Digital electronic dimmer

Abstract

Disclosed is a lamp-dimmer which employs a novel circuit to provide a digitally selected and phase-shifted trigger-impulse for firing a triac.

What is claimed is: 
     
       1. An electronic circuit for digital phase-shifted triggering of a triac to vary the amount of power to a load from a line voltage source, comprising: (a) signal input means for receiving a plurality of input signals;   (b) discriminator means for generating on/off and power change signals in response to input signals received;   (c) oscillator means for providing a subdividing signal having a frequency higher than the line voltage;   (d) phase shift counter means for generating a plurality of phase shift signals within each half-period of the line voltage in response to the subdividing signal, each of the phase shift signals representing a different potential phase-shifted firing time for the triac within each half period of the line voltage;   (e) power level counter means for selecting and storing one of a plurality of power level signals in response to a power change signal generated by said discriminator means; and   (f) matrix means for evaluating the stored power level signal and the plurality of phase shift signals to determine a firing time for the triac which corresponds to the stored power level signal and for generating a trigger signal for firing the triac at the firing time selected.   
     
     
       2. The electronic circuit according to claim 1, wherein said discriminator means comprises: reset means for resetting said phase shift counter means after the passage of a time interval equal to a half-period of the line voltage.   
     
     
       3. The electronic circuit according to claim 2, wherein said reset means comprises: zero-crossing reset means for resetting said phase shift counter means at half-period intervals which substantially correspond to the zero voltage levels of the line voltage.   
     
     
       4. The electronic circuit according to claim 1, wherein: said discriminator means digitally generates digital power change signals and said phase shift counter means digitally generates digital phase shift signals.   
     
     
       5. The electronic circuit of claim 1, wherein: said discriminator means, said oscillator means, phase shift counter means, and said power level counter means are fabricated in MOS integrated circuit technology.   
     
     
       6. The electronic circuit of claim 1, wherein said signal input means receives a plurality of input signals of varying time durations and said discriminator means further comprises: (a) first control means for switching said electronic circuit on if off and off if on in response to a first input signal of less than a first time duration;   (b) second control means which directs the power level counter means to select another power level signal in response to a second input signal of a second time duration whereby the first and second control means interpret the length of the input signal and thereby determine whether said electronic circuit is turned off, turned on, or turned on and the power to the load varied regardless of previous input signals received by the input signal means.   
     
     
       7. The electronic circuit according to claim 6, wherein said discriminator means further compromises: inhibit means for inhibiting the operation of said first control means in response to an input signal having a time duration longer than that of the first input signal.   
     
     
       8. The electronic circuit according to claim 7, wherein: the second input signal has a longer time duration than the first input signal.   
     
     
       9. The electronic circuit according to claim 7, wherein: the leading edge of the first input signal switches said electronic circuit on if off whereas the trailing edge switches said electronic circuit off if on whenever the first input signal is less than or equal to the first time interval.   
     
     
       10. The electronic circuit according to claim 7, wherein: the electronic circuit varies the power to a lamp in response to a second input signal of a second time duration whereby the illumination level of the lamp is changed.   
     
     
       11. The electronic circuit according to claim 7, wherein the input signal comprises a signal generated by touching a touch plate and said input signal means comprises: touch control means for generating a digital input signal in response to the touch generated signal wherein the time duration of the digital input signal is proportional to the time duration of the touch generated signal.   
     
     
       12. The electronic circuit according to claim 1, wherein said discriminator means comprises: digital filtering means which passes the digital input signals derived from an L-signal but prevents the passage of high-frequency noise-spikes.   
     
     
       13. The electronic circuit according to claim 12, wherein: said digital filtering means also passes digital input signals derived from 50/60 HZ alternating current line voltage.   
     
     
       14. The electronic circuit according to claim 1, further comprising: strobe means for shaping the trigger signal for firing the triac.   
     
     
       15. An electronic circuit for digital phase-shifted triggering of a triac to vary the amount of power to a load from a line voltage source, comprising: (a) signal input means for receiving a plurality of input signals of varying time durations;   (b) discriminator means for interpreting each of said input signals according to the time duration of the input signal, said discriminator means comprising: (1) first control means for switching the electronic circuit on if off or off if on in response to an input signal having a time duration less than a specified time interval; and   (2) second control means for digitally generating a power change signal in response to an input signal having a time duration of greater than the specified time interval;     (c) digital triggering means for digitally determining a phase-shifted firing time within each half-period of the line voltage in response to the power change signal and for generating a triggering signal for firing the triac at the firing time selected.   
     
     
       16. The electronic circuit according to claim 15, wherein the input signal comprises a signal generated by touching a touch plate and said input signal means compromises: touch control means for generating a digital input signal in response to the touch generated signal wherein the time duration of the digital input signal is proportional to the time duration of the touch generated signal.   
     
     
       17. The electronic circuit according to claim 16, wherein said discriminator means further comprises: digital filtering means which passes the touch-generated digital input signals derived from an L-signal but prevents the passage of high frequency noise spikes.   
     
     
       18. The electronic circuit according to claim 17, wherein: said digital filtering means also passes digital input signals derived from 50/60 HZ alternating current line voltage.   
     
     
       19. The electronic circuit according to claim 15, wherein: said discriminator means and said digital triggering means are fabricated in MOS integrated circuit technology.   
     
     
       20. The electronic circuit according to claim 15, wherein: the leading edge of an input signal having a time duration less than the specified time interval switches said electronic circuit on if off whereas the trailing edge of the input signal having a time duration less than a specified time interval switches said electronic circuit off if on.   
     
     
       21. The electronic circuit according to claim 15, wherein: the electronic circuit varies the power to a lamp in response to an input signal having a time duration of greater than the specified time interval whereby the illumination level of the lamp is changed.