US2492575A - Safety starter circuit and unit - Google Patents

Description

l. S. JACOBSEN Dec. 27, 1949 Filed June 21, 1947 SAFETY STARTER CIRCUIT AND UNIT 2 Sheets-Sheet l L|NE VOLTAGE ATTO R N EYS l. S. JACOBSEN SAFETY STARTER CIRCUIT AND UNIT Dec. 27, 1949 Filed June 2l, 1947 2 Sheets--SheeiI 2 Patented Dec. 27, 1949 UNITED STATES PATENT OFFICE Industrial Electronics Corporation,

Newark,

N. J., a corporation of New Jersey Application June 21, 1947, Serial No. 756,186

Claims. 1

The present invention is concerned with safety starting units and with circuits incorporating the same for the protection of gaseous, electrical discharge devices such as fluorescent lamps of the hot cathode type.

It is among the objects of the invention to provide a unit of the above type which is relatively inexpensive, compact and economical in operation, requiring a minimum of parts and which lends itself for use with fluorescent lamps and the conventional xtures thereof as a replacement for glow starters of conventional type, which does not draw current when the lamp is functioning normally and which assures the prompt elimination of the intermittent flashing on and off of a defective lamp, regardless of reasonable variations in ambient temperature, thereby not only avoiding the annoyance of such hashing but also safeguarding the starter unit itself from the destructive effect of such intermittent starting.

Another object is to provide a safety circuit for a starter unit of the above type which operates dependably and promptly to preclude the application of starting current to a defective lamp, and to maintain the lamp from flashing after the first few starting impulses have been applied thereto, regardless of normal variations in ambient temperature and which automatically restores itself promptly to permit normal operation of a new lamp substituted for the defective one.

A feature of the invention is a heat responsive switch arm connected at one end in circuit between a control resistor and a safety resistor, the pair of resistors being placed in series with each other and with a glow switch starter, the electrodes of a gaseous electric discharge device and a ballast coil. In a preferred embodiment shown, the switch arm short circuits the safety resistor from the circuit, both when the lamp is operating normally and when the circuit is not energized, that resistor functioning only with a defective lamp. In response to a prolonged starting current through the control resistor caused by repeated attempts to start a defective lamp, the switch arm is displaced, thus removing the short circuit from the safety resistor to bring it into action at such time only. The heating effect of the safety resistor will thereupon positively move the switch arm without oating thereof until it short circuits the glow switch and the control resistor effectively to remove them .from the circuit. Continued current passing through the safety resistor which is preferably of high ohmic resistance, produces sufficient heat to retain the switch arm in deflected position and thus retain the short circuitA across the glow switch until the circuit is broken, thereby preventing the glow switch starter from starting or attempting'to start the fluorescent lamp.

In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention:

Fig. 1 is a circuit diagram showing an embodiment of the safety starter circuit,

Fig. 2 is a front elevational view of the starter unit showing only the casing in cross section,

Fig. 3 is a side elevational View, similar to Fig. 2,

Fig. 4 is a rear elevational View similar to Fig. 2,

Fig. 5 is a transverse cross sectional View taken along line 5-5 of Fig. 4, and

Fig. 6 is a view similar to Fig. 5 taken along line 6-6 of Fig. 4.

Referring now to the drawings, there is shown in the diagrammatic view of Fig. .1. a conventional gaseous electric discharge device I0 of the hot cathode type such as a iiuorescent lamp including a pair of electrodes II and I2 at opposite ends thereof. One of the mains I3 connected to electrode II has a ballast coil I4 in series therewith, while a switch I5 is shown in the other main I6, the latter being connected to electrode I2.

The starting circuit includes terminals 22 and 23 which are connected to electrodes il and I2 respectively of the lamp by leads I'I and I8. A starter I9 which preferably is of the glow switch type has one of its electrodes 3I connected to terminal 22 and the other electrode 3!! thereof to lead 44 of control resistor 43, the other lead IIB of which is connected to lead All of resistor 39, the other lead 4I oi which ilatter resistor is connected to terminal 23. Thus starter I3, resistor 43 and resistor 39 are connected in series between terminals 22 and 23. The xed end of a bi-metallic switch arm 32 is connected as shown between resistors 43 and 39, for its free end to be movable between the contact ends of contact leads 36 and 31, respectively, connected to contacts 22 and 23. The free end 35' of switch arm 32 normally engages the contact end of lead 3l, so that resistor 39 is normally short circuited.

When switch I5 is closed, the'line voltage will be applied across the electrodes II and I2 of the lamp and across terminals 22 and 23. As the applied voltage is at the outset insufficient to cause arcing of the lamp I0 but sufficient to cause glow switch starter I9 to ionize, current will ow through the circuit, establishing a magnetic neld in the ballast coil Ill, the collapse of which upon opening the circuit establishes the desired Voltage. The path of current through the circuit will be through main I 6, electrode I2, lead I8, terminal 23, contact arm 31, switch arm 32, lead fifi, resistor 43, lead 44 ,through the glowswitch .starter I9, terminal l'22, lead I'I,electrode `I I, ballast :coil I4 and main I3. The heat developed by the ionization of the glow switch I9 will bring the contacts 30, 3| thereof together and close the gap therebetween, thereby stopping the glow. As soon as the glow ceases, the bimetallic contact v3l in the glow switch will cool and deflect, thereby causing the contacts of the glow switch to separate. This will break the starting circuit through the electrodes II and I2 and the ballastcoil I4, causing the magnetic collapse and producing .the voltage to discharge through the circuit. AThis sudden impulse should -bridge the gap between the now heated electrodes `in 1the lamp `and 4start the arc, 'causing the Alamp to flight. Since the arc when once maintained requires voltage fless than 'that required vto @initiate Athe -glow discharge Ain 'the glow switch, the latter Awill 4remain out of action andthe starting circuit is broken due to the gap between'the-'contacts '38, '3l of glow switch 19. If jthe lamp is -in lvnormal condition, one or twocyc'les of the-glow switch fshould Ylight it.

At the same time ythat 'lthe `contacts 39, 'Irl of the glow switch are -cl'osed but before the lam-p .lighfts, heatis generatedlin1resistor243 which will be idissipatedito the bimetallic switch arm '32. IIf =thela'mp is defective, continuedfcyclesof :the .glow switch I9 will produce suiicient heat in the resistor =1l-3to causeswtc'h farm '32 to deect `tothe position indicated in dashes in Fig. l so that the :end 35 flthereof `iis moved .outfof .engagement with the contact 3l, thereby removing the sho'r't circuit about `resistor 39. That .resistor will 'fnow draw current, the circuit being through main IB, elec- .trode I2, lead I8, terminal 2.3, lead ^4'I, resistor 39, leads 4D and :46, resistor 43,.lead 44,glow switch .'-IfSiwhich is ionized, 'terminal '22,1lead I l; electrode "IfI, ballast coil I4 fand mai'n '-I3. VThe combined heat from resistors .39 and 4'3 will rcause lswitch arm-32 Cto be positively :deilected '.until iit :is *brought intov engagement' with :contact 36 A as shown in dot and dash lines 'in "Fig, 1, land i'short circuit glow switch :I9 rand 1resistor 43, fth'ereby v'effectively 'removing them from the circuit and thus placing resistor *se -directlyacross'flamp electrodes II and I2. Continued `passage of current `through lresistor`39 will produce sufficient heat to 'maintain the :end 35'01 'switch arm 32 'in `eng'agenc.ent with contact36, thus vretaining the short circuit lacross the vglow switch I9 andfresistor 43and effectively preventing theiluorescentlamp from starting,in asmuch as the vglow Vswitch starter is now :out of thecircuit. vlt-is apparentthatthe shortcircuiting of the -glow -switch starter I9 will occur Aii" the lamp does noti-ight after -a'ffew cycles. Thus the rapid 'destructionof Vthe Aglow switch t9, due to many repetitions of the `starting cycle cna defective lamp, is avoided. Shortly after the circuit is broken by the `opening 'of switch I5, or opening of circuit by lamp removal, resistor 39 willcool'and allow'switch r32 to re-vertto its normal position shown in Fl-ig. 1, in readiness for normal operation withareplacement lamp.

Resistor 43should have a relatively low `ohmic value, to have available .sufficient voltage across the opencontacts of `the `-glowswitch, to initiate and maintain-the glow discharge. In the embodimentherein, a .Nichromedresstor is used, illustratively of in the order of 15 ohms, which will determine the desired current flow. However, as it only requires a relatively small wattage to produce sufficient heat to maintain the switch arm 32 in deected position, resistor 39 which in the embodiment herein is of carbon composition, should be of high ohmic value in the order of .20,000 .ohms clamore. Thus when-the-glow switch .starter and resistor 43 are short cii'cuited by switch arm 32 when the lamp is defective, and resistor 39 is placed across the electrodes II and I2, resistor 39 will draw but little current and thus will use `but 'little power.

Among other advantages of the circuit is the .fact .that the instant the switch arm 32 disen- ,g'ages lcontact 37, 'the carbon resistor is cut into circuit to become heated for the sal'ety action 'to commence. 'That safety action is not interruptedfor an instant, but current evolving effective heat is passed through resistor 39 throughout the period that switch .arm 32 isin transit from contact 3? to contact't and thereafter. There is therefore no "danger of inhibiting the safety action on low ambient temperature as in a cold room for instance. 'Sufcient heat will be developed by the heating of the carbon resistor 39 to ensure `positive movement of the switch varm vand to'guardagainstthe switch arm floating between 'contact arms '3? and 36, as it might if the .safety action ibegan only when switch arm 32 had been delle'cted'all the way 'toasafety contact position.

Asafety starter unit incorporating Athe starting and safety controls of the circuit shown in Fig. l `and above described, is shown in Figs. 2 to v6 of the .drawingswherein the `numerals used in the circuit'diagram `of Fig. 'l are employed for corresponding elements. The unit which is connected across leads ll' 4and I8 from electrodes IgI and I2 respectively, comprises an insulating base 2`I `with two terminals '22 and 23 depending therefrom Aand 'a metal cover or cap 24 .having tabs A25 removably to secure it to base 2l. The cap '24 had van )insulating rliner 29 covering its side wall vand a yfurther insulating liner disk 21 for its top wall. 'In the unit is enclosed the insulating upstan'din'gpanel 28 4rigidly aflixed in the manner hereinafter set forth to terminal posts, 22 and 23 and having mounted on one side thereof a starter I9 which preferably is of the glow switchtype. v'Thisswitch maybe of conventional construction, involving a. ,glass tube 29 filled 'with noble gas, such as neon for instance, and having electrodes 39 and 3l, one of which is U-s'h'ape'd and Lof bimetallic material responsive to variations in temperature. The other components `of vthesafety starter unit are disposed on the 4side of panel'28 opposed to the glow switch starter I9 and comprise a bimetallic switch arm 32, preferably lin the 'form of a leaf which is secured near the lupper end thereof to .panel 28 by the laterally extending .arm .33 ,of a .metal clip`34, saidarmpressing'the end of switch arm 32 against the panel. Clip 34 has tabs 35 unitary therewith extending through andbent over rigidly to affix cit `to .the Ipanel 28. The switch .arm 32 Yextends vdownward the length of the vpanel and has a wire contact 35 at its end which .normally engages a contact bar 3l affixed atcne end Iby tabs .37 therefrom.

A Contact bar 36 .in juxtaposition fto Acontact bar 3.7 .and slightly spaced therefrom, is affixed at one end tothe panel'by tabs 39 vand connected to terminal .post 22. vContact bars 36 and .3-'I

straddle the wire Contact A35 of switch `arm 32. l

to said .panel and spacedl the wire contact 35 being normally in engagement with contact bar 31 and free to move between contact bars 36 and 31. The said contacts are preferably of silver or silver plated for low resistance and the inhibition of arcing.

Positioned alongside switch arm 32 is carbon resistor 39, one terminal wire 4|] of which is soldered to metal clip 34, while the opposite terminal wire 4I is soldered to the tab end 31 of contact arm 31 and passes through panel 28 to be connected to terminal 23 as at 42 to providea rigid support for one bottom corner of the panel.

Lead 41 of the glow switch starter I9 is soldered to the tab end 38 of contact arm 36 and passes through panel 28 to be connected to terminal 22 as at 41' to provide a rigid support for the other bottom corner of the panel while lead 48 of the glow switch starter I9 extends through an eyelet 45 affixed to the panel at the top thereof.

' Positioned near the upper end of switch arm 32 is Nichrome resistor 43, lead 46 thereof being soldered to metal clip 34 while lead 44 thereof extends through eyelet 45 and is soldered thereat to lead 48 of the glow switch starter I9. It will be understood that the spring tension of switch arm 32 is such as to maintain contact wire `35 thereof against contact arm 31 even at the highest temperature encountered in any place where a fluorescent lamp is normally installed or which is generated by the heat of a normally operating lamp. Thus it can be seen that the control resistance 43 serves the double function of determining the voltage across the glow switch starter I9 and of initiating the movement of the thermal switch arm 32 in the repeated attempts to start a defective lamp. The safety resistance 39 thereby put in circuit together with resistance 43 effectively move the thermal switch arm 32 to contact arm 36 for short circuiting the starter unit and its control resistance 43 and do so with a minimum of current which flows therethrough as long as the defective lamp remains in circuit. 'Ihe system and unit are therefore simple, economical or current and thoroughly reliable in action inasmuch as oating or hunting of the thermal switch arm 32 between its contact bars 36 and 31 is precluded, the thermal switch arm 32 remaining in its normal position as long as the controlled lamp is in order and once it leaves contact bar 36 it moves positively to the starter short circuiting position.

As many changes could be made in the above circuit and construction, and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. A safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes comprising a starting circuit for passing current through said electrodes in series, said circuit comprising a pair of resistors connected in series between said electrodes, a thermally responsive switch arm in proximity to both of said resistances and connected at one end therebetween, and a starter in the series circuit between the connected end of said switch arm and one of said electrodes, intermittently to interrupt said starting circuit, said switch arm becircuit across said safety resistor,

6 ing deflected by the heating of said resistors to short circuit said starter, thereby stopping the intermittent interruption of said starting circuit.

2. A safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes comprising a starting circuit for passing current through said electrodes in series, switch means intermittently to interrupt said starting circuit, a pair of resistors in series with said switch means and said starting circuit, and a heat responsive switch arm normally short circuiting one of said resistors, said switch arm being deilected by the heating of the second of said resistors during the operation of said switch means to remove the short circuit from the iirst of said resistors and place the latter in the circuit, said switch arm being further deflected by the continued operation of said switch means to short circuit the second of said resistors and said switch means, said first resistor evolving suiiicient heat to maintain said switch arm in denected position, thereby stopping the intermittent interruption of said starting circuit.

3. The circuit as claimed in claim 2 in which the means intermittently to interrupt said starting circuit comprises a starter of the glow switch type.

4. In a safety starting and operating circuit for a gaseous electric discharge device equipped with spaced electrodes, a starting circuit for passing current in series between said electrodes, means automatically to interrupt said circuit to strike an arc between said electrodes and means to preclude the sustained intermittent starting of a defective lamp, said latter means comprising a thermally operated switch arm normally in said starting circuit, a safety resistor in said starting circuit normally short circuited by said switch arm, a control resistor in said starting circuit normally in series with said switch arm, said switch arm being deflected by the heat evolved in said control resistor in the attempted starting of a defective lamp to remove the short the heat evolved by said safety resistor in the continued attempted starting of a defective lamp deflecting said switch arm further to short circuit said control resistor and said means automatically to interrupt said starting circuit, thereby preventing further attempts to start said lamp.

5. A safety starting and operating circuit for gaseous electric discharge devices equipped with spaced electrodes comprising a starting circuit for passing current through said electrodes in series, a pair of starting contacts in said starting circuit, a pair of heater means in said starting circuit, a heat responsive switch arm connected at one end between said pair of heater means and normally short circuiting one of said heater means, the second of said heater means evolving suiiicient heat in the attempted starting of a defective lamp for displacement of said switch arm to remove the short circuit across said first heater means, said first heater means evolving suicient heat in the continued attempt to start said lamp to displace said switch arm' further to short circuit said second heater means and said pair of starting contacts, said iirst heater means maintaining said switch arm in displaced condition as long as the circuit remains closed, thereby preventing further attempts to start said lamp.

6. A self contained safety starter unit for a gasecus electric device, said unit comprising a support base having a pair of terminal posts, an insulating panel rising therefrom, an eyelet affixed to said panel, a bi'metallic switch arm, a clip aiiixed to said panel and rigidly clamping one end of said switch arm thereagainst, a wire contact lat the free end of said switch arm, a pair of spaced contacts aiiixed to said panel in the path of movement of and straddling said wire contact, one of said spaced contacts being normally engaged by said wire contact, a resistor positioned in Vclose heat transfer relation to said switch arm at the aixed end thereof having one of its leads connected to said clip and the other `of its leads connected to said eyelet, a second resistor positioned alongside said switch arm having one of its leads connected to said normally engaged spaced con tact and to one of said terminal posts and the other of it leads aiiixed to said clip, a glow switch starter having a pair of contacts, one of its con- .tacts being connected to the other of said terminal posts and to the other of said spaced contacts, and the other contact of said starter being connected to said eyelet.

'7. A panel unit for a safety starter unit, said panel unit having a glow switch starter on one side thereof having a pair of contacts, a bimetal switch arm on the other side of said panel having a Contact end, a metal clip for said switch arm anixed to said panel and rigidly holding one end of said switch arm thereto, a resistor having a pair of leads and positioned in yclose heat transfer relation to the ailixed end of said switch arm, one of the leads from said resistor being connected to said metal clip and the other lead from said resistor being connected to one of the contacts of said starter, a contact bar affixed at one end to said panel and connected to the other contact of said starter, a second contact bar also aiiiXed at one end to said panel and adjacent to and spaced from said iirst contact bar, said contact bars being in the path of movement of said contact end, said contact end normally engaging said second contact bar and spaced from said iirst contact bar, a composition resistor positioned alongside said switch arm and having a pair of leads, one `of the leads being connected to said metal clip and the other of said leads being vconnected to said second contact bar.

8. A safety starter unit for a gaseous electric discharge device having a pair of spaced electrodes, said unit comprising a pair of terminals, a vIbimetal switch arm, a support therefor at one end thereof, a `pair of spaced contacts both in the path of movement of the outer end of said switch arm and straddling said outer end, one of said contacts being normally engaged by said outer end and the other of said contacts being normally spaced from said outer end, a pair of resistances each having a pair of leads, said resistances being in close heat transfer relation to said switch arm, one of said resistances having a lower ohmic value than the other, one of the leads from veach of said resistances being connected to said switch arm, the other lead of the resistance of higher ohmic value being connected to one of said terminals and to the normally engaged contact, a. glow switch starter having a pair of contacts, one of its contacts being connected to the vother end of the resistance of lower ohmic value and the -other of its contacts being connected to the other of said contacts of said pair of contacts and to the other terminal.

9. In a starting and operating circuit for gaseous electric discharge devices ,equipped with spaced electrodes, a starting circuit for passing current through said electrodes in series, said starting circuit including a pair of starter contacts, means automatically to open said contacts when the arc across the electrodes is struck, and to maintain them open while the arc exists, a thermally responsive arm in said circuit, a control resistor passing the starting current and generating the heat to deflect said arm to interrupt said starting circuit in the attempted starting of a defective lamp, a safety resistor normally out of circuit, said thermally actuated arm, when deiiected, connecting said safety resistor in `said starting circuit, said safety resistor deflecting'said arm further in the continued attempted starting of said defective lamp, and cutting said pair of starter contacts and said control resistor out of circuit, said safety resistor generating suiiicient heat to maintain said thermally responsive arm in deiiected position as long as the circuit remains closed.

10. The combination set forth in claim 9 in which said control resistor has a low ohmic resistance of from 10 to 20 ohms and said safety re-l sistor has a relatively high ohmic resistance of from 20,000 to 50,000 ohms.

IRWIN S. JACOBSEN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED vSTATES PATENTS

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