Diode-containing Incandescent Lamp Having Improved Efficiency

Abstract

An incandescent lamp, having a glass envelope containing a gas fill and a tungsten filament, has a diode in series with the filament and positioned between the screw base of the lamp and the stem press of the lamp. The filament is made of tungsten wire having a wire weight about 50% greater than is normal for the lamp rating.

Parent Case Text

This application is a continuation-in-part of Ser. No. 335,922, filed Feb. 26, 1973 and now abandoned.

Description

This invention relates to incandescent lamps such as are commonly used for home lighting, and relates especially to A line gas filled incandescent lamps, that is, those having an A bulb and a wattage between about 40 and 150 watts.

The design of such lamps has become sufficiently standardized over the years so that the parameters of lamp construction for any particular type are almost identical between lamp manufacturers. For example, the 60 watt, A19 bulb, 120 volt, 1,000 hour life lamp of all manufacturers uses a filament made of tungsten wire having a weight of about 6.6 mg per 200 mm of wire. The efficiency of the lamp is about 14 lumens per watt.

The wire weight for the filament of a 75 watt, 120 volt 750 hour lamp is about 9.1 mg per 200 mm and that for a similar 100 watt lamp is about 12.3 mg per 200 mm.

This invention is concerned with an improvement in A line incandescent lamps that results in increased efficiency, that is to say, greater lumens per watt, without reducing the life of the lamp. Such an improvement has become especially desirable in recent years because of the growing energy shortage and the desirability of more efficiently utilizing the electric power produced in this country.

The improvement is obtained by inserting a diode between the screw base of the lamp and the stem press of the lamp, the diode being in series with the lamp filament. Such a construction does not increase the size of the lamp or the base and permits the lamps to be made on presently used high speed lamp making machines. Such a construction also does not expose the diode to the high temperatures that it would be subjected to if it were located within the glass bulb. In order to obtain the desired increased efficiency, it is necessary that the tungsten filaments be made of wire having a weight about 50 percent greater than is normally used for the particular lamp under consideration. The reason for this is that the diode rectifies the normal AC line voltage and subject the tungsten filament to a pulsed DC voltage of lower value than that of the AC voltage.

The single figure in the drawing is an elevational view, partly in section, of an incandescent lamp in accordance with this invention. The lamp comprises a glass bulb 1 having a gaseous filling, usually a mixture of argon and nitrogen for the A line lamps with which this invention is concerned. The bottom of bulb 1 is sealed to flare 2 of the usual stem press glass mount 10. Lead-in wires 3 extend through and are supported by stem press 4 of glass mount 10. A coiled tungsten filament 5 is supported between the upper ends of lead-in wires 3. Lead-in wires 3 extend downward between tipped off exhaust tube 6 and flare 2. One of the lead-in wires is connected to center contact 7 of the usual screw base 8 which is fastened to the bottom of bulb 1. The other lead-in wire is connected to diode 9 which in turn is connected to the rim of base 8, thus placing diode 9 in series with filament 5. Diode 9 may be positioned within the space between exhaust tube 6 and flare 2 or it may be positioned between mount 10 and base 8.

Filament 5 is made of tungsten wire having a wire weight about 50 percent greater than is normally used for the lamp as determined by its rating. Thus for the 60, 75 and 100 watt lamps previously mentioned, which normally use wire having a weight of 6.6, 9.1 and 12.3 mg per 200 mm, respectively, lamps in accordance with this invention would use 9.9, 13.7 and 18.4 mg per 200 mm wire, respectively.

In one example, 30 A19, 60 watt, 120 volts, 1,000 hour, medium screw base, inside frost incandescent lamps were made in accordance with this invention. Filament 5 was made of 9.95 mg per 200 mm tungsten wire and had a total filament length of 383 mm. A 1N5061 diode was connected between a lead-in wire 3 and the rim of base 8 for each lamp. The lamps were operated and measured at their rated voltage, 120volts. The average efficiency of the 30 lamps at their design life of 1,000 hours was 14.77 lumens per watt. In contrast, the efficiency of 30 A19, 60 watt, 120 volts, 1,000 hour, medium screw base, inside frost incandescent lamps used as a control and made in accordance with the prior art, that is to say, with a filament made of 6.6 mg per 200 mm wire, was 13.72 lumens per watt. The improvement in efficiency for lamps in accordance with this invention was 7.7 percent.

The prior art discloses the use of diodes in incandescent lamps for the purpose of providing different levels of illumination. In such lamps, the diode is not in the filament circuit when normal lamp brightness is desired; it is in the circuit only when reduced illumination is desired. In the instant invention, however, diode 9 is always in the circuit with filament 5. Moreover, the prior art does not suggest that lamp efficiency can be increased by the use of a diode in series with the lamp filament. In diode-containing prior art lamps, lamp efficiency is decreased about 50 percent when the diode is in the circuit. In one example of such a 60 watt lamp, the lamp efficiency was 13.5 lumens per watt with the diode out of the circuit, and only 6.3 lumens per watt with the diode in.

The filament temperature of prior art diode-containing lamps is about 2,200.degree. to 2,500.degree.Kelvin when the diode is in series with the filament during lamp operation. In the instant invention, however, the relationship of diode 9 to filament 5 is such that the filament temperature during normal lamp operation is at least about 2,600.degree.K. This filament temperature is dependent on, inter alia, lamp wattage and rated life; it varies from about 2,650.degree.K for a 60 watt, 2,500 hour lamp to about 2,875.degree.K for a 150 watt, 750 hour lamp.

Claims

1. An incandescent lamp comprising: a gas filled glass envelope sealed at its lower end to the flare of a stem press glass mount; a screw base having a center contact attached to the lower end of said envelope; two lead-in wires extending through the stem press of said mount, one of said lead-in wires being electrically connected to said center contact and the other being electrically connected to the rim of said screw base; a diode electrically connected between one of said lead-in wires and said base; and a coiled tungsten wire filament disposed within said envelope and connected between said two lead-in wires, the relationship between the diode and the filament being such that the filament temperature during normal lamp operation is at least 2,600.degree. Kelvin.