US3353062A

US3353062A - Flasher device

Info

Publication number: US3353062A
Application number: US443336A
Authority: US
Inventors: Joe A Nuckolls
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1965-03-29
Filing date: 1965-03-29
Publication date: 1967-11-14
Anticipated expiration: 1984-11-14

Description

Nov. 14, 1967 J. A. NUCKOLLS 3,353,062

FLASHER DEVICE Filed March 29, 3.965

" Z1 Z0 22a 90 VAC I [WW/275A" I 06 fl/VzzcM/[z v United States Patent 3,353,062 FLASHER DEVICE Joe A. Nuclrolls, Hendersonville, N.C., assignor to General Electric Company, a corporation of New York Filed Mlar. 29, 1965, Ser. No. 443,336 6 (Ilaims. (Cl. 315157) ABSTRACT 01? THE DISCLOSURE Described is a flasher system comprising a source of alternating current, a first energy storage circuit connected to the source of alternating current for storing energy and voltage at a predetermined level and at a predetermined rate, a discharge flash lamp connected across the first energy storage circuit, a second energy storage circuit connected across the first energy storage circuit for storing at a predetermined rate energy received from the first energy storage circuit, and pulse generating means connected to the second energy storage circuit for discharging the energy stored thereby and delivering the same in a high voltage pulse to the lamp to provide an illumination flash therein.

The present invention relates to flasher devices, and more particularly concerns a control circuit for providing periodic flashing of a gas discharge lamp at a controlled rate.

The flasher circuit of the invention is applicable for use in sign lighting, warning lights, traflic control devices, amusement and novelty lighting, photographic lighting, stroboscope devices, and other devices which make use of periodic light flashes.

Known types of control circuits employed for the above purposes have incorporated electrical relays or mechanical switching components, and as a result have had certain drawbacks, such as relatively large and cumbersome constructions, high power requirements, inadequate life, and mechanical time-constant limitations.

It is an object of the invention to provide an improved flasher circuit, especially for use with gas pressure lamps, which avoid the above disadvantages of the prior art devices.

It is a particular object of the invention to provide a control circuit for gas discharge lamps which may operate the lamps with adjustable energy flash levels to obtain differing brightness, which provides controllable intervals between light flashes, and which is simple in construction and relatively inexpensive to manufacture.

It is another object of the invention to provide a control flasher circuit of the above type which is readily applicable for combination with independently operable devices and circuits which control the operation of the flasher circuit.

Other objects and advantages will be apparent from the following description and the appended claims.

To attain the above objects, there is provided in accordance with a broad aspect of the invention, a flasher system comprising a source of alternating current, a first energy storage circuit connected to the source of alternating current for storing energy and voltage at a predetermined level and at a predetermined rate, a discharge flash lamp connected across the first energy storage circuit, a second energy storage circuit connected across the first energy storage circuit for storing at a predetermined rate energy received from the first energy storage circuit, and pulse generating means connected to the second energy storage circuit for discharging the energy stored thereby and delivering the same in a high voltage pulse to the lamp to provide an illumination flash therein.

The invention will be better understood from the fol- Patented Nov. 14, 1967 lowing description taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a schematic circuit diagram of a lamp flasher control circuit constructed in accordance with the invention; and

FIGURE 2 shows a modification of the FIGURE 1 circuit wherein the circuit is combined with an independently operable actuating circuit for operation thereby.

Referring now to the drawing, and particularly to FIG- URE 1, there is shown a controlled lamp flashing circuit comprising an alternating current source 1 having in series therewith resistor 2 connected between series connected capacitors 3 and 4. Rectifier 5 connected between A-C source 1 and capacitor 3 is arranged to pass current only toward capacitor 3, whereas rectifier 6 connected between A-C source 1 and capacitor 4 is arranged to block current directly between A-C source 1 and capacitor 4. This arrangement of rectifiers, capacitors and resistor serves as rectifier-voltage doubler circuit 7 whereby half the total resulting direct current voltage is across each capacitor 3 and 4. As will be seen, the respective capacitors, by virtue of the arrangement shown, are charged on alternate half cycles to the peak of the supply voltage. Where a volt A- supply is used, as in typical cases, each capacitor will be charged to about volts, and the combined voltage across capacitors 3 and 4 will thus be about 340 volts.

Resistor 2 serves to limit the rate of charge buildup on capacitors 3 and 4 and also to isolate or bufi er the latter capacitors from voltage source 1 during the discharge of capacitors 3 and 4 as described hereinafter.

Rectifiers

5 and 6 are typically low power semi-conductor diodes, but may in appropriate cases be high vacuum or gas diode rectifiers. While in the usual application the AC source is 120 volts, higher A-C voltages may be used where desirable or necessary.

Connected in series across voltage doubler circuit 7 by means of

conductors

14 and 15 are a gas discharge lamp L and autotransformer 8 serving as a step-up pulse transformer, the latter being connected to the positive side of doubler circuit '7. Typically, lamp L is a high gas pressure flash lamp containing Xenon, argon or the like.

An ignition circuit comprising discharge capacitor and resistor It} in series therewith are connected across voltage doubler circuit 7, and capacitor 9 is connected to pulse transformer 8 such that the higher number of winding turns of the latter, i.e., the secondary winding, is connected to lamp L. The connection of capacitor 9 to transformer 8 is such as to provide the correct pulse polarity and voltage step-up. In the arrangement shown, capacitor 9 is charged through resistor 10 from the 340 volts across capacitors 3 and 4. A neon glow lamp 11 (or equivalent voltage sensitive switch) is connected between the primary winding of transformer 8 and the junction of capacitor 9 and resistor 10. Glow lamp 111 in the embodiment shown is designed to become conductive and fire at about 270 volts, and upon such firing forms a discharge loop with capacitor 9 and the primary winding of pulse transformer 8.

T 0 provide for automatic operation of the flash circuit only during hours of darkness, a photoelectric control may be added. For this purpose, in the embodiment shown a photoelectric cell 12, such as a cadmium sulfide cell, is connected across neon glow lamp 11 so that during daylight hours, when the resistance of photoelectric cell 12 is low due to exposure to light, photocell 12 prevents the voltage across neon lamp 11 from reaching breakdown potential, and thus no pulse is applied to transformer 8.

A high frequency by-pass capacitor 13 may be arranged in parallel across the operating circuit as shown, to insure that the input to pulse transformer 8 remains at the A-C ground, particularly if discharge capacitors 3 and 4 exhibit high self-impedances at'the pulse frequency. If the impedance of capacitors 3 and 4 during the pulse interval is sufliciently low, by-pass capacitor 13 may not be necessary.

In the operation of the circuit described,- capacitors 3 and 4 in the voltage doubler circuit 7 are charged by the 120 volt A-C source to a total voltage of about 340 volts, the time of voltage build-up being dependent on the resistance value of resistor 2, which is typically about 500 ohms. Capacitor 9 is charged by capacitors 3 and 4 through resistor 10, the rate of charge build-up being dependent on the value of the latter resistor, which is so chosen that the time for charge build-up on capacitor 9 is longer than that required for charge build-up on capacitors 3 and 4. During the hours of darkness, the resistance of photocell 12 is high, and accordingly neon glow lamp 11 will fire when the charge on capacitor 9 reaches about 270 volts. Capacitor 9 thus discharges through the primary of transformer 8 delivering a pulse thereto. As a result, a high voltage starting pulse, e.g., at 1-25 kv., is induced across the secondary of transformer 8 and impressed,

across flash lamp L, so that lamp L becomes conductive by ionization of the gas therein. As the voltage across lamp L falls, the higher energy on the series connected capacitors 3 and 4 is delivered to the lamp, causing a momentary flash of light therein. When this energy is dissipated, the arc is extinguished and the described sequence is repeated.

The rate at which the flash is repeated can be adjusted by employing lower resistances for resistor 2 to obtain faster rates of flash repetition, and using higher resistances for reducing the flash rate.

Resistor controls the rate of charge build-up on capacitor 9, and preferably is of relatively high resistance (typically about 5.6 megohms) to provide de-coupling of capacitor 9 from the D-C voltage source during the in-. terval of discharge from capacitor 9.

FIGURE 2 illustrates how the flasher control circuit described in connection with FIGURE 1 may be combined with an independently operable circuit which controls the operation of the control circuit. FIGURE 2 shows the flasher control circuit in somewhat modified form connected to the output of a known counting device circuit whereby flash lamp L operates in response to signals generated by the counter circuit. Thus, in the combination, lamp L flashes when the counter output is energized to illuminate an incandescent indicator lamp which provides for reading a particular number adjacent thereto (not shown). The counter circuit includes an output

loop comprising conductors

20 and 21 across which a voltage of 90 volts A-C is provided in the particular counter circuit involved. Connected across

conductors

20, 21 in the counter output loop is a silicon controlled rectifier (SCR) 22 having a gating circuit 22a actuated by means (not shown) forming a part of the counter circuit, and an incandescent indicator lamp 23 in series with SCR 22. In the normal operation of the counter circuit, when SCR 22 is energized through actuation of gating circuit 22a, indicator lamp 23 is illuminated by current passing through SCR 22. When SCR 22 is deenergized, indicator lamp 23, which has a low resistance level, does not glow, and the 90 volts A-C potential appears across SCR 22. In accordance with the invention, the flasher control circuit incorporating flash lamp L may be combined with the counter output circuit to provide for flashing of lamp L when indicator lamp 23 is energized by operation of SCR 22. For this purpose, there is connected across SCR 22 a charging circuit comprising discharge capacitor 24, the primary 25a of pulse transformer 25, and resistor 26 arranged in series, whereby capacitor 24 becomes charged by the 90 volt A-C potential across

conductors

20, 21 during the period when SCR 22 is de-energized, the charge build-up time being governed by the resistance level of resistor 26. Resistor 27 is arranged in series between capacitor 24 and transformer primary 25ato provide an over-damped oscillatory discharge through the latter.

Diode, 28 is arranged in series between SCR 22 and indicator lamp 23 to permit charging of capacitor 24 on alternating half cycles of the A-C supply voltage and to block discharge from capacitor 24 during charge build-up, while allowing normal half cycle operation of the counter circuit. Diode 29 is connected between the output of SCR 22 and transformer primary 25a and in shunt with resistor 26,-so that when SCR 22 fires, the discharge current from capacitor 24 passes through SCR 22 and diode 29 to transformer primary 25a to provide a pulse surge.

In the flasher control circuit shown in FIGURE 2, wherein like numerals designate like components shown in FIGURE 1, the secondary winding 25b of pulse transformer 25 is connected to gating circuit 30a of SCR 30, which replaces neon glow lamp 11 in the pulse generating discharge loop containing discharge capacitor 9. Transformer 25 is a step-down transformer with a ratio of turns, for example, of four to one between the primary and secondary windings, -so as to provide a low voltage pulse to gating circuit 30a. Where necessary to protect SCR 30 from high peak reverse voltages from the oscillatory circuit including capacitor 9 and the primary of transformer 8 during the discharge of capacitor 9, diode 31 is connected across SCR 30 as shown. If SCR 30 has incorporated therein the so-called controlled avalanche" feature, diode 31 may be omitted. In other respects, the remainder of the flasher control circuit in FIGURE 2 is essentially the same as that shown in FIGURE 1 and described previously in reference thereto.

In the operation of the arrangement shown in FIG- URE 2, during the period when the counter circuit output is deenergized, capacitor 24 becomes charged to about volts. When SCR 22 is fired due to triggering of its gating circuit 22a by operation of the counter, the charge on capacitor 24 is applied through SCR,22 and diode 29 to transformer primary 25a. At the same time, current passes through indicator lamp 23 causing it to illuminate its adjacent numeral. The pulse transmitted by discharge of capacitor 24 through transformer 25 is applied to gating circuit 30a in the form of a high frequency, low voltage surge over-damped, and this triggers the operation of SCR 30. With the capacitor 9already charged to approximately 340 volts by operation of the flasher control circuit as described in connection with FIGURE 1, firing of SCR 30 results in discharge of capacitor 9 through the primary of transformer 8 to provide a high voltage pulse via the secondary of transformer 8 to lamp L, causing the latter to flash in the manner already explained, and the lamp flash coincides with the illumination of indicator lamp 23. Thus, the operation of lamp L is tied directly to the operation of the counter circuit.

In order to avoid undesired short time reoccurrent,

reference to particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually departing from the scope of the invention. Therefore, the appended claims are intended to cover all such equivalent variations as come within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A flasher system comprising, in combination, a source of alternating current, a first energy storage circuit connected to said source of alternating current for storing energy and voltage at a predetermined level and at a predetermined rate, a discharge flash lamp connected across said first energy storage circuit, a second energy storage circuit including a discharge capacitor connected across said first energy storage circuit for storing at a predetermined rate energy received from said first energy storage circuit, pulse generating mean connected to said second energy storage circuit and comprising a glow lamp having a predetermined voltage breakdown level and a step-up pulse transformer, said glow lamp, said discharge capacitor and the primary of said transformer forming a discharge loop for automatically generating a pulse at said voltage breakdown level, the secondary of said pulse transformer being connected to said flash lamp for delivering said pulse thereto at high voltage to provide an illumination flash therein, and photocell means connected across said glow lamp for controlling the operation thereof in response to ambient light level.

2. A flasher system comprising, in combination, a first energy storage circuit comprising a voltage doubler circuit including a pair of series connected discharge capacitors, an alternating current source and a resistor connected in series to the junction of adjacent terminals of said discharge capacitors, and rectifier means connected respectively between the other terminals of said discharge capacitors and said alternating current source, said rectifier means being oriented to pass current from said alternating current source on alternate half cycles to different ones of said discharge capacitors, a discharge flash lamp connected to said voltage doubler circuit in series discharge relation to said pair of discharge capacitors, a second energy storage means connected across said voltage doubler circuit for receiving and storing energy therefrom, and pulse generating means connected to said second energy storage means for discharging the energy stored thereby and delivering the same in a high voltage pulse to said lamp to provide an illumination flash there- 1n.

3. A flasher system as defined in claim 2, said pulse generating means including controlled switch means, and independently operable circuit means connected to said controlled switch means for actuating the same to operate said flash lamp in response to the operation of said independently operable circuit means.

4. A flasher system as defined in claim 3, wherein said controlled switch means comprises a semi-conductor controlled rectifier having a control electrode for operating the same for discharging the energy stored by said second energy storage circuit, and pulse forming means connected to said control electrode for operating said controlled rectifier, said independently operable circuit means including second controlled switch means and connected to said pulse forming means for actuating the latter means.

5. A flasher system as defined in claim 4, said pulse forming means comprising a discharge capacitor, resistor and step-down pulse transformer connected in series, the secondary of said pulse transformer being connected to said control electrode for operating said controlled rectifier, said second controlled switch means of said independently operable circuit means being connected to said pulse forming means.

6. A flasher system comprising, in combination, an alternating current source, a first energy storage circuit connected to said alternating current source for storing energy and voltage at a predetermined level and at a predetermined rate, a discharge flash lamp connected across said first energy storage circuit, a second energy storage circuit comprising a first discharge capacitor and a first resistor connected in series across said first energy storage circuit for storing at a predetermined rate energy received from said first energy storage circuit, pulse generating means comprising a semi-conductor controlled rectifier having a control electrode for operating the same, and a step-up pulse transformre, said controlled rectifier, the primary of said transformer, and said first discharge capacitor forming a discharge loop for generating a pulse upon operation of said controlled rectifier, the secondary of said pulse transformer being connected to said flash lamp for delivering said pulse thereto at high voltage to provide an illumination flash therein, protective rectifier means connected across said controlled rectifier to bypass reverse current in said discharge loop, pulse forming means comprising a second discharge capacitor, a second resistor, and step-down pulse transformer connected in series, the secondary of the latter transformre being connected to said control electrode for operating said controlled rectifier, and independently operable circuit means including controlled switch means connected to said pulse forming means for actuating said pulse forming means for operating said flash lamp in response to the operation of said independently operable circuit means.

References Cited UNITED STATES PATENTS 2,622,229 12/1952 Lord 3 15--152 2,799,809 7/ 1957 Lautenberger 315-209 2,976,461 3/ 1961 Dilger et al. 3 l5-205 3,024,386 3/ 1962 Chauvineau 315-183 3,130,349 4/1964 Mallory 315-151 3,134,048 5/1964 Wolflramm et a1. 315-206 3,221,183 11/1965 White 30788.5 3,246,201 4/ 1966 Michalski 31512O 3,249,807 5/1966 Nuckolls 315199 JOHN W. HUCKERT, Primary Examiner. D. O. KRAFT, R. F. POLISSACK, Assistant Examiners.

Claims

1. A FLASHER SYSTEM COMPRISING, IN COMBINATION, A SOURCE OF ALTERNATING CURRENT, A FIRST ENERGY STORAGE CIRCUIT CONNECTED TO SAID SOURCE OF ALTERNATING CURRENT FOR STORING ENERGY AND VOLTAGE AT A PREDETERMINED LEVER AND AT A PREDETERMINED RATE, A DISCHARGE FLASH LAMP CONNECTED ACROSS SAID FIRST ENERGY STORAGE CIRCUIT, A SECOND ENERGY STORAGE CIRCUIT INCLUDING A DISCHARGE CAPACITOR CONNECTED ACROSS SAID FIRST ENERGY STORAGE CIRCUIT FOR STORING AT A PREDETERMINED RATE ENERGY RECEIVED FROM SAID FIRST ENERGY STORAGE CIRCUIT, PULSE GENERATING MEANS CONNECTED TO SAID SECOND ENERGY STORAGE CIRCUIT AND COMPRISING A GLOW LAMP HAVING A PREDETERMINED VOLTAGE BREAKDWON LEVEL AND A STEP-UP PULSE TRANSFORMER, SAID GLOW LAMP, SAID DISCHARGE CAPACITOR AND THE PRIMARY OF SAID TRANSFORMER FORMING A DISCHARGE LOOP FOR AUTOMATICALLY GENERATING A PULSE AT SAID VOLTAGE BREAKDOWN LEVEL, THE SECONDARY OF SAID PULSE TRANSFORMER BEING CONNECTED TO SAID FLASH LAMP FOR DELIVERING SAID PULSE THERETO AT HIGH VOLTAGE TO PROVIDE AN ILLUMINATION FLASH THEREIN, AND PHOTOCELL MEANS CONNECTED ACROSS SAID GLOW LAMP FOR CONTROLLING THE OPERATION THEREOF IN RESPONSE TO AMBIENT LIGHT LEVEL.