CA1114889A - Electronic starter for igniting a discharge lamp - Google Patents
Electronic starter for igniting a discharge lampInfo
- Publication number
- CA1114889A CA1114889A CA295,704A CA295704A CA1114889A CA 1114889 A CA1114889 A CA 1114889A CA 295704 A CA295704 A CA 295704A CA 1114889 A CA1114889 A CA 1114889A
- Authority
- CA
- Canada
- Prior art keywords
- starter
- resistor
- temperature
- transistor
- semiconductor device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/02—Details
- H05B41/04—Starting switches
- H05B41/042—Starting switches using semiconductor devices
- H05B41/044—Starting switches using semiconductor devices for lamp provided with pre-heating electrodes
- H05B41/046—Starting switches using semiconductor devices for lamp provided with pre-heating electrodes using controlled semiconductor devices
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/54—Igniting arrangements, e.g. promoting ionisation for starting
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J7/00—Details not provided for in the preceding groups and common to two or more basic types of discharge tubes or lamps
- H01J7/30—Igniting arrangements
Abstract
ABSTRACT
An electronic starter for igniting a discharge lamp, the starter having two input terminals interconnected by an elec-tric circuit which includes a controlled semiconductor switch and a control circuit for controlling this semiconductor switch. The control circuit contains a temperature-sensitive circuit element which inhibits at an elevated temperature the igniting function of the starter with the control circuit for the controlled semi-conductor switch comprising an auxiliary switch connected to the temperature-sensitive circuit element. The auxiliary switch is controlled by a threshold voltage element and is open if the voltage across the threshold voltage element is lower than its threshold voltage.
An electronic starter for igniting a discharge lamp, the starter having two input terminals interconnected by an elec-tric circuit which includes a controlled semiconductor switch and a control circuit for controlling this semiconductor switch. The control circuit contains a temperature-sensitive circuit element which inhibits at an elevated temperature the igniting function of the starter with the control circuit for the controlled semi-conductor switch comprising an auxiliary switch connected to the temperature-sensitive circuit element. The auxiliary switch is controlled by a threshold voltage element and is open if the voltage across the threshold voltage element is lower than its threshold voltage.
Description
~ .
The invention relates to an electronic starter for igniting a discharge lamp, the starter having two input terminals which are interconnected by an electric circuit comprising at least a controlled semiconductor switch, the starter furthermore comprising a control circuit for controlling said semiconductor switch, this control circuit comprising a temperature-sensitive circuit element which inhibits the igniting function of the starter at elevated t~mperatures. The invention also relates to an electric circuit comprising a gas and/or vapour discharge lamp as well as an electronic starter of the type mentioned in the preamble, which starter is used for igniting that lamp.
It may happen that a discharge lamp refuses to ignite, for example owing to ageing. Such a situation should not result in an excessive electric current in the stabilisation ballast arranged in series with the lamp because this might damage that ballast or might even cause a fire.
It is therefore desirable to inhibit the operation of the starter if the relevant lamp does not ignite a few seconds after the circuit has been energized.
French Patent Application No. 2,279,302 -M. Remery - published February 13, 1976 described a lamp circuit comprising an electronic starter
The invention relates to an electronic starter for igniting a discharge lamp, the starter having two input terminals which are interconnected by an electric circuit comprising at least a controlled semiconductor switch, the starter furthermore comprising a control circuit for controlling said semiconductor switch, this control circuit comprising a temperature-sensitive circuit element which inhibits the igniting function of the starter at elevated t~mperatures. The invention also relates to an electric circuit comprising a gas and/or vapour discharge lamp as well as an electronic starter of the type mentioned in the preamble, which starter is used for igniting that lamp.
It may happen that a discharge lamp refuses to ignite, for example owing to ageing. Such a situation should not result in an excessive electric current in the stabilisation ballast arranged in series with the lamp because this might damage that ballast or might even cause a fire.
It is therefore desirable to inhibit the operation of the starter if the relevant lamp does not ignite a few seconds after the circuit has been energized.
French Patent Application No. 2,279,302 -M. Remery - published February 13, 1976 described a lamp circuit comprising an electronic starter
- 2 -!
~MF.77-505 20.12.77 of the type mentioned in the preamble, wherein the above-mentioned protection is obtained by m~ans of a resistor having a negative tempera-ture coefficient (NTC).
In an embodiment of that; ~rench Patent Application this resistor is arranged in parallel with a capaci-tor which is part of the control aircuit of the semiconductor switch of the starter.
A drawbac~ of that prior art electronic starter is that, in the operating condition of the lamp, an electric current flows continuously through the NTC resistor~ so that it is difficult, and sometimes even impossible, - after a brief interruption of the power supply malns, - to ignite the lamp again after it has extinguished.
A second drawback of the above-mentioned prior art electronic starter is that an accidental interruption of the NTC resistors puts the pro-tection of the ballast out of operation in the case of a lamp which fails to ignite.
It is an object of the invention to provide :^ an electronic starter of the type mentioned in the preamble by means of which the discharge lamp to be ignited by it can rapidly re-ignite even after a short ` interruption of the mains voltage.
In addition it is an object of the invention to provide certain classes of electronic starters of the _3_ ,-:
PHF.77-505 20.12.77 type mentioned in the preamble, which do not only obviate the ~irst-mentioned drawback but also the second drawback. That is to say that in that case certain defects in the temperature-sensitiVé circuit c~mponent do not result :in damage to the lighting device to which said starter is connected. This means here that an interruption in the temperature-sensitive circuit component or an accidental short-circuit o~
that temperature-sensitive circuit component of the starter may not rasult in an excessive electric current through the stabilisation ballast of the lamp.
An electronic starter according to the invention for igniting a discharge lamp, this starter having two input terminals which are interconnected by an electric circuit comprising at least a controlled semiconductor switch, the starter furthermore comprising a control circuit controlling said semiconductor switch, this control circuit comprising a temperature-sensitive circuit element which inhibits the igniting function of the starter at an elevated temperature, is characterized is that the control circuit of the controlled semi-conductor switch comprisies an auxiliary switch which is connected to the temperature-sensitive circult element, the auxiliary switch being controlled by a threshold voltage element, and the auxiliary switch being open if the voltage across the threshold voltage element is lower than its threshold voltage.
. -4-PHF.77 50 20.12.77 An advantage of this electronic starter is that, after a very brief interruption in the mains voltage, the Eelevant discharge-lamp after extinguishing -can again ignite reliably. This is the result of the ~act that the temperatu:re-sensitive circuit element carries no current in the opera-ting condition of the lamp.
The temperature of that temperature-sensitive circuit element can consequently be sufficiently low - after a very brief interrupt:ion in the mains voltage has ended to enable re-ignition of the lamp.
The threshold voltage component is preferably R zener diode. In addition, it is advantageous if the temperature-sensitive circuit element is thermally coupled to one of the starter components in which the - 15 current flows which passes through the stabilisation ballast. As a result thereof, that ballast current can be kept low in the case of a failing lamp.
With a further preferred embodiment of an electronic starter according to the invention a further resistor is present in parallel with the circuit which includes the semiconductor switch, and the temperature-sensitive circuit elemen-t is thermally coupled to that additional resistor. ~n advantage thereof is that the ballast current - in the case of a failing lamp - can also ~e kept low.
In the two last-mentioned embodiments the temperature-sensitive circuit element is not only _5_ ' P~IF.77-505 20.12.77 heated by the electric current ~lowing through the temperature-sensitive circuit element itself.
Electronie starters according to the present inventinn may reduce - in the case of a failing lamp -the ballast current to a harmlessly low value. This value need not be equal to zero. Owing to a suitable témperature increase of the temperature-sensitive circuit element whieh is present in the control circuit of the controlled semiconductor switch, it can be ensured that that con-trolled semiconductor switeh - which then carries the ballast current - is only occasionally condueting.
Then the ballast current assumes, after an ~nitial high value, a low final value.
Some embodiments of electronie starters aecording to the invention will now be deseribed with reference to the aecompanying drawings, in which:
Fig. 1 shows a first electric circuit comprising a diseharge lamp and an eleetronic starter according to the invention;
Fig. 2 shows an electric eircuit of a seeond eleetronie starter according to the invention;
Fig. 3 shows schematica~y the waveform of the electric voltage between the input terminals of the starter, plotted against time, in the circuits of Fig.1 and Fig. 2, if the discharge lamp does ~t immediately ignite, Fig. 4 shows schematically the waveform of the electric voltage between the input terminals of the ~6_ PHF.77-505 20.12.77 starter, plotted against time, in the circuits of Fig.1 and Fig.2, if a temperature-sensitive circuit element in that starter is defective;
Fig. 5 shows an electric circuit of a third electronic starter according to the invention;
Fig. 6 shows an electric circuit of a fourth electronic starter according to the invention;
Fig. 7 shows an electric circuit o~ a fifth electronic starter according to the invention;
.10 Fig. 8 shows an electric circuit of a sixth èlectronic starter according to the invention;
Fig. 9 shows a cross-section through a portion of the electronic starter of Fig. 5; and Fig. 10 shows a variant of the cross-section of Fig. ~ of an electronic starter.
In Fig. 1 references 1 and 2 denote preheatable electrodes of a low-pressure mercury vapour discharge lamp 3. The electrode 1 is connected to a terminal 4.
The electrode 2 is connected to a terminal 5 of an a.c~ voltage mains supply of, for example, 220 volts, 50 Hz.
Connected to the terminal 4 there is a stabi-lisation ballast which is either inductive (ballast 6) or consists of a series arrangement of an electric coil and a capacitor, which series arrangement (ballast 7) is capacitive at the above-mentioned mains frequency.
The other end o~ the relevant ballast is connacted to a terminal 8 ~hich is connected to a second terminal 9 of the a.o. voltage mains.
i -7 .
PHF~77~5o5 20.12.77 The two ends of the electrodes 1 and 2 of the lamp 3 remote from the supply mains are connected to input terminals IO and 11 respectively of an electronic starter 12. The starter 12 serves for igrliting the lamp 3.
A diode bridge .13 to 16 inclusive is connected to -the terminals 10 and 11. In addition, the terminals 10 and 11 are interconnected via a capacitor 17 and a teMperature~
. sensitive auxiliary resistor 18.
. The interconnected anodes of the diodes 11~
10- and 16 are connected to a common conductor 19 (negative conductor).
A conductor 20 (positive conductor) is connected via a series arrangement of two resistors 22 and 21 to the terminal 10. The resistor 21 is shunted by a resistor 23 having a negative temperature coefficient. The conductor 20 is connected to the terminal 11 via a resistor 24.
Via an inductance 26 the anode of a thyristor 25 is.connected to the interconnected cathodes of the diodes 13 and 15. The cathode of this thyristor 2S is connected - 20 to the anode of a diode 27 whose cathode is connected to the negative conductor.19. A control electrode of the thyristor 25 is also connected to the conductor 19.
The emitter of a ~-transistor 28 is connected to the conductor 20 and the emitter of an npn-transistor 29 2S is connected to the conductor 19. The base of the tran-sistor 2.8 is connected to the collector of the transistor 299 and the base of the transistor 29 is connected to the PHF.77-505 20.1Z.77 collector of the transistor 28. Furthermore, the base of the transistor 28 is connected via a resistor 30 to the conductor 20. In addition~ the base of the transistor 29 is connected via a resistor 31, which has a negative temperature coefficient, to the conductor 19. The resistor 31 is thermally coupled to the inductance 26.
The cathode of a zener diode 32 is connected to the conductor 20, and the anode of this diode 32 is connected to the base of the transistor 29. A resistor 33 is connected between the oonduc-tors 20 and 19. The conductor 20 is connected via a capacitor 34 to the cathode of the thyristor 25 Fig. 2 shows an electric circuit of a second electronic starter 120, whose input terminals 10 and 11 .15 are connected to electrodes 1 and 2.of a lamp 3 in a similar manner to that shown in Fig. 1. The components in Fig. 2 which are the same as in Fig 1 have been given the same reference numerals. However, the temperature-sensitive resistor 31 of Fig. 1 i5 replaced by a fixed resistor 310, whereas resistor 30 is replaced by a resistor 300 having a positive temperature coefficient.
In addition, that resistor 300 is thermally coupled to the :inductance 26.
The igniting pulses which are supplied by means of the starters 12 and 120 of Figs. 1 and 2 resemble the igniting pulses which can be obtained with a starter according to the previously mentioned French Patent Application No.2,279,302.
_g_ P~IF.77-505 20,12.77 .
The intensity of the hold current ~IH) of ~he thyristor 25 is increased by the provision of diode 27.
Via its cathode this thyristor 25 is made conductive by negative pulses which are supplied by discharges of the capacitor 3LI~ which capacitor is charged via the input terminals 10 and 11.
The use of thyristor 25, having an (apparently) large hold current, in series with inductance 26 causes the ballast circuit to be alternately conducting and interrupted at a very high frequency and hence promotes ignition of the lamp. The electric asymmetry of the described starter furthermore results in a direct current compo~ent in the current through the stabilisation ballast, which lS advantageous because this increases - 15 the pre-heating current of the lamp electrodes 1 and 2, -owing to magnetic saturatlon of the inductance of the ballast. This is of course only the case during the starting procedure; not during the operating condition of the lamp.
The starters 12 and 1209 of the Figs. 1 and 2, operate as follows:
Initially the voltage between the conductors 19 and 20 is equal to zero, capacitor 34 is uncharged, and the transistors 28 and 29 are cut off. If the voltage between -the terminals 10 and 11 is increased, the capacitor 34 is charged until the voltage between the conductors 19 and 20 attains the threshold voltage PHF.77-505 ~4~ 20.12.77 of the zener diode 32. This diode 32 then becomes conductive and this results in a current through the t base of the transistor Z9, which becomes conductive as a result thereof. In its turn this renders the trans~tor 28 conductive.
As this process is comulative, the two transistors are brought in a very short period of time into the saturation state, which results in a rapid partial disc~harge of the capacitor 34~ so that indirectly a control pulse is supplied to the control ` electrode of the thyristor 25.
The above procedure repeats itself very frequently during a fraction of a half cycle of the mains voltage supply, to render the thyristor conductive.
The same occurs thereafter in the next half cycle but in a somewhat asymmetrical manner.
The starters 12 and 120 shown in Figs. 1 and 2 respectively are electrically arranged so that an interruption or accidental short-circuiting of the temperature-sensitive resistor 31 or 300 of these starters does not result in an excessive current through the stabilisation ballast (6 or 7).
; In the case of a normally-igniting lamp, the operation of the starter is immediately blocked after ignition of the lamp 3. This is caused by the fact that the voltage between the input terminals lO and 11 decreases to the ope~ating voltage of the lamp.
... . . :
P~IF.~7-50 20.12.77 Consequently the threshold voltage of the ~ener diode 32 is not attained. Furthermore this results in the fact t that the temperature-sensitive resistor 31 - in the operating condition of the lamp 3 - receives no f`urther current. Therefore that temperature-sensitive resistor assumes a temperature which is substantially the same as the ambient temperature. After a very brief interruption of the mains voltage the resistor 31, which is then cold, does not inhibit - after extinction - the re-ignition of the lamp 3. The same applies in a corresponding manner to the further embodiments of electronic starters des-cribed hereinafter.
If the lamp 3 fails to ignite, the conducting state of the thyristor 25 results in that the ballast current then comprises a direct current component which gives a reduction of the e~ective impedance o* the inductance of the ballast. The temperature of -the ballast might then become higher than the temperature prescribed for sa~ety reasons. However, the starters 12 and 120 are arranged so that they limit heating of the ballast to a temperature which is perfectly safe.
As regards the starter 12 of Fig. 1, reducing the value of the negative temperature coef~icient (NTC) resistor 31 a~ter heating thereof results in that the transistor 29 approaches its non-conductive s*ate, which ~esults in a delay in the discharge of the capacitor 34 at the beginning o~ each half cycle.
.
.
PflF.77.505 2Q 12 r~7 As regards the starter 120 of Fig.2, the increasing value of the positive tenlperature coefficient (PTC) 300 results in that the collector current o~ the transistor 29, and consequently also the base curreht of the transistor 28, then decreases, which also results in a delay in generating a control pulse by means of the capacitor 34.
Fig. 3 which, in~er alia7 shows the variation of the voltage between the electrodes of the lamp 3 in the case of an inductive ballast 6, shows the shift in the ignition instant in the positive half cycles during heating of the NTC resistor 31 or of the PTC resistor 300.
Consequently Figure 3 shows that the duration of the time interval (t1-t2, t2-t4 and t5-t6) during which the thyristor 25 conducts, has considerably decreased.
This redults in a reductinn of the effective ballast current, the intensity of which stabilizes at a value which is without any risk for that ballast.
For the starters 12 and 120 of Figs 1 and 2, such safety is ensured and this applies even if the temperature-sensitive resistors 31~ 300 are short-circuited or are open-circuited due to a fault in either of the~.
In the case where resistor 31 or 300 is s;hort-circuited, the transistors 28 and 29 cannot become conducti~e so that the thyristor 25 cannot become oonductive.
So substantially no current flows through the ballast then.
, PHF.77-505 20.12 77 In the case where the ~TC resi.stor 31 is open circuit, the intensity of thc current received via the zener diode 32 is sufficient to keep the transistor 29 conductive, whereas in the case where the PTC resistor 300 is open the transistor 28 is aiso rendered conductive.
. In these fault conditions a single pulse of a weak amplitude (Fig.L~) is observe~ during each positive half` cycle. That pulse is due. to a.si.ngle discharge of the capacitor 2l~ via the conducting transistors 28 and 29 Consequently the high frequency oscillation process does not continue.. Also ln this case -there is substanti-. ally no current flow through the stabilisation ballast of the lamp; i.e. a safe condition is established.
. In certain circumstances it may be advantageous to reduce the intensity of the ballast current - in the -; case of a failing lamp, for example, to a negligibly low - value, particularly, in the case where all the lamps of a large lighting installation are replaced at substantially the same time and hence tend to fail at ZO the same time. Otherwise the totai intensity of the - ~ ballast currents of the simultaneously failing.lamps would result in a considerable waste of` energy.
; The starter 121 shown in Fig. 5, which also enabIes a reduction in the ballast current,`
comprises a series arrangement of a.resistor 35 and a negati~e temperature coefficient (~TC) resistor 36 .. . . . .
between the interconnected cathodes of the diodes 13, 15 and the conductor 19.
~L$~ PHF; r~7 505 If the lamp does not ignite, the voltage across the series arrangement 35, 36 remains high.
This results in an increase in temperature of these two resistors. Owing to the thermal coupling to the negative - temperature coe~ficient resistor 31 the ohmic value of the latter decreases considerably, so that the transistor 29 as well as the thyristor 25 become non-conducting.
The strength of the current, which then flows between the terminals 10 and 11 of the starter is substantially reduced to the sum of the current through the zener diode 32 and the current through the resistors 35 and 36, that is to say, as a rule, to a few milliamp~res.
It would also be possible to-obtain the same final result, i.e. reducing the ballast current substantially to zero, by providing thermal coupling of` the temperature-sensitive resistors 31 and 36 only.
~owever, it is often desired also to maintain the thermal coupling to the inductance 26. This results in that the reduction of the current is accelerated by a pronourlced increase in the temperature of the NTC resistor 31.
The sta~ter 122 of Fig. 6, in which the sa~e ref`erence numerals are used as in Figs. 1p 2 and 5, comprises, by way of switching arrangement, a tetrods thyristor 37, a control electrode of which is connected to the conductor 20 via a resistor 30. A further control electrode of` 37 is connected to a junction between the anode of the zener diode 32 and the resistor 31.
PJI~.77~505 ~ 20.12.77 The thyristor 37 of Fig. 6 switches in a similar manner to the combination formed by the transistors 28 and 29 of Figs. 1, 2 and 5.
In Fig. 7 a unijunction transistor 38 is used as the auxiliary switch of the starter 123. In the circuit of Fig. 8 a thyristor 39 is used, for the sams purposs, for the starter 124.
Contrary to the starters described above, the starters 123 and 124 are not suitable for the embodiment in which a resistor having a positive tem-perature coefficient is used, owing to the fact tha-t the auxiliary switch comprises one control electrode only.
But for this restriction the starters 123 and 124 of Fig. 7 and Fig. 8 respectively are ~ully comparable to the starters 12, 120, 121 and 122.
Figs. 9 and 10 show two embodiments for effecting the thermal coupling of the various components of the starter 121 of Fig. 5.
, Ths inductance 26 of Fig. 9 and Fig. 10 consists of a double cylindrical ferrite core wound with wire. An electrically insula*ing film 40 is present between the inductance 26 and the resistors 31, 35 and 36.
The assembly thus formed is clamped together by means of an envelope 41 of a resilient synthetic resin material.
Ths diameter of the electric wire of the inductance 26 is sufficiently small to ensure rapid heating of the inductance if the lamp fails to ignite.
:
` -~ PHFj77-505 The NTC resistor 23 (see Fig. 1, 2y 5, 6, 7, and 8) serves inter alia to prevent the thyristor 25 -from becoming conductive after the ignition of the lamp 3 over the ent:ire range of ambient temperatures in which the starter should function.
~17-!
: ~ .............. . : .
.
~MF.77-505 20.12.77 of the type mentioned in the preamble, wherein the above-mentioned protection is obtained by m~ans of a resistor having a negative tempera-ture coefficient (NTC).
In an embodiment of that; ~rench Patent Application this resistor is arranged in parallel with a capaci-tor which is part of the control aircuit of the semiconductor switch of the starter.
A drawbac~ of that prior art electronic starter is that, in the operating condition of the lamp, an electric current flows continuously through the NTC resistor~ so that it is difficult, and sometimes even impossible, - after a brief interruption of the power supply malns, - to ignite the lamp again after it has extinguished.
A second drawback of the above-mentioned prior art electronic starter is that an accidental interruption of the NTC resistors puts the pro-tection of the ballast out of operation in the case of a lamp which fails to ignite.
It is an object of the invention to provide :^ an electronic starter of the type mentioned in the preamble by means of which the discharge lamp to be ignited by it can rapidly re-ignite even after a short ` interruption of the mains voltage.
In addition it is an object of the invention to provide certain classes of electronic starters of the _3_ ,-:
PHF.77-505 20.12.77 type mentioned in the preamble, which do not only obviate the ~irst-mentioned drawback but also the second drawback. That is to say that in that case certain defects in the temperature-sensitiVé circuit c~mponent do not result :in damage to the lighting device to which said starter is connected. This means here that an interruption in the temperature-sensitive circuit component or an accidental short-circuit o~
that temperature-sensitive circuit component of the starter may not rasult in an excessive electric current through the stabilisation ballast of the lamp.
An electronic starter according to the invention for igniting a discharge lamp, this starter having two input terminals which are interconnected by an electric circuit comprising at least a controlled semiconductor switch, the starter furthermore comprising a control circuit controlling said semiconductor switch, this control circuit comprising a temperature-sensitive circuit element which inhibits the igniting function of the starter at an elevated temperature, is characterized is that the control circuit of the controlled semi-conductor switch comprisies an auxiliary switch which is connected to the temperature-sensitive circult element, the auxiliary switch being controlled by a threshold voltage element, and the auxiliary switch being open if the voltage across the threshold voltage element is lower than its threshold voltage.
. -4-PHF.77 50 20.12.77 An advantage of this electronic starter is that, after a very brief interruption in the mains voltage, the Eelevant discharge-lamp after extinguishing -can again ignite reliably. This is the result of the ~act that the temperatu:re-sensitive circuit element carries no current in the opera-ting condition of the lamp.
The temperature of that temperature-sensitive circuit element can consequently be sufficiently low - after a very brief interrupt:ion in the mains voltage has ended to enable re-ignition of the lamp.
The threshold voltage component is preferably R zener diode. In addition, it is advantageous if the temperature-sensitive circuit element is thermally coupled to one of the starter components in which the - 15 current flows which passes through the stabilisation ballast. As a result thereof, that ballast current can be kept low in the case of a failing lamp.
With a further preferred embodiment of an electronic starter according to the invention a further resistor is present in parallel with the circuit which includes the semiconductor switch, and the temperature-sensitive circuit elemen-t is thermally coupled to that additional resistor. ~n advantage thereof is that the ballast current - in the case of a failing lamp - can also ~e kept low.
In the two last-mentioned embodiments the temperature-sensitive circuit element is not only _5_ ' P~IF.77-505 20.12.77 heated by the electric current ~lowing through the temperature-sensitive circuit element itself.
Electronie starters according to the present inventinn may reduce - in the case of a failing lamp -the ballast current to a harmlessly low value. This value need not be equal to zero. Owing to a suitable témperature increase of the temperature-sensitive circuit element whieh is present in the control circuit of the controlled semiconductor switch, it can be ensured that that con-trolled semiconductor switeh - which then carries the ballast current - is only occasionally condueting.
Then the ballast current assumes, after an ~nitial high value, a low final value.
Some embodiments of electronie starters aecording to the invention will now be deseribed with reference to the aecompanying drawings, in which:
Fig. 1 shows a first electric circuit comprising a diseharge lamp and an eleetronic starter according to the invention;
Fig. 2 shows an electric eircuit of a seeond eleetronie starter according to the invention;
Fig. 3 shows schematica~y the waveform of the electric voltage between the input terminals of the starter, plotted against time, in the circuits of Fig.1 and Fig. 2, if the discharge lamp does ~t immediately ignite, Fig. 4 shows schematically the waveform of the electric voltage between the input terminals of the ~6_ PHF.77-505 20.12.77 starter, plotted against time, in the circuits of Fig.1 and Fig.2, if a temperature-sensitive circuit element in that starter is defective;
Fig. 5 shows an electric circuit of a third electronic starter according to the invention;
Fig. 6 shows an electric circuit of a fourth electronic starter according to the invention;
Fig. 7 shows an electric circuit o~ a fifth electronic starter according to the invention;
.10 Fig. 8 shows an electric circuit of a sixth èlectronic starter according to the invention;
Fig. 9 shows a cross-section through a portion of the electronic starter of Fig. 5; and Fig. 10 shows a variant of the cross-section of Fig. ~ of an electronic starter.
In Fig. 1 references 1 and 2 denote preheatable electrodes of a low-pressure mercury vapour discharge lamp 3. The electrode 1 is connected to a terminal 4.
The electrode 2 is connected to a terminal 5 of an a.c~ voltage mains supply of, for example, 220 volts, 50 Hz.
Connected to the terminal 4 there is a stabi-lisation ballast which is either inductive (ballast 6) or consists of a series arrangement of an electric coil and a capacitor, which series arrangement (ballast 7) is capacitive at the above-mentioned mains frequency.
The other end o~ the relevant ballast is connacted to a terminal 8 ~hich is connected to a second terminal 9 of the a.o. voltage mains.
i -7 .
PHF~77~5o5 20.12.77 The two ends of the electrodes 1 and 2 of the lamp 3 remote from the supply mains are connected to input terminals IO and 11 respectively of an electronic starter 12. The starter 12 serves for igrliting the lamp 3.
A diode bridge .13 to 16 inclusive is connected to -the terminals 10 and 11. In addition, the terminals 10 and 11 are interconnected via a capacitor 17 and a teMperature~
. sensitive auxiliary resistor 18.
. The interconnected anodes of the diodes 11~
10- and 16 are connected to a common conductor 19 (negative conductor).
A conductor 20 (positive conductor) is connected via a series arrangement of two resistors 22 and 21 to the terminal 10. The resistor 21 is shunted by a resistor 23 having a negative temperature coefficient. The conductor 20 is connected to the terminal 11 via a resistor 24.
Via an inductance 26 the anode of a thyristor 25 is.connected to the interconnected cathodes of the diodes 13 and 15. The cathode of this thyristor 2S is connected - 20 to the anode of a diode 27 whose cathode is connected to the negative conductor.19. A control electrode of the thyristor 25 is also connected to the conductor 19.
The emitter of a ~-transistor 28 is connected to the conductor 20 and the emitter of an npn-transistor 29 2S is connected to the conductor 19. The base of the tran-sistor 2.8 is connected to the collector of the transistor 299 and the base of the transistor 29 is connected to the PHF.77-505 20.1Z.77 collector of the transistor 28. Furthermore, the base of the transistor 28 is connected via a resistor 30 to the conductor 20. In addition~ the base of the transistor 29 is connected via a resistor 31, which has a negative temperature coefficient, to the conductor 19. The resistor 31 is thermally coupled to the inductance 26.
The cathode of a zener diode 32 is connected to the conductor 20, and the anode of this diode 32 is connected to the base of the transistor 29. A resistor 33 is connected between the oonduc-tors 20 and 19. The conductor 20 is connected via a capacitor 34 to the cathode of the thyristor 25 Fig. 2 shows an electric circuit of a second electronic starter 120, whose input terminals 10 and 11 .15 are connected to electrodes 1 and 2.of a lamp 3 in a similar manner to that shown in Fig. 1. The components in Fig. 2 which are the same as in Fig 1 have been given the same reference numerals. However, the temperature-sensitive resistor 31 of Fig. 1 i5 replaced by a fixed resistor 310, whereas resistor 30 is replaced by a resistor 300 having a positive temperature coefficient.
In addition, that resistor 300 is thermally coupled to the :inductance 26.
The igniting pulses which are supplied by means of the starters 12 and 120 of Figs. 1 and 2 resemble the igniting pulses which can be obtained with a starter according to the previously mentioned French Patent Application No.2,279,302.
_g_ P~IF.77-505 20,12.77 .
The intensity of the hold current ~IH) of ~he thyristor 25 is increased by the provision of diode 27.
Via its cathode this thyristor 25 is made conductive by negative pulses which are supplied by discharges of the capacitor 3LI~ which capacitor is charged via the input terminals 10 and 11.
The use of thyristor 25, having an (apparently) large hold current, in series with inductance 26 causes the ballast circuit to be alternately conducting and interrupted at a very high frequency and hence promotes ignition of the lamp. The electric asymmetry of the described starter furthermore results in a direct current compo~ent in the current through the stabilisation ballast, which lS advantageous because this increases - 15 the pre-heating current of the lamp electrodes 1 and 2, -owing to magnetic saturatlon of the inductance of the ballast. This is of course only the case during the starting procedure; not during the operating condition of the lamp.
The starters 12 and 1209 of the Figs. 1 and 2, operate as follows:
Initially the voltage between the conductors 19 and 20 is equal to zero, capacitor 34 is uncharged, and the transistors 28 and 29 are cut off. If the voltage between -the terminals 10 and 11 is increased, the capacitor 34 is charged until the voltage between the conductors 19 and 20 attains the threshold voltage PHF.77-505 ~4~ 20.12.77 of the zener diode 32. This diode 32 then becomes conductive and this results in a current through the t base of the transistor Z9, which becomes conductive as a result thereof. In its turn this renders the trans~tor 28 conductive.
As this process is comulative, the two transistors are brought in a very short period of time into the saturation state, which results in a rapid partial disc~harge of the capacitor 34~ so that indirectly a control pulse is supplied to the control ` electrode of the thyristor 25.
The above procedure repeats itself very frequently during a fraction of a half cycle of the mains voltage supply, to render the thyristor conductive.
The same occurs thereafter in the next half cycle but in a somewhat asymmetrical manner.
The starters 12 and 120 shown in Figs. 1 and 2 respectively are electrically arranged so that an interruption or accidental short-circuiting of the temperature-sensitive resistor 31 or 300 of these starters does not result in an excessive current through the stabilisation ballast (6 or 7).
; In the case of a normally-igniting lamp, the operation of the starter is immediately blocked after ignition of the lamp 3. This is caused by the fact that the voltage between the input terminals lO and 11 decreases to the ope~ating voltage of the lamp.
... . . :
P~IF.~7-50 20.12.77 Consequently the threshold voltage of the ~ener diode 32 is not attained. Furthermore this results in the fact t that the temperature-sensitive resistor 31 - in the operating condition of the lamp 3 - receives no f`urther current. Therefore that temperature-sensitive resistor assumes a temperature which is substantially the same as the ambient temperature. After a very brief interruption of the mains voltage the resistor 31, which is then cold, does not inhibit - after extinction - the re-ignition of the lamp 3. The same applies in a corresponding manner to the further embodiments of electronic starters des-cribed hereinafter.
If the lamp 3 fails to ignite, the conducting state of the thyristor 25 results in that the ballast current then comprises a direct current component which gives a reduction of the e~ective impedance o* the inductance of the ballast. The temperature of -the ballast might then become higher than the temperature prescribed for sa~ety reasons. However, the starters 12 and 120 are arranged so that they limit heating of the ballast to a temperature which is perfectly safe.
As regards the starter 12 of Fig. 1, reducing the value of the negative temperature coef~icient (NTC) resistor 31 a~ter heating thereof results in that the transistor 29 approaches its non-conductive s*ate, which ~esults in a delay in the discharge of the capacitor 34 at the beginning o~ each half cycle.
.
.
PflF.77.505 2Q 12 r~7 As regards the starter 120 of Fig.2, the increasing value of the positive tenlperature coefficient (PTC) 300 results in that the collector current o~ the transistor 29, and consequently also the base curreht of the transistor 28, then decreases, which also results in a delay in generating a control pulse by means of the capacitor 34.
Fig. 3 which, in~er alia7 shows the variation of the voltage between the electrodes of the lamp 3 in the case of an inductive ballast 6, shows the shift in the ignition instant in the positive half cycles during heating of the NTC resistor 31 or of the PTC resistor 300.
Consequently Figure 3 shows that the duration of the time interval (t1-t2, t2-t4 and t5-t6) during which the thyristor 25 conducts, has considerably decreased.
This redults in a reductinn of the effective ballast current, the intensity of which stabilizes at a value which is without any risk for that ballast.
For the starters 12 and 120 of Figs 1 and 2, such safety is ensured and this applies even if the temperature-sensitive resistors 31~ 300 are short-circuited or are open-circuited due to a fault in either of the~.
In the case where resistor 31 or 300 is s;hort-circuited, the transistors 28 and 29 cannot become conducti~e so that the thyristor 25 cannot become oonductive.
So substantially no current flows through the ballast then.
, PHF.77-505 20.12 77 In the case where the ~TC resi.stor 31 is open circuit, the intensity of thc current received via the zener diode 32 is sufficient to keep the transistor 29 conductive, whereas in the case where the PTC resistor 300 is open the transistor 28 is aiso rendered conductive.
. In these fault conditions a single pulse of a weak amplitude (Fig.L~) is observe~ during each positive half` cycle. That pulse is due. to a.si.ngle discharge of the capacitor 2l~ via the conducting transistors 28 and 29 Consequently the high frequency oscillation process does not continue.. Also ln this case -there is substanti-. ally no current flow through the stabilisation ballast of the lamp; i.e. a safe condition is established.
. In certain circumstances it may be advantageous to reduce the intensity of the ballast current - in the -; case of a failing lamp, for example, to a negligibly low - value, particularly, in the case where all the lamps of a large lighting installation are replaced at substantially the same time and hence tend to fail at ZO the same time. Otherwise the totai intensity of the - ~ ballast currents of the simultaneously failing.lamps would result in a considerable waste of` energy.
; The starter 121 shown in Fig. 5, which also enabIes a reduction in the ballast current,`
comprises a series arrangement of a.resistor 35 and a negati~e temperature coefficient (~TC) resistor 36 .. . . . .
between the interconnected cathodes of the diodes 13, 15 and the conductor 19.
~L$~ PHF; r~7 505 If the lamp does not ignite, the voltage across the series arrangement 35, 36 remains high.
This results in an increase in temperature of these two resistors. Owing to the thermal coupling to the negative - temperature coe~ficient resistor 31 the ohmic value of the latter decreases considerably, so that the transistor 29 as well as the thyristor 25 become non-conducting.
The strength of the current, which then flows between the terminals 10 and 11 of the starter is substantially reduced to the sum of the current through the zener diode 32 and the current through the resistors 35 and 36, that is to say, as a rule, to a few milliamp~res.
It would also be possible to-obtain the same final result, i.e. reducing the ballast current substantially to zero, by providing thermal coupling of` the temperature-sensitive resistors 31 and 36 only.
~owever, it is often desired also to maintain the thermal coupling to the inductance 26. This results in that the reduction of the current is accelerated by a pronourlced increase in the temperature of the NTC resistor 31.
The sta~ter 122 of Fig. 6, in which the sa~e ref`erence numerals are used as in Figs. 1p 2 and 5, comprises, by way of switching arrangement, a tetrods thyristor 37, a control electrode of which is connected to the conductor 20 via a resistor 30. A further control electrode of` 37 is connected to a junction between the anode of the zener diode 32 and the resistor 31.
PJI~.77~505 ~ 20.12.77 The thyristor 37 of Fig. 6 switches in a similar manner to the combination formed by the transistors 28 and 29 of Figs. 1, 2 and 5.
In Fig. 7 a unijunction transistor 38 is used as the auxiliary switch of the starter 123. In the circuit of Fig. 8 a thyristor 39 is used, for the sams purposs, for the starter 124.
Contrary to the starters described above, the starters 123 and 124 are not suitable for the embodiment in which a resistor having a positive tem-perature coefficient is used, owing to the fact tha-t the auxiliary switch comprises one control electrode only.
But for this restriction the starters 123 and 124 of Fig. 7 and Fig. 8 respectively are ~ully comparable to the starters 12, 120, 121 and 122.
Figs. 9 and 10 show two embodiments for effecting the thermal coupling of the various components of the starter 121 of Fig. 5.
, Ths inductance 26 of Fig. 9 and Fig. 10 consists of a double cylindrical ferrite core wound with wire. An electrically insula*ing film 40 is present between the inductance 26 and the resistors 31, 35 and 36.
The assembly thus formed is clamped together by means of an envelope 41 of a resilient synthetic resin material.
Ths diameter of the electric wire of the inductance 26 is sufficiently small to ensure rapid heating of the inductance if the lamp fails to ignite.
:
` -~ PHFj77-505 The NTC resistor 23 (see Fig. 1, 2y 5, 6, 7, and 8) serves inter alia to prevent the thyristor 25 -from becoming conductive after the ignition of the lamp 3 over the ent:ire range of ambient temperatures in which the starter should function.
~17-!
: ~ .............. . : .
.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS
1. An electronic starter for igniting a discharge lamp, the starter having two input terminals inter-connected by an electric circuit comprising at least a controlled semiconductor switch, the starter further-more comprising a control circuit for controlling said semi-conductor switch, this control circuit comprising a temperature-sensitive circuit element which inhibits at an elevated temperature the igniting function of the starter, characterized in that the control circuit of the controlled semiconductor switch comprises an auxiliary switch connected to the temperature-sensitive circuit element, the auxiliary switch being controlled by a threshold voltage element, and the auxiliary switch being open if the voltage across the threshold voltage element is lower than its threshold voltage.
2. An electronic starter as claimed in Claim 1, characterized in that the auxiliary switch consists of a semiconductor device.
3. An electronic starter as claimed in Claim 2, characterized in that the temperature-sensitive circuit element is a resistor having a negative temperature coefficient (NTC), a first terminal of that NTC resistor is connected to a first electrode of the semiconductor device and the other terminal of the NTC resistor is connected to a second electrode of the semiconductor device, and in that this semiconductor device is non-conducting when the difference in potential between said electrodes is zero.
PHN.77-505 20.12.77
PHN.77-505 20.12.77
4. An electronic starter as claimed in Claim 2, characterized in that the temperature-sensitive circuit element is a resistor having a positive temperature coefficient (PTC), a first end of the PTC resistor is connected to a first electrode of the semiconductor device, and the other end of the PTC resistor is connected to a second electrode of the semiconductor device, and that this semiconductor device is conductive if the difference in potential between said electrodes is zero.
5. An electronic starter as claimed in Claim 1, characterized in that the threshold voltage element is a zener diode.
6. An electronic starter as claimed in Claim 3, characterized in that the semiconductor device consists of a combination of an npn-transistor and a pnp-transistor wherein the base electrode of each of these transistors is connected to the collector electrode of the other transistor, and the NTC resistor interconnects the base and the emitter of the npn-transistor.
7. An electronic starter as claimed in Claim 4, characterized in that the semiconductor device consists of a combination of an npn-transistor and a pnp-transistor, the base electrode of each of the transistors being connected to the collector electrode of the other transistor, and in that the PTC resistor interconnects the base and the emitter of the pnp-transistor.
8. An electronic starter as claimed in Claim 2, characterized in that the semiconductor device is a thyristor.
9. An electronic starter as claimed in Claim 1, characterized in that the temperature sensitive circuit element is thermally coupled to an inductance which is arranged in series with the controlled semiconductor switch.
10. An electronic starter as claimed in Claim 1, characterized in that a further resistor is present in parallel with the circuit comprising the semiconductor switch, and that the temperature-sensitive circuit ele-ment is thermally coupled to that additional resistor.
11. An electric circuit comprising a gas and/or vapour discharge lamp, provided with at least two elec-trodes, and an electronic starter as claimed in Claim 1, one input terminal of the starter being connected to one electrode of the lamp and the other input terminal of the starter being connected to the other electrode of the lamp.
12. An electric circuit as claimed in Claim 11, characterized in that the lamp comprises preheatable electrodes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7702585 | 1977-01-31 | ||
| FR7702585A FR2379226A1 (en) | 1977-01-31 | 1977-01-31 | ELECTRONIC STARTER FOR PRIMING A DISCHARGE TUBE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1114889A true CA1114889A (en) | 1981-12-22 |
Family
ID=9186072
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA295,704A Expired CA1114889A (en) | 1977-01-31 | 1978-01-26 | Electronic starter for igniting a discharge lamp |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US4177403A (en) |
| JP (1) | JPS5394465A (en) |
| BE (1) | BE863467A (en) |
| CA (1) | CA1114889A (en) |
| CH (1) | CH625379A5 (en) |
| DE (1) | DE2802218A1 (en) |
| ES (1) | ES466449A1 (en) |
| FR (1) | FR2379226A1 (en) |
| GB (1) | GB1569045A (en) |
| IT (1) | IT1091999B (en) |
| NL (1) | NL7800988A (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4378514A (en) * | 1980-10-27 | 1983-03-29 | General Electric Company | Starting and operating circuit for gaseous discharge lamps |
| JPS5774996A (en) * | 1980-10-29 | 1982-05-11 | Tokyo Shibaura Electric Co | Device for firing discharge lamp |
| NL8103507A (en) * | 1981-07-24 | 1983-02-16 | Philips Nv | ELECTRICAL DEVICE FOR IGNITION AND POWERING A LOW PRESSURE DISCHARGE LAMP. |
| US4437042A (en) | 1981-12-10 | 1984-03-13 | General Electric Company | Starting and operating circuit for gaseous discharge lamps |
| JPH07105272B2 (en) * | 1983-10-19 | 1995-11-13 | 日立照明株式会社 | Separately excited inverter type discharge lamp lighting device |
| DE3417794A1 (en) * | 1984-05-14 | 1985-11-14 | Philips Patentverwaltung Gmbh, 2000 Hamburg | CIRCUIT ARRANGEMENT FOR CONTROLLING THE BURN VOLTAGE OF HIGH PRESSURE GAS DISCHARGE LAMPS |
| GB2194400B (en) * | 1986-08-04 | 1991-04-17 | Transtar Ltd | Starter and discharge lamp including it |
| US4777410A (en) * | 1987-06-22 | 1988-10-11 | Innovative Controls, Inc. | Ballast striker circuit |
| BE1007611A3 (en) * | 1993-10-11 | 1995-08-22 | Philips Electronics Nv | Shifting. |
| US5583395A (en) * | 1994-10-11 | 1996-12-10 | Lu; Chao-Cheng | Fluorescent device having a fluorescent starter which precisely controls heating time and absolute synchronism of fire point |
| US5606224A (en) * | 1995-11-22 | 1997-02-25 | Osram Sylvania Inc. | Protection circuit for fluorescent lamps operating at failure mode |
| IL116250A0 (en) * | 1995-12-04 | 1996-03-31 | Vainer Shimon | Improved starting device for fluorescent lamps |
| US5777439A (en) * | 1996-03-07 | 1998-07-07 | Osram Sylvania Inc. | Detection and protection circuit for fluorescent lamps operating at failure mode |
| DE19613077C2 (en) * | 1996-04-02 | 1999-10-14 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Circuit arrangement for operating electric lamps, especially free-swinging half-bridge converters |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1026817A (en) * | 1972-05-09 | 1978-02-21 | Michel Remery | Electrical circuit for igniting and supplying a discharge lamp |
| US3978368A (en) * | 1973-02-21 | 1976-08-31 | Hitachi, Ltd. | Discharge lamp control circuit |
| FR2255777A1 (en) * | 1973-12-21 | 1975-07-18 | Radiotechnique Compelec | Firing system for discharge tubes - has common point of RC network connected to preheated electrode by resistor |
| JPS50102184A (en) * | 1974-01-21 | 1975-08-13 | ||
| FR2279302A1 (en) * | 1974-07-16 | 1976-02-13 | Radiotechnique Compelec | Starting circuit for discharge tube - has thyristor and inductor in series to maintain voltage peaks constant |
| FR2285780A1 (en) * | 1974-09-18 | 1976-04-16 | Radiotechnique Compelec | DEVICE INTENDED TO PRIME A DISCHARGE TUBE |
-
1977
- 1977-01-31 FR FR7702585A patent/FR2379226A1/en active Granted
-
1978
- 1978-01-16 US US05/870,026 patent/US4177403A/en not_active Expired - Lifetime
- 1978-01-19 DE DE19782802218 patent/DE2802218A1/en not_active Withdrawn
- 1978-01-26 CA CA295,704A patent/CA1114889A/en not_active Expired
- 1978-01-27 GB GB3371/78A patent/GB1569045A/en not_active Expired
- 1978-01-27 NL NL7800988A patent/NL7800988A/en not_active Application Discontinuation
- 1978-01-27 IT IT19731/78A patent/IT1091999B/en active
- 1978-01-28 ES ES466449A patent/ES466449A1/en not_active Expired
- 1978-01-28 JP JP786378A patent/JPS5394465A/en active Pending
- 1978-01-30 BE BE184752A patent/BE863467A/en not_active IP Right Cessation
- 1978-01-30 CH CH100378A patent/CH625379A5/de not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| FR2379226A1 (en) | 1978-08-25 |
| IT1091999B (en) | 1985-07-06 |
| ES466449A1 (en) | 1978-10-16 |
| DE2802218A1 (en) | 1978-08-03 |
| CH625379A5 (en) | 1981-09-15 |
| US4177403A (en) | 1979-12-04 |
| JPS5394465A (en) | 1978-08-18 |
| NL7800988A (en) | 1978-08-02 |
| BE863467A (en) | 1978-07-31 |
| GB1569045A (en) | 1980-06-11 |
| IT7819731A0 (en) | 1978-01-27 |
| FR2379226B1 (en) | 1980-11-21 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |