US 3411036 A
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Description (OCR text may contain errors)
Nov. 12, 1968 C, F, CASEY 3,411,036
WARNING AS SEMBLY Filed June 9, 1966 Car/su F. Can: ey
United States Patent O1 hee 3,411,036 Patented Nov. l2, 1968 3,411,036 WARNING ASSEMBLY Charles F. Casey, Houston, Tex., assignor to Automatic Power, Inc., Houston, Tex. Filed .lune 9, 1966, Ser. No. 556,349 7 Claims. (Cl. 315-149) This invention relates to a warning assembly of the flashing light type useful on offshore structures and the like. In one of its aspects, it relates to such an assembly wherein a standby light flashing system is automatically placed in operation upon failure of a primary or main flashing light system.
Many offshore structures and the like are equipped with flashing warning lights as a navigational aid to inform passing ships of the presence of such structures. Normally, these warning systems are in isolated areas and are unattended. The reliability or integrity of these Warning systems is obviously very important. To aid in this regard, most of them are normally protected against failure due to lamp burn-out by automatic lamp changers. These changers may Iprovide a single standby lamp or a multitude of standby lamps. The lamp changers are reliable for their intended purpose, however, they do not provide protection against lamp-outages due to flasher failure, sun switch failure or system voltage failure. In other words, a system failure may be due to something other than the failure of a lamp and it would be desirable to provide protection against system failure which would include protection against not only lamp failure but also against power supply failure, flasher failure, etc'.
It is therefore an object of this invention to provide a warning light assembly for offshore structures and the like wherein a primary flashing light system is provided with a secondary or standby flashing light system, the arrangement being such that should the primary system stop flashing during a time when it is supposed to be flashing, the second system will be automatically placed in operation.
Another object is to provide such an assembly which is fail safe in that if the primary system stops flashing, even momentarily, the secondary system begins its operation and continues until the primary system is placed back in proper operation.
Other objects, advantages and features of the invention will be apparent to one skilled in the art upon the consideration of the specification, the claims and the attached drawings wherein:
FIG. l is a general illustration f an assembly ernbodying this invention; and
FIG. 2 is a schematic of a preferred relay for actuating the standby light system upon failure of the primary light system.
Referring to FIG. 1, the primary light system is shown as including a power source 10, such as a battery, connected to a light source 11 by a conventional flasher circuit 12, the latter intermittently applying power to the light source or bulb to cause the same to flash. Conveniently, the flasher can control the .bulb so that, for example, it is on 0x3 second and off 0.7 second.
A similar standby light system is also provided and is shown to include a second power source 13, a light source of bulb 14, and a flasher circuit 15. Flasher circuit 15 is adapted, upon actuation, to cause the light source to be intermittently energized to cause the same to flash periodically.
The -second system also includes a lampout relay circuit which is connected to effectively prevent the light source of the second system from being energized until the first system fails and then it automatically causes the second system to be placed in operation. Thus, means are provided which are sensitive to the flashes of light emitted by the first system and this can take the form of a light dependent resistor 16 positioned to view the light emitted by bulb 11. The light dependent resistor is connected to a voltage source 17 (FIG. 2), which could be source 13, and to the base of the transistor 18 via a resistor 19 in such a manner that when the light dependent resistor senses the light from bulb 11, its resistance drops sufficiently to bias transistor 18 to a conducting state. This causes the potential at point 20 to fall to near ground which in turn effectively places point 21 near ground so that the conventional lamp triggering signal generated by the flasher circuit and shown at 22 cannot intermittently bias transistor 23 to fire transistor 24 which controls light bulb 14. Thus it will be seen that when the light dependent resistor 16 is viewing light from bulb 11, an inhibiting voltage is maintained below a predetermined value or, -stated in another way, within a predetermined range, such as to prevent the standby system from being placed in operation. However, since the primary system is intermittently turned off so that the light dependent resistor 16 views light only a part of the time, an RC network is provided which will maintain the inhibiting voltage below a predetermined value within the aforesaid range for a period of time sufficient that the light Isource of the primary system can come back on to again cause transistor 18 to be energized. Thus, a suitable capacitance 25- is connected between the collector and base of transistor 18. This capacitance will charge during the time the light dependent resistor has biased transistor 18 to a conducting state in that current will flow via the light dependent resistor and resistance 19 to the capacitor to point 20 which is at near ground while the transistor 18 is conducting. When the light dependent resistor ceases viewing light, its resistance increases materially thereby removing the bias it has -been supplying to transistor 18 which would then normally become nonconducting. However, since the capacitance 25 has become charged, it will discharge via the base-emitter circuit of transistor 18, power source 17, and loading resistor 26. The RC time constant of the system is made to be such that transistor 18 will be maintained in conducting condition sufficiently long that point 21 will be maintained below the voltage necessary to fire transistor 23 during the dark period and until the light dependent resistor again views light from bulb 11.
In addition to the light from bulb 11, the light dependent 16 `will sense sunlight so that it will act as a sun switch for the secondary or standby light system. Thus it has the dual function of serving both as a sun switch for the second system and also as a means for sensing failure of the rst system. In this connection, it will be noted that the second system will be Iplaced in operation any time the first system fails and this will be true even though the failure of the rst system might be momentary. Thus, should the first system fail for a short period of time, the second system will Ibe placed in operation and upon the first system becoming operative, the second system will be automatically taken out of operation and placed on a standby ibasis.
From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects `hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.
It will be understood that certain features and subcomin the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.
The invention having been described, what is claimed 1. A warning light assembly for otishore structures and the like comprising rst and second flashing light systems each having a power supply, a light source, and means coupling the power supply to the respective light sources and, upon actuation, causing the light sources to be intermittently energized to cause the same to flash periodically; and a control circuit for inhibiting actuation of the second system while the first system is operative including light sensitive means positioned to view flashes of light by the first system, means responsive to said light sensitive means for maintaining an inhibiting voltage within a predetermined range effective to inhibit the second system while said light sensitive means is exposed to light, and means for maintaining said voltage within said range during the time interval the light sensitive means is exposed to darkness between flashes of light from said s first system.
2. A warning light assembly for olshore structures and the like comprising first and second flashing light systems each having a power supply, a light source and means coupling the power supply to the respective light source and, upon actuation, causing the light source to be intermittently energized to cause the same to flash periodically, the second system including an electronic switch connected to eifectively prevent the light source of the second system from being actuated until said switch is actuated; and means responsive to darkness and positioned to receive light emitted `by the light source of the rst system for actuating said electronic switch to energize the second system upon said means being disposed to darkness for a predetermined time.
3. The assembly of claim 2 wherein said sensitive means is positioned to also receive sunlight to prevent said light source of the second system from being energized during daylight hours.
4. The assembly of claim 2 wherein said electronic switch is actuated upon being supplied with a voltage exceeding a predetermined level and wherein said sensitive means includes an element whose resistance is dependent upon the amount of light received thereby and wherein a second electronic switch is connected to said element to cause the second switch to be closed to maintain said voltage below said predetermined level while said element is exposed t-o a predetermined amount of light.
5. The assembly of claim 4 wherein second electronic switch includes an RC network connected to maintain said second electronic switch closed for a time interval after said element ceases to be exposed to light, sufficient to maintain said voltage `below said predetermined level until said element is again exposed to light.
6. The assembly of claim 5 wherein said second electronic switch includes a transistor connected to said first electronic switch to maintain said voltage below said predetermined level while the transistor is conducting, said element being connected to bias said transistor to conduct while said element is exposed to light, a capacitor in the circuit with the transistor to be charged while said element is biasing said transistor to conduct and to discharge through the transistor to maintain it in a conductive state after said element ceases biasing said transistor to a conductive state, for a period of time sucient to maintain said voltage `below said predetermined level until said element again biases said transistor in a conductive state.
7. The apparatus of claim 6 wherein said light sensitive means is positioned to also view sunlight whereby it acts as a sun switch for the second system.
References Cited FOREIGN PATENTS 816,451 7/1959 Great Britain.
JOHN W. HUCKERT, Primary Examiner.
R. F, POLISSACK, Assistant Examiner.