Patent US3793557A successfully refreshed from Google Patents.
US3793557A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dimmer circuit and gapped core inductor useful therewith
Assignee: BERKEY COLORTRAN
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Filing: 1972-07-17
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Granted: 1974-02-19
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Expires: 1992-07-17
Abstract
Abstract In a dimmer circuit a summing amplifier combines a light intensity control voltage with a feedback voltage derived from the thyristor controlled ac power supplied to the lamp load. The summing amplifier output establishes the steepness of a ramp signal produced each ac half cycle by a ramp generator. A trigger circuit fires the thyristor device when the ramp signal reaches a certain level. In the feedback circuit a signal transformer coupled from the load is rectified, shaped by filter networks at the rectifier input and output, and used to charge a capacitor via an isolation amplifier. This capacitor provides a feedback voltage which, when summed with the control voltage, achieves a desired functional relationship between control voltage and light intensity, with compensation for load variation. A gapped core inductor is series connected with the ac supply to minimize certain adverse effects associated with turn-on of the thyristor device. Thus, use of the inductor reduces lamp filament vibration and minimizes inductive coupling to adjacent audio and other low level circuits. The inductor core includes both small and large air gaps to provide maximum inductance over a wide range of load current.
Inventors
- 👤 M Cramer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:44
CPC Classifications
H; H01; H01F; H01F38/00; H01F38/02; H01F38/023; G; G05; G05F; G05F1/00; G05F1/10; G05F1/12; G05F1/40; G05F1/44; G05F1/445; H05; H05B; H05B39/00; H05B39/04; H05B39/08; H05B39/083; H05B47/00; H05B47/10; Y; Y10; Y10S; Y10S315/00; Y10S315/07
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
243 words
In a dimmer circuit of the type wherein the light intensity from a lamp is adjusted by controlling the firing angle of one or more thyristor devices supplying ac power to a load comprising said lamp, a circuit for controlling the firing angle of said elements in response to a light intensity control voltage linearly related to the position of an operator actuated dimmer control handle, comprising: a feedback circuit for providing a feedback voltage indicative of the power supplied to said load by said thyristor device, said feedback circuit comprising; means providing a feedback input signal derived from the power supplied to said load by said thyristor device, bridge rectifier means for rectifying said derived feedback input signal, a first resistor-capacitor network across the input of said bridge rectifier means, a second resistor-capacitor network across the output of said bridge rectifier means, said first and second networks providing load variation compensation, an isolation amplifier, a capacitor, and means for charging said capacitor via said isolation amplifier to a level established by the output of said bridge rectifier means, the voltage across said capacitor comprising said feedback voltage, a summing amplifier for combining said control voltage and said feedback voltage to provide an output indicative of the sum thereof, ramp generator means for producing a ramp voltage having a ramp angle established by said summing amplifier output, and trigger means for firing said thyristor device when said ramp voltage exceeds a certain value.
Claim 2
Dependent Claim
243 words
In a dimmer circuit of the type wherein the light intensity from a lamp is adjusted by controlling the firing angle of one or more thyristor devices supplying ac power to a load comprising said lamp, a circuit for controlling the firing angle of said elements in response to a light intensity control voltage linearly related to the position of an operator actuated dimmer control handle, comprising: a feedback circuit for providing a feedback voltage indicative of the power supplied to said load by said thyristor device, said feedback circuit comprising; means providing a feedback input signal derived from the power supplied to said load by said thyristor device, bridge rectifier means for rectifying said derived feedback input signal, a first resistor-capacitor network across the input of said bridge rectifier means, a second resistor-capacitor network across the output of said bridge rectifier means, said first and second networks providing load variation compensation, an isolation amplifier, a capacitor, and means for charging said capacitor via said isolation amplifier to a level established by the output of said bridge rectifier means, the voltage across said capacitor comprising said feedback voltage, a summing amplifier for combining said control voltage and said feedback voltage to provide an output indicative of the sum thereof, ramp generator means for producing a ramp voltage having a ramp angle established by said summing amplifier output, and trigger means for firing said thyristor device when said ramp voltage exceeds a certain value.
Claim 3
Dependent Claim
28 words
A circuit according to claim 1 wherein the component values of said networks are selected to provide linear relationship between control voltage and RMS voltage to said lamp.
Claim 4
Dependent Claim
58 words
A circuit according to claim 1 further including a gapped core inductor in series with the Supply to said load, said inductor having a magnetic flux path including at least two air gaps of different size, said inductor reducing radiative interference associated with thyristor device turn-on, said networks also compensating for control function variation introduced by said inductor.
Claim 5
Dependent Claim
34 words
A circuit according to claim 1 together with means for discharging said capacitor over several cycles of said ac power when said feedback input signal decreases in response to reduction of said control voltage.
Claim 6
Dependent Claim
54 words
A circuit according to claim 1 wherein said ramp generator means comprises: a ramp capacitor, means for discharging said capacitor at the beginning of each half cycle of said source ac, and transistor means for providing charging current to said ramp capacitor, the amount of said current being established by said summing amplifier output.
Claim 7
Dependent Claim
156 words
A circuit for controlling the power provided from an ac source to a load via a thyristor in response to a control voltage, comprising: a feedback circuit coupled to said load and including: rectifier means for rectifying a signal coupled from said load, a first filter network connected to the input of said rectifier means for shaping said coupled signal and a second filter network connected to the output of said rectifier means for shaping said rectified signal, a capacitor, an isolation amplifier, and means for charging said capacitor via said isolation amplifier to a level established by said rectified signal, the voltage across said capacitor comprising a feedback voltage, a summing amplifier for summing said control voltage and said feedback voltage, a ramp generator providing a signal having a ramp angle established by the output of said summing amplifier, and a trigger circuit for firing said thyristor when said ramp signal reaches a certain value.
Claim 8
Dependent Claim
156 words
A circuit for controlling the power provided from an ac source to a load via a thyristor in response to a control voltage, comprising: a feedback circuit coupled to said load and including: rectifier means for rectifying a signal coupled from said load, a first filter network connected to the input of said rectifier means for shaping said coupled signal and a second filter network connected to the output of said rectifier means for shaping said rectified signal, a capacitor, an isolation amplifier, and means for charging said capacitor via said isolation amplifier to a level established by said rectified signal, the voltage across said capacitor comprising a feedback voltage, a summing amplifier for summing said control voltage and said feedback voltage, a ramp generator providing a signal having a ramp angle established by the output of said summing amplifier, and a trigger circuit for firing said thyristor when said ramp signal reaches a certain value.
Claim 9
Dependent Claim
29 words
A circuit according to claim 6 wherein said feedback circuit includes means for discharging said capacitor with a discharge time constant corresponding to several cycles of said ac source.
Claim 10
Dependent Claim
23 words
A dimmer circuit according to claim 7 together with a capacitor of large value connected to prevent abrupt changes in said control voltage.
Claim 11
Dependent Claim
47 words
A circuit according to claim 6 wherein said means for rectifying comprises a bridge rectifier, wherein said first network comprises a resistor and capacitor series connected across said bridge input, and wherein said second filter network comprises a resistor and capacitor series connected across said bridge output.
Claim 12
Dependent Claim
32 words
A dimmer circuit according to claim 9 wherein the values of said filter network components are selected to achieve a linear function between control voltage and RMS voltage supplied to said load.
Claim 13
Dependent Claim
105 words
A dimmer circuit according to claim 6 wherein said ramp generator comprises: a ramp capacitor, a transistor connected in the charging path to said capacitor, means connecting the output of said summing amplifier to the base of said transistor to control the charging current to said capacitor in response to said output, and means for rapidly discharging said capacitor at the beginning of each ac half cycle comprising; a second transistor connected across said ramp capacitor, and means for clamping off said second transistor during each ac half cycle and for gating on said transistor in unison with the zero crossings of said ac source.
Claim 14
Dependent Claim
41 words
A dimmer circuit according to claim 6, together with a gapped core inductor in series with said ac source, said thyristor device and said load, said inductor having a magnetic flux path including at least two air gaps of different size.
Claim 15
Dependent Claim
101 words
In combination, a dimmer circuit of the type wherein the light intensity from a lamp is controlled by adjusting the firing angle of a thyristor device supplying ac power from a source to said load, and a gapped core inductor in series with said thyristor device and said load to reduce electromagnetic radiation resultant from the current tRansient as said thyristor device is triggered on, said gapped core inductor comprising: a lamination assembly including a central portion, a coil surrounding said central portion, and at least two air gaps of different size in the magnetic flux path including said central portion.
Claim 16
Dependent Claim
101 words
In combination, a dimmer circuit of the type wherein the light intensity from a lamp is controlled by adjusting the firing angle of a thyristor device supplying ac power from a source to said load, and a gapped core inductor in series with said thyristor device and said load to reduce electromagnetic radiation resultant from the current tRansient as said thyristor device is triggered on, said gapped core inductor comprising: a lamination assembly including a central portion, a coil surrounding said central portion, and at least two air gaps of different size in the magnetic flux path including said central portion.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-18 | 1977-08-20 | 1978-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-18 | 1981-08-20 | 1982-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-18 | 1985-08-20 | 1986-02-19 | $7700.00 | Window Closed / Lapsed |