Locks – Operating mechanism – Key
Reexamination Certificate
1999-07-26
2003-02-11
Gall, Lloyd A. (Department: 3676)
Locks
Operating mechanism
Key
C070S342000
Reexamination Certificate
active
06516644
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to master key systems and more particularly to a method of assigning change keys and master keys for a master key system.
One of the most common requests seen on orders for new master key systems is to “provide for maximum expansion”. The customer makes this request to extend the life of the newly purchased master key system. Unfortunately the term “maximum expansion” is completely meaningless. The expansion potential of a key system is defined by the mechanical characteristics of the cylinder. There is no way to configure a system to exceed those characteristics, and there are several ways to allocate the expansion inherent in them. No single expansion configuration is optimal for every facility and none of them will accommodate every possible future event.
The most effective strategy to prevent the early replacement of a key system is to:
Plan it using prudent budgeting techniques.
Implement it using effective project management.
Protect it with sound key control practices.
A system that is not correctly planned and budgeted is doomed to failure from the start. While this first step is essential, it is often shortchanged because the people in the best position to contribute have the least understanding of cylinder mechanics and the mathematics of master keying. To facilitate good planning in the key system design phase, a tool is needed which would allow those people to participate in the process effectively.
Planning tools are paradigms that allow users to understand keying issues without having to understand locks. One such tool is the popular “dividing the key” paradigm. An example of the use of this tool would be to say that in a six pin grand master key system you were using “two pins for masters and four pins for changes.” That would yield (in a traditional Schlage lock style system) 16 masters of 256 changes each. The same expansion could have been allocated differently using, for example, “three pins for masters and three pins for changes” or “one pin for masters and five pins for changes.” Dividing the key is a very useful tool that allows rapid analysis of user requirements. However, it paints in too broad a stroke to be used for complex systems.
The foregoing illustrates limitations known to exist in present master keying systems. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
SUMMARY OF THE INVENTION
In one aspect of the present invention, this is accomplished by providing a method of assigning change keys and master keys in a master key system using a 6 pin cylinder with 5 bittings based on an 8×8 checkerboard and pieces ¼, 1, 4, 16 squares in size representing 16, 64, 256 and 1024 change keys with a master key bitting combination available for each piece which would operate all the change keys assigned to that piece. A first alternate embodiment uses an array of (b−1)
(p−3)
elements (b being the number of bittings and p being the number pins used for master keying), each array element representing (b−1)
3
change keys. The array being repeatedly divided into subarrays of (b−1)
(p−x)
elements, where x=4, 5, 6, . . . , p−1. Instead of assigning the change keys to a checkerboard piece, the change keys are assigned to a subarray representing at least the number of change keys.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.
REFERENCES:
patent: 1100266 (1914-06-01), Sparks
patent: 1122816 (1914-12-01), Teich
patent: 1135027 (1915-04-01), Kohlberger
patent: 1440459 (1923-01-01), Greff
patent: 1590232 (1926-06-01), Fremon
patent: 5000019 (1991-03-01), Foster
Gall Lloyd A.
Michael & Best & Friedrich LLP
Schlage Lock Company
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