Light intensity control device and circuit therefor

Claim 3

A device as in claim 1 and wherein: said switchable resistive network includes a first switch (SA) having a first position (SA2) for enabling charging of said capacitor and a second position (SA1 or 3) for enabling discharge of said capacitor whereby in said first position said light emitting diode increases in light intensity and in said second position said light emitting diode decreases in intensity.

Claim 4

A device as in claim 2 and wherein: said switchable resistive network includes timer switch (ST) means, a second light emitting diode (12) connected to receive electric current upon actuation of said timer switch, a second photoresistor (18) positioned to receive light emitted by said second light emitting diode, means for limiting the current to said second light emitting diode so that said second light emitting diode will flash on and off once upon actuation of said timer switch and momentarily lower the resistance of said second photoresistor and enable the power supplied to said load to turn on at a minimum initial level.

Claim 5

A device as in claim 3 and wherein: said switchable resistive network includes a plurality of selectable resistors for selectively enabling different rates of increase and different rates of decrease in supplied power, and a second switch (SB) for selecting the desired of said resistors.

Claim 6

A device as in claim 4 and wherein: said timer switch means includes a timer switch and a secondary switching device whereby actuation of said timer switch activates said secondary switching device and connects said first and second switches and thereby increases power supplied to said load at a rate determined by a variable resistor (R7).

Claim 7

A device as in claim 2 and wherein: said switchable resistive network includes a variable resistor (R2) for adjusting the minimum voltage supplied to said gate electrode and thereby the minimum power supplied to said load.

Claim 8

A device as in claim 5 or 6 and wherein said first switching device comprises a junction field effect transistor.

Claim 9

A variable power intensity control circuit, comprising: (a) a power input line, (b) a power output line adapted to be connected to an electrical load, (c) electrical conducting means connecting between the power input and power output lines for passing a variable amount of electrical energy from the input to the output line to thereby control the load intensity supplied to the electrical load, (d) a control element connected to the electrical conducting means for regulating the amount of electrical energy passed therethrough dependent upon the electrical state of the control element, and (e) control circuit means connected to the control element and having a plurality of manually selectable settings for supplying a selected variably increasing or decreasing power output dependent upon such settings and present power output so as to vary the electrical state on the control element to provide an instantaneous change ranging from negligible to significant in the power supplied followed by a gradually increased or decreased power supply through the electrical conducting means at a preselected instantaneous change in power and rate of change in power dependent upon such settings to a given preselected power level such that the power supplied to the load varies in accordance therewith.

Claim 10

A variable power intensity control circuit, comprising: (a) a power input line, (b) a power output line adapted to be connected to an electrical load, (c) electrical conducting means connecting between the power input and power output lines for passing a variable amount of electrical energy from the input to the output line to thereby control the load intensity supplied to the electrical load, (d) a control element connected to the electrical conducting means for regulating the amount of electrical energy passed therethrough dependent upon the electrical state of the control element, and (e) control circuit means connected to the control element and having a plurality of manually selectable settings for supplying a selected variably increasing or decreasing power output dependent upon such settings and present power output so as to vary the electrical state on the control element to provide an instantaneous change ranging from negligible to significant in the power supplied followed by a gradually increased or decreased power supply through the electrical conducting means at a preselected instantaneous change in power and rate of change in power dependent upon such settings to a given preselected power level such that the power supplied to the load varies in accordance therewith.

Claim 11

The variable power intensity control circuit as set forth in claim 8, wherein: (a) the electrical conducting means being a first gated solid state switching device having an anode and a cathode, (b) the control element including a second solid state switching device having a gate connected to the output of said first switching diode, (c) variable timing network connected to the anode of said first switching device and comprising a chargeable capacitor (C21) and a switchable resistive network for controlling the rate of change of voltage to the anode of said first switching device, (d) diode means for blocking one half-cycle of current to said variable timing network, (e) means for maintaining a voltage on the gate of said first switching device within a range such that the anode voltage control circuit causes said first switching device to fire as a function of the variable timing network, (e) whereby said second switching device conducts current to said load when said first switching device fires and blocks current flow to said load when said first switching device does not fire.

Claim 12

The variable power intensity control circuit as set forth in claim 9, and wherein said switchable resistive network comprises a plurality of serially connected resistors (R26-32) and a switch member (S20) for selectively connecting at least one of said resistors in parallel with said chargeable capacitor and with timer switch means.

Claim 13

The variable power intensity control circuit as set forth in claim 10, and wherein said plurality of resistors includes a first set of said resistors for controlling the rate of increase of power supplied to said load and for obtaining and maintaining the full power steady state condition, and a second set of resistors for controlling the rate of decrease of power supplied to said load and for obtaining and maintaining the no power steady state condition.

Claim 14

The variable power intensity control circuit as set forth in claim 11, and wherein the variable timing network includes a timer associated with the chargeable capacitor and the switchable resistive network for thereby increasing power supplied to the load at a controlled gradually increasing selective rate.

Claim 15

The variable power intensity control circuit as set forth in claim 12, and wherein said serially connected resistors include a variable resistor (R30) for controlling the final steady state condition of partial power supplied to said load and for controlling the rate of change in power supplied to the said load during the transition from one final steady state condition of partial power to the said load to another such steady state condition.

Claim 16

The variable power intensity control circuit as set forth in claim 13, and wherein said means for maintaining a voltage bias on the gate of said first switching device comprises a parallel connected resistor and second capacitor circuit connected through a blocking diode to the gate of said first switching device, whereby when said first set of resistors of said switchable resistive network is selected, said second capacitor of said circuit discharges more than it charges while the supplied power is increasing and when said second set of resistors of said switchable resistive network is selected, said second capacitor charges more than it discharges while the supplied power is decreased and said second capacitor discharges and charges at substantially equal rates when power is supplied to said load at a constant rate.

Claim 17

The variable power intensity control circuit as set forth in claims 8, 9, 10, 11, 12, 13, or 14 for supplying alternating current to said load and including: (a) a third gated solid state switching device (44') having an anode and a cathode, (b) a forth solid state switching device (42') having a gate connected to the output of said third switching device, (c) a second variable timing network connected through a blocking diode to the anode of said third switching device and comprising a third chargeable capacitor (C41') and a second switchable resistive network for determining the discharging time of the said third capacitor, (d) a resistive network (R41') connected between the power source and the anode of the said third switching device, for determining the charging time of the said third capacitor and in conjunction with said second switchable resistive network determines the maximum fraction of supplied voltage to be across the said third capacitor and on the anode of said third switching device, (e) second diode means for passing said one half-cycle of current to anode and grid circuits of said third switching device and blocking the other half-cycle of current, and (f) means for maintaining a voltage on the gate of said third switching device within a range such that the anode voltage control circuit causes said third switching device to fire as a function of the ratio of the resistance in said charging network of said third capacitor to the resistance of the said discharging circuit for the said third capacitor, whereby said fourth switching device conducts current to said load for the remainder of the half-cycle of supplied power when the said third switching device fires and blocks current to the said load during the portion of each half-cycle of supplied power prior to the firing of the said third switching device.

Claim 18

A device as in claim 15 and wherein said first and third switching devices are programmable unijunction transistors and said second and fourth switching devices are silicon controlled rectifiers.