US3604949A - Monitoring circuits for direct current circuits - Google Patents

Monitoring circuits for direct current circuits Download PDF

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Publication number
US3604949A
US3604949A US47516A US3604949DA US3604949A US 3604949 A US3604949 A US 3604949A US 47516 A US47516 A US 47516A US 3604949D A US3604949D A US 3604949DA US 3604949 A US3604949 A US 3604949A
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US
United States
Prior art keywords
transistor
voltage
resistance
monitoring circuit
transistors
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Expired - Lifetime
Application number
US47516A
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English (en)
Inventor
Gerhard Conzelmann
Adolf Kugelmann
Heinz Moller
Heinz Kammerer
Karl-Ernst Boeters
Hans-Joachim Fleischer
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication date
Priority claimed from DE19691930753 external-priority patent/DE1930753C/de
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q11/00—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00
    • B60Q11/005—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00 for lighting devices, e.g. indicating if lamps are burning or not
    • B60Q11/007—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00 for lighting devices, e.g. indicating if lamps are burning or not the lighting devices indicating change of drive direction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
    • B60Q11/00—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00
    • B60Q11/005—Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00 for lighting devices, e.g. indicating if lamps are burning or not

Definitions

  • Striker ABSTRACT The voltage drop across a control resistor in the monitored direct current circuit, which drop varies in accordance with the condition of the direct current load, affects CIRCUITS the amount of current throu h g a differential amplifier and 20 Claims 5 Drawing causes operation of a transistor switch in one of the two col- [52] U.S.Cl 307/235, lector circuits of the amplifier whenever the load current 315/77, 340/80, 340/251 changes sufficiently. The switch controls an indicating device.
  • the invention relates to the circuitry for monitoringdirect current circuits, particularly in lamp circuits of turn signals on motor vehicles.
  • the monitoring is effected by a potential drop that varies in dependence on the current drawn by the lamps. The potential drop customarily occurs across a control resistor.
  • the arrangements of the prior art usually use a current relay in the lamp circuit, the relay permitting the lamp to blink only when all lamps are burning.
  • the relay so acts on the blinker unit that the blink frequency is noticeably raised when a lamp fails. This rise in frequency serves as the monitoring system signal that tells that the turn indicator is not operating properly.
  • control resistances of low value can be used.
  • the blinker unit and its monitoring arrangement must operate reliably over a wide range of temperatures and operating voltages.
  • the manufacturing tolerances for the electric incandescent lamps and the components of the circuit must be taken into account, as must the fact that in European motor vehicles the negative pole of the battery is connected as a rule to the vehicle frame, so that the control resistor must be connected in the positive line of the lamp circuit.
  • An object of the invention is to provide a monitoring circuit for direct current circuits, particularly for blinker units, such as those of turn signals on motor vehicles, and which monitoring circuit avoids the disadvantages outlined above, particularly the disadvantage of having to adjust the monitoring circuit.
  • Another object of the invention is a circuit of the preceding object and constructed as a monolithic integrated circuit.
  • the invention consists fundamentally of a monitored circuit having a load that draws current in dependence on its condition, and two voltage points between which there exists a potential drop that varies in dependence on the current drawn by the load; and a monitoring circuit for producing a signal whenever the load current indicates a predetermined condition of the load, the monitoring circuit including a reference voltage, a differential amplifier having a plurality of transistors, including first and second transistors, a common.
  • resistance means for the emitters of the first and second transistors and biasing means, such as for biasing each base of the first and second transistors so that the latter conduct, at least one each of first and second diodes connected with regard to polarities during operation so as to conduct current between the base of a respective one of the first and second transistors and a respective one of the two voltage points, whereby a change in voltage at one of these voltage points atfects the collector current in both of the first and second transistors, means connecting the collector of one of the first and second transistors to that one of the two voltage points which is at the greater potential difference with respect to the reference voltage, and signal generator means including control switch means, which latter are connected between the collector of the other of the first and second transistors and the one voltage point for operation whenever the collector current of the other transistor changes sufficiently in response to a sufficient change in the current through the load.
  • Fig. l is a circuit diagram showing the invention in its fundamental form
  • FIG. 2 is a modification of the circuit shown in FIG. 1;
  • FIG. 3 shows a circuit that can be adjusted for a voltage-dependent load resistance
  • FIG. 4 shows the modified part of the circuit of FIG. 3, for obtaining the desired voltage dependence of the switching range
  • FIG. 5 is another embodiment of the invention that is particularly well adapted to manufacture with monolithic integrated circuit techniques.
  • the positive line 10 contains a (PNP resistance 12 and leads to a load, which is shown as a resistance 11, but in one practical application of the invention can be the filaments of the turn signal lamps.
  • the one end of the load resistance is connected to the minus line 13, which in a motor vehicle is grounded as a rule. This line serves as the reference potential. If opposite types of transistors were employed PNP for NPN and NPN for PNP) then. of course, the polarities of the two lines 10 and 13 would be reversed, but line 13 would still serve as the reference potential.
  • the two voltage points, or ends, A and B of the control resistance 12 are connected to respective diodes l4 and 15, that are also connected by their cathodes to the respective bases of transistors 16 and 17. Since proper polarities are observed, the diodes conduct; and the respective transistor bases are approximately at the voltages at A and B.
  • the transistors 16 and 17 and their common emitter resistance 18 constitute a differential amplifier.
  • a respective resistance 19 and 20 which set the quiescent current through the diodes l4 and 15.
  • the amplified signal is taken off the collector of transistor 22 and conducted to some visual or audible indicating device, such as a signal lamp, to enable monitoring of the turn signals circuit.
  • the transistor 22 together with the indicating device constitute a signal generating means.
  • the monitoring circuit just described operates in the following way.
  • the collector currents of the transistors 16 and 17 are equal.
  • the value of the resistance 21 is such that the potential drop across it is sufficient to bias the transistor 22 to conduct. If current begins to pass through the load 11, voltage point B falls with respect to voltage point A, the collector current of transistor 17 declines, and the potential drop across resistance 21 reduces until the transistor 22, which acts as a switch means, is cut off.
  • This circuit operates satisfactorily provided that the temperature stability and operation over a wide range of voltages are not required. If there is required a high degree of temperature stability, together with a switching range that is independent of the operating voltage, then the circuit of FIG. 2 is particularly advantageous.
  • a resistance 23 in series with a diode 14 shift the switching range of the transistor 22 to the region where the collector currents of the transistors 16 and 17 are equal. Switching occurs when the ratio of resistance 19 to resistance 23 is approximately equal to the ratio of the resistance of load 11 when conducting current to the control resistance 12.
  • the differential amplifier is fed from a constant current source, which comprises a transistor 24 having as emitter resistance 29 in the common emitter circuit of the transistors 16 and 17. The base of the transistor 24 is connected to the resistance 20 and through the pair of series connected diodes 2S and 26 to the minus line 13.
  • the temperature stability is particularly good if the characteristics of one of these diodes are at least similar to those of the emitter diode of transistor 24 and the characteristics of the other diode are at least similar to those of the emitter diode of transistor 22. Particularly favorable results are obtained if these diodes consist of the emitter diodes of transistors that are of the same type as the respective transistors 22 and 24.
  • the temperature stability of the circuit is further improved if the combined resistance of the parallel connection of the resistance 21 and the direct current input resistance of the transistor 22 is approximately twice the value of the resistance 29. By suitably choosing the working point, the value of the direct current input resistance of the transistor 22 is made advantageously large with respect to the resistance 21.
  • the switching range of the monitoring circuit of FIG. 2 is very largely independent of changes in operating voltage and temperature, it may be necessary, when the load 11 has a voltage-current curve of the general class to which that of a tungsten electric filament belongs, to shift the switching range slightly to accommodate the voltage-dependent resistance of the load 11.
  • this kind of voltage-dependent shift is obtained by stabilizing the operating voltage for the differential amplifier and the transistor switch 22.
  • the operating voltage lies between voltage points A and C.
  • the stabilization is ensured by a zener diode 27 connected through a resistance 28 to the minus line 13.
  • the degree of shift can be varied by means of a resistance 30 connected between the line 13 and the base of transistor 16. It may be advantageous, particularly if the circuit is manufactured as a monolithic integrated chip, not to connect the resistance 30 directly to the base but instead to a variable tap on the resistance 19.
  • FIG. 4 shows another embodiment for adjusting the switching range to the voltage-dependent resistance of the load 11, when the latter, for example, is a turn signal lamp.
  • a resistance 31 is connected in series with the zener diode 27.
  • the voltage at point C is furnished by a current amplifier consisting of a PNP transistor 32 and NPN transistor 33, an expedient that greatly reduces the power loss in this branch.
  • the collector of transistor 22 is connected to the base of a transistor 34, which accomplishes the actual switching.
  • a resistance 35, shunted across the base-emitter path of transistor 34, ensures a particularly narrow switching range of only a few millivolts.
  • the circuit of FIG. 5 operates in the following manner. Assuming that the load 11 consists of two parallel-connected incandescent electric lamps, the voltage drop across resistance 12 is greater than across resistance 23. The collector current of transistor 17 is therefore smaller than that of transistor 16, and the transistors 22 and 34 are cut off. But if only one lamp flashes, then the voltage drop across resistance 12 is smaller than across resistance 23, the current through transistor 17 is greater than through transistor 16, and both transistors 22 and 34 conduct, causing a signal to be operated. If the signal is to be operated when the transistor 34 is cut off, then transistor 22 and the resistance 21, together with transistor 34 and resistance 35, are connected into the collector circuit of transistor 16.
  • the series-connected resistance 23 and diode l4 explained in description of the embodiment of FIG. 2, can also be used in the embodiment of FIG. 1.
  • the additional features, described in connection with the embodiments of FIGS. 3, 4 and 5, can also be incorporated into the simple circuit of FIG. 1.
  • the monitoring circuit of the invention is constructed as a monolithic integrated circuit, components that mutually affect the electrical performance of each other if their temperatures change are advantageously located, in so far as possible, on isotherms of the semiconductor chip. Numbered among these components are, for example, the transistors 16 and 17; the diode pair 14 and 15; the transistor 24 with the diode 25; the diode 26 and the transistor 22; the resistances 19, 20 and 23; or 28 and 31; or 29 and 21.
  • the diodes 25 and 26 it has been assumed that the characteristics of the former correspond to those of the emitter diode of transistor 24, and those of the latter to the characteristics of the emitter diode of transistor 22.
  • the circuit (the monitored circuit) for the turn signals is constructed on a monolithic crystal, or chip, the monitoring circuit of the invention is advantageously incorporated on the same chip.
  • a monitored circuit having load means that draws current in dependence on its condition, and two voltage points between which there exists a potential drop that varies in dependence on the current drawn by said load means; and a monitoring circuit for producing a signal whenever the load current indicates a predetermined condition of said load, said monitoring circuit including a reference potential; a differential amplifier having a plurality of transistors, including first and second transistors, common resistance means for the emitters of said first and second transistors, and biasing means for biasing each base of said first and second transistors so that the latter conduct; at least one each of first and second diodes connected with regard to polarities during operation so as to conduct current between the base of a respective one of said first and second transistors and a respective one of said two voltage points, whereby a change in voltage at one of said voltage points affects the collector current in both of said first and second transistors; means connecting the collector of one of said first and second transistors to that one of said two voltage points which is at the greater potential difference with respect to said reference potential
  • biasing means are first resistance means connected in the base of said one transistor and second resistance means connected in the base of said other transistor.
  • a monitoring circuit as defined in claim 2 including a constant current source connected in the emitters of said first and second transistors.
  • said constant current source includes at least one third transistor of which the collector is connected to the emitters of said first and second transistors; at least one diode conductively connecting the base of said third transistor to a voltage of correct polarity so that said third transistor is biased to conduct; and wherein said common resistance means are connected between said voltage of correct polarity and the emitter of said third transistor.
  • a monitoring circuit as defined in claim 8 including a control resistance means connected in said monitored circuit and across which said potential drop occurs, and wherein the desired switching range of said switch means occurs where the resistance ratio of said third resistance means to said first resistance means is approximately equal to that of said control resistance means to said load means under current.
  • said switch means comprise a transistor and third resistance means for biasing and connected between the base and the emitter of the transistor of said switch means, the latter transistor being complementary to said other transistor and connected between the collector of the latter and said one voltage point so that is conductive state depends on the amount of the collector current of said other transistor and so that its direct current input resistance occurs between its base and emitter; and
  • the resistance resulting from the parallel connection between said third resistance means and the direct current input resistance of the transistor of said switch means has approximately twice the value of said common resistance means.
  • a monitoring circuit as defined in claim 16 including a current amplifier connected to furnish said intermediate voltage.
  • monitoring circuit as defined in claim 1, wherein said monitoring circuit is a monolithic integrated circuit and mutually affecting temperature sensitive components thereof are placed along at least approximate isotherms of the semiconductor crystal so as to reduce temperature differences between these components.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Lighting Device Outwards From Vehicle And Optical Signal (AREA)
  • Alarm Systems (AREA)
  • Measurement Of Current Or Voltage (AREA)
US47516A 1969-06-18 1970-06-18 Monitoring circuits for direct current circuits Expired - Lifetime US3604949A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691930753 DE1930753C (de) 1969-06-18 Schaltanordnung zur Überwachung von Gleichstromkreisen

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US3604949A true US3604949A (en) 1971-09-14

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US47516A Expired - Lifetime US3604949A (en) 1969-06-18 1970-06-18 Monitoring circuits for direct current circuits

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US (1) US3604949A (ja)
JP (1) JPS5228468Y1 (ja)
AT (1) AT306544B (ja)
FR (1) FR2040973A5 (ja)
GB (1) GB1314246A (ja)
NL (1) NL7008858A (ja)
SE (1) SE356264B (ja)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3719937A (en) * 1971-02-11 1973-03-06 Master Specialties Co Failure detection circuit
US3747062A (en) * 1971-01-13 1973-07-17 Lucas Industries Ltd Direction indicating systems for road vehicles
US3955174A (en) * 1972-04-20 1976-05-04 C.A.V. Limited Direction indicator system for road vehicles with trailer adapter means
US3988644A (en) * 1975-09-26 1976-10-26 Motorola, Inc. Current protection circuit
FR2392574A2 (fr) * 1977-05-27 1978-12-22 Jaeger Detecteur de defaut de lampe, notamment pour vehicule automobile
US4195281A (en) * 1977-03-21 1980-03-25 Essex Group, Inc. Lamp outage indicator circuit
US4214236A (en) * 1978-10-02 1980-07-22 The Bendix Corporation Driver circuit for an electrical load with capability for detecting a short in the load
US4291302A (en) * 1978-11-13 1981-09-22 King Gordon A Lamp monitoring circuits
US4399429A (en) * 1980-09-23 1983-08-16 Renix Electronique S.A. Electronic adapter for a diagnostic pickup of data supplied by an electronic control circuit
US4641045A (en) * 1984-11-13 1987-02-03 American Standard Inc. Fail-safe one and only one signal checking circuit
US5057814A (en) * 1989-07-24 1991-10-15 Harley-Davidson, Inc. Electrical malfunction detection system
US6759851B2 (en) 2002-07-02 2004-07-06 Delphi Technologies, Inc. Method and apparatus for control and fault detection of an electric load circuit
US20040145838A1 (en) * 2003-01-28 2004-07-29 Hazelton Lawrence Dean Method and apparatus for control and fault detection of a remote electrical motor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1436112A (en) * 1972-04-20 1976-05-19 Cav Ltd Direction indicator system for road vehicles

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3103617A (en) * 1958-05-06 1963-09-10 Burroughs Corp Voltage regulation with temperature compensation
US3428943A (en) * 1966-01-10 1969-02-18 Bendix Corp Automobile turn signal with lamp failure indicator

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3103617A (en) * 1958-05-06 1963-09-10 Burroughs Corp Voltage regulation with temperature compensation
US3428943A (en) * 1966-01-10 1969-02-18 Bendix Corp Automobile turn signal with lamp failure indicator

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3747062A (en) * 1971-01-13 1973-07-17 Lucas Industries Ltd Direction indicating systems for road vehicles
US3719937A (en) * 1971-02-11 1973-03-06 Master Specialties Co Failure detection circuit
US3955174A (en) * 1972-04-20 1976-05-04 C.A.V. Limited Direction indicator system for road vehicles with trailer adapter means
US3988644A (en) * 1975-09-26 1976-10-26 Motorola, Inc. Current protection circuit
US4195281A (en) * 1977-03-21 1980-03-25 Essex Group, Inc. Lamp outage indicator circuit
FR2392574A2 (fr) * 1977-05-27 1978-12-22 Jaeger Detecteur de defaut de lampe, notamment pour vehicule automobile
US4214236A (en) * 1978-10-02 1980-07-22 The Bendix Corporation Driver circuit for an electrical load with capability for detecting a short in the load
US4291302A (en) * 1978-11-13 1981-09-22 King Gordon A Lamp monitoring circuits
US4399429A (en) * 1980-09-23 1983-08-16 Renix Electronique S.A. Electronic adapter for a diagnostic pickup of data supplied by an electronic control circuit
US4641045A (en) * 1984-11-13 1987-02-03 American Standard Inc. Fail-safe one and only one signal checking circuit
US5057814A (en) * 1989-07-24 1991-10-15 Harley-Davidson, Inc. Electrical malfunction detection system
US6759851B2 (en) 2002-07-02 2004-07-06 Delphi Technologies, Inc. Method and apparatus for control and fault detection of an electric load circuit
US20040145838A1 (en) * 2003-01-28 2004-07-29 Hazelton Lawrence Dean Method and apparatus for control and fault detection of a remote electrical motor
US6960918B2 (en) 2003-01-28 2005-11-01 Delphi Technologies, Inc. Method and apparatus for control and fault detection of a remote electrical motor

Also Published As

Publication number Publication date
GB1314246A (en) 1973-04-18
SE356264B (ja) 1973-05-21
AT306544B (de) 1973-04-10
FR2040973A5 (ja) 1971-01-22
NL7008858A (ja) 1970-12-22
DE1930753B2 (de) 1972-01-27
JPS5228468Y1 (ja) 1977-06-28
DE1930753A1 (de) 1971-01-14

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