The Axially-Aligned Coiled-Coil Filament Lamp and A Lamp with a Rectifying Diode in the Base
In the early 1930s tungsten lamps utilized filaments that had been coiled one time, and were, therefore, called single coils. About 1936 Burnie Lee Benbow (1885-1976) was able to achieve a reduction in length by coiling the single coil a second time; he was granted patent No. U. S. 1,247,068 in 1917. Such filaments are called coiled-coils, or double coils. Considering the 100-watt 120-volt filament, it was mounted so that the axis of the double coil was mounted perpendicular to the lamp axis. Although this engineering change resulted in an improvement in lamp performance, due in large part to the reduction in the conduction-convection loss through the gas atmosphere, a further improvement was possible. In general, gas loss from a vertically-oriented filament is less than from a horizontally-oriented one. Thus, if a lamp is usually burned base-up or base down an improvement would be realized if the coiled-coil were mounted in a vertical position.

About 1955 Charles W. Pearson, a lamp design engineer at Nela Park, took on the task of orienting the coiled-coil differently to take advantage of the reduced gas loss. The result was a filament whose axis coincided with the lamp axis. Pearson was granted U. S. Patent No. 2,877,375 on Mar 10, 1959 for this lamp improvement; the drawings from the patent are shown to the left. It can be immediately appreciated that such an improvement could be realized in lamps of various wattage values. That mounting position is still used today (2006).

Quoting from the patent:

"By changing the filament from a horizontal to a vertical position the lamp current is decreased and the light output increased at rated voltage. In addition to increased efficiency, the life of the lamp is also increased. The decrease in current signifies an increase in filament resistance which, in turn, signifies an increase in filament temperature. It is thus apparent that the filling gas in the lamp has less cooling effect on a vertically operated filament than on a horizontally operated one. The reason for the increased life is not clear. However, it is possible that equilibrium tungsten (filament) vapor pressure in the immediate vicinity of a vertically operated filament may be maintained with a lower rate of vaporization from the filament than in the case of a horizontally operated filament because of the presence of vapors which originate from a lower portion of the filament."

An advertisement appeared in the General Electric Review¹ that compared a standard crosswise filament with the new stand-up filament (CC-8) as well as the wall blackening difference between the two lamps. The pictorial difference is shown here. The advertisement read:

"General Electric announces the most important development in light bulb filaments in 42 years - a filament that stands on end. It gives up to 15% more light..."
"The 750 and 1000 watt Bonus Line G-E Lamps are available now... Other sizes from 60 to 500 watts are being redesigned to use the new stand-up filament.
"Four years of intensive research were required to solve the technical problems involved in changing from the usual crosswise position to a vertical position.
"The light gain achieved by the new stand-up positioning is a minimum of 6%. The new positioning makes it practical for the first time also to use a specially designed coiled-coil filament in bulbs of 300 watts and over. In these larger bulbs, the two improvements combine to bring the light increase to 15% during the life of the bulb...
"The new stand-up filament increases light output in two ways.
"First, the hotter a filament burns the more light it gives, and the vertical position allows the filament to burn hotter without burning out any sooner.
"Second, the effect of the bulb blackening on light output is cut to a minimum. Blackening is concentrated in the stem of the bulb when it burns base up, or ina small spot at the opposite end when burned base down.
"G-E incandescent bulbs using the new filament are called the G-E Bonus Line."

It was estimated that the extra performance of the Bonus lamps was worth about $100,000,000 a year.

Charlie Pearson also patented a lamp in which a silicon rectifier diode was mounted in the base (U. S. 3,148,303, dated Sep 8, 1964.) Drawings from that patent are shown to the left. The purpose of the diode is to allow a single filament to operate at more than one level of illumination. In a normal lamp without a diode the base has two metallic contacts on the base. In the case of a lamp with a diode there are three contact areas on the base.

The lamp can be used with a multiple contact switch socket or it can be used in normal 3-way sockets. In the case of a 100-watt coiled-coil operated in series with the recifier a current of about 0.42 ampere is drawn and the light output is about one-third the output at the normal current of 0.833 ampere.

Reference
1) General Electric Review, Jan 1956, pg 59.