Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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_CKGROUND OF T~E I~ENTION:
FIEID O~ r~
- The present invention relates to a no~el discharge lamp
in which a high pressure arc tu~e for high pressure discharge is electri-
cally cons~ected in parallel to a low pressure arc tube for low pressuredischarge and both arc tubes are placed in an outer bulb and a novel
lighting equipment which opera-tes the low pressure arc tube and the high
pressure arc tube with a high frequency ballast.
DESCRIPTION OF THF. PRIOR ARTS:
In general, a mercury pressure in a high pressure arc tube
is about several atm. during the operation of the discharge lamp in a high
pressure mercury vapor discharge lamp, a metal halide vapor dischar-
ge lamp and a high pressure sodium vapor lamp which have three to ten
times the luminous efficacy of an incandescent lamp. Therefore,
when the discharge lamp is once inactuated by a temporary power
voltage drop or a temporary service in-terruption, the discharge lamp
is not able to start immediately even though the power voltage is return-
ed to the normal level.
It has been difficult to s-tart the lamp lmtil the temperature in
the arc tube is lowered to decrease the mercury vapor pressure in the
arc tube to -the level required for the start. The time required for the
restart of the discharge is called the restart time which is about 3 to
5 minutes in the high pressure mercury vapor discharge lamp,
8 to 15 minutes in the metal halide vapor discharge lamp and 1 to 2
minutes in the high pressure sodium vapor discharge lamp which is
s-tarted with a ballast equipped with a high voltage pulse generator, and
2 to 10 minutes in the high pressure sodium vapor discharge lamp
q~
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which is started with a ballast having no high voltage pulse generator.
Thus, the high pressure discharge lamps which require a long restart
period are ncl~ s~isfactory, i~ their uses.
When a ~hïgh ~ressure discharge lamp having high efficacy
is consiclered to repl~ce for the iucandescent lamp which is main-
ly used as a light source but has a quite low efficacy, the disadvanta
geous long restart period should be considered.
.~ ballast is required for operating the high pressure clischarge
lamp, and it is large and heavy and accordingly, it is assembled sepa-
ra-tely from the discharge lamp. Therefore, it has been impossible to
consider the replacement of the incandescent lamp by a combination of
the ballast and the discharge lamp.
SU~RY OF THE INVENTION:
It is an object o-E the present invention to overcome the above-
mentioned disadvantages and to provide a discharge lamp which is
usually operated by a high pressure arc tube and also continues an
emission by a discharge caused by a low pressure arc tube during the
time from extinction to restart of the high pressure arc tube so as to
preven-t the extinction of the discharge lamp.
It is another object of the present invention to provide a light-
ing equipment which is compact and has high efficacy and can be used
the same as an incandescent lamp.
The foregoing and other objects of the present invention have
been attained by providing a discharge lamp which comprises a high
pressure arc tube for high pressure discharge and a low pressure arc
tube for low pressure discharge and an outer tube in which the high
pressure arc tube is electrically connected in parallel to the low pre-
ssure arc tube.
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~RIEF DESCRI TION OF THE DRAWINGS:
Fixl~res ~ ~nd 2 show one e~bodiment of the present invention
wherein Figure 1 is a front view of a discharge lamp; and Figure 2 is
a circuit diagram using the discharge lamp;
E'igures 3 and 4 show the other embodiment wherein Figure 3
is a front view of a lighting equipment and Figure 4 is a circuit diagram
using the lighting equipment.
DETAILED DE~CRIPTION OF T~E PREFERRED EMBODIMENTS:
Referring to Figures 1 and 2, one embodiment of the present
invention will be illus-trated.
In Figures 1 and 2, the reference numeral (1) designates an
outer bulb made of a light transmissable glass having an egg shape
which is equipped with a base (2) at one end; (3) designates a support
frame having parallel support wires (5),(5) which are held by each pla-te
].5 spring (4),(4) in the outer bulb and the support frame is connected toa stem lead (7) projected from the stem ~6) and is electrically connected
to the base (2). The reference numeral (8) designates a high pre-
ssure arc tube such as the 400 W metal halide vapor arc tube for high
pressure discharge which is held through a pair of support plates (9),(9)
2G to the support wire (5) of the support frame (3). A pair of electrodes(10),(11) are respectively provided at both ends in the sealed tube and
one electrode (lO) is electrically connected to the support frame (3),
and the other electrode (11) is electrically connected to the stem lead
(12) projected -from the stem (6) connected to the base (2).
The reference numeral (13) is a low pressure arc -tube for low pressure
discharge which i.s held through a pair of support pla-tes (14),(1~) to
the other support wire (5) of the support frame (3) and the low pressure
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arc tube has a pair of ele~tr~des ~15~,[16) at each end, and has an
inner diameter of 6 mm and a distance between the electrodes (15),(16)
of 20 mm and contains a mixed gas consisting of 99/O o~
neon and 1% ol argon under a pressure of 10 torr.
- One electrode (15) of the low pressure arc tube (13) is elect-
rically connected to the support frame (3) and the other electrode (16)
is electrically connected through an impedance elemen-t (17) such as a
resi.stor having 180 (~3 to the stem lead (12). That is, the series co-
nnection of the low pressure arc tube (13) and the impedance element
(17) is connected in parallel to the high pressure arc tube and these
elements are placed in the outer bulb (1).
As shown in Figure 2, the discharge lamp having said struc-
ture is connected through a ballast (18) to a power source (19).
When the power voltage is applied, the discharge of the high pressure
arc tube (8) starts and a current controlled by the bal.last (18) is fed
and the high pressure arc tube (8) is in the stable state about 5 minutes
after the discharge start. Sometimes, the discharge of the low pre-
ssure arc tube (13) simultaneously starts for a moment when the dischar-
ge of the high pressure arc tube (8) is star-ted. }lowever, an impedance
element (17) having a relatively high impedance such as 180 ~ (resistor)
is connected in series to the low pressure arc tube (13) so as to control
the current passing through the low pressure arc tube (13) to about
1 Amp. When the arc current having 5 to 6 Amp. is passed through
the high pressure arc tube in the starting period, the voltage between
the electrodes (10), (11) of the high pressure arc tube (8) is decreased
to 20 to 30 vol.t, and the voltage between the electrodes (15),(16) of the
low pressure arc tube (13) is decreased whereby the discharge of the
low pressure arc tube (13) is stopped and only discharge of the high
pressure arc tube (8) continues.
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In the stable state of the high pressure arc tube (8), a current
havi~g ~ o ~ . is passed throu$h the circuit of the base (2)- stem
lead ~l~)-electrode ~ -e~ectrode ~ support frame ~3)-stem lead
(7)-base (2) to -the ballast, however any current is not passed through
the circuit of the low pressure arc tube (13) and the impedance element
117) and the high pressure arc tube (8) maintains the stable state and
the low pressure arc tube (13) is kept in the non~discharge state.
When the high pressure arc tube (8) is extinguished from the
stable state by a temporary voltage d:rop of the power voltage, even
though the power voltage is returned to the normal level, the pressure
in the high pressure arc tube (8) is high as several atm. whereby the
discharge of the high pressure arc tube (8) is not capable of the start.
Thus, when the power voltage is applied to the high pressure arc tube
(8) in the state of incapable of the start, the low pressure arc tube (13)
is capable of the start. Therefore, the low pressure arc tube (13) is
immediately started when the high pressure arc tube (8) is extinguished.
The lighting is continued by the low pressure arc tube (13). Therefore,
the discharge lamp continues light emission corresponding to the light
emission character:istics of the low pressure arc tube (13) without
causing a complete inactuation of the discharge lamp. In this condition,
a current of 1 Amp. controlled by the impedance elemen-t (17) is passed
through the circuit of the base (2)-stem lead (12)-impedance element
(17)-electrode (16)-electrode (15)-support frame (3)-stem lead (7)-
base (2) to the ballast (18), whereas any current is not passed through
the high pressure arc tube (8).
When the temperature of the high pressure arc tube (8) is
decreased under the condition of the actuation of -the low pressure arc
tube (13), and the mercury vapor pressure in the arc tube is decreased
to be capable of -the start of the discharge, the discharge of the high
pressure arc tube (8) is started again and the stable state is given after
5 minutes and the light emission having desired elec-trical and optical
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characteristics is continued. In this e~m~lle, ~he time required for
the resta~ ~i the discha~e of the high pressure arc tube (8) is about
10 minutes. When tbe disc~arge of t~ne high pressure arc tube (8) is
started again, the discharge of the low pressure arc tube (13) is stopp-
ed because of the sar~e i:unctiorl at the start of the discharge lamp.
Therefore, the low pressure arc tube (13) is not actuated during the
actuation of the high pressure arc tube (8).
In said embodiment, the impedance element (17) is connected
in series to the low pressure arc tube (13). When the glow discharge
is continued in the state applying the power voltage to the low pressure
arc tube (13), it is possible to eliminate the impedance element (17)
only by the parallel connection of the low pressure arc tube (13) and
the high pressure arc tube (8).
In said emebodiment, 400 W metal halide arc tube is used as
the high pressure arc tube (8). Thus, it is not limited to use a 400 W
arc tube and it is possible to use arc tubes for high pressure mercury
vapor discharge lamps and high pressure sodium vapor discharge lamps,
etc. The arc -tube containing the mixed gas of neon and argon is used
as the low pressure arc tube. Thus, it is possible to use an arc tube
for low pressure mercury vapor discharge lamps, a fluorescent lamp
or a rare gas discharge lamp. The pressure of the sealed gas in the
low pressure arc tube (13) is preferably lower than 100 torr so as to
start the discharge by the normal voltage. Thus, these lamps can be
used.
In said embodiment, the resistor is used as the impedance
element (17) connected in series to the low pressure arc -tube (13).
Thus, it is possible to use a capacitor, a choke coil, a filament coil
or a combination of two or more of the capacitor, the choke coil,
and the filament coil or the resistor as the impedance element.
The impedance of the impedance element (17) can be select-
ed as desired depending upon the characteristic of the low pressure
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arc tube (13).
When a filament coil is used as the impedance element (17),
cer~ain light emission from the Eilament coil is given to make bright
dur:ing ~ ac~llati~ of the low pressure arc tube ~13) beEore the restart
of the high pressure arc tube (8~.
~ igures 3 and 4 show the other embodiment of the present
invention wherein the reference numeral (20) designates a lighting equip-
ment comprising a light transmiscible outer bulb (1), the high frequen-
cy ballast (18) and a base (2). In the outer bulb (1), a high
pressure arc tube (8), a tungsten filament (17) and a low pressure arc
tube (13) are placed. The high pressure arc tube (8) has electrodes
(10),(11) at each end, and one electrode (10) is connected to a support
lead (3) and the other electrode (11) is connected to a lead (12) of the
ballast (18). The support lead (3) is connected to the other
lead (7) oE the ballast (18). The low pressure arc tube (13) has elec-
trodes (15), (16) at each end, and one electrode 15 .is connected through the
tungs-ten filament (17) to the support lead (3) and the electrode (16) is
connected to the lead (12). Therefore, the low pressure arc tube (13)
connec-ted in series to the filament (17) is electrically connected in
parallel to the high pressure arc tube (8). The lead oE the
ballast (18) at the power source side is connected to the base (2).
The high pressure arc tube (8) can be a 30 ~ metal halide arc -tube
in which mercury, argon and scandium halide and sodiwD halide are
filled in the sealed condition. The low pressure arc tube (13) can be
a rare gas arc tube having an inner diameter of 5 mm and a distance
between the electrodes (15),(16) of 10 mm and contains a
mi~ed gas consisting of 99% of neon and 1% of argon under the pressure
of 20 torr. The impedance element can be a tungsten filament (17) hav-
ing 400 n for controlling the current in the low pressure arc tube (13) to
0.~ Amp. A inert gas is filled in the outer tube (1) so as -to prevent
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the ~Japorizati~n of tungsten from the filament and to prevent the oxida-
tion of Lhe el~e~s plac~ iD ~he o~ter hulb.
~he lighting ~e~iipment having said structure is connected to
the power source (19) as shown in Figure 4 whereby the high frequency
voltage generated by the high frequency ballast (1~) is applied
to the arc tube and the discharge of the high pressure arc tube (8) is
started to pass the current controlled by the ballast ~18) through
the high pressure arc tube (8).
The high pressure arc tube (8) reaches to the stable state
about 3 minutes after the start of the discharge. When the discharge
of the high pressure arc tube (8) is started, sometimes, the discharge
of the low pressure arc tube (13) is simultaneously started for a moment.
A filament having relatively high resistance of 400 Q is conne-
cted as the i.mpedance element (17) (resistor) to the low pressure arc
tube (13). 'rherefore, the current passing through the low pressure arc
tube is limited to 0.2 Amp. When the arc discharge current of 0.6 to
0.65 ~np. is passed through the high pressure arc tube at the start,
the vol.tage applied between the electrodes (10),(11) of the high pressure
arc tube (8) is decreased to about 20 Volt, and -the voltage applied bet-
ween the electrodes of the low pressure arc tube (13) is lowered to stop
the discharge in the low pressure arc tube (13) and only the high pre-
ssure arc tube (8) continues the discharge.
In the stable sta-te of the high pressure arc tube (8), the
current is passed through the circuit of the base (2)-ballast (18)-lead
(7)-support lead (3)-electrode (10)-electrode (11)-lead (12)-
ballast (18)-base (2) whereas any current is not passed through
the low pressure arc tube (13) and an impedance element (17) whereby
the high pressure arc tube (8) maintains the stable state whereas the
low pressure arc tube (13) continues the non-discharge state.
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~he~ the high pressure arc tube (8) is extinguished from the
sta'ble s~ate ~S~ ca te~pc,r~ry voltage drop of the po~er voltage, even
though ~he power ~ol~ge is -leturned to the normal level, the pressure
in the high pressure arc ~ube ~) is high as several atm. whereby the
discharge o~ the high pressure arc tube (8) i.s not capable oE -the start.
Thus, when the power voltage is applied to the high pressure arc tube
(8) in the state of incapable of the start, the low pressure arc tube (13)
is capable of -the start. Therefore, the 1.ow pressure arc tube 113) is
immediately star-ted when the high pressure arc tube (8) is extinguished.
The lighti.ng is continued by the low pressure arc tube (13) and the
tungsten ~ilament (17). Therefore, the discharge lamp continues light
emission corresponding to the light emission characteristics of the low
pressure arc tube (13) and the tungsten filament (l73 without caus-
ing a comple~e inactuation of the discharge lamp.
During the state, the high frequency current. of 0.2 Amp.
which is controlled by the filament (17) as the impedance element is
passed through the circuit of the base (2)-ballast (18)-lead (7)-
support lead (3)-filament (17) as the impedance e:lement-electrode (15)-
electrode (16)-lead (12)-ballast (18)-base (2) whereas any
current is passed through the high pressure arc tube (8).
When the temperature of the high pressure arc tube (8) is
decreased under the condition of the operation of the low pressure arc
tube (13) and the mercury vapor pressure in the arc tube is decreased
to be capable of the start of the discharge, the discharge of the high
pressure arc -tube (8) is started again and the stable state is given after
3 minutes, and the light emission having desired electrical and optical
characteristics is continued. In this example, the time required for
the restart of the discharge of the high pressure arc tube (8) is about
8 minutes. When the discharge of the high pressure arc tube (8) is
started again, the discharge of the low pressure arc tube (13) is stopp-
ed because of the same function at the start of the discharge lamp.
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Therefore, the low pressure arc tube (13) is not actuated during the
act~ation of the high pressure arc tube ~8).
The charac-teri~-ti~ oi the ~ighting equipment having the arc
tube ~:f-the 30 ~ ~t~ a.ide ~apor discharge lamp and the characteris
tics of lO0 W incandescent lamp are shown in Table 1.
As it is clear from the data of Table l, the lighting equipment
o-l this example of the present invention has three -times of the effic~acy
of the incandescent lamp and five times of the life of the incandescent
lamp.
The luminous efficacy in Table I means efficacy of only
the lamp as to-tal luminous flux/lamp power and the overall efficacy
means total efficacy of the lamp and the ballast as total luminous
flux/inpu-t power.
The 30 W metal halide vapor discharge lamp of -this embodi
ment is operated by the high frequency current having 20 KH~ and
accordingly, the loss caused by the ballast is smaller than
that of the conventional discharge lamp and the inpu-t power is 34 W.
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Table 1
._ _ _
Type ~ 100 W Light:ing equipment
incandescent lalr~p having 30 W metal halide
arc tube
_.___ __.___ _ __ , _
Power of lamp 100 30
(Watt)
~oltage of lamp _ 60
(Volt)
Current of lamp _ 0.56
(Amp.)
Total luminous flux 1520 1500
Luminous efficacy 15.2 50
_ _ _ ___
( lm ) __ __ _
I,i-fe (hr.) 1000 5000
In the embodiment shown in Figures 3 and 4, the tungsten
filament as the impedance element (17) is connected to the low pressure
arc tube (13). When the glow discharge is continued in the state apply-
ing the power voltage to the low pressure arc tube (13), it is possible
-to elimina-te the impedance element (17) only the parallel connection of
the low pressure arc tube (13) and the high pressure arc tube (8).
In said embodiment, 30 W metal halide arc tube is used as
the high pressure arc tube (8). Thus, it is not limited to use a 30 W
arc tube and it is possible to use arc tubes -for high pressure mercury
vapor discharge lamps and high pressure sodium vapor discharge lamps,
etc. The arc tube containing the mixed gas of neon and argon is used
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as the low pressure arc tube. Thus, it i~ possi~le to use an arc tube
Eor low pressure mercury vapor discharge lamps, a fluorescent lamp
or a rare gas discharge lamp.
The pressure of the sealed gas in the low pressure arc tube
(13)-is preferably lower than 100 torr so as to start the discharge by
the norma]. voltage. Thus, these lamps can be used.
ln said embodiment, the resistor is used as the impedance
element (17) connected in series to the low pressure arc tube (13).
Thus, it is possi.ble to use a capacitor, a choke coil, a filament coil,
or a combination of two or more of the capacitor, the choke coil, and
the filament coil or the resistor as the impedance element.
The impedance of the impedance element (17) can be select-
ed as desired depending upon the characteristic of the low pressure arc
tube (13).
~hen a filament coil is used as the impedance element (17),
certain light emission from the filament coil is givell to make hright
during the actua-tion of the low pressure arc tube (13) before the res-tart
of the high pressure arc tube (8).
In said embodiment shown in Figures 3 and ~1, the frequency
of the voltage and the current for the operating the arc tube (8) or (13)
by generating from the high frequency ballast (18) is 20 KHz.
Thus, it is preferable to use the frequency ranging from 1 K}lz to
100 KHz. When the frequency is less than 1 KHz, the compact and light
weight of the ballast are not satisfactory. When the frequency
is greater than 100 KHz, the extinction phenomenon caused by unstable
discharge in the xepeated starting of the high pressure arc tube (13) is
took p].ace, and this is serious disadvantage in the practical use.
In accordance with the present invention, the high pressure
arc tube for high pressure discharge is electrically connected in parall-
el to the low pressure arc tube for low pressure discharge and botharc tubes are placed in the outer bulb whereby the discharge lamp is
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usually opera~e~l by the high pressur~ ar~ -tube having high efficacy and
when the high ~-~e~ re arc tu~e is e~i.nguished by c~rt~in factor, the
low pressure arc tube i~ ~ctuated duri.ng the period ~rom the extinction
to the restart of the high pressure arc tube to prevent the complete
inactuation of the discharge lamp ancl to prevent complete darkness of
the lighting part. The discharge lamp having remarkable advantages
can be obtained.
~ en the high pressure arc tube for high pressure discharge
is electrical.ly connected in parallel -to the low pressure arc tube for
low pressure ~ischarge and both arc tubes are placed in the outer bulb
and are operated by the high frequency ballast having 1 ~Iz to
100 KHz, the discharge lamp is usually operated by the high pressure
arc tube having high efficacy and when the high pressure arc tube is
extinguished b~) certain factor, the low pressure arc tube is actuated
during the period from the extinction to the restart of the high pressure
arc tube to prevent the complete inac-tuation of the discharge lamp and
to prevent complete darkness of the lighting part. Moreover, the
ballast can be compact -to be capable of a combination arc tubes
and the ~allast as assembled :in one discharge lamp which can
be used to replace for the incandescent lamp in the lighti.ng equipment.
The lighting equipment having remarkab].e advantages can be obtained.
