US3829830A

US3829830A - Circuit for switching d. c. power

Info

Publication number: US3829830A
Application number: US00235053A
Authority: US
Inventors: J Scarpino
Original assignee: Hope Tronics Ltd
Current assignee: Hope Tronics Ltd
Priority date: 1972-03-16
Filing date: 1972-03-16
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13

Abstract

A circuit for delivering pulsed or constant power to a set of loads, particularly headlamps whose flashing serves as an alert. A number of transistor amplifiers serves as switches to switch moderately high power to the loads from a D.C. source. Two alternating, out-of-phase outputs of a continuously running astable multivibrator bias associated transistor switches into and out of conduction. This causes out of phase pulsed or flashing actuation of loads. An overriding, continuous bias potential, supplied to some, all, or none of the transistor switches, causes steady energization of some, all, or none of the loads. A remote switch controls the delivery of the continuous bias potential to selected transistor switches. When less than all loads operate continuously, the remaining pulsed loads include loads from both out-of-phase groups.

Description

United States Patent 1191 O A e Scarpino Aug. 13, 1974 [54] CIRCUIT FOR SWITCHING D. C. POWER 3,732,540 5/1973 Platte 340/83 X [75] Inventor: John J. Scarpino, Garden City, NY. FOREIGN PATENTS OR APPLICATIONS [73] Assignee; Hope-Trunks, Limited, Hempstead, 1,295,979 5/1962 France 340/83 NY. [22] Filed: Man 16 1972 Primary Examiner-John W. Caldwell 1 Assistant Examiner-Marshall M. Curtis [21] Appl. No.: 235,053

57 ABSTRACT [52] US. Cl 340/81 R, 340/76, 340/83 51 1m. (:1. G08b 5/38 A for dellvermg Pulsed or Constant POWer a 58 Field of Search 307/41, 247 R, 247 A, 315; Set of loads, Particularly headlamps whose flashing 3 5 200 A, 09 2 25 340/67, 74, serves as an alert. A number of transistor amplifiers 76, 81 R, 81 F, 82 83 serves as switches to switch moderately high power to the loads from a DC. source. Two alternating, out-of- 5 References Cited phase outputs of a continuously running astable multi- UNITED STATES PATENTS vibrator bias associated transistor switches into and I out of conduction. This causes out of phase pulsed or 2,663,806 12 1953 Darlmgton 307 315 flashing actuation ofloads An overriding Continuous 2,891,195 6/1959 Smyth 340/81 R X bias 0t I d t n f th 2,994,013 7/1961 Skellett 315/209 R x P Supple 0 some a or 9? e 3 440 489 4/1969 Davidson et 315/209 R transistor swltches, causes steady energization of 314791641 ll/l969 Summers 340/82 x some, "Oneof the loads- A-femote switch 3,576,527 4/ 1971 Howard 340/6 trols the delivery of the continuous bias potential to 3,532,930 6 1971 .Marks 340 82 x selected transistor switches. When less than all loads 3,584,257 6/l97l Adams 340/33l UX operate continuously, the remaining pulsed loads in- 3,609,681 9/1971 Saul 340/76 clude loads from both out-of-phase groups. 3,646,359 2/1972 Bolinger 307/247 A X 3,671,802 6/1972 Ballou 340/76 X 4 Claims, 1 Drawing Figure I: f C -5'4 fi m l a 52 '53 i l 1 ER 47 4/ 44 4: L

g 47 1 45 3 42 5+ 4 11 l l 1 l PATENTEDm: 13 m4 Q g i q CIRCUIT FOR SWITCHING D. C. POWER BACKGROUND OF THE INVENTION I This invention relates to a circuit for controlling the alternate application of constant or pulsed power to several load devices, and more particularly to a circuit that selectively causes all, less than all, or none of the load devices to be constantly energized while the remainder is pulsed.

For emergency vehicles, police cars, fire vehicles, ambulances, and the like, flashing headlamps are known to be effective in alerting the public, drivers and pedestrians. In other instances, as well, the ability to energize one or more electrical devices to receive power at a constant level or at pulsed or alternating rates may be desired. Examples include audible devices, such as horns, bells, and buzzers.

Drivers of emergency vehicles have been known to flash the headlamp as a warning by rapidly operating the off-on switch by hand. This is a dangerous practice in a situation demanding the drivers full attention and use of both hands. Some automatic flashing arrangement is clearly desirable.

Circuits using repeatedly opened and closed mechanical switches have been proposed. Mechanical switching defects are only too well known, particularly at moderately high current levels. For example, dirty or pitted switch contacts affect both the life and reliability of mechanical switches. Sparking, when even moderate currents are switched, may limit the use of mechanical switches. This latter defect can be dangerous in the presence of explosive or flammable materials, for example gasoline at the scene of an accident.

Thermally actuated switches have been tried. In addition to the defects outlined above, which result from repeated mechanical making and breaking of the contacts, thermal actuation suffers further deficiencies. The rate of flash cannot adequately be controlled, and when thermal actuation depends on heat generated by the current being switched, lamp failure, the drain on the battery from other ordinary loads, and any other occurrence affecting the current being switched change the lamp flashing rate.

Particularly in a circuit that controls the energization of emergency vehicle lights, the ability to cause pulsating operation of some and constant operation of others is desirable. If four high beams are used these may be operated for normal high beam use. Two may be so operated leaving two to flash, or all four may be flashed. The low beams can be left unaffected.

In addition, alternately flashing lamp pairs are particularly effective alerts. Out-of-phase alternating energization is therefor another important feature in a circuit which is to be used to flash lamps.

. SUMMARY OF THE INVENTION A control circuit according to this invention provides each of the desirable features and capabilities just discussed. Briefly, plural transistor switching arrangements connected between plural loads and a source are selectively activated to energize selected loads. An alternating bias source repeatedly applies bias voltages appropriate to cause pulsed energization of the loads by repeated alternations of the transistor switching arrangements between conduction and nonconduction. A manually operable switch applies a constant bias voltage to all, less than all, or none of the transistor switching arrangements. The manual switchs constant bias voltage overrides the pulsed signal wherever applied and causes constant or uninterrupted energization of a load.

The multivibrator has out-of-phase outputs.which provide out-of-phase or wig-wag flashing if applied to transistor switches controlling a pair of lamps. The steady rate at which the multivibrator alternates is independant of the loads or the currents being switched. The transistor switching arrangement offers greater reliability than mechanical switching, and of course contact sparking is precluded. Amplifier connections for the transistor switches, Darlington amplifiers in the specific preferred embodiment that follows, give the transistor switches a current capability adequate to the initial high current surge characteristic of cold headlamp filaments.

The use of an astable multivibrator permits pulse rate adjustment. This adds to the flexibility of the circuit. Perhaps more importantly this permits the rate at which current is switched to a particular set of lamps to be adjusted so that the off time is insufficient to cause excessive filament cooling. Repeated excessive surges are eliminated and significantly less power dissipated. Because the transistor switching arrangements require only low level signals for actuation, the power consumption of the control circuit, itself, is very low.

The manually operable switch controls the mode in which the circuit operates. If vehicle lamps are controlled, the switch is remote, located in the vehicle's passenger compartment. Steady energization of all loads occurs when the switch applies the constant overriding bias voltage to all transistor switches. When less than all loads are to be pulsed the manual switch supplies the overriding bias voltage only to those transistor switches which supply loads to be operated continuously, and the multivibrator outputs drive the remaining transistor switches, alternately switching the remaining loads off and on in a pulsed or flashing manner. If all loads are to be pulsed,the manual switch supplies no signal to any transistor switch.

When four headlamps are controlled and two or four can flash, ablocking diode connected between the associated pairs of transistor switches affords a preferred arrangement to supply the overriding bias to the two .or four lamp control transistor switches. Supplied to one terminal of the diode, the bias voltage switches on less than all transistor switches; supplied to the other, all transistor switches conduct. A single two-wire connection to the manual switch in the passenger compartment then simplifies the installation of the circuit. And because the manual switch supplies only low currents to control the transistor switches, light wiring only is brought into the passenger compartment, making switch location and installation easy. g

The control circuit according to the invention also is capable of switching a range of voltages and currents, lending versatility to the circuiLFinally, with appropriate selection of PNP or NPN transistors and associated circuit components, well within the ordinary artisans capabilities, the control circuit may be used with either a positive or a negative D.C. supply.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of the invention, referaccording to the invention as used to control the headlamps of a vehicle.

DESCRIPTION OF EXEMPLARY EMBODIMENT In the exemplary embodiment shown in the drawing, a control circuit arranged according'to the invention is generally designated by the numeral 10. A battery 11 serves as the DC power source for the control circuit of the invention. The battery 11 maybe an ordinary vehicle battery, serving all of its ordinary uses in addition to supplying the control circuit according to the invention. The positive terminal of the battery 11 is connected in series with an off-on headlight control switch 12 which is the ordinary headlight control switch located on a vehicle's dashboard and which is manually closed by a driver to light a vehicles headlights. Also in series with the battery 11 and the headlight switch 12 is a high beam switch 14. The high beam switch 14 may be conventional, being ordinarily available to operate the high beam once the headlights have been turned on by closing the headlight switch 12.

Normally, the switch 14 is connected to each high beam lamp or to the high beam filaments of each dual filament lamp and serves directly to activate the vehicles high beams. However, in the present invention, the switch 14 supplies power to the control circuit from the contact 14a. The actual application of voltage to the high beam lamps is controlled by the control circuit in the manner described below, once the headlight switch 12 has been closed and the high beam switch 14 has switched power to the contact 140 in the high beam on position.

v The circuit 10 controls four lamps, 16, 18, 20, and 22. Forthe" purpose of this discussion,

lamps

16 and 18 shall be called the inboard pair, lamp 16 being the left inboard lamp, and lamp 18 being the right inboard lamp.

Lamps

20 and 22 shall be referred to as the outboard pair, lamp 20 being the left outboard lamp and 22 the right outboard lamp. Also the lamps l6 and 18 are illustrated as single filament high beam lamps.

Lamps

20 and 22 are dual filament high and low beam lamps with low beam filaments 23 and 24 in addition to the high beam filaments 25 and 26. Voltage to energize the low beam filaments is supplied from contact 14b of the high beam switch 14. This arrangement then leaves the low beam operation unchanged.

' components.

In the switching-arrangement 15, a pair of transistors 01 and Q2 are connected with the collectors of each transistor in common. The emitter of transistor O1 is connected with line 27 which is '+l2 volts D.C. when switches 12 and 14' are closed-Line 27s 12 volt potential is connected through a resistor 28 to both the base of the transistor Q1 and the emitter of transistor'QZ. The base connection 30 of the transistor Q2 serves as a trigger or gate connection for the switching arrangement l5, effecting conduction through bothQl and Q2 when an appropriate bias potential is applied there. So connected, the two transistors form a Darlington amplifier arrangement.

The biasing of the base to emitter voltages of the transistors Q1 and O2 is such that the transistors Q1 and Q2 operate in either the cutoff or the saturation regions. Hence the Darlington amplifiers act essentially as switches. The parallel conduction of the transistors Q1 and Q2 makes this arrangement particularly suitable for headlight control, or for that matter the control of other moderately high current incandescent lamps. A current capability of 10 amperes is easily attained with commercially available transistors, and this current capability will be adequate to the current surge which ordinarily occurs when energizing cold incandescent lamp filaments.

A potential at or near ground level applied to the base 30 of the transistor 02 causes conduction of the transistor switch 15. Therefore, as used herein, bias potential" or bias voltage" is not meant to exclude a zero volt connection. A higher positive voltage applied to the base connection 30 or an open base connection there blocks conduction through the transistor switch 15.

Bias potentials appropriate to cause conduction may be applied to the base connection 30 via either of two gate paths. Diode 32 and resistor 33 form one such path; diode 35 and resistor 36 form another. These paths provide lamp energizing circuit control connections. A ground or near ground connection to either of these paths will cause the transistor switch 15 to conduct and lamp 16 to light.

Each of the remaining transistor switches 17, 19, and 21 cooperate with identical gate paths. Like the individual components of the transistor switching arrangements, then, the associated gate paths have like diodes and resistors designated by similar reference numerals.

An astable multivibrator 40 operates continuously when switches 12 and 14 are closed to activate the control circuit 10. The multivibrator 40 controls the flashing rate ofthe lamps when they are flashed. The circuitry of the astable multivibrator is conventional and requires no detailed description other than the general explanation that follows.

In the multivibrator 40, a pair of transistors 03 and 04 are driven alternately into saturation and cutoff. As the transistor O3 is in saturation, the transistor O4 is in cutoff and vice versa. The rate at which the two transistors switch into and out of conduction is selectively controlled by RC networks in the base circuit of the respective transistors. Adjustment of the

variable resistors

41 and 42 alters the time constants of the RC networks made up of those resistors and their respective associated

capacitors

44 and 45. In addition, a pair of capacitors 47 and 48 serve conventionally as filters, and a pair of resistors 49 and 50 establish the collector bias for the transistors Q3 and Q4, respectively. Resistor 52 is a current limiting resistor and capacitor 53 smoothes the reference voltage at line 54, holding that voltage substantially independent of momentary current changes through the multivibrator.

The reference voltage at the line 54 is nearly ground potential. Conduction of the transistor O3 in the multivibrator 40 biases the transistor switches and 19 into conduction. Conduction of the transistor Q3 opens a current path from the base connection 30 through the first control connection to the energizing circuit, at the diode 35 and resistor 36, to bias the transistor switch 15 into conduction and simultaneously opens a current path from the base connection 30 through the first control connection to the transistor switch circuit 19, via diode 35 and the resistor 36" to bias switch 19 into conduction. Conduction of the transistor Q4 acts similarly to bias transistor switches 17 and 21 into conduction. Because the outputsof the multivibrator 40 are out of phase, the left transistor switches 15 and 19 alternate between conducting and blocking'conditions in out-of-phase relationship to the two right transistor switches 17 and 21. Hence under the control of the multivibrator 40 lamps l6 and flash in out-of-phase relationship to the

lamps

18 and 22. p

The control of the modes of operation of the control circuit 10 is provided by a manual mode selector switch 60. This may be any of a number of commercially available manually operable multiple connection switches. For purpose of illustration, the switch 60 is shown to include three fixed

contacts

61, 62 and 63, and a manually operable wiper arm 64, connected to ground. In the embodiment shown, the switch 60 is the only additional element which must be made available to the vehicle operator.

With the movable wiper arm 64 located in contact with the fixed contact 61, control of the four

transistor switching arrangements

15, 17, 19, and 21 is left entirely to the astable multivibrator 40. This then is the first mode of operation in which all four

high beam lamps

16, 18, 20, and 22 flash.

A second lamp control mode occurs when the movable wiper arm 64 of the switch 60 contacts the fixedcontact 62 as shown. A ground connection is applied via line 66 to resistors 33" and 33", which with diodes 32" and 32", respectively, form the second control connections of the two switching circuits via gate paths to the base connections 30" and 30" of transistor switches 19 and 21. Now the path to ground from the base connections 30" and 30" biases transistor switches 19 and 21 into conduction continuously, overriding the pulsating or alternating control of transistors Q3 and Q4 of the multivibrator 40.

Lamps

20 and 22 are thus continuously or steadily on in this mode. No continuous path to ground is provided to the

base connections

30 and 30 of the transistor switches 15 and 17, a central blocking diode 67 preventing conduction to ground via the line 66. Hence the first set of switches 15 and 17 continue alternately to conduct, lamps l6 and 18 alternately to flash.

Finally, with the movable wiper arm 64 contacting the fixed contact 63 of the mode selector switch 60, a path to ground is completed through line 68, and the second of the two control connections for each transistor circuit, from the base connections 30 and 30' of transistor switches 15 and 17, and from the base connections 30" and 30" of the transistor switches 19 and I switch 60 is left with its wiper arm 64 on the fixed 21, as well, the blocking diode 67 now being forward contacts 63, the lights are turned on as usual by closing the headlight switch 12, and the high beams are activated in their normal fashion by closing switch 14. Once this is done, the other two modes of operation are available by manual adjustment of the switch 62 to its two positions.

Additional vehicle lamps may be driven from the various transistor switches as well, and many other uses of the control circuit 10 are available. The embodiment of the present invention that is described above is intended to be merely exemplary, and those skilled in the art will be able to make numerous variations and modifications of it without departing from the spirit and scope of the invention. All such variations and modifications embodying the invention are intended to be included within the scope of the invention as defined in the appended claims.

I claim:

1. A multiple lamp energizing circuit having three lamp energizing modes and including:

a. a first set of at least 2 lamp energizing circuits,

b. a second set of at least 2 lamp energizing circuits,

c. each of said lamp energizing circuits including control means responsive to an electrical input signal.

for activating the energizing circuit and each hav-' ing first and second control connections, d. a means for producing two alternating out-ofphase outputs at first and second output terminals,

energizing circuits and conductive in one direction between first and second connections,

g. said first output terminal of said alternating producing means being connected to the first control connection in at least one and less than all energizing circuit control means of said first and second sets of energizing circuits,

h. said second output terminal of said alternating output producing means being connected to the first control connection of the remaining energizing circuit control means of both sets of energizing circuits,

i. the second control connection of all of the first set of energizing circuits being connected to the first connection of the unidirectional conductor means and to said first switch output,

j. the second control connection of all of the second set of energizing circuits being connected to the second connection of the unidirectional conductor means and to the second switch output,

whereby in operation, (l) with the selector switch bias applied to neither switch output, said alternating output means activates energizing circuits of both sets that are connected with the first input terminal of the alter-.

nating output producing means, alternately and out of phase with the remaining energizing circuits of both sets that are connected with the second output terminal of the alternating output producing means, (2) with the switch bias connection connected'to the first switch output, an overriding bias is applied to the second control connections of all of the circuits in the first set and blocked by the unidirectional conductor means from the circuits of the second set, to continuously activate only the circuits of the first set while the second set continues to be alternately activated out-of-phase, and (3) with the bias connection connected to the second switch output, the overriding bias is applied to the second control connections of all of the second set of circuits and, via the unidirectional conductor means, to the second control connections of the first set to cause all circuits continuously to be activated.

2. The lamp energizing circuit according to claim 1 wherein the means for producing first and second outof-phase electrical output signals is a continuously run- 8 ning astable multivibrator.

3. The lamp energizing circuit according to claim 1, wherein energizing circuitsfrom. each of the two lamp energizing circuit sets controlled by the two out-ofphase outputs are connected with lamps on the opposite sides of a vehicle to cause a distracting out-ofphase flashing.

4. The lamp energizing circuit according to claim 2, wherein each lamp energizing circuit is-connected with a lamp, at least two lamps connected with the first energizing circuit set are located on opposite sides of a vehicle, and at least. two lamps connected with the second energizing circuit set are located on opposite sides of the vehicle, whereby when only the first set of lamp env ergizing circuits are biased continuously into activation, at least one lamp on each side of the vehicle is continuously lighted, while at least one lamp on each side of the vehicle flashesl

Claims

1. A multiple lamp energizing circuit having three lamp energizing modes and including: a. a first set of at least 2 lamp energizing circuits, b. a second set of at least 2 lamp energizing circuits, c. each of said lamp energizing circuits including control means responsive to an electrical input signal for activating the energizing circuit and each having first and second control connections, d. a means for producing two alternating out-of-phase outputs at first and second output terminals, e. a selector switch including 1. a bias connection, 2. a first switch output, 3. a second switch output, and 4. means for selectively connecting the bias connection with one of the first output, the second output, and neither output, f. a unidirectional current conductor means in addition to and distinct from the control means of the energizing circuits and conductive in one direction between first and second connections, g. said first output terminal of said alternating producing means being connected to the first control connection in at least one and less than all energizing circuit control means of said first and second sets of energizing circuits, h. said second output terminal of said alternating output producing means being connected to the first control connection of the remaining energizing circuit control means of both sets of energizing circuits, i. the second control connection of all of the first set of energizing circuits being connected to the first connection of the unidirectional conductor means and to said first switch output, j. the second control connection of all of the second set of energizing circuits being connected to the second connection of the unidirectional conductor means and to the second switch output, whereby in operation, (1) with the selector switch bias applied to neither switch output, said alternating output means activates energizing circuits of both sets that are connected with the first input terminal of the alternating output producing means, alternately and out of phase with the remaining energizing circuits of both sets that are connected with the second output terminal of the alternating output producing means, (2) with the switch bias connection connected to the first switch output, an overriding bias is applied to the second control connections of all of the circuits in the first set and blocked by the unidirectional conductor means from the circuits of the second set, to continuously activate only the circuits of the first set while the second set continues to be alternately activated outof-phase, and (3) with the bias connection connected to the second switch output, the overriding bias is applied to the second control connections of all of the second set of circuits and, via the unidirectional conductor means, to the second control connections of the first set to cause all circuits continuously to be activated.

2. a first switch output,

2. The lamp energizing circuit according to claim 1 wherein the means for producing first and second out-of-phase electrical output signals is a continuously running astable multivibrator.

3. The lamp energizing circuit according to claim 1, wherein energizing circuits from each of the two lamp energizing circuit sets controlled by the two out-of-phase outputs are connected with lamps on the opposite sides of a vehicle to cause a distracting out-of-phase flashing.

3. a second switch output, and

4. The lamp energizing circuit according to claim 2, wherein each lamp energizing circuit is connected with a lamp, at least two lamps connected with the first energizing circuit set are located on opposite sides of a vehicle, and at least two lamps connected with the second energizing circuit set are located on opposite sides of the vehicle, whereby when only the first set of lamp energizing circuits are biased continuously into activation, at least one lamp on each side of the vehicle is continuously lighted, while at least one lamp on each side of the veHicle flashes.

4. means for selectively connecting the bias connection with one of the first output, the second output, and neither output, f. a unidirectional current conductor means in addition to and distinct from the control means of the energizing circuits and conductive in one direction between first and second connections, g. said first output terminal of said alternating producing means being connected to the first control connection in at least one and less than all energizing circuit control means of said first and second sets of energizing circuits, h. said second output terminal of said alternating output producing means being connected to the first control connection of the remaining energizing circuit control means of both sets of energizing circuits, i. the second control connection of all of the first set of energizing circuits being connected to the first connection of the unidirectional conductor means and to said first switch output, j. the second control connection of all of the second set of energizing circuits being connected to the second connection of the unidirectional conductor means and to the second switch output, whereby in operation, (1) with the selector switch bias applied to neither switch output, said alternating output means activates energizing circuits of both sets that are connected with the first input terminal of the alternating output producing means, alternately and out of phase with the remaining energizing circuits of both sets that are connected with the second output terminal of the alternating output producing means, (2) with the switch bias connection connected to the first switch output, an overriding bias is applied to the second control connections of all of the circuits in the first set and blocked by the unidirectional conductor means from the circuits of the second set, to continuously activate only the circuits of the first set while the second set continues to be alternately activated out-of-phase, and (3) with the bias connection connected to the second switch output, the overriding bias is applied to the second control connections of all of the second set of circuits and, via the unidirectional conductor means, to the second control connections of the first set to cause all circuits continuously to be activated.