Circuitry for portable lighting devices and portable rechargeable electronic devices

Abstract

A flashlight with a circuit for reducing the initial surge of current that is sent through the lamp filament when a flashlight is turned on is provided. The circuit reduces the stresses placed on the lamp bulb when it is turned on, thereby extending the life expectancy of the lamp bulb. A flashlight with an electronic switch is also disclosed.

1 . A portable lighting device comprising:
 a main power circuit including a power source, a light source, and an electronic power switch;   a mechanical switch disposed outside of the main power circuit;   a microprocessor for generating a control signal in response to a closing of the mechanical switch; and   a power control circuit electrically coupled to the electronic power switch and adapted to regulate current flow through the electronic power switch in response to the control signal of the microprocessor.   
     
     
         2 . A portable lighting device according to  claim 1 , wherein the power control circuit regulates current flow through the electronic power switch when the portable lighting device is turned on to limit the peak current that flows through the main power circuit prior to the main power circuit reaching a steady state. 
     
     
         3 . A portable lighting device according to  claim 1 , wherein the light source includes a filament. 
     
     
         4 . A portable lighting device according to  claim 1 , wherein the portable lighting device comprises a flashlight. 
     
     
         5 . A portable lighting device according to  claim 1 , wherein the electronic power switch is a transistor. 
     
     
         6 . A portable lighting device according to  claim 5 , wherein the electronic power switch is an n-channel MOSFET. 
     
     
         7 . A portable lighting device comprising:
 a main power circuit including a power source, a light source, and an electronic power switch;   a circuit board;   a power control circuit formed on the circuit board electrically coupled to the electronic power switch;   a microprocessor formed on the circuit board having an output coupled to the power control circuit; and   a mechanical switch for opening and closing an electrical path between the power source and the microprocessor, wherein the microprocessor provides a control signal through the output of the microprocessor to the power control circuit in response to an activation signal received from the mechanical switch, and the power control circuit modifies the control signal and applies the modified control signal to the electronic power switch.   
     
     
         8 . A portable lighting device according to  claim 7 , wherein the power control circuit regulates the electronic power switch when the portable lighting device is turned on to limit the peak current that flows through the main power circuit prior to the main power circuit reaching a steady state. 
     
     
         9 . A portable lighting device according to  claim 8 , wherein the voltage of the control signal substantially varies according to a step function when the portable lighting device is turned on, and the modified control signal has a voltage that increases over time. 
     
     
         10 . A portable lighting device according to  claim 9 , wherein the voltage of the modified control signal has a voltage that increases exponentially over time. 
     
     
         11 . A portable lighting device according to  claim 8 , wherein the electronic power switch is a transistor. 
     
     
         12 . A portable lighting device according to  claim 11 , wherein the electronic power switch is an n-channel MOSFET and the power control circuit applies the modified control signal to the gate of the MOSFET. 
     
     
         13 . A flashlight comprising:
 a main power circuit including a power source, a lamp, and an electronic power switch;   a circuit board; and   a power control circuit formed on the circuit board and adapted to provide a control signal to the electronic power switch while the flashlight is turned on, wherein the amount of current the electronic power switch is capable of conducting in the main power circuit is dependent on the voltage of the control signal applied to the electronic power switch, and wherein the power control circuit is configured to vary the voltage of the control signal in a manner that increases the amount of current that can flow through the power switch over a predetermined period when the flashlight is turned on.   
     
     
         14 . A flashlight according to  claim 13 , wherein the predetermined period is greater than 10 milliseconds. 
     
     
         15 . A flashlight according to  claim 13 , wherein the predetermined period is greater than the time required for the main power circuit to reach a steady state after the flashlight is turned on. 
     
     
         16 . A flashlight according to  claim 13 , wherein the power control circuit varies the voltage of the signal according to an exponential function. 
     
     
         17 . A flashlight according to  claim 16 , wherein the voltage of the signal increases exponentially. 
     
     
         18 . A flashlight according to  claim 13 , wherein the electronic power switch comprises a transistor. 
     
     
         19 . A flashlight according to  claim 18 , wherein the electronic power switch comprises a field effect transistor and the signal is applied to the gate of the transistor. 
     
     
         20 . A flashlight according to  claim 13 , wherein the lamp includes a filament.