Starting circuit design for initiating and maintaining arcs in vapor lamp

Guisinger, J. E.

English

NASA Technical Reports Server

REPLY TO 
ATTN OF: 
T 
NATIONAL AERONAUTICS AND SPACE AD 
WASIIINGTON, D C 20546 
October 15,  1970 
USI/Scientif i c  & TecA.nical Information Div is ion  
At ten t ion :  M i s s  Winnie M. Morgan 
FROM: GP/Office of A s s i s t a n t  General 
Counsel f o r  Pa ten t  Matters 
SUBJECT: Announcement of NASA-Owned 
U.S. Pa t en t s  i n  STAR 
I n  accordance w i t h  t h e  procedures contained i n  t h e  Code GP 
t o  Code U S 1  memorandum on t h i s  s u b j e c t ,  da ted  June 8, 1970,  
t h e  attached NASA-owned U.S. p a t e n t  i s  being forwarded f o r  
a b s t r a c t i n g  and announcement i n  NASA STAR., 
The fol lowing information i s  provided: 
U.S .  P a t e n t  No. 3,271,620 
Corporate Source : C a l i f .  I n s t i t u t e  of Technology 
Supplementary 
Corporate Source Jet  Propulsion Laboratory 
NASA Pa ten t  C a s e  NO.: ~~P-01058 
Please note  t h a t  t h i s  p a t e n t  covers an invent ion  made by an 
employee of a NASA c o n t r a c t o r ,  Pursuant  t o  Sec t ion  305(a) of 
t h e  Nat iona l  Aeronautics and Space A c t ,  the name of t h e  
Adminis t ra tor  of NASA appears on t h e  f i r s t  page of t h e  pa t en t :  
however, t h e  name of t h e  a c t u a l  inventor  (author)  appears  a t  
t h e  heading of Column No. 1 of t h e  S p e c i f i c a t i o n ,  fol lowing t h e  
words )I .  e e wi th  respect t o  an  inven t ion  o f ,  . ' I  
Enclosure:  
Copy of Pa ten t  
https://ntrs.nasa.gov/search.jsp?R=19710003065 2020-03-17T02:33:05+00:00Z
JAMES E. WEBB 
AND SPACE ~ ~ ~ ~ ~ ~ ~ T ~ ~ ~ I O ? ~  
INJSTRATOR OF THE NATIONAL AERON 
STARTING CIRCUIT FOR VAPOR I,Ah+PS AND THE LIKE - -  - - -  --....- - .... 
Filed O c t .  1, 1963 
3.271.620 
nautics 2nd Space Administmtian with respect to a n  
intention of Johia E. Goi4nger 
Filed Oct. 11, 1963, Ser. No. 313,136 
8 Claims. (Cl. 315-160) 
This invention relates generally to power supplies and 
more particularly to :i power supply suitable for starting 
and maintaining a high intensity vapor lamp. 
High intensity vapor lamp? generally require a very 
high volt:ige at low current for starting, an intermediate 
voltage at intcrrnediate currcnt just after starting, and a 
low volinge a t  high current for maintaining the lamp 
encrgiied after a plasma arc i4 established therein. Al- 
tho.lgh arcs can he established in vapor lamps by the 
app1ic:ition thcrcacross of a sufficiently high direct cur- 
rent voltage, it has been faund that a lower starting volt- 
age can be tolerated if a high frequency alternating cur- 
rent volicige is utilized instead of a low frequency alter- 
nating current voltage or a direct current voltage. 
Although various power supplies are disclosed in the 
prior art for starting and maintaining high intensity vapor 
lamps, none of them is entirely satisfactory. Most prior 
art power supplies utilized with vapor lamps employ trans- 
formers thereby making them somewhat heavy, slow act- 
ing, and expensive. 
In view of the deficiencies in prior art vapor lamp 
power supplies, it is the principal object of the present 
invcntion to provide an improved power supply suitable 
for starting and mainiaining an arc in a vapor lamp. 
Briefly, the invention herein is based on the recognition 
that an oscillator can be formed by connecting a feedback 
path, comprised of a load, e.&. a vapor lamp, and an ap- 
propriate length of transmission line, between the out- 
put terminal and control input terminals of an amplifier 
so that oscillations will occur so long as the load com- 
priqes a substantially open circuit. By positioning the 
load in the transmission line a t  a point of maximum 
voltage and minimum current, ideal starting conditions 
for a vapor lamp are established. In response to a short 
circuit condition being developed across the load, ap- 
propriate switch means can be actuated to apply a low 
direct current voltage maintenance supply thereto to re- 
move the higher direct current voltage supplied to the 
amplifier. 
The novel features that are considered characteristic of 
this invention are set forth with particularity in the ap- 
pewled claims. The invention itself both as to its or- 
ganiiation and method of operation, as well as additional 
objects and advantages thereof, will best be understood 
from the following description when read in connection 
with the accompanying drawings, in which: 
FIGURE 1 is a block diagram of a power supply con- 
structed in accordance with the present invention; and 
FIGURE 2 is a schematic diagram of a preferred em- 
bodiment of a vapor lamp starting circuit constructed 
in accordance with the present invention. 
Attention is initially called to FIGURE 1 of the draw- 
ings which illustrates an amplifier IO having a control 
input terminal 12 and an output terminal 14. A high 
voltage direct current source 16 is connected through a 
switch 18 to the amplifier 10. As is well known, virtual- 
ly any amplifier can be connected in a circuit arrange- 
ment so as to cause it  to oscillate by coupling a portion 
of the output voltage derived from the amplifier back into 
the control input terminal of the amplifier. Generally, 
such oscillator feedback paths arc comprised of resonant 
circuits including capacitors and inductive elements. In 
accordance with the present invention, in lieu of providing 
such a feedback path, a transmission line coniprised Of 
parallel conductors I8 and 20, respectively connected to 
the control input terminal 82 and output terminal 
B pi ovided. The conductors I8 and 20 arc teiminaled in a 
load 22. 
The load 22 can comprise, e.g. a vapor lamp, char- 
acteristically defining an open circuit condition prior 10 
the ionization of the vapor therein. The vapor can be 
10 ionized by applying a high direct ourrent voltage aci.055 
the lamp elcctrorle~ or a not quite so high voltage alter- 
nating at a high rrequency, preferably in the radio fre- 
quency range. Once the vapor is ionized, an arc is 
established thereby effectively creating a virtually no re- 
The 
arc, once established, can be maintained by a much lower 
direct current voltage than is required to initiate it. Con- 
sequcnlly, a low voltagc direct current 5ource 24 is pro- 
vided. A switch 26 couples the low volt:igc direct cur- 
Means (not shown in 
FIGURE 1 )  responsive to the cslablishment of a short 
circuit in load 22, can be provided for opening the 
switch 18 and closing the switch 26. By appropriately 
determining the transmission line length, a high volkge 
25 low currcnt condition can be established across the load 
22 to thereby assure most rapid starting. The load 22 
will be positioned a t  the point of maximum voltage and 
minimum current by placing it substantially one quarter 
wavelength from a point of maximum current and mini- 
Attention is now called to the preferred embodiment 
of the invention illustrated in FIGURE 2. The amplifier 
in FIGURE 2 comprises a pentode including a cathodc 
30, a control grid 32, a scrcen grid 34, a suppressor grid 
35 36, and an anode 38. The cathode 38 is connected 
through a push button switch 4Q and a resistive imped- 
ance 42 to the negative terminal of a high voltage direct 
current source 411. The source 44 is referenced to ground. 
The first end of a first conductor 46, of a pair of parallcl 
40 conductors comprising a transmission line is connected 
to the junction betwecn cathotlc 30 and the push button 
switch 40. The control grid 32 is connccted to an inter- 
mediate point on the first conductor 46 spaced from the 
first end thereof by a distance M. The  anode 38 is con- 
45 nected to an intermediate point on the second conductor 
48 spaced a distance N from the first cnd thereof which 
is referenced to ground. A capacitor 50 is connected 
between the first ends of the conductors 46 and 48. A 
vapor lamp 52 is connected between the second ends of 
50 the conductors 46 and 48. The length of each of the 
conductors 46 and -28 is represented by the distance L. 
As is usual practice, the suppressor grid 36 is connected 
to the cathode 30. The screen grid 34 is connected to 
the cathode of a diode 54 whose anode is connected to 
65 the first end of the conductor 46. The cathode of the 
diode 54 is in addition connccted to  a negative terminal 
of a low voltage direct current source 56 which is refer- 
enced to  ground. 
The transmission line conductors 46 and 48 together 
60 with the lamp 52 act as a tank circuit for the pentode. 
The length L of each of the conductors 46 and 48 is equal 
to substantially one quarter wavelength of the oscilla- 
tions provided by the oscillator comprised of the pentode 
and the quarter wave line, the frequency of oscillations 
05 being determined primarily by the quarter wave line. 
Pn response to the actuation of the push button switch 40, 
the high voltage direct current source 44 is applied across 
the cathode 30 and anode 38 of the pentode. The open 
circuit of the lamp 52 appears as a very high impedance 
70 load with some capacity bctween conductors 46 and 48. 
The impedance however is not so great as to prevent 
18 sistance or short circuit path between the electrodes. 
20 rent source 24 to the load 22. 
30 mum voltage. 
3,B71,620 
oscillation buildup in the quarter wave line during a efficient use is made of energy provided by the 
short initial period, e.g. a few microseconds, or until the source 56. 
high frequency oscillations are of sufficient magnitude to Although the invention has been illustrated in its pre- 
ionize the lamp vapor. The distance M along conduc- ferred embodiment comprising a vapor lamp starting 
tor 46, provides sufficient alternating current feedback 5 circuit, it is specifically pointed out that loads other than 
voltage to maintain oscillations. The distance N along a vapor lamp, which have substantially the same starting 
conductor 48 is provided to match the impedance of the and maintaining characteristics, can be utilized in lieu 
pentode to the impedance of the transmission line. of the lamp and other amplifiers can of course be sub- 
Inasmuch as the oscillations occur at a high frequcncy, stituted for the pentode. ft is also suggested that the in- 
preferably in the radio frequency range, the capacitor 50 10 vention finds utility in situations wherc it is unnecessary 
will serve to effectively short circuit the high frequency to maintain n current through thc load, as for examplc 
voltage vnriations across the first ends of the conductors i n  photo flash unit5 wherc it is merely desired to excite, 
46 and 48 and thereby establish a low voltage high cur- but not tn,iin[ain, the load. In such a situation, the diode 
rent condition across these first ends. Since thc leni<th 54 and sotircc 56 can be deleled and as a consequence in 
of thc conductors 46 and 48 is equal to substantially one 16 response to the actuation of the push button 40, oscilla- 
quarter wavelength of the oscillations, an opposite condi- tions will be initiated in the pentode which will in turn 
tion, i.e. a high voltage low current condition will be ionize the vapor within the lamp 54 which in turn will 
cstabli5hed at the second ends of the conductors 46 and quench the oscillations. Thc temporary ionization how- 
48, adjacent the lamp 52. This condition adjacent the cver can be utilized for, e&, photo Aash applications. 
lamp 52 is, of course, an ideal condition to initiate 20 It is further pointed out thal an embodiment of the 
ionization of the vapor in the lamp 52. As the ionization invention is particularly useful for starting devices that 
increases, the impedance of the lamp 52, of course, drops, are to be maintained in operation by low voltage transis- 
finally becoming so low that oscillations in the pentode tor regulated power supplies where it is very necessary 
stop because the tank circuit is effectively short circuited. to prevent any high voltage from appearing across the 
As the impedance of the lamp 52 drops, direct current 25 power supply output terminals. 
from the source 44 flows through the lamp 52, and this What is claimed is: 
direct current increases until a plasma arc is formed with- 8. In combination with a load defining a substantially 
in the lamp 52 a t  which time the lamp substantially ap- open circuit condition prior to the application of e high 
pears as a short circuit. voltage high frequency signal thereacross and a substan- 
Prior to the establishment of the plasma arc within 30 tially short circuit condition subsequent to the applica- 
the lamp 52, the direct current flow through the imped- tion of said high voltage high frequency signal there- 
ance 42 was small and consequently the voltage on the across, an oscillator for generating said high voltage high 
anode of the diode 54 was substantially at the high nega- frequency signal, said oscillator comprising an amplifier 
tive voltage established at the negative terminal of source having an output terminal, a control input terminal; and 
44. Consequently, the diode 54 was back biased. In 35 a transmission line terminated by said load connected 
response however to the increased direct current flow between said output terminal and said control input ter- 
through the impedance 42 resulting in a greater voltage minal, and means rcsponsivc to the establishment of said 
drop thereacross, the voltage on the anode of the diode substantially short circuit condition for maintaining said 
54 changes significantly to thereby forward bias the diode load in that condition. 
54. Consequently, a maintaining current path is estab- 40 2. The combination of claim 1 including a high volt- 
lished from ground, through uctor 48, through age direct current source; a low voltage direct current 
the lamp 52, through the cond through the diode source; first switch means connecting said high voltage 
54, through the low voltage urrent source 56, direct current source to said amplifier; second switch 
to  ground. means connecting said low voltage direct current source 
In normal operation, an operator would maintain the 45 across said load; and means for opening said first switch 
push button switch 40 closed until he notices a sudden means and closing said second switch means in response 
increase in lamp brightness which indicates to the opera- to said short circuit condition being defined. 
tor that a plasma are has been established in the lamp 53 3. The combination of claim 11 wherein the length of 
and that the lamp 52 can thereafter be maintained by said transmission line is equal to  one quarter wavelength 
the low voltage source 56. In response to  this sudden 50 of said high voItage high frequency signal. 
increase in lamp brightness, the operator can then release 4. The combination of claim 3 including menns for 
the push button switch 40. The low voltage source 56 establishing a low voltage high current condition at  a 
can be made to provide a humming sound when it is first end of said transmission line remote from said load 
supplying current to thereby advise the operator that the and a high voltage low current condition at a second 
push button switch 4 can be released. Alternatively, a 55 end of said transmission line adjacent said load. 
current monitoring device e.&. an ammeter may be pro- 5. A circuit for establishing an arc in a vapor lamp 
vided in the low voltage source 56 to indicate when it is comprising an amplifier including an output terminal and 
supplying current to thereby advise the operator that the a control input terminal; a high voltage direct current 
push button switch 40 can be released. Further, in a source; first switch means coupling said high voltage di- 
more expensive circuit arrangement, the push button O0 rect current source to said amplifier; first and second 
switch 40 can be automatically opened by some relay parallel conductors; means connecting said vapor lamp 
arrangement or  through the utilization of a diode switch- between first ends of said first and second conductors for 
ing circuit similar to that utilized for diode 54. generating an oscillating signal in said conductors; means 
is back biased, the negative voltage respectively connecting said output and control input ter- 
a t  the cathode 30 of the pentode is far below that of the 05. minals to said first and second conductors; means con- 
screen 34 and considerable current thereby flows through necting a capacitor between said first and second con- 
the pentode. However, once the diode 54 is forward ductors spaced from said lamp by a distance substantially 
biased the only voltage drop between the screen 34 and equal to one quarter of the wavelength of said oscillating 
the cathode 30 is the forward voltage drop across the signal whereby a low voltage high current condition will 
diode 54, which of course is very small thereby permitting 70 be established across said capacitor and a high voltage 
only a negligible current flow through the pentode. Since low current condition will be established across said lamp 
almost all of the current from the low voltage source 56 for thereby establishing an arc in said lamp. 
thereby flows through the lamp and since there i s  n o  6. The circuit of claim 5 wherein said amplifier com- 
impedance connected in series with the sou'rce 56, except prises a vacuum tube having a cathode, a control grid, and 
for the forward resistance of the diode 54, extremely 7s anode; means connectiog said high voltage direct current 
3,271,620 
source in series with an impedance and sai& first switch 
means across said anode and cathode; and means con- 
necting said lamp between said anode and said control 
grid. 
7. The circuit of claim 5 including a low voltage di- 
rect current source; second switch means coupling said 
low voltage direct current source across said lamp, and 
means rcsponsive to the establishment of said arc for 
closing said second switch mcans. 
8. The circuit of claim 7 whcrein said amplifier corn- 
priscs B vacuum tube having a cathode, a control grid, 
and an anode; means connecting said high voltage direct 
current source in scrics with an irnpedancc and said first 
switch means across said anode and cathode; incans 
connecting said lamp between said anode and said control 
6 
grid; and wherein said second switch means comprises a 
diode connected between said low voltage direct current 
source and said impedance. 
References Cited by the Examiner 
UNITED STATES PATENTS 
2,499,155 2/1950 O’Neil _ _ _ _ _ _ _ _ _ _ _ _  331-99 X 
2,599,945 6/1972 Schmitt _ _ _ _ _ _ _ _ _ _ _  331-99 X 
FOREIGN PATENTS 
5 
10 
774,474 5 /  1957 Great Britain. 
JOHN W. HUCKERT, Prhaty Examiner. 
A. M. LESNIAIC, Assistant Exaiiiiiier. 
lis 


Starting Circuit for Vapor Lamps and the Like-Patent

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server