Low profile emergency ballast

• US 6,339,296 B1
• Filed: 05/11/2000
• Issued: 01/15/2002
• Est. Priority Date: 05/11/1999
• Status: Expired due to Term

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Bodine Company Incorporated
• Inventors: Goral, Jerzy M.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): TRAN, THUY V
• Application Number:
  US09/568,843
• Time in Patent Office: 614 Days
• Field of Search: 315/88, 315/86, 315/206, 315/209.R, 315/209.T, 315/219, 315/224, 315/276, 315/283, 315/360, 315/DIG.2, 315/DIG.5, 315/DIG.7
• US Class Current: 315/86
• CPC Class Codes: H05B 41/2853 against abnormal power supply conditions
• CPC Class Codes: H05B 41/2855 against abnormal lamp operating conditions

Abstract

An emergency ballast for a low profile fluorescent lamp fixture including an AC ballast including an end of lamp life shut down circuit. The emergency ballast includes a timing circuit which operates when AC power is restored to the lamp fixture after the fixture has operated for some period of time due to AC power failure. The timing circuit delays the application of AC power to the AC ballast for a given period of time (conveniently about 5 seconds) during the cessation of operation of the emergency ballast because of the restoration of AC power.

Claims

1. A flourescent lamp emergency ballast for selective addition to an operable fluorescent lamp having an AC ballast and an end of life shut-down circuit including delay circuit means for emergency operation of a fluorescent lamp with power supplied by a battery while power normally supplied to said fluorescent lamp from the internal AC ballast powered by AC power mains is interrupted, comprising:

inverter means for generating an alternating current from energy supplied by the battery including transformer means having two separate primary windings connected in parallel and a secondary winding, each of the primary windings inductively coupled to the secondary winding;

lamp starting means connected to said inverter means for operatively connecting said secondary winding in series with the fluorescent lamp for supplying a first alternating current as a starting current in said fluorescent lamp for a selected period of time;

lamp operating means connected to said inverter means for operatively connecting said secondary winding in series with the fluorescent lamp for supplying a second alternating current as an operating current to said fluorescent lamp for the period said AC power from the AC power mains is interrupted; and

timing means responsive to resumption of the supply of AC power by the AC power mains connected to switch means to delay the resumption of AC power to the AC ballast for a predetermined period of time during which said emergency ballast ceases supplying battery current to said inverter, said switch means being connectable intermediate the AC power mains and the AC ballast of the fluorescent lamp;

whereby said timing means responsive to the resumption of AC power delays the restarting of the fluorescent lamp by the AC ballast for a period of time subsequent to the operation of said inverter.

2. The emergency ballast of claim 1 wherein said inverter means includes two power transistors connected in push-pull relation to supply current to a center tap on the first of the two primary windings and the second of the two primary windings is connected to said transistors to cause alternate conduction thereof, whereby an alternating current is supplied by said transistors to said first primary winding.

3. The emergency ballast of claim 1 wherein said timing means responsive to the resumption of supply of AC mains power to the AC ballast includes a relay including open and closed switch contacts and a coil for operating the contacts, said coil being operably connected in series with a transistor, a capacitor connected to the bias of said transistor and charged by said inverter during the period said inverter means is generating alternating current, whereby on resumption of supply by AC power mains, said capacitor discharges through said transistor causing said transistor to conduct and supply current to said relay coil to operate said switch contacts.

4. An AC powered fluorescent lamp with an end of life shut-down circuit connectable to AC power mains, the lamp having an AC ballast for normal operation the fluorescent lamp and an emergency ballast for operation of the fluorescent lamp while power normally supplied to the AC ballast is interrupted, wherein the emergency ballast comprises;

inverter means for generating an alternating current from energy supplied by the battery including transformer means having two separate primary windings connected in parallel and a secondary winding, each of the primary windings inductively coupled to the secondary winding;

lamp starting means connected to said inverter means for operatively connecting said secondary winding in series with the fluorescent lamp for supplying a first alternating current as a starting current in said fluorescent lamp for a selected period of time;

lamp operating means connected to said inverter means for operatively connecting said secondary winding in series with the fluorescent lamp for supplying a second alternating current as an operating current to said fluorescent lamp for the period said AC power from the AC power mains is interrupted; and

timing means responsive to resumption of the supply of AC power by the AC power mains connected to switch means to delay the resumption of AC power to the AC ballast for a predetermined period of time during which said emergency ballast ceases supplying battery current to said inverter, said switch means being connectable intermediate the AC power mains and the AC ballast of the fluorescent lamp;

whereby said timing means responsive to the resumption of AC power delays the restarting of the fluorescent lamp by the AC ballast for a period of time subsequent to the operation of said inverter.

5. The fluorescent lamp of claim 4 wherein said timing means in the emergency ballast responsive to the resumption of supply of AC mains power to the AC ballast includes a relay including open and closed switch contacts and a coil for operating the contacts, said coil being operably connected in series with a transistor, a capacitor connected to the bias of said transistor and charged by said inverter during the period said inverter means is generating alternating current, whereby on resumption of supply by AC power mains, said capacitor discharges through said transistor causing said transistor to conduct and supply current to said relay coil to operate said switch contacts.

6. The fluorescent lamp of claim 5 wherein said switch contacts are disposed intermediate the AC ballast and the power connection of the fluorescent lamp to the AC mains.