Heat deactivated illumination device

An illumination device according to the present invention generally includes a housing, electrical plug prongs, a connector portion associated with the housing for receiving and electrically contacting a light bulb, and a heat sensitive electrical circuit for conducting electrical current from an electrical outlet or other electrical power source to a light bulb received within through the connector portion of the illumination device. Preferably, the heat sensitive electrical circuit includes a bimetallic strip or other heat sensitive mechanism that automatically interrupts the flow of electrical current through the connector portion of the night light when the temperature sensed by the bimetallic strip exceeds a predetermined temperature level. In another embodiment of the present invention, an illumination device is equipped with a successive heat sensitive switching mechanism, in which the power conducted to the light bulb is initially reduced in response to ambient temperature levels exceeding a first predetermined temperature level, with the flow of electrical current to the light bulb being interrupted only in response to a second, higher predetermined temperature level.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates generally to illumination devices, such as 
night lights for example. More particularly, the present invention relates 
to illumination devices including apparatuses for automatically 
deactivating or deenergizing the lights when the immediate ambient 
temperature exceeds a predetermined temperature level. 
A wide variety of night lights and other illumination devices are 
well-known in the prior art. In one common type of night light 
contruction, the light bulb is energized only when the night light is 
plugged into an electrical outlet receptacle and thus remains illuminated 
until the night light is removed from the receptacle. In another very 
common night light construction, a manually-actuable switch is provided so 
that the light bulb can be selectively energized or deenergized while the 
night light is still electrically connected to an electrical outlet 
receptacle. Frequently, in still another common type of night light, the 
manual switch is replaced by a light sensitive switch that automatically 
energizes the light bulb in response to a predetermined low ambient light 
condition and deenergizes the light bulb in response to a predetermined 
high ambient light level. An example of such an automatic, light sensitive 
night light device is disclosed and described in U.S. Pat. No. 3,968,355, 
issued July 6, 1976. Such U.S. patent is assigned to the same assignee as 
that of the present invention, and its disclosure is hereby incorporated 
by reference herein. 
In accordance with the present invention, any of the various types of night 
lights or other illumination devices described above are provided with a 
feature for automatically deactivating or deenergizing the night light 
bulb when the temperature of the immediately surrounding environment 
exceeds a predetermined temperature level. The present invention provides 
such a feature in a construction that is relatively inexpensive to 
manufacture and produce and that does not detract from the appearance of 
the night light device. The present invention further provides such a heat 
deactivating feature in a construction that allows the heat sensitive 
component or components of the night light device to be positioned for 
optimum, expedient detection of the immediately surrounding ambient 
temperature level. 
In order to achieve the objectives mentioned above, an illumination device 
according to the present invention generally includes a housing, 
electrical plug prongs, a connector portion associated with the housing 
for receiving and electrically contacting a light bulb, and a heat 
sensitive electrical circuit for conducting electrical current from an 
electrical outlet or other electrical power source to a light bulb 
received within through the connector portion of the illumination device. 
Preferably, the heat sensitive electrical circuit includes a bimetallic 
strip or other heat sensitive mechanism that automatically interrupts the 
flow of electrical current through the connector portion of the night 
light when the temperature sensed by the bimetallic strip exceeds a 
predetermined temperature level. In this embodiment, the bimetallic strip 
simultaneously can also function as a current conductor, a heat sensor, 
and an electrical switch, and can also be located out of view in the 
housing of the illumination device. 
In another embodiment of the present invention, an illumination device is 
equipped with a successive heat sensitive switching mechanism, in which 
the power conducted to the light bulb is initially reduced in response to 
ambient temperature levels exceeding a first predetermined temperature 
level, with the flow of electrical current to the light bulb being 
interrupted only in response to a second, higher predetermined temperature 
level.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 through 10 depict various exemplary embodiments of the present 
invention as employed in a night light. One skilled in the art will 
readily recognize from the following discussion that the principles of the 
present invention are equally applicable to illumination devices other 
than night lights, as well as to night light devices other than the 
exemplary night light embodiments depicted in the drawings for purposes of 
illustration only. 
FIG. 1 illustrates an exemplary night light 10 according to the present 
invention, with the night light 10 generally including a housing 12 having 
a connector portion 14 for receiving a light bulb 16 electrically 
connected therein. Preferably a pair of electrical prongs 18 and 20 
protrude from the housing 12 and are adapted to be inserted into, and 
electrically interconnected with, an electrical outlet receptacle. 
Although not specifically required in the present invention, the exemplary 
night light 10 can include an optional manual switch 22 for selectively 
energizing or deenergizing the light bulb 16 when the night light 10 is 
plugged into an electrical outlet. Also optionally provided is a 
transparent or translucent enclosure 24 illustrated in phantom lines in 
FIG. 1. 
As perhaps best illustrated in FIGS. 2 through 4, the housing 12 preferably 
includes a threaded opening 28 to allow the light bulb 16 to be threadably 
inserted therein. As shown in FIG. 2, a base connector or conductor 30 and 
a side connector or conductor 32 extend into the threaded opening 28 in 
order to electrically contact base and side electrodes on common light 
bulbs. 
The housing 12 preferably includes a front half portion 36 and a rear half 
portion 38 removably connected to one another by way of a fastener 40 
extending through a bore 42 in the front half portion 36 and a bore 44 in 
the rear half portion 38, as shown in FIG. 3. The manual switch 22 can be 
of the commonly-known push button variety, which includes a movable 
metallic eyelet 48 resiliently biased in an outward direction by a spring 
50, which electrically interconnects the eyelet 48 with an inner end 52 of 
the base connector or conductor 30. The eyelet 48 is movably actuated by a 
push button 54 for selectively moving the eyelet 48 into and out of 
electrical contact with a tab 56 secured to, or integrally formed on, the 
prong 20, as shown in FIGS. 3 through 5. 
The prong 20 in the night light 10 can be secured in place within the 
housing 12 in any of a number of ways, including the interconnection 
between a protuberance 58 extending from the body 60 of the switch 22. 
When the eyelet 48 of the switch 22 is moved into the position shown in 
FIGS. 3 and 5, it electrically contacts the tab 56 on the prong 20 in 
order to electrically interconnect the prong 20 with the base connector 
30, thereby providing electrical communication between the prong 20 and 
the base electrode of the light bulb 16. 
As shown in FIGS. 4 and 5, the side connector 32 includes an inner end 62 
that extends inwardly into the housing 12 to electrically contact the 
prong 18, thereby providing electrical communication between the prong 18 
and the side electrode of the light bulb 16. In accordance with the 
present invention, the inner end 62 of the side connector 32 is a 
bimetallic strip, which can be integrally formed with the side connector 
or conductor 32 or secured thereto. As the immediate ambient temperature 
surrounding the night light 10, and especially the light bulb 16, rises to 
a predetermined temperature level, the thermal energy is conducted 
primarily by direct conduction along a relatively short path through the 
side connector or conductor 32 to its bimetallic strip 62 in order to 
cause the bimetallic strip 62 to move inwardly out of electrical contact 
with the prong 18, as shown in FIG. 7. Thus, the bimetallic strip 62 and 
the prong 18 function as a heat sensitive switch that interrupts the flow 
of electrical current from an electrical outlet 64 to the light bulb 16, 
as illustrated in the electrical schematic diagram of the night light 10 
depicted in FIG. 6. 
It should be emphasized that although the manual switch 22 is included in 
the embodiment of the present invention illustrated in FIGS. 1 through 6, 
such manual switch can optionally be eliminated such that the light bulb 
is energizable only when the night light is plugged into an electrical 
outlet. In other embodiments, many other types of switches can be employed 
in conjunction with the present invention, such as sound actuated switches 
or timer switches, for example. In these various optional constructions, 
the other components and applications of the present invention remain 
substantially similar to those of the exemplary embodiment depicted in 
FIGS. 1 through 7 for purposes of illustration. 
FIG. 4A illustrates an alternate construction that is a variation on that 
of FIGS. 1 through 7, in which elements that are corresponding or similar 
to elements of FIG. 4 are indicated by reference numerals that are the 
same as those in FIG. 4, but with the addition of the suffix "a". 
In FIG. 4A, the bimetallic strip 62a is not necessarily electrically 
interconnected with either the prong 18a or the side connector or 
conductor 32a. The bimetallic strip 62a is, however, at least mechanically 
interconnected with a contact 37a, which is electrically interconnected 
with the side connector or conductor 32a, such as by way of a flexible 
wire or other conductor 35a. The strip 62a thus biases the contact 37a 
toward electrical contact with the prong 18a When the temperature exceeds 
the predetermined level, as discussed above, the bimetallic strip 62a 
urges the contact 37a away from the prong 18a, and biases the contact 37a 
into electrical contact with the prong 18a when the temperature is below 
such predetermined level. In such an alternate construction, the strip 62a 
can be fixed to, or otherwise interconnected with, the housing 12a at a 
portion of the strip 62a that is spaced away from the contact 37a, or the 
strip 62a can also be interconnected with the side connector or conductor 
32a in order to allow heat to be conductively transferred to the strip 62a 
from the light bulb socket. 
FIG. 8 illustrates still another embodiment of the present invention as 
employed in an exemplary night light 110. It should be noted that the 
construction of the exemplary night light 110 is substantially similar to 
that of the night light 10 illustrated in FIGS. 1 through 7, except for 
the differences illustrated in FIG. 8. Accordingly, reference numerals for 
the components of the night light 110 shown in FIG. 8 are the same as 
those of either identical or corresponding components of the embodiment 
depicted in FIGS. 1 through 7, except that the reference numerals in FIG. 
8 are one-hundred numerals higher. 
In FIG. 8, the side connector or conductor 132 includes a separate, 
discrete bimetallic inner end 162 secured to the night light housing 112, 
such as by way of an electrically non-conductive post or tab 166. The 
bimetallic inner end or strip 162 is fixedly secured to the post 166 at an 
intermediate position between an inner portion 168 and an outer portion 
170 of the bimetallic strip 162. 
A diode 172 electrically interconnects the electrical prong 118 and the 
bimetallic strip 162 by way of electrical wires 174 and 176, with the wire 
176 being electrically attached to the bimetallic strip 172 at a location 
generally adjacent the non-conductive post 166. Preferably, the distance 
between the post 166 and the area of engagement of the outer portion 170 
with the side connector or conductor 132 is less than the distance between 
the post 166 and the area of engagement of the inner portion 168 with the 
electrical prong 118. Thus, as the ambient temperature exceeds a 
predetermined level, heat is conducted through the side connector 132 to 
the bimetallic strip 162, causing the inner portion 168 to deflect out of 
electrical contact with the electrical prong 118, as shown in FIG. 8, 
prior to the breaking of the contact between the bimetallic strip 162 and 
the side connector or conductor 132. This deflection interrupts the flow 
of electrical current from the electrical prong 118 to the side connector 
or conductor 132, thus causing the electrical current to instead flow from 
the electrical prong 118, through the diode 172 and the outer portion 170 
of the bimetallic strip 162 to the side connector or conductor 132. In 
this condition, the power to the light bulb of the night light 110 is 
therefore reduced, which in turn tends to reduce the heat generation of 
the light bulb in order to lower the ambient temperature in the area 
immediately surrounding the night light 110. 
If the ambient temperature immediately surrounding the night light 110 
rises to exceed a second, higher predetermined temperature level, 
notwithstanding the reduction of power to the light bulb, the outer 
portion 170 of the bimetallic strip 162 then deflects inwardly out of 
engagement with the side connector or conductor 132 in order to totally 
interrupt the flow of electrical current to the light bulb. Thus, the 
arrangement in the embodiment of the present invention illustrated in FIG. 
8 provides for successive heat sensitive switching, initially reducing the 
power conducted to the light bulb of the night light 110 in response to a 
first predetermined ambient temperature level, and then deenergizing the 
light bulb if the ambient temperature exceeds a second, higher 
predetermined temperature level. 
It should be emphasized that the successive heat sensitive switching 
arrangement illustrated in FIG. 8 can be employed in night lights or other 
illumination devices irrespective of whether such illumination devices are 
also equipped with manually actuable switches or other switches. 
FIGS. 9 and 10 illustrate another application of the present invention in a 
night light 210, which is equipped with a photoelectric switch 280 adapted 
to electrically interconnect and energize the light bulb in response to 
predetermined low ambient light conditions and to electrically disconnect 
and deenergize the light bulb in response to predetermined higher ambient 
light conditions. Because many of the components are identical with, or 
correspond to, components of the night light 10 illustrated in FIGS. 1 
through 7, such identical or corresponding components are identified by 
similar reference numerals in FIGS. 9 and 10 that are two-hundred numerals 
higher than the corresponding reference numerals of FIGS. 1 through 7. 
The night light 210 preferably includes a circuit board 282, which can 
include electric or electronic components well-known to those skilled in 
the art, for purposes of causing the above-discussed light-responsive 
energization and deenergization of the light bulb of the night light 210. 
As shown in FIGS. 9 and 10, the circuit board 282 preferably includes a 
stepped or recessed portion 284 in order to provide clearance for movement 
of the bimetallic strip or inner end 262 of the side connector 232 when 
the bimetallic strip 262 deflects away from, and out of electrical contact 
with, the electrical prong 218, in the same manner as described above in 
connection with FIGS. 1 through 7. Thus, the night light 210 with its 
photoelectric switch 280 is equipped with the same heat sensitive 
switching apparatus as described above in connection with the night light 
10. It should further be noted that the general arrangement depicted in 
FIG. 8, in connection with the exemplary night light 110, can also be 
alternately substituted for the arrangement shown in FIGS. 9 and 10 and 
can thus be employed in connection with a photoelectrically actuable and 
deactuable night light, or alternately in connection with night lights 
that have no other switching mechanism at all. 
It should be further be noted in connection with all of the various 
embodiments of the present invention depicted in the drawings and 
discussed above, that the bimetallic strip in each of these embodiments 
can also alternately be arranged and positioned to engage the opposite 
sides of the electrical prongs and side connectors from those shown in the 
drawings. Thus, because of such flexibility, along with the physical 
arrangements shown for purposes of illustration in the drawings, the heat 
sensitive features of the present invention can be employed in night 
lights or other illuminations devices substantially without detracting 
from the appearance of such devices or adding to their overall physical 
dimensions. Furthermore, because of the short, straightforward and direct 
physical path between the side connectors or conductors and the bimetallic 
strips discussed above, the ambient temperature level immediately 
surrounding the light bulbs of the illumination devices can be very 
rapidly and directly sensed, and the heat sensitive switching mechanism of 
the present invention can accordingly respond very quickly to elevated 
temperatures. 
The foregoing discussion discloses and describes exemplary embodiments of 
the present invention. One skilled in the art will readily recognize from 
such discussion, and from the accompanying drawings and claims, that 
various changes, modifications, and variations may be made therein without 
departing from the spirit and scope of the invention as defined in the 
following claims.