(19)
(11) EP 1 191 824 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
17.12.2003 Bulletin 2003/51

(43) Date of publication A2:
27.03.2002 Bulletin 2002/13

(21) Application number: 01660174.2

(22) Date of filing: 19.09.2001
(51) International Patent Classification (IPC)7: H05B 41/295
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 20.09.2000 FI 20002069

(71) Applicant: Helvar Oy Ab
00381 Helsinki (FI)

(72) Inventors:
  • Vihinen, Hannu
    02150 Espoo (FI)
  • Viljanen, Teijo
    02750 Espoo (FI)

(74) Representative: LEITZINGER OY 
Tammasaarenkatu 1
00180 Helsinki
00180 Helsinki (FI)

   


(54) Electronic ballast for fluorescent lamp


(57) The invention relates to an electronic ballast for a fluorescent lamp, the lamp load circuit being connected between the inverter power switch elements (S1, S2). The lamp load circuit comprises an inductor (LR) in a series connection with the lamp. Prior to the ignition of the lamp, the lamp load circuit also includes a capacitor (CR) in a series connection with the heating transformer primary winding (T1a), this series connection being in parallel with the lamp. The heating current is supplied to the lamp cathodes solely via the heating transformer secondary windings (T1b, T1c), whereby the heating current can be shut off by way of setting a switch element (S3) that is in parallel with the transformer primary winding (T1a) in an ON condition. The heating current may be controlled to a desired level by driving the switch (S3) ON and OFF with a pulse-width-controlled drive signal.






Search report