US 4,392,081 AGranted

Lighting unit

AssigneeGeneral Electric Company

InventorsThomas A. Brown, William Peil

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Abstract

A lighting unit is described utilizing an energy efficient metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source producing light when the arc lamp is being started. The lighting unit is designed as a more efficient replacement for the incandescent lamp. The lighting unit includes means for conversion of 60 hertz ac to dc, and a dc energized operating network, including a ferrite transformer and an intermittently operated switching transistor serially connected with a load consisting of the filament or the arc lamp, or both, to which regulated output power is provided. The operating network produces an output with minimum dissipation adapted to each operating state of the arc lamp, including the provision of a high ignition potential, adequate power for the lamp during the glow to arc transition, warm-up and ballasting. In addition, while the arc lamp is being started, the operating network provides power for lighting the standby filament.

Claims26

Dependent claims

A lighting unit comprising:

A. a dc power supply having two output terminals,
B. a filamentary lamp and an arc lamp,
C. an operating network comprising:
(1) a transformer having
(a) a core of substantially linear magnetic material forming a first, main magnetic path, aperture means defining a second magnetic path lying within said main magnetic path of lower reluctance than said main magnetic path,
(b) a first and a second power winding coupled to said main magnetic path, current flow in either power winding generating flux which has one sense in one segment and an opposing sense in a second segment of said second magnetic path, and
(c) flux level dependent control means comprising a primary feedback winding and a secondary feedback winding passing through said aperture means and coupled to said second magnetic path,
(2) a normally nonconductive switching transistor connected to intermittently complete a current path through said primary feedback winding between one said supply output terminal and a node;
said secondary feedback winding being coupled across the input electrodes of said transistor for application of an initial conduction aiding feedback after transistor turn-on, continuing until one segment of said magnetic path becomes saturated, and a conduction inhibiting feedback thereafter, returning said transistor to a nonconductive state after a certain ON time,
(3) a primary power circuit for operating said filamentary lamp comprising said first power winding and said filamentary lamp in series, connected between said node and the other said supply output terminal,
(4) a secondary power circuit for starting and operating said arc lamp comprising said second power winding and said arc lamp connected in series between said first node and said other supply output terminal, said second power winding providing transformed starting potentials when said primary circuit is active,
(5) current maintenance means connected in circuit with said power windings for allowing current flow in said power windings during the transistor OFF time,
(6) switching means responsive to the state of said arc lamp for inactivating said primary power circuit when the arc lamp is warmed up, and
(7) means for repetitively turning on said switching transistor.

11 more elements

In a lighting unit having an incandescible filament and an arc lamp which are both to be energized from a dc source, the combination comprising:

(a) a switching device,
(b) means for controlling said device to turn it on and off during successive, alternate time periods,
(c) a series conduit connectable across said dc source and including two serially connected portions,
1. a first portion including said switching device,
2. the second portion including first and second parallel paths,
(d) said first parallel path including said filament,
(e) said second parallel path including said arc lamp, and
(f) means responsive to current flow through said first path during the on periods of said device for inducing high voltage pulses in said second path, thereby to aid in ignition of an arc within said lamp, said means (f) further including
first and second inductively coupled windings serially connected respectively with said filament and arc lamp and forming series components respectively within said first and second parallel paths, the sense of said windings being such that increasing current flow from said dc source through said switching device, first winding and filament induces a voltage in said second winding with a first polarity tending to create anode-to-cathode current in the arc lamp.

6 more elements

In a lighting unit which includes

(a) a high pressure metal vapor arc lamp,
(b) an incandescible filament,
(c) a source of dc voltage,
(d) a ferrite core transformer having a first power winding on the core and first and second control windings coupled together and associated with the core to detect the onset of a predetermined degree of core saturation,
(e) a unidirectional semiconductor switching device having main electrodes and a control electrode with said main electrodes, said first control winding, said power winding, and said arc lamp being connected in series across said dc source, the second control winding being coupled across said control electrode and one of said main electrodes, and
(f) means for intermittently turning on said switching device, whereby the first control winding current induces first regenerative and then degenerative feedback signals to the control electrodes to turn off that device,
the improvement which comprises in combination
(1) a second power winding on said core inductively coupled to said first power winding,
(2) a controllable switching unit,
(3) means connecting the series combination of said second power winding, said filament and said switching unit in parallel with the series combination formed by said first power winding and said lamp, thereby to form two parallel paths each in series with said switching device and said dc source,
(4) said two power windings being sized and wound with senses to constitute means for inducing high voltage pulses in said first power winding in response to current pulses flowing through said second power winding which excite said filament to incandescence when said unit is conductive, whereby high voltage is applied to said arc lamp to start the latter, and
(5) means, normally making said unit (30) conductive, but responsive to current flow through said first power winding when the arc lamp reaches a warm-up or run condition, for making said unit non-conductive.

9 more elements

Dependencies are inferred from the claim text.