US3329868A

US3329868A - Blinking light control arrangement

Info

Publication number: US3329868A
Application number: US311545A
Authority: US
Inventors: Domann Helmut; Moller Heinz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1962-09-29
Filing date: 1963-09-25
Publication date: 1967-07-04
Anticipated expiration: 1984-07-04
Also published as: DE1191722C2; GB1048478A; DE1191722B

Description

July 4, 1967 H- DOMANN ETAL BLINKING LIGHT CONTROL ARRANGEMENT Filed Sept. 25, 1963 2 23 Z8 2 73 i, X 5 ,46 I3 w 3' 4 i F a a 3,329,858 Patented July 4, 1967 4. fire 3,329,868 BLINKING LIGHT CONTROL ARRANGEMENT Helmet Domann and Heinz Miiller, Stuttgart, Germany, assignors to Robert Bosch G.m.b.H., Stuttgart, Germany Filed Sept. 25, 1963, Ser. No. 311,545 Claims priority, applicatigg (gzrmany, Sept. 29, 1962,

9 12 Claims. (Cl. 315225) The present invention concerns a blinking light control arrangement, particularly for motor vehicle signal lights, where by operation of a switch selectively one or another group of signal lamps is caused to issue blinking signals while imultaneously a tell-tale lamp is caused to indicate to the operator that the signal lamps issue blinking light signals.

It is one object of the invention to provide for an arrangement wherein the blinking light control comprises a multivibrator which controls the switching operation for the signal lamps at a frequency which increases noticea'bly if in any one of the groups of signal lamps which are switched on one lamp breaks down.

It is another object of this invention to provide for an arrangement as set forth above in which the multivibrator is capable of operating only when the operating circuit of one of the groups of signal lamps is rendered operative by actuation of the group selector switch.

It is another object of the invention to provide for arrangements as set forth above which are comparatively very simple in structure and entirely reliable in operation.

With the above objects in view the invention includes a blinking light control arrangement, particularly for motor vehicle signal lights, comprising, in combination, a source of electric energy; work circuit means connected with said source and comprising lamp means, first normally open switch means movable to closed position for rendering said circuit means operative, and electrically controllable normally non-conductive second switch means intermittently changeable to conductive condition; a stable multivibrator means connected with said source and including first and second transistor means in pushpull connection, one thereof being controllingly connected with, said second switch means for intermittently changing the latter between non-conductive and conductive condition; first control resistor means connected between one terminal of said source and said multivibrator means for increasing the frequency of the multivibrator action in response to a decrease of the current flowing through said first control resistor means; second control resistor means connected in said work circuit means for producing at one of its terminals a potential depending upon the current passing through said lamp means when said first and second switch means are in conductive condition; and third transistor means having an output connected with said first control resistor means and having an input connected with said terminal of said second control resistor means, said third transistor means feeding through said first control resistor means a current varying with a variation of said potential at said input, so that when said current flow through said lamp means decrease below a predetermined value and said potential is correspondingly varied, the frequency of the multivibrator action is increased.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing, in which:

FIG. 1 is a schematic circuit diagram of one embodiment of the invention including a multivibrator controlling an electromagnetic relay;

FIG. 2 is a similar schematic circuit diagram illustrating a second embodiment of the invention including a multivibrator controlling a controlled transistor acting as a switch; and

FIG. 3 is a schematic circuit diagram illustrating a modification of the arrangement according to FIG. 2.

The illustrated embodiments refer particularly to an arrangement in a motor vehicle wherein two

groups

10 and 11 of the direction signal lights are provided, each group comprising a pair of signal lamps, the particular group of signal lights to be operated being selectable Iby actuation of a normally open selector switch 14 which is in circuit with a tell-tale lamp 12, a storage battery 16 and a main switch 15 which is usually coupled with the ignition switch of the vehicle. In order to understand the operation of the arrangements described further below it is to be noted that if the battery 16 furnishes 6 volts the resistance of each of the signal lamps would be about 2 ohms and thus the total resistance of each

group

10 or 11 would be 1 ohm. In contrast therewith the resistance of the tell-tale lamp 12 is many times larger, namely of the order of 22 ohms.

Referring now to FIG. 1, it can 'be seen that the circuit arrangement comprises a work circuit connected with the battery 16 and main switch 15 and comprising at least one of the

lamp groups

10 or 11, the selector switch 14 and another normally non-conductive switch including a movable contact member 13' and a stationary contact 13" cooperating with each other and actuated by a relay coil 13. The relay coil 13 is connected for intermittent energization with an astable multivibrator of basically known design but supplemented by components in accordance with the invention. The multivibrator circuit includes a first transistor T and a second transistor T coupled with each other crosswise by means of

capacitors

35 and 36, respectively. The output of the transistor T is connected by line 29 with the coil 24 of the relay 13 for energizing the latter whenever the transistor T is in conductive condition. The multivibrator circuit is connected with the battery 16 by

lines

18 and 23. A third transistor T is provided which serves two purposes, namely first to prevent operation of the multivibrator unless the switch 14 is in one of its conductive positions, and second, for causing a noticeable increase of the operational frequency of the multivibrator whenever one of the two signal lamps forming part of a

group

10 or 11 thereof which has been switched on by the switch 14 should break down and be in non-operative condition.

When the main switch 15 is closed, the line 18 starting at the stationary contact 17 of switch 15 applies positive potential to the emitters of the three transistors T T and T The movable arm of the selector switch 14 is connected by line 19 with the stationary contact 13" of the relay 13 the movable contact 13' whereof is connected via a control resistor 20 with the positive line 18 and simultaneously via a resistor 21 with the base of the transistor T For reasons explained further below the resistance of the resistor 20 is very small and in the present example amounts to only .07 ohm. The tell-tale lamp 12 is connected directly between the

lines

18 and 19. In the described examples all the transistors are of the PNP type. Assuming that the transistor T is a germanium transistor, it has to be taken into consideration that this type of a transistor is greatly dependent on operating temperature. Therefore in this case a temperature-dependent resistor 22 is connected between line 18 and a junction point between the resistor 21 and the base of the transistor T so that in this manner the reactions of this transistor to temperature changes are compensated.

The negative line 23 is taken from the negative terminal of the battery 16 to one terminal of the relay coil 24 and to the four

resistors

25, 2s, 27, 2d. The second terminal of the relay coil 2 is connected via line 29 with the collector of the transistor T while the other end of the control resistor 25 is connected by a line fit) with the collector of the third transistor T The other end of the resistor 26 is connected by a line 31 with the base of the first transistor T the other end of the resistor 27 is connected by a line 32 with the base of the second transistor T and the other end of the resistor 28 is connected by line 33 with the collector of the first transistor T A resistor 34 of comparatively high ohmic value is connected between the lines 29 and 3t) and constitutes together with the above-mentioned control resistor 25 a voltage divider the junction point between the

resistors

25 and 34 being connected with the collector of the transistor T In the usual manner a capacitor 35 is connected between the

lines

36 and 31 and a second capacitor 36- is connected between the

lines

32 and 33. It is advisable to connect a diode 24' in parallel with the relay coil 24. If it is not necessary to obtain a steep rise of the current flowing through the transistor T when the latter is rendered conductive, the above-mentioned resistor 34 can be omitted.

The arrangement according to FIG. 1 operates as follows:

When the main switch is closed but switch 14 is in non-conductive position then both transistors T and T are conductive while the third transistor T is non-conductive. Consequently, the capacitor 35 is now charged and the capacitor 3% is almost discharged. Due to the conductivity of the transistor T the relay coil 24 is energized and therefore the

relay contacts

13 and 13" moved into mutual engagement.

If now while the main switch 15 is still in closed position the selector switch 14 is moved from its idle position into either one of its operative positions, e.g. into that shown in dotted lines so as to close the circuit for the lamp group it}, then current flows from the positive terminal of the battery 16 through the resistor 26 and switches 13, 13 and T4 to the signal lamps 1t) and back to the negative terminal of the battery 16. Consequently the lamps of the group 10 furnish a light signal while the telltale lamp 12 remains dark because substantially the same potential exists at both its terminals. In view of the voltage drop developing across the control resistor 2% the transistor T becomes conductive and operation of the multivibrator is started. In a well known manner the transistors T and T operate in push-pull fashion. Assuming that at a given moment transistor T is conductive and transistor T is non-conductive, then the capacitor 36 is fully charged while, on the other hand, current still fiows through the relay coil 24 and line 23 back to the negative terminal of the battery 16. However the capacitor 35 discharges across the resistor 26. After sufficient discharge the potential at the base of the transistor T becomes negative relative to its emitter and consequently the transistor T becomesconductive. Now the capacitor 36 is charged and the potential at the base of the transistor T is rendered more positive. Consequently the transistor T is rendered nonconductive and the capacitor 35 discharges across resistor 27. No current flows through the relay coil 24 any more so that its relay contact 13' disengages from the stationary contact 13" under the action of the return means not shown, so that the circuit for lamp group 10 which was selected by the setting of the switch 14 is interrupted. The lamps 10 go out but the tell-tale lamp 12 now radiates light because, in view of the above indicated relation between the resistances of lamp 12, on one hand, and lamps it on the other hand, the voltage drop is distributed accordingly between these different types of lamps.

As the capacitor 36 discharges the potential at the base of the transistor T becomes negative relative to its emitter. Consequently the transistor T becomes conductive and the capacitor 36 is charged again. The potential at the base of the transistor T becomes now positive whereby the transistor T is rendered non-conductive. At the same time again current flows from transistor T through the relay coil 24 so that the relay 13 is energized and the

contact members

13 and 13 are brought into engagement. Hereby the operating circuit for the lamp group It is again closed because the selector switch 14 is still in its corresponding position. The lamps of the group It radiate light while now again the tell-tale lamp 12 goes out because it is shunted by the parallel circuit through resistor 2th and closed switch 13', 13".

Hereafter the above described cycle repeats as long as, with the main switch 15 in closed position, the selector switch 14 is in one of its circuit closing positions.

As far as the third transistor T is concerned it can be seen that its input i.e. its base is connected with the resistor 20 through which flows the current which operates the lamp group W or 11 whichever is placed in the circuit by actuation of the selector switch 14. The conductivity of the transistor T depends therefore on the voltage drop across the resistor 2t) which depends, in turn, on the amount of said current flowing therethrough. It is therefore clear that the transistor T is rendered conductive and non-conductive alternately at the same rhythm as the intermittent energization of the respective lamp group and consequently in synchronism with the transistor T of the multivibrator.

In case in either one of the

lamp groups

10 and 11 one of the lamps should break down and become inoperative the resistance across the particular lamp group is correspondingly increased and the current flow reduced so that correspondingly the voltage drop across the resistor 20 will not sufiice for rendering the transistor T sutficiently conductive. This reduces the flow of current through transistor T and control resistor 25 and consequently also the voltage drop across the resistor 25. The result is, as can be seen, that the transistor T will be kept non-conductive for a shorter period of time than before and this causes a reduction of the time period during which the respective lamp group or rather the lamp remaining operative therein is energized. On account of the reduction of the non-conductive period of the transistor T the capacitor 36 which determines the dark period of the respective lamp group is charged to a lesser degree so that the non-conductive period of the transistors T is also shortened and consequently also the dark period of the respective lamp or lamp group is shortened.

The shorter duration of the non-conductive periods of the transistors T and T of the multivibrator has the effect that the operating frequency of the multivibrator increases to more than twice its normal value whenever one of the two lamps of the

selected group

10 or 11 breaks down. This fact would in this case be indicated to the operator by a corresponding increased frequency of the blinking of the tell-tale lamp 12.

Since it is also desirable that the multivibrator oscillates after closing the main switch 15 only when the selector switch 14 is moved into one or the other of its circuit closing positions, it is necessary that in the abovementioned voltage divide-r located in the output circuit of the transistor T the resistance of the resistor 34 is very considerably larger than that of the control resistor 25, preferably at least 15 times as large as the resistance of the resistor 25. The result of this is that when the transistor T is rendered non-conductive by the selector switch 14 being in neutral position the voltage drop across the control resistor 24 is very small. Under these circumstances the non-conductive period of the transistor T will not sufiice for permitting a sufiicient charge of the capacitor 36 so that also the non-conductive period of the transistor T decreases to such an extent that both transistors T and T of the multivibrator re main constantly in conductive condition as long as the selector switch 14 is not moved to one of its circuitclosing positions.

The sec-0nd embodiment illustrated by FIG. 2 differs from the above described embodiment mainly in that the electromagnetic relay 13 is replaced by a control transistor T The relay coil 24 of the relay 13 is replaced by a resistor 37. The emitter of the transistor T is not connected as in FIG. 1 with the positive line 18 but instead with the base of the transistor T The collector of the transistor T is connected via line 19 with the selector switch 14 while the emitter of the transistor T is connected directlywith the control resistor 20 and also via an auxiliary resistor 21 with the base of the transistor T The arrangement according to FIG. 2 operates as follows:

When the main switch is closed but selector switch 14 is in its neutral position both transistors T and T are in conductive condition. However, the transistor T must be selected according to its parameters in such a manner that its base-emitter current is suflicient for rendering the transistor T completely conductive. If now the selector switch 14 is moved e.g. into the circuitclosing position indicated by a dotted line so as to cause energization of the lamp group 10, then the transistor T is capable of carrying an emitter-collector current. Consequently the lamps of the group 10 are energized by a flow of current passing through the control resistor and the transistor T is rendered fully conductive by the voltage drop of about .5 volt across the control resistor 20 and correspondingly varying the potential at the base of transistor T Through the conductivity of transistor T 3 the potential of line 30 rises abruptly so as to become equal to that of the positive line 18. This jump of potential is transmitted by the capacitor 35 to the base of the transistor T whereby the latter is rendered non-conductive. Consequently the multivibrator comprising the transistors T and T starts to oscillate. From here on the procedure and ope-ration is identical with that described above in reference to the arrangement according to FIG. 1. a

The modification according to FIG. 3 differs from the embodiment according to FIG. 1 in that the electromagnetic relay 13 is replaced by two transistors T and T At the same time the series connection of the transistors T and T of FIG. 2 is voided. The relay coil 24 is replaced as in the case of FIG. 2 by the resistor 37. However the emitters of both transistors T and T are connected with that terminal of the control resistor 20 which is connected with the base of transistor T The collector of the transistor T is connected with the selector switch 14 while its base is connected via an auxiliary transistor 38 with the collector of the transistor T The base of transistor T is connected with the collector of transistor T and at .the same time with a junction point between the resistor 34 and the additional resistor 37. Finally, the collector of the transistor T is connected via an auxiliary resistor 29 with the negative line 23 of the arrangement. On account of this arrangement the transistor T operates in phase opposition to the transistor T While transistor T operates in phase opposition to the transistor T and therefore in phase with the transistor T Thus, it can be seen that the effect of the circuit according to FIG. 3 is generally the same as that of the embodiments of FIGS. 1 or 2.

It may be added that theoretically the resistor 34 could be dispensed with and a satisfactory operation of the circuit arrangement could be obtained, provided that it is not deemed necessary to provide for a steep rise of the current furnished upon conductivity of transistor T and a steep drop of the current upon change of transistor T to non-conductivity. In this case the capacitor 35 would be connected only directly with the collector of the transistor T which becomes conductive only after the relay 13 has been energized. Consequently, the feedback from transistor T to transistor T will be the more substantial the smaller is the resistance of resistor 34. On the other hand, it is necessary that the resistance ratio within the

voltage divider

25, 34 is as small as possible in order to make sure that the capacitor 34 will be charged to almost the full voltage of the battery 16. Therefore a reasonable compromise between these two desirable conditions is the above-mentioned resistance ratio of 1:15.

It will be understood that each of the elements described above or two or more together, may also find a useful application in other types of blinking light control arrangements particularly for motor vehicle signal lights, differing from the types described above.

While the invention has been illustrated and described as embodied in a blinking light control arrangement particularly for motor vehicle signal lights including an astable multivibrator, it is not intended to be limited to the details shown, since various modifications and structural changes may be made Without departing in any way from the spirit of the present invention.

Without further analysis the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this inventi-on and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed and desired to be secured by Letters Patent is:

1. A flashing light arrangement comprising, in combination, incandescent lamp means adapted to operate in flashing manner; a source of electric current; an electric circuit connecting said source of electric current to said lamp means; interrupter means associated with said electric circuit for interrupting operation of said incandescent lamp means; oscillator means arranged in said circuit for intermittently actuating said interrupter means so that said source of electric current intermittently actuates said lamp means, resulting in flashing thereof; indicator means actuated by current passing through said electric circuit so as to deliver periodic indications at a frequency which corresponds to the frequency of flashing of said incandescent lamp means; means for varying the frequency of oscillation of said oscillator; and actuating means cooperating with said electric circuit for automatically actuating said means for changing the frequency of said oscillator whenever the electric resistance of said lamp means changes.

2. A flashing light arrangement according to claim 1, wherein said oscillator means is an astable multivibrator.

3. A flashing light arrangement according to claim 1, wherein said oscillator means is a transistorized astable multivibrator including two transistors operating in pushpull mode.

4. A flashing light arrangement according to claim 1, wherein said actuating means is a transistor circuit sensitive to variation of electric current through said lamp means.

5. A flashing light arrangement according to claim 1, wherein said actuating means is a transistor circuit sensitive to variations in the current through said lamp means and causing the frequency of said oscillator to increase when the electrical resistance of said lamp means is substantially increased.

6. A flashing light arrangement according to claim 1, wherein said lamp means comprises a first and second lamp arrangement, and switching means connected to said lamp arrangements for selecting one thereof as desired.

7. A flashing light arrangement according to claim 6, wherein said first and second lamp arrangement each has at least one lamp adapted to operate in a flashing manner.

8. A flashing light arrangement according to claim 5, including means for compensating impedance variations in said transistor circuit which are due to thermal consaid source of electric current to connect .on one hand ditions, thus maintaining the impedance in said transistor a disc nnect on t e other hand said source of electrlc circuit substantially constant. Current Wlthln 531d arrangement- 9. A flashing light arrangement according to claim 1,

including relay means arranged in said electric circuit 5 References (mad and operated by said oscillator means, said relay means UNITED STATES PATENTS operating said interrupter means upon being actuated by 2,891,195 6/1959 Smyth 315 20( said oscillator means. 2,972,706 2/1961 Malm 315200 10. A flashing light arrangement according to claim 1, 2,973,456 2/1961 Smyth 315-200 wherein said indicator means is a lamp. 10 3,002,127 9/ 1961 Grontkowski 31S-200 11. A flashing light arrangement according to claim 1, 3,022,467 2/ 1962 Leedcr 315200 wherein said source of electric current is a battery.

12. A flashing light arrangement according to claim 1, JOHN HUCKERT Primary Exammer' including a main operating switch connected in series with 15 D. O. KRAFT, J. SHEWMAKER, Assistant Examiners.

Claims

1. A FLASHING LIGHT ARRANGEMENT COMPRISING, IN COMBINATION, INCANDESCENT LAMP MEANS ADAPTED TO OPERATE IN FLASHING MANNER; A SOURCE OF ELECTRIC CURRENT; AN ELECTRIC CIRCUIT CONNECTING SAID COURCE OF ELECTRIC CURRENT TO SAID LAMP MEANS; INTERRUPTER MEANS ASSOCIATED WITH SAID ELECTRIC CIRCUIT FOR INTERRUPTING OPERATION OF SAID INCANDESCENT LAMP MEANS; OSCILLATOR MEANS ARRANGED IN SAID CIRCUIT FOR INTERMITTENTLY ACTUATING SAID INTERMITTENTLY ACTUTHAT SAID SOURCE OF ELECTRIC CURRENT INTERMITTENTLY ACTUATES SAID LAMP MEANS, RESULTING IN FLASHING THEREOF; INDICTOR MEANSACTUATED BY CURRENT PASSING THROUGH SAID ELECTRIC CIRCUIT SO AS TO DELIVER PERIODIC INDICATIONS AT A FREQUENCY WHICH CORRESPONDS TO THE FREQUENCY OF FLASHING OF SAID INCANDESENT LAMP MEANS; MEANS FOR VARYING THE FREQUENCY OF OSCILLATION OF SAID OSCILLATOR; AND ACTUATING MEANS COOPERATING WITH SAID ELECTRIC CIRCUIT FOR AUTOMATICALLY ACTUATING SAID MEANS FOR CHANGING THE FREQUENCY OF SAID OSCILLATOR WHENEVER THE ELECTRIC RESISTANCE OF SAID LAMP MEANS CHANGES.