Abstract:
This invention is an electronic lamp control circuit for connection between a lamp bulb and a wall receptacle controlled by a wall switch. The lamp control circuit includes switching circuitry which permits complete control of the lamp from either the wall switch or a switch included in the lamp control circuit. The lamp control circuit permits a user to turn off the lamp by actuating the wall switch and to later turn on the lamp by actuating the lamp control switch and to turn off the lamp with the lamp control switch and later turn on the lamp using only the wall switch.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to electrical circuits for controlling lamps and more particularly to a circuit for resetting the switch of a lamp so that the lamp may be turned on by actuating a remote electrical power switch after the lamp has been turned off at the lamp switch. 
     In most new housing construction certain rooms, such as bedrooms, ordinarily have no overhead electrical lighting. Electrical lighting in such rooms is obtained by installing a lamp connected to a standard wall plug to supply electrical power to the lamp. A manually activated wall switch controls the flow of electrical power to the wall plug so that the switch must be in the on position in order to turn on the lamp. The lamp ordinarily includes a lamp switch that must also be in the on position for the electric light bulb in the lamp receives electrical power. A person going to bed at night might turn off the lamp by moving the lamp switch to the off position, leaving the wall switch in the on position. If the lamp switch is not subsequently moved to the on position, then a person entering the room will be unable to turn on the lamp by actuating the wall switch. It is therefore necessary to walk into the room, which may be darkened, in order to gain access to the lamp switch to turn on the lamp. Entering a darkened room is inconvenient and may be dangerous. 
     SUMMARY OF THE INVENTION 
     This invention provides a small, self-contained electronic lamp control circuit for connection between a lamp bulb and a wall receptacle that is controlled by a wall switch. The invention provides for complete control of the lamp from either the wall switch or the lamp control circuit. The invention also may include a dimming control that may be actuated from either the wall switch or the lamp control circuit. 
     The lamp control circuit according to the invention may be packaged as a screw-in module that is placed between the bulb and the existing socket of a lamp fixture. The lamp control circuit may also be packaged as a module for connection in-line with the lamp cord that connects the lamp to the wall socket. 
     The lamp control circuit provides means by which a user may turn off the lamp by actuating the wall switch and may later turn on the lamp by actuating the module switch. The user may turn off the lamp with the module switch and later turn on the lamp using only the wall switch. 
     The invention also may include a dimmer control circuit that provides control of the lamp current and, consequently, the brightness of the lamp bulb. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram illustrating installation locations for a lamp control circuit according to the invention in a circuit for supplying electrical power to an electric lightbulb; 
     FIGS. 2a and 2b illustrate possible configurations of the lamp control circuit module for screw-in installation in a lamp socket and for installation in-line between a lamp switch and an electric wall receptacle; 
     FIG. 3 is an on/off operating state diagram of the lamp control circuit of the invention without a dimmer control; 
     FIG. 4 is an on/off operating state diagram of a lamp control circuit according to the invention including a dimmer control; and 
     FIG. 5 is a block diagram of a lamp control circuit according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a lamp bulb 10 connected through a lamp switch 16 to a wall receptacle 12 that is controlled by a wall switch 14. A lamp control module 18 shown in phantom lines may be connected between the lamp 10 and the lamp switch 16 or between the lamp switch 16 and the wall receptacle 12. 
     Referring to FIG. 2a, an exemplary preferred embodiment of the lamp control module 18 has a male threaded end 22 configured for threaded engagement in an ordinary Edison lamp socket (not shown) and a female threaded end 24 for receiving the lamp bulb 10 therein. The lamp control module 18 includes a touch switch 26 for controlling the flow of electrical current to the lamp bulb 10. 
     FIG. 2b illustrates the second preferred embodiment of a lamp control module 18a for connection in line between the wall receptacle 12 and the lamp switch 16. The control module 18a has a pair of electrical terminals 40 and 42 for connection to the wires 36 and 38. The control module 18a includes a touch control switch 26a similar to the touch control switch 26 of the control module 18. 
     FIG. 1 illustrates connection of the wall switch 14, the wall receptacle 12, the lamp 10 and the control module 18 to a source of electrical power (not shown). For simplicity the wall switch 14 is shown to be single-pole, single-throw switch; but the wall switch 14 may also be a double-pole single-throw switch or any other suitable switch. In the illustrated embodiment, the wall switch 14 has a first pole 28 connected to the power source and a second pole 30 connected to terminal 32 of the wall receptacle 12. A second pole 34 of the wall receptacle 12 is connected directly to the power source. A wire 36 extend between the wall receptacle 12 and the lamp switch 16, which is also conveniently shown to be a single-pole single-throw switch; and a wire 38 extends between the wall receptacle 12 and the control module 18 when the control module 18 is mounted between the lamp bulb 10 and the lamp switch 16. 
     Referring to FIG. 5, the control module 18 is shown connected between the lamp bulb 10 and the lamp switch 16, which is normally in the on position. The control module 18 includes a power supply 44 that is connected between the wires 38 and the lamp switch 16, which are connected to the wall receptacle 12. The power supply 44 provides electrical power to a power on-reset switch 46 for application to a flip-flop 48. The flip-flop 48 also receives an input from the touch control switch 26. The output of the flip-flop 48 is supplied to a zero crossing detector 50 having an output connected to a triac 52 which is connected to the lamp bulb 10. The power supply 44 provides a temporary power capability by utilizing conventional means such as a charged capacitor (not shown) to supply electrical power to the flip-flop after the wall switch 14 has been actuated to interrupt the flow of electrical power to the lamp bulb 10. Maintaining a supply of electrical power to the power on-reset 46 and the flip-flop 48 causes these components to remain active in controlling the future conductive state of the triac 52 according to inputs from the wall switch 14 or the touch control 26. The power supply 44 should supply sufficient power to maintain the power on-reset 44 and the flip-flop 48 active for a period of 2-4 seconds. 
     When the user desires to turn off the lamp bulb 10 using the wall switch 14, the wall switch 14 is flashed, or turned off momentarily and then turned on again. The duration of the flash should be approximately one-half to one second in order to the give the flip-flop 48 adequate time to change output states. 
     Ordinarily, the wall switch 14 is in the on position to leave the wall receptacle 12 energized because unless the wall receptacle 12 is energized, no electrical power will flow therefrom to the lamp bulb 10. Flashing the wall switch 14 causes an intermittent interruption in power to the wall receptacle 12 and to the lamp control module 18 connected thereto. Flashing the wall switch 14 toggles the state of the flip-flop 48 to control application of energy to the lamp bulb 10. If the lamp bulb 10 is de-energized, or off, prior to a flash, then after the flash, the lamp bulb 10 is energized. Similarly, if the lamp bulb 10 is energized prior to a flash, the flash will toggle the flip-flop 48 to de-energize the lamp bulb 10 after the flash. 
     The user merely touches a touch plate 56 of the touch control 26 to cause the touch control 26 to output a signal that toggles the flip-flop 48. 
     The lamp control module 18 may include a dimming control circuit 54 connected between the zero crossing detector 50 and the triac 52. The output of the dimming control circuit 54 is a ramp signal which controls the output of the triac 52 to the lamp bulb 10. Operation of the dimming control 54 is similar to that of the on/off operation described above except that two flashes are required to control the dimming. The first flash starts the dimming control circuit, which ramps, or slowly adjusts, current to the lamp bulb 10. The second flash latches the dimmer control circuit 54 to maintain the lamp current at a constant effective value, thereby maintaining a constant light intensity output from the lamp bulb 10. 
     Periods in which the wall switch 14 is off are represented as pulses in FIGS. 3 and 4. Referring to FIG. 4, the wall switch 14 is normally on and a plurality of negative pulses 57-61 indicate periods during which the wall switch 14 is turned off for brief periods. Ordinarily the control module 18 is not touched while the wall switch 14 is being actuated. If the current to the lamp bulb 10 is at a maximum value with the wall switch 14 on, then flashing the wall switch 14 to produce the pulse 57 causes the effective value of the current to decrease until the second flash of the wall switch 14 produces the pulse 58, which then clamps the lamp current at a steady value until the wall switch 14 is flashed again to produce the pulse 59. The pulse 59 causes the lamp current to decrease at a uniform rate until the current amplitude becomes zero, indicating that the lamp bulb 10 is completely de-energized. The lamp bulb 10 remains de-energized until the wall switch 14 is flashed again to produce the pulse 60 which causes the lamp current to increase from its preceding value until the wall switch 14 is again flashed to produce the pulse 61, which causes the lamp current to remain fixed. 
     It is possible to actuate the dimming control 54 through the lamp control module 18. Touching the touch plate 56 of the control circuit 26 forms a pulse 62 which toggles the flip-flop 48, causing the lamp current to increase to its maximum value. The current remains constant until the touch plate 56 is again touched to produce a pulse 63 which causes the current to decrease, thereby dimming the lamp bulb 10. Touching the touch plate 56 a third time produces a pulse 64 which clamps the lamp current at a fixed level until subsequent actuation of either the wall switch 14 or the touch control circuit 26. 
     FIG. 3 is an operating state diagram for the circuit which does not include the dimming control 54. If the lamp control module 18 does not include the dimmer control 54, then the output of the zero-crossing detector controls whether the triac 52 is on to supply current to the lamp bulb 10 or off to interrupt current flow to the lamp bulb 10. The wall switch 14 and the lamp switch 16 are normally in the on positions, and flashing the wall switch 14 produces a pulse 66 that causes the lamp current to decrease from its maximum value to zero. The current remains at zero until a second flashing of the wall switch 14 produces a pulse 67 to toggle the flip-flop 48 to switch the triac 52 to a conducting state. When the wall switch 14 remains in the off position, the system is not operable and the lamp current is zero. Touching the touch plate 56 to produce a pulse 68 when the wall switch 14 is off fails to energize the lamp bulb 10 because no current reaches the lamp bulb 10 when the wall switch remains in the off position. Similarly, the lamp switch 16 must always be in the on position. When the wall switch 14 is placed in the on position again, the lamp current switches from zero to the maximum value until the touch control 56 is actuated to produce a pulse 69 that toggles the flip-flop 48 to switch the triac 52 to a nonconductive state. Subsequent actuation of the touch control produces a pulse 70 that toggles the flip-flop 48 to produce an output that switches the triac 52 to a conductive state so that the lamp current again switches from zero to its maximum value.