US3506876A - Control circuit for interrupted load energization - Google Patents

Description

April 1970' F. J. ANTONICH 3,506,876

CONTROL CIRCUIT FOR INTERRUPTED LOAD ENERGIZATION Filed Aug. 25, 1966 d 2 V \L/ 3 1a 2 I I 1; Random 1 Random gfi j} Pulse Pulse I Generafor Genercd-or 4! INVENTOR 77. 3 4 fimmcK .1. AA/ra/wcH fl/nAm 1 53/1189.

Afforne 95 United States Patent 3,506,876 CONTROL CIRCUIT FOR INTERRUPTED LOAD ENERGIZATION Fredrick J. Antonich, 2234 S. 81st St., West Allis, Wis. 53214 Filed Aug. 23, 1966, Ser. No. 574,401 Int. Cl. HOSb 37/02, 41/14 US. Cl. 315200 10 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a new and improved control circuit for providing interrupted energization of a load connected to a pulsating current source and particularly to such energization of an incandescent lamp or the like to truly simulate a flickering candle.

In many applications, interrupted energization of a load may be desired. In lighting homes and business establishments, a light may be connected in the circuit through a pulsing system to provide a flickering effect generally for simulating the effect of a candle. Generally, such devices employ a special lamp or are connected through a preset timing device which turns the device on and off at a predetermined fixed rate.

The present invention is particularly directed to a control circuit which energizes a load at a completely random rate with the level of the energization being controllable, if desired. Generally, in accordance with the present invention, the lamp is connected to an alternating current source or a full wave rectified source in series with a silicon controlled rectifier. The rectifier means includes a triggering gate interconnected to a no se generator which in turn is energized from the incoming power lines. The noise generator provides a random energization of the gate and has been found to provide a highly effective random energization of the lamp to provide a high accurate simulation of a candle type flicker.

Generally, the input to the noise generator can be provided with a variable input control to vary the flash flicker level. Further, the circuit can be provided with means to control and essentially vary the light intensity from very low to that generally similar to a normally illuminated or energized lamp.

The drawing furnished herewith illustrates preferred constructions of the present invention in which the above advantages and features as well as others which will be clear from the following description of the drawing. in the drawing:

FIG. 1 is a schematic circuit diagram of a lamp illuminating control circuit constructed in accordance with the present invention;

FIG. 2 is a diagrammatic view of applied voltage, the firing signals and the lamp voltage;

FIG. 3 shows a modification to the circuit of FIG. 1; and

FIG. 4 shows a further modification to the circuit of FIG. 1.

Referring to the drawing and particularly to FIG. 1, a lamp 1 is connected in series with a silicon controlled rectifier 2 to alternating current incoming power lines 3 of the usual distribution system or the like. The lamp may be the well-known incandescent type employed in the home, a Christmas tree light or the like. The illustrated silicon controlled rectifier 2 is a well known device having an anode 4 and cathode 5 connected in series with the lamp 1 to the power lines 3. The rectifier 2 includes a gate 6 adapted to control initiation of conduction through the rectifier. Thus, if a positive current signal is applied to the gate 6 simultaneously with the application of a corresponding positive polarity to the anode 4, the rectifier 2 conducts and then continues to conduct until such time as the current through the anode-cathode circuit drops below the holding current as a result of the reversal during alternate half cycles. In accordance with the present invention, the gate 6 is connected to a noise generator 7 through an emitter follower stage 8.

The noise generator 7 is energized through a voltage dividing network 9 connected across the incoming power lines 3. Generally, the noise generator 7 provides a random pulse output depending upon the input voltage level from the voltage dividing network 9 and the random pulses are applied to the gate 6 through the emitterfollower stage 8.

More particularly, the voltage dividing network 9 includes a diode 10 in series with a variable resistor or potentiometer 11 connected across the power lines 3. Current limiting resistors 12 and 13 are series connected to the opposite sides of the potentiometer 11 in the illustrated embodiment of the invention. The tap 14 of the potentiometer 11 is connected to provide a DC. bias supply to the noise generator 7 and to the emitter follower stage 8. A filter capacitor 15 is connected to the tap 14 and the common line 3.

The illustrated noise generator 7 is similar to that disclosed in the Electronic Equipment Engineers Magazine of July 1964 and generally includes an NPN transistor 17 having a collector 18 connected to the tap 14 in series with a resistor 19 and the emitter 20 connected directly to the common line 3. A resistor 21 in series with a capacitor 22 is connected between the collector 18 and the reference line 3. A Zener diode 23 interconnects the base 24 to the junction of the capacitor 22 and the resistor 21. The circuit is operated near the knee of the Zener diode characteristic at which point the diode 23 exhibits a great amount of noise characteristics. As a result, the bias on the transistor 17 is a wide band noise signal of a generally random amplitude to provide a corresponding output at the collector 18.

The collector 18 is connected to the emitter follower stage 8 through a coupling capacitor 25. The illustrated emitter follower stage is an NPN transistor 26 having a collector 27 connected to the tap 14 of the potentiometer 11 and an emitter 28 connected to the common line 3 in series with an emitter resistor 29. The base 30 is of course connected to the noise generator 7 by the coupling capacitor and a DC. return resistor -A connects the base to the common line 3. The emitter 28 is connected to the gate 6 of a silicon controlled rectifier 2 to connect the gate to cathode circuit across the emitter resistor 29. The emitter follower 26 is connected to the incoming power lines 3 through the voltage dividing network 9 and provides a positive output in phase with the positive signal applied to the anode 4 of the rectifier 5. The emitter follower stage 8 isolates the noise generator 7 from the silicon controlled rectifier 5 to prevent loading thereof.

The operation of the illustrated embodiment of the invention may be summarized as follows. The setting of the potentiometer 11 determines the voltage bias on the noise generator 7 and consequently the operating level of the noise generator 7 as well as the emitter follower 26. The noise generator 7, as a result of the Zener diode 22, provides a wide band random amplitude output, i.e., a plurality of random pulses in the region of the diode breakdown voltage. The series of random pulses are applied to the gate 6 of rectifier 2 via the emitter follower stage 8 and triggers the rectifier 2 at a completely random rate during the alternate half cycles of the incoming power supply.

The wave form of the power supply as applied to the lamp 1 in series with the rectifier 2 is shown at 31 in FIG. 2 with the amplitude shown on the vertical axis and time on the horizontal axis. The random firing pulses 32 applied to the gate 6 of rectifier 2 are shown superimposed on the wave form 31. The firing level of the rectifier 2 is shown by the dashed horizontal line 33. The voltage applied to the lamp 1 is shown by the separate wave form 34 in FIG. 2 having the same time base as the power supply wave form 31.

The rectifier 2 cannot conduct during the negative half cycle of the supply and consequently the firing pulses 32 are only effective during the positive half cycle. Further, only the pulses 32 which have an amplitude in excess of the firing level line 33 and which occur after the minimum firing angle of the rectifier 2 can trigger the rectifier to conduct in accordance with the :known operation of such rectifiers.

In the illustrated embodiment, the first firing pulse 32 of an amplitude in excess of the firing level is shown during the very initial portion of the first positive half cycle of the power supply wave form and thus within the minimum firing angle. Consequently, the rectifier 2 does not fire. As a result, the lamp voltage remains at zero. The subsequent firing pulse 32 in excess of the firing level occurs after the minimum firing angle, fires the rectifier 2 and the balance of the power supply wave form is applied to the lamp 1. Although further effective firing pulses 32 occur during the lamp conduction period, they do not cause any change in operation because the rectifier 2 once fired continues to conduct for the remainder of the half cycle independently of gate signal.

The operation is repeated during the subsequent positive half cycles. As the firing pulses 32 are of a random nature, the eifective firing pulses during such subsequent positive half cycles will normally differ in relative time within the corresponding positive half cycle and therefore provide a different lamp conduction period as shown in wave form 34. This provides a random and varying energization of the lamp 1 to produce a candle type flicker of the illumination.

In summary, lamp 1 is energized whenever a pulse is applied to the gate 6 during the positive half cycle of the main power supply and is held energized until the end of the half cycle when the current drops below the holding level. As the starting point in each half cycle is random, the energization of the lamp 1 is completely random.

The output of the lamp 1 and the rate of flickering can be simultaneously adjusted through movement of the potentiometer tap 14. Thus, as the potentiometer tap 14 is moved to the upper end of potentiometer 11 in the illustrated embodiment of the invention, a larger voltage is applied to the noise generator 7 to cause the lamp to be illuminated a greater portion of the time. Conversely, movement to the other end reduces the illuminating portion during the corresponding half cycle to reduce the illumination level and the rate of flicker.

In FIG. 1, a diode 35 in series with a switch 36 is connected across rectifier 2. Diode 35 is biased to conduct the opposite half cycle when the rectifier is reverse biased. Closing of switch 36 therefore provides increased energization. By closing the switch 36 and simultaneously setting potentiometer 11 to provide sufliciently high bias to generator 7 essentially continues energization of lamp 1 without any noticeable flicker.

A modified embodiment of the invention is shown in FIG. 3 in which the output is a random flashing rather than a flicker as in the circuit of FIG. 1. Corresponding elements in the embodiments of FIGS. 1 and 2 are similarly numbered for simplicity and clarity of explanation. In the embodiment of FIG. 3, a capacitor 37 is connected in parallel with the lamp 1. As a result, the energization of the lamp 1 is a definite relatively slow on-oif cycle of a noticeable period rather than the very rapid on-oif cycle of a flicker. The size of the capacitor 37, although not critical, is generally related to the bias supply to the generator. Thus, it was noted that if the supply was increased, a somewhat larger capacitor was needed.

In FIG. 4, a further embodiment similar to FIG. 1 is shown employing an additional variable illumination control.

In FIG. 4, the lamp 1 is connected to the line 3 before the flicker control circuit and a continuous on switch 38 is connected in parallel with the latter to provide continuous energization if desired. The circuit of FIG. 1 may, of course, be similarly arranged.

Further, in FIG. 4 the alternate or negative half cycles of the power supply are applied to the lamp 1 by a controllable dimmer circuit 39. The dimmer circuit 39 includes a controlled rectifier 40 connected in parallel with the first controlled rectifier 2 and polarized in the opposite direction. A diode 41 in series with a potentiometer 42 and a capacitor 43 are connected across the power line 3 with the junction of the capacitor 43 and potentiometer 42 connected in series with a current limiting resistor 44 to the gate 45 of the second rectifier 40. The diode 41 is polarized in the same direction as the second rectifier 40 and thus provides firing power during the appropriate half cycle. The potentiometer 42 and capacitor 43 provide a timing circuit with the time at which the firing voltage is established at the junction determined by the inserted resistance of the potentiometer 42. Thus, by adjusting the potentiometer 42, the lamp 1 can be variously energized during the negative half cycles to produce a minimum level of illumination upon which the flicker is superimposed.

In carrying out the invention, the circuit and components may be varied as desired. For example, a plurality of lamps or other loads may be series or parallel connected. The rectifier 2 may be of the symmetrical variety such as that sold under the trade name Triac. Further, parallel and oppositely polarized rectifiers may be provided and connected to suitable random pulse means for functioning in the manner previously discussed.

Thus, the present invention has been developed and applied in a highly satisfactory and novel manner to provide a lamp flicker for purposes of simulating a candle. It can, of course, be employed in any applicaiton where it is desired to provide interrupted energization of a load adapted to be controlled by a silicon controlled rectifier or other similar pulse controlled device.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim: 1. In an electronic lamp switching circuit for establlshing a random power supply for intermittent and timed spaced energizing of an incandescent lamp or the like,

alternating current power connection means for connection to an incoming power source,

a triggered electronic switch means having output means for connection to the lamp and the power connection means and having a firing input means to initiate conduction through said output means, said switch means conducting during alternate half cycles, and

random signal generating means connected to said input means for applying a train of random time spaced signals to the input means to trigger said switch means during said half cycle to produce a random time spaced energization of the lamp.

2. The electronic switching circuit of claim 1 wherein,

said random signal generating means is a noise generator.

3. The electronic switching circuit of claim 1 wherein said triggered switch means is a polarized unidirectional conducting means, and said signal generating means includes a solid state semiconductor noise generator.

4. The electronic switching circuit of claim 1 wherein said triggered switch means is a controlled rectifier, and said signal generating means includes a transistor having an input circuit including a Zener diode and supply means for operating the diode in the knee of the breakdown voltage characteristic.

5. The electronic switching circuit of claim 1 wherein said triggered switch means is a triggered rectifying means and said signal generating means includes a transistor having a voltage breakdown means connected between the base to collector circuit, said voltage breakdown means having an operating characteristic including a noise region having a wide frequency wave form, and circuit means connecting the transistor to the power connecting means for energizing said transistor and voltage breakdown means to operate in the noise region of the voltage breakdown means.

6. The electronic switching circuit of claim 1 wherein said triggered switch means is a triggered rectifying means having a firing gate means connected to the signal generating means and said signal generating means includes a grounded emitter transistor having a Zener diode connected in series with an impedance between the base to collector circuit, and a voltage dividing network connecting the transistor to the power connection means for energizing said transistor and Zener diode to operate in the noise region of the characteristic of the diode.

7. The switching circuit of claim 2 having an emitter follower stage connected between the noise generator and the input means.

8. The switching circuit of claim 1 having a capacitor means connected across the output means and thereby in parallel with a load to provide definite on-otf load power.

9. The electronic switching circuit of claim 3 having a second unidirectional triggered conducting means and polarized to conduct in the opposite direction and having an adjustable trigger power means connected to the power supply and including means to limit current flow therethrough to the half cycle, that said first unidirectional conducting means is reverse biased and providing a controlled actuation of the second unidirectional conducting means.

10. The electronic switching circuit of claim 9 wherein said trigger power means is a resistor-capacitor timing circuit.

References Cited UNITED STATES PATENTS 3,070,739 12/ 1962 I-Iansen et al. 307-252 3,209,279 9/ 1965 Kambouris 331-78 3,388,269 6/1968 Bertioli 328-81 3,355,625 11/1967 Ward 3 l5241 OTHER REFERENCES Applications of Electronics, Grob and Kiuer, pp. and 51, 1960.

DONALD D. FORRER, Primary Examiner D. M. CARTER, Assistant Examiner US. Cl. X.R. 307-252, 284

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