Solar powered lamp having a circuit for providing positive turn-on at low light levels
AssigneeSiemens Solar Industries, L.P.
InventorFred A. Moore
Life of this patent
Estimating the term…
Abstract
A solar powered lamp having a circuit for providing positive turn-on at low light levels causes a light source thereof to undergo a discrete transition to an "on" condition and prevents unnecessary drain on a battery thereof. The circuit comprises a positive feedback loop which amplifies current flow rapidly to a predetermined level at which the light source is illuminated. In doing so, it causes a plurality of solar powered lamps to illuminate at substantially the same time.
Claims13
A solar powered lamp comprising:
- a photovoltaic cell for receiving sunlight and generating electrical energy;
- an electrical storage device coupled to said photovoltaic cell for receiving and storing electrical energy;
- light sensing means other than said photovoltaic cell for generating a control signal in response to ambient light;
- and
- means for providing positive turn-on at a preselected low light level, said positive turn-on means having a feedback loop which amplifies said control signal to apply said electrical energy to the light source, said positive turn-on means further comprising:
- a first transistor having a collector, base and emitter;
- a second transistor having a collector, base and emitter, said collector of said first transistor electrically connected to said base of said second transistor;
- and
- a third transistor having a base thereof electrically connected to said emitter of said second transistor.
A solar powered lamp comprising:
- a photovoltaic cell for receiving sunlight and generating electrical energy;
- an electrical storage device coupled to said photovoltaic cell for receiving and storing electrical energy;
- light sensing means for generating a control signal in response to ambient light;
- and
- means for providing positive turn-on at a preselected low light level, said positive turn-on means having a feedback loop which amplifies said control signal to apply said electrical energy to the light source;
- said positive turn-on means further comprising:
- a first transistor having a collector, base and emitter;
- a second transistor having a collector, base and emitter, said collector of said first transistor electrically connected to said base of said second transistor;
- and
- a third transistor having a base thereof electrically connected to said emitter of said second transistor;
- and said feedback loop further comprising:
- a first resistive means electrically connected between said base of said first transistor and said collector of said third transistor;
- a second resistive means electrically connected between said collector of said first transistor and said base of said second transistor;
- and
- a third resistive means electrically connected to said collector of said second transistor, said first, second and third transistors and said first, second and third resistive means connected in a Schmitt trigger configuration.
A plurality of solar powered lamps disposed in proximity to one another at a location, each comprising:
- a photovoltaic cell for receiving sunlight and generating electrical energy;
- an electrical storage device coupled to said photovoltaic cell for receiving and storing electrical energy;
- light sensing means other than said photovoltaic cell for generating a control signal in response to ambient light;
- and
- means for providing positive turn-on at a preselected low light level, said positive turn-on means having a feedback loop which amplifies said control signal to apply said electrical energy to the light source and cause said plurality of solar powered lamps to turn on at substantially the same time.
Dependencies are inferred from the claim text.