# US 4,398,128 A · Method and circuit arrangement for heating and igniting as well as controlling or regulating the light flux of low-pressure gas-discharge lamps > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,128 A - Document ID: US4398128A - Status: Granted - Kind: A - Application number: 06/340,747 - Filed: 1982-01-19 - Granted: 1983-08-09 - Earliest claimed: 1981-01-20 - Assignees: Brown, Boveri & Cie AG - Inventors: Gerhard Wollank - Web page: https://patentgrep.com/patent/US4398128A ## CPC - H05B 41/2981: {for protecting the circuit against abnormal operating conditions} - Y10S 315/02: High frequency starting operation for fluorescent lamp - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract Method for heating and igniting as well as controlling or regulating the light flux of low-pressure gas-discharge lamps, including a ballast having an inverter for generating an ac voltage at inverter output terminals from a dc voltage generated from an ac supply network by rectifiers, the ac voltage having a frequency higher than line frequency, the ballast including an L-C circuit having a capacitor and a first choke connected between one of the inverter output terminals and a lamp, the lamp being in turn connected to another of the inverter output terminals, a second choke shunted across the lamp, the charge of the capacitor being constantly reversed by the inverter with controllable frequency, which comprises changing the inverter frequency in accordance with the desired light flux with constant ac voltage amplitude at the outputs of the inverter, tuning the frequency, voltage, capacitor, first choke and second choke to each other, circulating substantially the required heating current through heating coils of the lamp at low frequency before the lamp is ignited, decreasing the heating current at rising frequency until substantially 40% of the rated light flux of the lamp is reached after the lamp is ignited, and decreasing the heating current to less than 25% of its initial value as the frequency continues to rise until the rated light flux of the lamp is reached, and an apparatus for carrying out the method. ## Claims ### Claim 1 Method for heating and igniting as well as controlling or regulating the light flux of low-pressure gas-discharge lamps, including a ballast having an inverter for generating an ac voltage at inverter output terminals from a dc voltage generated from an ac supply network by rectifiers, the ac voltage having a frequency higher than line frequency, the ballast including an L-C circuit having a capacitor and a first choke connected between one of the inverter output terminals and a lamp, the lamp being in turn connected to another of the inverter output terminals, a second choke shunted across the lamp, the charge of the capacitor being constantly reversed by the inverter with controllable frequency, which comprises changing the inverter frequency in accordance with the desired light flux with constant ac voltage amplitude at the outputs of the inverter, tuning the frequency, voltage, capacitor, first choke and second choke to each other, circulating substantially the required heating current through heating coils of the lamp at low frequency before the lamp is ignited, decreasing the heating current at rising frequency until substantially 40% of the rated light flux of the lamp is reached after the lamp is ignited, and decreasing the heating current to less than 25% of its initial value as the frequency continues to rise until the rated light flux of the lamp is reached. ### Claim 2 (depends on 1) Method according to claim 1, which comprises keeping the frequency constant at a given low value for a given time span after turning on the ballast until the heating coils reach their required temperature, and subsequently increasing the frequency to a value corresponding to the desired light flux. ### Claim 3 (depends on 1) Circuit for carrying out a method for heating and igniting as well as controlling or regulating the light flux of low-pressure gas-discharge lamps according to claim 1, each lamp having two heating coils each having two terminals, comprising an inverter having output terminals for converting a dc voltage into an ac voltage of higher frequency at said output terminals, said inverter including two semiconductor switches receiving the dc voltage and being connected together in series and two antiparallel connected diodes each being respectively connected to one of said switches, one of said inverter output terminals being connected to one terminal of one coil of a lamp, at least one series circuit for increasing lamp current through the lamp with increasing frequency and for decreasing heating current through the heating coils of the lamp, each of said at least one series circuit including a first choke, and a capacitor connected in series between another of said inverter output terminals and one terminal of the other coil of the lamp, a second choke shunted across the other terminals of the coils of the lamp, and at least one frequency generator connected to said inverter for generating an ac ignition pulse voltage as a function of a given desired light flux for alternately switching said switches on and off. ### Claim 4 (depends on 3) Circuit according to claim 3, wherein said semiconductor switches are thyristors and said at least one frequency generator is in the form of two ignition pulse generators respectively forming and delivering the ac ignition pulse voltage as ignition pulses to one of said thyristors, each of said ignition pulse generators including a decoupling diode separating positive and negative parts of the ac ignition pulse voltage, a unijunction transistor having a power circuit and a resistor and a capacitor connected to said decoupling diode, and an ignition transformer having a primary winding connected to the power circuit of said unijunction transistor, and a secondary winding connected to said respective thyristor for furnishing ignition pulses thereto formed from the ac ignition pulse voltage. ### Claim 5 (depends on 4) Circuit according to claim 4, wherein each of said ignition transformers has another secondary winding, and including two parallel-connected RC-members each being connected between one of said other secondary windings and said thyristor connected to said other respective transformer. ### Claim 6 (depends on 4, 5) Circuit according to claim 4 or 5, wherein said respective thyristor and antiparallel-connected diode are in the form of backward conducting thyristors. ### Claim 7 (depends on 3, 4) Circuit according to claim 3 or 4, wherein said first choke is split into two choke parts, one of said choke parts being disposed upstream of the lamp and the other being disposed downstream thereof. ### Claim 8 (depends on 3, 4) Circuit according to claim 3 or 4, wherein said first choke has two windings, one of said windings being disposed upstream of the lamp and the other being disposed downstream thereof. ### Claim 9 (depends on 3, 4) Circuit according to claim 3 or 4, wherein at least one other lamp is connected in series with the first-mentioned lamp, and said second choke is split into two choke parts, each one of said choke parts being shunted across a respective one of the lamps. ### Claim 10 (depends on 3, 4) Circuit according to claim 3 or 4, wherein at least one other lamp is connected in series with the first-mentioned lamp, and said second choke includes a plurality of windings, each one of said windings being shunted across a respective one of the lamps. ### Claim 11 (depends on 3, 4) Circuit according to claim 3 or 4, including a potentiometer for setting a desired light flux of the lamp, and an integrating control connected to said potentiometer and to said frequency generator for driving said frequency generator with a defined acceleration curve. ### Claim 12 (depends on 11) Circuit according to claim 11, wherein said frequency generator is in the form of a voltage-controlled pulse generator forming voltage blocks of alternating polarity and a pulse width inversely proportional to the frequency. ### Claim 13 (depends on 3, 4) Circuit according to claim 3 or 4, including a light-sensitive component for measuring actual light flux of the lamp, and an integrating control connected to said light-sensitive component and said inverter for comparing desired and actual light flux. ### Claim 14 (depends on 3, 4) Circuit according to claim 3 or 4, including a rectifier for receiving line voltage and converting the line voltage into the dc voltage, a power input filter connected to said rectifier, an uncontrolled diode bridge connected to said rectifier, a dc voltage smoothing member connected to said diode bridge, a current measuring device connected to said diode bridge for measuring actual dc durrent, a dc voltage measuring device connected to said diode bridge for measuring actual dc voltage, and a direct current switch connected to said diode bridge for inhibiting the direct current upon the occurence of any one of undervoltage, excess current and short circuit. ### Claim 15 (depends on 14) Circuit according to claim 14, wherein said direct current switch is in the form of a further thyristor having a control electrode for turning said further thyristor on and off. ### Claim 16 (depends on 14) Circuit according to claim 14, including switch prevention means connected to said direct current switch for preventing said direct current switch from being turned on again for a given time span after having been turned off. ### Claim 17 (depends on 16) Circuit according to claim 16, including means connected between said switch prevention means and said direct current switch for preventing further starting attempts after a given number of unsuccessful attempts at again turning on said direct current switch. ### Claim 18 (depends on 3) Circuit according to claim 3, including means for locking disturbing variables of the actual dc voltage on to said frequency generator for increasing the frequency with decreasing dc voltage and for decreasing the frequency with increasing dc voltage.