US1428834A - Electric resistance for regulating the candlepower of electric incandescent lamps - Google Patents

Description

G. l. BJERRE. ELECTRIC RESISTANCE 50R REGULATING THE CANDLE POWER OF ELECTRIC INCANDESCENT LAM PS APPLICATION JILED IAY 4.192].

Patented sept. 12, 1922.

Patented Sept. 12, 1922.

UNITED STATES PATENT OFFICE.

GRAVERS JACOBSEN BJERRE, OF COPENHAGEN, DENMARK.

ELECTRIC nnsis'rANcn FOR REGULATING THE GANDLEPOW ER or ELECTRIC ,INCAN- .IDESGENT LAMPS. 1

Application filed May 4,

To all whom it may concern Be it known that I, Gnavnns JAcoBsnN Banner, a SLll316Ctof the King of Denmark,

residing at Copenhagen, in the Kingdom of Denmark, have invented certain new and useful Improvements in Electric Resistances for Regulating the Candlepower of Electric Incandescent Lamps, of which the following is a specification.

The present invention deals with an electric resistance for the regulation of the candle-power of electric incandescent lamps.

It has previously been proposed to regulate the candle power of incandescent lamps by making use of a resistance inserted in the circuit of the lamp. Said resistance consisted of some secondary or badly conducting material, for instance graphite, carborundum-powder or the like which was placed in an insulated holder in which two electrodes are introduced, both of which contact with the sandy material, at least one of which can be moved in such a manner that it can push into the material compact it and thereby cause the ohmic resistance of the apparatus to be altered.

It has proved in apparatus of this description that when the movable electrode is introduced into the powdery material cavities are easily formed, the shape of which corresponds to that of the end of the electrode, so that only a very unreliable regulation is obtained, because the electrode does not come gradually into contact with the powdery material when it is introduced into same, but only suddenly namely when the electrode fills the cavity in the material.

As a result no accurate regulating of can-. dle power can be obtained and the regulating is further disturbed by the sandy material, which as a rule forms an adhesive column, breaking apart so that the current is thus cut off and the lamp is extinguished and the state of aggregation of the material is greatly changed.

The present invention ensures a very accurate regulation of the candle power from darkness to full power, even if the apparatus is subjected to shock when in use.

The desired result is, according to the invention, obtained in the following manner: The holder containing the powdery material is an U- or V-shaped tube the branches of which are directed downwards, and in each of which branches is inserted an electrode,

branches 2 and 8.

1921. Serial No. 466,650."

the tube. The total ohmic resistance of the sandy -material will thus be altered by the resistance in the'bent part of the tubebe ing increased or diminished according as said part is more or less filled with the material.

: Further particulars are shown on the drawing which is a side view of the apparatus. a

1 is a bent tube made of suitable insulated material. An electrode 4 and 5 is introduced into each of the downward directed The ends of these electrodes are in the form of pistons sliding in the tubes. The space between the electrodes 4, 5 in the tube is partly filled with a variable resistance consisting of a sandy material, for instance powdered granite, carborundum or the like secondary or badly con ducting material. One of the electrodes, 4, can by means of a lever8 be moved up and down inside the tube. The cross-sectional variation at the bend will be ell ected purely by gravity, and the state of aggregation or coherence will be substantially the same under all conditions of cross-sectional change. The apparatus works in the following manner: If the electrode l be lowered by means of the lever 8 the sandy material in the tube branch 2 will move downwards thus causing the surface 6 of the material in the bent part of the tube to sink downwards. The current carrying part of the section marked wzr on the drawing will therefore be diminished and the ohmic resistance will, consequently, be considerably increased, thereby diminishing the current, which latter will become zero at the moment when the sandy material has sunk so low that the two 4 as shown, both electrodes may be moved, by means of levers as shown or by means of screws or the like.

The apparatus can be fixed in the foot of a table lamp or at the switch of the lamp or in any other place in the circuit.

I claim:

1. An electrical resistance comprising a bent tube, a granular resistance, conducting terminals contacting with said resistance and means to move at least one of said terminals to vary the cross-section of the resistance at the bend of said tube.

2. An electrical resistance, comprising a tube, a granular resistance material therein and means to change the conductive cross section of the material Without substantially changing the state of aggregation or coherence of the material.

8. An electrical resistance, comprising a tube, a loose granular resistance material in said tube and means to permit bodily gravitational movement of the material in said tube and thereby diminish the cross-sectional area of said material.

4. An electrical resistance, comprising a tube, a loose granular resistance material in said tube and means at opposite ends of the column of material in the tube to cause by gravitational action a variation of cross section at one part of said tube.

5. An electrical resistance, comprising abent tube, a granular resistance, conducting terminals contacting with said resistance and means to move at least one of said terminals to vary the cross-section of the resistance at the bend of said tube.

In testimony whereof I allix my signature.

GRAVERS JACOBSEN BJERRE.

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