US718455A - Method of treating glowers for direct-current electric lamps. - Google Patents

Description

No. 718,455. PATENTED JAN. 13, 1903.

M. W. HANKS. METHOD OF TREATING GLOWERS FOR DIRECT CURRENT ELECTRIC LAMPS.

APPLICATION FILED MAR. 23, 1901. K0 MODEL.

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UNITED STATES l ATENT OFFICE.

MARSHALL WV. HANKS, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO GEORGE WVESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

METHOD OF TREATING GLOWERS FOR DIRECT-CURRENT ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent No. 718,455, dated January 13, 1903.

Application filed March 23, 1901- Serial No. 52,651. (No specimens.)

T0 ctZZ whom it may concern:

Be it known that I, MARSHALL W. HANKs, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented new and useful Improvements in Methods of Treating Glowers for Direct- Current Electric Lamps, of which the following is a specification.

My invention or discovery relates to electric lamps of the type in which the lightemitting members, usually called glowers, are non-conductors when cold and become conductors when raised to a relatively high temperature by means of independently-generated heat, and particularly to methods of treating such lightemitting members or glowers prior to their use in lamps.

The object of my invention or discovery is to so treat glowers for use in direct-current circuits that they may have long life and a substantially constant candle-power without material change in potential during their terms of service.

If a new glower constructed and prepared for use in accordance with the practice heretofore existing is put into service in a directcurrent circuit, the potential difference between its terminals and also its candle-power are usually found to be variable. When such a glower first becomes conductive, it ap pears to have a substantially uniform degree of light emission throughout its entire length, but gradually the portion next the negative terminal decreases in brilliancy until it becomes comparatively non-luminous, and as the length of service increases the dark or relatively non-luminous portion increases in length. While this change is in progress the potential difference between the glower-terminals, and consequently the current taken by the glower, willgenerally vary to a greater or less degree. The consequence is that either the life of the glower is shortened or the efficiency is materially less than would be the case if the glower were uniformly luminous and a constant potential difference were maintained between its terminals.

I have discovered that if a glower intended for use in connection with direct-current circuits is first heated to conducting temperature and then'subjected to either a normal or an overload alternating current for a comparatively short time it may then be transferred to a direct-current lamp and there used satisfactorily with a minimum variation of potential difference and candle-power.

In general the density of the alternating current employed in treating a glower and the extent of time to which it is subjected to such current depends upon the character of the glower and its terminals. I regard a greater or less overload-current as generally preferable to a normal current, and such overload may vary with different glowers and terminals up to forty or fifty per cent. above the normal, and the time for treatment may vary from a very few minutes up to an hour or more. I therefore do not desire to limit the method to the use of currents of any specific density or to treatment for any specific length of time. The current and time are both easily ascertained by any one skilled in the art, and when determined for one of a lot of glowers of the same kind by a suitable test the remainder of glowers of that kind may be treated in the same way.

While it is inexpedient and practically impossibleto formulate an inflexible rule governing the length of time during which the glower shall be treated and the amount of current to which it shall be subjected, for the reason that different glowers require treatments for different lengths of time and with currents of diderent densities, the following may be given as an example: Assuming that each of the glower-s of a certain lot will rise ten volts in one hundred hours at a normal density of direct current, one of these glowers may be treated by alternating current at ten per cent. overload for a period of fifteen minutes, after which it may rise only five volts in one hundred hours when subjected to direct current of normal density. This glower may be again treated as before, and it is then found that its voltage remains substantially constant when subjected to a direct current of normal density for one hundred hours. The current density and the time necessary for treating each of the remaining glowers of this lot is thus determined. It follows from what has been already stated that the conditions to be followed in treating any one lot of glowers must be determined by testing a specimen from that lot.

In the accompanying drawings I have illustrated means for practicing my invention, Figure 1 being a diagrammatic representation of an alternating-current circuit and means for connecting a glower thereto for treatment, and Fig. 2 a diagrammatic representation of a lamp operated by direct currents.

In Fig. 1 the mains 1 and 2 are indicated as supplied with energy from the secondary of a transformer 3. From the main 2 a conductor 4 leads to a suitable binding device 5, and from the main 1 a conductor 6 leads to a similar binding device 7. The glower 8 to be treated has its terminals connected to the binding devices 5 and 7.

The glower may be heated to conducting temperature by a flame or by means of an electric heater, as may be most convenient.

I have shown an electric heater 9, having its terminals respectively connected to the conductors 4 and 6, though the heater may be supplied from a separate circuit or may be so connected to the mains 1 and 2 as to be automatically cut out when the glower becomes conductive.

In Fig. 2 the mains l0 and 11 are supplied with energy from a direct-current generator 12 and the glower 13. Ballast resistance 14 and heater 15 are connected in circuit in the manner usual to lamps of this class, a cut-out device 16 being employed for the purpose of automatically interrupting the heater-circuit when the glower becomes conductive.

I claim as my invention- 1. Themethod of treatingglowers to be used in direct-current lamps which consists in first heating them to conducting temperature and then transmitting through them a normal or overload alternating current.

2. The method of treating a glower for use in direct-current electric lamps which consists in heating it to conducting temperature, then passing an alternating current through it until it attains such a condition as to carry a normal direct current without material voltage variation.

In testimony whereof I have hereunto sub scribed my name this 20th day of March, 1901.

MARSHALL W. HANKS.

Witnesses:

H.-A. (Room, A. G. WEEKS.

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