US3538379A - Photo-electric light-activated switch apparatus - Google Patents

Description

Nov. 3, 1 70 I l. BERLIN v 3,533,379

PHOTO-ELECTRiC LIGHT-ACTIVATED SWITCH APPARATUS Filed May e, 1968 Fagin": I

Ho-IZOV AC GOCYf INVENTQR. Ina/y 136/ uz United States Patent "ice 3,538,379 PHOTO-ELECTRIC LIGHT-ACTIVATED SWITCH APPARATUS Irving Berlin, 14 Aldo Trail, Trumbull, Conn. 06611 Continuation-impart of application Ser. No. 407,028, Oct. 20, 1964. This application May 6, 1968, Ser. No. 726,803

Int. Cl. H]: 39/ 02; H01h 71/02 US. Cl. 315-159 2 Claims ABSTRACT OF THE DISCLOSURE A light-sensitive lamp control circuit, comprising a Q The present invention relates to photo-electric lightactivated switch apparatus.

This application is a continuation-in-part of my copending application, Ser. No. 407,028 filed Oct. 20, '1964, now abandoned, and'entitled Photo-Electric Light-Activated Switch Apparatus.

, 3,538,379 Patented Nov. 3, 1970 such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

In the drawings:

FIG. 1 is a perspective view of the apparatus according to the invention shown plugged into a receptacle and having a lamp connected thereto;

FIG. 2 is a view showing the components of the aparatus in perspective and diagrammatically showing the conductor wire connections between them;

FIG. 3 is a schematic wiring diagram of the apparatus;

FIG. 4 is a vertical sectional view on an enlarged scale of the combined thermostatic circuit breaker and resistor shown in its circuit closing position; and

FIG. 5 is a similar view showing the same in its circuit opening position; and

FIG. 6 is a part sectional, part elevational view but showing another embodiment of the invention, adapted to a lower range of ambient temperatures.

Referring to the drawings and more particularly to FIG. 2, the components of the photo-electric light-activated switch apparatus, according to the illustrated exemplary embodiment of the invention, comprise a lightsensitive photo-electric cell 10, a thermostatic circuit breaker unit 11, a resistor 12 mounted in direct heat- Heretofore, apparatus of this type has been expensive e series with a photo-electric cell. The photo-electric cell acts as a gate, presenting a high resistance when it is not exposed to light so that very little current flows in the heating circuit. When exposed to light the photo-electric cell presents a low resistance permitting current to flow and causing the resistor in series with the photo electric cell to heat up and through its direct heat-conducting contact with the thermostatic circuit breaker" to actuate the latter. The circuit breaker according to the invention may be either normally open or normally closed so that upon actuation it will either, permit or prevent the flow of current to the load.

7 It is a further object to provide means that can be readily plugged into a conventional 110/120 v. alternating current power outlet or receptacle and to which means lamps, motors, or other appliances using alternating current can be similarly connected.

Another object of the invention is to provide an improved automatic light activated switch apparatus in accordance with the foregoing, wherein the effects of ambienttemperature are minimized, thereby to enable the apparatus to function properly over a wider range of surrounding temperatures.

Other objects and advantages will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawingswherein a satisfactory embodiment of the invention is shown. However, it will be'understood that the invention is not limited to thedetails disclosed but includes all conductive relation upon the circuit breaker, a hermetically sealed container 13 having the photo-electric cell 10 mounted in a wall thereof with its eye exposed and having the thermostatic circuit breaker 11 and the resistor 12 enclosed therein, a combined plug and receptacle unit 14 for plugging into a /120 v. alternating current power outlet or receptacle 15 and for receiving the plug 16 of an appliance to be controlled, for example an electric lamp 17, and a 3-wire cord connection 18 extending between the components carried within the container 13 and the plug and receptacle unit 14.

The thermostatic circuit breaker illustrated by way of example comprises an electrical and heat insulation body 19 having terminals 20 and 21 mounted therein and respectively provided with contacts 22 and 23 normally engaged by a contact bar 24 under the pressure of a leaf spring 25, and adapted to be disengaged therefrom to break the circuit through depression of a plunger 26. Depression of the plunger is brought about through activation of a bimetal disc 27 of concave-convex form mounted in the upper end of the body beneath a closure cap 28 crimped over the body part as at 29.,The closure cap is preferably of aluminum or other suitable metal and the resistor 12 is secured exteriorly thereon in heat.- conductance relation, preferably by an epoxy adhesive 30. Upon heating of the resistor through the flow of current therethrough, heat is conducted directly to the closure cap 28, which through its proximity to the bimetal disc activates it at a predetermined rise in the temperature and deactivates it at a predetermined lowering of the temperature.

The disc 27 receives heat from he cap 28 by direct radiation therefrom, also by convection due to the movement of air confined between the disc and cap, and also by directconduction of heat from the peripheral portions of the cap to the marginal portions of the disc. All three forms of heat transfer are therefore utilized to provide for the maximum effective and efficient transfer of heat from the cap to the disc. I

' In the illustrated example the normal position of the bimetal disc is the one in which its convex side is uppermost, and in this position the circuit breaker is closed; When subject to the predetermined high temperature the disc snaps to the positions as seen in FIG. 5 wherein its curvature is reversed to cause the plunger 26 to be depressed and the contact bar to be moved to open position. Upon a predetermined drop in temperature the disc will snap back to its normal position as seen in FIG. 4,

causing the contacts to close under pressure of the spring 25.

Under conditions where it is desired to normally maintain the circuit breaker in open position and to close it when subjected to a predetermined rise in temperature the normal position of the disc may be reversed simply by inverting it. In this case its normal position would be the same as the activated position illustrated in FIG. 5.

As clearly illustrated in FIGS. 2 and 3, the photoelectric cell has one terminal 31 connected by a conductor wire 32 to one terminal 33 of the resistor 12, the other terminal 34 of the resistor being in turn connected by a conductor wire 35 to the common blade element of the combined plug and receptacle unit 14 comprising an input-circuit prong part 36 and an output-circuit receptacle contact part 37. The other terminal 38 of the photo-electric cell 10 is connected by a conductor wire 39 of the input circuit to one terminal 21 of the thermostatic circuit breaker 11 which terminal is in turn connected by an input-circuit conductor wire 40 to the input prong element 41 of the plug and receptacle unit 14 paired with the input prong part 36. The other terminal of the thermostatic circuit breaker is connected by an output circuit conductor wire 42 to the output receptacle contact element 43 of the plug and receptacle unit 14 paired with the output receptacle contact part 37 When the apparatus is plugged into an AC power outlet or receptacle, and the appliance to be controlled is connected as seen in FIG. 1, two interrelated circuits are provided, one a heating circuit constantly flowing through the photo-electric cell and the resistor, the other an output switching circuit in which the load is connected. The output switching circuit may be either normally closed or normally open and is activated to either open or close the circuit to the load upon a predetermined rise in temperature occurring in the resistor 12 of the heating circuit. The photo-electric cell acts as a gate and presents a high resistance when it is not exposed to light, so that very little current flows in the heating circuit and consequently the resistor 12 remains below the predetermined temperature required to activate the thermostatic circuit breaker. When exposed to light the photo-electric cell presents a low resistance permitting current to flow, so that the resistor 12 in series with the photo-electric cell will heat up to the predetermined temperature which, through the direct conductance to the thermostatic circuit breaker, will activate the latter. In the case of a lamp to be lighted by night and extinguished by day, the thermostatic circuit breaker would be normally closed when the photoelectric cell was exposed to darkness thus causing the lamp to be lighted. Upon exposure of the photo-electric cell to light the thermostatic circuit breaker would be activated to an open position to cause the lamp to be turned off.

Another embodiment of the invention is shown in FIG. 6, wherein the heating element resistor is enclosed by thermal insulation, thereby to minimize the effects of high or low (particularly low) ambient temperatures. The construction shown in FIG. 6 is essentially similar to that of the preceding figures, and accordingly similar characters of reference have been used to denote like parts.

In accordance with the invention, in addition to the heating element 12 being joined to the cover piece or cap 28 by the epoxy cement 30 so as to be in good heatconducting relation to the cover, there is additionally provided a heat-insulating coating 45 over the cap 28 and heating element 12, such coating having an appreciable thickness a shown. The coating 45 may be of plastic, and is of good heat insulating material such as a silastic composition, or it may be of a structure having air cells. This latter could be, for example, heat-resistant sponge plastic, or it could be matted fiborus material such as that containing asbestos fibers and known commercially as Rock Wool. The heat insulating coating or covering 45 may be formed, as well, to include glass fibers with air spaces between them.

By this construction there is had not only the benefit of increased heat conductivity due to he epoxy cement 30, but also effected the prevention of heat loss by both heat radiation and convection due to the thick heat-insulating covering or jacket 45.

It will be noted that the snap disc 29 operates in a recess in the plastic body 19 whereby the edge portions of the disc at their lower sides are bounded by a rim representing an appreciable thickness of plastic substance of the body 19. This arrangement, in conjunction with the heat-insulating member 45, effectively prevents heat loss to any appreciable extent from the bimetal disc 27. Accordingly, the construction of FIG. 6 has a high thermal efficiency, enabling it to operate properly over a lower or downwardly displaced range of ambient tempertures.

An important advantage of the construction illustrated in FIGS. 4 and 5 is that at the time the resistor 12 is starting to heat, the bimetal disc 27 is located closest to the cap 28 whereby there is had a maximum transfer of heat by radiation from the cap to the disc. In consequence, the disc 27 is more responsive to the initial heating. After the disc has snapped to the FIG. 5 position, the maintenance of such position is easily effected even though the disc 27 is now further spaced from the cover 28, since in addition to the radiation between the disc and cover there is the heating by conduction and convection already mentioned above, plus the reluctance of the disc to snap back because it has passed an unstable center position to a more stable lower position involving the mechanical structure and snap action well known for such discs. This reluctance to return and mechanical snap action are the causes of the lag in the return of the disc when the heat is removed, as is well known in the art. In addition, the heat stored in the cover 28, disc 27 and body 19 are involved in preventing a quick return of the disc, and accordingly drops in ambient temperature are not likely to have any great effect on the disc even though it is spaced further from the cover 28, particularly where there is not appreciable heat loss from the body 19.

An important feature of the invention resides in the actual physical contact which is established between the electrically resistive material of the heating resistor 12 and the cover piece or cap 28. The resistor 12 is of the carbon type, comprising a resistive, carbon-containing body which constitutes the electrically resistive material of the resistor. The said body is in actual intimate physical contact and in intimate heat-receiving relation with the cover piece 28 whereby there is effected an efiicient heat transfer from the resistor to the cover piece. Where the cover piece is of aluminum or copper, such heat is quickly transferred by means of the peripheral portions, to the heat responsive disc 27. This makes for an efiicient device having a relatively good response to lighting of the photoelectric resistor.

Variations and modifications are possible, and portions of the improvement may be used without others.

I claim:

1. A photo-electric light-activated switch apparatus comprising, in combination:

(a) means providing an input circuit,

(b) means providing a closed chamber, said means including:

( 1) a heat-insulating casing having a surface adapted to constitute one wall of the chamber,

(2) a heat-conducting disc-shaped cover piece on said casing, comprising other walls of said chamher,

(0) a circuit breaker connected to said input circuit and including a bimetal snap disc attached at its periphery in the chamber broadside and close to the inside of the cover piece to receive heat therefrom by radiation and convection, said disc having an unattached center portion whereby the bimetallic action thereof is unaltered.

(d) a carbon heating resistor connected to said input circuit and having an electrically resistive elongate cylindrical carbon body extending along and, with its cylindrical wall, engaging and having an intimate physical contact with the exterior of the cover piece so as to be in good heat-conducting relation therewith.

(e) a light-sensitive resistor connected to said heating resistor and said input circuit to control the flow of current through the resistor, and

(f) an output circuit for controlling external equipment, connected with said circuit breaker,

(g) said birnetal disc when cold having its center portion bowed so as to dispose it closer to said cover piece whereby a better heat transfer is effected between the latter and the cold disc,

(g) said circuit breaker comprising switch contacts and a plunger pin operatively connected to said contacts and abuttingly engageable with the center portion of the bimetal disc to be pushed thereby when the disc snaps away from the cover piece in response to heat.

2. An apparatus as in claim 1, and further including:

(a) solid cementitious material securing the heating resister to the cover piece in good thermal relation therewith, said cementitious material engaging the heating resistor and cover piece over relatively large areas of contact.

References Cited UNITED STATES PATENTS JOHN KOMINSKI, Primary Examiner E. R. LAROCHE, Assistant Examiner US. Cl. X.R.

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