Abstract:
An installation-activated, battery-powered hazard device with an on/off switch mechanism and separable into complementary portions. A first of the portions contains essentially all operative electrical circuitry, including sensor(s), a source of power, and a circuit break feature; while its complement provides various small structures or morphology that aid or facilitate closure of the break. Cooperative functioning of the structures is consistent with a stylized mating or unmating of the portions. Multiple versions of the unique multiuse or recyclable switching device are disclosed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to operational electric switches for wall- or ceiling mounted devices such as hazard detectors, and more particularly, to a repetitively useable on/off switch which is engaged or disengaged whenever the device/detector is installed or uninstalled, respectively. 
     2. Background Information 
     Many hazard detectors, such as fire, smoke, gas, heat, and proximity (motion) types are known and used in residential dwellings and commercial buildings. These are also termed ambient condition monitors or detectors and operate off internal and external power sources. The internal power sources are generally single or ganged batteries of practically every commercially available type, including those described generically as long-life. Although the present invention does not apply only to use of the long-life battery, its greatest utility is realized therewith, because modern production methods and economics have fostered the idea of transshipping detectors, and other battery-using devices, with the batteries installed. Indeed, in some instances, the device contains the battery power supply installed, and even hard-wired, into the operative circuitry; but, this feature can only be employed where care is taken to comply with current industrial safety and transportation laws that may not allow movement of “hot” or “active” electrical devices. Moreover, from the perspective of battery life, it is generally undesirable to have the device “hot” or “active” during shipment and while the device remains in a retailer&#39;s inventory. It is to exploit this quiescent, yet battery-installed, feature that the instant invention is provided and prior art now discussed. 
     In U.S. Pat. No. 5,578,996, issued for a LONG LIFE DETECTOR, there is disclosed a seemingly conventional ambient condition, surface-mountable detector which contains within its construction: a mounting bracket; a base, which contains part of a single-use, frangible, and rotatable switch mechanism, the complementary switch portion, borne on a circuit board, which is attached also to the base and secures a hard-wired, long-life battery, and a protective cover. The detector remains inactive until its installation, which requires insertion of a flat- or chisel-blade screwdriver into a slot of the switch and rotation thereof to break a frangible restraint, thus closing the switch and activating the detector. Until activation, the frangible switch impedes mounting of the detector to its bracket; the bracket serving no other function than to secure the detector (proper) to a surface. Upon reaching the end of its useful life, the detector is removed from its bracket and a screwdriver is again used to rotate the aforesaid switch to a battery “drain” position in which a second switch may be actuated to drain the battery. Thereafter the unit is discarded. This disclosure is silent regarding whether the switch is capable of retrograde motion that would allow the unit&#39;s deactivation for removal, storage and later movement to alternate locations; in the (disclosed) alternate embodiments, retrograde motion is foreclosed. 
     In another disclosure, U.S. Pat. No. 5,793,295, providing a DETECTION APPARATUS AND METHOD, an operational switching mechanism for a gas sensor is shown that uses a key member to house a battery package, but does not entertain a circuit-inclusive battery feature. The key, when inserted, activates the circuit irrespective of the installation status of the sensor; thus giving rise to a severe impediment to satisfying the aforesaid quiescent, battery-installed feature that is desired by the instant inventor. 
     An EXTENDED LIFE SMOKE DETECTOR, as disclosed in U.S. Pat. No. 5,444,434, avoids use of a physical on/off switch. The avoidance of the switch, according to the purpose stated therein, is to preclude mishaps that can occur due to improper or negligent usage. The patentee&#39;s objectives are met by constructing the device in an incipiently operative mode, providing extended long- life batteries (up to 12 years use) and avoiding the likelihood of accidental or negligent disablement, by withholding the switch/shutoff means. In the preferred embodiment, the batteries are factory-soldered into the circuitry and the external cover is permanently fixed to the (operative) detector. 
     Earlier hazard detectors were provided a switching that, although distinctive from the form in the instant invention, nevertheless allowed disablement of a part of their circuitry. Such a device is shown in U.S. Pat. No. 4,313,110, entitled: SMOKE ALARM HAVING TEMPORARY DISABLING FEATURES. In this application of the art, battery power is selectively applied to, or removed from, only portions of the device&#39;s circuitry, in order to temporarily silence the alarm signal. However, power continues to be furnished to the critical areas, assuring automatic alarm (enabling) should a hazard occur. An operational mode is originally acquired when the batteries are connected, irrespective of when the device is installed. In similar fashion, U.S. Pat. No. 4,389,635, for INTERFACING ATTACHMENT FOR REMOTE MECHANICAL FIRE ALARMS discloses a switch that is part of a relay system. The switch function is magnetically induced and can be inhibited by interposition of a shield (magnetic spoiler). Tripping of the (local) fire alarm, which is an essentially mechanical activity, results in driving a lever that withdraws the shield from between the switch and a proximate magnet, thus closing the switch and activating a remote alarm circuit. 
     Three of the previously discussed U.S. Pats. Nos. 5,578,996, no. 5,793,295 and No. 5,444,434, particularly the figures therein, are incorporated by reference for their showing of current state-of-the-art. 
     DEFINITIONS 
     The following terms shall have the indicated meanings, as may be further defined throughout this specification: 
     bridge(ing)—is synonymous with short(ing) and means an electrical connection(ing) between two or more set-apart contacts or circuit portions; 
     connect(able)—is synonymous with mate(able) and join(able), in all verb tenses, and means a union of two or more parts, portions or members in(to) the complete fashion or mode for which they are designed, such as, for example, providing electrical continuity between two or more contacts; 
     complement—is the quantity remaining after a part or portion is removed or separated from a unit or a whole, and is both definite and discrete; 
     contact(s)—is one (or more) point(s) of an electric circuit that expose a conductor; 
     device—refers generally to something devised or constructed, but may be a design or pattern, depending on contextual usage; 
     drive(er)—refers to an article, part, etc., or force that effects a motion or state; 
     interleave—means to insert or set between a leaf, flap or tab and used herein to describe certain bayonet-type connections in apparatus; 
     interrupt(ion)—is a gap in, or the act or state of breaking or opening a circuit; 
     separable—indicates that a whole is divisible into two or more non-operative parts; 
     spring-biasing—means using any resilient article to retain/return to a position; and 
     unmate(d)(ing)—are grammatically incorrect, but will be used throughout to mean de-mate(d)(ing), because these word(s) define a single-step activity, as opposed to a two-step mate(d)(ing) activity. 
     All other terms of art shall have their conventional meanings or will be defined, parenthetically, with their usage. 
     BRIEF SUMMARY OF THE INVENTION 
     The instant invention overcomes deficiencies in the prior art by providing to a device, a hazard detector, an on/off switching mechanism that has a physical multiple use (multiuse) capability, i.e., it can be used, repeatedly, to activate/deactivate an electrical circuit. This on/off switch, distinctive from the types commonly used in contemporary hazard devices/sensors/detectors, is made functional only upon the mating of two or more separable portions of such a device. Until the switch is activated, the device, which contains batteries and is otherwise ready to be energized, is quiescent. 
     According to the invention, one (major) portion of the device or detector (hereinafter, “sensor” shall apply only to a specific element) contains essentially all the operative circuitry, power source, and sensor elements, including its protective cover. Within the circuitry an interrupt is provided consisting of a simple, single-point break embodied by two exposed, set-apart conductive points on a circuit board that contains and supports the aforesaid circuitry, power source, and sensor elements. The major portion is designed for contact and mating with its complement, the primary functions of the latter being to serve as a surface-mountable bracket and to securely retain the major portion. The mating, which is achieved by both contact and rotation (two steps) of the device&#39;s two mentioned portions, securely engages at least two mutually-borne, interleaving tabs, or captures two or more bayonet connectors, and effects simultaneous switch activation. This facility advantageously assures that the device is not electrically activated until its two major portions are mated consistent with proper installation. Another advantage of this construction is that it nominally prevents the device from being inadvertently mounted in a deactivated state once properly installed. An unmating, by counter-rotating the major portion (one step) will immediately cause the switch to open. Thus, the switch is activated only when the major portion and its complement are mated. The installed device is deactivated merely by applying a single counter rotation motion to its protective cover. 
     The switch mechanism includes a shorting element and is spring-biased in a position apart from the aforesaid interrupt, and a mating of the two portions of the device urges the shorting element into contact with it. In another embodiment, the interrupt is spring-biased to extend to a prospective shorting strip location that is attained by the strip only upon full mating of the aforementioned portions. In another embodiment, the switch mechanism includes a conductive key. The device is activated only upon inserting the key fully into the device, thereby electrically connecting two or more contact springs. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view, taken from above, of a hazard device including the invention in a first embodiment; 
     FIG. 2 is a sectional elevation of the FIG. 1 device illustrating a mating apparatus between two portions thereof, the covered base and the mounting bracket; 
     FIG. 3 is a sectional elevation of the FIG. 1 device showing the invention, in a first embodiment, immediately prior to its activation; 
     FIG. 4 is the FIG. 3 illustration showing the invention activated; 
     FIG. 5 is an exploded perspective view, taken from above, of a hazard device containing the invention in a second embodiment; 
     FIG. 6 is a sectional elevation of the FIG. 5 device, without cover, showing the second embodiment, immediately prior to its activation; 
     FIG. 7 is the FIG. 6 illustration, with cover, showing the invention activated; 
     FIG. 8 is an exploded perspective view, taken from below, of three component sections of a hazard device and in which a third embodiment of the invention is illustrated; 
     FIG. 9 is a sectional elevation of the FIG. 8 device to showing the third embodiment, immediately prior to its activation; 
     FIG. 10 is the FIG. 9 illustration, with cover, showing the invention activated; 
     FIG. 11 is an exploded perspective view, taken from above, of a hazard device including the invention in a fourth embodiment; 
     FIG. 12 is an expanded view showing one possible arrangement of the contact springs on the circuit board; 
     FIG. 13 is a perspective view of the activation key shown in FIG. 11; 
     FIG. 14 is a top view of the activation key of FIG. 13; 
     FIG. 15 is a sectional elevation showing the engagement of activation key locking tabs in the fourth embodiment of this invention; 
     FIG. 16 is an expanded sectional elevation showing the activation key of the fourth embodiment in the off (deactivated) position; 
     FIG. 17 is an expanded sectional elevation showing the activation key of the fourth embodiment in the on (activated) position; 
     FIG. 18 is an expanded sectional elevation showing the activation key of fourth embodiment in the on (activated) position and showing the device fully mounted to the mounting bracket; 
     FIG. 19 is an perspective view of an optional activation key for a variation of the fourth embodiment; and 
     FIG. 20 is an expanded sectional view showing the activation key of FIG. 19 in the off position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Throughout this description, many detector elements known in the art may not be shown, itemized or discussed. For this reason, and after detailed disclosure of various embodiments, only variations (versions) of the invention switch mechanism will be highlighted. 
     Having reference to the drawings, there is shown in FIG. 1 a hazard detector  10 , typical of the type for which the invention is designed and including a mounting bracket  12 , a base  14 , an essentially electronics/power/sensor (EPS) section  16  and a protective cover  18 . The EPS section  16 , for the purpose of this disclosure, contains fundamentally all of the necessary circuitry (not shown) that would be typical of the particular hazard detector. This circuitry is disposed in a circuit board  20 , which also is adapted to secure batteries  22  thereto. An interrupt  24  is provided in the circuitry as a single-point break in continuity and defined, in an exemplary embodiment, by electrically conductive points, referred to herein as contact pads  26 . Contact pads  26  are exposed on the underside of board  20  and, although not necessary (as will be discussed later), in close proximity to each other. Board  20  is fashioned for capture in base  14  and may be guided by insertion of a standoff  30  into a guide hole  28  (additional guiding elements not shown) so that the interrupt is directly over shorting element  32  held in base  14 . 
     Base  14  features a “living” hinge  34 , on which a shorting element  32  is disposed. Hinge  34  is, in its simplest form, a flap portion of the base which, when deflected from its “idle” coplanar posture in the base, and not constrained in some manner, will be rebiased to that posture, in a spring-like manner (spring-biasing). Remaining aspects of base  14  include two downwardly-depending leaves or tabs  36  that may be set diametrically apart from each other. Tabs  36  may be designed to interleave with, and mutually capture, their upwardly-oriented, like tabs  37  of bracket  12 , thus effecting a mating of base  14  and bracket  12  after CW rotation of one with respect to the other. Final to this figure, and unique to this version, are two ramp-like detents  38  that may be disposed on bracket  12 , 180 degrees apart in top view projecting upwardly from a position that, upon the aforesaid mating and not before, will push the tip of hinge  34  upward and force shorting element  32  to bridge the gap between (contact) pads  26  of interrupt  24 . Thus, when base  14  is aligned with and guided into bracket  12 , and mated so as to interleave tab pairs  36 , 37 , the two portions (EPS-base and its bracket) complete the operative unit. 
     For the most part, FIG. 2, like FIG. 1, depicts structure that is common to three disclosed embodiments of the invention; it is presented to illustrate the mated condition of two portions of a detector that features the instant invention. These two portions of detector  10  include: the EPS-base  40 , containing the fixed circuit board  16 , installed in base  14 , with its projecting tab(s)  36 ; and the mating complement  42 , including bracket  12  with its like tab(s)  37 . In the mated condition, tab  37  is bayonet-fitted into the position indicated, which depending upon the actual mode of manufacture, may be interleaved. The remaining figures deal with the remaining versions of the invention, which are said to be generic, in that all prescribe a form of interrupt(ion) to an otherwise power-enabled circuit and a shorting element that is urged into bridging the interrupt, to activate the host device. 
     FIG. 3 shows, in sectional elevation, EPS-base  40  portion poised over complement  42 . The tip of hinge  34  bears thereon shorting element  32  which is below the board, but offset from interrupt  24  (not visible) because, as indicated by the separation S, the portions have not yet been mated by the action of contact-and-rotation, as previously described. In FIG. 4, mating has been accomplished and detent  38  has been rotated under, and has contacted the tip of hinge  34 , urging shorting element  32  thereon into contact with board  16 -postured interrupt  24  (not visible, but coarsely illustrated in phantom), on the underside of circuit board  20  (see FIG.  1 ). As shown, continuity is restored to the circuit and the device is active electrically. When portions  40 , 42  are unmated, by a mere rotation counter to that of the installation mating, detent  38  is moved away from the tip of hinge  34  and it relaxes, or is spring-like rebiased to its idle (non deflective) normative posture, and the circuit is broken. 
     A second embodiment maybe realized using the first mating activation mode or by physically altering the shorting element mount and avoiding the detent member altogether. FIGS. 5-7 exemplify this version. Interrupt  24 , although shaped differently when compared to the embodiment discussed hereinabove, and using a closer pad array  27 , is substantially identical electrically to the first embodiment. This distinction in (version(s) of) the invention lies specifically in the details for shorting/bridging interrupt  24 , which in this embodiment is accomplished using the shorting element  32 , the spring loaded shaft  33  held in capsule  35 , and the detent-effecting action of aperture  39 . This embodiment derives from the production mode requirements of the fabricator, whether to make a very short shaft (not shown) and detent  38  arrangement, as shown in FIGS. 1,  3 , and  4 , or the alternate shown in FIGS. 5-7. In either case, it is a surface, or part of bracket  12  that invariably urges a bridge-carrying member towards the interrupt, but only upon mating of portions  40  and  42 . This distinction is readily appreciated by reference to FIGS. 6 and 7, which depict a device that is otherwise substantially the same, in most details and operation as FIGS. 3 and 4. The interrupt is not shown but, as it appeared in FIG. 5, it is placed permanently over the shaft  33 -borne shorting element  32 . A capsule  35  contains shaft  33 , which is positioned and spring  29 -biased in a lowered/idle (with respect to interrupt pad array  727 ) state. FIG. 6 specifically details the installation pre-mating setup: portion  40  is placed over portion  42 ; the tabs are in alignment TA; and, shorting element  32  is away from the interrupt. In the mated state M of FIG. 7, after the portions have been pressed together and rotated, the bayonet-connection tabs are interleaved and the shaft  33 , having ridden “up” onto a surface of the bracket  12 , has urged the shorting member  32  into bridging contact with the interrupt pads  27 . Reversal of this rotation step repositions shaft  33  and spring  29  will re-bias it to the lowered, idle posture. 
     In a third embodiment of the switch, shown in FIGS. 8-10, only the physical details of the switch and the interrupt change, but the electrical function remains nominally the same in response to the mating process and counter-rotating step. FIG. 8, showing various components of the device, portrays EPS section  16  subtending a pair of set-apart, downwardly spring-biased pins  41  that are below-the-board extensions of interrupt  24  contacts (not shown) and which correspond electrically to the circuit break of the first and second embodiment. Base  14  has normal bayonet-connection tab  36  setup and a slot  42 , which allows passage of the pins through to it. Bracket  12  has the complementary bayonet-connection tab  37  arrangement and a conductive strip  44  on its upper surface. This strip is of a shape and a position such that alignment of portions  40 , 42  and their contact will allow, at most, only one of pins  41  to contact strip  44 , thus the break in the circuit is maintained. FIG. 9 shows the tab alignment TA and pins  41  in fully extended position. Conductive strip  44  is offset and is not in contact with pins  41 . Reference to FIG. 10 discloses portions  40 , 42  mated M and both pins contacting the shorting strip to effect a closed circuit. Counter-rotation of one of the portions will break the circuit, as in the first and second versions. Those of ordinary skill will realize that the spring-biased pins may be of different design, e.g., including downwardly directed, conductive leaves or tabs. 
     A fourth embodiment, shown in FIGS. 11-20, is similar to the three previous embodiments in that it includes mounting bracket  12 , base  14 , EPS section  16 , protective cover  18  and a switch that is used to activate the device (i.e. make a connection with electrical power). This embodiment also differs from those described above. FIG. 11 shows activation key  60  (discussed in greater detail hereinbelow) and four spring contacts  82  mounted directly on printed circuit board  20 . For pictorial clarity and for the purpose of highlighting the functionality of the switch, printed circuit board  20  does not show most components which are not associated with the switch. 
     Printed circuit board  20  includes, among other electronic components, one or more (at least two is preferable) pairs of spring contacts  82  linked in parallel so that when at least one pair is bridged by activation key  60  (i.e. electrically closed or shorted), the device (hazard detector  10 ) is activated. Multiple spring contacts  82  may be soldered directly to circuit board  20 , and are superposed with a slot  84  in circuit board  20 . Slot  84  is shaped approximately the same as the cross sectional shape of a conductive member (i.e., key  60 ) that may be inserted through slot  84  from the bottom side of board  20  to activate the device. Each pair of spring contacts  82  may include one contact disposed on one side of slot  84  and another contact on the opposite side of slot  84 . As mentioned hereinabove, utilization of multiple pairs linked electrically in parallel with one another, is preferred to improve reliability of the device. An enlarged view of spring contacts  82 , arranged in a staggered pattern, is shown in FIG.  12 . Staggered contacts  82  both enable adjustment of the force required to insert activation key  60  between the contacts and to simplify the process of soldering spring contacts  82  to circuit board  20 . 
     Activation key  60 , which is shown in more detail in FIGS. 13-14, is made of, or coated with, a conductive material. A spring tempered brass or other metal is preferred. During production, once the hazard detector of this embodiment has been substantially fully assembled (snapped together) the loose (i.e. not attached to anything) activation key  60  is inserted into activator slot in base  14  from the side opposite to circuit board  20  (as shown in FIG.  11 ). Activation key  60  is to be inserted fully, i.e., until its horizontal bottom ledge  68  is flush with the bottom surface of base  14 , for electrical testing of the device. Activation key  60  is then pulled away (i.e. retracted) from the board, its undesirable complete removal from the device being prevented by means of the two locking tabs  66  which, upon pulling key  60  away from base  14 , make barb or fluke-like contact with the upper surface of an activation key guide  72  (FIGS. 11 &amp; 15) molded or otherwise disposed on base  14  (see FIG.  15 ). Aforementioned locking tabs  66  prevent accidental removal or separation of activation key  60  from the device, thus eliminating the possibility of its being lost. 
     FIGS. 13,  14 , and  16  show a single dimple  62  on the centerline of activation key  60 . The role of dimple  62  is to provide a sudden surge of resistance when pushing key  60  into base  14 . When in the process of inserting key  60 , the first onset of resistance indicates that locking tabs  66  are partially deflected, and that key  60  is still in the off position. Pushing key  60  further, beyond the off position, requires higher force owing to friction between activator dimple  62  and the corresponding base guide wall  74 , wedging the leading edge of key  60  between spring contacts  82  in order to deflect them for making a reliable electrical connection, and deflection of key  60  in the dimple area when dimple  62  is depressed by guide wall  74  (FIGS.  16  and  17 ). 
     Turning back to FIG. 16, the device is shown with key  60  in the off position. As shown, key  60  is not in contact with spring contacts  82  and dimple  62  is not yet in contact with guide wall  74 . A feature of this embodiment is that it provides a safeguard against installing the device without activating it. When key  20  is in the off position, bottom ledge  68  protrudes from base  14 , where it interferes with making the bayonet-type connection between base  14  and mounting bracket  12 . Only when key  20  is pushed in all the way (i.e. to the ON position), as shown in FIG. 17, may one attach the device to mounting bracket  12 , as shown in FIG.  18 . 
     FIGS. 17-18 are cross sectional views of the device with key  60  in the ON position. Key  60 , as shown, resides among, in electrical contact with, spring contacts  82 . Further, dimple  62  is wedged into guide wall  74  resulting in a slightly “off-plumb” orientation of the main body of key  60 . 
     Owing to the force required to insert activation key  60  into contact springs  82  (which are located on circuit board  20 ), it may be desirable to modify the means by which circuit board  20  is mounted into base  14 . For example, it may be desired to rigidly affix circuit board  20  to base  14  near slot  84  to prevent deflection of circuit board  20  during insertion of key  60 . Optionally, protective cover  18  may be fitted with one or more ribs (not shown) that extend to the upper surface of circuit board  20  when protective cover  18  is snapped into place. The purpose of such ribs is to hold circuit board  20  down securely in place, such that it is not deflected by the force required to insert activation key  60 . 
     Activation key  60  may have a different shape than that disclosed above. For example, FIG. 19 shows one of many optional keys  60 ′ shaped for a corresponding base that may guide this key  60 ′ through a slotted circuit board  20  into contact with one or more pairs of spring contacts  82 . Two notches  61 ,  63  on each side of activation key  60 ′ provide two distinctive positions for the inserted key; the two upper notches  63  corresponding to the OFF position and the two lower notches  61  corresponding to the ON position when the activator is mated with two molded-in snaps  77  (FIG. 20) in base  14 . FIG. 20 shows the activation key  60 ′ of FIG. 19 inserted into the device in the OFF position. Activation key  60  may further include one or more (two shown) locking tabs  66 ′. 
     One of ordinary skill in the art will recognized that numerous other key shapes may be utilized in the present embodiment. For example, a round (solid or tubular) key with slots, such as those shown in FIG. 19, or snaps may be used. The activation key in front view may also resemble an uppercase letter T, with two tab protrusions (see FIG. 19) limiting the key&#39;s travel when pulling it out. Also, instead of pushing an activator in, one can envision screwing in or twisting in a round activation key into two or three flat cross section leaf springs spaced 180 or 120 degrees apart as seen in a view normal to the PCB surface. The above described bridging mechanism and optional variations thereof involve pushing in or screwing in a conductive activator between two or more spring contacts in order to close the circuit to the hazard detector. One may further conceive of a non-conductive activator that is V-shaped, U-shaped, channel or cap shaped that can be pushed onto two or more spring contacts in order to force them together, thereby closing the electrical circuit. 
     The embodiment described hereinabove is for a hazard detector wherein circuit board  20  has copper lamination for electronics on only one side (primarily for cost constraints). Modifications to activator key  60  or other components of the invention to accommodate a double-sided circuit board are well within the scope of this invention. 
     All of the disclosed versions of the invention embrace similar concepts of design and, in structure, are fundamentally the same, namely: an open-circuited, but otherwise operative electronic device, is maintained inactive under non-operational conditions such as transportation, storage, point-of-sale display, etc. Full activity of the device is acquired upon its mating with its complementary portion, which effects and/or requires a closing of the open circuit. The nuance of a shorting strip or element fixed to a driven support may be avoided by simply substituting a conductive support; but such minor modifications may be made without departing from the spirit of the invention.