Abstract:
A convoluted, bi-metallic test strip is inserted between a battery and an electrical circuit within a flashlight having a nonzero, quiescent, current drain. Squeezing the test strip permits consumers to temporarily test the flashlight. The strip is then removed by consumers after the flashlight has been purchased.

Description:
TECHNICAL FIELD 
     The invention relates to low cost, disposable test switches. More specifically, the invention relates to low cost, disposable test switches for use by consumers to determine an electrical characteristic of a battery-operated device. 
     BACKGROUND OF THE INVENTION 
     Low cost test switches have recently become available so that consumers can verify a characteristic of an electronic device such as a battery. “Test strips” are presently available which permit a consumer to determine the level of charge on a battery (e.g. AA size, AAA size, etc.) by depressing a strip, often integrated into the battery packaging, against the positive and negative terminals of the battery. A current flows through the strip generating heat. A thermochromic material within the strip then changes color to indicate the charge on the battery. U.S. Pat. No. 6,054,234 to Weiss et al. and U.S. Pat. No. 5,925,480 to Shacklett III, et al., the disclosures are incorporated herein by reference, disclose devices and techniques for making battery test strips which illustrate the state of the art with respect to this technology. While devices of this type are useful for their intended purpose, they are not suitable for testing an electronic device which is connected to the battery. 
     In the consumer flashlight art, consumers often desire to test the flashlight prior to its purchase. Many such flashlights are offered for purchase with batteries already installed. Provided that the flashlight is provided with a momentary on/off switch of the pushbutton type, manufactures often provide packaging which permits operation of the momentary pushbutton switch through the packaging so as to permit consumers to perform such examinations of the flashlight. Traditionally, flashlights of this type have utilized one or more dry cells in series with an incandescent bulb, all contained within a plastic or metallic housing. 
     Recent advances in semiconductor technology have provided artisans in this area of technology with the opportunity to use light-emitting diodes (hereinafter occasionally “LEDs”) as a primary light source and substitute for an incandescent bulb. LEDs are far more efficient with respect to current consumption as compared to incandescent bulbs. Due to this increased efficiency, it has ben possible to replace the standard plurality of “D” cells, “AA” cells, or the like with so-called “button cells” having a small discoid shape. An early example of a convenience flashlight of this type is disclosed in U.S. Pat. No. 5,386,351 to Tabor, issued on Jan. 31, 1995, entitled “Convenience Flashlight.” The disclosure of the Tabor patent is incorporated herein by reference. The device disclosed by Tabor has a two-piece, snap-fit case containing a discoid battery, an LED, and a pushbutton penetrating one of the snap-shut case halves. As is well known by those of ordinary skill in the electronics art, LEDs have two legs. One leg is connected to the anode of the LED, while the remaining leg is connected to the cathode. Tabor advantageously positions one of the LED legs adjacent to one side (i.e., one terminal) of the button battery while the resilient nature of the remaining leg resides in a normally spaced-apart relationship from the other side (i.e., other terminal) of the battery. The pushbutton is used to depress this remaining leg against the other terminal of the button battery, thereby completing the electrical circuit and illuminating the LED. Releasing pressure from the button permits the LED leg to resiliently resume its initial position out of contact with the other terminal of the button battery, thereby breaking the electrical circuit and extinguishing the LED. Convenience flashlights of the type disclosed in Tabor can be advantageously tested by the consumer at the point of purchase, even if the product is packaged, providing that the packaging permits the consumer to depress the button. 
     A more advanced version of a convenience flashlight employing a button cell battery and an LED illumination source is disclosed by Allen, the inventor herein, in International Publication No. WO 01/77575 A1 published on Oct. 18, 2001, entitled “Portable Illumination Device.” The Allen device incorporates a microprocessor, or micro controller circuit, into the LED/battery/pushbutton circuit to provide the illumination device with enhanced features, including a blinking mode, an automatic off mode, a low power mode, etc. These factors are all controlled by sequential depression of the pushbutton from the logical operation of the microprocessor or micro controller. One disadvantage of the device disclosed by Allen as compared to the device disclosed by Tabor is that although modern microprocessors or micro controllers have relatively low current drains even while in a “sleep mode” (i.e., while not performing any logic functions) the quiescent current drains of such devices are nonzero. Thus, a button cell LED-type personal flashlight, which might ordinarily have a shelf life of over ten years, may only have a shelf life of approximately two to three years if such device incorporates a modern microprocessor or micro controller. To avoid this result, the manufacturers of devices such as the portable illumination device disclosed in the Allen International Publication may insert a strip of insulating material between one terminal of the button cell battery and an electrical contact of the micro controller, microprocessor, or other circuit element to prevent the circuit from being completed. Upon purchasing the device, the consumer merely removes this insulating strip to render the device functional. If the device is provided with a clamshell-like, snap-fit case, often the insulating strip can be removed from the device with a sharp tug on a free end of the insulating strip without opening or closing the device case. 
     Although the aforementioned insulating strip solves the problem of undesirable current drain while personal illumination devices of the type described are on store shelves, the insulating strip prevents consumers from being able to test the personal lighting device while the device is in its packaging. This result is undesirable from a marketing point of view. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a low cost, temporary switch for installation in battery-powered devices which may be actuated by a consumer while the device is in its packaging for testing of the device. 
     It is a further object of the present invention to provide for a temporary test switch which achieves the above object and which also is readily removable by the consumer after the device has been purchased and removed from its packaging. 
     It is yet another object of the present invention to provide for a test switch which achieves the above objects and which is also inexpensive to manufacture and easy to use. 
     The invention achieves the above objects, and other objects and advantages which will be apparent from the description which follows, by providing a low cost, convoluted test strip for testing a battery-powered device. The strip is positionable between terminals of a power supply circuit incorporating the battery. As used herein, the term “battery” encompasses any self-contained power source, such as dry cells, wet cells, fuel cells, or any other device of similar type which may be hereinafter devised. The test strip of the present invention incorporates an elongated, insulating layer defining upper and lower sides. Conductive material is applied on the upper side and the lower side, but the upper and lower sides are not normally in electrical conduction with each other. One portion of the strip is preferably placed in the electrical circuit of a portable, battery-powered device to inhibit electrical conduction through the device. Another end of the strip is provided with a convolution such that a portion of the lower conductive surface is suspended in a spaced-apart relationship with respect to an adjacent portion of the upper surface. Nevertheless, the juxtaposed upper and lower conductive surfaces are sufficiently close together such that pressing the surfaces together creates electrical continuity between the upper and lower surfaces of the strip which are interposed within the electrical circuit so that the electrical device, such as a flashlight, may be tested by consumer. The invention is especially well adapted for use in a packaged product in which the consumer nevertheless can squeeze the packaging such that the convoluted potion can be compressed to test the device within the packaging. 
     In the preferred embodiment of the invention, the elongated, flexible insulating layer is both flexible and resilient, so that upon releasing the cantilevered portion of the strip with respect to the non-cantilevered portion, electrical continuity is discontinued and the test strip may be repeatedly used by various consumers until the device is removed from its packaging and the test strip removed from the device. In one preferred embodiment of the invention, the convoluted test strip has a first fold, which is at approximately a 45-degree angle with respect to the main body or non-cantilevered portion of the test strip, and wherein the convoluted test strip is provided with a second fold at an angle of approximately 135 degrees with respect to the first fold, such that the test strip is doubled back upon itself, with the cantilevered and non-cantilevered portions being substantially parallel to one another. In an alternate embodiment of the invention, the convolution is provided by twisting the test strip along its longitudinal axis by approximately 180 degrees and then bending the test strip back upon itself so that the opposite, conductive sides of the test strip are facing one another in a manner similar to the first embodiment. 
     In the preferred embodiment of the invention, the insulated layer may be formed of a polymer material, and the conductive layers may be formed of a metallic material, such as copper or aluminum. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric, perspective view of a squeeze-type, LED flashlight incorporating a convoluted test strip of the present invention. 
     FIG. 2 is a fragmentary, isometric view of the test strip, illustrating the position of a first fold of the invention. 
     FIG. 3 is partial, isometric view of the test strip showing a tab portion being formed by executing the first fold. 
     FIG. 4 is a partial, isometric view of the test strip showing the tab portion being doubled over the remaining portion of the test strip by means of a second fold. 
     FIG. 5 is a schematic representation of the test stip in unfolded condition, integrated into an electrical circuit. 
     FIG. 6 is a partial, isometric view, illustrating an alternate embodiment of the convolution of the test strip from the previous Figures. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A convoluted test strip in accordance with the principles of the invention is generally indicated at reference numeral  10  in the various Figures of the attached drawings, wherein numbered elements in the Figures correspond to like numbered elements herein. The test strip is shown in use with an LED, squeeze-type flashlight generally indicated at reference numeral  12 . The flashlight is of the type having a clamshell case  14 , commonly manufactured from a thermoplastic material, having an upper half  16  and a lower half  18  which are engaged in a “snap fit.” The flashlight includes an LED  20  which is part of an electrical circuit incorporating a discoid battery  22 , and a logic circuit  24  in the form of a microprocessor or micro controller, all of which are schematically represented in FIG.  5 . 
     As best seen in FIG. 5, the test strip is provided with a flexible, insulating layer  26  which can be manufactured from an appropriate thermoplastic, such as polyethylene terephthalate (PET). The insulating layer  26  preferably has a thickness of approximately 0.1 mm (0.004. inch). Polyester sheeting having a thickness of between approximately 2-3 thousands of an inch has also been used successfully. The insulating layer defines upper and lower surfaces which are coated with an upper conductive layer  28  and an lower conductive layer  30 . The conductive layers are preferably metallized foil, such as copper or aluminum, and may be applied by any conventional means, such as by an adhesive or by vapor deposition. A copper coating having a thickness of approximately seventeen microns is preferred. A similar thickness of aluminum is also acceptable. Prefabricated material from which strips  10  can be cut is available from Sheldahl, Inc., Chandler, Ariz., U.S.A. The sheet material is preferably cut into small strips approximately three inches long by one-eighth inch wide, such that the upper and lower conductive layers  28 ,  30 , are not in electrical continuity with one another. 
     As shown in FIGS. 1 and 5, one end of the test strip is placed inside of the case  14 , such that the strip inhibits electrical continuity through the circuit shown in FIG. 5 when the strip is in its rest position. Preferably, the strip is inserted between the logic circuit  24  and the battery  22 , although in theory positioning the strip in any position within the electric circuit would be satisfactory. 
     In order to permit the test strip to perform as a temporary switch, the test strip is preferably folded along a first fold line  40  shown in FIG.  2 . The first fold line preferably forms an approximately forty-five degree angle with respect to an edge  44  of the test strip, as best seen in FIG.  2 . The first fold line  40  delineates an end tab portion  46  from a main body portion generally indicated at reference numeral  48 . The end tab portion  46  is then folded over itself at second fold line  50  and as shown in FIG. 4 so as to assume the position shown in FIG.  4  and in FIG. 1, wherein the end tab portion  46  is cantilevered over the main body portion  48 . Fold line  50  forms an angle of approximately one-hundred-thirty-five degrees with respect to the edge  44  of the test strip. In this configuration, it is apparent that the lower conductive layer  30  on the end tab portion  46  will be cantilevered above the upper conductive layer  28  on the main body portion  48  in a spaced-apart relationship due to the thickness of the folded-over material in the vicinity of the first and second fold lines  40 ,  50 . It has been found that by using a thermoplastic material of the thickness described above and by sufficiently deforming the strip at the folds with gentle finger pressure (beyond its limit of elastic deformation), the strip  10  is permanently deformed so that it will not resume the shape shown in FIG.  5 . Nevertheless, the first and second folds continue to maintain the upper and lower conductive layers in a spaced-apart relationship in the vicinity of the end tab portion  46 . The consumer may therefore merely compress the end tab portion  46  in its cantilevered configuration, shown in FIGS. 1 and 4 against the main body portion  48  thereunder, so as to complete the electrical circuit and temporarily activate the logic circuit  24  whereby the LED  20  is illuminated so as to test flashlight  12 . In this manner, undesirable discharge of the battery  22  through the circuit is avoided while the flashlight  12  is on the shelf prior to sale. It is believed that the shelf life of the product with the test strip  10  installed will be on the order of approximately 10 years, whereas the same flashlight  12  without the test strip  10  installed would have a shelf life of only approximately two to three years. 
     An alternative embodiment of  10 ′ is shown in FIG. 6, in which the end tab portion  48  is twisted about a longitudinal axis  60  of the test strip by approximately 180 degrees. The end tab portion  46  is then folded over, as shown by arrow  62 , such that the lower conductive layer  30  will be cantilevered above the conductive layer  28 , as illustrated in FIGS. 1 and 4 of the previous embodiment. In this alternate embodiment however, the insulating layer  26 ′ cannot be excessively resilient, otherwise the test strip  10 ′ will lose the twist generally indicted at reference numeral  63 , which forms the convolution of this alternate embodiment. A permanently deformable insulating material such as cardboard is preferred. This alternate embodiment, therefore, is apparently only useful for a single test, at which point relieving pressure from the convoluted portion of the test strip  10 ′ will not necessarily result in the discontinuance of electrical continuity. Those of ordinary skill in the art will of course appreciate that the product packaging could be designed so as to provide the resilient characteristic between the bent-over end tab portion  46  and the main body  48  to provide enhanced functionality for this embodiment. 
     Those of ordinary skill in the art will conceive of other alternate embodiments of the invention upon reviewing this disclosure. By way of example and not limitation, the test strip could be used with electrical devices other than flashlights. Thus, the invention is not to be limited to the above description, but is to be determined in scope by the claims which follow.