Arrangement for igniting and a supplying gas and/or vapour discharge lamp

Claim 2

An ignition supply circuit for an electric discharge lamp of the type exhibiting a predetermined cold ignition voltage comprising, a first source of voltage of a value below the lamp cold ignition voltage, means for coupling said first voltage source across the lamp electrodes for supplying the operating current thereto during normal operation of the lamp, a second source of voltage of a value above the lamp cold ignition voltage, switching means for coupling the second voltage source across the lamp electrodes to ignite the lamp, means for sensing the condition of the lamp to cause said switching means to disconnect the second voltage source from the lamp when the lamp draws current from the first voltage source and to reconnect the second voltage source to the lamp in the event the lamp is deenergized due to a failure of the first voltage source thereby to supply an uninterrupted current to the lamp from said second voltage source for a given period of time subsequent to the failure of the first voltage source.

Claim 3

A circuit as claimed in claim 1 wherein the first voltage source comprises an alternating voltage source and the second voltage source comprises a direct voltage source and a DC-AC converter supplying an alternating current frequency of 1,000 Hz or more and connected between the terminals of the direct voltage source and the lamp electrodes.

Claim 4

A circuit as claimed in claim 1 wherein said sensing means is included in said coupling means and comprises a relay winding responsive to the supply current from said first voltage source, said relay having a normally closed contact in a lead provided between one terminal of the second voltage source and a lamp electrode whereby the contact is opened when a given current flows through the relay winding.

Claim 5

A circuit as claimed in claim 1 wherein said coupling means includes a first switch connected between a terminal of the first voltage source and a lamp electrode and said switching means includes a second switch connected between a terminal of the second voltage source and a lamp electrode and coupled to said first switch so that said switches open and close together in synchronism.

Claim 6

A circuit as claimed in claim 1 wherein said switching means includes a normally closed switch contact connected between a terminal of the second voltage source and a lamp electrode, a timing device connected across said second voltage source for controlling the operation of said switch contact so as to open same at a given time after the second voltage source is applied to the lamp, said given time being greater than the normal ignition time for the lamp.

Claim 7

A circuit as claimed in claim 5 wherein the lamp further exhibits a predetermined hot ignition voltage of a value such that the voltages applied to the lamp from said first and second voltage sources are lower than said hot ignition voltage of the lamp, said timing device further comprising a test section which is activated when the voltage of the first voltage source is once again available after a failure thereof and upon the operation of said switch contact which occurs after the lapse of said given time, said test section including means for intermittently connecting the second voltage source to the lamp during the time said switch contact is open.

Claim 8

A circuit as claimed in claim 1 wherein said sensing means is arranged in the supply circuit so as to respond to the lamp current supplied by said first voltage source and so as to be substantially non-responsive to the lamp current supplied by said second voltage source.

Claim 9

An ignition supply circuit for an electric discharge lamp comprising, a first source of low frequency AC voltage of a value below the lamp ignition voltage but of a value sufficient to maintain the flow of normal lamp operating current subsequent to ignition, a second source of high frequency AC voltage of a value above the lamp ignition voltage, switching means for simultaneously connecting said first and second voltage sources across the lamp electrodes whereby the lamp is ignited by said second voltage source whereupon the first voltage source supplies the normal operating current to said lamp, second switching means responsive to the lamp current supplied by said first voltage source for opening the circuit between tHe second voltage source and the lamp when said current flows and to close the circuit between the second voltage source and the lamp when said current drops below a given value sufficient to maintain the flow of lamp current, whereby the second voltage source supplies a reduced operating current to said lamp.

Claim 10

An ignition supply circuit for an electric discharge lamp comprising, a first source of low frequency AC voltage of a value below the lamp ignition voltage but of a value sufficient to maintain the flow of normal lamp operating current subsequent to ignition, a second source of high frequency AC voltage of a value above the lamp ignition voltage, switching means for simultaneously connecting said first and second voltage sources across the lamp electrodes whereby the lamp is ignited by said second voltage source whereupon the first voltage source supplies the normal operating current to said lamp, second switching means responsive to the lamp current supplied by said first voltage source for opening the circuit between tHe second voltage source and the lamp when said current flows and to close the circuit between the second voltage source and the lamp when said current drops below a given value sufficient to maintain the flow of lamp current, whereby the second voltage source supplies a reduced operating current to said lamp.

Claim 11

A circuit as claimed in claim 8 wherein said second voltage source comprises a source of DC voltage coupled to the input of a DC-AC converter via a part of said switching means and the output of said converter is directly connected across the lamp electrodes, and said second switching means comprises a current sensing element in series with said first voltage source and the lamp and having a switching contact connected between a terminal of said DC voltage source and one input terminal of said converter.

Claim 12

A circuit as claimed in claim 9 further comprising a timing device connected across the terminals of said DC voltage source via said switching contact and having a normally closed contact connected in series with a terminal of the DC voltage source and an input terminal of the converter whereby activation of said timing device after a given time period opens said normally closed contact to deenergize the converter.