Communications: electrical – Continuously variable indicating – With meter reading
Patent
1981-02-05
1983-07-05
Yusko, Donald J.
Communications: electrical
Continuously variable indicating
With meter reading
34082556, H04Q 900, E05B 4100
Patent
active
043921337
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates generally to an electronic lock comprising at least one key member with a code identifying said member, and a lock member having means for storing opening codes authorizing the opening of the lock, and for comparison of a code received from a key member with each of the stored opening codes.
To open an electronic lock comprising a key member and a lock member it is necessary to transmit from the key member to the lock member information that identifies the key member. This information is hereinafter designated the key code. If the code transmitted from a key member is found, when checked, to be correct, the lock is opened.
When a key is lost it shall preferably be possible to replace it with a new key having key code other than the lost one. At the same time the code of the lost key must no longer be accepted by the lock member.
It has already been suggested to use in electronic locks keys having two codes which are elements of a consecutive series such that the second code of a key is the first code of the next key, etc. If at least one code of a lost key is known, a new key can be made. See for example U.S. Patent Re. 29,259.
BRIEF DESCRIPTION OF THE INVENTION
The object of the present invention is to provide an electronic lock which in addition to the above-mentioned ability also makes it possible to select any new code which will open the lock.
This and further objects of the invention are realized in that the electronic lock of the present invention is of the type which can receive a plurality of electronic keys, each electronic key having a unique key code associated therewith, one of the keys being a control key, the remaining keys being opening keys, the lock comprising:
(A) a read only memory for storing a control code corresponding to the key code associated with the control key;
(B) an erasable memory for storing a set of opening codes;
(C) a control circuit which compares the key code of each key placed in the lock to both the control code and the opening codes, said control circuit:
(1) opening the lock when the key code of a key placed in the lock corresponds to any one of the opening codes; and
(2) changing the set of opening codes stored in the erasable memory when the control key and one of the opening keys are sequentially placed in the lock.
BRIEF DESCRIPTION OF THE DRAWING
The accompanying drawing illustrates a block diagram of an embodiment of the lock member of the electronic lock according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawing, a first comparator 1 compares the contents of a programmable read only memory 2 with the output of a shift register 3 and two outputs coupled directly and via a delay element 4, respectively, to a clock input and a reset input of a counter 5 having four outputs. The output of the shift register 3 is also connected to a first input of a second comparator 6, the second input of which is coupled to the read output of a random access memory 7, the read input of which is also connected to the output of the shift register 3. The output of the comparator 6 and the first output (0) of the counter 5 are each connected to one input of an AND gate 8, the output of which is coupled to an input of an OR gate 9. The second input of OR gate 9 is coupled to the fourth output (3) of the counter 5. The read output of the random access memory 7 is also coupled to an input of a third comparator 10, the second input of which is supplied with a code containing all zeros and the output of which is coupled to an input of a second AND gate 11. The second input of the AND gate 11 is coupled to the second output (1) of the counter 5 and the output of the AND gate is connected to the write input of the random access memory 7. The output of the comparator 6 and the third output (2) of the counter 5 are connected each to one input of a third AND gate 12, the output of which is connected to an input of a second OR gate 13, the second input of which is connected to the fourth o
REFERENCES:
patent: 3906447 (1975-09-01), Crafton
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