Electronic lock with changeable opening code

• US 4,392,133 A
• Filed: 02/05/1981
• Issued: 07/05/1983
• Est. Priority Date: 06/05/1979
• Status: Expired due to Fees

• Current Assignee: Sten T. Lundgren
• Original Assignee: Sten T. Lundgren
• Inventors: Lundgren, Sten T.
• Primary Examiner(s): YUSKO, DONALD
• Application Number:
  US06/233,607
• Time in Patent Office: 880 Days
• Field of Search: 340/825.31, 340/825.56
• US Class Current: 340/5.24
• CPC Class Codes: E05B 49/002 Keys with mechanical characteristics, e.g. notches, perforations, opaque marks
• CPC Class Codes: G07C 9/215 the system having a variable access-code, e.g. varied as a function of time

Abstract

An electronic lock of the type which can receive a plurality of electronic keys is disclosed. Each of the electronic keys has a unique key code associated therewith, one of the keys being a control key, the remaining keys being opening keys. The lock includes a read only memory for storing a control code corresponding to the key code associated with the control key and an erasable memory for storing a set of opening codes. The lock further including a control circuit which compares the key code of each key placed in the lock to both the control code and the opening codes. The control circuit opens the lock when the key code of a key placed in the lock corresponds to any one of the opening codes and changes 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.

Claims

1. An electronic lock of the type which can receive a plurality of electronic keys, each of said electronic keys having a unique key code associated therewith, one of said keys being a control key, the remaining said keys being opening keys, said lock comprising:

(A) a read only memory for storing a control code corresponding to said key code associated with said control key;

(B) an erasable memory for storing a set of opening codes; and

(C) a control circuit which compares the key code of each key placed in said lock to both said control code and said opening codes, said control circuit;

(1) opening said lock when said key code of a key placed in said lock corresponds to any one of said opening codes; and

(2) changing said set of opening codes stored in said erasable memory when said control key and one of said opening keys are sequentially placed in said lock.

2. A lock as claimed in claim 1, wherein said control circuit also opens said lock when said control key is successively placed in said lock a predetermined plurality of times.

3. A lock as claimed in claim 1, wherein the manner in which said control circuit changes said set of opening codes stored in said erasable memory is determined by the number of times said control key is sequentially placed in said lock before one of said opening keys is placed in said lock.

4. A lock as claimed in claim 3, wherein said control circuit:

(A) responds to the sequential placement of said control key in said lock a first predetermined number of times followed by the placement of one of said opening keys in said lock by erasing that opening code stored in said erasable memory which corresponds to said one of said opening keys; and

(B) responds to the sequential placement of said control key in said lock a second predetermined number of times followed by the placement of another one of said opening keys in said lock by adding the opening code corresponding to said another of said opening keys to said set of opening codes stored in said erasable memory.

5. A lock as claimed in claim 4, wherein said control circuit erases all of said opening codes stored in said erasable memory in response to the sequential placement of said control key in said lock a third predetermined number of times.

6. A lock as claimed in any one of claims 1 or 2, wherein said control circuit erases all of said opening codes stored in said erasable memory in response to the sequential placement of said control key into said lock a predetermined number of times.

7. A lock as claimed in claim 1, wherein said erasable memory is a random access memory.

8. A lock as claimed in claim 1, wherein said control circuit includes a first comparison circuit for comparing the key code of each key placed in said lock to said control code and a second comparison circuit for comparing the key code of each key placed in said lock to said opening codes.

9. An electronic lock, comprising:

(A) a plurality of electronic keys, each of said electronic keys having a unique key code associated therewith, one of said keys being a control key, the remaining said keys being opening keys; and

(B) a lock member including;

(1) a read only memory for storing a control code corresponding to said key code associated with said control key;

(2) an erasable memory for storing a set of opening codes; and

(3) a control circuit which compares the key code of each key placed in said lock to both said control code and said opening codes, said control circuit;

(a) opening said lock when said key code of a key placed in said lock corresponds to any one of said opening codes; and

(b) changing said set of opening codes stored in said erasable memory when said control key and one of said opening keys are sequentially placed in said lock.

10. A lock as claimed in claim 9, wherein the manner in which said control circuit changes said set of opening codes stored in said erasable memory is determined by the number of times said control key is sequentially placed in said lock before one of said opening keys is placed in said lock.

11. A lock as claimed in claim 10, wherein said control circuit:

(A) responds to the sequential placement of said control key in said lock a first predetermined number of times followed by the placement of one of said opening keys in said lock by erasing that opening code stored in said erasable memory which corresponds to said one of said opening keys; and

(B) responds to the sequential placement of said control key in said lock a second predetermined number of times followed by the placement of another one of said opening keys in said lock by adding the opening code corresponding to said another of said opening keys to said set of opening codes stored in said erasable memory.

12. A lock as claimed in claim 11, wherein said control circuit erases all of said opening codes stored in said erasable memory in response to the sequential placement of said control key in said lock a third predetermined number of times.

13. A lock as claimed in claim 12, wherein said control circuit opens said lock in response to the sequential placement of said control key in said lock a fourth predetermined number of times.

14. A lock as claimed in any one of claims 9 or 10, wherein said control circuit erases all of said opening codes stored in said erasable memory in response to the sequential placement of said control key into said lock a predetermined number of times.

15. A lock as claimed in claim 9, wherein said erasable memory is a random access memory.

16. A lock as claimed in claim 9, wherein said control circuit includes a first comparison circuit for comparing the key code of each key placed in said lock to said control code and a second comparison circuit for comparing the key code of each key placed in said lock to said opening codes.