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Патент USA US2150356

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March 14, 1939.
C)I C; BLE|CHER
2,150,356
GLOW DISCHARGÈ LAMP I
Filed July 21, 195e
un”
„HMVA
/NVE/VTÓR
O. C. BLE/CHER
By
[email protected]
. Patented Mar, >14, i939
_ ~2,150.3.'36 „
UNITED. sita'l‘ris4 _PATENT - OFFICE
.
`2,150,356
GLOW DISCHARGE LAMP
, otto c. ßleicner, Brooklyn, N. Y., assigner to
'
Bell Telephone Laboratories, Incorporated, New
York, N. Y., a corporation of New York
,
' - Application July 21, 1936,' Serial No. 91,642
_.
'z-olaims. (ci. 17e-_122)
This invention relates to glow discharge de
vices .and more particularly to positive column
lamps;
`
. .` '
'
United States Patent 1,912,146, issued May 30,
5' „1933, to J. B. Johnsonwdiscloses -a positive col
umn glow lamp vcomprising an enclosing vessel
, charged with a mixture of a monatomic and a
diatomic gas and including a cylindrical cath
ode, a glass support which surrounds the cath> ‘
inV ode, _engages its outer surface and extends be-'
yond it, the extension'being provided with a
. capillary opening, and` an apertured anode. The
cathode, capillary opening andv aperture in the
anode are axiallyy aligned, and the discharge,
-ionization of the gas charge, this member may
be temporarily connected to the anode to provide,
in effect, an auxiliary anode adapted to cooper
ate with the cathode to constitute a path over
which an initial discharge readily takes place. 5
Once this auxiliary discharge is started, the main .
discharge path is readily bridg‘èd by the normal
operating voltage impressed between the main`
electrodes.
.
_
'
A description of the invention follows and is v1li
illustrated in the attached drawing, in which
Fig. 1f is a sectional view taken axially of a.
lamp embodying the invention; and
Fig. 2 is a plane view of the lamp shown in
«
15 which occurs. between the inner surface of the Fig. l.One disadvantage of glow lamps of the type
cathode and the walls' of the anode aperture, to be hereinafter described, which have been dis
passes throughand is concentrated in'the cap
illary opening to> provide an intense spot of light closed in the prior art, is that they operate to
produce oscillations in the discharge path, when
which may beusefully employed in signalingsys
20 tems, for example, in sound recording, picturel the electrodes are supplied with varying poten- 20
transmission and television systems.
»
f An object of this _invention is to provide a
lamp of the type described above` having im
proved .operating characteristics.`v ï
25 _ Another object is to provide a glow discharge
lamp in which the breakdown and >extinction
voltages are substantially alike.k
.
»
A feature of theinvention relates to the use
.
of a metallic member having a taperedy capillary
30 opening through which the discharge passes.1
,
Another feature‘relates to the use of the me
tallic member, as an auxiliaryanode to effect
breakdown of the discharge path.
\
Y
In accordance with one embodiment of the in
_ 35 vention, vthe discharge device comprises a trans
parent vesselwhich encloses a cylindrical cathode,
extending axially of the vessel, and an apertured
anode,l a metallic member intermediate the cath
ode and anode, and containsa gaseous atmos
40 phere, such as a monatomic gas.. The metallic
i member comprises ,a cylindrical portion sur
rounding the cathode, and a portion which tapers
ina direction toward the anode and is provided
with aitapered capillary opening. The cylindri
_ 45 _cal cathode-.capillary opening and anode aper
ture are axially' aligned, vand the positive col
umndischarge ybetween the- electrodes passes
through and is concentric in the capillary' open
ing to produce laspot of light of great brilliancy,
50 the intensity of.which readily and faithfully fol
lows variations in the potential applied between
the electrodes. _
-
.
_
' Under normal _operating conditions, the me
tials. ` The oscillations are ofla frequency which
is independent _of the rate of variation of the
applied potential, and appear to be caused by
an after-ionization or after-glow, resulting from
the fact that the walls of the capillary _opening 25
becomes negatively charged and acts as a third
electrode to cause ionization aftery each cycle. of
change in the applied potentials. While the am
plitude of theä oscillations could be decreased by
varying the -pressure of the gas charge and could 3o -
_ be completely eliminated by this expedient when
varying direct current potentialswere supplied
to its electrodes, it was found impossible to elimi
nate them when the lamp was suppliedwith po
tential variationshaving diiîerent frequencies.>
35
Again, when alternating current potentials
were applied to the electrodes of a lamp of the
earlier type and thefrequency of the potential
was increased, a loop appeared in its voltage-current characteristic curve.
I
Electro-optical systems, such as for example,
picture, television and sound recording an'd re
producing systems involve the use of signal po
40
tentials which include variations extending over .
a wide ’frequency band. In certain cases this 45
bandmay extend from substantially zero fre
quency to an upper hunting frequency of sev
eral thousand cycles or even a million or more
cycles for high qualitytelevision operation, and `
it has been proposed to apply such signal poten- 50
tials to a glow discharge lamp to control thev
production.l of a record or an image of a remote
field. It has also been proposed to apply a po
tential varying. at a carrier` frequency rate to
tallic member isinsulated from the electrodes, ' lamps
of this type for the purpose of producing 55
but for> starting purposes, i. e., to effect initial
2
2,150,856
_carrier modulated light which -is used to illuminate or scan a picture, a photographic record or
an image ñeld. _For distortionless operation it is
essential that the >intensity'of the light supplied
by the lamp faithfully follow the amplitude vari
ations ofthe applied signals or carrier varia
tions.
-
-
-
The amount of distortion resulting from the
operation of lamps of the type disclosed in the
10 prior art including'that in the above-mentioned
-normally disengaged, the conductor wire 2l is dis
connected from the ,supply source and, as a result,
the member 6 is not supplied with energizing
potential.
.
`
‘
When it is desired to initiate a discharge within
.the lamp, push-button 25 is actuated to connect
the conductor 2I to the lead-in wire I6 and there
by cause normal operating potential to be applied
between the cathode 3 and member 6. A dis
charge having been initiated between this member 10
and the cathode itwill be readily transferred to
the anode 4. When this occurs, the push-button
is released, the memberv 6 is disconnected from the
energizing source and, normal operating potential
15 vides a construction which possesses many ad-v
being applied between the cathode 3 and anode 4, 15
vantages over those- earlier disclosures, chief of the positive column discharge occurs between
which is, that it can be supplied with energiz'-` these electrodes.V This discharge passes through
ing potentials of varying frequencies without ' the capillary opening in the metallic member 6
causing the production of oscillations or a loop
-20 in its voltage-current characteristic curve, due ‘ and is concentrated to produce a small spot of
light of extremelyv high ' brilliance as viewed 20
to frequency changes.
`
through the aperture 5. 'I'his light spot can be
patent to Johnson is well within permissible lim
its under certain given operating conditions and
hence they may be satisfactorily used for many
purposes.V However, the present invention >pro
Referring to the drawing, there is shown a directly used- to scan a picture, sound track, re
lamp comprising a bulb I,having. a reentrant stem „cording surface or nlm or may be used with an
`2 »and enclosing a cylindrical cathode 3, a disc
optical system for illuminating or scanning an '
25 shaped anode 4, provided with an aperture 5, and object or ñeld of view.
25
a member 6 having 'a cylindrical portion 1, con
The cylindrical portion of the member 6 has a
" centric with the cathode, and a cone-shaped ex
tension 8, having a capillary opening 8’.
The bulb contains a charge consisting of mon
30 atomic gas or'a mixture of monatomic gases. If
desirable, the charge-may- include, in addition to
the monatomic gas or gases, a small quantity of
.diatomic gas, the amount being ofthe order given
- in and for the purpose disclosed in United States
35 Patent 1,871,266, issued August 9, 1932, to F. Gray.
Encircling the stem 2 is a band 9» provided with
rods Ill and II for supporting the member 6 and
the anode 4. These elements are mounted with
the opening in the cathode, ‘capillary opening in
40 the extension 8 and the aperture 5 in the anode
axially aligned, and the anode is Supported from
the member 6 by short rods I_2 each including 'an
insulating bead I3, whereby the member 6 is
insulated from the anode 4.
I45
50
'The reentrant `stern terminates in a press I4
diameter many times that of the larger end of the f
capillary opening, and its length should preferably
be-approximately one and a half times the length
of the conical section including the capillary. 30.
The member, therefore,l constitutes ‘an element
having a large superficial area compared with that
of the capillary opening, and since it is made of
metal, the charge imparted to the walls of the
capillary by the passage of the luminous discharge 35
will continuously leak along the surface of the
member and thereby cause the latter to become
substantially uniformly charged at a potential
which does not materially differ from that of the
cathode. Consequently, under normal operating 40
conditions, this member Will not act as an auxil
iary electrode to produce after-ionization or after
glow and hence will not-cause oscillations to be set
up in the discharge path.
.
For satisfactory use in electro-optical systems,
the electrical requirements of a discharge lamp
through which a leading-in wire I5 passes to the
cathode 3. A leading-in wire I 6 passes through are that the exposure versus current relation
the wall of the stem 2 and extends tò the anode 4. 4should preferably be linear, the light of the dis
This leading-in wire is surrounded by an insulat
charge glow should be concentrated so as to obtain
ing sleeve I'I, to prevent discharges between it andì maximum brightness, the variation of light in
50
the cathode.
'
‘
a
tensity between maximum and minimum bright
The lamp is provided with a base I8, having a n_ess sholild be great enough to give sumcient
pair of contacts I9, respectively connected to the I contrast, the breakdown voltage and extinction
leading wires I5 and I6, and a switch. The elec
voltage lshould be low and the difference between
55 trodes of the lamp are adapted to be connected to these two voltages should be as small as possible, 55
an energizing source via the contacts I9, and the ‘
switch is'provided to permit a conductor 2|, ex
tending to the member 6, to be connected to the
lead-in wire I6, whereby the anode potential may
v60 be simultaneously applied to this member and the
anode. The lead-in wire 2| is also surrounded by
an insulating sleeve 22, to prevent the occurrence
the frequency characteristic should be good, thelamp should have a long useful life, and it should
be reproducible. While these desirable charac
teristics are partially contradictory, a satisfactory
compromise between the conflicting requirements 60
was attained‘ by providing a lamp including an
assembly comprising a disc-shaped anode having
of discharges between it and the cathode 3. - a rectangular aperture, a glow discharge concen
Under conditions to be hereinafter described,
65 member 6 may be used as an auxiliary anode
which cooperates with the cathode to constitute a
relatively short path over which a discharge may
'be initiated for starting the lamp.
trating member having a cone-shaped portion,
provided with a taperedcapillary opening, integral 65
with a cylindrical portion which completely sur
rounds a tubular cathode.
In a typical design of
lamp, which has been successfully operated, the
The switch comprises a pair of co tacts 23 and . anode, concentrating member, and cathode, were
70 24, respectively connected to the lea -in wire I6
of nickel, and the aperture in theanode, the capil 70
and the conductor` 2 I , and contact 24 is adapted to lary opening and the cathode were axially aligned,
be moved into engagement with contact 23 by a
push-_button 25, which extends through the side
wall of the base and is held in'the position shown
by a spring 26, whereby the switch contacts are
and the enclosing bulb contained a charge of pure
helium or pure neon.
One surface of the anode
was separated from the apex of the cone-shaped
portion of the concentrating member by a thin
3 .
2,150,856
from a tungsten' lamp, activated by the
insulating disc, provided `with an aperture which nated
light radiated from the glow=discharge produced
-
' was slightly larger than that in the, anode and
in helium. The resiilts serve to illustrate the
somewhat smaller than the diameter of that in '' fact
that for current variations of the order com
the apex of the cone-'shaped element.
n
’
monly used in picture and sound recording sys
'I'he cathode was a thin walled tube and had an tems, the lightintensity may be controlled to
internal diameter-of approximately'eight milli
wide variations in contrast.
`
meters. The internal diameter ofthe cylindrical provide
Again, lamps of the type described above were
portion of the concentrating member was sub-l supplied with energy from a direct current source
stantially twice that of the cathode, and it ter
and their voltage-current k"characteristics were 10
10 minated in a plane more remote from the base
>of the cone-shaped portion than that occupied by
the corresponding terminal of the tubular cath
ode.
Thus the cylindrical portion of the con
centrating member is spaced apart from andis
15 concentric `with the cathode, and'its length is
such as to preclude the possibility `of a discharge
occurring between the cathode and the anodel
over a'path extending along the outer surface
of the concentrating >member and around its
base; In other words, it insures that the dis
charge between the electrodes will pass through
the capillary opening, which tapers from a di
ameter of five millimeters at the base of the cone,i. e., adjacent the near end of the cathode, to a
diameter of 1.5 millimeters at its apex, or adja
cent the anode.
_
r
The use of the metallic member having a capil
measured. Certain of 'the lamps contained a gas
charge of lpure helium, while the gas charge in
others was pure neon. In general they were so
designed that a glow discharge was initiated by
lapplying a direct current potential of approxi 15
mately 350 volts across the cathode and anode.
When the push button switch was operated to
connect the concentrating member to the anode,
a discharge was initiated by the application of a
potential of- about 200 volts. As the voltage-was
increased the current fiow in the discharge col
umn increased substantially linearly and the glow
discharge, in the helium lamps being tested, was
interrupted when the applied voltage was reduced
to approximately 225 volts and, in the neon lamps
under -test, the glow discharge was interrupted
when the applied voltage was reduced to about
230 volts. In other words, the breakdown voltage
lary opening, in place of a concentrating element v was- reduced from 350 volts to approximately 200
of insulating material provided with a capillary volts, and the extinction voltage of the respective 30
30 opening, resulted in the provision `of a positive lamps was 225 and 230 volts. When a current of
column lamp which can _be supplied with energiz
constant amplitude but which varied in- frequency
ing potentials extending over a wide frequency from approximately zero frequency to a frequency
range without causing free oscillations to be pro
of several -thousand cycles wa's supplied to the
duced in the discharge path, i. e., the presence lamp, the intensity of the light supplied bythe
of the- metal capillary member results 1n stabiliz
glowing column was found to be independent
ing the frequency characteristic of the lamp. of frequency, and an oscillograph study ofthe
Again its use resulted in a better compromise as operation of the lamp failed to indicate the
to brightness, current range, operating voltage presence of oscillations inthe discharge path.
and extinction and breakdown voltages. An im
Life testswere made with a vseries of lamps .40
‘portant advantage of the use of a tapered capil
supplied with current of 20 mils and light cur
40
laryresides in the fact that the voltage required rent and voltage-current measurements were
to initiate a discharge vwithin the lamp is far be
made at stated intervals. These tests were made
low that required to effect this result in lamps, under identical operating conditions and indi
' I identical as to design and operating conditions,
cate that the variation of light with increase in 45A
but which are " provided with a straight-walled
life is small, and at the end of .-1500 hours, the capillary of the same diameter, i. e., the break- , lamps were still operating satisfactorily.
_ down voltage of the ,lamp is materially reduced.
An additional advantage of the type of con
` While the brightness of the illumination, sup
struction described above resides in the fact that
plied by lamps of the type described herein, for , the electrodes and concentrating member, being
a given value of current in the discharge path of'metal, may be accurately machined. Precision
50
between the electrodes, can be varied 'by chang
ing the pressure of the rare gas, this change af
'in the manufacture of these parts assures the
fects the extinction current, as well as the break- 55
down, operating and extinction voltages. It was
found by experiment that the best compromise
with a lamp of given _design is obtained by using
a charge of helium at approximately seven milli
meters of mercury in a lamp for recording pur
poses, and a charge of neon at approximately.
nine millimeters of .mercury in a lamp which is
used to illuminate a record or picture.
Theoperating characteristics of positive co1
umn glow discharge lamps of the type described
above was investigated by applying to its elec
trodes
a direct current potential of sufdcient value
65
tol maintain a discharge within the lamp and by
varying the current in steps between one mil andy
sixty mils. The intensity of the light supplied by
the lamp was found to vary substantially linearly ~ y
70
from-a minimum value to a value approximately
170 times that of the minimum value. 4These
comparative values were obtained by measuring
the direct current output of a potassium-hydride
photoelectric cell, the response curve of which is
u similar to that of process nlm when'it is illumi
5o.
production of lamps having substantially iden
tical operating characteristics, optical properties
and useful life.> Consequently, lamps of the type 55'
herein disclosed, and having these desirable char
acteristics, are readily reproducible.
l
Whilev certain specific details and dimensions
have been set forth above, it is to be understood
that the important features of the present inven 60
tion are >the use of a metallic member for con
centrating the positive column _glow discharge
and that a, tapering passage terminating in _a
capillary opening be used to effect the concen
tration. As to the details and dimensions of the 65
parts, as well- as the gas pressure to be used, this
will depend largely upon the operating condi
tions in any given case and the result to-be ac
complished.
‘
»
_
What isV claimed is:
70
1. A positive column glow discharge lamp com
prising cold electrodes, and, intermediate said
electrodes, a-metallic member having a tapered
passage terminating in a capillary opening.
2. A> positive column glow discharge lamp com- f
4
2,150,356
prising a Vcold cathode, a cold anode, and, inter
mediate said cathode and anode, a metallic mem
ber comprising a section surroundlngbut spaced
potential not substantially greater than that of
said anode.
5. A positive column glow discharge lamp com
from the cathode and having a conical extension ~ prising a vessel containing gas and enclosing
provi-ded with a tapered opening between said
section and said anode.
3. A positive column glow discharge lamp com
prising a vessel containing gas and enclosing
electrodes in the form of a cold anode and a cold
cathode, and a hollow metallic member in part
surrounding said cathode, the interior wall of
said part being cylindrical and symmetrically
spaced from the exterior surface of said cathode
with respect to the axis of said cylindrical wall,
said member being eñîectively extended into the
space between said cathode and anode and hav
ing its interior wall in this portion shaped to
form a conical channel coaxial with said cylin
drical wall with its larger end toward said cath
ode and its smaller end terminating in a capil
lary opening.
l
4. A positive column glow discharge lamp com
prising a vessel containing gas and enclosing
electrodes in the form of a cold anode and a
cold cathode, a hollow metallic member in part
surroundingV said cathode, the interior wall of
said part being cylindrical and symmetrically
spaced from the exterior surface of said cathode
with respect to the axis of said cylindrical wall,
30 said member beingl effectively extended into the
space between said cathode and anode and hav
ingv its interior wall in this portion shaped to
form a conical channel coaxial with said cylin
drical wall with its larger end toward said cath
35 ode and its smaller end terminating in a capillary
opening, and means for starting a glow’discharge
between said cold electrodes when the latter
are at operating potentials the difference of
which is below thestriking voltage comprising
40 means for temporarily bringing said member to a
electrodes in the form of a cold cylindrical cath
ode and a cold plate-like anode, the latter§hav-
5
ing a small opening therein in line with the axis
ofsaid cathode, and a hollow metallic member
in part surrounding said cathode, the interior
wall of said part being cylindrical and spaced a
unifom' distance from the cylindrical exterior
surface of said cathode, said ollow- metallic
member being effectively extende into the space
between said cathode and anode and having its
interior wall in this portion shaped to form a 15
conical channel concentric with said cathode and
aperture with its small end near and aligned with
said aperture in said anode and terminating in
an opening of a diameter at least as great as the
maximum dimension of said aperture'.
6. A positive column glow discharge lamp com 20
prising a vessel containing gas and enclosing
electrodes in the form of a cold cathode and a
cold anode and a metallic element forming a con
ical shaped channel between said electr'odes with
its larger end toward said cathode, said cathode
having an opening symmetrically positioned with
respect to said channel, the walls of said cathode
surrounding said opening and nearest said chan
nel being circular in shape in a plane perpendic 30
ular to the axis of said channel, the diameter
of said opening in said plane being not greatly
diiîerent than the diameter of the large end of
the channel.'
7. The combination as set forth in claim 6 in
which said cathode is in the form of a hollow 35
cylinder open at both ends and having its axis
coincide with that of said channel.
O'I‘TO C. BLEICHER.
40
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