Lamp failure indicating apparatus

Claim 2

In a light system having a first lamp array connected in series with a power source and a first resistor and a second lamp array connected in series with the power source and a second resistor, each lamp array comprising a certain number of parallel connected lamps having similar impedances, the ratio of the impedance of the first lamp array to the impedance of the first resistor being the same as the ratio of the impedance of the second lamp array to the impedance of the second resistor, apparatus for indicating when a lamp in either of the lamp arrays has failed comprising, in combination, a differential comparator for comparing the voltage across each of the lamp arrays and generating first and second signals having relative magnitudes related to the difference between the voltages compared, the first and second signals being equal when the monitored voltages are equal and unequal when the monitored voltages are unequal, a full wave detector that is responsive to the first and second signals for generating a certain control signal only when the first and second signals are unequal, the control signal being other than the certain control signal when the first and second signals are equal, an indicator device for indicating that one of the lamps has failed, and an output amplifier that is responsive to the control signal for effecting an indication by the indicator device that a lamp has failed whenever the full wave detector generates the certain control signal.

Claim 3

In a light system having a first lamp array connected in series with a power source and a first resistor and a second lamp array connected in series with the power source and a second resistor, each lamp array comprising a certain number of parallel connected lamps having similar impedances, the ratio of the impedance of the first lamp array to the impedance of the first resistor being the same as the ratio of the impedance of the second lamp array to the impedance of the second resistor, apparatus for indicating when a lamp in either of the lamp arrays has failed comprising, in combination, a differential comparator comprising first and second matched diodes having their respective anodes connected to sample the voltage across the respective first and second lamp arrays, first and second matched amplifiers each having a control terminal and input and output terminals between which a controlled current path is defined, the control terminals of the respective first and second amplifiers being connected to the cathodes of the respective first and second diodes and the input terminals of the respective first anD second amplifiers being connected to the anodes of the respective second and first diodes, and first and second biasing impedances connected in series with the output terminals of the respective amplifiers; means for providing a predetermined load in series with each of the diodes whereby a predetermined potential difference is established across each of the diodes, the biasing impedances being selected to effect operation of the amplifiers so as to establish equal potentials on their output terminals when all of the lamps are operative and unequal potentials on their output terminals when a lamp has failed; detector means responsive to the potentials on each of the output terminals for generating a certain output signal when said potentials are unequal; an indicator device for indicating failure of a lamp in either of the lamp arrays; and means responsive to the detector means for effecting an indication by the indicator device that a lamp has failed when the detector means generates the certain output signal.

Claim 4

In a light system having a first lamp array connected in series with a power source and a first resistor and a second lamp array connected in series with the power source and a second resistor, each lamp array comprising a certain number of parallel connected lamps having similar impedances, the ratio of the impedance of the first lamp array to the impedance of the first resistor being the same as the ratio of the impedance of the second lamp array to the impedance of the second resistor, apparatus for indicating when a lamp in either of the lamp arrays has failed comprising, in combination, a differential comparator comprising first and second matched diodes having their respective anodes connected to sample the voltage across the respective first and second lamp arrays, first and second matched amplifiers each having a control terminal and input and output terminals between which a controlled current path is defined, the control terminals of the respective first and second amplifiers being connected to the cathodes of the respective first and second diodes and the input terminals of the respective first anD second amplifiers being connected to the anodes of the respective second and first diodes, and first and second biasing impedances connected in series with the output terminals of the respective amplifiers; means for providing a predetermined load in series with each of the diodes whereby a predetermined potential difference is established across each of the diodes, the biasing impedances being selected to effect operation of the amplifiers so as to establish equal potentials on their output terminals when all of the lamps are operative and unequal potentials on their output terminals when a lamp has failed; detector means responsive to the potentials on each of the output terminals for generating a certain output signal when said potentials are unequal; an indicator device for indicating failure of a lamp in either of the lamp arrays; and means responsive to the detector means for effecting an indication by the indicator device that a lamp has failed when the detector means generates the certain output signal.

Claim 5

A light system comprising, in combination, first and second lamp arrays, each lamp array including at least one grounded lamp; a power source having a grounded terminal; first and second resistors connecting the respective first and second lamp arrays in series with the power source so as to connect each lamp in each lamp array in parallel with the other lamps in the same lamp array, the ratio of the impedance of the first lamp array to the impedance of the first resistor being the same as the ratio of the impedance of the second lamp array to the impedance of the second resistor, the resistances of the lamps in each lamp array being equal and very much greater than the resistor resistances whereby the current through each lamp effects a predetermined voltage drop across the resistor in series therewith; first and second diodes having their respective anodes connected to the respective junctions between the first resistor and the first lamp array and the second resistor and the second lamp array for partaking of the voltage across each of the lamp arrays; first and second controlled amplifiers each having control, input, and output terminals, the control terminals of the respective first and second amplifiers being connected to the cathodes of the respective first and second diodes and the input terminals of the respective first and second amplifiers being connected to the anodes of the respective second and first diodes; first and second biasing impedances connected in series with the output terminals of the respective first and second amplifiers whereby the voltages on the output terminals are responsive to the conductivity of the respective amplifiers; means for drawing a predetermined current through the diodes so as to effect a predetermined voltage drop across each of the diodes of sufficient magnitude to render the amplifiers partially conductive, the magnitude of the biasing impedances being selected when all of the lamps are operative so that each of the amplifier output terminals are at a certain potential whereby failure of one of the lamps effects a change in the conductivity of the amplifiers and a corresponding difference in the potential on the output terminals of the amplifiers; a detector for generating a certain control signal when the output terminals are at different potentials, the detector including third and fourth controlled amplifiers each having control, input, and output terminals, the control terminals of the third and fourth amplifiers partaking of the potentials on the output terminals of the respective first and second amplifiers and the input terminals of the third and fourth amplifiers partaking of the potentials on the output terminals of the respective second and first amplifiers, the output terminals of the third and fourth amplifiers being connected so as to provide a common terminal at which the control signal is generated, equal potentials on the output terminals of the first and second amplifiers biasing the third and foUrth amplifiers to a first state of conduction in which they generate a first control signal on the common terminal and unequal potentials on the output terminals of the first and second amplifiers biasing the third and fourth amplifiers to a different conductive state in which they generate the certain control signal on the common terminal; an indicator device for indicating failure of a lamp; and means responsive to the certain control signal for effecting an indication by the indicator device that a lamp has failed when the detector generates the certain control signal.

Claim 6

A light system comprising, in combination, first and second lamp arrays, each lamp array including at least one grounded lamp; a power source having a grounded terminal; first and second resistors connecting the respective first and second lamp arrays in series with the power source so as to connect each lamp in each lamp array in parallel with the other lamps in the same lamp array, the ratio of the impedance of the first lamp array to the impedance of the first resistor being the same as the ratio of the impedance of the second lamp array to the impedance of the second resistor, the resistances of the lamps in each lamp array being equal and very much greater than the resistor resistances whereby the current through each lamp effects a predetermined voltage drop across the resistor in series therewith; first and second diodes having their respective anodes connected to the respective junctions between the first resistor and the first lamp array and the second resistor and the second lamp array for partaking of the voltage across each of the lamp arrays; first and second controlled amplifiers each having control, input, and output terminals, the control terminals of the respective first and second amplifiers being connected to the cathodes of the respective first and second diodes and the input terminals of the respective first and second amplifiers being connected to the anodes of the respective second and first diodes; first and second biasing impedances connected in series with the output terminals of the respective first and second amplifiers whereby the voltages on the output terminals are responsive to the conductivity of the respective amplifiers; means for drawing a predetermined current through the diodes so as to effect a predetermined voltage drop across each of the diodes of sufficient magnitude to render the amplifiers partially conductive, the magnitude of the biasing impedances being selected when all of the lamps are operative so that each of the amplifier output terminals are at a certain potential whereby failure of one of the lamps effects a change in the conductivity of the amplifiers and a corresponding difference in the potential on the output terminals of the amplifiers; a detector for generating a certain control signal when the output terminals are at different potentials, the detector including third and fourth controlled amplifiers each having control, input, and output terminals, the control terminals of the third and fourth amplifiers partaking of the potentials on the output terminals of the respective first and second amplifiers and the input terminals of the third and fourth amplifiers partaking of the potentials on the output terminals of the respective second and first amplifiers, the output terminals of the third and fourth amplifiers being connected so as to provide a common terminal at which the control signal is generated, equal potentials on the output terminals of the first and second amplifiers biasing the third and foUrth amplifiers to a first state of conduction in which they generate a first control signal on the common terminal and unequal potentials on the output terminals of the first and second amplifiers biasing the third and fourth amplifiers to a different conductive state in which they generate the certain control signal on the common terminal; an indicator device for indicating failure of a lamp; and means responsive to the certain control signal for effecting an indication by the indicator device that a lamp has failed when the detector generates the certain control signal.

Claim 7

In a light system having a grounded lamp connected in series with a grounded power source and a resistor whereby current through the lamp effects a predetermined voltage drop across the resistor, apparatus for indicating failure of the lamp comprising, in combination, a differential comparator for monitoring the voltage across the resistor and for generating first and second signals indicative of the operativeness of the lamp, the differential comparator including first and second matched diodes having their anodes connected to the respective terminals of the resistor, the anode of the first diode being connected to the resistor terminal that is connected to the lamp and the anode of the second diode being connected to the other resistor terminal, first and second controlled amplifiers each having control, input, and output terminals, the control terminals of the respective first and second amplifiers being connected to the cathodes of the respective first and second diodes and the input terminals of the respective first and second amplifiers being connected to the anodes of the respective second and first diodes, and first and second impedances connecting the respective output terminals of the respective first and second amplifiers to a point of reference potential whereby the first and second signals are generated on the output terminals of the respective first and second amplifiers, the first and second signals being equal when the lamp is operative and unequal when the lamp is inoperative; a detector that is responsive to the first and second signals and is effective to generate a certain control signal when the first and second signals are unequal, the detector including a third controlled amplifier having control and input terminals connected to the output terminals of the respective first and second amplifiers and an output terminal on which is generated the control signal; an indicator device for indicating that the lamp has failed; and an output amplifier that is responsive to the control signal and effective when the certain control signal is generated to cause the indicator device to indicate that the lamp has failed.

Claim 8

In a light system having a grounded lamp connected in series with a grounded power source and a resistor whereby current through the lamp effects a predetermined voltage drop across the resistor, apparatus for indicating failure of the lamp comprising, in combination, a differential comparator for monitoring the voltage across the resistor and for generating first and second signals indicative of the operativeness of the lamp, the differential comparator including first and second matched diodes having their anodes connected to the respective terminals of the resistor, the anode of the first diode being connected to the resistor terminal that is connected to the lamp and the anode of the second diode being connected to the other resistor terminal, first and second controlled amplifiers each having control, input, and output terminals, the control terminals of the respective first and second amplifiers being connected to the cathodes of the respective first and second diodes and the input terminals of the respective first and second amplifiers being connected to the anodes of the respective second and first diodes, and first and second impedances connecting the respective output terminals of the respective first and second amplifiers to a point of reference potential whereby the first and second signals are generated on the output terminals of the respective first and second amplifiers, the first and second signals being equal when the lamp is operative and unequal when the lamp is inoperative; a detector that is responsive to the first and second signals and is effective to generate a certain control signal when the first and second signals are unequal, the detector including a third controlled amplifier having control and input terminals connected to the output terminals of the respective first and second amplifiers and an output terminal on which is generated the control signal; an indicator device for indicating that the lamp has failed; and an output amplifier that is responsive to the control signal and effective when the certain control signal is generated to cause the indicator device to indicate that the lamp has failed.