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Патент USA US2408495

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Oct. .1, 1946.
M, A, TOWNSEND
I
' ‘2,408,493
STARTING CONTROL FOR ELECTRIC DISCHARGE DEVICES
Filed Dec. 6, 1941
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Mark A. Townsend’,
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Patented Oct. 1, 1946
2,408,493
UNITED STATES PATENT OFFICE
2,408,493
STARTING CONTROL FOR ELECTRIC
DISCHARGE DEVICES
Mark A. Townsend, Cleveland Heights,’ Ohio, as
signor to General Electric Company, a corpo
, ration of New York
Application December 6, 1941, Serial No. 421,941
11 Claims.
1
(Cl. 315-100)
2
This invention relates to the control of electric
and Fig. 3 is a plan or end view of the more im
discharge devices, and is especially concerned
with the starting of such devices. The invention
portant parts shown in Fig. 2.
is very useful in connection with ?uorescent tubes
or lamps of the positive column discharge type,
and is hereinafter explained with particular ref
erence to lamps of this character and their usual
starting arrangements, as exemplified in U. S.
Patent 1,951,112, March 13, 1934, to Wels, or Pat
additional shunting modi?cation.
starting is accomplished.
Through deterioration in service or as the re
pressure atmosphere of starting gas, such as
argon at a pressure of 2 to 5 mm. of mercury, and
sult of accident, ?uorescent lamps and other dis
charge devices often or eventually become in
capable of starting and normal running, so that
the only effect of the automatic e?orts to start
such as mercury. A supply of mercury, which may
bimetal or other type of switch.-
of rare gas, such as neon at an absolute pressure
Fig. 4 is a view similar to Fig. 2 illustrating an
I will ?rst describe the portion of the circuits
and apparatus shown which have heretofore been
in use, and which permit the objectionable ?ash
ing of a defective lamp as described above.
Fig. 1 shows an ordinary fluorescent tube lamp
ent 2,212,427, August 20,1940, to Peters, for in 10 L of the positive column electric discharge type
stance.
with a tubular envelope Ill having spaced-apart
Ordinary tubular ?uorescent lamps have elec
activated thermionic cathodes H, H in its ends,
trical starting circuits which are energized and
which may be specially heated cathodes of usual
broken to start the discharge. Sometimes this
coiled~ ?lament type, and are shown connected
has to ‘be done several times before the discharge
across a power-supply circuit P including the
actually starts. For this purpose, automatic
usual ballast M, which also serves as a starting
means are commonly provided which will make
inductance, and the manual make-and-break
and break the starting circuit inde?nitely until
switch I5. The envelope I0 may contain a low
also a vaporizable and ionizable working substance
exceed the amount that will vaporize during oper
ation of the lamp L, is indicated by a drop I‘! inside
such a lamp is a continual ?ashing in it that is 25 the envelope Ill, and an internal coating of ?u
very- annoying to those in the area ‘that receives
orescent material or phosphor l8 on the envelope
the light of the ?ashing lamp, besides uselessly
walls is also indicated. A starting and electrode
wearing out the starter device. Usually such in
heating circuit H is shown connected across the
capacity for starting is dueto loss of electron
circuit P through the ?lamentary cathodes I I, I I,
emission from one or both electrodes of the lamp, ' with a starting switch S included therein, which
which may result from dissipation or other loss
may be of thermal type.
of activating material on which the emission de
The general mode of operation in starting the
pends. The objectionable flashing of such a lamp
lamp L with this circuit arrangement is that when
goes on inde?nitely, until the power supply is shut
the switch I5 is closed to turn on the lamp L, the
off, or the lamp is removed from the circuit.
'
switch device S permits ?ow of currentv through
The purpose of my invention is to obviate the
the circuit H and the cathode ?laments H, II in
undesirable ?ashing of defective lamps without
series therein for a su?icient length of time to pre
interfering with repetition of the attempts to start
heat the cathodes to an adequate emissive tem
as long as there is any reasonable promise of suc
perature, and then suddenly opens the circuit H;
cess. This I accomplish by rendering the starter 40 and the resulting voltage kick across the cathodes
ineffective to open the starting circuit. I have
H, II sui?ces to initiate discharge between them,
shownand explained the invention as ‘applied to
or, in other words, starts the lamp.
a closed glow-switch‘ type of starter. The glow
As shown in Figs. 1 and 2, the thermal switch
switch illustrated is of double bimet'al type; but
S is of glow-switch type, comprising a glass en
the invention is equally applicable to‘ a single
velope 20 containing a low-pressure atmosphere
'
.Various features and advantages‘of the inven
tion will become apparent from the description
of species and forms of embodiment, and from
of 50 mm. of mercury. The envelope ‘20 may in
clude a stem 2| through which are sealed current
leads 22, 23 that are connected to opposite sides
the drawing.
'
50 of the circuit H, and are provided with terminals
In the drawing, Fig. 1 is a diagrammatic view
orv electrodes inside the envelope between which
of a fluorescent tube or lamp with circuit connec
a glow discharge takes place when the switch I5 is
tions including my invention; Fig. 2 is a tilted or
?rst closed. In the switch S here illustrated, both
perspective view of parts of a starting switch ap
these terminals or electrodes consist of slender,
paratus suitable for the purposes of my invention; 55 straight approximately upright thermostatic bi-'
2,408,493
3
4
metal strip members 25, ‘26 attached to the leads
22, 23, as by welding, and coacting as both tem
perature-responsive elements and contacts for
the switch S, Accordingly, contact pieces 21, 2'!
order to prevent continued flashing or blinking
of the lamp.
(as of molybdenum) are shown welded to the free
A simple control for this purpose is shown in
Figs. 1, 2 and 3 as comprising an additional or ex~
traneous shunting thermostatic bimetal strip
Ll
These members
member 30 that closes the heating circuit H more
25, 25 should be identical in order that they may
heat and ?ex alike, and must be slender enough
to keep the glow discharge current between them
or less independently of the thermostats 25, 26,
so low as to assure starting of the main discharge
words, the bimetal 35 when sufficiently heated
shunts both the contacts 27, 21 themselves and
ends of these members 25, 26.
and may, as here shown, suspend their further
operation when it closes said circuit. In other
between the electrodes ll, ll when the contacts
27, 27 separate and break the circuit H, as ex
the path of current ?ow provided by the con—
ductive supporting members 25, 2E and the gase
ous atmosphere in the envelope 20. This ther~
most-at 33 may conveniently (though not neces
sarily) coact with the members 25, 26 rather
than with their leads 22, 23, and may be arranged
with its opposite ends in position to engage these
members. A compact and convenient arrange
ment is for the slender strip member 30 to be
plained hereinafter.
The general operation of such a switch S is
that when the circuit H is energized as a result
of closing the hand switch IS, a glow discharge
takes place across the gap between the parts 25,
26, shunting their co-operating contacts 21, 21.
The conducting path for this current flow, which
produces heat to heat the thermostatic bimetals
25, 26, is provided by the gaseous discharge at
mosphere in the envelope 20, already mentioned.
The discharge heats the members 25, 26 until
they bend sufficiently to bring the contacts 21, 21
together to touch one another, thus closing the
circuit H and shorting out the glow discharge.
bent as shown in Figs. 2 and 3 almost into an
elongated loop or oval which is disposed in a
horizontal plane at a level where it surrounds the
region of the glow discharge, and approximately
perpendicular to the approximately upright mem
bers 25, 2G, with its ends adjacent the latter.
The thus augmented ?ow of current in the cir
cuit H continues long enough to heat the fila
mentary cathodes l l, l I to an adequate electron
The member 30 may be supported about at its
own midlength by an upright wire standard 3|
welded to the member 36 and fused to the glass
emissive temperature; and by the time this has
been accomplished, the thermostatic members 25,
26 cool sufficiently to open the circuit H and start
the main discharge between the electrodes I I, l l,
as already described. After the main discharge
has started, the voltage on the device S is no
longer high enough to maintain any discharge
across the gap between the parts 25, 26..
If, however, the main discharge does not start
on the voltage kick due to the opening of the cir
cuit H by the switch S as just described, a glow 40
stem 2i, and its fixed mid-portion is preferably
discharge again takes place between the parts
25, 26, and the switch S again closes and opens,
just as before; and if this effort is not success
ful in starting the main discharge, it is repeated,
and so on. In other words, the contacts 21, 2‘!
alternately engage and disengage, over and over
again, at short intervals. If the main discharge
cannot be started at all, the lamp L would (with
the circuit arrangement and parts so far de
scribed) go on to ?ash in the objectionable man
ner described above.
close to the zone of the gap between the members
25, 26 where the heating effect from the discharge
is greatest. As shown in Figs. 2 and 3, the mem
her (it has contact pieces 32, 32 (as of molyb
denum) welded to its ends, both of which are
free to move as the member 30 ?exes in response
to temperature changes.
In starting a good lamp L, the starter S func~
tions in the usual way, just as if the control ther
mostat 30 were absent; 1. e., this control does
not enter into the action of the starter S, even
though several operating cycles of the starter S
should occur before the lamp L actually starts.
This is because the member 30 is heated (like
= the members 25, 25) only during the glow dis
charge, and is less directly exposed to the heat
of the discharge than the members 25, 26 which
serve as electrodes for the discharge. In the case
of a defective lamp, however, the cumulation of
heat in the thermostatic member 30 due to the
glow discharge while the starter switch S is open
(during repeated cycles or starting attempts of
In accordance with my invention, means of
control are provided for determining the condi
the starter) causes the member 39 to ?ex more
tion of the circuit H as to continuity in such a
and more, until eventually one end of it (or one
way that after reasonable efforts of the starter in iV! of its contacts 32, 32) engages one of the mem
bers 25, 26, thus connecting it into this side of
S to start the main discharge, a closed condition
of circuit H that prevents flashing of the} lamp
L is established and maintained, independent
the glow discharge circuit. Thereafter, the glow
discharge takes place between the other of the
members 25, 26 and the member 38, heating the
and regardless of any further action or oper
ation of starter S. For this purpose, automatic 60 latter until it ?exes into engagement with the
other of the members 25, 26 thus shorting out
control means may be employed whose period of
operation (as fixed by design and adjustment) is
long enough to include whatever number of at
tempts by starter S may be considered reason
ably worth-while; e. g., a period of some seven
to ten seconds under favorable voltage conditions,
embracing some ?ve to ten attempts, say. The
action of this automatic control need not be an
arbitrary matter of ?xed adjustment, however,
but can be made responsive to the actual attempts
of starter S to start the main discharge. As
already mentioned, the particular control here
illustrated determines the continuity of the cir
cuit H in the positive sense-by closing it—in
the glow discharge, and, in effect, establishing a
shunt around the glow switch S. In thus shunt
ing the contacts 21, H, the thermostatic mem
.' her 3!! responds to heat produced by current flow
in the path afforded by the gaseous atmosphere
in the envelope 20, and accumulated during suc
cessive intervals or periods of such current flow,
though more slowly or in a lower degree than do
the bimetals 25, 25. Under this condition, the
member 30 (owing to its slenderness) functions
as a heating resistance and is heated by the short
circuit current through it sufficiently to keep it
?exed and maintain the shunt indefinitely. Cur
rent thus ?ows continuously in the circuit H,
awaits
6
U
without any possibility of interruption by action
of starter S, and the lamp L ceases to ?ash. ‘The
springs", elastic members 25, 26 yield to any pres
outer corners of the members 25, 25 may be, 117
inch each at ordinary atmospheric temperature.
sure of the member 30, and the member 30' also
50 mm. of mercury, and zinc-coated members
25, 26, such a glow-switch is especially well
With a ?lling of neon at an absolute pressure of
yields elastically under such pressure. Thus con
adapted for use with a standard 100-watt ?uores
cent tube of positive column type. For lamps of
tact is maintained as long as current flows in
the circuit H, even though the members 25, 25
may cool somewhat and tend to open.
other wattages, some variations of design and of
1
the gas ?lling and its pressure may be found ad
However, if the circuit H is tie-energized’ (by
opening the hand switch [5, or by removing the
10
defective lamp L and replacing it with a good
one), and is allowed to remain de-energized long
enough for the control thermostat 30 to cool off
fully, the shunt will be opened, and the starter S
will again be ready to- start the lamp in the
visable. In‘ particular, the zinc coating on the
members 25, 25 and the nature and pressurepr
the gas ?lling influence the glow voltage and the
closing time of the device, and the zinc coating
itself stabilizes the glow voltage and tends to
Fig. 4 illustrates a glow switch device generally
reduce the time of operation of the switch.
Moreover, it may be desirable to place a small
amount of uranium oxide (e; g, 20 mg.) on the
similar to that in Figs. 2 and 3, but different as
interior surface of the switch envelope 2i], at‘it's
regards the arrangement and con?guration of
top (as indicated at 35), in order to make the
usual manner.
15
I
the extraneous control thermostat 3011. Instead 20 operation of the switch independent of whether
it is in darkness or exposed to the light, as set
of being in a horizontal plane perpendicular to
forth in applicationSerial No. 403,572, ?led July
22, 1941, by Basil N. Clack, and assigned to the
the thermostatic members 25, 26, the thermo
static member 3011 is arranged in a vertical plane;
and in outline it is a less complete loop, of an
inverted angular U-con?guration. This allows
the member 30a to‘ be made longer, to surround
the region of the glow discharge more completely,
and to be more effectively heated by the glow dis
charge. As shown, the inverted uemember 30a
assignee of this application.
25
_
What I claim as new and desire to secure by
Letters Patent of the United States is:
1. The combination of an electric discharge
device having a starting circuit comprising aura:
matic switch means responsive to energization’ of
is arranged like a door frame around the mem 30 the circuit for interrupting it to start a discharge
in the device, and extraneous shunting means
bers 25, 26, in a plane approximating the planes
also responsive to energization of the circuit for
of these members, and the upper end of its sup
closing the circuit independently of said switch
porting wire 3| is bent over across its horizontal
means and suspending further operation of the
middle segment. When this thermostat 30a
closes, its free ends (or their contacts 32, 32‘) en-'
gage against the edges of the ?xed lower ends
of the members 25, 26, which are Virtually mere
ends of the leads 22, 23.
In Fig. 4, various parts and features are marked
with the same reference numerals as in Figs. 1-3,
in order to dispense with repetitive description, a
distinctive letter being added where such dis
tinction appears desirable. The operation of the
latter after repeated operation of the switch’
means has failed to start the discharge.
,
_
2. The combination of an electric discharge
device having spaced electrodes, a starting cir
cuit for said device comprising automatic switch
means connected across and between said elec
device as shown in Fig. 4 is essentially the same
as already described in connection with Figs. 2
trodes and responsive to energization of the cir
cuit for interrupting it to start a discharge be
tween said electrodes, and extraneous shunting
means also responsive to energization of the cir
cuit for closing a shunt circuit between said elec
and 3.
trodes around the switch means and suspending
I
For the convenience of those wishing to use my
invention, illustrative particulars of a device S of
further operation of the latter after repeated
operation of the switch means has failed to start
the Fig. 4 type are here given:
the discharge.
‘
a
The thermostatic strip members 25, 26' may be
3. The combination of an electric discharge
formed of the bimetal commercially known as
“Chace #3300 bimetal,” composed of laminae of
Invar, an alloy of 64'per cent iron and 36 per cent
nickel, and of nickel, in equal thicknesses, welded
together and coated with zinc on both sides.
Each of these strips 25, 26 may be 0.015 inch
thick, % inch wide, and 0.43 inch long, and the
normal gap between their contacts 21, 21 when
device having spaced electrodes, a starting cir
cuit for said device comprising automatic switch
they are at ordinary atmospheric temperature
may be 0.022 inch. The thermostatic strip mem
ber 30a may be formed of the bimetal commer
cially known as “Chace #2400 bimetal,” com
posed of laminae of the Invar above mentioned
and of chrome iron (which is an alloy of '75 per
cent iron, 22 per cent nickel, and 3 per cent chro
mium) in equal thickness, welded together but
uncoated. This strip 30a may be 0.004 inch thick,
T16 inch wide, and 1.18 inch long before being
means connected across and between said elec-'
trodes and responsive to energization of the cir
" cuit for interrupting it to start a discharge be
tween said electrodes, and automatically reset
table extraneous shunting means also responsive
to energization of the circuit for closing a shunt
circuit between said electrodes around the switch
means and suspending further operation of the
latter after repeated operation of the switch
means has failed to start the discharge, said
shunting means being constructed and arranged
to maintain its closed circuit position only so
long as current continues to flow through it.
4. In combination, an electric discharge de
vice having spaced electrodes adapted to be pre
heated by current flow therethrough, a ballast
for said device, means including said ballast for
connecting one end of each of said electrodes
with a source of current supply, and thermal
switch means comprising co-operating contacts
connected between the other ends of said elec
trodes and including heat supplying means and
bent as shown in Fig. 4. In its bent form, its
parallel legs may be 0.44 inch long each, and
spaced 0.30 inch apart, so that its horizontal top
portion may be 0.30 inch long. The distance be
tween this top portion and the upper corners of
the members 25, 26 may be 0.04 inch, and the
gaps between the parallel legs and the lower 75 means responsive to the heat produced by said
2,408,493
7
8
heat supplying means for alternately causing one
tacts into engagement with the other contact
of said contacts to engage and disengage the
whereby said contacts alternately engage and
other contact and thereby attempt to start the
disengage each other, and extraneous shunting
device, and thermostatic shunting means respon
means responsive to the heat accumulated dur
slve to the resulting current flow for closing a Si ing a plurality of successive intervals of current
shunt circuit around the switch contacts upon
flow in said path to close a shunt circuit around
accumulation of heat therein during a plurality
of successive attempts of the switch to start the
the said contacts and thereby terminate further
operation of the switch, said shunting means
comprising a bimetallic strip having a resistance
5. In combination with an electric switch com 10 such that the flow of current therethrough after
prising means for automatically and repeatedly
it has closed the shunt circuit keeps it heated
closing and opening its contacts, extraneous shunt
and flexed in circuit closing position.
means operable upon energization of the switch
10. A thermal switch comprising a pair of nor
device.
for closing a shunt circuit around the switch
mally spaced co-operating contacts, conductive
contacts after a predetermined period of opera 15 support members for said contacts, at least one
tion of the switch.
of said support members being a bimetallic strip,
6. In combination with a thermal switch com
means providing a current conducting path shunt
prising means for supplying heat to automati
cally and repeatedly close and open its contacts,
extraneous shunt means responsive to the heat
produced by said heat supplying means for clos
ing a shunt circuit around the switch contacts
upon accumulation of heat therein during a pre
determined period of operation of the switch.
'I. In combination with a thermal switch com
prising means for supplying heat to automatical
ly and repeatedly close and open its contacts, ex
traneous shunt means responsive to the heat pro
duced by said heat supplying means for closing
a shunt circuit around the switch contacts upon
accumulation of heat therein during a predeter
mined period of operation of the switch, said shunt
means being a heat-deformable member having
a resistance such that the flow of current there
through after it has closed the shunt circuit keeps .
it heated and ?exed in circuit closing position.
8. A thermal switch comprising a pair of nor
mally spaced co-operating contacts, means pro
viding a current conducting path shunting said
contacts, means responsive to heat produced by
current in said path for moving one of said con
tacts into engagement with the other contact
whereby said contacts alternately engage and
disengage each other, and extraneous shunting
means responsive to the heat accumulated dur- 1.
ing a plurality of successive intervals of current
?ow in said path to close a shunt circuit around
the said contacts and thereby terminate further
operation of the switch.
9. A thermal switch comprising a pair of nor
mally spaced co-operatingcontacts, means pro
viding a current conducting path shunting said
contacts, means responsive to heat produced by
current in said path for moving one of said con
ing said contacts and supplying heat to said
bimetallic strip to cause it to carry its contact
into engagement with the other contact where
by said contacts alternately engage and disen
gage each other, and an extraneous shunting bi
metallic strip mounted with its ends adjacent to
but normally spaced from the respective contact
support members, said shunting strip being re
sponsive to the heat accumulated during a plu
rality of successive intervals of current flow in
said path to carry its ends into engagement with
the respective contact support members and
thereby close a shunt circuit around the contacts.
11. A thermal switch comprising a sealed en
velope containing an ionizable medium, a pair of
bimetallic strips ?xedly supported at one end
in said envelope and carrying contacts at their
free ends, said strips being spaced for a glow
discharge therebetween and being arranged to
flex toward each other to carry said contacts
alternately into and out of engagement with each
other, and another slower acting bimetallic strip
supported intermediate its ends in position to
be heated by said glow discharge and having
its free ends adjacent to but normally out of
engagement with respective ones of said pair of
strips, said slower acting strip being arranged to
?ex in a direction such that its ends are carried
into shunting engagement with said pair of strips
upon accumulation of heat therein during a plu
rality of successive intervals of current ?ow in
the glow discharge, said slower acting strip hav
ing a resistance such that the ?ow of current
therethrough keeps it heated and ?exed in cir
cuit closing position.
MARK A. TOWNSEND.
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