WO2000005930A1

WO2000005930A1 - Subcompact fluorescent lamp

Info

Publication number: WO2000005930A1
Application number: PCT/US1999/008720
Authority: WO
Inventors: Kamleshwar C. Gunsagar; Ishwar Dayal Jain
Original assignee: Planet Mirth
Priority date: 1998-07-23
Filing date: 1999-04-20
Publication date: 2000-02-03
Also published as: AU3658399A

Abstract

A subcompact fluorescent lamp is described. The subcompact fluorescent lamp needs no additional circuitry for power factor correction. The lamp includes a hollow reflector placed with the lamp module for improved reflectivity. The circuitry is partitioned to more effectively utilize the available space within the lamp module, resulting in a small overall size. Near unity power factor may be obtained through the use of an oscillator circuit which employs the intrinsic inter-electrode capacitances of two suitably biased transistors, one in common base configuration and the other in emitter follower configuration, to generate high frequency sinusoidal waveforms at the output of the collector of the transistor in the emitter follower configuration to drive the pulse transformer.

Description

SUBCOMPACT FLUORESCENT LAMP

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a subcompact fluorescent light bulb. More particularly, the present invention relates to a subcompact fluorescent light bulb which uses more compact circuits for total harmonic distortion power factor correction.

Description of Related Art

Incandescent light bulbs are inexpensive, readily available, and fit in almost all light fixtures. However, incandescent light bulbs use a lot of energy relative to the amount of light they produce.

Compact fluorescent lamps have been developed as a more energy-efficient alternative to incandescent light bulbs. They also outlast incandescent light bulbs.

However, compact fluorescent lamps cost significantly more than incandescent light bulbs, in part due to the electronics required to reduce the total harmonic distortion generated by fluorescent lamps. Moreover, currently available compact fluorescent lamps have poor power factor and are generally too large to fit into light fixtures which were originally designed to accommodate incandescent light bulbs.

What is needed is a subcompact fluorescent lamp which can fit light fixtures originally designed to accommodate incandescent light bulbs. What is also needed is a subcompact fluorescent lamp which is simpler and more cost-effective than currently available compact fluorescent lamps.

SUMMARY OF THE INVENTION The present invention is directed towards a subcompact fluorescent lamp. The subcompact fluorescent lamp includes a base having a neck and a body, the base having a diameter no greater than 58 mm, the neck capable of being coupled to a lamp fixture, an electronic ballast at least partially positioned within the body; and at least one U-shaped fluorescent bulb coupled to the base, wherein the overall length of the subcompact fluorescent bulb is no greater than 112 mm.

RRTEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A shows a perspective view of one embodiment of a subcompact fluorescent lamp of the present invention.

FIG. IB shows a perspective assembly view of the subcompact fluorescent lamp. FIG. 1C shows a perspective view of the subcompact fluorescent lamp without the cage.

FIG. ID shows another embodiment of the cage for the subcompact fluorescent lamp.

FIG. 2A shows a side assembly view of the subcompact fluorescent lamp. FIG. 2B shows a top view of the cage of the subcompact fluorescent lamp.

FIG. 2C shows a side view of the cage of the subcompact fluorescent lamp. FIG. 2D shows a top view of the fluorescent tubes of the subcompact fluorescent lamp.

FIG. 2E shows a side view of the fluorescent tubes of the subcompact fluorescent lamp.

FIG. 3 A shows a block diagram of one embodiment of an electronic ballast suitable for use with the subcompact fluorescent lamp of the present invention.

FIG. 3B shows a circuit diagram for a rectifier bridge for the electronic ballast. FIG. 3C shows a circuit diagram of one embodiment of a circuit used for almost unity power factor for the electronic ballast.

FIG. 3D shows a circuit diagram of an electronic ballast suitable for use with the subcompact fluorescent lamp of the present invention.

FIG. 3E shows a circuit diagram of another embodiment of an electronic ballast suitable for use with the subcompact fluorescent lamp of the present invention. FIGS. 4A-4B shows side and top views of another embodiment of a subcompact fluorescent lamp of the present invention. FIGS. 5A-5B show perspective and exploded views of yet another embodiment of a subcompact fluorescent lamp of the present invention.

DETAILED DESCRIPTION OF THE INVENTION This invention relates to the development of a low cost, unity power factor, subcompact fluorescent lamp, a practical replacement to the incandescent lamp, which has been around for over a hundred years. The objective of this invention is a subcompact fluorescent lamp which uses fluorescent tubes, and which is the same size and fits in the same fixtures as normal incandescent light bulbs. Fluorescent tubes, by the inherent nature of the ballast, which used to be mechanical ballasts before but now increasingly electronic ballasts, produced a lot of harmonic distortion, and also have a power factor issue. This is one reason why utility companies have not been pushing them hard. They are frequently referred to as energy saving devices, but the energy saving is only in the mind of the consumer. The utility companies are really not saving any money. They have to put in a lot more additional power capacity, in terms of the volt-amps required and in terms of the wattage required, to make the lamp cost-effective.

The subcompact fluorescent lamp of the present invention seeks to make the fluorescent tube lamp look like an incandescent lamp to the utility company. This subcompact fluorescent lamp invention is massively deployable. That means, without any cost to the utility companies, it can replace current incandescent bulbs anywhere in the world. The life of this bulb may be as high as 10 years, almost 10 times that of an incandescent bulb, thus offering significant cost savings.

Referring now to the drawings, FIGURE 1 A shows a perspective view of one embodiment of a subcompact fluorescent lamp 100 of the present invention. FIGURE

IB shows a perspective assembly view of subcompact fluorescent lamp 100. Subcompact fluorescent lamp 100 includes a base 110, a reflector 120, a cage 130, fluorescent tubes 140, and a ballast 150. Base cap 110 may include a screw or bi-pin type base, and may contain all or part of the electronics for ballast 150. Reflector 120 goes between fluorescent tubes 140. Reflector 120 has a shiny surface, such as a sputtered aluminum coating on it, which acts like a metal surface to increase the luminescence of subcompact fluorescent lamp 100. Reflector 120 is hollow, thus providing additional space to contain components of ballast 150. Reflector 120 may a slightly concave surface, so that more light can be reflected out.

Cage 130 protects fluorescent tubes 140 during transport and handling, and may be made of polycarbonate material or any clear glass material, being very light weight and having excellent transmission characteristics. Cage 130 also serves the purpose of providing mechanical strength so that when subcompact fluorescent lamp 100 is installed in a socket, the twisting motion does not damage fluorescent tubes 140, which may be very fragile. Currently available compact fluorescent lamps simply have exposed fluorescent tubes coming out of a base, so care must be taken when putting the lamp in a socket. Cage 130 also minimizes any damage to fluorescent tubes 140 if subcompact fluorescent lamp 100 is subjected to any impact. Cage 130 may include several openings lined up with reflector 120 to permit greater light output and improving heat dissipation through better air circulation. Cage 130 may also include small openings in the top also to accommodate varying tube lengths due to manufacturing tolerances. Cage 130 may also include a structure on the inside near the top to support the far end of reflector 120.

Fluorescent tubes 140 may be three or four U-tubes formed by conventional hot kissing techniques. The number of fluorescent tubes 140 used varies with the wattage required. Fluorescent tubes 140 of 60 lumens per watt may be used. Fluorescent tubes 140 may be three inches or less in length. Subcompact fluorescent lamp 100 has been designed so that all of ballast 150 electronics can fit within base 110 and reflector 120. FIGURE 1C shows a perspective view of subcompact fluorescent lamp 100 without cage 130. FIGURE ID shows another embodiment of cage 130 for subcompact fluorescent lamp 100. FIGURE 2 A shows a side assembly view of subcompact fluorescent lamp 100.

FIGURE 2B shows a top view of cage 130 of subcompact fluorescent lamp 100. FIGURE 2C shows a side view of cage 130 of subcompact fluorescent lamp 100. FIGURE 2D shows a top view of fluorescent tubes 140 of subcompact fluorescent lamp 100. FIGURE 2E shows a side view of fluorescent tubes 140 of subcompact fluorescent lamp 100.

FIGURE 3 A shows a block diagram of the electronic ballast. Electronic ballast includes a rectifier bridge 310 and an oscillator 320. Power from a power supply goes through a rectifier bridge 310, which takes AC voltage input and produces a floating DC voltage output. Rectifier bridge 310 may be a standard four diode bridge. FIGURE 3B shows a circuit diagram for rectifier bridge 310. Rectifier bridge 310 may include additional chokes LI, L2, L3, and L4, to it, to limit the inrush current. With this approach the inrush current is less than 3 A and at the same time control electromagnetic interference and radiofrequency interference to within prescribed limits. Normal fluorescent tubes take 5 or 10 A of inrush current, so this designs creates much less of a problem with the utility companies. The output voltage of rectifier bridge 310 is fed into a dual stage oscillator 320. FIGURE 3C shows a circuit diagram for oscillator 320 used for almost unity power factor. Oscillator 320 may be a dual stage oscillator which uses the inherent capacitance C8, which along with L5, R8, and R9 make oscillator 320 oscillate at a frequency high enough to make the waveform look very sinusoidal and almost unity power factor.

FIGURE 3D shows a circuit diagram for ballast 150 used in subcompact fluorescent lamp 100. The circuitry uses DIAC triggering of transistors into oscillation. The use of the intrinsic inter-electrode capacitance of the transistors eliminates the need for additional circuitry that would otherwise be needed to provide power factor correction. With appropriate choices of the biasing circuit components, the circuit can be made resistive for all frequencies when conditions for resonance have been met. In this particular application, these conditions exist when R8 = R9 = sqrt(L5/C8). Almost unity power factor is the result of this biasing circuit to the bases of the two NPN transistors, Ql and Q2, Ql being in the common base mode while Q2 is connected in the emitter follower mode. In a common base configuration, the output of Ql has no current gain and the wave shape is identical to the input wave shape. The input wave shape is generated by the oscillator circuit utilizing the base emitter capacitance as one of its components. The output of Ql is fed to the second oscillator stage which has Q2 connected in the emitter follower configuration. Output of Q2 has current gain and the output signal is in phase with the input. In this manner, both transistors are connected to operate in the active region, high frequency AC output is fed to the output transformer connected to the load. Ql and Q2 may be NPN bipolar transistors such as MJE 13005. R5, R6, R8, and R9 may be 20 ohms, 1/4 watt. DIAC may be a DB3. LI, L2, L3, and L4 may be choke coils, 1.8 - 3.8 mh, 10- 15 ohms. Transformer may be EE16 ferrite core with a suitable number of turns.

The use of this ballast design permits subcompact fluorescent lamp 100 to be constructed with a length of 4-7/16" or less, and a width of 2 1/2" or less. The use of these electronics means no additional circuitry is required for power factor correction.

Currently available compact fluorescent lamps typically use separate devices for total harmonic distortion and power factor correction. These devices are usually based on integrated circuits, which can be very expensive. Moreover, these devices are bulky and require considerable space. FIGURES 4 A and 4B show side and top views, respectively, of another embodiment of a subcompact fluorescent lamp 100 of the present invention. Subcompact fluorescent lamp 100 includes a base 110 and four U-shaped fluorescent tubes 140. Base 110 may include a neck 112 for coupling subcompact fluorescent lamp 100 to a light fixture and a body 114 to which the fluorescent tubes 140 are attached. Base 110 may also have one or more vent holes 116. Base 110 may have a diameter no greater than 58 mm.

FIGURES 5 A and 5B show perspective and exploded views of yet another embodiment of a subcompact fluorescent lamp 100 of the present invention. Ballast 150 may include a printed circuit board 152 and an inductor 154 which are housed completely within base 110. Ballast 150 may make use of a cylindrically shaped inductor 154 which is at least partially housed within the hollow of neck 112. Subcompact fluorescent lamp 100 may have an overall length no greater than 112 mm. Body 114 may be formed of one or more pieces to facilitate assembly of subcompact fluorescent lamp 100. Subcompact fluorescent lamp 100 may have a lifetime of more than 6000 hours, a light output of more than 900 lumen, a color temperature of 2700 K, a color rendering index of more than 82, and/or a working ambience of -20 °C to 50 °C.

The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in this art.

What is claimed is:

Claims

CLAIMS 1. A subcompact fluorescent lamp, comprising: a base having a neck and a body, the base having a diameter no greater than 58 mm, the neck capable of being coupled to a lamp fixture; an electronic ballast at least partially positioned within the body; and at least one U-shaped fluorescent bulb coupled to the base; wherein the overall length of the subcompact fluorescent lamp is no greater than 112 mm.

2. The subcompact fluorescent lamp of claim 1 , wherein the electronic ballast includes an cylindrically shaped inductor at least partially positioned within the neck of the base.

3. The subcompact fluorescent lamp of claim 1 , wherein the electronic ballast has a power factor of at least 0.6.

4. The subcompact fluorescent lamp of claim 1 , wherein the base is made of plastic.

5. The subcompact fluorescent lamp of claim 1 , wherein the fluorescent bulbs are coupled using hot kissing techniques.

6. The subcompact fluorescent lamp of claim 1, further comprising: a cage coupled to the base and at least partially surrounding the fluorescent bulbs.

7. The subcompact fluorescent lamp of claim 1, further comprisinng: a reflector coupled to the base and positioned adjacent to the fluorescent bulbs.

8. A subcompact fluorescent lamp, comprising: a base housing having a top and a bottom; a neck coupled to the bottom of the base housing, the neck configured to be inserted into a light bulb socket, the neck having a hollow; a plurality U-shaped fluorescent bulbs coupled to the top of the base housing; and an electronic ballast contained within the base housing, the electronic ballast including a cylindrically shaped inductor at least partially positioned within the hollow of the neck, the electronic ballast being connected to the neck and at least one of the fluorescent bulbs wherein the subcompact fluorescent bulb has a lumen output no less than that of a standard 60-watt incandescent light bulb and an overall length no greater than that of a standard 60-watt incandescent light bulb and a maximum diameter no greater than that of a standard 60-watt incandescent light bulb.

9. A subcompact fluorescent lamp, comprising: an electronic ballast; a plurality of fluorescent bulbs coupled to the electronic ballast; a standard light bulb neck coupled to the electronic ballast; and a lamp housing at least partially surrounding the electronic ballast and the fluorescent bulbs; wherein the total length of the neck and the lamp housing is no greater than 57 mm.