Abstract:
A smoke detection and monitoring arrangement detects surreptitious smoking in various zones in a building, e.g., rest rooms and break rooms, and also detects tampering. Each detection unit has an intake grille leading to a duct which contains an air flow detector, a smoke detector and an optical intrusion or tampering detector. Air flow may be induced by an internal fan, or may result from an optional connection to ventilation ductwork. Air flow, smoke, and tamper signals are fed from each unit to a central control panel, which may include visible indicators and an audible alarm.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to smoke detection and alarm systems, and is more specifically directed to a system for detecting presence of smoke, such as tobacco smoke, in one or more zones within a building structure. The invention is also directed to systems that detect and alert to attempts to block air flow through the detection unit or to defeat the detection of smoking. 
   The invention is more particularly directed to a technique for detecting smoke in a confined area, such as a meeting room, bathroom, or conference room, for the purpose of enforcing indoor clean air laws and regulations. 
   Because of concern for the health of workers and customers, many businesses, government offices, and other organizations have taken steps to limit smoking, and thus avoid exposing persons within their offices to second-hand smoke. This concern has also resulted recent government legislation and regulation to promote clean, healthy indoor air, for example, the New York Clean Indoor Air Act. These concerns, coupled with the existence of enforcement provisions and penalties in the clean indoor air legislation, has created a need among employers and business owners for an effective system to detect smoking by company employees, customers, and visitors. This is especially required in small semi-private areas such as rest rooms, lounges, and meeting rooms. 
   Smoke detectors of various designs are common and well known. However, there has been no smoke detector proposed previously that also includes some means for alerting the building staff or business owner if there is an attempt to block the flow of indoor air to the smoke detector, or for providing a discreet alert to a central location if some attempt has been made to disarm the smoke detector, i.e., by simply unplugging it or cutting its signal wires. 
   Prior proposed arrangements for assisting in smoking rules enforcement include a combination smoke detector and flame detector, which may be situated behind the grille of a ventilating air duct, and hidden from view for detecting surreptitious smoking, e.g., in a rest room. One such system is described in U.S. Pat. No. 6,545,608 to Kaufman. A smoking violation detector that may be incorporated into the roof of a portable toilet cabin has been described in U.S. Pat. No. 4,630,037 to Escamilla, Jr. In each case, detection of cigarette smoke by the unit can trigger an audible or visible alarm situated outside the room or area being monitored. 
   However, detection apparatus of the prior art have not concerned themselves with attempts to defeat the smoke detector, and no one has previously incorporated an intrusion or tamper detector, nor has anyone incorporated an airflow detector to alert to the absence of air flow from the monitored zone past the smoke monitor. In addition, the systems of the prior art have not addressed the need for a central monitoring station to continuously monitor the status of the detection units in several different zones within the building structure, nor have they concerned themselves with the need for a central monitoring station to distinguish between various events, such as presence of smoke, tampering, or absence of sufficient air flow affecting operative status of the respective units. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   Accordingly, it is an object of this invention to provide a smoke detection and monitoring system which overcomes the drawbacks of the prior art. 
   It is another object to provide a smoke detection unit that can be installed in a given zone within a building structure, and which also features tamper detection. 
   It is a further object to provide a smoke detection system with tamper detection, with detection units provided in each of several zones within the building and with a central monitor panel that indicates when smoke is detected at each zone, and also indicates detected tampering with a detection unit, e.g., attempting to cover the intake grille to block air flow, as well as indicating operative, in-service status of the units. 
   It is a still further object to provide a smoke detection system which is simple in construction and is easy to install and use. 
   In accordance with one aspect of this invention, a smoke detection and monitoring arrangement is provided to detect and monitor the presence of smoke within one or more zones of a building structure. There are one or more detection units, each being positioned to monitor the air within a respective zone within the structure. Each detection unit includes a duct, an intake grille for admitting air from the zone into said duct, a low-volume smoke detector positioned within the duct, and means inducing an air flow in through said intake grille into said duct. The latter may be a connection conduit that attaches the main duct to an exhaust vent, such as the restroom exhaust, although it is possible to connect it with the building HVAC system. Alternatively, the air flow inducing means may include a small low-volume fan installed in the duct. Preferably, an air flow detector, e.g., a paddle switch, senses air flow or the absence of air flow through the duct. Alternatively, a vane-actuated switch could be used here. There is also an optical tamper detector positioned at the intake of the duct, most preferably at the center of the intake grille. 
   At a monitoring station remote from the zone in question, a main control panel provides visible indication of smoke and of tampering in each said zone being monitored. A communication link connects the detection units with the control panel, and may include wires or wireless communication between the tamper detector, the smoke detector, and flow switch of each said detection unit and the main control panel. 
   In a preferred embodiment, the unit mounts in the ceiling in the rest room, lounge, or other building zone, and can either connect with a general HVAC duct system or simply vent air back into the room. In a preferred example, there is a vent pipe or duct, with a small vent fan, and at the inlet grille there is an optical intrusion detector to detect tampering or blocking of flow of air. This detects a cover, if placed over the grille, and detects items being inserted through the grille, if that occurs. A smoke detecting sensor is mounted within the air flow in the pipe or duct. If smoke enters the vent pipe, the detector senses it, and a small sender associated with the detector signals to the central monitor station elsewhere in the building, and can sound an alarm. There may or may not be a local alarm as well, i.e., to alert the smoker that his or her smoking has been detected. Also, if there is any tampering detected, i.e., by the optical detector, then that also sends a signal to the control panel at the monitor station. A display at the monitor station shows (a) if either smoke or tampering is detected, or both, and (b) the identity or location of the sensor, e.g., second floor women&#39;s bathroom, break room, etc. There may also be an air flow detector that signals if there is blockage of air flow, and whether the fan is working. In some situations it is may also be necessary to control the air pressure within a particular room or compartment, so as to ensure that any air escaping moves is a particular direction, i.e., in or out of the room, and the air flow detection may also provide indication of that status. 
   The above and many other objects, features, and advantages of this invention will become apparent to persons skilled in the art from the ensuing description of a preferred embodiment, which is to be read in conjunction with the accompanying Drawing. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a sectional view of a smoke detection and tamper indicating unit according to one embodiment of this invention. 
       FIG. 2  is a front elevation of control panel of a central monitoring station according to this embodiment. 
       FIG. 3  shows the control panel thereof with its door closed. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to the Drawing, and initially to  FIG. 1  thereof, smoke detection unit  10  in this embodiment is adapted to be mounted in the ceiling of a room, and has a front grille  12  (here, a ceiling grille) that is supported in a frame  14 . In this case, the frame may be a two-foot by two-foot square matching the footprint of a standard ceiling tile, so that it may be fitted into a tile aperture in the gridwork of a standard drop ceiling. Above the grille  12  a duct  16  extends upward. Here the duct  16  may be a tubular duct of six-inch diameter, but the dimensions are not critical. In one option, a small, low-volume fan  18  is mounted at an upper end of the duct  16 , and simply moves air from the zone, i.e., the room below the ceiling, into the space above the ceiling, where it circulates back into the room. In another option, a conduit  20  continues to attach with the exhaust ductwork of the building ventilation system. In either case, a flow of air is induced upwards through the grille and through the duct  16 . Where the fan  18  is employed, a power cord may connect with a source of 110 to 120 volts AC, or a low voltage fan may be used, supplied from a transformer supply (not shown). 
   A low air flow smoke detector  22  is supported on a support web  24  within the duct  16 , so that the detector  22  is centered across the flow axis of the duct. A lightweight paddle  26  is pivotally mounted at one side of the duct beneath the smoke detector  22 , and actuates a microswitch  28  to indicate the presence (or absence) of sufficient air flow. An optical detector  30 , i.e., a photo proximity switch, is mounted within the duct just above the intake grille  12 , and serves to detect tampering, such as the intrusion of objects into the grille, or attempts to block or cover the air intake grille. As shown, an electrical box  32  positioned on the exterior of the duct  16  receives feeds from the smoke detector  22 , the air flow microswitch  28  and the detector  30 , and has an output wire or wiring harness that leads to a central monitoring station where they connect with a control panel  34 , which is shown in FIG.  2 . 
   Similar detection units  10  are installed in each of the zones that need to be monitored, i.e., men&#39;s rest rooms, ladies&#39; rest rooms, employee lounges, etc, for compliance with smoking rules. Each of the detection units would be wired to communicate between its respective zone and the control panel  34 . 
   In this embodiment, the control panel  34  has a lockable front cover  36 , with hinges  38  at the left and a key lock  40  at the right. An authorized building employee may open this with the key to reset the control panel. 
   Various indicating lamps or LEDs are situated on the cover  36 , including a Power ON LED  42 , a set of smoke detection indicator LEDs  44 , one for each zone, a set of tamper indication LEDs  46 , also one for each zone, and a set of service requirement LEDs  48 . Within the control panel  34 , as shown in  FIG. 3 , is a DC printed circuit board  50  containing various electronic components, on which is mounted also one or more reset push buttons  52 , as well as a silence push button  53 , which may only be actuated if the cover  36  is unlocked and opened. A buzzer or sounder  54  is located behind slots or grille openings on the front cover  36 . 
   In the illustrated embodiment, the control panel is designed for three zones, i.e. three detection units  10 . However, there may be more or fewer, depending on the user&#39;s needs. 
   The printed circuit board  50  within the control panel is powered by a standard 110-120 volts. The board will have terminal strips for the three zones (in this embodiment) and a common output. Preferably, the board  50  is mounted on the inside of the cover or door  36  of the panel. The reset switch  52  and silence switch  53  are mounted on the board  50  inside the locked control panel, so that the system will continue to give a smoke detection or tampering indication, or both, for the zone in question until all alarm trips, tamper trips, and service signal have been cleared. Also, inside the control panel is a silence switch, or switches, that will silence all alarms for smoking, tamper, and service. The audible alarm may be constituted by the buzzer sounding constantly for smoke or tamper occurrences, and a broken or intermittent signal for service alarms, e.g., one second of buzzing followed by nine seconds of silence each ten seconds. The signals here may be coded, i.e., one buzz for zone one, two buzzes for zone two, etc. The service requirement LEDs  48  also serve to indicate the operative/inoperative status of the respective detection units  10 , i.e., operability of the smoke detector  22 , the tamper detector  30 , and the flow switch  28 . 
   In the detection units  10 , the smoke detector  22  may include standard three-wire smoke detector, and the air flow detection microswitch  28  may be standard two wire switch. The tamper or intrusion detector  30  may include a two-wire photo proximity detector. 
   The air flow detector  28  gives a positive indication of operation, i.e., ON when there is normal air flow, and will go OFF if air flow is blocked or if the fan  18  fails to function. Alternatively, the fan power, or a rotation detector on the fan  18 , may be employed to sense fan operation. Also, inoperativeness or failure of either the tamper detector  30  or the smoke detector  22  will result in a service signal to the control panel. 
   The smoke detection signal and tamper signal will light the respective Zone  1 , Zone  2 , Zone  3  LEDs  44 ,  46  on the cover. In the embodiment illustrated in  FIG. 2 , the service LEDs  48  are installed on the cover  36 . 
   While wired connections are used here between the detection units  10  and the central monitoring station control panel  34 , a wireless (e.g., radio) or optical system could be employed. 
   The signal should be able to travel distances on the order of five hundred feet or more, without problem in most instances, between the detection units and the control panel. 
   While the invention has been described in detail with respect to a preferred embodiment, it should be recognized that there are many alternative embodiments that would become apparent to persons of skill in the art. Many modifications and variations are possible which would not depart from the scope and spirit of this invention, as defined in the appended claims.