Improvements in Regulating the Supply of Electricity to Incandescent Lamps.
Year: 1893

page_text: Date of Application, 4th Aug., 1893
Complete Specification Left, 4th June, 1894-Accepted, 7th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in Regulating the Supply of Electricity to
Incandescent Lamps.
I THOMAS BUDWORTH SHARP of County Chambers Martineau Street,
Birmingham do hereby declare the nature of this invention to be as follows:-
When it is required to lower the light of an incandescent lamp it has hitherto
been customary to pass the current through a resistance coil but this plan has the
disadvantage of wasting energy.
Now my invention avoids the major portion of this waste and consists in placing
a rapid make and break arrangement in the circuit in which the lamp is.
If the make and break arrangement were slow the lamp would appear to flicker
but if it is very rapid the carbon filament never gets up to its full heat on the one
hand or cools down very materially on the other but appears to be at a uniformly
lower temperature.
So if my lamp is desired full on I switch the current directly through the lamp
and independent.cf my make and break arrangement; but if I desire it partially
on I switch the current through my intermittent arrangement.
Further if I desire my lamp about half on I arrange my vibrator so as to be
passing the current about half its time or if about a quarter on I arrange it to be
passing the current about a quarter of its time and so on.
By this arrangement which cuts off the electricity instead of wasting it I save
power very nearly in proportion to the time the current is broken and the amount
of light given is much in the same proportion.
Though I prefer to use an arrangement similar to the one used in induction coil
arrangements yet I may if I choose break and complete the circuit by clockwork or
other suitable means.
Of course one make and break arrangement will do for more than one lamp.
Dated this First day of August 1893.
COMPLETE SPECIFICATION.
Improvements in Regulating the Supply of Electricity to
Incandescent Lamps.
I, THOMAS BUDWORTH SHARP of County Chambers Martineau Street
Birmingham Engineer do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
When it is required to lower the light of an incandescent lamp it has hitherto
been customary to pass the current through a resistance coil, but, this plan has the
disadvantage of wasting energy.
Now, my invention avoids the major portion of this waste and consists in placing
a rapid make and break arrangement in the circuit in which the lamp is.
If the make and break arrangement were slow the lamp would appear to flicker
but if it is very rapid the carbon filament never gets up to its full heat on the one
hand, or, cools down very materially on the other, but, appears to be at a uniformly
lower temperature.

page_text: So, if my lamp is desired full on I switch the current directly through the lamp
and independent of my make and break arrangement.
Further, if I desire my lamp about half on I arrange my vibrator or other make
and break arrangement so as to be passing the current about half its time, or
if about a quarter on I arrange it to be passing the current about a quarter of its
time, and so on.
By this arrangement which cuts off the electricity instead of wasting it I save
power very nearly in proportion to the time the current is broken and the amount
of light given is much in the same proportion.
Of course one make and break arrangement will do for more than one lamp.
In my Provisional Specification, I stated that I preferred a make and break
arrangement similar to the one used in induction coil though I might if I preferred
break and complete the circuit by clockwork or other suitable means.
Since then have made several experiments and I now find that the make
and break arrangement I am about to describe is even better than the induction coil
arrangement.
Referring to the accompanying drawings (where the same letters refer to the same
parts throughout), A is a revolving disc consisting of conducting and non conducting
material. The star B, and the stalk B' are metal conductors and connected with
one another but otherwise isolated by means of the hard wood or vulcanite washer C
and the hard wood or vulcanite backing D. On the one side pressing against the
stalk B is the conducting brush or rubber, E, which is in electrical connection with
the binding screw F, and on the other side pressing against the front of the disc A,
is the brush or rubber G, which is in electrical contact with the binding screw H.
If now this apparatus be put in circuit with the lamp or lamps and the dynamo
or other source of electrical energy and if the disc be rapidly revolved there will
be a continuous making and breaking of the current provided the brush G, is in the
position shewn on the drawing.
But by means of the screw I, the bar J. the pivot and joint K. the slot L and
the pivot M-the brush G can be placed in any position between the periphery and
the centre of the revolving disc.
It is at once obvious that the proportion of time in and out of electrical contact
can be varied accurately and at the will of the operator and that the nearer the
periphery the brush G is the lower the light will be and the nearer the centre the
brush G is the more intense the light will be. When the brush is at the centre
the lamps are full on and the disc may then be stopped and the current may then
be switched through another circuit when my apparatus will be out of circuit
altogether.
The disc may be revolved in many ways such as by a separate motor, by a band
from the dynamo, by clockwork or by numerous other methods.
The speed of the disc is not important provided it is fast enough. I revolve
mine at 400 to 500 revolutions per minute. Of course if it is on the one hand
revolved too slowly the light flickers and if on the other hand it is revolved too
quickly there is an unnecessary amount of sparking.
Of course there is nothing new in placing an incandescent lamp in a circuit
where the current is rapidly made and broken no doubt this may have been done
where it has been desired to run a small motor suitable for a low voltage when only
a high voltage circuit has been available then a lamp may have been used as a
resistance; or, for medical purposes a lamp may have been used in circuit with a
make and break when a reduced current was desirable; or, as another instance it
is quite obvious that if a low voltage lamp were put in an intermittent circuit where
the voltage was higher, then, by cutting the current a portion of the time the low
voltage lamps would not be destroyed by being worked above their proper voltage,
but my invention is essentially the placing of a lamp or lamps in circuit with an
intermittent current for the express purpose of reducing the light given out by that
lamp or those lamps and I can vary the method of producing that intermittency in

page_text: numerous ways and can vary the proportion of the time of the electrical contact.
to the time when the current is off and so vary the intensity of the light.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The method of reducing the light emitted by one or more incandescent lamp.
or lamps the voltage of which lamp or lamps is suitable to the voltage of the
circuit when not interrupted-by placing in circuit with the said lamp or lamps.
any suitable make and break apparatus or arrangement whether automatic or not
substantially as described and for the purpose or purposes set forth.
2. The method of varying the reduced light emitted by one or more incandescent.
lamp or lamps-the voltage of which lamp or lamps is suitable to the voltage of
the circuit when not interrupted-by placing in circuit with the said lamp or lamps
any suitable make and break apparatus or arrangement whether automatic or not.
which make and break apparatus or arrangement can be regulated so as to vary
the proportion of time the said apparatus or arrangement is passing the current to
the proportion of time the said apparatus or arrangement is not passing the current.
substantially as described and for the purpose or purposes set forth.
Dated this Second day of June 1894.
T. BUDWORTH SHARP.