US 3813664 A
Apparatus for supervising equipment wherein plural signal paths are provided respectively developing signals indicative of errors in parts of the equipment, having a plurality of warning lights each including several light emitting gallium-arsenide diodes, a transistor for controlling the diodes, a filter and a translucent plate in front of the diode. The warning lights are turned in response to the signals, a logic-or-configuration receives these signals and turns on, a multivibrator which drives a main warning light, also including light emitting diodes, transistor, filter and translucent plate.
Description (OCR text may contain errors)
United States Patent Geyer May 28, 1974 APPARATUS FOR SUPERVISING 2,934,752 4/1960 Arrasmith 340/2131 EQUIPMENT WITH WARNING LIGHTS 3,228,026 1/1966 Coronado-Arce 340/380 X 3,412,392 11/1968 Jenkins 01 al. 340/248 C  Inventor: Wo f G y Klrchweyhe, Germany 3,452,347 6/1969 Stimson 340/249 3 492 488 1/1970 Goettelmann .1 302/311 X  Assigneez Yereinlgte Flugtechnlsche Werke Fok er Gesenscha mit I 3,660,674 5/1972 Bolinger 340/331 X geschrankter Haftmg Breman Primary Examiner-John W. Caldwell ermany Assistant Examiner-Daniel Myer  Filed: May 24, 1972 Attorney, Agent, or FirmRalf H, Siegemund  Appl, No.: 256,314  ABSTRACT Apparatus for supervising equipment wherein plural 1 1 Foreign pp y Data signal paths are provided respectively developing sig- May 29, 1971 Germany 2126905 nals indicative of errors in parts of the equipment,
having a plurality of warning lights each including sev-  US. Cl 340/248 R, 307/31 1, 340/252 R, eral light emitting gallium-arsenide diodes, a transistor 340/378 for controlling the diodes, a filter and a translucent  Int. Cl. G08b 21/00 plate in front of the diode. The warning lights are  Field of Search 340/248, 252, 253, 213.1, turned in response to the signals, a logic-or- 340/380, 331, 378; 307/311 configuration receives these signals and turns on, a multivibrator which drives a main warning light, also  References Cited including light emitting diodes, transistor, filter and UNITED STATES PATENTS translucent plate 2,144,138 1/1939 Batcheller 340/252 17 Claims, 3 Drawing Figures f SI-l 70 ,1 H r """1 62' 5 g as :44 a 1 I M T M 1 a 1-, ,1
1 1, i "4 i i =5 l '1 I 4 4/ a PNE I i c Tunnmn" '1 4 i MN I 1 l5) 1 1 32; AW 1 I v'vvv A 5 1 E i 1 a? l 1 I A l g V II" 1 "WA i g i l 5 J l 1! 1 w 29 I 27 E a 1, i 1 )3 l 1 1 1 2 1 l 1 l l 26 1 H5 ms g L J PATENTED 1m 28 I974 SHEET 1 UF 2 I5 LED APPARATUS FOR SUPERVISING EQUIPMENT WITH WARNING LIGHTS BACKGROUND OF THE INVENTION The present invention relates to apparatus for supervising and/or testing equipment and includes indication lights which light up as steady light or blinks, whenever the equipment or a particular portion thereof no longer works properly.
Utilization of such control lamps and in the indicating manner, is known, and it is also known to combine such lamps in a suitable panel. However, the known arrangements of this type are not useable in all cases, as, for example, a lit-up lamp may develop heat which by itself may become an undesirable source for operating disturbances. This fact is particularly disadvantageous when the panel is mounted in and forms part of the cockpit in an aircraft. It has been observed that the cockpit may develop thermal conditions which come up to or even exceed the permissible limits, independently from the operation of the supervising or test equipment itself. Therefor, it is necessary to provide for accelerated heat removal in these cases, which is an additional expenditure, and aside from the cost factor, it adds to the weight of the aircraft. Weight increase is basically undesirable so that usually additional heat removal is not provided for. That, in turn, is detrimental as to the certainty of the equipment.
DESCRIPTION OF THE INVENTION It is an object of the present invention to avoid the difficulties above and to provide for apparatus for supervising and/or testing of equipment, constructed so that heat developed during operation can be neglected. In accordance with the preferred embodiment of the invention, it is suggested to use plural gallium arsenide diodes as indicator lights and to be operated in direction of easy conduction. The diodes are arranged behind translucent plates, each defining an illumination field in such a manner that the point like source of light as established by the diode is converted into a uniformly lit panel.
The heat developed by such an illumination is so low in comparison with the usual incandescent lamps, so that the resulting thermal conditions are not of any detriment to the operation of the equipment in general.
In cases, several such diodes are used, and it is of advantage here to connect them electrically in parallel. Moreover, a color filter is to be placed behind the illumination field defining plate. The filter has passage range about equal to the spectrum line width of the light emitted by the diode. It was found that the field is better illuminated in this manner. The diode pertaining to an illuminating unit should be structurally com bined with a transistor to establish an illumination module. The diodes are the load resistors for the transistor, connected, for example. in the collector circuit thereof. The module includes two resistors alternatingly connected to the emitter circuit ofthe transistor for brightdim control. The base electrode of that transistor includes a Zener diode and a resistor in voltage divider configuration.
The module construction as outlined above permits reduction in occupied space and weight for the entire apparatus as constructed from many of such modules. Moreover, the transistor control as suggested limits the current through the light emitting diodes. Plural indicator light modules are connected to be respectively turned on in response to one of a plurality of possible error indicating signals. A main warning light responds, preferably with a delay, to any one error indicating signal, whereby preferably the transistor-diode configuration of the main warning light constitutes a resistance component of an astable multivibrator, turned on in case of error and providing blinking control.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:
FIG. 1 is an exploded view of an illumination unit in accordance with the preferred embodiment of the invention;
FIG. la shows a modification ofa detail in FIG. I and FIG. 2 is a circuit diagram for the control of an alarm equipment with multiple warning lights.
DESCRIPTION OF THE DRAWINGS Proceeding now to the detailed description of the drawings, FIG. 1 illustrates an illuminating control device in push-button construction. A push-button switch 10 has a mount 11 for receiving a socket 12. A plug-in unit 13 is mounted on socket l2, and a miniature printed circuit board 14 is placed into the unit 13. Three light emitting diodes 15 of the gallium arsenide variety are disposed on the upper side of board 14. A board 14' is illustrated as alternative unit with a single diode 15. The underside of the board may carry the electronic circuitry for this particular warning and indicator light module.
The p.c. board when placed into container 13 is covered by a filter plate 16 onto which is placed a translucent disk 17. A cap 18 may be provided to maintain the assembly in position in container unit 13. The three diodes 15 illuminate the translucent disk 17 from the back, and the disk 17 establishes a uniformly lit illumination field as seen from above. The particular diodes emit red light; the filter 16, thus, has a passage or transmission range that covers the 650 nanometer wavelength over sufficient bandwidth. Filter cut-off should match complementarily the bandwidth of the emitted light.
Assuming the arrangement when assembled is used as a main warning light, the push-button 10 may be used to close a switch which is closed upon pushing the button. The switch may be used to extinguish the warning light, and, possibly, to initiate other operations related to the warning condition.
Turning now to FIG. 2, illustrating parts of a control circuit for warning indicators in an airplane. The warning device may include plural warning or alerting lights 20 and a main warning light 21. Each alerting light 20, as well as main warning lamp 21, includes three light emitting diodes 15, provided in a module 23 (denoted 23' for the main light). The modules 23 and 23 each include a transistor 22 having its collector circuit established by'parallel circuit connection of the three diodes 15. Two resistors 24 and 25 are connected directly to the emitter of transistor 22. One or the other of these resistors is connected to a source of negative voltage potential. The resulting change in bias permits brightdim control of the respective illumination as resulting from light emission by the diodes.
Completing the description of each module, the base electrode of the transistor 22 is connected to the junction between a resistor 27 and a Zener diode 26. Elements 26 27 are serially connected across the source of operating voltage and bias the base of the respective transistor 22 in voltage divider configuration. Particularly, the cathde of the Zener diode connects to the said base electrode. This way, the transistor provides current limiting control for the light emitting diodes 15.
A relay 28 is associated with each module 23 and having a normally open contact 29, positive biasing voltage potential is supplied to the module 23 only when the relay is closed. The relays have their energizing circuit connected to one side of the positive biasing voltage; the other side is under control of the condition that may lead to the need for warning.
The equipment to be supervised has plural monitoring lines M, leading out of the equipment and being effective for error indication, for example, through internal closing ofa switch applying negative driving voltage potential as an error indicating signal to the particular error monitoring line that leads out of the equipment. In the present example, such lines are presumed, each leading to the energizing circuit of one out of the ten error indicator relays 28.
Thus far, the modules are the same for alerting lights as well as for the main warning light. However, module 23' constitutes also a load resistance network for a transistor 31 which pertains to an astable multivibrator 30. Aside from transistor 31, multivibrator includes another transistor, and they are cross-coupled in the usual manner. Positive voltage potential is applied to the multivibrator whenever a normally open contact 36 of a relay closes. Relay 35 pertains to a delay and timing circuit 40 which is connected for operation to a switch. Particularly, switch 50 includes a transistor 51 and the circuit 40 as a whole connects to the collector of this transistor 51.
The delay circuit 40 includes a uniq'unction transistor 41 whose gate is under control of an RC-circuit, that begins to run when switching transistor 51 is rendered conductive. The delay is given by the period that elapses from turn-on of transistor 51 to the point in time the RC-circuit reaches the firing potential oftransistor 41. The uni-junction transistor 41 controls a thyristor which, when fired. applies directly the switching signal from transistor 5! to relay 35, whereupon the relay responds and closes its contact 36. Whenever transistor 51 is rendered nonconductive, the thyristor in unit 40 extinguishes and relay 35 opens.
Switch 50 is operated in response to a disturbance in the system to be supervised. For this each of' the It) error monitor lines M connects via a resistor 60 and a diode 61 to switch 50. The ten diodes 61 together form a logic-OR circuit. Thus. switch 50 can be turned on by any one or several of the disturbance signals in monitor lines M.
Each diode 61 with series resistor 60 pertains to a gate circuit 65. The gate is constructed to be normally open, for which condition a thyristor63 in the gate circuit is nonconductive. Thus, each gate permits normally the disturbance signal to pass to the particular OR-gate input for turning switch 50 on. All gates 65 can be disabled when respective thyristors 63 are tired. Such bias causes also the relays 28 to de-energize.
Two push-button switches and 71 are provided for turning off the main warning light 21. The switches 70 and 71 are connected in parallel and are respectively associated with the seats for pilot and co-pilot. One contact of each switch connects to the source of positive voltage potential, the other side connects to the anodes of several diodes 62, for control of the thyristors 63 to which they are connected. Thus, upon closing either switch, 70 or 71, all gates 65 are closed, and no disturbance signal can reach switch 50. The switch turns off accordingly, opening relay 35. One of the switches may be incorporated as switch 10 (FIG. 1) in the main warning light.
It will be recalled that each module 23 has a pair of emitter resistors 24 and 25. The one end of all resistors 24 are interconnected to a common terminal 750, and the one end of all resistors 25 are interconnected to a common terminal 75b. A switch 75 is connected to the source of negative voltage potential and operates to provide alternatingly that potential to terminal 75a or 75!). Accordingly, the lights which are turned on otherwise, shine either brightly or dimly. A separate brightdim switch 76 provides the same function for resistors 24 and 25 in module 23. Switches 75 and 76 are mcchanically or otherwise interconnected. They are sepa rately provided so as to insure independency of opera tion of the main warning light.
In operation, under normal operating conditions, none of the relays 28 is energized. Therefor. all mod ules 23 have their light emitting diodes 25 biased to dark. Switch 50 is off, multivibrator 30 is inoperative and main warning light 21 is likewise off.
As a disturbance is detected pursuant to the supervision, the one particular relay 28 is energized, its contact 29 closes and applies operating voltage to the associated module 23; the alerting light of the latter lights up. Switch 75 has particular position, so that, for example, during the daytime, the emitter is biased for higher current in the transistor and the light emitted by the diodes is bright; during nighttime, dim light suffices.
The particular disturbance signal is also applied to the respectively associated gate circuit 65 via the input resistor 60 thereof. The diode 61, being one input element of this OR-configuration as defined, passes the signal to switch 50 which turns on the delay circuit 40. After the time of circuit 40 has run, relay 35 responds and closes contact. The multivibrator 30 begins to oscillate and the main warning light 21 begins to blink accordingly. The alerting light particularizes the disturbance and aids in the localization thereof. The alerting lights may be provided with suitable labelling for this purpose.
The delayed turn-on of the main warning light makes sure that surges and temporary disturbances do not instigate a main warning condition. The RC-circuit in delay circuit 40 stops charging as soon as switch 50 is turned off (transistor 51 nonconductive). The charge will bleed-off through leakage shortly thereafter. The construction of the time element 40 under utilization of a unijunction transsistors, permits very accurate time metering here, so that the definition of temporary is subject to accurate determination.
After the main alarm has been noticed, one or the other switch, 70 or 71, can be pressed. The positive signal as applied to all anodes of diodes 62 serves as disabling signal in that the respective thyristor in gating circuit 65 fires, blocking and disabling diode 61. As the energizing path to switching circuit 50 is interrupted, energizing potential is removed from the time member 40, particularly from the thyristor thereof, so that relay 35 is de-energized. Contact 36 opens and the multivibrator stops. As main warning light 21 receives its operating voltage through the multivibrator, it is turned off.
The circuit shown in FIG. 2 is designed to supervise and/or test ten pieces of equipment. That number is selected solely for illustrative purposes and the actual number depends on the equipment to be supervised. The circuit does not offer any difficulties concerning operating temperature as the losses in the circuit generally and in the light emitting diodes in particular are quite low. It is also important, and bears directly on low loss conditions, that the disturbance monitor and primary control circuit is galvanically separated from and decoupled from the indicator and warning circuit.
Generally, it is deemed advisable to use a stabilized voltage supply. This is particularly so for airplanes as other voltage sources used in airplanes are actually permitted to exhibit wide variations in accordance with present day regulations.
The changeover from bright to-dim is particularly advantageous as ambient light conditions vary greatly, particularly as between day and night. The bright indication may be needed when the outside light is very bright. while dim light is preferred during the night.
The relays 28 and others are preferably constructed as micro-reed relays to limit the space per module and indicator circuit. These relays have a long life so that the life of the equipment as a whole and the period of expected faultless performance are very high. Also, since the apparatus is very insensitive to temperature variations, it is very suitable for ground tests of airplanes which quite often last for hours.
The invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departures from the spirit and scope of theinvention are intended to be included.
1. Apparatus for supervising equipment wherein plural signal paths are provided, respectively developing signals indicative of errors in parts of the equipment, comprising:
a plurality of warning lights each including at least one light emitting diode, a transistor for controlling the diode and a translucent plate in front of the diode;
first circuit means connected for respectively controlling the warning lights in response to the signals; second circuit means including a logic-orconfiguration connected for providing a control signal when one of the signals indicative of error is developed;
a main warning light also including a light emitting diode, a transistor for controlling the diode and a translucent plate in front of the diode; and
switching means responsive to the control signal and connected to the transistor-diode configuration of the main warning light, to turn the main warning light on in response to the control signal.
2. Apparatus as in claim 1, each warning light including plural such diodes connected in parallel and being driven by the respective transistor.
3. Apparatus as in claim 1, the diode connected to the collector of the transistor, and including plural alternatingly effective resistors in the emitter circuit of the transistor for obtaining bright-dim control of the light emitted by the diode.
4. Apparatus as in claim 1, the switching means in cluding an astable multivibrator, the diode-transistor configuration of the main warning light constituting resistance means in and forming part of the multivibrator. and circuit means effective to turn the multivibrator on in response to said control signal.
5. Apparatus as in claim 4, the circuit means including a resettable delay circuit for rendering the signal effective with a delay as to turning the multivibrator on.
6. Apparatus as in claim 1, the switching means including a micro-reed relay for applying operating voltage to the diode-transistor circuit of the main warning light in response to said signal.
7. Apparatus as in claim 1, wherein the diodes are gallium-arsenide diodes.
8. Apparatus as in claim 1, the switching means including a resettable delay circuit for developing the control signal only when one of the signals indicative of error persists beyond a particular period.
9. Apparatus as in claim 1, wherein the switching means includes particular means for obtaining an onoff control of the main warning light.
10. Apparatus as in claim 9, wherein the particular circuit means is an astable multivibrator, the diodetransistor circuit of the main warning light being included in the multivibrator.
11. Apparatus as in claim 1, the second circuit means including gating means for inhibiting the OR- configuration in response to an external command.
12. Apparatus as in claim 1, the first circuit means including plural relays respectively responsive to the error indicating signals and, when closed, providing supply voltage respectively to the warning lights.
13. Apparatus as in claim 1, the transistor of a warning light of the plurality having the respective diode connected to its collector circuit and having a selectible emitter circuit for bright-dim control of the warning light.
14. Apparatus as in claim 1, wherein each light has plural diodes connected electrically in parallel and being disposed side-by-side.
15. Apparatus as in claim 1, wherein each light includes a filter having transmission range only in the emission range of the diode.
16. Apparatus as in claim 1, wherein the first circuit means includes a relay for applying collector bias to the transistor through the diode as load and in response to the signal.
17. In an apparatus for indicating, supervising or testing equipment developing a signal indicative of error, the improvement comprising:
at least one light emitting gallium-arsenide diode; a
translucent plate mounted in front of the diode for establishing a uniformly distributed illumination from the plate;
a transistor connected to the diode for current conduction through the diode in forward direction;
8 in voltage divider configuration for biasing the transistor to conduction; and circuit means responsive to the signal for providing voltage supply to the multivibrator thereby supplying voltage to the diode-transistor circuit.