Abstract: Process for monitoring the instantaneous or momentary state of an electric circuit having to function in a range limited to two states, namely a normal state corresponding to the passage of a nominal intensity in a conductor and a critical or threshold state corresponding to a threshold intensity and in particular a zero intensity in the said conductor, using the detection of possible variations in the resistance of a magnetic layer or "magnetoresistor" of the influence of the magnetic field due to the intensity of the electric current circulating in a conductor and whereof part of the path is located in the vicinity of at least one oriented thin magnetic layer, wherein the said detection is carried out by means of a differential measurement of the magnetoresistance of at least two adjacent and separate magnetic layers, whereof one is subject to the field of the circuit to be monitored and the other is subject to the field of a reference current, the circuits and layers being arranged also in such a way as to

Abstract: A recorder of the states of a traffic control system which stores and visually displays the current operational state of the system. The current states of the command signals produced by the traffic controller of the system and the current states of energization of each traffic signal light, after a predetermined delay, are stored in a bistable device. The occurrence of an error, conflicting or improper timing of the energization of the traffic lights of the system or of the command signals controlling the energization of such lights are sensed by a conflict monitor. Upon the occurrence of an error, the bistable devices are latched, i.e. prevented from thereafter changing state. The state of each bistable device is visually displayed as of the occurrence of an error.

Abstract: An improved dual polarity substitution circuit for energizing a secondary load, such as an incandescent lamp, upon failure of a primary load. Dual polarity is achieved through the use of parallel PNP and NPN transistors, one of which conducts so long as the primary load is functional. Upon failure of the primary load and interruption of current flow in the conducting one of the transistors, a bidirectional switch such as a triac is fired to energize the secondary load.

Abstract: A device for indicating when one or more fluorescent lamps in a bank of fluorescent lamps burns out requiring only a single indicator is disclosed. The device includes a voltage divider connected to a terminal of each lamp to produce a signal proportional to the voltage supplied by a ballast to the terminal of the lamp. These signals are then summed at a common summing terminal. The voltage at the summing terminal is approximately equal to the largest voltage of the individual signals produced at each lamp. The signal at the summing terminal is modified, typically through an adjustable voltage divider, to produce a third signalwhich is applied to the gate of an SCR. The adjustable voltage divider is designed so that when any one of the lamps goes out producing a substantial rise in the voltage applied by the ballast to the lamp, the SCR will be triggered. An indicator bulb is connected to the anode of the SCR so that when the SCR triggers, the bulb lights indicating one or more of the lamps are burned out.

Abstract: A signal lamp apparatus with a lamp burnout detecting circuit has a right turn signal lamp group and a left turn signal lamp group which are connected to a power source through a turn signal switch and a relay contact coupled in parallel with a burnout detecting resistor. Each of the lamp groups includes a plurality of signal lamps connected in parallel with one another. The apparatus includes a comparator which produces an output signal when the voltage across the signal lamp group is higher than a predetermined voltage, and a device which produces a burnout signal when the comparator has an output signal after lights-out, for example, after 20 to 100 m sec since the relay contact is opened. With such an arrangement, the burnout of the signal lamp or lamps may be detected while the signal light lamp group is flashing.

Abstract: A control circuit for the turn-signal flasher system of an automotive vehicle. The flasher system includes a relay having switch contacts which are serially connected, together with a direction indicator switch, between the vehicle battery and the turn-signal lamps. A measuring or sampling resistor is connected between the battery and the relay contacts. First and second pulse generators are connected between a first voltage indicator and the relay coil, and are selectively gated to interrupt the relay during normal lamp load conditions. The first pulse generator provides a normal mark-to-space ratio whereas the second pulse generator provides a reduced mark-to-space ratio for use during night driving conditions. Third and fourth pulse generators are responsive to corresponding voltage indicators connected to the measuring resistor. The third and fourth generators function to respectively provide different mark-to-space ratios in response to, and indicative of, lamp outage or current-overload conditions.

Abstract: A lamp failure indicating circuit particularly useful for automotive vehicle application such as detecting failure of headlamps, stop lamps and/or turn signal lamps. The disclosed circuit embodiments monitor branch circuits each containing a lamp load and comprising an associated transformer. Each transformer comprises two coils disposed on a ferromagnetic torroidal core. One coil of each transformer is connected in the branch circuit of the associated lamp load, the coil and lamp load being in series, and being associated with a means which forms therewith a complete circuit path which is independent of the power supply which energizes the lamp load. The other coils of the transformers are connected in a circuit to which a test signal is applied with the result of the test indicating whether any of the lamps are failed.

Abstract: In a device for detecting broken filaments of lamps which are connected with secondary windings of transformers respectively provided for the lamps, primary windings of the transformers being connected in series across an AC power source through a power control device, there are provided a detector for detecting voltage and current delivered from the power control device, and another detector for detecting a phase difference between the voltage and the current thus detected by the voltage and current detector.

Abstract: A circuit is described here for liquid crystal indication systems made up of segments which, using the capacitive performance of the indication system, automatically reveals errors that arise in the segments or due to short-circuits between segments.The invention is adapted for use especially in scales that are to be guaranteed against functional errors.

Abstract: A scale is disclosed which includes a digital display unit for conveying information. A display verification method and system are employed for determining whether a plurality of information conveying segments forming the indicators of the display unit are properly conveying information. Individual segments of the display unit are operated under control of a microprocessor. Segment status determining circuitry determines the operative status of each of the segments by sequentially monitoring a voltage drop indicative of the current passing through an LED comprising that segment. The status determining circuitry produces status information which is stored in the microprocessor memory and compared with data indicative of the information the display should convey if it is properly functioning. If the comparison indicates that one of the segments is not properly conveying the information, warning messages are displayed which indicate maintenance procedures are required.

Abstract: A lamp circuit is provided having a constant current type AC power source and a plurality of isolation transformers connected in series with the AC power source. The secondary circuit of each isolation transformer is connected to an electric lamp. The voltage-time area, which is measured from the rise of the voltage output signal of the power source to the rise of the current output signal of the power source is detected and is compared with a reference predetermined value. Thereby when the detected value exceeds the reference value an alarm signal is generated and the number of the disconnected lamps can be determined and displayed.

Abstract: An electro-optical display device for representation of an item of information such as digits, the display device including a front and rear plate spaced apart to form a cavity for receiving a switchable medium, the front plate on a surface facing the medium being provided with at least one segmented electrode having segments and the rear plate on a surface facing the front plate and the medium being provided with a rear electrode assembly for each segmented electrode, the segments of the segmented electrode and the rear electrode assembly being energized to switch the optical properties in the medium characterized by front control electrodes being disposed on the front plate and electrically connected with selected one of the segments of each segmented electrode and a back control electrode disposed on the rear plate overlying the front control electrode so that an indication is made by one of the front control electrodes and the back control electrodes when the associated segment should be energized.

Abstract: A circuit for monitoring the voltage across a sensing resistor in series with a load, wherein two reference currents are generated, each dependent both on temperature and on the voltage on a power supply line, which voltage is also temperature-dependent and exhibits a temperature coefficient of such a sense and magnitude that the changes in a reference current due directly to changes in temperatures are substantially offset by the changes in that reference current due to changes in the voltage on its power supply line, which changes are in turn due to the same changes in temperature.

Abstract: A flasher apparatus for vehicles capable of protecting from a short-circuit failure. A relay switch is connected in series with an electric power source and direction indicating lamps so that the lamps are energized periodically by the closure of the switch activated by the periodic conduction of an output transistor of an oscillator circuit. A short-circuit detector circuit detects an electric current flowing to the lamps and prevents the output transistor from being rendered conductive in response to the large value of the electric current. The output transistor is allowed to be rendered conductive when a rush current flows to the lamps.

Abstract: An improved apparatus for use in the turn-direction indicating system of a vehicle having directional lamps energized by a battery through a current detecting resistor, a relay and a direction selecting switch. The relay is energized to close periodically in response to periodic pulses produced by a semiconductor integrated control circuit so that the directional lamps flash periodically. A protection circuit which is connected in series with a resistor across the battery render the output transistor of the semiconductor integrated control circuit ON in response to an excessively large positive voltage so that the electric current which flows through the output transistor is limited by the inherent resistance of the relay coil connected in series with the output transistor. A diode which is connected in series with the relay coil render the output transistor ON reversely in response to an excessively large negative voltage so that the electric current is limited by the relay coil.

Abstract: A flasher apparatus for vehicles capable of informing the presence of short-circuit in a direction indicating system and protecting the direction indicating system from burnout. The flasher apparatus receives both a flashing signal for energizing direction indicating lamps and a detection signal indicative of the electric current flowing to said direction indicating lamps. The detection signal is compared with a reference signal so that the short-circuit in the system is detected. Upon detection of the short-circuit, the direction indicating lamps are prevented from being energized to thereby inform the presence of short-circuit and protect the system. The short-circuit detecting operation is disabled for a period of time in which a comparatively large rush current flows to the direction indicating lamps.

Abstract: Apparatus for preventing the simultaneous energization of a pair of traffic lights includes a detection device for monitoring any leakage current in the cables between the traffic lights and a control box. A threshold voltage related to a predetermined level of leakage current to be monitored is coupled to the detection device which actuates an alarm if the leakage current across at least one traffic light exceeds said predetermined level of leakage current.

Abstract: An alternating current lampchanger control circuit for driving a rotatable turret having a plurality of lamps, such as used in a navigational light. An input receives pulsed alternating current signals and is connected to a power circuit including fixed contacts for supplying the pulsed signals to one of the lamps in the turret. A lampout sensing circuit includes a transformer which has a primary in the lamp power circuit and has a rectifier connected to the transformer secondary. Switching means are connected to the rectifier and are actuated to an on position by a lamp failure. An alternating current turret motor is connected to the input or to a continuous source of alternating electrical current through the switching means for rotating the turret upon a lamp failure. The switching means may include a first triac controlling a second triac connected to the motor. Third switching means are included in a feedback loop to provide an alternating current drive for the motor in a continuous mode.

Abstract: A monitoring device for the orderly functioning of lamps, particularly in motor vehicles, with a circuit control element arranged in the circuit of the lamps, on which control element a control signal occurs during switching-on of the lamps, as well as with circuit components in a signal circuit, the latter being applied with the control signal. In the circuit of each lamp there is arranged a low impedance resistor, and the low impedance resistor is connected with an input of an amplifier circuit arrangement. An indicator device is connected to the output of the amplifier.

Abstract: A lamp failure detection arrangement includes a device for interrupting electrical energy to a lamp, and a testing device for generating a low level test signal and for supplying it during the testing interval to the lamp for test purposes without causing the lamp to provide illumination. A device responds to the test signal indicating a failure condition of the lamp for generating a failure condition signal, which can be used both to energize a standby lamp and to generate an attention-attracting signal for alerting an attendant to replace the faulty lamp.

Abstract: A modular panel of dual filament tungsten lamp switches with current limiting, fault indicating, continuous lamp filament testing, and remote control switching capabilities.In one embodiment, the dual filament, self monitoring tungsten lamps are mounted as switches in an array and identified by row and column, the panel including a drum assembly rotatable to a related one of the rows and carrying indicia indicative of the circuits associated with the lamp in each column in the selected row.In a second embodiment, the dual filament, self-monitoring lamps are mounted as switches in an array. Each lamp or the lens cover associated therewith includes circuit identifying indicia visible in daylight by normal contrast and illuminated sufficiently by the lamps for visibility in a dark adapted environment such as the cockpit of an aircraft at night.

Abstract: Plural lamps are connected together at one end and in series with the primary winding of a transformer. The primary winding, responsive to application of an electric potential to one of the lamps, has a potential impressed there across and induces a transient in the secondary winding which generates a back E.M.F. in the secondary winding. A transistorized amplifier connected to the secondary winding amplifies the back E.M.F., and a monostable multi-vibrator has an input connected to the amplifier and is effective, responsive to the amplified back E.M.F., to effect generation of an illumination-received pulse at an output thereof. A J.K.

Abstract: A marker or clearance light for semi trailers and the like which increases the life by a factor of from 3 to 10.

Abstract: A driver circuit for an electrical load device such as an indicator lamp includes the capability to both drive the lamp and to respond to a fault condition in the lamp to disable its energization. The circuit is adapted for control by a single I/O terminal of a programmable logic device. The I/O terminal being of the type having an internal architecture that causes the terminal to be pulled up to a logic high state when unloaded, and pulled down to a logic low state by either external loading or the closure of an internal; program-controlled switch forming part of a low-impedence path to ground. A processor-implemented test routine can be used to monitor the I/O terminal voltage and close the internal switch when the driver circuit responds to a shorted condition.

Abstract: A safety circuit is provided for parallel connected electrical loads. The headlight circuit of an automobile or other vehicle is an important application for the circuit. In the circuit a reversely polled control rectifier is in a parallel conductor subcircuit to the bright lamp filament of the headlight. The gate of the control rectifier is connected to a conductor of the dim lamp filament of the headlight. The control rectifier presents an open circuit when both of the lamps are operable but is adapted to connect the bright lamp filament through a resistor and a diode when the dim lamp filament of the headlight fails.

Abstract: A control apparatus for use in the direction indicating system of a vehicle having a group of front, rear and side directional lamps. The control apparatus includes a capacitor which is charged and discharged alternately and a comparator which reverses the charging and discharging of the capacitor by comparing the voltage across the capacitor with a reference voltage so that the directional lamps flash periodically. The reference voltage is changed from one to another value upon disconnection of the side directional lamp and further changed from one to the other value upon disconnection of the front or rear directional lamp, thus increasing the flashing frequency of the directional lamps upon each disconnection. The capacitor is charged and discharged by respective constant currents to decrease frequency fluctuation at each flashing frequency of the directional lamps.

Abstract: An indicator circuit for indicating whether an incandescent type lamp is burned out. The indicator circuits include a voltage reference source and an indicator LED which is normally biased just below the knee of its conduction curve, but which is biased into conduction whenever the monitored lamp burns out. A bridge circuit is utilized so that relatively small variations in power source voltage do not affect the operating point of the circuit.

Abstract: A display device comprising a plurality of multi-segmented gas discharge display elements each with a common anode and a cathode for each segment in combination with an error detection circuit that signals the failure of one or more segments to ignite.

Abstract: The invention relates to a stop signal monitor circuit for use in conjunction with a vehicle stop lamp system wherein a pair of stop lamps is connectable across the vehicle's electricity supply through a fuse and a respective pair of switch contacts closable in response to the application of vehicle's brake, and wherein a pair of pilot lamps give indication of an open circuit condition existing in either the fuse or one or both of the stop lamps in accordance with the respective operation of the vehicle's brake and the vehicle's ignition switch.

Abstract: A monitoring device for monitoring incandescent lamps, especially in motor vehicles, is provided. A measuring resistor is connected in series with an incandescent lamp to be monitored. Means for monitoring the voltage drop at the measuring resistor are provided. The monitoring means comprises an operational amplifier to one input of which the connection between the measuring resistor and the incandescent lamp is connected and to the other input of which a voltage divider is connected which is mounted in parallel with the measuring resistor and the incandescent lamp. The voltage divider is formed of ohmic resistors, and the output of the operational amplifier controls an indicator means for generating an indication signal upon missing or excessively low voltage drop at the measuring resistor.

Abstract: A system for monitoring the operability of warning lamps which provide a visual signal in the event of the malfunction or unacceptable variation of a monitored function or control comprising a plurality of optical indicators or warning lamps electrically coupled to a single-control switch common to all warning lamps such that all lamps may be simultaneously illuminated upon the closing of the switch to determine their operability.

Abstract: An improved method and apparatus for use in the direction indicating system of a vehicle having a group of front, rear and side directional lamps. The directional lamps are connected in parallel with each other to be energized by a battery through a current detecting resistor, a normally-closed relay and a selection switch. The relay is energized to open periodically in response to a train of pulses so that the directional lamps flash periodically during closure of the selection switch. Closure of the selection switch is detected in response to the voltage across the current detecting resistor to generate the pulses applied to the relay.

Abstract: An error detecting circuit which senses the operating states of a plurality of traffic signal lights the energization of which is controlled by a single block of load switches and which circuit produces an error signal when certain predetermined relations exist for a predetermined period of time between the states of the lights, such as, if more than one traffic signal light of one traffic signal head is energized simultaneously or if none of the traffic signal lights of one traffic signal head is energized.

Abstract: A marker or clearance light for semi trailers and the like which increases the life by a factor of from 3 to 10.

Abstract: A disconnection indicating apparatus for automobiles which electrically detects a disconnection or failure of an automobile turn signal and automatically signals the failure by flashing the disconnected turn signal lamps at an increased flash frequency.

Abstract: A status indicating and current limiting circuit includes a pair of lamp filaments connected in parallel to provide a high reliability for status indication of a monitored switch. The circuit indicates the status of the lamps as well as the open or closed status of the switch. In one embodiment, the pair of lamp filaments are serially connected in parallel between a source of current and the switch so that both the lamp filaments emit bright light when the switch is closed. The lamps are also connected to ground potential through a resistive element to maintain current flow through the lamp filaments when the switch is open, the current being at a level just below the current flow necessary to dimly light the filaments. In the event of a failure of one of the filaments, the other filament will begin to emit a dim but visible light even though the monitored switch is open indicating the failure of the one lamp filament.