Method for clearing unlocking key codes in an electronic locking device

A method for clearing unlocking key codes in an electronic locking device in which the unlocking circuit is arranged to be actuated when the code of a magnetic card read by the card reader agrees with an unlocking key code set in the memory, the method comprising using a first clearing card which will function only when the door associated with the locking device is open and a second clearing card which will function only when the door is closed, setting the codes of the first and second clearing cards in specified separate addresses in the memory in the code setting mode for setting the codes of the clearing cards in the processing unit (CPU) of the electronic locking device, determining whether the door is open or closed in the normal operation mode of the CPU, and clearing the unlocking key codes only when the code read by the card reader is identical to the code of the first clearing card set in the above-mentioned manner and the door is open, or when the code read by the card reader is identical to the code of the second clearing card set in the above-mentioned manner and the door is closed.

This invention relates to a method for clearing unlocking key codes from an 
electronic locking device. 
BACKGROUND TO THE INVENTION 
In comparison with mechanical locking devices, electronic locking devices, 
in which the unlocking circuit is arranged to be actuated when the code of 
a magnetic card read by the card reader agrees with an unlocking key code 
set in the memory, have large merits in security and are widely used in 
facilities where a large number of locking devices are required such as 
hotels. 
Such electronic locking devices installed in guest rooms of hotels require 
alteration of the unlocking key code of a room whenever a guest changes. 
If such clearing of key codes could be effected by anyone at any time, the 
electronic locking devices would become useless. 
It is, therefore, necessary to arrange the electronic locking device so 
that the unlocking codes are cleared only when certain conditions are met. 
To be more specific, when a card (hereinafter called a clearing card) 
storing a certain code is inserted into the card reader of the electronic 
locking device. In the context of this invention, the term "clearing of 
key codes" is to be construed as enabling the memory under specified 
conditions by cancelling the flag of the memory storing key codes. 
The present invention was made in view of the aforementioned circumstance, 
and it is an objective of the invention to make the clearing of unlocking 
key codes easier while retaining security of normal operation. 
BRIEF SUMMARY OF THE INVENTION 
According to the invention there is provided a method for clearing 
unlocking key codes in an electronic locking device in which the unlocking 
circuit is arranged to be actuated when the code of a magnetic card read 
by the card reader agrees with an unlocking key code set in the memory set 
in the memory, the method comprising using a first clearing card which 
will function only when the door associated with the locking device is 
open and a second clearing card which will function only when the door is 
closed, setting the codes of the first and second clearing cards in 
specified separate addresses in the memory in the code setting mode for 
setting the codes of the clearing cards in the processing unit (CPU) of 
the electronic locking device, determining whether the door is open or 
closed in the normal operation mode of the CPU, and clearing the unlocking 
key codes only when the code read by the card reader is identical to the 
code of the first clearing card set in the above-mentioned manner and the 
door is open, or when the code read by the card reader is identical to the 
code of the second clearing card set in the above-mentioned manner and the 
door is closed. 
One form of electronic locking device which can be unlocked in an emergency 
is described in European Patent Application No. 87304541.3 and reference 
is made to that Application for a full description.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The method for clearing unlocking key codes in this preferred embodiment is 
used in, for instance, an electronic locking device for hotels, such as a 
personal safe for guests as used in a hotel room, and the configuration of 
such an electronic locking device is shown in FIG. 1. 
The device includes a card reader 1 for reading the code from a card having 
a code encoded on a magnetic strip on the card. Most credit and charge 
cards have such a strip and are well known. A first auxiliary memory 2 is 
provided for storing the code read by the card reader 1. The device has a 
second auxiliary memory 3 and a main memory 4 for storing the unlocking 
codes. A display 5 will indicate if the contents of the first auxiliary 
memory 2 have been stored in the main memory 4. A microprocessor (CPU) 6 
is provided for processing signals and controlling an unlocking circuit 7 
for executing unlocking according to the unlocking signal given by the CPU 
6. A multiposition switch 8 is available for manual selection of the 
operation mode of the CPU 6 according to the following positions: 
0 . . . Normal operation mode of the electronic locking device 
1 . . . Global master key setting position; 
2 . . . First floor master key setting position; 
3 . . . Second floor master key setting position; 
4 . . . First area master key setting position; 
5 . . . Second area master key setting position; 
6 . . . Third area master key setting position; 
7 . . . First maid key setting position; 
8 . . . Second maid key setting position; 
A . . . Emergency key setting position; 
B . . . Test key setting position; 
C . . . Double-lock/unlock key setting position; 
D . . . First clearing key setting position; 
E . . . Second clearing key setting position; 
F . . . Third clearing key setting position 
Of these switch positions, the "0" position is the normal operation mode of 
the electronic locking device in which the locking device will be opened 
when the code of a magnetic card read by the card reader 1 agrees with a 
code set in the main memory 4, and setting of guest key codes is also made 
in this switch position. The position from "1" to "F" are for setting keys 
to be kept by hotel employees of the respective positions. Setting of 
codes for the employees keys can be effected by setting the multiposition 
switch 8 in the respective positions allocated to the respective keys, and 
inserting each key, a magnetic card, in the card reader 1 at least twice 
till, for example, the display 5 is lit up by the operation of the CPU 6 
as shown by the flowchart in FIG. 2. 
Of these keys for employees, the keys of "1" to "C" can unlock the locking 
devices at their respective levels by first setting their codes as shown 
above, setting the multiposition switch 8 in the "0" position, and 
inserting the key card into the card reader. 
The first, second and third clearing keys to be set in the switch positions 
D, E and F respectively enable the main memory to store a code or codes of 
a guest key or keys or clear the storage areas of the main memory 4 for 
setting a code or codes of a guest key or keys in the normal operation 
mode (switch position: "0") of the electronic locking device when the door 
is open (when the inner lever on the door is operated), when the door is 
closed, and when the door is either open or closed, respectively. When a 
key card set in one of these switch positions is inserted into the card 
reader 1 in the normal operation mode of the electronic locking device, 
according to, for example, the operation procedure of the flowchart of 
FIG. 3, the CPU 6 will clear the guest key code or codes in the main 
memory 4, and the code of a magnetic card to be inserted in the card 
reader 1 in this mode will be stored in the main memory 4 as an unlocking 
code (unlocking key code) of the guest key. Once a guest key or keys is 
set in the aforementioned manner, the CPU 6 will not allow setting codes 
of any magnetic cards as unlocking codes unless one of the clearing key 
card is inserted into the card reader 1 according to the position (open or 
closed) of the door. It is possible to arrange the electronic locking 
device so that after setting a guest key code or codes as shown above, if 
the door is not opened at least once within the specified time span, the 
code of the first card to be inserted into the card reader 1 after the 
elapse of the time span is set as an unlocking key code. 
As described so far, this invention makes the use of the electronic locking 
device easier while retaining its safety. 
A latitude of modification, change and substitution is intended in the 
foregoing disclosure and in some instances some features of the invention 
will be employed without a corresponding use of other features. 
Accordingly, it is appropriate that the appended claims be construed 
broadly and in a manner consistent with the spirit and scope of the 
invention herein.