BACKGROUND

[0001] The subject matter of the present disclosure relates to lamps and lighting devices and, in particular, to circuits that reduce run-up time in lighting devices that incorporate compact fluorescent (CFL) lamps.

[0002] Incandescent light bulbs have been available for over 100 years. However, other light sources show promise as commercially viable alternatives to the incandescent light bulb. For example, high-efficiency light devices like compact fluorescent (CFL) lamps are attractive for use in lamps in part because of energy savings through high- efficiency light output.

[0003] Problems with CFL lamps, however, include the delay that occurs for the CFL lamp to generate light at full brightness. In some CFL lamps, and under certain conditions, this delay can amount to one minute or more, during which the lumen output slowly increases or "runs-up" to the desired lumen output.

BRIEF DESCRIPTION OF THE INVENTION

[0004] This disclosure describes, in one embodiment, a lighting device that comprises a light source and a ballast circuit coupled with the light source. The ballast circuit has a source capacitor in parallel with the light source. The lighting device also comprises a boost capacitor coupled in series with the source capacitor. The lighting device further comprises a switch coupled between the source capacitor and the boost capacitor. The switch has a first position that directs a signal to the light source through the boost capacitor.

[0005] This disclosure also describes, in one embodiment, a boost circuit for use with a ballast component of a compact fluorescent (CFL) lamp. The boost circuit comprises a boost capacitor, a switch coupled with the boost capacitor, a first Zener diode coupled with the switch, and a timing capacitor coupled in series with the first Zener diode. In one example, the capacitor has a capacitance that causes the capacitor to develop a voltage in response to an input power signal that reaches a breakdown voltage for the first Zener diode.

[0006] This disclosure further describes, in one embodiment, a circuit for energizing a light source on a lamp in response to an input power signal. The circuit comprises a source capacitor coupled in parallel with the light source and a boost capacitor coupled in series with the source capacitor. The circuit also comprises a switch having a conductor coupled between the source capacitor and the boost capacitor. In one example, the switch has a first position that couples the boost capacitor in series with the light source.

[0007] Other features and advantages of the disclosure will become apparent by reference to the following description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Reference is now made briefly to the accompanying drawings, in which:

[0009] FIG. 1 depicts a side view of an exemplary lamp with a light source and that incorporates circuitry that can reduce run-up time of the light source;

[0010] FIG. 2 depicts a block diagram of another exemplary lamp that incorporates circuitry that can reduce run-up time of a light source; and

[0011] FIG. 3 depicts a schematic wiring diagram for the topology of yet another exemplary lamp that incorporates circuitry that reduces run-up time of a light source.

[0012] Where applicable like reference characters designate identical or corresponding components and units throughout the several views, which are not to scale unless otherwise indicated. DETAILED DESCRIPTION OF THE INVENTION

[0013] FIG. 1 depicts a side view of an exemplary light device 100 of the present disclosure with improved start-up characteristics. The lighting device 100 includes a light source 102, e.g., a compact fluorescent (CFL) device. The light source 102 pictured in FIG. 1 is illustrative only, and in other embodiments, the lighting device 100 can utilize other types of light sources, e.g., a Decor type. These other light sources may have an outer envelope (e.g., a globe, an A-line, or a reflector shape) with different characteristics (e.g., variations in size, shape, color, etc.).

[0014] As set forth more below, embodiments of the lighting device 100 include improvements that reduce run-up time of the light source 102. These embodiments include circuitry that generates an output with operating parameters (e.g., current, voltage, etc.) that energize the light source 102. In one embodiment, the lighting device 100 includes a circuit that causes the output to exhibit operating parameters that facilitate ignition and warm-up of the light source 102 and, in one example, reduces the run-up time by 40 % or more as compared with conventional devices. As the light source 102 approaches full brightness, and in one example achieves maximum brightness, the circuit modifies the operating characteristics to maintain the lumen output, e.g., at full brightness.

[0015] The lighting device 100 has a base assembly 104 with a body 106 and a connector 108, both of which may house a variety of electrical elements and circuitry that drive and control the light source 102. Examples of the connector 108 are compatible with Edison-type lamp sockets found in U.S. residential and office premises as well as other types of sockets and connectors that conduct electricity to the components of the lighting device 100. These types of connectors outfit the lamp 100 to replace existing light-generating devices, e.g., incandescent light bulbs. For example, the lighting device 100 can substitute for any one of the variety of A-series (e.g., A-19) incandescent bulbs often used in lighting devices. [0016] Embodiments of the lighting device 100 may also include a housing that surrounds the light source 102. The housing may comprise glass, plastic, or other types of transparent, translucent, partially-transparent, or partially-translucent material. The housing may have reflective portions or incorporate a reflective element that directs light the light source 102 generates away from the lighting device 100.

[0017] FIG. 2 illustrates a block diagram of another exemplary lighting device 200 of the present disclosure that has improved run-up performance over conventional devices. The lighting device 200 has a circuit 210 that generates an output with operating parameters (e.g., current, voltage, etc.) that energize the light source 202. The circuit 210 includes a ballast component 212 and a boost component 214. The ballast component 212 has a filter component 216, a converter component 218, and a drive component 220. In one example, the filter component 216 couples with an external switch 222. Actuation of the external switch 222 couples the circuit 210 with an input power signal from a power supply 224 (e.g., an alternating current (AC) supply). The external switch 222 can have a user interface (e.g., a slider control and/or rocker control) that causes the external switch 222 to conduct the input power signal to the lighting device 200.

[0018] The components of the circuit 210 manipulate the input power signal from the power supply 224 to generate the output to energize the light device 202. The filter component 216 can remove and/or minimize electromagnetic interference (EMI) and noise from the input power signal to generate a filtered power signal. The current converting component 218 converts the filter power signal to a converted power signal. Examples of the current converting component 216 include an AC/DC rectifier (or DC/AC inverter) that converts the filtered power signal, e.g., from alternating current (AC) to direct current (DC) and/or vice versa. The drive circuit 220 utilizes an arrangement of components to generate the output in response to the filter power signal with operating parameters that energize the light source 202. When in use with a CFL device, the drive circuit 220 will cause the output to exhibit operating parameters that can initiate an arc in the discharge tube of the CFL device and continue operation of the arc discharge thereafter.

[0019] The boost component 214 can modify the operating parameters (e.g., current, voltage, etc.) of the output to improve performance of the lighting device 200. For example, as a result of operation of the boost component 214, the output will exhibit a first operating parameter (e.g., a first current, a first voltage, etc.) and a second operating parameter (e.g., a second current, a second voltage, etc.) that is different from the first operating parameter. The output exhibits the first operating parameter during an initial ignition period, which defines a period of time that is required for the lumen output of the light source 202 to change from a first lumen output to a second lumen output. In one example, the first lumen output occurs when the light source 202 is not energized, i.e., the value of the first lumen output is zero. The second lumen output has a value that is less than the value of the first lumen output.

[0020] Examples of the ballast component 212 can embody all or part of a ballast circuit, which limits current flow, e.g., to fluorescent lamps. The ballast component 212 may incorporate all or part of the components shown in FIG. 2 and/or other components and combinations of components described herein. As discussed more below, the components of the circuit 210 can comprise various discrete electrical components (e.g., resistors, transistor, inductors, capacitors, etc.) that reside on a substrate, e.g., a printed circuit board (PCB), semiconductor, and/or suitable substrate. These components can be found on the same and/or different substrates depending, for example, on construction and packaging constraints. This disclosure provides a detailed topology for one example of the circuit 210 in FIG. 3.

[0021] FIG. 3 depicts a wiring schematic that shows topology for an exemplary lighting device 300. This topology includes various components (e.g., resistors, capacitors, switches, diodes, etc.) that are useful and can embody the design. This disclosure also contemplates other configurations of components that would form topologies other than that shown in the figures. [0022] As shown in FIG. 3, the circuit 310 includes a timing component 336 and a switching component 338 that includes a boost switch 340 and a boosting element (e.g., a boosting capacitor 342). The timing component 336 includes a plurality of timing resistors (e.g., a first timing resistor 344 and a second timing resistor 346), a plurality of timing diodes (e.g., a first timing diode 348 and a second timing diode 350), and a timing element (e.g., a timing capacitor 352). In one example, one or more of the timing diodes 348, 350 comprises a Zener diode to take advantage of the operating characteristics (e.g., breakdown voltage) of the Zener diode to facilitate operation of the boost switch 340, as discussed further below.

[0023] Exemplary combinations of components in the timing component 336 and the switching component 338 operate to change the operating parameter of the output power signal at the light source 302. During the initial ignition period, for example, the timing component 336 generates a first switching signal that maintains the boost switch 340 in a first position to cause the output to exhibit the first operating parameter. The timing component 336 can also generate a second switching signal that maintains the boost switch 340 in a second position. With the boost switch 340 in the second position, the output power signal exhibits the second operating parameter.

[0024] Referring again to FIG. 3, and moving now from left to right in the diagram, the circuit 310 forms a filter component (e.g., filter component 216 of FIG. 2) that comprises an LC circuit with a filtering capacitor 354 and a filtering inductor 356. Examples of the LC circuit filter noise from the input power signal and interference (e.g., electromagnetic interference) that the ballast circuit can induce in the input power signal. The circuit 310 also includes a converter component (e.g., converter component 218 of FIG. 2) that comprises an AC/DC rectifier, which incorporates a set of rectifier diodes 358. The AC/DC rectifier converts the input power signal to a DC signal. The circuit 310 further includes a buffering component in the form of a buffering capacitor 360, with parameters (e.g., capacitance) that are selected so that the buffering capacitor 360 will develop and maintain a certain voltage (or charge) in response to the DC signal. [0025] The circuit 310 also includes components for a drive circuit (e.g., drive circuit 220 of FIG. 2). The drive circuit generates the output with operating parameters to operate the light source 302 (e.g., a CFL device). In one example, the circuit 310 includes a start-up circuit, which has one or more start-up resistors (e.g., a first start-up resistor 362 and a second start-up resistor 364), a start-up diode 366, one or more start-up capacitors (e.g., a first start-up capacitor 368), and a diode for alternating current (DIAC) 370, which is a diode that conducts current only after reaching a breakdown voltage. The circuit 310 also includes an inverter with a snubber capacitor 372, one or more switches (e.g., a first inverter switch 374 and a second inverter switch 376), one or more inverter resistors 378, and one or more inverter inductors 380. In one embodiment, the circuit 310 also includes one or more resonant tank components (e.g., a resonant inductor 382, a first resonant capacitor 384, and a second resonant capacitor 386) and a source capacitor 388.

[0026] In one implementation, the AC/DC rectifier converts the voltage of the input power signal from AC voltage to DC voltage to charge the first start-up capacitor 368 by current through the first start-up resistor 362 and the second start-up resistor 364. The charge on the first start-up capacitor 368 triggers the DIAC 370, which in turn causes the first inverter switch 374 to conduct the input power signal through the remaining components of the circuit 310, thus forming the output power signal at the light source 302 to generate light. In one example, the input power signal conducts through the resonant tank formed by the resonant inductor 382, the first resonant capacitor 384, the second resonant capacitor 386, and the source capacitor 388. The boost switch 340, in its first position, places the source capacitor 388 in series with the boost capacitor 342 and in parallel with the second resonant capacitor 386. Coupling the boost capacitor 342 in series with the source capacitor 388 causes the output power signal at the light source 302 to exhibit the first operating parameter, which in one example comprises an first current level with a value that improves ignition performance. Examples of the first current level effectively depend on the capacitance of the boost capacitor 342. [0027] The input power signal also charges the timing capacitor 352 by current through the first timing resistor 344. In one example, when the charge across the timing capacitor 352 reaches the breakdown voltage of the first timing diode 348, the boost switch 340 changes from the first position to the second position. This change from the first position to the second position reduces the voltage across the boost capacitor 342. The reduction in voltage across the boost capacitor 342 causes the output at the light source 302 to exhibit the second operating parameter. In one example, the second operating parameters comprises a second current level with a value that is less than the value of the first current level. Moreover, the initial ignition period (i.e., the period of time that expires before the current level changes from the first current level to the second current level) may depend on values for one or more of the resistance of the first timing resistor 344 and/or the second timing resistor 346, the capacitance of the timing capacitor 352, and the breakdown voltage of the first timing diode 348.

[0028] In view of the foregoing, this disclosure describes various configurations of lighting devices (e.g., lighting devices 100, 200, 300 of FIGS. 1, 2, and 3) that offer improved performance over conventional devices. These configurations reduce the runup time that is required for the light source and, in one particular embodiment, a compact fluorescent device, to achieve desired lumen output in a shorter time period relative to conventional devices. In one embodiment, the lighting device utilizes circuitry that can regulate the current level of the input power signal that energizes the light source. At start-up, or initial ignition, the circuitry increases the current level to facilitate ignition of the light source and to achieve maximum brightness of the light source. The circuitry can then reduce the current level after a period of time to maintain the lumen output, e.g., at maximum brightness.

[0029] As used herein, an element or function recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or functions, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the claimed invention should not be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0030] This written description uses examples to disclose embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.