitor switch’) is provided, upstream of the resistor switch, that switches the current between alternative capacitors. The capacitor switch can have a single input, and multiple outputs corresponding to a plurality of capacitors, for example, 1, 2, 3, 4, 5, 6, or 7 or more capacitors. Each capacitor will be associated with, and will conduct current to, a resistor switch, which will switch the current between a plurality of resistors, as previously described. In this way the range of DC current, and therefore luminescence, in increased.
In one embodiment, two switch positions correspond to a first amperage and a second amperage wherein both amperages are sufficient to cause at least one (or all) of the LEDs to emit light.
In another embodiment the switch comprises at least three selectable switch positions at least two of which correspond to an amperage sufficient to cause at least one LEDs to emit light, and wherein at least one selectable switch position corresponds to an “off” position wherein no said LEDs emit an appreciable intensity of light visible to the human eye in normal daylight conditions.
In certain embodiments the device of the invention includes a current regulating device. This current regulating device may, for example, be a chip (in the exemplary embodiment the inventors used an “lm ”) that pulse width modulates (PWM) the gate of the output MOSFET (metal-oxide-semiconductor field-effect transistor). The IC measures the voltage through the ISNS pin and regulates the current accordingly.
Although a MOSFET is used in the example, any transistor providing the same functions may be used in other embodiments (e.g., an FET, a BJT or even more crudely, anything that can produce a constant DC voltage, may be employed).
In one embodiment a second transistor is provided that in conjunction with the Zener diode provides constant voltage.
An exemplary embodiment provides a switchable luminance LED light bulb device comprising: an AC input component in functional communication with a driver board, the driver board comprising a rectifier, wherein the DC current is fed into a switch, the switch having a single input pole and multiple output poles and a plurality of selectable positions, wherein the switch directs the current through one of a plurality of selectable resistors corresponding to one of a plurality of different DC output currents, wherein the selected DC output current is fed into at least one of a plurality of light emitting diodes, wherein the selected DC output current corresponds to the light output of the light emitting diodes.
The switch may be of any suitable type such as a slide switch, a push-button switch, a rotary switch, a pull switch, a toggle switch, a knife switch or a touch switch.
In some embodiments any selectable DC output current is sufficient to cause at least one of a plurality of light emitting diodes to emit light. In other embodiments at least one selectable DC output current corresponds to an “off” position and is insufficient to cause at least one of a plurality of light emitting diodes to emit light.
The device may include a current-regulating device functionally associated with the driver board to regulate current to the LEDs. The current-regulating device may be a current regulating integrated circuit.
The device may include a current-regulating device and at least one transistor, wherein the current regulating device modulates the gate of the output transistor (for example, but not necessarily, a MOSFET or other field-effect transistor) by measuring the voltage, thereby regulating current.
In some embodiments the device comprises at least two transistors wherein one transistor is in communication with the Zener diode so as to provide constant voltage to the current regulating device.
Other components in various embodiments may include a noise suppression capacitor downstream of the AC input, and a bridge rectifier downstream of the AC input.
Other embodiments may include voltage regulation by use of a Zener diode. The regulated voltage can be applied to an N-channel power MOSFET and the drain of the MOSFET may be connected to a node while the source connects to the anode of a Schottky rectifier and wherein the cathode of the Schottky rectifier connects to a second, fixed voltage node connected to a filter capacitor, wherein the second node also connects to the input of a current regulator and to the common pole of a switch having a single input pole and a plurality of output poles corresponding to a plurality of resistors, wherein the current regulator is a constant current controller that provides a regulated current for illuminating a light emitting diode.
Alternative commercial embodiments include a driver board is mechanically attached to a cap adapted to be releasably fitted to an AC electrical output socket. The cap may be of any suitable type such as an Edison-style screw cap or bayonet-mount cap or any other type of cap.
In some embodiments the switch includes an actuator that is manually operable, i.e. an external switch is provided by which means an operator can switch between intensities of illumination. The switch may alternatively be operable remotely, either by wire or wireless means of control.
In an exemplary embodiment the device includes an AC input component that routes the input voltage across a noise suppression capacitor to a bridge rectifier, wherein one output of the bridge rectifier goes to ground while the positive output goes to a node wherein the voltage at the node is applied to a Zener diode via a resistor to produce a regulated voltage on the gate of an N-channel power MOSFET, wherein the drain of the MOSFET connects to the node while the source connects to the anode of a Schottky rectifier, wherein the cathode of the Schottky rectifier to a second, fixed voltage node connected to a filter capacitor, wherein the second also connects to the input of a current regulator and a switch having a single input pole and a plurality of output poles corresponding to a plurality of resistors, wherein the current regulator is a constant current controller that provides a regulated current for illuminating a light emitting diode.
presents a schematic diagram of the electronics on the LED driver board 16. The AC line voltage is applied to input terminals which route the line voltage across a noise suppression capacitor and across the input terminals of a bridge rectifier . One output of the bridge rectifier goes to ground while the positive output goes to a node .
The voltage at the node is applied to a Zener diode via a resistor . This produces a regulated voltage on the gate of an N-channel power MOSFET transistor. The drain of the MOSFET connects to the node 18 while the source connects to the anode of a Schottky rectifier . The cathode of the Schottky rectifier goes to a node which connects to a filter capacitor . The node is therefore a fixed voltage node.
Note that when a “Schottky rectifier” is specified in this disclosure, any other rectifier performing the same function may be used, particularly any semiconductor diode with a low forward voltage drop and a very fast switching action.
The node also connects to the Vcc input of an LM current regulator IC and to the common terminal of the switch 32, which may be a single pole double throw (SPDT) switch. Note in , the switch referred to in parts of the text as part ‘32’ is actually labeled ‘SW1’. When reading ‘32’ please substitute ‘SW1. Thus the single input pole of the switch 32 controls which of its two output poles and is selected. The current regulator IC is a constant current controller that regulates current for powering one or more LEDs. The actual regulated current is controlled by the pole position of the switch 32. The voltage on the node is selectively switched by the switch 32 between resistors and via poles , , respectively. While the switch 32 in the example is only a double throw switch, in other embodiments more switching poles can be used with more capacitors and/or resistors to achieve additional switch selectable lumens.
Having two (or greater) switch selectable DC current magnitudes reflects a beneficial design choice characterized by both low cost and simple user operation. However, another useful embodiment uses a three position illumination control switch, two positions of which select DC current magnitudes while the third position turns the LED light bulb 10 OFF. Another useful embodiment also uses a three position illumination control switch, but all three positions select different DC current magnitudes, thus allowing the illumination control switch to select three different illuminations. Other useful embodiments have 4 to 10 and possibly even more illumination control switch positions that select different DC current magnitudes (including OFF) and thus the illumination control switch can select four to 10 or more different illuminations. All of those embodiments as well as others that fall within the broad scope of the appended claims are encompassed by this invention.
The principles of the present invention are illustrated in the exemplary embodiment shown in . Referring now to the present invention relates to an LED light bulb 10. The LED light bulb 10 includes an Edison-type screw cap 12 that mates with prior art Edison-type bases. In fact, the LED light bulb 10 is configured to be a direct replacement for prior art Edison light bulbs. Thus the LED light bulb 10 is directly useable in millions of existing applications.
Still referring to , the Edison screw cap 12 connects to a driver case 14 which houses an LED driver board 16. The driver case 14 connects at its other end to a heat sink 18 such that the devices on the LED driver board 16 are in thermal communication with the heat sink 18. In certain embodiments the light engine is in thermal communication with the heat sink, and in other embodiments the driver board may not be in thermal communication with the heat sink. Attached to the other end of the heat sink 18 is a light diffuser 20. The light diffuser 20 covers a light engine 26 board that is in thermal communication with the heat sink 18. An actuator arm 30 of a multiple position switch 32 on the LED driver board 16 pass through a slot 34 that extends along the driver case 14. Note in , the switch referred to in parts of the text as part ‘32’ is actually labeled ‘SW1’. When reading ‘32’ please substitute ‘SW1’.
presents another mechanical view of the LED light bulb 10. shows the diffuser 20 as being attached to the light engine 26 by clips 40. Note that clips are given as an example, but any suitable fixing device may be used such as screws, solder etc. Inside the light engine 40 is a printed circuit board PCB 42 that holds an array of white-LEDs 44. The white-LEDs 44 are arranged to emit white light into the diffuser 20. Also as shown the light engine 26 is attached to the heat sink 18 by screws 46. Note that screws are given as an example, but any suitable fixing device may be used such as clips, solder etc.
The heat sink 18 covers most of the driver casing 14. Located inside the driver casing 14 is the LED driver board 16. As shown the LED driver board 16 includes a bridge rectifier 52, a buck converter 54, the multiple position switch 32 and a driver IC 56, while the driver casing 14 is attached to the Edison screw cap 12 by glue 60. Note that any form of fixing agent may be used.
The white-LEDs 44 operate on direct current (DC) electrical current while the standard household current power is AC. Thus rectification is required. Furthermore, the LEDs 44 operate at relatively low voltages and for proper operation they receive regulated DC currents supplied at appropriate low voltages. The higher the DC current the more light (lumens) and heat the white-LEDs 44 produce. The LED light bulb 10 provides for two or more switch 32 selectable DC currents that are selectively applied to the white-LEDs 44 to emit light as well as for thermal heat sinks and cooling. While other configurations might include a switch that completely turns off the LEDs, in the LED light bulb 10 both switch 32 positions cause light to be emitted from the white-LEDs 44. Both the electrical operation and thermal paths are important. In the present example the LED light bulb 10 provides for two switch 32 selectable DC currents, however in other embodiments, 3, 4, 5 or more selectable DC currents may be provided by the switch.
The overall electrical path of the LED light bulb 10 is shown in . AC voltage is input to the LED light bulb 10 and is directed to the LED driver board 16. As previously described the LED driver board 16 includes the driver IC 56, the bridge rectifier 52, the buck converter 54, and the switch 32. The switch 32 has multiple poles that control the DC current that is applied to the light engine 26, its white-LEDs 44, and its printed circuit board PCB 42. The printed circuit board 42 retains the white-LEDs 44 while the amount of the applied DC current depends on which position of the switch is selected. Since the switch 32 controls the amount of DC current it also controls the light output of the white-LEDs 44.
The efficiency of white light LED devices is increasing over time. Thus, the number of individual white-LEDs 44 required in a particular application will depend both on the amount of light output desired as well as the efficiency of the individual LEDs 44. However, it should be understood that the LEDs 44 do not uniformly emit light, and that their lumen (light) outputs are directed into the diffuser 20 which diffuses the light in a more uniform way.
presents a schematic diagram of the electronics on the LED driver board 16. The AC line voltage is applied to input terminals which route the line voltage across a noise suppression capacitor and across the input terminals of a bridge rectifier . One output of the bridge rectifier goes to ground while the positive output goes to a node .
The voltage at the node is applied to a Zener diode via a resistor . This produces a regulated voltage on the gate of an N-channel power MOSFET transistor. The drain of the MOSFET connects to the node while the source connects to the anode of a Schottky rectifier . The cathode of the Schottky rectifier goes to a node which connects to a filter capacitor . The node is therefore a fixed voltage node.
The node also connects to the Vcc input of an LM current regulator IC and to the common terminal of the switch 32. Thus the single input pole of the switch 32 controls which of its two output poles is selected. The current regulator IC is a constant current controller that power the high power LEDs. The actual regulated current is controlled by the pole position of the switch 32. The voltage on the node is selectively switched by the switch 32 between resistors and via poles , , respectively. While the switch 32 is only a double throw switch, in other embodiments more switching poles can be used with more capacitors and/or resistors to achieve additional switch selectable lumens.
The outputs of the resistors and (and any other lumen control resistor that is used) are applied to the C-off input pin (pin 4 in the figure) input of the current regulator IC and to a high frequency filter capacitor . The current regulator IC regulates the voltage on a gate output which is applied via a resistor to the gate of an N-Channel MOSFET . The source of the N-Channel MOSFET connects to ground via a current sense resistor and to a current sense input of the current regulator IC . The drain of the N-Channel MOSFET connects to an Driver output terminal via a transient reducing inductor .
The LEDs 44 are series connected with the cathode end connecting to an Driver output terminal and the anode end connecting to an driver output terminal . A filtering capacitor also connects between the Driver output terminal and the Driver output terminal . Connected between the Driver output terminal and the drain of the N-Channel MOSFET is a fast recovery diode having its cathode end connected to the Driver output terminal . Connected between the Driver output terminal and the node is a Schottky diode having its cathode connected to the Driver output terminal .
The current-regulating device regulates the current applied to the LEDs. The current-regulating device in the example is specified as regulating about mA to about mA of DC current. In some alternative embodiments the device may draw between 10 mA and , mA, for example between and mA, or between and mA, or between and mA, or between and mA. The LED light bulb may be configured to have similar light outputs to incandescent bulb of 1 W, 5 W, 10 W, 25 W, 50 W, 75 W, W, W, W, W, W and 10, W or even more.
In operation, the bridge rectifier places a rectified voltage on the node . The current through the LEDs 44 passes through the N-Channel MOSFET , with that current being regulated by the voltage applied by the current regulator IC to the gate of the N-Channel MOSFET . That current is sensed by the current regulator IC by its monitoring of the voltage drop across the sensing resistor . The desired current depends on the current through either the resistor or , depending on which is selected by the pole position of the switch 32. Once the resistor , is selected the current regulator IC regulates the current through the LEDs 44.
The LEDs 44 in the LED light bulb 10 are connected as two series-parallel strands of LEDs. The leading cathode input end of each strand is connected to the Driver output terminal and the trailing anode output end of each strand is connected to the Driver output terminal .
Referring now to , the LEDs 44 generates heat. That heat is transferred to the PCB 42, which is composed of FR4 material with copper planes on top and bottom connected by electrically-isolated, thermally-conductive through-hole vias. From the PCB, heat is conducted to the heat sink 18 which radiates heat to the ambient air . In other embodiments, metal-core PCBs may be used to allow for heat transference.
Therefore, it is to be understood that while the figures and the above description illustrate the present invention, they are exemplary only. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. Others who are skilled in the applicable arts will recognize numerous modifications and adaptations of the illustrated embodiments that remain within the principles of the present invention. Therefore, the present invention is to be limited only by the appended claims.
Lumens to Watts – how to choose light bulbs, brightness, colour and lifespan
Compare Incandescent bulbs to LED, CFL & Halogens
|Select wattage: 40 W|
*lumens conversion based on averages of Energy Star LED/CFL testing data
‡based on hrs a day at the Average rate of p/kWh (December tariff) for a unit of electricity. Household cost based on 12 bulbs.
What Wattage is right?
In recent years choosing light bulbs has become far more confusing – you knew roughly what you were getting with a 40, 60 or wattage filament bulb. Nowadays, energy saving bulbs produce far more light, less heat, whilst consuming less energy (Watts). They come in varying technologies, such as Compact Fluorescent (CFL), Halogen and LED and they last much longer – up to 25 years for LEDs!
Defining the brightness, or light output of bulbs is changing from wattage equivalents to lumens. Lumens is an accurate way of measuring the light output of bulbs – brightness is what we perceive, luminance is what we measure. However, this can be a little confusing!
Most of us have a preconception of how bright a watt incandescent bulb is even though this can vary tremendously between soft white and clear glass bulbs. On average, an incandescent bulb produces around 14 lumens per watt, compared to 63 lumens for energy saving compact fluorescents (CFL) and 74 for LED bulbs. Some of the most energy to light efficient LED bulbs are now reaching over lumens in Energy Star tests.
Wattage to Brightness Comparison
A 40 watt incandescent filament bulb produces roughly lumens. An equivalent compact fluorescents (CFL) bulb in light output (lumens) should consume only around 7 watts and LEDs approximately 6 watts.
|Incandescent Bulb Wattage||Equivalent Halogen Bulb Wattage||Equivalent CFL Bulb Wattage||Equivalent LED Bulb Wattage|
|40 W (~ lm)||28 W||7 W||6 W|
|60 W (~ lm)||45 W||13 W||11 W|
|75 W (~ lm)||56 W||18 W||15 W|
|W (~ lm)||80 W||28 W||24 W|
Data sources: American Association of Physics Teachers and Energy Star
What else can affect brightness perception?
The colour of light can also affect how bright a light appears, even if the lumens are the same. Bulbs that are nearer to daylight (bluer or cooler in colour) sometimes appear brighter than yellower coloured lights.
Choosing the colour temperature of bulbs
Choosing the right colour is dependent on the atmosphere you’re trying to create within your room, or what the space you are lighting is used for.
Light colour is measured using a temperature scale called Kelvin (K). Incandescent bulbs are around K and produce a yellower warm/soft light, great for creating a relaxed ambiance. For whiter light – more akin to daylight – good for kitchens and workspaces, bulbs labelled between K would be best. Reading lights tend to be marked K these appear much bluer and perceived as brighter.
How long do bulbs last?
There are many factors that will affect the longevity of a bulb. These include the quality of the design/manufacturing, their usage, such as turning ‘on and off’ frequently and their positioning.
The heat generated by bulbs can also affect their longevity, even with LEDs which create very little heat when compared to incandescent bulbs. LEDs disperse heat by using heat sinks to transfer it away from the LED. Excessive temperatures can affect the light quantity and quality over time, or generate flicker. Fitting bulbs within an enclosed space with restrictive airflow may well shorten the life of any bulb.
|Select daily bulb usage:|
Source: Energy Star/Energy.gov
Thankfully LED lights last much longer than the old incandescent bulbs. And even after many hours of lighting, an LED lamp does not simply burn out. Instead, an LED ages with time and its luminosity slowly decreases. This effect is known as degradation or decrease in luminous flux. Here you can find out why LEDs get darker over time.
Do LED lamps get darker over time?
We have become used to a long lifespan of 50, hours and more with LED luminaires and light sources. The old incandescent and halogen lamps, on the other hand, broke down after just a few thousand hours. At the end of the life expectancy the filament breaks and the lamp remains dark. Such a sudden defect cannot occur with LEDs. Nevertheless, there are also signs of ageing here, which are called as follows:
- Loss of brightness
- Luminous flux decrease
After purchasing an LED lamp usually has the brightness specified by the manufacturer. Over time, the luminosity slowly decreases and the lamp becomes darker. By the way, this effect also occurs with old incandescent and halogen lamps and especially with energy-saving lamps.
The decrease in LED luminosity is not linear. The luminous flux decreases very slowly in the beginning and decreases faster and faster with time. However, this is an extremely slow process over the entire lifespan. The decrease in luminous flux will therefore not be noticed in practice.
Why do LEDs lose their luminosity?
An LED lamp consists of several components. These include a small power supply, an LED driver and the LEDs themselves. The loss of brightness is mainly due to the structure of the light emitting diode. Minimal impurities in the semiconductor crystal of the LED chip cause material changes over time.
This process progresses slowly due to the heating of the LED each time it is switched on and during the lighting time. An increased ambient temperature or a mounting position with insufficient cooling accelerates the process. The technical term for this aging process is degradation.
What means LED degradation?
The term degradation in connection with LED lighting describes the decrease in luminous flux over the course of a lifetime. The luminous flux slowly decreases due to material changes in the LED chip and clouding of the optics. Degradation is therefore an ageing process in which an LED lamp loses its brightness over time and slowly becomes darker.
How is degradation measured?
In order to determine the percentage decrease in luminous flux of an LED illuminant, the luminous flux must be measured both when new and at the end of the specified lifespan. A comparison of both values shows the difference and provides information about the degradation.
The luminous flux of a light source can be measured using an integrating sphere and a photometer. However, the long life of an LED lamp poses a problem for a real measurement. One would have to wait many years until the real aging of the lamp occurs. For this reason, LED lamps are artificially aged so that more reliable results on the decrease in luminous flux can be obtained more quickly.
Is the degradation indicated?
The nominal lifespan must be specified by the LED manufacturers on the packaging. This does not apply to degradation. However, more and more manufacturers are now stating the reduction in luminous flux on the packaging or in the data sheet. There you will find additional information such as L70 or L
With a stated lifespan of 30, hours, for example, L70 means a 30% reduction in luminous flux. With L80, the luminosity is only reduced by 20%.
What does this decrease mean in practice?
For many consumers, the drop in luminous flux of LED luminaires and light sources is unknown. Most people suspect that an LED lamp will fail abruptly after the specified life expectancy, similar to its predecessors. Of course, a sudden defect cannot be ruled out with LEDs either. The cause is usually a fault in the electronics. This has nothing to do with LED degradation.
Since the aging process takes place extremely slowly over many thousands of hours, one will not notice the decrease in luminous flux in practice. Even a loss of brightness of 30% would not be noticeable. The difference would only be noticeable if an aged and a new identical LED light source were directly compared.
Now you know the decrease in luminous flux of LED lamps known as degradation. LEDs slowly lose their brightness during the time they light up. The usual loss of luminosity of 30% sounds dramatic at first. Even if the lamp actually gets darker over time, you will hardly notice the process in practice. A gradual loss of brightness is always better than a sudden failure.
Led light bulbs luminance
In the days of incandescent light bulbs , you could determine the bulb's brightness by the number of watts printed on the package. With today's LED bulbs, brightness is measured in lumens.
But, what the heck is a lumen? How is it different than a watt? How can you tell which LED bulb you need for your lamps and lighting fixtures?
Luckily, it's simple enough to sort out any confusion.
What the watt?
When buying an incandescent bulb, the watts rating gives consumers a good indication of how bright a bulb is. The more watts, the brighter the bulb.
That rule doesn't apply to LED bulbs, though. An LED that uses 60 watts is in no way comparable to an incandescent bulb that uses 60 watts. In fact, a watt LED just may blind you. LEDs are designed to use less energy and naturally have a lower watt rating. This means it's useless to use watts to determine brightness.
To fix the problem, bulb companies have started using lumens to rate bulbs. This gives you a more accurate indication of how much light to expect from an LED.
Measuring in lumens isn't a new concept designed just for LEDs. It's a rating that's been used for decades as a measurement of how much light a bulb (or anything else) emits. It just hasn't been predominantly displayed on packaging until recently. In , the US Federal Trade Commission started requiring manufacturers of compact fluorescent, incandescent and LED bulbs to use lumens as an indication of how bright a bulb will be.
"While watt measurements are familiar to consumers and have been featured on the front of light bulb packages for decades, watts are a measurement of energy use, not brightness," the FTC said in a press release. "As a result, reliance on watt measurements alone make it difficult for consumers to compare traditional incandescent bulbs to more efficient bulbs, such as compact fluorescents."
On packaging, the lumen rating is indicated by a number followed by "lm," the abbreviation for lumens. The higher the lumen rating, the brighter the bulb will be.
Picking the right bulb
The easiest way to figure out what bulb you need is by using an incandescent/LED conversion cart.
Say you normally use a watt incandescent bulb, for example. You would probably want to choose an LED bulb that uses 8 to 12 watts and has a lumen rating of to get the same illumination. This conversion chart will help you find an LED bulb similar to the incandescent you've been using:
As you can see, with LEDs, the amount of wattage you'll need varies for each lumen rating. This is because some LED brands have created bulbs that offer more lumens for less wattage. For the best energy savings, Energy Star recommends that you find a selection of bulbs with the most lumens you need, and then choose one with the lowest wattage.
Editors' note:This article was originally published on December 2, , and has been updated.
Need more help picking out the perfect lights for your home? Check out our list of the Best LED Light Bulbs of
Here's 5 reasons why your next light bulb should be a smart bulb.
Switchable Luminance LED Light Bulb
Tech ID: / UC Case
An alternative to incandescent lights are LEDs, which produce light through electroluminescence. This process creates very little heat and wastes little electricity, but otherwise relies on the same general principles of physics as incandescents. Incandescent lights use the electricity to heat up the filament inside the bulb and excites its electrons and thus, the process ultimately produces light, but most of the energy the light bulb consumes is wasted in the form of heat. However, unlike incandescent light bulbs, LED light bulbs include electronics to regulate light output and heat dissipation. LEDs can therefore be smaller, create the same amount of light using less electricity, and are safer because they wont cause burns, last longer, and are more durable. These advantages also make LEDs less expensive to produce and install.
UC Santa Cruz researchers have designed a low-power, transformer-less LED light bulb power supply. This invention is highly effective in providing levels of electric current enabling the LEDs to produce proportionally higher levels of lighting. The UCSC invention allows any lamp using the standard Edison screw or bayonet base (common with all incandescent bulb designs) to become an arbitrary-way lamp. This is similar to the commonly available 3-way lamp; however, it doesnt require a specialty lamp nor specialty 3-way bulb. It also allows for a bulb to have discrete light output, like a standard dimmable bulb. The current prototype can produce equivalent light to a 40W or 60W incandescent bulb, simply by setting the desired lighting level on the bulb at installation. Commercially the invention allows the manufacturer to produce one design in mass quantity that will fit many needs. Due to the low power (<10W) property of the LED light bulb, this invention is an appropriate replacement for almost all standard bulbs and holds consumer incentive to switch to an affordable equivalent LED light bulb.
- Significant increased functionally of the LED light bulb
Intellectual Property Information
|United States Of America||Issued Patent||9,,||08/08/|
|United States Of America||Issued Patent||9,,||09/22/|
LED light bulb, lighting, transformer-less, electric current, 3-way bulb, incandescent, eco-friendly, affordable, light bulb, Cat4
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