US 3789232 A
A flasher switch of the type for flashing automobile lamps is provided with outage indication. In a particular embodiment employing two coils producing opposed magnetic forces in a core the change in rate is obtained by inserting or removing an impedance to produce an appreciable discrete change of flux in the core. Preferably the change of flux is such that the flashing rate is increased above the usual rate.
Description (OCR text may contain errors)
0 United States Patent 11 1 1111 3,789,232 Wareing Jan. 29, 1974 FLASHER SWITCH WITH OUTAGE 3,487,358 12/1969 Ubukata a a1. 340/251 3,618,011 1/1969 Leeder, Jr 340/251 INDICATION 3,636,51 1 1/1972 Sahurai 340/251 Kenneth Wareing, 370 Consession St., Hamilton, Ontario, Canada Filed: Nov. 21, 1972 Appl. No.: 308,626
Related US. Application Data Continuation-impart of Ser. No. 179,300, Sept. 10, 1971, abandoned.
US. Cl. 307/10 L S, 340/251, 340/81 R int. Cl H02g 3/00 Field of Search 340/251, 81 R; 315/83;
307/10 LS, 132 R References Cited UNITED STATES PATENTS 2/1972 Gerlach et a]. 307/10 L S Primary ExaminerHerman J. Hohauser Attorney, Agent, or FirmStanley J. Rogers ABSTRACT A flasher switch of the type for flashing automobile lamps is provided with outage indication. In a particular embodiment employing two coils producing opposed magnetic forces in a core the change in rate is obtained by inserting or removing an impedance to produce an appreciable discrete change of flux in the core. Preferably the change of flux is such that the flashing rate is increased above the usual rate.
6 Claims, 3 Drawing Figures fi'IIIIIIIIl PA TENTED JAN29 1974 mm 1 or 2 INVENTOR. KENNETH WAREING AGENT F LASHER SWITCH WITH OUTAGE INDICATION CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation-in-part of my application Ser. No. 179,300 filed Sept. 10, 1971, now abandoned.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is concerned with improvements in or relating to flasher switches, such as are used in automobiles for flashing the signal lights thereof, and especially to such switches with outage indication, i.e. providing automatically to an observer an indication that one or more of the lamps controlled by the switch is not operating.
2. Review of the Prior Art A number of proposals have been made hitherto for flasher switch devices with outage indication, for example in U.S. Pat. Ser. Nos. 2,743,401; 2,844,814; 3,421,143 and 3,421,157. These devices usually include a current measuring arrangement which measures the maximum current flowing in the lamps being flashed, and which provides a lamp, buzzer or meter signal upon a decrease in current caused by a lamp failure.
There is disclosed and claimed in U.S. Pat. Ser. No. 3,247,402, issued 19th Apr. 1966 to Tridon Manufacturing Ltd. a flasher switch wherein a pair of parallelconnected coils are wound on a core to produce opposed magnetic fields, with a capacitance connected in series with one of the coils. Upon supply of current to the switch the fields of the coils oppose one another until the capacitor is charged whereupon the switch closes and the lamps light. Upon closure of the switch the coils are shorted and the capacitor discharges through its coil, this discharge holding the switch closed for a predetermined on period. The switch then opens and the cycle repeats. The complete disclosure of this prior specification is incorporated herein by reference.
DEFINITION OF THE INVENTION It is an object of the present invention to provide a flasher switch with a new type of outage indication.
It is another object to provide a new flasher switch of the kind in which the flashing rate thereof is relatively constant with varying loads, and in which an outage indication is indicated by an increase in the flashing rate.
In accordance with the present invention there is provided a flasher switch for flashing a load and of the type using a magnetisable core, the switch comprising a pair of switch terminals for the connection to the switch of a DC. power source and constituting the end terminals of at least one current flow path through the switch, a switch operator unit connected in a current flow path between the said terminals and having a flashing rate that is changeable by connecting an impedance in the circuit or disconnecting an impedance from the circuit, and a current detector connected in a current flow path and detecting the maximum current flow in the load flashed by the switch, the detector being operative in response to a predetermined decrease in the load current flow to connect or disconnect the said at least one impedance to change the rate of flashing of the switch.
DESCRIPTION OF THE DRAWINGS Particular preferred embodiments will now be described, by way of example, with reference to the accompanying schematic drawings wherein:
FIG. 1 is a schematic circuit of the first embodiment;
FIG. 2 is a similar circuit of a second embodiment; and
FIG. 3 is a similar circuit of a third embodiment.
Corresponding parts are given the same reference in all figures of the drawing.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, the flasher switch operator unit comprises the elements enclosed within the broken line 10, which represents the case or enclosure for the switch. The switch is provided with two terminals 11 and 12 by which it is connected respectively to a source 13 of DC. power, usually an automobile battery, and to the lamps 14 that are to be flashed by the switch with power supplied from the source. These terminals also constitute the end terminals for various current paths through the switch, as will be described below.
A magnetisable switch core 15 carries two equal parallel wound coils 16 and 17 of relatively high resistance (e.g., about 300600 ohms), the coils being arranged to provide opposing magnetic fields upon energisation. The coil 16 has one end connected to terminal 11, while the other end is connected through a resistor 18 and a reed switch operating coil 19 to the terminal 12. The coil 17 has one end connected to the terminal 11 through a capacitor 20, while the other end is connected to the terminal 12 via a resistor 21, a forwardbiased diode 22 connected in parallel with the resistor 21, and the coil 19. The reed switch 23 has its normally open contacts connected in parallel with the resistor 21 and diode 22, so that closure of the switch will short the resistor and diode. An armature 24 of the switch is moved by the core magnetic field and carries a moving contact 25 that cooperates with a fixed contact 26, the armature normally being urged in the direction to open the contacts 25 and 26 by a spring 27. Either of the coils 16 and 17 can when energized produce a magnetic field that will move the armature 24 to close the contacts 25 and 26.
In normal operation of the device, when all of the lamps to be flashed are operative, so that the current flow through the switch is above a predetermined level, the sequence of events is as follows upon closure of an external switch 28, usually the direction-indicator switch of an automobile.
Current flows through both coils l6 and 17 producing equal and opposite fields which cancel one another, so that the armature 24 is not moved. The current flow through the winding 19 is not sufficient for the contacts of switch 23 to close, but the diode 22 is conductive so that the resistor 21 is effectively shunted thereby and does not affect the charging of the capacitor. As the capacitor 20 becomes charged the field produced by the winding 17 decreases until at some point the field of coil 16 is able to move the armature 24 and close the main contacts 25 and 26, whereupon the lamps 14 light. The armature 24 is now shortcircuiting the coils 16 and 17. The field in coil 16 collapses almost immediately, but that in coil 17 is maintained by the discharge of the capacitor 20 through the coil. During this period the current flow through coil 19 is sufficient to close the switch 23, so that the resistor 21 is shunted and does not affect the discharge of the capacitor. The field of coil 17 maintains the contacts 25 and 26 closed and the lamps therefore remain alight until the capacitor has discharged sufficiently, whereupon the main contacts open and the lights go out. The cycle then repeats.
The period taken for the main contacts to close after the switch 28 is closed constitutes the off part of the switch duty cycle, while the period that they are closed constitutes the on part of the same cycle. The operating requirements for such a switch for vehicle direction indicators are now substantially standardised and typically it should produce about 90 flashes per minute, with the lamps in their lighted condition for about 50 percent of the time. The operating requirements of a switch in accordance with the invention can be adjusted, as will be apparent to those skilled in the art, by suitable choice of the values of the various mechanical and electrical switch components. Such a switch as disclosed in US. Pat. No. 3,247,402 permits ready achievement of a duty cycle of about 50 percent, and the duty cycle is not affected by the value of the current load being flashed.
The coil 19 and switch 23 constitute a current measuring detector that is operative when the current flow falls below a predetermined lower level. Such a lower level most usually will be obtained because one or more of the lamps 14 has burned out and is not drawing current, but it may also result from a general deterioration in the conductivity of the lamps and the associated circuit from aging and corrosion. If upon closing of the contacts 25 and 26 the current flow is below the predetermined level the switch 19 remains open and the resistor 21 is inserted in the circuit so that the capacitor must now discharge through the resistor 21, which abruptly decreases the current through the coil and correspondingly abruptly decreases its magnetic field, so that the contacts open after a much reduced on period, resulting in an abrupt and marked increase in flashing rate e.g., from about 90 per minute to about 150 per minute.
It will be seen therefore that a switch inaccordance with the invention provides a commpletely positive and unmistakable indication of lamp outage without the need for expensive external indicators.
As indicated above, on such prior art devices the flashing frequency is also decreased progressively by the deterioration of the circuit conductivity over a lengthy period of time so that an observer is not generally aware of the change that has taken place. It could happen therefore that a false outage indication was given when in fact all lamps were lighting, or alternatively one lamp had failed but the change in flashing frequency was not noted by an observer accustomed to a slower rate. This effect was sufficient to cause difficulty in design of such switches in order to try to ensure that they did not give such false indications. An abrupt increase in the flashing rate is however a positive and unmistakable indication that will immediately claim the attention of the observer.
In the circuit shown in FIG. 2 the operating coil 19 of the reed switch of the circuit of FIG. 1 is replaced by a small resistance resistor, while the switch 23 and the diode 22 are replaced by a transistor 23.
The resistor 19 and the transistor 23 together constitute a current value detector. Thus, if upon closing of the contacts 25 and 26 the lamp current is sufficiently high, then the voltage drop across the resistor is sufficient to bias the transistor to its conductive state, shortcircuiting the resistor 21 and allowing the capacitor 20 to discharge normally. If the current is not sufficient then the transistor remains non-conductive and the capacitor must discharge through the resistor, increasing the flashing rate as described above.
In a modification of the circuit of FIG. 1 shown in FIG. 3 the resistor 21 is replaced by an impedance constituted by an additional winding provided on the core 15. The polarity of this additional winding is such that the flux it produces opposes the flux produced by the windings 17. In operation of this circuit, provided sufficient current passes through the reed switch coil 19 its contacts remain open and the capacitor charges and discharges normally. If the current through the coil 19 decreases sufficiently then the contacts will open; the capacitor charges normally through the diode 22 but discharges through the additional winding which opposes the flux of the winding 17 and causes the contacts to open more rapidly and increase the flashing rate, in additon giving a more positive opening action. It is found that with such a circuit it is possible to approach more closely to the ideal duty cycle of 50% on and 50% off for each lamp.
Although in the specific embodiments described above the change in flashing rate is obtained by inserting an impedance in series with the holding coil 17, the same effect can be obtained instead by changing the impedance of the main coil 16, or by changing the impedance in series or parallel therewith, so as to produce the desired change in the flashing rate.
1. A flasher switch with outage indication comprising, a pair of switch terminals, a magnetisable core, first and second operating coils on the core and connected in parallel between said switch terminals to be supplied in parallel with current from a D.C. power source connected between said switch terminals and to produce in the core upon such supply of current substantially equal opposed magnetic forces, a contactor, biasing means for the contactor, the contactor being movable in one direction from a first to a second position in response to energization of the core by the unopposed magnetic force of one of the operating coils and movable in the opposite direction from the second to the first position under the action of the said biasing means, a capacitor connected in series with the second coil to be charged by current passing through the second coil whereby upon its discharge through the second coil it causes energization of the core sufficient for maintenance of the contactor in the said second position, a
gaged and responsive to a decrease of said current below a predetermined level to connect or disconnect the said flashing-rate changing impedance in circuit to change the switch flashing rate.
2. The invention as claimed i claim 1, wherein the current detector is operative to connect the fiahingrate changing impedance in series with the second coil and capacitor and thereby increase the switch flashing rate.
3. The invention as claimed in claim 2, wherein the rate changing impedance is an inductive coil on the said magnetizable core connecting in series with the said second coil and producing a magnetic force opposing that of the second coil.
4. The invention as claimed in claim 2, wherein the said current detector comprises a magnetically controlled switch having an operating coil in the current flow path including the movable and another contacts and having switch contacts with the said flasing-rate changing impedance connected therebetween, whereby the passage of load current in the operating coil above the predetermined value closes the contacts to shortcircuit the flashing-rate changing impedance, and the passage of load current below the predetermined value does not close the contacts so that the flashing-rate changing impedance is inserted in the circuit in series with the second coil.
5. The invention as claimed in claim 4, wherein the rate changing impedance is an inductive coil on the said magnetizable core connected in series with the said second coil and producing a magnetic force opposing that of the second coil.
6. The invention as claimed in claim 2, wherein the said current detector comprises a load-current receiving impedance in the flow path including the movable and another contacts and a controllable rectifying device having the said flashing-rate changing impedance connected in parallel therewith and controlled by the load-current receiving impedance, whereby the passage of load current in the load current receiving impedance above the predetermined value causes the rectifying device to be maintained conductive and shortcircuit the flashing-rate changing impedance, and the passage of load current below the predetermined value causes the rectifying device to be non-conductive whereby the flashing-rate changing impedance is inserted in the circuit in series with the second coil.
UNITED STATES PATENT OFFICE CERTIFICATE OF CQRRECTION Patent No. 3,789 232' Dated gamma! 22 1214 Inventor(s) Kenneth eing It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Between the lines prefixed by "" and "" insert  Assigneer Tridon Limited, Burlington,
Ontario, Canada Signed and sealed this 9th day of July 1974.
MCCOY M. GIBSON, JR C MARSHALL DAN I N Attestlng Off1cer Commissioner of Patents V UNITED sTATEs PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,789, 232 Datedw Inventor) Kenneth Wareing 7 It is certified that error ap aears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Face Pager Between the lines prefixed by  and  insert  Assigneer Tridon Limited, Burlington,
' Ontario, Canada' Signed and sealed this 9th day of July 1974.
MCCOY GIBSQN, JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents