Two terminal controller

Abstract

A two-terminal, alternating current power control device connected in an electrical path between a load and a remote switch, comprising a current switching device, a controlling device and a direct current power supply device. The current switching device provides a low impedance electrical path in response to the application of triggering signals thereto, and provides a high impedance electrical path in the absence of the triggering signals. A control circuit is provided for applying triggering signals to the current switching device as the proper time in the ac cycle, and is responsive to a momentary interruption in the applied ac voltage so as to effect change in the power intensity or timed duration of power delivered to the load. A remote switch in the electrical path can be the source of a momentary power interruption. The entire power control device can be constructed to directly attach to the electrical screw shell base of a gas discharge lamp, so the lamp and power control device can be mounted into the normal accommodating electrical fixture without the need for an intermediary fixture or additional electrical wiring.

Description

3A-3B terminals 4 and 5, which are connected in a series with a load 15, a main remote power switch 16, and an AC source 17.

FIG. 1 depicts a controllable conductivity or impedance device or switch such as a triac semi-conductor switch 1 in series with . .triac.!. the power terminals 4 and 5. A triac is a bidirectional dual silicon controlled rectifier (SCR) which can conduct current in both directions only upon the application of a short low voltage current pulse applied to the gate terminal 6 at the proper time in the AC cycle. The triac will then latch into conduction for the remainder of the positive or negative going AC cycle until the impressed voltage across terminals 4 and 5 is at or near zero, at which time the triac returns to its normally high impedance state until again triggered.

Also included within power controller 10 as shown in FIG. 1 is a direct current power supply means 2, which has two terminals 2a and 2b connected in shunt with the triac 1, whereby the voltage across the said triac when it is in normally high impedance state is reduced in magnitude by any number of well-known means, and is rectified and filtered to become a steady source of direct current at a third terminal 2c.

Also comprising power controller 10 as shown in FIG. 1 is a micro-processor control circuit 3, being powered by DC source 2 and having voltage sensing terminal 3a to detect the AC zero crossing across terminals 4 and 5 when said triac 1 is in a nonconduction state. Also, a trigger terminal 3b connected directly to triac gate trigger la triggers said triac into conduction at the proper time in the AC waveform. The micro-processor control circuit can be any combination of generally known computer devices, memories, input/output devices, etc. Such control circuit has a property to retain data recently stored in the memory elements even during relatively long periods of power interruption, such interruption caused by the . .intentionaly.!. intentional opening of the remote switch, or by an unanticipated power failure. In the present embodiment the device is a single chip 4-bit micro-controller being readily commercially available having internal random access memory (RAM), read only memory (ROM), and Input/Output (I/O) drivers. The many possible operating modes of the complete power controller 10 and the controller responses to momentary interruptions in the applied AC voltage are determined by the computer program resident in internal ROM.

As an illustrative example, the power controller 10 of FIG. 1 can be a means of modulating the power intensity delivered to a heating, lighting or motor load. After initially closing remote switch 16, the power to the load will be maintained at some initial value determined by the period of time the triac remains in a high impedance state following a zero crossing, and prior to the micro-processor control circuit issuing a command to fire the triac into a conducting state. By programming the microprocessor control circuit to sense a power interruption caused by the rapid opening and closing of remote switch 16, the power delivered to the load can be varied. By modifying when the triac is triggered into conduction after zero voltage crossing of the applied AC waveform across triac terminals 4 and 5, various preprogrammed values can be selected. . .Successive.!. A pattern of sequence of successive short power interruptions can modify firing of the triac to create an entire range of power intensity values delivered to the load. For example, a single on-off sequence of switch 16 can be programmed to supply full power to load 15; two on-off sequences might produce 60% power, and three such sequences might supply 40% power.

In another embodiment, the apparatus of the present invention can be used as a delay timer, as for household lighting. The power controller 10, when connected to an existing load and remote switch of FIG. 1, can be programmed to turn on or turn off a load after a specific time interval following the closure of remote switch 16. Variable timed interval duration can be selected by a user such that the period of delay can be selected depending upon how many on-off cycles of switch 16 the user initiates.

. .As.!. In yet another embodiment, the power controller 10 can provide be programmed to provide a "soft-start" to a load at initial remote switch 16 closure. By initially delaying the firing of the triac well beyond the zero crossing of the AC waveform impressed across the triac terminal 4 and 5, the initial power surge can be dampened and load life increased. Rather than using phase control as in commercially available solid state dimmer switches designed for use with incandescent lighting circuits, the power controller 10 controls the rate of power increase to full power after initial turn on according to the particular program instructions resident in ROM.

Operation of the power controller 10 of FIG. 1 above can be best understood by referring to FIG. 2, which depicts voltage waveforms A, B, C and D with respect to time. Assuming the AC source of FIG. 1 is 115 volts RMS, 60 hertz, the peak voltage excursions of the sinusoidal waveform approach +/-187 volts with a period of approximately 16.66 milliseconds. Curve A represents the voltage impressed across the load terminals of FIG. 1; curve B represents the voltage across terminals 4 and 5 of controller 10; curve C is the output of the DC power supply means of controller 10, and curve D is the pulse generated by the microprocessor control circuit which is applied to the gate of triac 1 to trigger the triac into conduction.

Following a very long period with switch 16 "open", upon closure of remote switch 16, at time t=0 of FIG. 2, an AC waveform will be impressed across the triac terminals 4 and 5 (curve B) as long as the triac remains in the high impedance, untriggered state. During this first AC cycle, DC power supply 2 will rectify and reduce in magnitude the applied waveform across terminals 2a and 2b so that a filtered, low ripple DC voltage appears at terminal 2c, as illustrated by curve C of FIG. 2. This voltage, present at the micro-processor power terminal, will then enable the micro-processor to begin executing a unique program or programs resident in the read-only-memory (ROM) or in the form of preprogrammed digital logic. Based on the particular function desired, the micro-processor control circuit may then trigger the triac into conduction at certain desired time delays following the sensed zero crossing at terminal 3a. As illustrated for AC cycles 1-7, of curve D, the soft-start feature can be implemented at initial device turn-on whereby in each successive AC cycle, increasing amounts of power are delivered to the load by simply decreasing the amount of delay between the time the zero crossing occurs as shown in curve B and the time the triac is caused to fire.

In order to maintain the DC power supply at some desired voltage level, it is necessary to fire the triac a minimum of a 5-30 electrical degrees after the zero crossing (curve B). This ensures that the power supply 2 can absorb enough electrical charge from the potential across terminals 4 and 5 of the triac to provide adequate stored charge to operate the micro-processor control circuit during the remaining electrical cycle that the triac is in a conducting state and thus has little potential developed across terminals 4 and 5. FIG. . .3.!. 3A illustrates the effect of full wave phase control, whereby it can be seen that with a 20 electrical degree triggering phase angle, the power delivered to the load will be about 99% of that delivered by a full electrical waveform. To achieve other desired power intensities delivered to the load, it is simply necessary to delay the firing angle of the triac by an appropriate number of electrical degrees.

FIG. 4 is a detailed schematic of one preferred embodiment of the present invention. Triac 1 is connected between terminals 4 and 5 of the power controller 10, and serves as the high current power control switch. The DC power supply includes resistors 23 and 27, diode 24, zener diode 25, and capacitors 26 and 28. Resistor 23 limits the current delivered to the zener diode 25, and serves as a voltage divider with zener 25. Diode 24 prevents current leakage from the power supply when terminal 4 is negative with respect to terminal 5. During the time diode 24 is conducting current, current will flow into capacitor 26 until the voltage across this capacitor equals the zener breakover voltage of zener diode 25. The zener is necessary to limit the voltage impressed across the capacitor 26 to prevent capacitor failure. At the breakover voltage, the zener then shunts any additional current to ground until the triac either triggers into a low impedance state or the voltage polarity across triac terminals 4 and 5 reverses. It is during these times when there is no charging potential across the triac that capacitor 26 serves as a charge reservoir to capacitor 28 additionally serves as a first order filter to substantially smooth the ripple and create more of a true direct current than what would normally be available if capacitor 26 were solely used to filter the pulsating DC.

Microprocessor control circuit 3 is a very low power CMOS device which has all necessary memory, input/output, and computing functions on a single silicon chip. Resistor/capacitor pair 32, 33 form the RC oscillator timebase for the control circuit 3, and can be a crystal or other form of periodic oscillation device. Resistor 29 limits the current from the voltage divider shunt path across triac terminals 4 and 5 to the lower level logic input 3a of control circuit 3 to sense the moment the AC zero crossing occurs across the triac terminals 4 and 5. PNP transistor 30 and base resistor 31 amplify a 10 micro-second triac trigger pulse from the control circuit and apply the needed gate drive pulse to the triac gate to cause the triac to switch from a high to a low impedance state. The triac then remains on until the triac current crosses zero, at which time the triac commutes to a high impedance state. At the next positive half-cycle, the DC power supply circuit is allowed to regain lost charge before the triac is again ready for firing.

FIG. 5 illustrates the typical initial current surge of a gas filled incandescent lamp which is not provided with the soft-start feature of the present invention. This initial current surge of 16 to 20 times the steady state current is responsible for a majority of the triac failures in existing lighting control devices, and also is the primary reason for lamp filament failure at initial turn-on. The present invention can be programmed so that at initial power turn-on, the power intensity delivered to the load is modulated for an initial very low power level necessary to prewarm the filament, to gradually increasing power over a number of electrical cycles to near 100% of full power if desired. FIG. 2, (curve B) cycles 1-7 illustrate this feature. Using the soft-start power modulation of the present invention, incandescent bulb life has been increased by a factor of five, while average bulb power as maintained at near 100% after initially soft-starting.

FIG. 6 illustrates a preferred packaging arrangement for the two-terminal power controller as described above when used as an individual incandescent light bulb controller for Edison base style lamps. By employing current manufacturing technologies such as surface mounting of components and chip on board die attach techniques, it is possible to package all the components for the inventive power controller into a thin disc less than three millimeters thick and less than 23 millimeters in diameter. Terminals 4 and 5 of the triac power switching device are positioned centrally on the opposing planar faces of a disc 40, this disc being attached by adhesive foamed tape 41 to the base of the lamp screw shell housing 42. Negligible space between the bulb center contact 44 and the fixture center contact 45 of FIG. 6 is consumed. By mounting the present invention as illustrated in FIG. 6, all existing wiring, switches, and fixtures can remain intact, and no modification of the electrical circuit is required by the installer. The invention is susceptible to use in many different and useful lighting control functions, including, but not limited to: soft-starting the filament power for increased bulb life; lamp dimming to predefined or selected intensity levels by the controller responsive to short power interruptions; and allowing predefined or selected time intervals to elapse after initial power application whereby the lighting load is either turned on or off in a singly or multiply occurring sequence at single or repeated intervals of time.

Thus, there has been described a two-terminal power control device which may greatly expand the usefulness of a great variety of alternating current circuits, especially in the area of lighting control, where new useful functions can be added to existing circuits without the need for wiring modifications, with the added benefit of significantly increasing bulb life.

While a preferred embodiment of the invention has been disclosed, various modes of carrying out the principles disclosed herein are contemplated as being within the scope of the following claims. Therefore, it is understood that the scope of the invention is not to be limited except as otherwise set forth in the claims.

Claims

1. A two-terminal power control device normally in an off condition until activated by switch means to conduct power from an ac power source to a power load, said device comprising:

a. input and output terminals . .adjacent an.!. adapted to be connected to the ac power source and . .a.!. the power load, respectively;

b. . .A.!. a bi-directional dual silicon controlled rectifier responsive to low voltage current pulses, said rectifier in series with and between the input and output terminals;

c. micro-processor control circuit means in series with and providing triggering signals to the rectifier, and responsive to momentary power interruptions in the form of operator-controlled . .activation.!. activations of the switch means;

d. DC power supply means connected across the rectifier to provide power to the control circuit means when the rectifier is in a state of high or low impedance . .and.!. in . .absence.!. the presence of ac potential across the rectifier;

e. memory data retention means coupled to control circuit means to retain . .recently.!. stored data during periods of power removal from said ac power source,

f. the input and output terminals on opposed upper and lower surfaces of a package, said package having dimensions . .such that it is.!. to allow it to be retained between an Edison-style lamp screw shell housing and an incandescent bulb inserted therein, and

g. said power control device being provided with a timer responsive to momentary power interruptions.

2. The device as recited in claim 1, wherein the load comprises an incandescent bulb activated by the switch means.

3. The device as recited in claim 1, wherein the microprocessor control circuit means delays the activation of the rectifier until after a zero crossing of an ac waveform impressed across the input and output terminals.

4. The device as recited in claim 1, wherein the microprocessor control circuit means is programmed to provide a predetermined level of power to the load depending upon the number of on-off . .cycles.!. activations of the switch means.

5. A method of providing power from an ac power source to an electrical load . .responsive.!. in response to momentary power interruptions resulting from activations of switch means connected to the ac power source, comprising the steps of:

a. programming a micro-processor . .controlled.!. control circuit means to be responsive to momentary power interruptions initiated by an operator and applied to the micro-processor control circuit means at an input terminal and an output terminal to which the microprocessor control circuit means is connected;

a. connecting a bi-directional dual silicon controlled rectifier in series with and between . .a pair of.!. input and output terminals and interconnecting the input and output terminals in series with . .an.!. the ac power source and the electrical load and connecting the micro-processor control circuit means for controlling the conduction of the rectifier;

c. interrupting the ac power . .supply.!. source to the microprocessor control circuit means such that responsive thereto the micro-processor . .provides.!. control circuit means controls the delivery of power to the . .a.!. the load in a predetermined manner,

d. packaging said micro-processor control circuit means, said rectifier and said input and output terminals in a . .and.!. adapted for inserting said package between an Edison-style lamp screw shell housing and an incandescent bulb inserted therein, and

e. providing a timer in said package connected to the micro-processor control circuit means which is responsive to momentary power interruptions.

6. The method as recited in claim 5, further comprising interrupting the ac power source . .supply.!. source in order to cause the micro-processor control circuit means to control the rectifier to provide a predetermined level of power to the load depending upon the number of on-off activations . .cycles.!. activations of the switch means.

7. The method as recited in claim 5, further comprising interrupting the ac power . .supply.!. source in order to cause the micro-processor control circuit means to control the rectifier to provide power to the load a predetermined period of time after said last interruption.

8. A method for controlling one of either the conduction time, duty cycle or . .of.!. or illumination intensity of a lamp which comprises the steps of:

a. providing in memory certain data values corresponding to the timing or sequence at which power interruptions to said memory may occur,

b. creating timed or sequenced power interruptions to said memory and thereby

c. selecting a particular data value for storage in said memory which is operable to control either said conduction time, said duty cycle or said illumination intensity of said lamp, and

d. controlling said conduction time, duty cycle, or illumination intensity of said lamp by connecting an ac triggerable switch to said lamp and controlling its conductive state by the application thereto of a signal corresponding to said particular data value selected for storage in said memory.

9. Circuitry for controlling the current level, duty cycle and conduction time for current supplied to a selected load including, in combination:

a. an ac controlled switch connected to a load,

b. data storage and conversion means connected to a gate or control electrode of said ac controlled switch and responsive to manually controlled power interruptions which are made at a predetermined time and sequence with respect to the present current level, duty cycle or current conduction time at said load for in turn changing said current level, duty cycle or conduction time to another and different current level, duty cycle or conduction time, and

c. said ac controlled switch is a Triac which is connectable between one side of said load and one side of an ac supply voltage, said ac supply voltage being further connected through a manually operated and controlled switch to another side of said load, and said data storage and conversion means including a micro-processor connected to a DC voltage supply and further connected across input and output terminals of said Triac and to a gate or control electrode thereof, said micro-processor being operative to store new data values therein in response to the manual switching action of said manually operated switch in a controlled sequence to thereby change the phase angle and conduction time of said semiconductor Triac and thereby in turn control and change the level of current, the duty cycle, or the conduction time of current conducted through said load. 10. A method as defined in claim 8 further comprising steps of:

correlating the durations and seguences of the power interruptions with preprogrammed information within the memory to select said data value, and

using the selected data value to modify the conductive state of the switch to control the conduction time, duty cycle, or illumination intensity of said lamp. 11. A method as defined in claim 10 further comprising the steps of:

g. supplying a termination control signal to terminate the conduction of power through the switch in response one power interruption of a predetermined maximum duration, and

h. supplying a conduction control signal to initiate the conduction of power through the switch in response an application of power across the switch and the connected lamp after a power interruption of greater than

the predetermined maximum duration. 12. A method as defined in claim 11 further comprising the steps of:

i. modifying the conduction control signal to modify the conductive state of the switch in response to a predetermined number of relatively shorter power interruptions which correlate to a data value corresponding to a modified conduction control signal, and

j. restricting each of the relatively shorter power interruptions to a predetermined duration less than the predetermined maximum duration and greater than any power interruption occurring during a zero crossing of an ac power wave form applied across the connection of said switch and said lamp. 13. A method as defined in claim 12 further comprising the step of:

k. modifying the conduction control signal in response to a sequence of a plurality of relatively shorter power interruptions which defines a pattern. 14. A method as defined in claim 13 further comprising the step of:

l. supplying a plurality of different conduction control signals in

response to a plurality of of different patterns. 15. A method as defined in claim 12 further comprising the step of:

k. maintaining the preprogrammed information in the memory during power interruptions at least as long as the predetermined maximum duration. 16. A method as defined in claim 15 further comprising the step of:

l. energizing the memory with power derived from an ac power source from which said switch conducts power to said lamp. 17. A two-terminal power control device normally activated by switch means to conduct power from an ac power source to a load, comprising:

input and output terminals adapted to be connected to the ac power source and the load, respectively;

a controllable conductivity device responsive to control signals and connected in series with and between the input and output terminals, the controllable conductivity device varying the impedance thereof and the conduction of power therethrough in response to the control signals;

a controller connected in series with and operative for supplying control signals to the switch in response to momentary power interruptions resulting from activations of the switch means;

a DC power supply connected across the conductivity device to provide power to the controller when the conductivity device is in a state of high or low impedance in the presence of ac potential across the switch;

a logic circuit memory of the controller to retain preprogrammed data during periods of power termination from the ac power source and the DC power supply,

a package having the input and output terminals connected thereto on opposed ends of the package, the package having dimensions to allow it to be retained between an Edison-style lamp screw shell housing and an incandescent bulb inserted therein, and

a timer of the controller responsive to momentary power interruptions,

the controller correlating the momentary power interruptions to the

preprogrammed data to derive the control signals. 18. A device as defined in claim 17, wherein the load comprises an incandescent bulb energized from the ac power source by conduction of the controllable conductivity device. 19. A device as defined in claim 17, wherein the controller delays the application of the control signal to initiate conduction of the conductivity device until a predetermined time after a zero crossing of an ac waveform impressed across the input and

output terminals. 20. A device as defined in claim 17, wherein the controller supplies different control signals to achieve different levels of conductivity of the controllable conductivity device to apply corresponding different predetermined levels of power to the load depending upon the number of activations of the switch means which create the power interruptions. 21. A method of controllably delivering power from an ac power source to an electrical load in response to momentary power interruptions resulting from activations of switch means connected to the ac power source, comprising the steps of:

connecting a controllable conductivity device in series with and between an input terminal and an output terminal;

interconnecting the input and output terminals in series with the ac power source and the load;

controlling conduction of the controllable conductivity device to control the power applied from the ac power source to the load;

connecting a controller between the input and output terminals;

preprogramming instructions in a data retention element. of the controller to recognize and respond to predetermined momentary power interruptions at the input and output terminals;

connecting to the controller a timer which is responsive to the predetermined momentary power interruptions;

activating the switch means to create predetermined power interruptions at the input and output terminals;

correlating the predetermined power interruptions created by activating the switch means with the preprogrammed instructions;

controlling the conduction of the controllable conductivity device in a predetermined manner related to the correlation between the predetermined momentary power interruptions and the preprogrammed instructions to control the delivery of power to the load in a predetermined manner; and

packaging the controllable conductivity device, the controller including the data retention element and the timer, and the input and output

terminals in a package. 22. A method as defined in claim 21, further comprising the step of:

sizing the package for insertion between an Edison-style lamp screw shell housing and an incandescent bulb inserted therein. 23. A method as defined in claim 21, further comprising the step of:

interrupting the ac power source by a predetermined number of on-off activations of the switch means to cause the controller to control the conductivity device to conduct a predetermined level of power to the load depending upon the number of on-off activations of the switch means.

24. A method as defined in claim 21, further comprising the step of:

interrupting the ac power source by a predetermined characteristic of on-off activations of the switch means to cause the controller to control the conductivity device to conduct power to the load a predetermined period of time after the last interruption. 25. A method for controlling either the conduction time, duty cycle or illumination intensity of a load, comprising the steps of:

selectively creating a plurality of different predetermined timed or sequenced power interruptions which relate to controlling one of either the conduction time, duty cycle or illumination intensity of a load;

preprogramming in a data retention logic element a plurality of predetermined data values each of which relates to a different one of the predetermined power interruptions;

applying the predetermined power interruptions to the data retention element;

comparing the predetermined power interruptions applied to the data retention element with the data values programmed in the data retention element;

selecting from the comparison a particular data value to control said load; and

controlling said load by connecting a controllable conductivity device to said load and by controlling a conductive state of the conductivity device by applying to the conductivity device a control signal corresponding to

the particular data value selected. 26. A method as defined in claim 25 further comprising the steps of:

correlating the durations and sequences of the power interruptions with preprogrammed data values within the data retention logic element to select the particular data value; and

modifying the conductive state of the conductivity device by selecting a new particular data value after a previous particular data value has been selected. 27. A method for controlling one of either the conduction time, duty cycle or illumination intensity of a load, comprising the steps of:

preprogramming in a data retention logic element certain data values corresponding to the timing or sequence at which power interruptions to the data retention element may occur;

creating predetermined timed or sequenced power interruptions to the data retention element;

correlating the predetermined power interruptions created with the data values and thereby

selecting a particular data value to control one of either said conduction time, said duty cycle or said illumination intensity of said load;

controlling the one of said conduction time, duty cycle, or illumination intensity of said load by connecting a controllable conductivity device to said load and by controlling a conductive state of the conductivity device by applying to the conductivity device a control signal corresponding to the particular data value selected; p1 terminating the conductive state of the conductivity device in response to one power interruption of a predetermined maximum duration; and

initiating the conductive state of the conductivity device in response an application of power across the conductivity device and the connected load after a power interruption of greater than the predetermined maximum

duration. 28. A method as defined in claim 27 further comprising the steps of:

modifying the conductive state of the conductivity device in response to a predetermined sequence of relatively shorter power interruptions which define a pattern; and

restricting each of the relatively shorter power interruption to a predetermined duration less than the predetermined maximum duration and greater than any power interruption occurring during a zero crossing of an ac power wave form applied across the input and output terminals.

29. A method as defined in claim 28 further comprising the step of:

modifying the conductive state of the conductivity device in response to a different pattern of relatively shorter power interruptions after the creation of a previous pattern. 30. A method as defined in claim 29 further comprising the step of:

changing the conductive state of the conductivity device in response to each of a plurality of different patterns of relatively shorter power interruptions. 31. A method as defined in claim 28 further comprising the step of:

maintaining the preprogrammed data values in the data retention element during power interruptions at least as long as the predetermined maximum duration. 32. A method as defined in claim 31 further comprising the step of:

energizing the data retention element with power derived from an ac power source from which the conductivity device conducts power to said load.

33. Circuitry for controlling the current level, duty cycle and conduction time of current supplied from a power source to a load comprising, in combination:

a controllable conductivity device adapted to connected in a series combination of the load, the power source, and a power switch to conduct current from the power source to the load when the power switch is closed and the controllable conductivity device is conductive, the controllable conductivity device having a control terminal upon which to apply a control signal for controlling the conductivity of the controllable conductivity device; and

a controller connected to the controllable conductivity device and responsive to a predetermined pattern of power interruptions of predetermined time and sequence created by manual activations of the power switch, the controller supplying a control signal to the control terminal for controlling the conductivity of the controllable conductivity device to establish the current level, duty cycle or conduction time in relation to the predetermined pattern of power interruptions;

the controller including a data storage logic element, a processing logic element, and a DC power supply to which the data storage and processing logic elements are connected, the processing element connected to the control terminal of the controllable conductivity device, the data storage element operatively retaining data values therein and storing information therein in response to the manual activations of the power switch which create the pattern of power interruptions, the processing element operatively supplying a control signal to the control terminal of the controllable conductivity device to thereby change the conductivity of the controllable conductivity device to control and change the level of current, the duty cycle, or the conduction time of current conducted through the load, the processing element deriving the control signal by correlating the predetermined pattern of power interruptions with the data values stored in the data retention element. 34. A power control device for selectively controlling the application of electrical power to a load from an ac power source in response to power interruptions of predetermined durations from the power source, comprising:

two power terminals to connect said power control device in series with the ac power source and at which power interruptions occur;

a controllable conductivity device connected between the two power terminals to selectively conduct power from the ac power source between the two terminals during the application of power from the ac power source, the controllable conductivity device including a control terminal to which to apply a control signal, the control signal varying the conduction of the controllable conductivity device in relation to the control signal and the electrical power from the ac power source; and

a controller connected to the two power terminals and to the control terminal of the controllable conductivity device, the controller including logic elements which are operative to recognize a predetermined pattern of power interruptions of predetermined durations and sequences from the ac power source and to correlate the recognized pattern of power interruptions with preprogrammed information of the logic elements, the controller employing the correlated preprogrammed information to supply control signals to the control terminal of the controllable conductivity device;

the controller supplying a termination control signal to terminate the conduction of power through the controllable conductivity device in response a power interruption of a predetermined maximum duration;

the controller supplying a conduction control signal to initiate the conduction of power through the controllable conductivity device between the power terminals in response an application of power to the power terminals after a power interruption of greater than the predetermined maximum duration; and

the controller modifying the conduction control signal to modify the amount of power conducted through the controllable conductivity device in response a predetermined pattern of a number of relatively shorter power interruptions, each relatively shorter power interruption having a predetermined duration less than the predetermined maximum duration and greater than any power interruption resulting from the zero crossing the

ac power source. 35. A power control device as defined in claim 34 wherein:

the predetermined pattern of the predetermined number of relatively shorter power interruptions to which the controller responds to modify the conduction control signal is a plurality of relatively shorter power interruptions. 36. A power control device as defined in claim 35 wherein:

the predetermined pattern of the plurality of relatively shorter power interruptions modify the conduction control signal to selectively vary the intensity of power supplied by the controllable conductivity device to the load. 37. A power control device as defined in claim 35 wherein:

the predetermined pattern of the plurality of relatively shorter power interruptions modify the conduction control signal to selectively vary the time during which the conduction control signal is applied to the controllable conductivity device to vary the application of power to the load in a corresponding manner. 38. A power control device as defined in claim 35 wherein:

he predetermined pattern of the plurality of relatively shorter power interruptions modify the conduction control signal to selectively vary the time at which the conduction control signal is applied to the controllable conductivity device to apply power to the load in a corresponding manner. 39. A power control device as defined in claim 35 wherein:

the predetermined pattern of the plurality of relatively shorter power interruptions modify the conduction control signal to selectively vary the intensity of power supplied by the controllable conductivity device to the load and the time during which the conduction control signal is applied to the controllable conductivity device. 40. A power control device as defined in claim 35 wherein:

the logic elements of the controller are further operative to recognize the predetermined pattern of the plurality of relatively shorter power interruptions after a power interruption of greater than the predetermined maximum duration. 41. A power control device as defined in claim 40 wherein:

the logic elements of the controller are further operative to recognize a plurality of different predetermined patterns of the relatively shorter power interruptions and are further operative to modify the conduction signal in a different manner in relation to each different pattern. 42. A power control device as defined in claim 41 wherein:

the logic elements of the controller are digital logic elements. 43. A power control device as defined in claim 34 wherein:

the logic elements of the controller are further operative to recognize zero crossings of the ac power at the power terminals and are operative in response to the zero crossings recognized to modify the conduction control

signal in response and relative to a zero crossing. 44. A power control device as defined in claim 34 wherein:

the controller further comprises a DC power supply connected to the power terminals and operative to derive DC power from the ac power present between the terminals;

the controller further operative to modify the conduction control signal to develop a potential between the power terminals for use by the DC power supply. 45. A power control device as defined in claim 44 wherein:

the logic elements of the controller are energized by DC power supplied from the DC power supply; and

the DC power supply further includes a DC power storage element for retaining DC power during the relatively shorter power interruptions and during zero crossings of the ac wave form at the power terminals. 46. A power control device as defined in claim 45 wherein:

the logic elements of the controller are further operative to recognize zero crossings of the ac power at the power terminals and are operative in response to the zero crossings recognized to modify the conduction control

signal in response and relative to a zero crossing. 47. A power control device as defined in claim 46 wherein:

the controller and the power switch are formed on a single integrated circuit. 48. A power control device as defined in claim 47 wherein:

the single integrated circuit and the power terminals are combined in a package in which the power terminals are on opposite ends of the package. 49. A power control device as defined in claim 48 wherein:

the package is of a size to be received between the screw housing of an incandescent bulb and a receptacle into which the screw housing is inserted. 50. A power control device as defined in claim 47 wherein:

the controller comprises digital circuit elements. 51. A power control device as defined in claim 50 wherein:

the controller comprises one of a micro-processor or a micro-controller. 52. A power control device as defined in claim 47 wherein:

the load is a lighting device. 53. A power control device as defined in claim 52 wherein:

the lighting device is one of a gas filled discharge bulb or a incandescent bulb. 54. A power control device as defined in claim 47 wherein:

the load is one of a heating load or a motor load. 55. A power control device as defined in claim 34 wherein:

the controllable conductivity device is a controllable switch.