Patent Grant
9210760
The present subject matter relates to lamps for general lighting applications that utilize solid state light emitting sources and in particular to a solid state lamp for a three-way luminaire. The present subject matter also concerns apparatus and methods for disabling a solid state lamp at the end of its useful lifetime.
It has been recognized that incandescent lamps are a relatively inefficient light source. However, after more than a century of development and usage, they are cheap. Also, the public is quite familiar with the form factors and light output characteristics of such lamps. Fluorescent lamps have long been a more efficient alternative to incandescent lamps. For many years, fluorescent lamps were most commonly used in commercial settings. However, recently, compact fluorescent lamps have been developed as replacements for incandescent lamps. While more efficient than incandescent lamps, compact fluorescent lamps also have some drawbacks. For example, compact fluorescent lamps utilize mercury vapor and represent an environmental hazard if broken or at time of disposal. Cheaper versions of compact fluorescent lamps also do not provide as desirable a color characteristic of light output as traditional incandescent lamps and often differ extensively from traditional lamp form factors.
Recent years have seen a rapid expansion in the performance of solid state light emitting sources such as light emitting devices (LEDs). With improved performance, there has been an attendant expansion in the variety of applications for such devices. For example, rapid improvements in semiconductors and related manufacturing technologies are driving a trend in the lighting industry toward the use of light emitting diodes (LEDs), organic light emitting diodes (OLEDs) or other solid state light sources in lamps for general lighting applications. These lamps meet the need for more efficient lighting technologies and address ever increasing costs of energy along with concerns about global warming due to consumption of fossil fuels to generate energy. LED solutions also are more environmentally friendly than competing technologies, such as compact fluorescent lamps, for replacements for traditional incandescent lamps. Hence, there are now a variety of products on the market and a wide range of published proposals for various types of lamps using solid state light emitting sources, as lamp replacement alternatives.
Incandescent lamps are manufactured in many form factors and electrical configurations. For example, the base of an incandescent lamp may be configured as a one-way lamp or a three way lamp.
At a high level, a lamp 30, includes solid state light emitters 32, a bulb 31, an industry standard base 35 and a housing 33. The housing 33 extends into an interior of the bulb 31 and supports the bulb, the solid state light emitters 32 and a circuit board including electronic components of the lamp. In the examples, the orientations of the solid state light emitters 32 produce emissions through the bulb 31 that approximate light source emissions from a filament of an incandescent lamp. The illustrated example also uses an optional inner optical processing member 34, of a material that is at least partially light transmissive. The member 34 is positioned radially and longitudinally around the solid state light emitters 32 supported on the housing 33 and between an inner surface of the bulb 31 and the solid state light emitters 32. The bulb and/or the inner member may be transparent or diffusely transmissive. If provided, phosphors may be deployed on the inner optical processing member 34 or on the bulb 31. Lamp 30 also includes heat sink fins 36 which dissipate heat from the solid state light emitters 32.
Another attribute of incandescent lamps is their lifetime. At the end of its life, an incandescent lamp typically “burns out” when its filament breaks. A solid-state lamp, however, typically does not fail abruptly but exhibits increasingly degraded performance as it ages.
To be accepted by the public, it is desirable that LED lamps to conform to the form factors, electrical configurations and/or the end of life performance of incandescent lamps.
The teachings herein provide further improvements over existing lamp technologies. A three-way lamp example is configured to produce light from different sets of light emitters, one for each of the three electrical connections made by the luminaire. In another example, a lamp is configured to operate as a one-way lamp even when inserted in a three-way socket. In yet another example, a lamp is monitored for indications that it is approaching the end of its useful life and, when one or more of these indications crosses a threshold, the lamp is disabled, simulating an abrupt failure.
In the first example, a three-way lamp includes a power source, a controller, an output stage, switching logic circuitry and at least one set of light emitters. The logic circuitry is coupled to the power source to receive signals from the tip and ring contacts. The controller is coupled to provide power from the power source to the output stage and the output stage is coupled to the switch logic circuitry to selectively apply power to the light emitters responsive to the signals from the tip and ring contacts.
According to one aspect of this example, the at least one set of light emitters includes three sets of light emitters that are configured to emit light having respectively different color temperatures and the logic circuitry is configured to activate respectively different ones of the three sets of light emitters for each of three active states of the signals provided by the tip and ring contacts.
According to another aspect of this first example, the three sets of light emitters each has a respectively different number of light emitters.
According to yet another aspect of this first example, at least one of the three sets of light emitters is configured to produce light in a different color than the other two sets of light emitters.
According to still another aspect of this example, the at least one set of light emitters includes a single set of light emitters and the logic circuitry is configured to cause the controller to apply power to the light emitters responsive to a signal on the ring contact and on the tip and ring contacts and not to apply power to the light emitters responsive to a signal only on the tip contact so that the single set of light emitters cycles on and off responsive to changing switch positions of a three-way switch.
According to another example, a lamp includes a power source, a controller, an output stage, at least one set of light emitters and status monitoring circuitry, coupled to the controller, that monitors the status of the light emitters. The controller is coupled to provide power from the power source to the output stage and is coupled to the status monitoring circuitry to apply power to the light emitters as long as the status monitoring circuitry determines that the light emitters are within their useful lifetime. The status monitoring circuitry provides a non-volatile signal enabling the controller. When the status monitoring circuitry determines that the light emitters are no longer within their useful lifetime, it switches the non-volatile signal to disable the controller.
According to one aspect of this example, the status monitoring circuitry measures an amount of time that the light emitters emit light and disables the controller when this amount of time exceeds a threshold value.
According to another aspect of this example, the status monitoring circuitry measures a lumen level of the light provided by the light emitters and disables the controller when the measured lumen level is less than a threshold value.
According to yet another aspect of this example, the status monitoring circuitry measures a temperature of the light emitters and disables the controller when the measured temperature is greater than a threshold value.
Additional advantages and novel features of the examples will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings or may be learned by production or operation of the examples. The objects and advantages of the present subject matter may be realized and attained by means of the methodologies, instrumentalities and combinations particularly pointed out in the appended claims.
The drawing figures depict one or more implementations in accord with the present concepts, by way of example only, not by way of limitations. In the figures, like reference numerals refer to the same or similar elements.
In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings.
The various examples disclosed herein relate to solid state lamp assemblies that mimic and extend the functionality of corresponding incandescent lamp assemblies. Each of the embodiments described below concerns the electronic components of the lamp assembly. In addition to the described electronic components, each lamp includes a bulb and a housing on which the bulb and the electronic components are mounted and a base, such as shown in
Reference now is made in detail to the examples illustrated in the accompanying drawings and discussed below.
The positive output terminals of the power supplies 314 and 316 are connected to each other as are the negative output terminals. The combined positive and negative output terminals of the power supplies are connected to a filter circuit 318. The combined positive terminals of the power supplies are connected to provide operational power to switch logic circuitry 320. The operational power signal provided by the filter 318 is applied to the controller stage 322, which converts the filtered DC power signal into a power signal having a voltage and current suitable for the LED sets. Controller stage 322 applies this power signal to the output stage 324. The output stage 324 includes driver circuits that provide the power signal to the three sets of light emitters: set A including LEDs 1-N of color A; set B including LEDs 1-N of color B and set C including LEDs 1-N of color C. The output stage includes an output select matrix 326 which switches among the three sets of light emitters under control of the switch logic circuitry 320.
Switch logic circuitry 320 is coupled to receive signal inputs from the tip and ring lines, via the fuses 310 and 312. The switch logic circuitry is also coupled to a source of reference potential (e.g. ground). The circuitry 320 converts the alternating current (AC) power signals provided by the tip and ring lines into logic signals that are applied to the output select matrix 326 of the output stage 324 to control which set of LEDs is activated. In one implementation, the switch logic may employ two opto-isolators that receive the respective AC signals provided by the tip and ring lines as input signals, and produce output signals suitable for driving digital logic circuits in the output select matrix 326. An example opto-isolator circuit is described with reference to FIG. 16 in U.S. Pat. No. 8,212,469 entitled LAMP USING SOLID STATE SOURCE AND DOPED SEMICONDUCTOR NANOPHOSPHOR which is incorporated herein by reference. Alternatively, electromechanical relays may be used in place of the opto-isolators in the switch logic. Other applications describing the operation of lamps having solid-state light emitters include U.S. pub. nos. 2011/0176291, 2011/0176316 and 2011/0175528, which are incorporated herein by reference
Table 1 is a truth table showing the logic signals 327 and 328 produced by the switch logic responsive to the tip and ring signals and the resulting light emitter set selected by the output select matrix 326.
The logic signals output by the switch logic circuitry are described as logic-high (H) and logic-low (L). These designations do not indicate signal levels. For example, if the output select matrix uses negative logic, the voltage value of the H signal may be less than that of the L signal. The output select matrix 326 may be an analog 1 by 4 multiplexer. The operational power signal generated by the output stage 324 may be switched among the sets of LEDs as shown in Table 1.
In one implementation, the three sets of LEDs are of any type rated to emit energy of wavelengths from the blue/green region around 460 nm down into the UV range below 380 nm. In an example lamp, the light emitted by the LEDs is converted into white light by nanophosphors that have absorption spectra with upper limits around 430 nm, although other doped semiconductor nanophosphors may have somewhat higher limits on the wavelength absorption spectra and therefore may be used with LEDs or other solid state devices rated for emitting wavelengths as high as say 460 nm. In the specific examples, particularly those for white light lamp applications, the LEDs are near UV LEDs rated for emission somewhere in the 380-420 nm range, although UV LEDs could be used alone or in combination with near UV LEDs even with the exemplary nanophosphors. A specific example of a near UV LED, used in several of the specific white lamp examples, is rated for 405 nm emission.
The structure of a LED includes a semiconductor light emitting diode chip, within a package or enclosure. A transparent cover (typically formed of glass, plastic or the like), of the package that encloses the chip, allows for emission of the electromagnetic energy in the desired direction. In this implementation, the transparent cover also encloses semiconductor nanophosphors that convert the near UV light emitted by the LEDs into white light.
One or more doped semiconductor nanophosphors are used in the LEDs to convert energy from the source into visible light of one or more wavelengths to produce a desired characteristic of the visible light output of the lamp. In one example, the nanophosphors are selected such that the LEDs in set A produce white light with a color temperature of 2700K, the LEDs in set B set produce white light with a color temperature of 3500K and the LEDs in set C set produce white light with a color temperature of 5000K. The nanophosphors used to produce light in different color temperatures are a blend of single wavelength nanophosphors that produce white light having the desired color temperature.
The nanophosphor materials may be a solid, although liquid or gaseous materials may help to improve the florescent emissions by the nanophosphors in the material. For example, alcohol, oils (synthetic, vegetable, silicon or other oils) or other liquid media may be used. A silicone material, however, may be cured to form a hardened material, at least along the exterior (to possibly serve as an integral container), or to form a solid throughout the intended volume. If hardened silicone is used, however, a glass container still may be used to provide an oxygen barrier to reduce nanophosphor degradation due to exposure to oxygen. If a gas is used, the gaseous material, for example, may be hydrogen gas, any of the inert gases, and possibly some hydrocarbon based gases. Combinations of one or more such types of gases might be used.
While the example implementation uses LEDs providing white light at three different color temperatures, it is contemplated that LEDs providing light of a single color may be used for one or more of the light emitter sets. For example, the three-way lamp may provide a red light, to act as a night-light, if only the ring line is active and provide white light having a first different color temperature when only the tip line is active and having a second color temperature when both the tip and ring lines are active. In this instance, the nanophosphors in the LEDs in set A are selected to emit red light and the nanophosphors in the LEDs in sets B and C are selected to emit white light at the respective color temperatures.
For some lighting applications where a single color is desirable rather than white, the lamp might use a single type of nanophosphor in the material. For a red lamp type application the one nanophosphor would be of a type that produces predominantly red light emission in response to pumping energy from the LEDs. The upper limits of the absorption spectra of the exemplary nanophosphors are all at or around 430 nm, therefore, the LEDs used in such a monochromatic lamp would emit energy in a wavelength range of 430 nm and below.
Alternatively, conventional red LEDs may be used in place of the near UV LEDs and the red nanophosphors. If a red LED is used, however, it may be desirable to use one that produces a relatively bright light, for example a superluminescent LED (SLED). It is contemplated that the LED sets A, B and C, may all be single color sets using either near UV LEDs with a single color phosphor or single color LEDs or SLEDs.
The post 330 shown in
Alternatively, the post 340 shown in
The example lamp shown in
The lamp shown in
Table 2 describes the function implemented by the switch logic 410.
From this table, it may be seen that the logic function may be performed using an opto-isolator (not shown) to convert the ring signal to the Enable logic signal.
As previously described, it may be desirable for both one-way and three-way solid state lamps to include circuitry that disables the lamp when a condition is detected indicating that the lamp has reached the end of its useful life. An incandescent lamp provides an essentially constant same lumen output over its lifetime. The lumen output of solid state lamps gradually decreases over the lifetime of the lamp. This may be hazardous if a lamp is used in an environment requiring a predetermined minimum lumen level. Because the luminosity of the solid state lamps decreases gradually, a person using the lamp may not notice that it has been degraded. In addition, as solid state lamps age, they become less efficient, producing more heat as they produce less light. This may be undesirable in applications where the efficiency of the lamp is important, such as lighting systems run from battery power.
The example lamps described below with reference to
Both one-way and three-way lamps may benefit from lifetime monitoring. If the lamp 500 is a three-way lamp, there may be control signals generated by control logic (not shown) implemented in the input power stage 510. These optional control signals are shown by the dashed line from the input power stage 510 to the controller stage 514 and output stage 510 as described above with reference to
The controller stage 514 in the lamp 500 receives an Enable signal from sensor logic and conditioning circuitry 518. The circuitry 518 is coupled to a sensor 520. In one implementation, the sensor 520 includes a thermal sensor which is coupled to the LEDs 517. In another implementation, it includes an optical sensor that is configured to measure the light provided by the LEDs 517. In yet another implementation, the sensor 520 includes both optical and temperature sensors. In the example lamps shown in
As described in the above-referenced published patent application, solid state lamps typically include heat dissipation elements that prevent the solid state light emitters from being damaged by excessive heat. In addition, as described above, the solid state emitters may become less efficient as they age, generating more heat and less light. One implementation of a thermal sensor may thermally couple a temperature sensor, for example a thermocouple or thermistor, to one or more of the LEDs 517. This implementation may generate the signal disabling the controller 514 when the sensed temperature is greater than a threshold value. This type of sensor may also be useful for preventing the LEDs from being damaged in normal operation when the lamp is used in an environment when the heat dissipation elements are not effective at removing heat. In this usage, however, the disable signal may not be permanent but may re-enable the lamp when the measured temperature falls below the threshold value.
Because the lamp may be operated in environments having different heat profiles, absolute temperature may not be a good measure of lamp lifetime. One alternative may be to measure differential temperature, for example when the LEDs 517 are cycled between Off and On states. An LED at the beginning of its lifetime has a different temperature profile than an LED near the end of its lifetime. For example, as it approaches the end of its useful life, the LED may heat up quickly to a higher temperature. The sensor logic and conditioning circuitry 518 may include differentiating circuitry that measures the rate of increase of the temperature and disables the controller stage 514 when the measured rate exceeds a threshold.
In a three-way lamp, it may be desirable to include multiple thermal sensors 520, one for each set of LEDs. In this implementation, the Enable signal provided to the controller stage may be a two-bit signal indicating which set of LEDs should be disabled. The operation of this implementation would be similar to an incandescent three-way lamp in which one filament can fail but the lamp continues to provide light from another filament.
In an alternative implementation, the sensor 520 may be an optical sensor rather than a thermal sensor. The optical sensor may be positioned in the lamp to receive light from the LEDs 517. In one implementation, the lamp may include an extra LED that is not used for light generation but, instead, is coupled directly to the light sensor 520. In another implementation, the light sensor 520 may be positioned in the lamp to measure the light emitted by one or more of the LEDs in their normal operation.
In this implementation, the sensor logic and conditioning circuitry 518 may compare the measured light level to a threshold value and generate the EOL output signal to disable the controller stage 514 when the measured light level is less than the threshold value.
In yet another implementation, the lamp may include both thermal and optical sensors. In this implementation, the signals provided by the two sensors may be combined to determine whether the lamp has reached its end of life. This combination may include disabling the lamp if either sensor indicates an end of life condition or only if both sensors indicate the end of life condition.
The threshold values of the operational characteristic indicating an end of life condition may be empirically derived from test data for a statistically significant number of lamps. Alternatively, the temperature and luminosity thresholds may be based on manufacturer's specifications for the LEDs 517. Determination of the threshold values may also take into account changes in the sensors due to time and environmental conditions. Also, because there may be some variation in the sensed values from sensor to sensor, it may be desirable for the sensor logic and conditioning circuitry to initially calibrate the sensor or to take predictable sensor variation into account when comparing the sensor values to the threshold values.
The implementations shown in
The timer includes a non-volatile register that is reset when the lamp is manufactured and is incremented at a predetermine rate, for example, once per second or once per minute, while the lamp is turned on. This register may, for example, employ a sufficient number of flash memory cells to hold a Boolean value that is greater than the expected lifetime of the lamp. The circuitry 610 may also include control circuitry that writes new values into the flash memory cells. The circuitry 610 may be configured to use the flash memory cells as the timer register or to use a separate timer register that is loaded from the flash memory when the lamp is turned on and stored back into the flash memory when the lamp is turned off. The circuitry 610 may include a small capacitor to store sufficient power to complete the storage operation after the lamp has been turned off.
In this example, the circuitry 610 may also include logic that generates the EOL disable signal when the timer reaches a predetermined value. This logic may be a digital comparator that compares the timer value to an EOL time value or it may be logic circuitry, such as a multi-input AND gate, that generates the EOL disable signal when the value in the timer register is a predetermined EOL value. As in the embodiment shown in
The circuitry 610 determines when the LEDs are turned on responsive to a monitor input from the output stage 518. This value may be a voltage drop measured across the LEDs when they are active. The circuitry 610 may also determine when the LEDs are turned on based on output signals provided by control logic (not shown) internal to the input power stage 512. As described above with reference to
The predetermined time value(s) are generated based on empirical lifetime data collected from a statistically significant number of lamps.
In another example implementation, the circuitry 610 does not measure an amount of time that the LEDs have been turned on but the number of times that they have been cycled from an off state to an on state. To implement this function, the circuitry may be configured to generate a delayed pulse signal when the lamp is turned on. This signal may be generated, for example, using an RC ramp circuit and a threshold comparator. When the lamp is turned on, the counter is powered up in time to count the delayed pulse signal. The count value is stored in a non-volatile register which may include a number of flash memory cells sufficient to hole a count of off-on cycles greater than the expected lifetime of the LEDs. When this count value is greater than a predetermined maximum count value, the circuitry 610 generates an EOL disable signal to disable the lamp.
In the examples described above, with reference to
It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “includes,” “including,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.
Unless otherwise stated, any and all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.
While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that they may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all modifications and variations that fall within the true scope of the present concepts.
| Number | Name | Date | Kind |
|---|---|---|---|
| 8212469 | Rains, Jr. et al. | Jul 2012 | B2 |
| 20100225251 | Maruyama | Sep 2010 | A1 |
| 20100308739 | Shteynberg et al. | Dec 2010 | A1 |
| 20110175528 | Rains, Jr. et al. | Jul 2011 | A1 |
| 20110176291 | Sanders et al. | Jul 2011 | A1 |
| 20110176316 | Phipps et al. | Jul 2011 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20150054410 A1 | Feb 2015 | US |
