Electronically controlled magnetic fluorescent lamp ballast

An arrangement characterized by comprising:

• a) impedance means connected with a source of electric power and operative to provide a current-limited AC supply voltage across a pair of ballast terminals;
• the AC supply voltage being characterized by having a cycle period;
• b) gas discharge lamp means having a pair of lamp terminals and being connected with the ballast terminals by way of these lamp terminals;
• the lamp means being operative to exist in either of two states:
• i) a pre-ignition state during which no substantial amount of current flows through the lamp means;
• and ii) a post-ignition state during which a substantial amount of current does flow through the lamp means;
• the lamp means having a thermionic cathode with a pair of cathode terminals;
• and
• c) control means connected with the ballast terminals and operative to exist in either of two modes:
• i) a first mode existing throughout the pre-ignition state and during which the control means alternates between relatively brief periods of effectively constituting an open circuit and relatively long periods of effectively constituting a short circuit, while also during these relatively long periods providing cathode heating power to the thermionic cathode by way of the cathode terminals, each relatively brief period having a duration substantially longer than half the duration of said cycle period;
• and ii) a second mode existing throughout the post-ignition period and during which the control means effectively constitutes a continuous open circuit;
• and by being operative to:
• 1. provide cathode heating power for the cathode, thereby to cause the cathode to become hot and thereby operative to permit effective ignition of the lamp means;
• and
• 2. cause the lamp means to ignite during one of the relatively brief periods and thereby to enter the second state, the ignition taking place regardless of the particular moment in time at which this one relatively brief period starts.

An arrangement characterized by comprising:

• a) impedance means connected with a source of AC voltage and operative to provide a current-limited AC supply voltage across a pair of ballast terminals;
• b) gas discharge lamp means having a pair of lamp terminals and being connected with the ballast terminals by way of these lamp terminals;
• the lamp means being operative to exist in either of two states:
• i) a pre-ignition state during which no substantial amount of current flows through the lamp means;
• and ii) a post-ignition state during which a substantial amount of current does flow through the lamp means;
• and
• c) control means connected with the ballast terminals and operative to exist in either of two modes:
• i) a first mode existing throughout the pre-ignition state and during which the control means alternates between relatively brief periods of effectively constituting an open circuit and relatively long periods of effectively constituting a short circuit, while also during these relatively long periods providing cathode heating power to the thermionic cathode by way of the cathode terminals, this cathode heating power being provided in the form of a cathode voltage of frequency substantially higher than that of the AC supply voltage, the cathode heating power being provided by way of a frequency conversion means included as part of the control means;
• and ii) a second mode existing throughout the post-ignition period and during which the control means effectively constitutes a continuous open circuit;
• and by being operative to:
• 1. cause the thermionic cathode to become hot and thereby operative to permit effective ignition of the lamp means;
• and
• 2. cause the lamp means to ignite during one of the relatively brief periods and thereby to enter the second state.

An arrangement characterized by comprising:

• a) impedance means connected with a source of AC voltage and operative to provide a current-limited AC supply voltage across a pair of ballast terminals;
• b) gas discharge lamp means having a pair of lamp terminals and being disconnectably connected with the ballast terminals by way of these lamp terminals;
• the lamp means being operative to exist in either of two states:
• i) a pre-ignition state during which no substantial amount of current flows through the lamp means;
• and ii) a post-ignition state during which a substantial amount of current does flow through the lamp means;
• and
• c) control means connected with the ballast terminals and operative to exist in either of two modes:
• i) a first mode existing throughout the pre-ignition state as well as throughout any period when the lamp means may be non-connected with the ballast terminals, during which first mode the control means alternates between relatively brief periods of effectively constituting an open circuit and relatively long periods of effectively constituting a short circuit, and ii) a second mode existing only when the lamp means is connected and then only during the post-ignition period, during which the second mode the control means effectively constitutes a continuous open circuit.

An arrangement for powering a gas discharge lamp means having a pair of lamp terminals, comprising:

• a) impedance means connected with a source of AC voltage and operative to provide a manifestly current-limited AC supply voltage across a pair of ballast terminals, these ballast terminals being adapted for connection with the lamp terminals, the AC supply voltage having an open circuit magnitude that is so large as to represent a serious electric shock hazard to a person involved with connecting or disconnecting the lamp terminals with/from the ballast terminals;
• and
• b) control means connected in circuit with the impedance means and, whenever a lamp means is not connected with the ballast terminals, operative:
• i) to cause the magnitude of the voltage present across the ballast terminals to cyclically alternate between a relatively brief period of relatively high magnitude and a relatively long period of relatively low magnitude, and in such manner as to cause the relatively high magnitude to exist for no more than about 25 mill-seconds before being reduced to the relatively low magnitude;
• and functioning such that the voltage provided across the ballast terminals is prevented from representing a serious electric shock hazard to a person attempting to connect or disconnect the lamp means with/from the ballast terminals.

Control means for a gas discharge lamp ballast having a pair of ballast terminals, comprising:

• input terminals operative to connect with the ballast terminals;
• shorting means connected in circuit with the input terminals and conditionally operative:
• i) to cause an effective short circuit to occur between the input terminals, this short circuit occurring only after the magnitude of any voltage present between the input terminals has exceeded a pre-determined level for a first brief period of time;
• and ii) to cause the short circuit to disappear after a second brief period of time, this second brief period of time being at least ten times longer than the first brief period of time;
• such that the control means is operative to provide said effective short circuit across the input terminals whether or not a gas discharge lamp is connected across the ballast terminals.

A ballast means adapted:

• i) to be powered from the power line voltage of an ordinary electric utility power line, and ii) to operate a fluorescent lamp means, comprising:
• inductor means connected with the power line and operative to provide a current-limited AC voltage at a pair of ballast terminals, the magnitude of this current-limited AC voltage being large enough to permit rapid-start ignition of the fluorescent lamp means, the frequency of this current-limited AC voltage being the same as that of the power line voltage;
• connect means operable to connect a fluorescent lamp means across the ballast terminals, the fluorescent lamp means having a thermionic cathode;
• control means connected with the ballast terminals, the control means being operative to exist in either of two states:
• i) a first state wherein it constitutes a relatively low-magnitude impedance and wherein it provides electric heating power to the thermionic cathode, and ii) a second state where it represents a relatively high-magnitude impedance and wherein it does not provide electric heating power to the thermionic cathode;
• and
• starting aid electrode being:
• i) electrically connected with the power line, ii) positioned adjacent the lamp means, and iii) operative to constitute a starting aid for the lamp means;
• thereby to cause the lamp means to ignite in a rapid-start manner during a period when the control means exists in its second state, but only after having been preceded by a period during which the control means existed in its first state.