Battery missing indicator

Abstract: A battery powered condition detecting unit (20) includes first and second battery retaining prongs (24,26) which in the absence of a battery come in contact with a blocking flange (28) on a cover (14) thereby making it impossible to latch the cover to the unit (20). In the presence of a battery, the free ends (24b,26b) of the battery retaining prongs (24,26) are spread apart so that the blocking flange (28) drops, therebetween allowing the cover (14) to be latched to the unit.(20)

Description: Field of the Invention The invention pertains to structures for visually indicating that a battery is missing from a battery powered electrical unit. More particularly, the invention pertains to visual flags usable with battery powered smoke detectors to indicate the absence of a battery. Background of the Invention Smoke detectors are very commonly found today in buildings of all types. Some of these smoke detectors are AC powered. Others are battery powered. Some include a combination of AC power and battery backup power. Battery powered detectors, while very convenient and easy to install, have suffered from the drawback that a user of the building might not realize the unit needed a battery. As such, because there was no indicia of a missing battery, this condition could persist for a substantial period of time to and including the time when a fire strikes the building. At that point in time, the detector would of course not function and not give out the warning it was intended to provide. This problem has been dealt with in at least two different ways in the prior art. In a one known prior art detector the battery is located in a drawer which is radially movable with respect to the base. So long as the battery is positioned in the drawer, the drawer can be freely opened and closed. When the drawer is closed with the battery present, the detector can receive electrical energy from the battery. When the battery is removed from the drawer, the drawer is locked open and cannot be closed. This provides a visual indication of the missing battery. While the drawer approach does provide an acceptable solution to the battery indicator problem from a consumer's point of view, from a manufacturer's point of view, it tends to be rather expensive and complicated. An alternate prior art battery missing indicator has been disclosed in US-A-4 870 395. The indicator is incorporated into a smoke detector which is intended to be removably affixed to a surface mounted bracket. The bracket might be mounted on the ceiling or the wall of a room. In this detector, when no battery is installed in the unit, a movable obstruction member extends out of a portion of the base which is intended to be located adjacent the bracket. The presence of the extending obstruction is intended to make it impossible to couple the detector to the bracket. When a battery is inserted into the base of the detector, the obstructing member is depressed within the base of the detector by the battery. The detector can then be coupled to the bracket. The above solution is of course not usable with detectors which are directly mountable on a surface without a bracket. In spite of prior developments, there continues to be a need for cost-effective and reliable battery missing indicators which can be incorporated into electrical units such as battery powered smoke detectors. In addition, there continues to be a need for a simple apparatus of this type which readily conveys, visually, the missing battery indication to anybody passing through or in the area where the detector is mounted. Summary of the Invention Starting from the above mentioned prior art disclosed in US-A-4 870 395, the present invention is defined in attached claim 1. Preferred embodiments thereof are described in the subclaims. That is, according to the present invention, a condition sensing detector has a base and a cover. The cover may be separate or hinged to the base. A condition sensor, such as a smoke detection apparatus, is carried on the base. A battery can be mounted in the base to provide either primary or backup electrical power to the detector. The battery is clamped to the base by a pair of deflectable, spaced apart battery retaining prongs holding the battery therebetween. The cover carries a blocking member. This member is rigid and can assume a variety of shapes. One possible shape is generally rectangular. One or more latches can be carried on the base and/or the cover, spaced from the prongs and the blocking member. The prongs are oriented, with respect to the blocking member, to engage the blocking member in the absence of a battery, as the cover moves toward the base. In this condition, the cover is blocked from latching to the base. With the battery present, the blocking member does not engage the prongs but passes therebetween and the cover can move against the base. When the cover moves against the base, in the battery present condition, the latch or latches engage and releasably couple the base and cover together. The latches are always operative to couple the cover to the base whether or not the battery is present in the detector. In one embodiment, the detector can be an ionization-type smoke detector. The present invention is not however limited thereto. Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings in which the details of the invention are fully and completely disclosed as a part of this specification. Brief Description of the Figures Figure 1 is a perspective view of a detector unit in accordance with the present invention; Figure 2 is a side view, partly broken away, illustrating structural aspects of the present invention; Figures 3A and 3B are enlarged, partial, schematic end views of a blocking structure in accordance with the present invention illustrating the missing battery and the battery present conditions respectively; Figure 4 is a perspective view of an ionization-type smoke detector in accordance with the present invention; Figure 5 is a side view, partly broken away, of the detector of Figure 4 mounted on a ceiling; and Figures 6A, 6B, and 6C illustrate an alternate embodiment of a unit with a removable cover in accordance with the present invention with each view partly broken away. Detailed Description of the Preferred Embodiments While this invention is susceptible of embodiment in many different forms, there are shown in the drawing and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiment illustrated. Figure 1 illustrates a detector 10 in accordance with the present invention. The detector 10 includes a base 12 with a cover 14. The cover 14 is illustrated in Figure 1 as being attached by hinge 16 to the cover 12. It will be understood that the present invention is not limited to covers which are pivotably or hingedly attached to a base. In the detector 10 is a sensor unit 20. The unit 20 can be any conventional condition sensing detector. Carried on the base 12 are first and second battery retaining members 24 and 26. The detector 10 can be exclusively a battery power detector wherein the associated battery would be positioned between the members 24 and 26. Alternately, the detector 10 can be an AC powered unit with battery backup. In such an instance the battery would also be positioned between the members 24 and 26. Each of the members 24 and 26 is affixed at a first end, respectively 24a and 26a, to the base 12. Each has a free end respectively, 24b and 26b. The members 24 and 26 can be formed of a resilient plastic and be integrally molded with the base 12. Illustrated in Figure 1 is the relative position of the members 24, 26 with respect to one another in the absence of an energizing battery B. In this condition the free ends 24b and 26b have moved relatively toward one another. As discussed in more detail subsequently in the presence of the battery B, the members 24b and 26b move apart from one another. The cover 14 carries a rigid, generally rectangular, blocking member 28. The member 28 is affixed at a first end 28a to the cover 14. The member 28 also has a free edge 28b which is displaced from the cover 14. The member 28 can be integrally molded with the cover 14. The base 12 and cover 14 respectively carry a recess 30 and latch 32. When the pivotably attached cover 14 moves against the base 12, the latch 32 engages in the recess 30. The cover 14 can thus be releasably coupled to the base 12. In normal operation, as illustrated in Figure 2, the base 12 of the unit 10 is to be attached, as is conventional, to a ceiling C. When so mounted if the cover 14 is not latched to the base 12, it will hang open under the influence of gravity as illustrated in phantom at 14a. Figures 3A and 3B illustrate the relationship of the battery retaining members 24 and 26 with respect to the blocking member 28 in the battery missing and the battery present conditions respectively. In the battery missing condition, as illustrated in Figure 3A, the free ends 24b and 26b of the battery retaining members 24 and 26 move inwardly with respect to one another. As the cover 14 moves toward the base 12 the free edge 28b of the blocking member 28 comes into contact with and is blocked by surfaces on the free ends 24b and 26b. As illustrated in the exemplary embodiment of Figure 3A the free ends 24b and 26b carry pointed end areas 24c and 26c. The end areas blockingly engage V-shaped notches 30a and 30b in the member 28. In the missing battery condition as illustrated in Figure 3A, the interference between the end regions 24c and 26c with the V-shaped regions 30a and 30b blocks further movement in the cover 14 toward the base 12. Hence, the latch 32 while operative never engages the latching recess 30. In this condition, as illustrated in Figure 2 the cover 14 hangs open, illustrated in phantom in Figure 14a, thereby indicating that the battery is missing from the unit 10. Figure 3B illustrates the battery present condition wherein the members 24 and 26 have the battery B located therebetween. The free ends 24b and 26b as a result have moved apart from one another. In this condition, the blocking member 28 passes between free ends 24b and 26b permitting the cover 14 to move against the base 12 and latch thereto. As illustrated in Figure 2, with the battery B present, the cover 14 will be closed against and latched to the base 12. It will be understood that while a particular form of free ends 24b and 26b and blocking member 28 have been disclosed, other end regions and blocking members with different shapes still come within the spirit and scope of the present invention. For example, the blocking member 28 could have an uninterrupted or straight free edge without any V-shaped notches such as 30a and 30b therein. The free ends 24b and 26b could terminate in square ends, indicated in phantom in Figure 3B by edges 32a and 32b. Irrespective of the exact shape of the blocking member 28 and the end regions 24b and 26b, so long as the member 28 comes in blocking contact with the end regions 24b and 26b in the absence of the battery B, such variations in shape are within the spirit and scope of the present invention. More particularly, Figure 4 illustrates a smoke detector 40 in accordance with the present invention. The detector 40 has a base 42 and a hingedly mounted cover 44. The base 42 carries a conventional ionization-type detection apparatus generally indicated at 46. Also on the base 42 are first and second battery retaining prongs 48 and 50. The cover 44 carries a blocking flange 52. The cover 44 can be latched to the base 42 by a latch member 54 carried on the base 42 which releasably engages a latch notch 56 carried on the cover 44. As the cover 44 rotates toward the base 42, indicated at 44a, assuming a battery is present, the blocking flange 52 drops between the battery retaining prongs 48 and 50 allowing the latch 54 to engage the latch retaining recess 56 in the cover 44. In the absence of a battery the blocking flange 52 comes into contact with the free ends of the battery retaining members 48 and 50 and the cover 44 is blocked from closing thereby as illustrated generally in Figure 3A. Figure 5 illustrates the detector 40 mounted on a ceiling C as is conventional. In this mounting orientation, the cover 44 will hang open in the absence of a battery providing a visual indication of that absence. With the battery present, the cover 44 can be latched closed against the base 42. The principles of the present invention can be applied to covers which are not rotatably attached to the respective base of an electrical unit. Figures 6A, 6B and 6C illustrate an alternate embodiment 60. The embodiment 60 includes a base 62 which can be affixed to a ceiling or wall surface S. The unit 60 also includes a cover 64. The cover 64 can be latched to the base 62 in the presence of a battery B as illustrated in Figure 6A. However, as illustrated in Figures 6B and 6C, when the battery B is missing from the base 62 the latch members 66a and 66b carried thereon cannot simultaneously engage the cover 64. The engagement is blocked by flange 68 which intersects first and second battery prongs 70a and 70b, of which only 70a is illustrated. The prongs 70a and 70b are the same general type prongs as illustrated previously in Figure 1 as prongs 24 and 26. From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the novel concept of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.

Claims: An apparatus for inhibiting latching of a cover (14; 44; 64) to a base (12; 42; 62) of a battery powered unit in the absence of a battery (B), including a first resilient, elongated battery retaining member (24; 48; 70a), said member having a free end (24b) deflectable in response to the presence of the battery (B); and a latch mechanism (30, 32; 54, 56; 66a, 66b) carried at least in part on one of said base or cover; the apparatus being characterized by a second resilient, elongated battery retaining member (26; 50; 70b), wherein the first and second battery retaining members (24, 26; 48, 50; 70a, 70b) are spaced apart and biased toward one another and carried on one of said base or said cover, said members each have a free, battery retaining end (24b, 26b), said ends being deflectable away from one another in response to the presence of the battery (B); and by a blocking flange (28; 52; 68) carried on the other of said base or said cover, wherein said flange engages at least one of said ends (24b, 26b) in the absence of the battery, thereby inhibiting latching of said cover to said base. An apparatus as in claim 1, with said battery retaining members (24, 26; 48, 50; 70a, 70b) and said blocking flange (28; 52; 68) oriented so that, in the presence of the battery (B), said flange passes between said members. An apparatus as in claim 1 or in claim 2, wherein said blocking flange (28; 52; 68) engages both of said ends (24b, 26b). An apparatus as in claim 1, with said blocking flange (28; 52; 68) having generally rectangular shape and with the cover (14; 44; 64) being closable against the base (12; 42; 62) only in the presence of the battery (B). An apparatus as in claim 4, with a hinge (16) between the cover (14) and the base (12).

Inventors: CONFORTI FRED J, CONFORTI, FRED J.
Applicants: PITTWAY CORP, PITTWAY CORPORATION
Application year: 1990
Main classification: G08B17
IPC codes: G08B17, G08B21, H01M2, G08B29