CA2051447A1

CA2051447A1 - Fluorescent lamp

Info

Publication number: CA2051447A1
Application number: CA002051447A
Authority: CA
Inventors: Werner Reinig
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-04-04
Filing date: 1990-04-03
Publication date: 1990-10-05
Also published as: DE59001722D1; AU5413790A; WO1990012417A1; DE9007438U1; EP0466749B1; DE8904130U1; EP0466749A1

Abstract

Abstract of the Disclosure A fluorescent lamp, particularly a mercury discharge lamp, with a discharge tube, which is transparent to light and with which an ohmic heating wire is in thermalcontact with a heat-sensitive filament, for example of glass, wire or some otherstrand, which extends along the discharge tube and is surrounded preferably spirally by the heating wire as the inner guide core for this wire.

Description

o 205~447 ;

F-4 168(FJ) FLUORE~SCENT LAMP

The invention relates to a fluorescent lamp, particularly a mercu~y vapor discharge lamp, with a discharge tube, which is transparent to light and preferably of glass, S with which the ohmic heating wire is in thermal contact.

As is wcll known, fluorescent lamps usually consis~ of an extended discharge tube of glass, into the ends of which hot electrodes are fused. As a rule, the tube is evacuated and filled with krypton, argon and mercury. Known fluorescent lamps are generally operated by mains voltage. For this purpose, a choke coil and a starter are rcquircd to fire the gas discharge. However, ~he choke and the starter lead to additional consumption of energy or to a decrease in the efficiency, as well ~:i as to an inductivc or wattless current load on the alternating-current mains supply.
In addition, furthcr compcnsation and radio noise suppression mcasures arc re-quircd.

- 15 ~dmittedly, fluorcsccnt lamps with an attached powcr supply, which rectifies the altcrnating currcnt from thc mains suppl~ for dircct current operation, arc known.
Hswevcr, thc direct curren,t must be modulated to a high frequcncy and/or chopped, in order to prcvent polarizaflon at the ends of the hot electrodcs of thc dischargc tube; otherwise, the mercury present in ~he dischargc tube would be depositcd atonc end of ~he dischargc tube, which would then bccome useless within a few hours.

The problem, on whicll the invention is based, follows from this, the prohlem bein~
to avoid the disadvantages mentioned above and to provide a fluorescent lamp, which uses current sparingly and, at the same time, is reliable in itS operation, and to do so with only little additional circuit complcxity, it being possible, in particular, to use conventional, commercial, standard fluorescent tubes. To solve this problem, it is proposed, pursuant to the invention, for a fluorescent lamp with the character-istics initially named, that a heat-insensitive filament, ~or example of glass, wire or some other strand, be provided, which extends along the discharge tube and is surrounded, preferably spirally by the heating wire as the inner guide core for the latter.

When operated pursuant to the invention, the discharge tube is in constant, thermal contact with a heatcr, which is structurally intcgrated in the fluorescent lamp and with which the opcrating tempcrature for the dischargc gas in the tube can bc optimized. Mercury, as dischargc gas, for example, can bc heated in ~his manncr to a tcmperaturc, at which it is constan~ly in thc vapor or gaseous statc, its boiling point being excecdcd. Thercforc, due to the hca~ing, it is dispcrsed over thc whole of thc discharge tube and is not dcposited at one end of the hot electrodes of the discharge tube, although thc hot clectrodes are subjectcd to a direct currcnt opera-tion and the discharge tube thcrefore is polarized. A furthcr advantage, which is achievcd with the invention, cgnsists thercin that thc discharge tube with its contents is maintained at an opcrating tempcrature, which is optimum with rcspect to its efficicncy; a high light yield can thus be achieYed at a relatively low opcrating voltage or current consumption. Practical consideratians and trials have rcvealcd that thc energy costs amount to only about 33% of those cncountered with fluores-cent tubes, which are operated with al~crnating current w~th choke and starter.

`l~

2~514~7 Advantageously, the heater is realized by an ohmic heating resi~t~nce, which con-tacts the discharge tuhe by means of a thermal connection. This concept c~n ~e developed further in a particularly advantageous manner owing to the fact that the heater resistance is interposed in a current-limiting manner in the electric circuit S of the hot electrodes of the discharge tube and, in particular, is connected in series with the hot electrodes. In so doing, the ballast resistance, which as such is ab~o-lutely essential for every fluorescent lamp and which serves, among other purpose, to limit the current in the case of a direct current operation, is integrated struc-turally with the heater and can therefore fulfill two functions, namely, on the one hand, to selve as a ballast/current-limiting/series resistance and, on the other, to hcat the discharge tube and its contents.

Compared to atmospheric pressure, the discharge tube generally is under a higheror lower pressure (low-pressure, high-pressure and highest pressure lamps). An appropriate development of the invention takes this into account owing to the fact that thc heatcr, particularly thc hcating rcsistance, is constructcd as a hcating wire, which lies on the outer wall of the discharge tube. In order to attain a uniform, symmetrical tcmperature distribution within the discharge tube with such an arrange-mcnt, thc hcating wirc, pursuant to a further advantageous realization of thc invention, is shapcd or disposcd in such a manncr, that it extcnds along helicallincs over the wholc length of the tubular discharge tube.
., , In thc luminous operation of thc fluoresccnt lamp, the heating wire, which extends on thc outer surface of the discharge tubc, can interfere optically This is coun-tcred by a further inventive development, according to which a heat-inscnsitive filamcnt, wire or other strand, around which the heating wire is guided in helical fashion, is stretched from onc end of the discharge tube to the other. The filament, 205~447 at the same time, ~orms a core for the heating wire for its guidance and so stat i-lizes the mounting of the heating wire on the outer wall of the discharge tube.

A particularly advantageous further development of the invention consists therein that ;rhe filament and/or the discharge tube is surrounded by a transparent outer S enclosure of plastic or glass. Particularly when the filament with the heating wire coiled around it runs along the outside of the discharge tube, the outer enclosure forms an appropriate insulation against external environmental effects and serves for ;¦ additional stabilization and, at the same time, for increasing the safety and reli-ability.

On the other hand, if the heating wirc is to bc disposcd in the interior of the discharge tube, it is particularly advisable, for insulation against the discharging gas and, at the same time, for the mechanical stabilization and for prolonging the service life, to surround the filament and the heating wire on it with a rigid and/or insulating tube.

lS Duc ~o the invcntivc arrangement of thc heatcr, i~ is possihle to opcratc thc fluorcscent lamp with direct current, dcspite the polarizssion that takcs placc at thc same time. Consequently, it is advantagcous for thc imcntivc fluorcsccnt lamp toprovidc an altcrnating voltagc rectifier, which is couplcd with the hot clcctrodcs in thc discharge tubc and/or thc heater, in ordcr to supply them ~ith direct current ~or dircct-current opcration, the impedances causing inductivc, rcactive or wattless power, such as chokc coils for firing the gas discharge, are cancelled. Conscquently, , the problcm is raised of starting the gas discharge in the discharge tube with hot elec~rodes under a direct current voltage For this purpose, a firing network is 205~4~7 provided in a further ~levelopment of the invention. This firing network i~ c(~n-nected in series with one of the hot electrodes and consists of one or more stabi-lizing diodes and coupling and/or smoothing capacitors; these are arranged and designed in such a manner, that the firing network initiates the discharging process S and can stabilize the continuous discharge operation. Furthermore, it is coupled on the input side with the rectifier and/or the alternating voltage source. One realiza-tion of the firing networlc, which lies within the scope of the invention, lies therein tha~ it comprises two stabilizing diodes, which are connected in series and a capac-itor, which is connected in parallel to these diodes, this connection in series and parallel being connected on the input side with the rectifier output and on the output side with one of the hot electrodes. The stabilizing diodes serve to keep the electrical voltage of the hot electrode, which is connected in series, constant com-pared to the opposite, other hot eleclrode, while the smoothing capacitor decreases the residual waviness of the rectification of the alternating current network.

A particularly advantageous development of the invention to initiate the firing of the gas discharge consists therein that the (stabilizing) diode ncarcst to thc hot electrode is connected with its input terminal to a capacitor, which is designed as a differentiating element and is connected on its opposite side directly with the alternating current network. In the switching-on phase of the fluorescent lamp, this capacitor couples the applied alternating voltage over the stabiJizing diode with the hot elec~rode. Because of the differentiating properties of this capacitor, a current surge is brought about in the discharge tube. This is sufficient to get the gas diseharge going in the tube.

For realizing the rectifier, it is advisable to dispose four diodes in a bridge circuit 2S in a known manner. ~n alterna~ing current resistance is then connected in parallel 2051~g~7 with and at the input side of the bridge rectifier and/or one or more charging capacitors are connected in parallel with and at the output side of the bridge rectifier. As is well know, the charging capacitors serve to smoothen the outputvoltage of the rectifier in an integrating fashion; in addition, they have the extra-S ordina~y a~vantage that they initially act during the switching-on phase as short-circuiting current drains, until they are charged; during this time, the gas discharge-firing effect of the above-mentioned, differentiating coupling capacitor can develop without being impeded or impaired.

To achicvc an attractive appearance and ~I compact construction, a fluorescent tuhe ballast, comprising an optional alternating voltage rectifier and/or a firing network, is integrated structurally with particular advantage with the or in the lamp con-nection socket, which serves for bringing about electrical contact, and, in particular, is constructcd in one piece with this socket. The connecting socket can be provided as a scrcw base with a standard external thread for screwing into an appropriateholder, which is conncctcd with a powcr plug; on the other hand1 a power supply cable with plug can Icad dircctly into the screw base. An alternative possihiliq for accammodating thc fluoresccnt tube ballast consists of disposing it structurally in thc annular space boundcd by the inner discharge tubc and by the outer enclosurc surroundin& this tube.

Further charactcristics, dctails and advantages of the imcntion arisc out of thcfollowing description of preferred embodiments of the invention, as well as from the drawing, in which Figurc 1 shows the arrangemcnt of the fluorescent tubes and thc electronic circuit components associated with thcm, Z0514~7 Figure 2 shows a further development of the invemive fluorescent tube ~rrange-ment in a partially cut, longitudinal view, Figure 3 shows a truncated exterior ~icw of the end of the inventive fluorescent tube and Figure 4 shows a modified embodiment in a vicw corrcsponding to that of Figure 3.

Thc cssential parts of thc arrangcmcnt shown in Figurc 1 arc a convcntional, commercial onc-pin basc fluorcscent tube 1 with heatcr 2, as wcll as the altcrnating current rectifier circuit 3 and firing circuit 4. In thc cxamplc, the hcater 2 is constructed as a helical hesting wirc and disposcd so as to lic on the outer wall of the tube 5. llle one end of the hcating wirc k connected to thc negati~c terminal 6, which is led dircctly ou~ of thc rcctificr circuit 3 and the othcr cnd is connccted over a ter ninal jaw 7 with the connecting pin 8b of one of the two one-pin bases 9. The connccting pins 8 at cach cnd of thc fluoresccnt ~ubcs or of thc dischargc tube I change over in thc intcrior of thc lattcr into thc (not drawn) hot clectrodcs. Thc heating wire 2 spirally surrounds a filamcnt 10, which thus forrns an inncr guide corc of the hcating wire and is mounted on thc outcr wall at the cnd of the fluorcscent tub~e 1 averta1 from thc tcrminal jaw 7 by mcans of an adhcsivc joint 11 (drswn diagrammatically). Thc o~her, oppositc end of thc filament 10 is fastened within thc tcrrninal jaw 7, which in turn is fastencd by being clsmped around thc connccting pin 8. By thesc means, thc filamcnt 10 is placed under mechanical tension betwecn the cnds of the fluorescent tubc or thc discharge tube 1 and the filamcnt 10 can functinn as thc intcrnal guiding core for mechanical .
.
:-' .2~5~L7 .

stabilization of the position of the heating wire coil 2.

The connecting pin 8a, which lies at the end of the fluorescent tube 1 that is averted from the clamping jaw 7, is connected over an electrical connecting iine 12 with a positive terminal 13, which is led indirectly out of the rectifier circuit 3 ~y way of the ~Iring circuit 4. The rectifier circuit 3 is supplied at ~he input side from a 220 volt alternating current network, a load resistance RL being connected in parallel to the two output terrninals of the alternating current network (such as the phase conductor and the neutral conductor) in order to produce a defined input voltage. The rectifier 3 comprises the four diodes D~, D2, 1:~3 and D~" which are disposed in a known manner in a bridgc circuit. A charging capacitor CLI and CL2 jS connected in parallel with the positive and negative outputs of this bridge rec~ifier circuit 3, as well as with one of the output terminals of the alternating voltage source with 220 volt.

The negative output 6 is connected dircctly vith the heatcr 2. On the other hand, thc firing network 4 is dircctly connected in scrics with the output of the rectifier 3 with positive polarity. Thc firing network 4 has the two stabilizing diodes Ds and D6, which are disposcd in series and wi~h which a smoothing capacitor Ca is jointly connected-in parallel. Moreover, thc firing andl at the same time, stabilizing circuit 4 has a coupling capacitor C~, thc one terminal of which is connectcd directly with ., an output terminal of thc 22û volt alternating current source and the other terminal of which is connectcd directly with an input of one of the stabilizing diodes D5, D6, prefcrably with the stabilizing diode D6, which is disposed closest to the connecting pin 8a of the fluorescent tube 1. Suitable design values for the load resistance RL
arc 100 - 680 k~, for the two charging capacitors CLI alld CL2 2.2 ~LF, for the coupling capacitor CIY 0.082 ,~F and for the smoothing capacitor CG 0-1 ,uF. For 2US~4~7 the heating wire, a resistance coating of 600 Q/m has proven to be appropriate.

When the 220 volt alternating current source is switched on, the charging capacitors CL1 and CL2 must first of all still be charged; consequently, they function initially as short circuiting current drains. The current, flowing at the same time over the load S resistance RL. produces a corresponding voltage drop, which is differentiated by the coupling capacitor CK into a current surge or a current peak, which, ~y way of the stabilizing diode D6 that is connected in series, reaches the positive terminal 13 and, by way of the connecting line 12, the connecting pin 8a of the fluorescent tube.Thc energy, which is thus supplied to the nuorescent tube 1 or the discharge tube 1, is sufficient to fire the gas discharge process. When the charging capacitors CL~
and CL2 are largely charged at the end of their time constant, which is also affected by the load resistance RL. the voltage drop at the load resistance RL ;S diminishcd in such a manner, that the coupling capacitor CK loses its dctectablc effect and that thcrefore a uniform direct voltage exists between the connecting pins 8 at thc two lS oppositc ends of the fluorescent tube 1 and this voltage is suffciently stablc for continuous opcration.

According to Figure 2, the arrangement shown in Figure 1, comprising the fluorcs-ccnt tube 1! with thc heating wire 2, which is lying on the tluorcsccnt tube 1 and is coilcd in spiral fashion around thc filamcnt 10, is surroundcd b~ an outer en-closurc. In thc example drawn~ this outer cnclosure has the shapc of a (p~stic) tube, which is closed off at one end with a stoppcr 15 that is prcssed into forcc fit.
A basc housing 16 with a standard external thread 17 and a contact element 18 isslipp¢d onto the other end of the outer enclosurc 14. The extcrnal thrcad 17 andthe contact element 18, which is insulated from it, serve to connect a source ofaltcrnating current, as drawn in Figure 1. Moreover, the circuit componcnts that 2~s~ 7 are also shown in Figure 1, namely the rectifier 3 or the ~Iring circuit 4, which are optionally mounted on a printed circuit board, are accommodated within the base housing 16. According to Figure 3, the fluorescent lamp arrangement can be screwed with the internal thread (not shown) by means of its base housing 16 into S a conventional holder 19 for lamp or incandescent bulbs. A network cable 20 with plug 21 for the connection to a conventional receptacle leads from the holder 19.

Of course, it is also within thc scope of the invention to lead the networlc cable 20 with the plug 21 directly through the base housing 16 ~o the alternating currentrectificr 3, as shown in Figure l; if this is done, the extcrnal thread 1~ and the con~act clement 18, which together scr~e to form a closcd altcrnating current circuit, can be omittcd.
.
Thc embodiment of Figurc 4 diffcrs from thosc of Figures 2 and 3 owing to the fact that thc socket 16 is replaced directly by thc network plug 21, in which the ~forem tionod fluorescent lamp ballast can bo _mmodalod.

I

Claims

The embodiments of the invention in which an 6-14-1991 exclusive property or privilege is claimed are defined as follows.

1. A fluorescent lamp, particularly a mercury discharge lamp with a transparent discharge tube (1), a fluorescent lamp ballast and a lamp connection socket (16), which serves for establishing electrical contact with the network, charac-terized in what the fluorescent lamp ballast has a firing network (4) as well asan alternating current rectifier (3), which supplies direct current for continuous operation to the discharge tube (1) and to an ohmic heating wire (2), which extends along the discharge tube (1) and is in thermal contact with this tube (1) and in that the fluorescent lamp ballast is structurally integrated with thelamp connection socket (16).

2. The fluorescent lamp of claim 1, with a tubular discharge tube, lying upon the outer wall (5) of which the heating wire (2) extends, characterized in that the filament (10) is stretched from one end of the discharge tube (1) to the other.

3. The fluorescent lamp of claims 1 or 2, characterized by a transparent outer enclosure (14) of plastic or glass, which surrounds a filament (10) and/or the discharge tube (1).

4. The fluorescent lamp of one of the claims 1 to 3, characterized in that the filament (10), upon which, there is the heating wire (2), is surrounded by a rigid and/or insulating tube and is optionally disposed within the discharge tube (1).

5. The fluorescent lamp of one of the preceding claims, characterized by an alternating current rectifier (3), which is coupled with the hot electrodes (8) in the discharge tube (1) and/or the heater (2) in each case for supplying direct current.

6. The fluorescent lamp of claim 5, characterized by a firing network (4), whichis connected in series with the hot electrode (8), is formed from one or more stabilizing diodes (D5, D6) and coupling or smoothing capacitors (CK, CG), is designed for introducing and stabilizing the discharge process and coupled on the input side with the rectifier (3) and/or the alternating voltage source (220volt).

7. The fluorescent lamp of claim 6, characterized in that the firing network (4) has two stabilizing diodes (D5, D6) connected in series and a smoothing capacitor (CG), which is connected in parallel to these diodes, this in series/in parallelcircuit being connected on the input side with the rectifier (3) and on the output side with one of the hot electrodes (8a).

8. The fluorescent lamp of claim 7, characterized in that the diode (D6) closestto the hot electrode (8a) is connected over a coupling capacitor (CK), which is designed as a differentiating element, with the alternating current source (220 volt).

9. The fluorescent lamp of one of the claims 5 to 8, characterized in that the rectifier (3) is constructed as a diode bridge rectifier (D1-D4), with which, onthe input side an alternating current load resistance (RL) and/or, on the outputside, one or more charging capacitors arc connected in parallel.

10. The fluorescent lamp of one of the preceding claims, characterized in that the connecting socket (16) is constructed as a screw base with an external thread (17) and/or is provided with a mains cable and/or mains plug (20, 21).

11. The lamp of claim 3 and one of the subsequent claims, characterized in that a fluorescent lamp ballast comprising an optional alternating current rectifier (3) and/or a firing network (4) is disposed structurally between the outer enclosure(14) and the discharge tube (1).

12. The lamp of claim 3 and one of the preceding claims, characterized in that the discharge tube (1) has a straight, extended shape.