US3859591A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Soft turn-on power switching circuit
Assignee: DISPLAY ENTERPRISES Inc
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Filing: 1973-07-02
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Granted: 1975-01-07
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Expires: 1993-07-02
Abstract
Abstract A triac is turned on during each successive half wave of AC in response to zero-crossing signals which generate a composite ramp voltage, including short sawtooth and long ramp voltages, which provides triggering signals after a predetermined threshold is exceeded. When the composite wave is continuously above the threshold, a zero-crossing switch is activated to bypass the AC signal around the soft turn-on part of the circuit, directly into the gate of the triac, to apply all of the AC power to the load after the soft turn-on has been accomplished. A circuit reset component has an input connected to the zero-crossing detector and its output connected to the generators for discharging the generators to their starting condition any time the AC power wave is interrupted, thus insuring soft turn-on even after momentary power interruptions. A regenerative pulse amplifier and a current amplifier are connected between the threshold detector and the triac for generating a triggering signal pulse for the triac and feeding back part of the threshold breaking pulse back into the threshold detector to reinforce it. The circuit can also perform a servo function by connecting an external signal to the circuit reset switch for limiting the level to which the long ramp generator ramp-shaped voltage wave can grow to below the predetermined threshold level whereby the period of operation of the triac is controlled in response to an applied external signal.
Inventors
- 👤 Norman B Saunders
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 23:21
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/13; H03K17/136; G; G05; G05F; G05F1/00; G05F1/10; G05F1/12; G05F1/40; G05F1/44; G05F1/445
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
250 words
A power switching circuit for controlling the application of an AC power source to a load through a thyristor turned on by actuating signals applied to its gate comprising a zero-crossing detector having an input connected to said AC power source for generating a zero-crossing signal each time the AC wave passes through zero, a short ramp generator and a short ramp reset for generating a sawtooth voltage wave in response to each zerocrossing signal, a long ramp generator for generating a rampshaped voltage wave which grows in response to each successive zero-crossing signal, the outputs of said generators being connected to a summer which adds them into a composite ramp wave, a threshold detector connected to said summer for determining when said composite wave rises above predetermined threshold level whereby a turn-on signal is generated, said threshold detector being connected to said gate for turning on said thyristor at earlier times during each successive AC half-cycle wave, a zero-crossing switch connected between said zero-crossing detector and said gate for applying said zero-crossing signal directly to said gate, said threshold detector being connected to said zero-crossing switch for enabling it to be turned on after said composite ramp wave is completely above said predetermined threshold level whereby said zero-crossing signal is bypassed from said short ramp generator and said short ramp reset and said long ramp generator and directed through said zero-crossing switch into said gate for causing said thyristor to apply all of said AC power to said load.
Claim 2
Dependent Claim
250 words
A power switching circuit for controlling the application of an AC power source to a load through a thyristor turned on by actuating signals applied to its gate comprising a zero-crossing detector having an input connected to said AC power source for generating a zero-crossing signal each time the AC wave passes through zero, a short ramp generator and a short ramp reset for generating a sawtooth voltage wave in response to each zerocrossing signal, a long ramp generator for generating a rampshaped voltage wave which grows in response to each successive zero-crossing signal, the outputs of said generators being connected to a summer which adds them into a composite ramp wave, a threshold detector connected to said summer for determining when said composite wave rises above predetermined threshold level whereby a turn-on signal is generated, said threshold detector being connected to said gate for turning on said thyristor at earlier times during each successive AC half-cycle wave, a zero-crossing switch connected between said zero-crossing detector and said gate for applying said zero-crossing signal directly to said gate, said threshold detector being connected to said zero-crossing switch for enabling it to be turned on after said composite ramp wave is completely above said predetermined threshold level whereby said zero-crossing signal is bypassed from said short ramp generator and said short ramp reset and said long ramp generator and directed through said zero-crossing switch into said gate for causing said thyristor to apply all of said AC power to said load.
Claim 3
Dependent Claim
78 words
A circuit as set forth in claim 1 wherein a circuit reset means has an input connected to said zero-crossing detector for making said circuit reset means inoperative when said AC power wave is being provided, said circuit reset means having an output connected to said short and long ramp generators for discharging them to their initial bottom condition when said AC power is off whereby said circuit is reset to bottom starting level upon interruption of power.
Claim 4
Dependent Claim
63 words
A circuit as set forth in claim 2 wherein an external connection means is provided to said circuit reset means for connecting an external signal which limits the level to which said long ramp generator ramp-shaped voltage wave can grow to below said predetermined threshold level whereby the period of operation of said thyristor is controlled in response to said applied external signal.
Claim 5
Dependent Claim
36 words
A circuit as set forth in claim 3 wherein said external signal is a function of the power applied through said thyristor to said load whereby said circuit is constituted to perform a servo control function.
Claim 6
Dependent Claim
40 words
A circuit as set forth in claim 1 wherein a pulse amplifier is connected between said threshold detector and said gate for providing signal pulses to turn said thyristor on when said composite ramp wave is above said threshold level.
Claim 7
Dependent Claim
21 words
A circuit as set forth in claim 5 wherein said pulse amplifier and threshold detector act together in a regenerative manner.
Claim 8
Dependent Claim
25 words
A circuit as set forth in claim 5 wherein a current amplifier is connected between said pulse amplifier and said gate for amplifying said signals.
Claim 9
Dependent Claim
41 words
A circuit as set forth in claim 1 wherein a current amplifier is connected between both said threshold detector and said zero-crossing switch and said gate whereby signals from said threshold detector and said zero-crossing switch to said gate are amplified.
Claim 10
Dependent Claim
46 words
A circuit as set forth in claim 8 wherein said current amplifier includes input and bias circuitry, said zero-crossing switch having a collector loAd, and common components in said current amplifier and said zero-crossing switch comprising both said input and bias circuitry and said collector load.
Claim 11
Dependent Claim
18 words
A circuit as set forth in claim 9 wherein said common components comprise series-connected capacitor and resistor means.
Claim 12
Dependent Claim
53 words
A circuit as set forth in claim 1 wherein a pulse amplifier is incorporated within said threshold detector and said gate, and connection means connecting part of the output of said pulse amplifier back into said threshold detector whereby the strength of the output of said threshold detector to said gate is augmented.
Claim 13
Dependent Claim
58 words
A circuit as set forth in claim 11 wherein a current amplifier is connected between said pulse amplifier and said gate said current amplifier having input and bias circuitry, said pulse amplifier having an emitter-follower load, and common components in said current amplifier and said pulse amplifier comprising both said input and bias circuitry and said emitter-following load.
Claim 14
Dependent Claim
18 words
A circuit as set forth in claim 12 wherein said common components comprise series-connected capacitor and resistor means.
Claim 15
Dependent Claim
120 words
A circuit as set forth in claim 1 wherein said zero-crossing detector comprises a pair of bipolar transistors having collectors tied together, the emitters of each transistor being tied to the base of the other, said AC power source having a phase and a common line, the base of one transistor and emitter of the other being tied to said AC phase line, and the emitter of said one transistor and the base of said other transistor being referenced to said AC common line, said transistors being constructed and arranged to turn off and on each time said AC wave passes through zero whereby said zero-crossing signals are provided at the output of said transistors comprised by said tied collectors.
Claim 16
Dependent Claim
20 words
A circuit as set forth in claim 14 wherein a DC power supply potential is connected to said tied collectors.
Claim 17
Dependent Claim
121 words
A circuit as set forth in claim 14, wherein said zero-crossing detector provides an output signal between said tied collectors and said AC common line whenever the voltage at the connection to said AC phase line is smaller than the threshold voltage of either transistor, one transistor sensing the AC phase line voltage condition during its positive swing, the other transistor sensing said AC phase line voltage condition during its negative swing, both said transistors acting in concert to provide a voltage pulse at said output when said AC phase line is in a narrow zone at zero-crossing, said output voltage pulse starting just prior to, ending shortly after, and spanning the instant of each said AC phase line voltage zero-crossing.
Claim 18
Dependent Claim
14 words
A circuit as set forth in claim 1 wherein said thyristor comprises a triac.
Claim 19
Dependent Claim
41 words
A circuit as set forth in claim 1 wherein a DC power supply potential is connected to said zero-crossing detector, short ramp reset, short ramp generator, long ramp generator, threshold detector, zero-crossing switch, pulse amplifier, current amplifier and circuit reset means.
Claim 20
Dependent Claim
27 words
A circuit as set forth in claim 1 wherein said short and long ramp generators comprise capacitor means and a charging circuit which they share in common.
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) | 1978-01-06 | 1978-07-08 | 1979-01-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-06 | 1982-07-08 | 1983-01-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-06 | 1986-07-08 | 1987-01-07 | $7700.00 | Window Closed / Lapsed |