"Don't let the door hit you on the way out."

    Where did this expression come from?  The bane of our society, the symbol of a technology entrenched by vested interests.  A sexist ploy, perhaps...

    The door closer!

    As patent attorney, inventor and entrepreneur, Mr. Hoffberg focuses attention on problems that need solving.  One can only hope for success, both technologically and in execution.  Indeed, the peril inherent in this dumb and pervasive market is apparent.

    The problem is, for various reasons, including fire codes, that one wishes that doors remain closed unless in active use.  For interior doors, the door closer issues involve HVAC-induced pressure differentials, door open and close speed, door weight and inertia, and proper damping of the process.  For exterior doors, the issues are compounded by winds, which can impose relatively high forces on the door, due to the large surface area, requiring a high tension holding the door closed.  This can lead to a 30 lb or higher opening force.  This is compounded by the fact that the door starts to close immediately after release, forcing the first person through the door, under polite circumstances, to hold the door open for those following, or risk traffic delays or personal injury.  Fully automated door closers are expensive, require fixed power, sophisticated installation, and may require service.

    Mr. Hoffberg has proposed a solution to this problem, patent pending, which provides an intelligent hold-open for a traditional passive-type door closer.

    A "portal occupancy sensor", such as a passive infrared, active infrared, ultrasonic, radar, imaging, or pressure mat, detects a person in the vestibule, and holds the door open until he or she passes.  The closing process is generally consistent with past practices, that is, a spring damped by hydraulic fluid closes the door.  The hold-open thus restrains the door for a limited period, for example by providing a valve which modulates the flow of fluid or a lock which mechanically stops the spring or arm.  The design is fail safe, that is, under failure of the electronic devices, the door closer operates as a traditional unintelligent door closer with negligible risk of either unintended locking the door closed or restraining it open.  Power for the electronics come from a battery or self-contained power source, and therefore no wired power is required. 

    Interested parties can contact Steven M. Hoffberg at (914) 949-3100 to discuss further details of the technology, licensing or strategic partnership.