Patent Application
20140240717
The application pertains to position detectors, such as door or window intrusion sensors. More particularly, the application pertains to such detectors which incorporate a fiber optic element, or other type of light pipe, to return light transmitted from a detector mounted on a movable door or window through a portion of an adjacent non-movable frame to the detector for analysis.
There are two kinds of technology that are widely used in implementing door/window intrusion sensors. One includes a combination of a reed switch with a magnet (mechanical contacts). The other includes a source, an infrared (IR) sensor and a reflector. Unfortunately, each of these methods could be defeated by a person having limited knowledge of the sensors.
Mechanical contacts can be easily defeated from the outside by using an additional magnet to keep the reed switch actuated while the window or door is being opened.
Known intrusion sensors based on IR transmission have constantly transmitted the IR. Such devices may be defeated by shining a light, such as flashlight, at the IR sensor, or using a thin mirror as a reflector to defeat the device.
While disclosed embodiments can take many different forms, specific embodiments thereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles thereof as well as the best mode of practicing same, and is not intended to limit the application or claims to the specific embodiment illustrated.
In one aspect, embodiments hereof include a door, or window detector, mountable on one of a frame, or a door or a window, transmits a coded beam of radiant energy, for example, infrared light toward a second element, such as a door or window or a frame. A fiber optic member can be installed in the second element, such as the adjacent door or window, or frame.
The beam of radiant energy can be transmitted from a source, via the fiber optic member, back to a sensor. The detector and the fiber optic member are in alignment only when the door, or window, is in a predetermined position relative to the adjacent member, such as the respective frame.
For example, if the position to be monitored corresponds to a closed door or window, the detector will receive the returned, coded, beam of radiant energy transmitted via the fiber optic member only when the door or window is closed. If the door or window is moved relative to the frame, the transmission through the fiber optic member will be disrupted and the detector will immediately be able to detect the movement and transmit an alarm indictor to an associated security monitoring system.
In another aspect, the fiber optic member can have either a constant radius, or be tapered and have a variable, increasing or decreasing, radius from input end to output end. A security code can be used to pulse modulate the transmitted light. Alternately, the transmitted light can be modulated by phase shifting, frequency modulation, pulse duration modulation, or the like to increase the security of the transmitted signal. An attacker would have great difficulty, and probably not be able to replicate the transmitted, modulated sequence.
With respect to the figures,
Detector 10 includes a housing 16 which can be attached to a door frame, a window frame, a door or a window without limitation. Housing 16 carries control circuits 18 which could be implemented, at least in part by a programmable processor 18-1 and executable instructions, software, 18-2. The control circuits 18 include an input/output interface 18-3 which can be in wired or wireless communication via a medium W displaced monitoring system M. A plurality of detectors, 10-1 . . . 10-n, corresponding to detector 10 can be in communication with system M.
As discussed above, control circuits 18 can activate drive circuits 20a, via a modulated signal, for example a pulse sequence, to energize emitter, source 20b. Emitter 20b in turn outputs a modulated beam of radiant energy, such as infrared, which is coupled to conduit or light pipe 12 when the housing 16 exhibits a predetermined relationship with the conduit or light pipe 12. For example, when the door is closed against the frame or the window is closed against the frame.
In the above condition, the light beam travels through the conduit 12 and is then coupled to detector 22a, processed by receiving circuits 22b, and then made available to control circuits 18. If the transmission path of the beam is disrupted, by opening the door or window; for example, the control circuits can respond to the loss of radiant energy by forwarding an alarm indicator to the system M.
Those of skill will understand that neither the curvature nor the length of the conduit, or light pipe 12, are limitations hereof. Additionally, it will be understood that a variety of processes to modulate the radiant energy beam output by source, or emitter, 20b come within the spirit and scope hereof
In summary embodiments as in
Further, by using the control circuits 18 to generate and transmit an encrypted data packet such as by randomly varying the pattern of light or by using various types of frequency modulation, the detector 10 can be expected to be more reliable and more difficult to be defeated. Since embodiments hereof exhibit both low cost and low power consumption, they can be powered by a batter 26 and are suitable for wireless door/window applications.
With respect to
It will be understood that the control circuits, and instructions 18-2 can present a time varying modulated sequence of optical signals, to be transmitted by conduit 12 and subsequently received at sensor 22a and analyzed by the control circuits 18. Such time varying modulated signal packets can be expected to provide enhanced security for the detector 10 as well as the other members of the plurality 10-i.
From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope hereof. 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. Further, logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. Other steps may be provided, or steps may be eliminated, from the described flows, and other components may be add to, or removed from the described embodiments.
