US 3207948 A
Description (OCR text may contain errors)
Sept. 21, 1965 R. F. BEGUIN LIGHT CONTROLLED SIGNAL SYSTEM 5 Cmw i wm e 3 +1 05N wfi 3 M 12 L e W M urL 1 w? 4 Z Filed March 8, 1963 United States Patent 3,207,948 LIGHT CONTROLLED SIGNAL SYSTEM Richard F. Beguin, Evanston, 11]., assignor, by mesne assignments, to Fidelitone, Inc., Chicago, 111., a corporation of Illinois Filed Mar. 8, 1963, Ser. No. 263,884 2 Claims. (Cl. 315-459) This invention relates to a light controlled signal system and more particularly to a light controlled assembly for use in railroad work. Signal lamps for use on railroad track switches and cross-overs have been used for many years. Such signal lamps may be tied in with track switching mechanism or track control system for showing a clear track or a stop. Such signal lamps have generally been kerosene lamps wherein four lenses or bulls eyes facing in four directions have been provided. Such lamps burn continuously on one filling of kerosene for about a week. Thereafter, the wick must be trimmed, the lenses cleaned and a charge of kerosene must be provided. This upkeep is quite costly.
By contrast, a signal lamp operated from a primary battery can, under proper conditions, energize a signal lamp for longer periods of time and requires battery replacement only, thus reducing the cost of upkeep. This invention provides an electrically energized lamp system which can be used as a replacement of an entire kerosene burner assembly, with the kerosene tank part being used as a housing. In accordance with the present invention, means are provided for energizing the signal lamp only during the time when there is little or no daylight. The lamp when thus energized may in one form of the invention be on continuously or, in another form of the invention, may flash intermittently.
A system embodying the present invention is efficient from an electrical point of view in reducing current drain to a minimum. Furthermore, during the time that the signal lamp is energized, the new system permits most of the power used by the entire system to be fed to the signal lamp, with minimum power used in the control system. The invention provides for eflicient operation of the control system and quick transition from On to OE of the signal lamp.
A further feature of the system embodying the present invention resides in the mechanical structure of the assembly. This mechanical structure makes it impossible to dispose the assembly incorrectly in the holder. This is quite important, since incorrect disposition of the components of the system may interfere with the full passage of light from the signal lamp through the lenses or bulls eyes of the housing. In addition, the physical layout of the system embodying the present invention makes it impossible for faulty operation due to obstructions in the light path between the lenses on the one hand and the signal lamp bulb on the other hand, and also between the lenses on the one hand and the light responsive element on the other hand.
In general, the physical layout of the parts is such that not only is the entire assembly positioned in the lamp housing properly with respect to the bulls eyes, but no part of the assembly is likely to cast any shadows in the bulls eye when the signal lamp is lit.
For a fuller understanding of the invention, reference will now be made to the drawings wherein:
FIGURE 1 is an elevation of a lamp embodying the invention, one part being broken away.
FIGURE 2 is a section on broken line 2-2 of FIG- URE 3.
FIGURE 3 is a section on line 33 of FIGURE 1.
Referring first to FIGURE 4, indicates a photo-electric cell of the type adapted to generate a potential. Such 3,207,948 Patented Sept. 21, 1965 cells are used in photo-meters for photography and the like. Cell 10 has cathode 11 connected to base 12b of PNP transistor 12. Transistor 12 has emitter 12e connected by wire 13 to junction point 14 on wire 15 going to anode 16 of cell 10.
Wire 15 has junction point 18 connected by wire 19 to base 201) of NPN transistor 20, emitter 20a of this transistor being connected by wire 21 to junction point 22 on wire 23 which is connected to collector of transistor 12.
From junction point 18, a connection including bias resistor 25 is provided to junction point 26 which is connected to the positive terminal of an energizing battery. Junction point 26 is connected to emitter 28a of PNP transistor 28 whose base 28b is connected through bias resistor 30 back to junction point 26 and thus to emitter 28e. Base 28b of transistor 28 is also connected through coupling resistor 33 to collector electrode 200 of transistor 28. Base 20b of transistor 20 is connected by wire 35 through capacitor 36 and dropping resistor 37 through junction point 38 to collector electrode 280 of transistor 28. Junction point 38 is connected to one terminal of incandescent lamp 40, the other terminal of which is connected to wire 23 which is connected to the negative terminal of the energizing battery.
The circuit described and including capacitor 36 is adapted to flash the incandescent lamp intermittently, providing photo-electric cell 10 is not exposed to light. Without capacitor 36, the lamp will be energized continuously rather than flashed, under the same conditions.
Assuming that the resistors are of proper value, and assuming capacitor 36 is shorted out, the system works as follows. As long as cell 10 has no light thereon to generate a potential, emitter 12e will be biased positively to base 12b and transistor 12 will be non-conductive. While transistor 12 does not conduct, the potential of its collector and emitter electrodes will not be impressed upon the emitter and base electrodes of NPN transistor 20 and transistor 20 conducts. When cell 10 first has light from outside cut off (as when night falls) transistor 12 becomes non-conductive and transistor 28 starts to conduct. The relative electrode potentials of transistor 20 are impressed upon PNP transistor 28 and causes normally non conducting transistor 28 to become slightly conductive. The changing electrode potentials at transistor 28 reacts upon transistor 20 and its electrodes so that one reacts upon the other transistor to effect a quick change of the two transistors from non-conducting to conducting. As soon as transistor 28 conducts fully, current through incandescent bulb 40 will flow and the bulb will be energized.
Transistor 2% draws little current, since the current must go through resistor 37 which is normally quite high in value. If flashing is desired, capacitor 33 is in circuit as shown. When lamp 40 is on, the drop between junctions 38 and 26 causes capacitor 36 to charge. When capacitor 36 is charged, transistor 20 cuts oil and this cuts transistor 28 01f. As soon as both transistors cut off, capacitor 36 discharges. Then transistors 20* and 28 assume their normal conducting condition in the manner set forth when cell 10 first initiates the operation. When this occurs, current will flow through capacitor 36 to charge the same and during this time, incandescent bulb 40 will be energized. When lamp 40 is on, most of the IR drop between point 26 and wire 23 is across the lamp. This provides high efiiciency.
When light is falling upon cell 10, a potential is generated by the cell and the base of transistor 12 is no longer negative to the emitter and causes transistor 12 to conduct. This in turn causes transistor 20 to begin to cut off and this reacts upon transistor 28 and vice versa. The switching action initiated by cell results in very fast action by the transistors. In addition, the flashing action due to capacitor 36 results in fast switching of lamp 40. In all cases, when lamp 40 is being extinguished, whether by the action of cell 10 or capacitor 36, the reduction in current through the lamp is fast.
As examples, the components making up a system without capacitor 36 can have the following values.
Cell 10 is a silicon solar cell SS22LC sold by Solar System, Inc. Transistsor 12 is a GT2823. Transistor is a GT1938, and transistor 28 is a GT2823.
Resistor has a value of 22,000 ohms; resistor 30 has a value of 330 ohms; resistor 33 has a value of 330 ohms; and resistor 37 has a value of 27,000 ohms. A 6- volt battery is used for energizing the system and the bulb is a type 1867 bulb of General Electric Company.
If flashing of bulb 40 is desired, then capacitor 36 is used, and, in an example, this can be a 20 microfarad capacitor. Resistor 37 will be 3300 ohms, while resistor will be 100,000 ohms. Resistor 30 will be 1800 ohms. Everything else will be the same.
The entire system has the advantage of not relying upon resistors in high megohm ranges. Such high resistors cause considerable ditficulty due to the possibility of moisture or dirt forming a conducting or high resistance film between parts and impairing the operation of the system. All the components are disposed in metal can 50, which is attached to bracket 51 of canister 52. Canister 52 has a battery in the interior thereof and access to the battery may be obtained by opening canister top 54 to expose the battery.
Bracket 51 is a strip of metal having top portion 56 on which can 50 is supported by spring clips 57. Bracket 51 has side arms 58 and 59 which extend toward canister top 54 and welded thereto. Supported from top portion 56 is lamp socket 61 carrying lamp 40. Lamp extends straight down and the axis of the lamp and socket is substantially midway between arms 58 and 59. Canister top 52 carries bracket 63 upon which is supported 'photo-cell housing 64 having the cell proper 10 and window 65 through which light can reach cell 10. Cell housing 64 is positioned below lamp 40 and offset along the direction of portion 56 of bracket 51. Cell window 65 is directed at to the length of portion 56 and parallel to the plane of cover 52. Bracket 51 is narrow enough so that window 65 and lamp 40 will have a light path in the direction faced by window 65. The entire assembly of light and cell carried by cover 52 fits inside of housing cover 68 of square shape as viewed in plan. Thus cover 68 has four side walls carrying four lenses or bulls-eyes 69 to 72 inclusive. These may be of glass or plastic, of suitable colors and supported in conventional fashion. The diameter of each lens and the elevation is such that when housing top 68 is positioned over lamp base 74, light from bulb 40 can go through all lenses in four directions. Cell window 64 is below lamp 40 but can receive suflicient light through lens 69 to be controlled by light external to the entire lamp housing. Lens 69 has its surfaces so arranged that at night when lamp 40 is lit, there will be little or no light from lamp 40 to affect cell 10, as the result of reflection. Furthermore, cell housing 64 is close enough to lamp 40 so no shadow of housing 64 will appear in the beam from lens 69 due to light originating with lamp 40.
The entire lantern can be handled by grip 76. Lamp base 74 may fit or be shaped to be attached to any suit- 4 able support. Base 74 is simply part of the old kerosene lamp which is modernized by the present invention.
The length of portion 56 of assembly bracket 51 is such that the assembly and lamp housing 68 can be put together only as illustrated in FIGURE 2, where bracket portion 56 is diagonally disposed in housing 68.
Resistor 25 and capacitor 36 control the flash repetition rate. Capacitor 36 and resistor 37 determine the On time. Resistor 33 limits the current and is determined by the transistor characteristics. Resistor 30 holds transistor 28 at cut-oflf and prevents excessive leakage at warm temperatures. In cold weather, this resistor can be left out. Resistor 30 and lamp 40 will both affect the timing.
What is claimed is:
1. A lamp system for use where a lamp must be flashed intermittently under conditions of darkness and cut off under conditions of daylight, said system comprising a photo-electric cell having a cathode and an anode and adapted to generate a potential under the influence of light, a first transistor of the PNP type having a base, collector and emitter electrode respectively, means for connecting the cathode to said base, means for connecting the anode to said emitter, a second transistor of the NPN type, a direct connection between the emitter of the first transistor and the base of the second transistor, a direct connection between the collector of the first transistor and the emitter of the second transistor, a first, resistor disposed between the base of said second transistor and the emitter of a third PNP transistor, a second resistor disposed between the collector of the second transistor and the base of the third transistor, a third resistor connected across the base and emitter of the third transistor, an incandescent lamp connected between the collector of the third transistor and the emitter of the second transistor, and a circuit between the base of the second transistor and the collector of the third transistor, said last named circuit including a fourth resistor, said system be ing adapted to have a battery whose positive terminal is connected to the emitter of the third transistor and whose negative terminal is connected to the emitter of the second trnasistor, the value of said first resistor being greater than the second resistor, said second and third resistors having generally values of the same order, said fourth resistor having a value which is between that of the first resistor and the values of the second and third resistors, said system being adapted to switch said light on or olf quickly as the result of action on the photo-cell, the second and third transistors cooperating with each other to effect a quick change in the conductive or nonconductive conditions, both of said transistors being substantially conductive or non-conductive simultaneously.
2. The system according to claim 1 wherein said last named circuit has a capacitor connected between the collector of the third transistor and the base of the second transistor, said capacitor being in series with the fourth resistor and functioning to cause said signal lamp to flash intermittently when the photo-cell is dark.
References Cited by the Examiner UNITED STATES PATENTS 2,973,456 2/61 Smyth 3l5l59 3,093,744 6/ 63 Tabet 250-239 3,128,412 4/64 Abromaitis 315159 JOHN W. HUCKERT, Primary Examiner. ARTHUR GAUSS, Examiner.