Abstract:
A self-powered energy harvesting unit/controller receives motion data from one or more self-powered sensors via low power wire. The energy harvesting unit sends signals wirelessly to a system to perform certain functions as a result of received motion signals or the absence of such motion signals.

Description:
BACKGROUND OF THE INVENTION 
     Several companies, such as Verve Living Systems, have wireless and battery-less motion-sensing products. In addition, there are several companies that provide wired and/or battery-powered motion sensing products. 
     SUMMARY OF THE INVENTION 
     According to the invention, a self-powered energy harvesting sensor/controller receives data from one or more sensors. These several sensing elements are connected to the harvesting unit by a low power cable. 
     According to an embodiment of the invention, the energy harvesting sensor/controller sends signals wirelessly to a system to perform certain functions as a result of received sensed signals or the absence of such signals. 
     Since the multipoint sensing/energy harvesting system of this invention requires no external power to operate, the number of separate sensing units needed for complete spatial coverage is minimized, especially in rooms with complicated geometry or where hardwired power dictates the location of sensors. The energy harvester is placed where light is available. 
     Additional sensing elements can be placed in the optimal locations for best sensing coverage. Since there is no need to keep the harvesting unit close to the sensors, the harvesting unit can be placed in an optimal location, i.e., near a constant source of light like, for instance, a continuously lit exit sign, for more efficient energy harvesting to optimize the performance of harvesting and sensing. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic drawing of the multipoint sensing system of the invention. 
         FIG. 2  is a schematic drawing of a sensor used in the multipoint sensing system shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , a multipoint sensing system of the invention is described herein. The system comprises a solar-powered wireless, battery-less harvesting and sensing unit (“HU”)  10 , a load controller  20 , which controls a load such as an alarm, a lighting system or a communication system with an alarm company or other functions as are known in the art, a plurality of passive infrared sensors (PIR)  50 ,  60  or the like and a battery-less wireless switch  40  that controls the load controller  20 . The PIRs  60  in this example sense motion but one of ordinary skill in the art will recognize that other sensors may be used to sense other parameters. The PIRs are dumb, unaddressed devices and only send the state of the sensing element, e.g., has motion been sensed. Communication in the system is only one-way from the PIR to the HU. 
     The HU  10  has one or more photovoltaic (PV) cells  70  that collect light that is converted to and stored as electrical energy to provide for the operation of controller  65  and to send motion signals to the load controller  20 . One of ordinary skill in the art will recognize that the HU may also be powered by other forms of accessible energy such as heat or microwave energy among other things. 
     The controller  65  in HU  10  manages power collected by the PVs  70 , provides power to and receives signals from the PIRs  50 ,  60  and sends signals to the control unit  20 . The Verve Living Systems Company provides a HU  10 , part number X4110. The HU  10 , as noted above, may also be equipped with a PIR  50  integral therein though it is not always necessary depending on a user&#39;s needs. 
     The load controller  20  may be controlled by a remote manual actuator  40  to turn the load  30  on and off, or perform any other relevant function as may be necessary. Load  30  may be an alarm, a phone signaling device to inform a monitoring company, a lock down system, a lighting system or any other of a plurality of functions. 
     Referring to  FIG. 2 , each PIR  60  has a least one opening  95  for receiving a connector  120  attached to low-voltage cable  100  or  110 . The connectors allow the PIRs to be connected as the constraints of a room require including branched or other shaped arrangement to the HU  10 . 
     In operation, an installer or a user determines what areas of a structure or an environment need to be monitored for motion or other parameter. The PIRs  60  are connected to the HU  10  by means of low voltage cable  100 . Typically, the harvesting unit  10  needs little light. However, the harvesting unit  10  may be placed near a window or other source of light such as exit lights in commercial buildings, or the like. If the HU  10  receives a signal that motion (or other parameter) has been sensed from any of the PIRs  60 , the HU  10  sends a signal to the load controller to actuate the load  30 . 
     Because the system operates with little power, the controller must manage the power sent to the PIRs. In one embodiment, after sensing a parameter such as motion from the PIRs and sending a signal to the load controller  20  to actuate the load  30 , the HU will not send power to the PIRs for a given amount of time. For instance, if the load  30  that is activated is a lighting system, the HU will recharge its system through its cells  70  for a period of time than is less than the period of time that the load  30  (e.g., the lighting system) is programmed to be “on”, thereby giving the HU time to recharge. 
     Because of the efficiency of the system therefore, wire is not required to connect the solar harvesting unit to the load controller  20  or an external power source. Because of the flexibility of the system, the distribution of existing (or, more importantly, non-existing) power outlets to the area to be monitored may be ignored. The sensors  50 ,  60  may then be arrayed in many different areas to create ideal monitoring patterns. If additional sensors are required, other sensors may be daisy-chained to the system by the convenient plug-in features  95 ,  120  (see  FIG. 2 ) relating to each PIR  60 . By using a constant supply of energy such as an exit light, the system is very efficient to operate as it needs no additional power. 
     Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. Most applications relate to intrusion/motion alarms but other applications can be imagined, such as a counting system or the like, door obstruction control, sensing a time in which a guard passes through an area, etc. For that reason, the following claims should be studied to determine the true scope and content of this invention.