Initializing controlled transition light dimmers

An electronic dimming apparatus comprising:

• a semiconductor power controller for selectively coupling a lamp load with an alternating current supply, said alternating current supply supplying alternating current, said alternating current having positive and negative half-cycles, said semiconductor power controller including
• at least one first semiconductor power device having a first control input said at least one first semiconductor power device coupling or uncoupling said lamp load with said alternating current supply during said positive half-cycles responsive to a change in a control value then being applied to said first control input, and
• at least one second semiconductor power device having a second control input said at least one second semiconductor power device coupling or uncoupling said lamp load with said alternating current supply during said negative half-cycles responsive to a change in a control value then being applied to said second control input;
• a control circuit, coupled with said first and said second control inputs, said control circuit having a third input for receiving a value indicative of a desired amount of power to be supplied to said lamp load, the control circuit determining a phase angle of a half-cycle of said alternating current at which a transition between a first one and a subsequent other one of said coupled and uncoupled conditions would supply said desired amount of power to said lamp load, the control circuit changing, at said phase angle, the control value being applied to said control input of said semiconductor power device coupling and uncoupling during said half-cycle between a first one and a subsequent other control values to produce said first one and said subsequent other coupled and uncoupled conditions to increase a duration of said transition to a period greater than a minimum possible said duration and less than a remainder of said half-cycle, such that the electro-magnetic interference product of said transition is reduced,
• said control value applied to said control input being returned to substantially said first control value during a half-cycle subsequent to said half-cycle.

A method of operation for a lamp dimmer, said lamp dimmer having an input, comprising the steps of:

• a) coupling between an alternating current supply and an output suitable for a lamp load, said alternating current supply supplying alternating current, said alternating current having positive and negative half-cycles, at least one semiconductor power device for modulating, responsive to a control value, the instantaneous power supplied to said lamp load during positive half-cycles of said alternating current, and at least one semiconductor power device for modulating, responsive to a control value, the instantaneous power supplied to said lamp load during negative half-cycles of said alternating current;
• b) inputting a first value via said input as indicative of a desired amount of RMS power to be supplied to said lamp load;
• c) determining a phase angle of a half-cycle of said alternating current supply at which a transition between one and the other of substantially conductive and substantially non-conductive power conditions by said at least one semiconductor power device for modulating half-cycles of the polarity of said half-cycle would supply said desired amount of RMS power to said lamp load;
• d) controlling said control value applied to said at least one semiconductor power device so as to effect said transition over a period sufficiently greater than a minimum possible period and less than a remainder of said half-cycle to reduce the electromagnetic interference product of said transition;
• e) initializing said control value applied to said at least one semiconductor power control device after a subsequent reversal of polarity of said alternating current.

A method of operation for a lamp dimmer, said lamp dimmer having an input, comprising the steps of:

• a) coupling between an alternating current supply and an output suitable for a lamp load, a semiconductor power controller for modulating, responsive to a control value, the instantaneous power supplied to said lamp load;
• b) inputting a first value via said input as indicative of a desired amount of RMS power to be supplied to said lamp load;
• c) changing said semiconductor power controller between non-conductive and conductive power conditions at a phase angle during a first half-cycle of said alternating current;
• d) changing said semiconductor power coiltrolling means from said conductive to said non-conductive power condition at a phase angle during a half-cycle subsequent to said first half-cycle;
• e) locating said phase angles in said first and said subsequent half-cycles so as to supply said lamp load with said desired amount of RMS power;
• f) controlling said control value applied to said semiconductor power controller so as to effect said changes over durations sufficiently greater than minimum possible periods and less than remainders of said half-cycles so as to reduce the electromagnetic interference product of said changes.

An electronic dimming apparatus comprising:

• a semiconductor power controller for selectively coupling a lamp load with an alternating current supply, said alternating current supply supplying alternating current, said alternating current having positive and negative half-cycles, said semiconductor power controller including
• at least one first semiconductor power device having a first control input, said at least one first semiconductor power device coupling or uncoupling said lamp load with said alternating current supply during said positive half-cycles responsive to a control value applied to at least said first control input, and
• at least one second semiconductor power device having a second control input, said at least one second semiconductor power device coupling or uncoupling said lamp load with said alternating current supply during said negative half-cycles responsive to a control value applied to at least said second control input;
• a control circuit, coupled with said first and said second control inputs, said control circuit determining at least one phase angle of a half-cycle of said alternating current at which a transition between a first one and a subsequent other one of said coupled and uncoupled conditions would supply a desired amount of power to said lamp load, said control circuit producing control values coupled with said first and said second control inputs, said control values producing said first one and said subsequent other one of said coupled and uncoupled conditions and increasing the duration of said transition to a duration greater than a minimum possible said duration and less than a remainder of said halfcycle, such that the electro-magnetic interference product of said transition is reduced,
• said semiconductor power devices being initialized during half-cycles of a polarity opposite those in which said semiconductor power devices couple and uncouple.