Patent Application
20090256482
The present invention relates to electrical lighting, and more particularly to incandescent light bulbs.
Many companies are in the process of attempting to develop technologies to reduce carbon emissions worldwide. Environmental side effects or manufacturing byproducts are being produced and many more have issues that are common drawbacks to their individual technologies. A good example and a technology that has gained notoriety over the last few years are the Compact Florescent Lights. The Compact Fluorescent Light has an efficacy of approximately 40-60 lumens per watt (lpw); and has been compared to its larger counterpart the larger four and eight foot tube fluorescents. However, the CFL has significantly lower light output as well as an increase in operating temperature, which translates to general temperature losses caused by the inefficient methods used to wrap the fluorescent tube into a smaller package. The smaller package actually blocks exiting light. Most of these compact fluorescent lights are in the 8 to 12 watt range and produce 400 to 600 lumens, and a common issue is that no two produce the same color temperature. In comparison, the typical household Incandescent bulb is 60 watts, producing 700 lumens.
What is needed is an improved incandescent bulb that reduces energy consumption, yet offers consistent and pleasurable color temperature yet does not use hazardous chemicals such as Mercury to pollute our landfills, while still have long useful life.
(TO BE COMPLETED BY ATTORNEY ON FINALIZATION OF CLAIMS)
These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein:
Like reference numbers and designations in the various drawings indicate like elements.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will become apparent from the description, the drawings, and the claims.
Lighting assemblies are typically measured for light output, color temperature, color rendering, efficacy and life. Color temperature is a measurement of how the eye perceives the color of the light. The Color Rendering Index (CRI) is a measure of the ability of a light source to reproduce the colors of various objects being lit by the source. Efficacy is measured as the amount of light given off per watt of power. Typically this is discussed in lumens/watt (lpw). Life is measured in hours of operation under normal environmental conditions.
Table 1 sets out a comparison of standard incandescent bulbs to the compact fluorescents bulbs. Table 1 shows why the compact fluorescent light (CFL) is superior to the typical 120 VAC filament based household incandescent bulb. The CFL's outperform the incandescent on efficacy, life and overall power usage. However, the incandescent is more pleasing to the human eye for color and overall appearance. This is due to the Color Rendering Index.
Incandescent bulbs produce a CRI of 100 where as CFL's are pushing to reach a CRI of 80. This in layman's terms means, the observed colors are true and have a richer feel, the line spectra from a CFL has been shown to promote headaches and eye fatigue in office and home settings.
The Halogen type of incandescent bulb is a improvement over the standard incandescent bulb due to several factors. Low voltage halogen incandescent bulbs utilize a smaller filament in a gas filled vessel. This allows the filament to burn brighter which improves efficacy, luminous output and life. This is due to less gas losses from the filament due to the smaller mass, and the simple fact that the low voltage filament is shorter and has a diameter several times the size of a 120 VAC filament. The larger diameter filament takes much longer to evaporate than the line voltage, smaller diameter filament.
The shorter single coil, low voltage filament also has better shock and support characteristics and makes a better point source for optical designs than longer filament bulbs.
Table 2 compares halogen bulbs to CFLs. As is shown in Table 2, the standard Halogen Incandescent still has dramatic improvements in efficacy, power used and life while having a pleasing color to the human eye.
Running the filament in a standard Halogen light at a lower voltage, with a shorter filament length and housed in an envelope with high fill gas such as halogen, delivers dramatic improvements as shown in the comparisons between Table 1 and 2. As shown, it decreased power consumption substantially over the regular incandescent bulb, If the filament could be improved further, theoretically, this would improve efficacy, life and increase luminous output even further.
The halogen lamp achieves its higher efficacy over the standard incandescent lamp due to the high fill pressure inside; the halogen mix keeps the bulb wall clean throughout life. The filament is the emitter of the light so let's look closer at the design of the filament.
Typical filaments are constructed of tungsten wire. Tungsten generally has an emissivity of about 0.6 or 60% compared to a theoretical black body, a standard measurement technique used in the lighting industry to rate filament output. Although the brightness varies from one material to another, the color (strictly spectral distribution) of the glow is essentially universal for all materials, and depends only on the temperature. In the idealized case, this is known as ‘black body’ or ‘cavity’ radiation, and is described by the well known Planck's Radiation Law.
This 0.6 emissivity (compared to an ideal emissivity of 1)is due in large part to the surface of the tungsten wire. If we sliced through the tungsten wire we would have a cylinder of tungsten.
The amount of light given off of this cylinder per unit volume is proportional to the ratio of the cross sectional area to the circumference, which is equal to the surface area of the wire when we multiply circumference by the length. Increasing the circumference while maintaining the cross sectional area improves the filament by giving more emissive surface for the same cross sectional area.
The maximum permissible current which can pass through the wire is proportional to the cross sectional area of the wire, while the maximum permissible emissivity of the radiated light from the wire is proportional to the circumference, ignoring heat loses.
If we increase the circumference of the wire, increase the surface area of the wire proportionally. It is desirable to maximize the circumference of the wire in relationship to the cross sectional area of the wire, subject to certain limitations discussed below.
In one embodiment as shown on
The circumference of the wire is no longer equal to n×d, but the total distance measured around the wire, while maintaining contact with the surface of the wire. In one example, the measured circumference of a unit diameter grooved wire was about 1.67 times longer than a smooth unit diameter surfaced wire. We obtain an overall increase of light output of 37%. If we multiply 24 lpw×1.37 (% gain) we get 32.88 lpw. The 700-lumen 60-watt standard incandescent lamp would be replaced by a 22-watt halogen lamp, with a special drawn grooved filament wire. (723 lm/32.881 pw/95% efficiency).
The 95% efficiency calculation is generated by the efficiency of additional electronics, which steps down the 120 Vac to a lower more efficient filament operating voltage of approximately 14 VAC.
Table 3 makes the same comparison of the improved bulb to the CFL.
When we consider heat loses due to the internal gases, we find the filament design will need to be compensated to counteract this effect. This is accomplished by making the surface grooving (or other surface area increasing surface variations)of a size as will trap the greatest portion of the non-visible infrared light. The new design type of Tungsten filament wire will also have an inherent increase in operating temperature, which will increase efficacy. This is accomplished by the IR wavelengths becoming trapped within the formed longitudinal channels within the wire since the size of the grooves (or surface pitting size or surface particle size) is made so as to be approximately of the same wavelength (700 nm to about 1200 nm)thus making resonant chambers to trap the IR while allowing the shorter wavelength visible to pass. PLEASE CONFIRM THIS.
Two methods that have proven particularly effective to produce a filament wire to create the above-mentioned increase in surface are (1) acidic etching of the completed filament and (2) die finishing.
Etching involves the utilization of sulfuric or other acid under extreme heat (such as 800 degrees Celsius) in a vacuum vessel to create the etching process. This is accomplished by utilizing a standard tungsten filament wire placed in a specially designed glass tube and combined with the acid. The glass tube is then placed under vacuum and inserted into a high temperature furnace. After the heating process, the unit is then removed, cleaned and examined.
The die finishing method improves on the existing method of drawing tungsten wire. Currently tungsten wire is drawn with dies and graphite lubricants. The wire is commonly finished with a chemical or electro-polish, which removes the outer surface of the wire and makes it more uniform and smooth. With the addition of a finish die with grooving mechanisms, and finishing the wire with a wet/dry Hydrogen fire at 1600±200 degrees Celsius to finish and clean the wire, we obtain the desired increase in surface area with a uniform grooving.
In yet another embodiment, voltage conversion circuitry well known in the art may be added to the lamp to provide optimal low voltage power to the bulb. Power may also be converted from AC to DC. Optionally, circuitry well known in the art may be added to limit the peak inrush current which otherwise shortens the life of bulbs at turn on by more than 50%. The result of this additional circuitry is bulb life increase of approximately 3500 to 4500 hours.
One embodiment of the present invention is shown in
For packaging it is desirable to control costs and to make it palatable to consumers. One embodiment of the current invention utilizes a replacement methodology. The outer bulb enclosure 70 may be made of polymers or other translucent material that are heat/fire resistant. The outer bulb enclosure 70 may be made so as to be removable from a main standard light bulb base 110. The inner halogen bulb 60, as described herein, may be removably inserted into a secure socket 80 of a type well known in the art that is electrically connected to the power conditioning circuitry. The electronics 100 may be attached to this socket 80 and the outer bulb base 110, which may be any appropriate type such as an Edison socket as used in home lamps or style E26, E27 etc This will allow the inner bulb 60 to be replaced and the remainder of the assembly to be re-used. A potting or sealant may be utilized to encapsulate the electronics area to ensure longevity, safety and integrity of the assembly.
The improved incandescent bulb has a CRI of 100, so colors will look real, the color temperature will be somewhere around 3500K which is a cooler white, just above the current halogens. The improved bulb is made from materials so as to be shatter proof and safe around people with lower touch temperatures due to the drop in wattage. The improved light bulb does not contain any Mercury to pollute our environment; it can be manufactured more inexpensively than compact fluorescent and easier on the eyes from lack of flicker and the line spectra emitted from fluorescents.
The invention has been described in terms of particular embodiments. Other embodiments are within the scope of the following claims. For example, the steps of the invention can be performed in a different order and still achieve desirable results. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims.
This patent claims priority from Provisional Patent Application 61/039,494 filed Mar. 26, 2008 which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61039494 | Mar 2008 | US |
