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PORTABLE LIGHTING DEVICE HAVING
EXTERNALLY ATTACHED VOLTAGE
CROSS-REFERENCE TO RELATED CASE
This is a file wrapper continuation of application Ser. No. 08/148,074 filed Nov. 1, 1993, now abandoned for Portable Lighting Device Having Externally Attached Voltage Tester.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The instant invention relates generally to portable lighting devices such as battery-powered flashlights and lanterns, and particularly to a built-in device for indicating the level of charge or capacity of the batteries contained therein.
2. Discussion of the Related Art
Flashlights and a majority of portable lanterns are batteryoperated using either non-rechargeable or rechargeable batteries. One problem commonly associated with these batteries is determining the useful or remaining life of the battery. If the batteries are already in a flashlight or portable lantern, the quickest way to determine the strength of the battery is by turning the flashlight or lantern on. If the incandescent or fluorescent lamp illuminates, most individuals are satisfied that the batteries are good. However, if the flashlight or portable lantern does not illuminate, then the question is whether the problem lies in the batteries or the lamp. The user must then either replace the batteries in the flashlight with new batteries and/or the lamp, or remove the existing batteries and/or the lamp and test them.
Several devices have been developed for testing batteries to determine the freshness or state-of-charge of the cell. For example, U.S. Pat. Nos. 4,723,656 and 5,128,616 disclose a blister-type package for new batteries with a battery condition indicator built into the blister portion of the package. The blister can be deformed to place the tester across the terminals of the battery to be tested. The tester employs a thermochromic material in combination with a resistive element. The flow of current produces a temperature gradient across the resistive element which, in turn, causes a color change in the thermochromic material to indicate the stateof-charge of the battery. As mentioned, the testers are associated with the package in which the batteries are purchased. Once the batteries are removed from the package, the package is usually discarded and from then on the state-of-charge of the battery is indeterminate.
U.S. Pat. Nos. 4,702,563, 4,702,564, 4,726,661, and 4,737,020, disclose a flexible battery tester which has a conductive circuit pattern associated with a layer of thermochromic material. The flexible member is bent so that the circuit pattern can contact the positive and negative terminals of the battery to be tested and, again, the temperature gradient is observed in the thermochromic material and correlated with the state-of-charge of the battery. All of these testers suffer from the same deficiency in that the tester is a separate element, which in the case of the package, is usually thrown away, and in the case of the above patents, can be lost or misplaced. In either event, the state-of-charge of the battery is indeterminate once the testing device is no longer available.
U.S. Pat. No. 4,876,632 discloses a flashlight containing a device for indicating the level of charge on a battery. The battery life indicator is a module that is mounted between the flashlight head or lamp assembly containing the light reflector and a battery housing assembly for holding the batteries.
The battery life indicator module contains an indicator, such as a light-emitting diode (LED). Internal to the battery life indicator module is a circuit which measures the battery level and activates the indicator to display the battery level.
5 The module also provides the necessary electrical connection between the batteries and the light lamp of the flashlight. The battery life indicator is activated by the On/Off switch of the flashlight so that the power is not drained when the flashlight is not in use. However, when the flashlight is
10 turned on, the battery-life indicator module and its associated circuit are also powered and remain on while the flashlight is on. In the event the flashlight lamp burns out, and the operator fails to notice that the battery-life indicator is activated, the tester will result in a discharge of the
U.S. Pat. No. 4,962,347 discloses a battery-powered flashlight or portable lantern having a built-in device for determining the strength, voltage or capacity of the batteries. The flashlight or lantern includes a housing which holds the
20 batteries and which receives an electrically powered light source mounted thereon which is energized by the batteries. A battery-testing circuit is mounted in the housing having a display which is detectable from the outside of the housing. A three-way switch mounted in the housing is placed in a
25 first position to connect the light source with the batteries, and in a second position to connect the battery-testing circuit with the batteries, and a third position to disconnect the batteries from both of the light and the battery-testing circuit.
30 U.S. Pat. No. 4,432,041 discloses a portable lighting device which includes circuitry for detecting a low voltage condition of the batteries. Upon the detection of a low voltage condition, the circuitry provides an intermittent sound that is indicative of the low voltage condition. A
disadvantage associated with this circuitry is that the tester is constantly "ON" in order to monitor the voltage level. Furthermore, the tester circuitry only provides an indication when the voltage level of the batteries are below a certain level. There is no indication as to the remaining life of the 40 battery and the state-of-charge of the battery is indeterminate.
In view of these disadvantages, a battery tester forming an integral part of the flashlight housing which is not in series 45 with a circuit operating the flashlight is desired.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a flashlight or lantern includes a housing for retaining at least one battery 50 and a light source attached to the housing and operable by the battery, and a laminated battery tester fixed to the exterior surface of the housing and having one end operably connected to one pole of the battery and an opposite end operably connectable to an opposite pole of the battery 55 wherein the laminated battery tester provides an indication of the strength of the battery. The battery tester includes a flexible substrate having an indicator material located on one side of the substrate and a conductor located on a side opposite thereto. The conductor has one end operably congo nected to the one pole of the battery and an opposite end is operably connectable to the opposite pole of the battery.
In another aspect of the invention, a flashlight or lantern housing has first and second terminals, each in electrical continuity with one pole of at least one battery contained 65 within the housing. A display circuit mounted on the exterior of the housing has a first end in electrical contact with the first terminal and a second end engageable with the second
terminal whereby depression of the second end results in a current to flow through the display circuit and providing an indication of the strength of the battery.
According to yet another aspect of the invention, a battery tester is provided for use on the exterior of a flashlight or 5 lantern having a housing for retaining one or more batteries and a light source operably connected through a switch to the battery. In this environment, the battery tester includes in combination a conductor fixed to the exterior of the housing and having a first end operably coupled by a terminal to one 1° pole of the battery and a second end in switching relationship to a second terminal operably coupled to an opposite pole of the battery. The conductor includes a region between the two ends having a controlled resistance to an electrical current. A responsive display overlying the conductor dis- :5 plays the remaining capacity in the battery when electrical current flows through the conductor upon the closing of the switch between the conductor second end and the second terminal. In the case where the flashlight or lantern housing is metallic, the housing serves as one terminal for the 20 conductor. The opposite terminal of the flashlight or lantern is insulated from housing and operably connectable with the conductor.
In one form of the invention, a Belleville switch mechanism is used to make the electrical connection between the 25 conductor and the one terminal of the flashlight or lantern. The switching mechanism includes a conductive plunger having one end overlain by the end of the conductor. The plunger is held away from the flashlight or lantern terminal by a Belleville spring disposed between the plunger and the 30 housing. To activate or close the switch, the operator depresses the plunger which contacts the terminal allowing current to flow through the conductor and activate the display. Release of the switch results in the Belleville spring urging the plunger away from the terminal and opening the 35 circuit.
The battery tester of this invention will function to indicate the battery state-of-charge even if the flashlight or lantern lamp is not functioning, unlike some prior testers 4Q where the lamp remains in series with the tester and the batteries. Another advantage of this invention is the low profile, easy construction and low cost to manufacture.
BRIEF DESCRIPTION OF THE DRAWING
The above advantages, purposes and other features of the invention will become apparent from a study of the following detailed description taken in conjunction with the appended drawing figures, wherein: 50
FIG. 1 is a side elevational view of a flashlight;
FIG. 2 is an enlarged fragmentary plan view of a battery tester on the flashlight shown in FIG. 1;
FIG. 3 is a fragmentary sectional view of one embodiment of the battery tester taken along line III—III shown in FIG. 55 2;
FIG. 4 is a fragmentary sectional view of a second embodiment of the battery tester taken along line IV—IV shown in FIG. 2;
FIG. 5 is an exploded view of the battery tester shown in FIG. 3;
FIG. 6 is an exploded view of the battery tester shown in FIG. 4; and
FIGS. 7 and lb are fragmentary sectional views of an 65 alternate embodiment of a switch for use in the battery tester shown in FIGS. 2-6.
DETAILED DESCRIPTION OF PREFERRED
Referring to FIGS. 1 and 2, a flashlight or portable lantern 10 generally includes an elongate tubular body or housing 12 having a first end 14 and a second end 16. Tubular body 12 contains a longitudinal battery retention chamber which is dimensioned to accommodate one or more dry-cell batteries used to operate a lamp assembly 18 (not shown in detail) mounted to the first end 14 of tubular body 12. The second end 16 of tubular body 12 may be sealed or receive an end cap 20 which may be removed to insert and remove the batteries received within the battery retention chamber of tubular body 12. Lamp assembly 18 may be operably coupled to the batteries by a switch 22 such as a push button, slide or rotary type.
In a preferred embodiment, flashlight or lantern 10 also includes a battery tester 24 which is fixed to the exterior of tubular body 12. As shown generally in FIGS. 2-3, battery tester 24 is preferably a low profile circuit made from a multi-laminate film adhered to the exterior of tubular body 12. If desired, battery tester 24 may be positioned within a recess 25 formed in the exterior of tubular body 12 which is of generally the same dimension as tester 24. Tester 24 includes an indicator or display area 26 preferably located on a decorative background 28 which is complimentary to the overall exterior design of flashlight 10. Tester 24 also includes a region 30 indicated thereon, preferably by a decorative ink, to indicate the location of a switch which is depressed to close the circuit to activate the display.
Battery tester 24 is comprised of a means for completing the circuit between the poles of the battery within tubular body 12, a means for responding to the capacity of the battery and a means for indicating the capacity of the battery. A means for completing the circuit can be a tester circuit that is comprised of electrically conductive material such as a metallic foil, or a metallized plastic layer. Other examples include electrically conductive paints or inks, such as those that contain graphite, carbon, or metals or combinations thereof. The electrically conductive material is configured to have first and second ends that are connected to each other via an area of controlled resistivity. The first end is provided to make contact with a first terminal of the flashlight which is, in turn, in contact with one pole of the battery contained therein, and the second end is provided to make contact with a second terminal of the flashlight, which, in turn, is in contact with the opposite pole of the battery contained therein. These terminal contact ends are or will be connected to the terminals of the battery to complete the test circuit. Thus, when the tester circuit is completed, electric current can flow through the area of controlled resistivity. The term "controlled resistivity" means that the resistance is controlled to be within the range to activate the responsive means.
The resistance in the area of controlled resistivity can vary or it can be constant. In one embodiment, it is desired to have a varying resistance to indicate the relative remaining useful life of a battery. For example, the current flowing through the tester circuit will generate a specific temperature. The temperature achieved will be proportional to the amount of current supplied by the battery. Thus, the area of controlled resistivity can be of varying width, e.g., tapered, or of varying thickness to achieve the temperature gradient. Alternatively, the area can be of constant width and constant thickness. A further alternative would involve the use of different conductive materials having different resistivities in the area of controlled resistivity. In addition, when using
thermochromic materials, materials activated at different temperatures can be used along an area of constant resistance, or continuous or discontinuous segments of a thermochromic material could be used along an area of varying resistance. 5
The testing means can be further comprised of means for connecting the tester circuit to the terminals of the flashlight. This means can be terminal connectors that connect the opposite poles of the battery with the terminal contact ends of the tester circuit. Preferably, one terminal contact end of 10 the circuit is out of contact with the terminal of the flashlight so that the tester circuit is open. In this embodiment, the testing means is further comprised of means for turning the tester circuit on, such as a switch. In a preferred embodiment of the invention, one end of the circuit is permanently in 15 contact with one pole of the battery through a terminal in the flashlight tubular housing. The opposite end contains a switch which places it in electrical contact with a second terminal in the flashlight housing, which is in electrical continuity with the opposite pole of the battery contained 20 therein. The switch of the circuit includes a small opening in a layer between the flashlight terminal and the end of the tester circuit. By forcing the end of the circuit into contact with the flashlight terminal through the opening, the switch is closed and the tester circuit is completed to test the battery. 25 This contact can be conveniently made by applying finger or thumb pressure to the switch area. When the force on the switch is removed, the switch opens and interrupts the circuit.
The testing means further comprises a means for indicat- 30 ing the capacity of the battery. The indicating means will be in responsive contact with the area of controlled resistivity and will respond to and indicate a state that is present in that area. For example, a temperature increase will be generated in that area when a current flows through the tester circuit. 35 If the indicating means is a thermally sensitive material, then it is in thermally transferable contact with the area of controlled resistivity. If the indicating means is an electrical field or voltage sensitive material, then the indicating means will be in electrical contact with the area of controlled 40 resistivity. The indicating means will indicate the capacity of the battery to the consumer. This indication can be qualitative such as a "good" or "bad" reading, or quantitative such as a remaining percentage of useful life.
In one embodiment, the indicating means can be a ther- 45 mally sensitive material that is in responsive contact with the area of controlled resistivity of the tester circuit. Thus, the heat generated in the area of controlled resistivity in the tester circuit can be transferred to the thermally sensitive material. The thermally sensitive materials change color in 50 response to a temperature change. The material is readily viewable to a consumer so that, based on the color change, the consumer can determine whether the battery is good or needs to be replaced.
To facilitate a color change effect, the thermally sensitive 55 material can be placed over a contrasting color layer. This color layer can be applied by printing directly onto the film base or onto the electrically conductive circuit. A message can also be printed onto the contrasting color layer that can be viewed by the consumer when the thermally sensitive 60 material changes color. An alternative means of providing a message can employ a stencil in the form of a thermally non-conductive layer, e.g., a layer of double-faced tape in which the message is cut out of the thermally nonconductive layer so that a thin air insulation layer is left in 65 that area under the thermally sensitive material. When the tester is activated, this cut-out message portion, which has
poorer thermal conductivity than the surrounding area, results in the thermally sensitive material directly over the message area changing color, while the surrounding thermally sensitive material, which serves as a heat sink, remains its original color, thus outlining the message. The stencil can be reversed so that the message is made of the thermally non-conductive layer and is surrounded by the air insulation layer. When this tester is activated, the thermally sensitive material directly over the message portion will remain its original color because of better thermal conductivity, and the surrounding thermally sensitive material over the air insulation layer will change color, thereby outlining the message.
Examples of thermally sensitive materials are liquid crystal materials and thermochromic inks. The indicating materials can be used singularly or in combination. For example, in one embodiment, layers of different indicating material are employed. The layers are activated at different temperatures or states and can be designed to change different colors at different temperatures. For example, the layers of different indicating material are arranged in decreasing temperature of activation with the lowest temperature material in the top layers. Alternatively, the indicating material can be designed to test the battery at different ambient temperatures by using materials that activate at different temperatures. The material activatable at the corresponding temperature would be associated with the different circuits. For example, the label could be designed with a window for testing at 40° F., a window for testing at 70° F. and a window for testing at 90° F. Depending on what the ambient temperature is, the consumer would look at the corresponding window. Examples of suitable liquid crystal materials are of the cholesteric type, such as cholesteryl oleate, cholesteryl chloride, cholesteryl caprylate and the like. Examples of suitable thermochromic inks include those comprised of a die, developer and desensitizing agent that are disclosed in U.S. Pat. No. 4,835,475, incorporated herein by reference. Such inks are available from Matsui International Corp. of El Segundo, Calif, and Sakura Color Products Corporation of Osaka, Japan.
In another embodiment of this invention, the indicating and responding means can be materials that respond to a voltage change or an electric field. These materials are responsive directly to the remaining capacity of the battery as the current flows through the tester circuit, and so will be disposed in electrically responsive contact with the area of controlled resistivity. Materials for this purpose are known as electrochromic materials and are commercially available. For example, one such provider of such materials is the Donnelly Corporation of Holland, Mich.
The battery tester of this invention can also comprise additional insulative layers, printing layers, protective layers and the like. Suitable materials for use as the different layers include plasticized or unplasticized polyvinyl chloride, polyester, metallic films, paper and the like, and they are prepared by known methods, such as laminating the layers together and adhering to each other via an adhesive. In embodiments where conductive ink will be in contact with the adhesive, it is desirable to employ a primer layer or sealant layer between the conductive ink and the adhesive. Suitable primers and adhesives include UV-cured dielectric materials such as Dielectric LV-3728-39 from Emerson & Cuming Inc. of Woburn, Mass., dielectric ML-25198 from Acheson Colloids of Port Huron, Mich., and liquitex acrylic gesso available from Binney & Smith Inc. of Easton, Pa.
In one embodiment of the flashlight having the externally attached battery tester 24, flashlight 10 has an elongate