Abstract:
A contactless ambient condition detection system includes at least one base connectable to a power and signal transmitting cable and a compatible detector. The detector removably engages the base. Electrical energy, from the cable is wirelessly coupled to the detector via the base. The detector is in wireless bidirectional communication with the base. Alarm indicating signals, generated remotely, can be wirelessly coupled, from the cable via the base, to the detector. Locally generated alarms can be wirelessly coupled to the cable. Detectors can be replaced without exposing the installer to AC contacts.

Description:
[0001]    This Utility Application claims the benefit of Provisional Application Ser. No. 60/238,183, filed Oct. 5, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention pertains to systems of wired, interconnected detectors. More particularly, the invention pertains to such systems wherein detectors can be safely and conveniently removed from or coupled to the respective system.  
         BACKGROUND OF THE INVENTION  
         [0003]    Known systems of interconnected detectors usually incorporate three wire cables which provide AC energy to each of the detectors via two of the wires. The third wire is used for signaling. When one detector goes into alarm, it can signal via the third wire, its alarm state to all other detectors in the system. The remaining detectors then go into alarm.  
           [0004]    When detector systems are installed, during construction, after testing the detectors are usually removed for safekeeping. They must then be reinstalled subsequently for occupancy. Known detectors for such systems incorporate a base and a separable head which carries a sensor and control electronics.  
           [0005]    Each base is permanently mounted on a surface, such as a ceiling. In one known system, a three wire cable is connected to three contacts on each base. Each base exhibits three electrical contacts, two for AC and one for signaling.  
           [0006]    Each of the heads can slidably engage a base. Three electrical contacts on a respective head, two for AC and one for signaling, slidably engage corresponding contacts on the base as the head is being installed.  
           [0007]    The presence of contacts on the base and head tends to create installation and maintenance issues. The contacts must be kept clean, not always easy to do during construction, and installation personnel must be able to clean particulate matter from the base as needed prior installing the heads.  
           [0008]    There continues to be a need for electrical signal transfer systems usable with interconnected detectors. Preferably such transfer systems would alleviate at least some of the cleanliness problems of known detector systems. It would also be preferable if such transfer systems did not substantially increase unit costs or create manufacturing complexity.  
         SUMMARY OF THE INVENTION  
         [0009]    Interconnectable detectors each have a base and a sensor carrying head. The bases are each mechanically connected to a common multi-wire cable. The cable carries electrical energy for the detectors.  
           [0010]    Each head releasibly engages a respective base. Electrical energy from the cable is wirelessly transferred between the base and the head.  
           [0011]    No exposed contacts are present on either the base or the head. Problems associated with greasy or dirty contacts are eliminated. Non-contact dirt is also reduced due to smoother and uninterrupted exterior plastic surfaces.  
           [0012]    Removable of a head from a base is carried out without exposing maintenance personnel to voltage carrying contacts. In addition, when a replacement head is coupled to a base, there will be no exposure to such contacts.  
           [0013]    In one embodiment, a base and installed head form a transformer for wireless transfer of power from the base to the head. To improve coupling, one of the base and the head can carry an core. Alternately, capacitive or optical coupling could be used.  
           [0014]    In another embodiment, a signal carrying conductor can be incorporated into the cable. Information carrying signals can be wirelessly and bidirectionally coupled between a base and a head. For example, an alarm indicating signal can be wirelessly coupled from a head that has gone into alarm to the signal carrying conductor and then wirelessly coupled to the rest of the heads in the system. Hence, alarm conditions can be audibly and/or visibly indicated not only at the detector which has gone into alarm but at all of the remaining detectors in the system.  
           [0015]    Detectors in accordance with the present invention should be effective in deterring theft. Once the head has been removed from a base, it becomes inoperative for its intended purpose. As such, theft of detector heads may diminish.  
           [0016]    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. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a block diagram schematic of a detector in accordance with the present invention;  
         [0018]    [0018]FIG. 2 is a diagram of a system of detectors as in FIG. 1;  
         [0019]    [0019]FIG. 3 is a graph of an exemplary power modulation signal usable with the detector of FIG. 1;  
         [0020]    [0020]FIG. 4 is a graph illustrating an exemplary modulation scheme usable with the detector of FIG. 1;  
         [0021]    [0021]FIG. 5 is a graph illustrating a second exemplary modulation scheme usable with the detector of FIG. 1;  
         [0022]    [0022]FIG. 6 is an enlarged, side sectional view illustrating details of the detector of FIG. 1;  
         [0023]    [0023]FIG. 7 is an enlarged, side sectional view of a solid rendering of the detector of FIG. 1;  
         [0024]    [0024]FIG. 8 is a perspective view of a base of a type usable in combination with the detector of FIG. 1; and  
         [0025]    [0025]FIG. 9 is a perspective view of a portion of the detector of FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    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 embodiments illustrated.  
         [0027]    [0027]FIG. 1 illustrates a condition detector  10 -i in accordance with the present invention. Detector  10 -i includes a base  12 -i and an alarm unit, or head  14 -i. The head is removably couplable to the base. Detector  10 -i can be incorporated into a system of the same or similar detectors via a multiple conductor cable C having three or four conductors for example.  
         [0028]    The base  12 -i has a housing  12   a -i which carries an electrical connector for coupling to the cable C. The housing  12   a -i also carries electronic circuitry including a cable interface  12   b -i, control circuitry  12   c -i which could be implemented using a programmed processor, for example a microprocessor. The processor  12   c -i is also coupled to base coupling circuits  12   d -i. The base coupling circuits  12   d -i are in turn coupled to an inductor L 1 .  
         [0029]    The alarm unit  14 -i has a housing  14   a -i which carries one or more condition sensors  14   b -i, such as smoke, gas-for example CO, thermal or any other condition sensor of interest. Outputs from the sensor, or sensors  14   b -i are coupled to control circuits, which could include a processor  14   c -i such as a microprocessor. Processor  14   c -i is in turn coupled to interface circuits  14   c -i. One or more alarm indicating output devices, such as audible or visible alarms  14   d -i are also coupled to processor  14   c -i.  
         [0030]    The interface circuits  14   c -i are in turn coupled to inductor L 2 . Inductors L 1 , L 2  are coupled together to facilitate the transfer of electrical signals therebetween. Coupling can be enhanced by using an iron, ferrite, core M 1 .  
         [0031]    Energy and electrical signals can be transferred between the base  12 -i and head  14 -i without any need for mechanical/electrical connections therebetween. Instead, the coupled inductors L 1 , L 2  implement a wireless energy/signal transfer system. In a preferred mode of operation, discussed in more detail subsequently, base  12   a -i can transfer electrical energy, received from cable C, to alarm unit  14 -i. Modulated information carrying signals can also be transferred between the units.  
         [0032]    [0032]FIG. 2 illustrates a system  20  which includes a plurality of detectors, such as the detector  10 -i. The detectors are interconnected by the cable C, illustrated as a three conductor cable C 1 , C 2 , C 3 . Where one of the detectors, such as  10 - 1  goes into alarm, it generates a local audible, or visible alarm indication. Additionally, via the interconnect conductor C 3 , detector  10 - 1  signals remaining detectors in the system. These in turn go into alarm. These detectors can also indicate that the alarm has been initiated by a remote detector.  
         [0033]    Conductors C 1 , C 2  can be used to provide utility originated AC-type electrical energy to the detectors  10 - 1 , - 2 , . . . -n. One of the advantages of the system  20  is that it can support a wide range of applied AC, for example 120-250 volts AC without any need for circuit changes, jumpers or switches. Hence, installation is easy and convenient. It is also safe to install since there are no exposed contacts between the heads  14 -i and respective bases  12 -i.  
         [0034]    [0034]FIGS. 3, 4 and  5  illustrate a communications protocol usable with the detectors such as the detector  10 -i. As illustrated in FIG. 3 base  12   a -i can convert electrical energy such as AC or DC-type energy, received from cable C to higher frequency, for example 1 MHz signals. These signals in turn can be coupled via inductors L 1 , L 2  to alarm unit  14 -i to supply operating energy. This transfer of operating energy, except as discussed below, can be continuous or intermittent as desired. The unit  14 -i can receive energy whenever it engages the base  12 -i. Hence, energy can be wirelessly coupled between the units.  
         [0035]    [0035]FIG. 4 illustrates one type of modulation usable with detectors such as  10 -i. It will be understood that other types of modulation could be used without departing from the spirit and scope of the present invention. In FIG. 4 the power transferring pulses are interrupted for a number of cycles to indicate a smoke alarm-type condition. Similarly, FIG. 5 illustrates a variation of the process of FIG. 4 to indicate the presence of a gas alarm.  
         [0036]    For example, where a base, such as base  12 -i receives a signal via cable C, that another detector in the system  20  has detected sufficient smoke to go into alarm, the base  12   a -i will modulate the energy transfer signal as illustrated in FIG. 4. This modulation will be detected by processor  14   c -i causing that alarm unit to go into a remotely generated smoke alarm. Similarly, where the base  12   a -i receives a signal, via cable C, of a gas alarm elsewhere in the system, it can modulate the energy transfer signal, as in FIG. 5 to communicate the presence of a gas condition to the alarm unit  14 -i. Unit  14 -i will in turn energize output device  14   d -i so as to indicate the existence of a remotely detected gas condition.  
         [0037]    Where unit  14 -i goes into a local alarm, it can intermittently shunt coil L 2  to indicate the existence of and type of alarm. This will in turn induce a modulated current signal in coil L 1 . Process  12   c -i can detect the type of modulation. The base  12 -i can then alert the remaining detectors in the system to the alarm condition. It will be understood that the exact type of modulation is not a limitation of the invention.  
         [0038]    [0038]FIG. 6, an enlarged, side sectional view of detector  10 -i illustrates base  12   a -i with a head  14 -i coupled thereto. The base  12 -i carries, in housing  12   a -i, a cylindrical protrusion  32   a -i preferably centrally located thereon. The protrusion carries primary coil L 1  which is wound around a ferrite cylinder or core M 1 .  
         [0039]    The head  14 -i exhibits a centrally located cylindrical depression  34   a -i which receives the protrusion  32   a -i when coupled to the base  12 -i. Secondary coil L 2  is carried in an annular region  34   b -i between cylindrical depression  34   a -i and surface  34   c -i. Since the head  14 -i is symmetrical relative to a center line A of base  12 -i, it may be installed on the base  12 -i with any orientation and the coupling between coils L 1  and L 2  will be substantially identical.  
         [0040]    [0040]FIG. 7 a sectional view in perspective illustrates further details of the head  14 -i as coupled to base  12 -i. FIG. 8 is a perspective view of base  12 -i without the head  14 -i coupled thereto. As illustrated in FIG. 8, the housing  32   a -i for the coil L 1  and core M 1  is centrally located relative to the axis A. It will be understood that the base  12 -i while preferably cylindrical, is not limited to such shapes. Other shapes can be used without departing from the spirit and scope of the present invention.  
         [0041]    [0041]FIG. 9 illustrates in perspective an exemplary lower portion  34   b -i of the of the housing  14   a -i. As illustrated the housing  14   a -i carries the centrally located protrusion  34   a -i. It will be understood that while an exemplary octagon-shaped head  14 -i has been illustrated, other shapes come within the spirit and shape of the present invention.  
         [0042]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope 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.