close

Вход

Забыли?

вход по аккаунту

?

Патент USA US3080510

код для вставки
March 5, 1963
P. HOEKSTRA
- 3,080,502
GAS DISCHARGE FLASH LAMP CIRCUIT
Filed Sept. 3. 1959
15
n
285L215? §§~24
7
i‘
z”
3
2
+
+
16
5
5.15
L
C
INVENTOR
PIET HOEKSTRA
BY
‘f
AGEN
r
assassz
Patented Mar. 5, 1953
2
3,080,562
GAS DISCHARGE FLASH LAMP CIRCUIT
Piet Hoekstra, Ernntasingel, Eindhoven, Netherlands, as
signor to North American Philips Company, Inc, New
York, N.Y., a corporation of Delaware
Filed Sept. 3, 1959, Ser. No. 837,831
Claims priority, application Netherlands Sept. 25, 1958
5 Claims. ((11. 315-476)
From the above-mentioned US. patent it is known
that aforesaid interruption of the current in the normal
operating condition sometimes does not occur owing to
the relay valve remaining conductive after the termina
tion of the ?ashing period, which gives rise to an ab
normal operating condition in which a continuous cur
rent is maintained and the effect of the use of the light
?ashes is lost.
The disadvantages brought about by this abnormal
The invention relates to a device known from US. 10 operational condition are avodied in a device according to
the said U.S. patent by including in the circuit of the
relay valve and the light source a relay switch, whic
?lled, arti?cially cooled high-pressure discharge lamp,
can be switched on and off by a controllable recti?er
with the aid of a control-voltage, obtained from an
which is energized by pulses via controlled, gas- or
vapour-?lled relay valve in order to obtain light ?ashes. 15 impedance included in the circuit and having such an ef
feet on the recti?er, after the device has been switched on,
Such a device may be employed, for instance, in a pic
in the normal operating condition in which the relay valve
ture ?lm projector, in which the projector lamp emits
Patent No. 2,829,315, issued April 1, 1958, comprising
an electric light source in the form of gas- or vapour
one or more light ?ashes per ?lm picture. The relay
is periodically conductive, that the switch is closed,
Whereas in the case in which, after the termination of the
valve is controlled by means of electric pulses via the
grid so that it conveys current during the ?ashing period, 20 ?ashing period, the relay valve remains conductive, a
control-voltage is produced whereby the switch inter
whereafter in the normal operational conditions the cur
rupts the circuit.
rent is interrupted. The current pulses thus produced
According to a further aspect of the invention the
traverse also the projector lamp, which is thus caused to
last-mentioned device is employed in that the cut-off
emit light ?ashes. This process may be repeated with a
frequency determined by the frequency of the pulses. 25 vlotage and the positive ignition voltage are supplied
In’ accordance with the invention the discharge lamp is
to the said controllable recti?er, so that the latter is used
energized, in addition, by a direct-voltage source, so that
it is continuously traversed by a rest current.
Owing to the presence of the said rest current the
for two purposes.
The invention will be described more fully with refer
ence to the drawing.
lamp does not ignite again at each pulse, since the lamp 30 The FIGURE shows a device comprising a high-pres
remains ignited, be it invis-ibly.
sure mercury-vapour lamp 1, which is supplied, in order
This provides the advantage that the puls-atory supply
to obtain a plurality of light ?ashes, via a controlled, gas
?lled relay valve 2. The lamp 1 is cooled by means of
voltage for the lamp, controlled by the relay valve, may
be materially lower.
a water system, which is not shown in the FIGURE for
As stated above, it is common practice with such a
r the sake of simplicity. The device is energized by means
device to cool the high-pressure discharge lamp arti?cially,
of a direct-voltage source 3, which feeds a capacitor 5
via a resistor ‘i. This capacitor will be discharged
for example, with the aid of water. Since the relay valve,
supplying the discharge lamp, is not ignited during the
through the relay valve 2, the projector lamp 1 and the
starting period of the projector (about 2 sec.) the dis
coil 6, when the circuit thus formed is closed by the switch
40
charge lamp then does not produce ?ashes. The rest
13 and the relay valve 2 conveys current. At such a
discharge a damped LC-oscillation is produced, which
current, however, is switched on by starting the projec
tor motor. As soon as the latter and also the projector
produces a ?ash current in the projector lamp. Since
have reached the desired speed, the relay valve is ignited
during the next-following half period of the oscillation‘
the polarity of the voltage across the relay valve 2 is
periodically. It has been found, however, that, if the
starting period is too long, the rest cur-rent (of for ex 45 different, this valve will be non-conductive and thus pre
ample 0.1 to 0.5 A.) already switched on produces
vent further oscillations. This process may be repeated,
such a high temperature of the tungsten electrode that it
since after some time, the relay valve again becomes
is volatilized, so that a black deposit is produced on the
conductive by a pulse at the grid 7, so that the capacitor 5,
wall of the lamp.
which has been recharged in the meantime, can again pro
This disadvantage is obviated in accordance with a
duce a damped LC-oscillation, which again gives rise
further aspect of the invention by providing the driving
to the emission of a single ?ash. In the normal opera
motor of the projector with a low-power generator, from
tional conditions the relay valve must convey current only
which a positive voltage can be obtained, which is sup
during the ?ashing periods, whereas beyond these periods
plied to the control-circuit of an adjustable recti?er,
no current must be passed.
55
which, however, remains blocked during the start of the
As stated above, there is a risk of a continuous pas
motor by a negative control~voltage and which serves to
sage of current through the relay valve 2 after the cir~
energize a relay, the contacts of which interrupt the cir
cuit has been closed. In this case the capacitor 5 is no
cui-t of the rest cur-rent and the pulse during the start.
longer charged in addition and the lamp 1 will be directly
When the projector motor has attained its full speed of
energized from the source 3 via the relay valve 2. This
revolution, the positive voltage derived therefrom is so 60 condition is stable, since the damped LC-oscillation is
high that it compensates the negative cu-t-o? voltage to an
lacking and there is no cause for the relay valve 2 to be
extent such that the recti?er ignites and the contacts are
blocked. The circuit of the valve 2 and the lamp 1 in
closed.
cludes a mechanical switch 13, which can be switched
A further aspect of the invention consists in that the
on and o? by a control-voltage, which is derived from a
voltage of the generator is supplied, in the form of syn 65 resistor 9 in the circuit, which resistor is connected in
chronized ignition pulses (for instance by means of the
series with the lamp 1. The relay 8 is energized from the
“striking pin” of the Maltese cross of the projector) to
alternating current supply voltage via a transformer 12
the relay valve. During the start the voltage of these
via a controlled recti?er, which comprises two gas-?lled
ignition pulses is not yet su?iciently high to ignite the
70 tubes 10 and 11, whilst the control via the interconnected
relay valve, which may give rise to the aforesaid black
grids is obtained by the control-voltage from the resistor
ening of the wall of the lamp.
9. The supply circuit of the relay ‘8 includes, moreover,
3,080,602
3
tional conditions are maintained.
4
the electric pulses supplied to said lamp to actuate said
switch means thereby to interrupt the application of said
direct voltage to said lamp.
a mechanical switch 14. The relay is arranged so that,
when the switch 14 is closed, a relay current is'produced,
which is capable of attracting the switch 13, so that the
circuit is closed. If a pulse at the grid 7 produces a
current pulse, a pulsatory control-voltage will be pro-.
duced in the normal operational conditions, in which the
?ashes are of very short duration, the said voltages pro
ducing only such a reduction in the mean relay current
that the switch 13 remains closed and the normal opera
2. A device comprising a light source in the form of
a gaseous discharge lamp, circuit means for supplying
electric pulses to said lamp thereby to intermittently en
ergize the same at a high intensity value,- mean for addi
tionally supplying a direct voltage to said lamp thereby
to continuously energize said lamp- at a low intensity
The reduction is due 10 level, switch means interposed between said lamp and said
to the fact that during the ‘flashing period the tubes 10' and.
1-1 are cut all by the control-voltage, so that during this
time the relay is not fed, which ‘does not a?'ect the total
mean time owing to the arrangement of the relay and toy
theshort duration. However, if in the ‘abnormal opera~ 15
pulse and direct voltage supply means, means for actuat
ing said intermittent energizing means, and means for
closing said switch. means after a given interval follow
ing theinitiation of the operation of said actuating means.
tional conditions an abnormal current occurs owing to
3. A device comprising a light source in the form of
a gaseous discharge lamp, circuit means for supplying
the relay valve remaining conductive, the resultant con
electric pulses to said lamp thereby to intermittently ener
trol-voltage will give rise to such a reduction in the mean
relay current that the switch 13 is released and inter
gize the same at a high intensity value, means for addi
cally switched on, which source supplies the rest cur 30
4. A device comprising a light source in the form of
a gaseous discharge lamp, circuit means for supplying
tionally supplying a direct voltage to said lamp thereby
rupts the circuit. Thus the control-voltage is suppressed. 20 to continuously energize said lamp at a low intensity level,
switch means interposed between said lamp and said pulse
‘and the switch 13 is re-attracted, so that the ?ashing proc-.
and direct voltage supplymeans, means for actuating said
ess can restart. This may be repeated until the normal
intermittent energizing means, and‘ means for closing said
operational conditions are reestablished. This process
switch means after a given interval following the initiation
has so short a duration that it has no appreciable e?ect
on the quality of the ?lm projection, if the light source 25 of the operation of said actuating, means, said closing
means comprising an electron discharge system for ener~
is employed ‘as a projector lamp in a ?lm reproducing
gizing said switch means, means for biasing said discharge
apparatus.
system in a deenergizing condition, and mean responsive,
When the projector motor 15 is switched on by closing
to said actuating means for overriding said biasing means.
the switch 14, the direct voltage source 16 is automati
rent for the lamp 1; the lamp 1 is cooled by connectingit'
electric pulses to said lamp thereby to intermittently
energize the same at a high intensity value, comprising.
a- gaseous discharge relay valve, means for additionally
generator 17 is provided, which supplies pulses for the 35 supplying a direct voltage to said lamp thereby to con
tinuously energize said lamp at a low intensity level,’
ignition of the relay valve 2 via the transformer 18.
switch means interposed between said lamp and said‘
The recti?ers 10 and 11 include screen grids 19 and 20,
pulse and direct. voltage supply means, means ?or actu
to which an alternating voltage from the winding 21 is
ating. said relay valve comprising a source of triggering
fed, this voltage being in phase opposition to the anode
voltage of the valves 10 and 11. The centre of the wind 40 pulses recurring at a given periodicity, said source being,
connected to said relay valve, and means for closing said‘
ing 21 is connected via the recti?er 22 to one. terminal
switch means after a given interval following the initi
of the generator 17, of which the other terminal is con
ation of the operation of said source of triggering pulses.
nected to the cathodes of the valves 10 and 11. A ca-.
5. A‘ device comprisingalight source in the form of
pacitor 23 and a resistor 24 serve as a smoothing device.
During the start of the motor 15, the voltage produced 45 a gaseous discharge lamp, circuit means for supplying
electric pulses to said lamp thereby to intermittently
by the generator 17, at-the transformer 18 is too lowv to
energize the same at a high intensity value, comprising
ignite the valve. Even ‘the positive bias voltage obtained
a gaseousydischarge relayvalve, means for additionally
by the recti?er 22 between thescreen grids 19 and 20
supplying a direct voltage to said lamp thereby to_con
and the cathodes of the valves 10 and 11, is too low to
with the water mains by well known means not shown.
The shaft of the motor 15 is coupled with the Maltese
cross of the projector. (not shown), on which a pulse
compensate the negative alternating voltage fromv the
winding‘21, so that the valves 10 and 11 remain cut off’
and the switch 13 remains open. Therefore norest cur?
50
tinuously energize said lamp at allow intensity level,
switch, meansinterposed' between said lamp‘ and‘ said;
pulse and direct voltage supply means, means for actu
adting said relay valve comprising a source of triggering
pulses recurringat a given periodicity, said source beingv
full speed of revolution, the voltage of'the generator 17. 55 connected to said relay valve and means'for closing said'
switch means after a given interval following the initi
increases so that the valves 10 and llbecorne conductive
ation, of operation of said source of triggering pulses,
and the switch 13 is thus closed, after which the relayv
said closing means comprising an electron discharge sys
valve 2 also becomes conductive and the ?rst light ?ash
tem ?or energizing said switch means, means for biasing
is produced in the lamp. Thus blackening of the lamp is.
said discharge system in a deenergizing condition, and
avoided.
means responsive to said actuating means for overriding
What is claimed is:
said biasing means.
1. A device comprising a light source in the form of a
gaseous discharge lamp, circuit means for supplying elec
References Cited inthe'?le of this patent
tric pulses to said lamp thereby to intermittently energize
the same at a high intensity value, means for additionally
_
UNITED STATES PATENTS
supplying a direct voltage to said lamp .thereby'to en'-.
1,908,191
Schriever _____________ .... May 9, 1933
ergize said lamp at a low intensity level, switch means-i11
2,178,423
Inman ______________ __.Oct. 31, 1939
terposed between said lamp and said direct voltage sup-.
2;385,397
Blackburn __________ __ Sept. 25, 1945'
ply, and control means responsive to the interruption of ‘ 70 2,829,315
Hoekstra _,_____g _____ -_ Apr. 1, 1958'v
rent?ows from the voltage source 16 through the lamp’ 1.
As soon as the motor 15 has’ substantially attained ,the
Документ
Категория
Без категории
Просмотров
0
Размер файла
411 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа