Note: Descriptions are shown in the official language in which they were submitted.
I
SPECIFICATION
ELECTRONIC LOCK END KEY SYSTEM
FOR HOTELS AND THE LIKE
BACKGROUND OF THE INVENTION
_ _ ___, _
The advantages of electronic lock. systems over
their mechanical counterparts are obvious in that the
electronic lock systems offer greater protection in
yuardlng against unauthorized entry, key duplication and
lock picking. The prior art electronic lock systems,
in general, include an electronic control circuit which.
responds to a coded card, or other coded key, to operate
an electromechanical latch The cards in the prior art
systems are usually coded optically magnetically,
electrostatically, or capacitively.
united States Patent 3,~21,704 discloses an
electronic lock system in which the electronic control
circuit in each door can be readily changed to respond
to new codes. This is an essential requirement in
hotels, in order that each new guest may be issued a
card bearing a new code which will be effective to
open a particular door, and which will cause the card
issued to the previous guest to be no longer effective
in operating the door. A feature in the system de-
scribed in the patent is that when the new guest inserts
his card into the slot in the door of the room assigned
to him, the insertion causes the unit in the door to be
changed to respond to the new code encoded into the card
of -the new guest, and to be no longer responsive to the
code encoded into -the card issued to -the previous guest.
As mentioned in United States Patent 3,~21,704, a
requirement in adapting electronic lock systems to hotels
is the necessity that the lock must be responsive to a
variety of coded cards. For example, a maid must be
provided with a maid's card. For security reasons,
however, it is generally desirable to provide the maid
with a card which will open only the rooms to which the
particular maid is assigned, and no others. super-
visor may be issued a higher level master card which will open a larger number of rooms than the maid's
card, corresponding to the number of rooms assigned to
all maids, under the supervision of the supervisor
Still higher level master cards may be issued to hotel
personnel for opening all doors in a section of the
hotel for maintenance purposes, or in case of fire, or
other emergency. It will be seen, therefore, that the
requirement of a number of levels of cards, and the
recurrent need to change the individual door locks or
groups of door locks to control theft, presents a sub-
staunchly problem in adapting electronic lock systems
to hotels.
In the electronic lock system described in the
aforesaid patent each lock. is controlled by a decoding
device which includes a recitable memory In its
simplest form, the memory is preset Wyeth multi-hi-t
combination. Each. time a card is used in the system
described ion the patent, at least two numbers are
entered into the system, a key number and an authorize-
lion number. If the key number is found to match the combination previously stored in the particular decoding
device, the lock of the corresponding door will be
activated, If such a match is not made, a comparison
is then made between the authorization number on the
I card and an authorization number entered by the previous
user. If the comparison is established the decoding
device is reset to the new key number so -that the lock
may be opened by the new card. Accordingly to change
--3--
a lock combination in any particular decoding device
in any particular door in the system described in the
patent, all that is necessary is to encode a newly
issued card with a new card number and with the last
card authorization number. when, when the new card is
inserted into the particular door the circuitry will
respond to change the stored code to the new code, and
to activate the electromechanical latch system to
open the door
In the system described in the patent, when a
guest registers for a room he is given a card bearing
at least two fields of encoded information. One field
contains the new key number, and the second field con-
twins the authorization number assigned to the last
guest to use the room. Upon the first insertion of
the card by the new guest, the lock is automatically no-
keyed to the new combination encoded into the new card.
Thereafter, until the lock combination is again changed,
the only card number that will open the particular door
2Q is that assigned to the present guest; and no prior
guest cards will open the lock since the decoding
circuit now contains a new code number,
Because the lock combination is stored in a
memory accessible only by a particular logic circuit,
electronic door locks of the type described in the
patent are not susceptible to being picked. Further,
each lock may be rekeyed without toe intervention of
anyone but the user Finally, there is no inter
connection with a central controller from the individ~
vat electronic units in the individual doors, which
saves a considerable amount of installation cost
The electronic lock system ox the present
invention is of the same general type as descried in
I
United States Patent 3,821,704~ However, the electronic
lock system of tune invention has additional features
which include, inter alias the installation in each
door of a battery energized microcomputer controlled
electronic circuit, and which are constructed so
that units of the present invention to be installed
easily and expeditiously in existing hotel doors of
the type having mortise locks or having locks located
in the knobs
lo Each of the units of the invention mounted in
the individual doors responds to a programmable
magnetically coded key card which serves to activate
an electronic lock circuit if the code is proper, and
also to up-date the code stored in the unit it the card
has been issued to a new guest, Each unit, in accord
ante with the concepts of the present invention, is
also capable of identifying and recording the time of
all entries into the room, and of limiting the number
of days the card issued to any particular guest is
effective,
The key cards used in the electronic lock soys-
them of -the invention are magnetically encoded, and they
are reprogrammable and may be. used many tummies Data
on each car is proximity sensed by a non-contact
electromagnetic read head, when the key card is in-
sorted into a slot in any one. ox the electronic lock.
door units, so that the read head does not contact the
magnetic material in the card and the problems of am-
buggies data transfer due. to dust, dirt, grease and the.
like, are eliminated, such problems being common to
the prior art key card reading systems, whether
magnetic strip, optical or capacitance encoding of the
individual cards is used. In addition, the individual
bits on the card used in the system of the invention
are sufficiently loosely packed so that the informal
lion may be written into the card and read from the
card by manual movement of the card without any need
for drive motors or the like..
For convenience, each unit may be constructed
so that the key cards may be inserted into the slot with
either face up. The card may also be programmed with a
guest's identity and sent to the guest when a reserve-
lion is made. Then, upon entering tile hotel, the guest
need merely insert his card into a card reader to
complete check-in and to receive his room assignment.
On Choctaw the guest merely inserts his card into the
reader and his billing information is automatically
recorded and he is provided with a printout
A portable computer is provided which may be
hand carried to any door and plugged into the electronic
control unit in that door to read identification and
time data stored in the unit, and also to reprogram
2Q the door unit if necessary, and to program -the unit.
door for an initial use.
Specifically, the present invention provides
an electronic lock control system to be mounted in a
door including: microcomputer means having first
I binary counter means for storing binary data represent-
live of a first predetermined multi-bit binary number
and second binary counter means for storing binary data
representative of a second predetermined multi-bit bin-
cry number having a predetermined numeral relationship
with said first predetermined multi~bitbinary number; a
key member having multi-bit binary data stored -thereon
corresponding to an entrance code; key reading means
connected to said microcomputer means for reading the
binary data stored on said key member and for intro-
during inputs corresponding to such data into said
I 66239-1157
microcomputer, the entrance code of said key member and the binary
data stored on said first counter means for producing an access
output, and said microcomputer responding to a match between the
entrance code of said key member and the binary data stored in
said second binary counter means for producing said access out-
put; means connected -to said microcomputer and responsive to said
access output to unlock the door; and said microcomputer respond
in to a match between said entrance code stored on said key
member and the binary data stored in said second binary counter
lo for changing the count of said first and second binary counters by
a predetermined amount.
According to another aspect, the invention provides an
electronic lock control system to be mounted in a door including:
microcomputer means having first binary counter means for storing
binary data representative of a first predetermined multi-bit
binary number and second binary counter means for storing binary
data representative of a second predetermined multi-bit binary
number having a predetermined numeral relationship with said
first predetermined multi-bit number; a key member having multi-
bit binary data stored thereon corresponding to an entrance code key reading means connected to said microcomputer means for read-
in the binary data stored on said key member and for introducing
inputs corresponding to such data into said microcomputer, the
entrance code of said key member and the binary data stored on
said first counter means for producing an access output, and
said microcomputer responding to a match between the entrance code
I
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of said key member and the binary data stored in said second
binary counter means for producing said access output; means
connected to said microcomputer and responsive to said access
output to unlock the door; and said microcomputer responding -to a
match between said en-trance code stored on said key member and
the binary data stored in said second binary counter for chanting
the count of said first and second binary counters by a predator-
mined amount.
The present invention also provides a key member for
use with an electronic lock, or the like, comprising a magnetic
card formed of selected magnetizable material, and having a con-
figuration to be magnetized to represent a plurality of binary
bits.
BRIEF DISCRETE N OF THE DRAWINGS
FIGURE 1 is a perspective representation of a door lock
unit which incorporates the concept of the present invention;
FIGURE 2 shows a metallic card which when inserted into
a slot in the door unit of FIGURE 1 serves to unlock the door,
the card being magnetically coded with any selected code by an
appropriate coder located, for example, at the hotel desk;
FIGURE 3 is a schematic representation of the various
components incorporated in the door unit of FIGURE 1, including a
circuit board.;
FIGURE 4 is a circuit diagram of the circuitry on -the
circuit board of FIGURE 4; and
~23~
--7--
FIGURE 5 is a representation of a portable
computer which is used to encode the card of FIGURE 2,
and which may be used to read data stored in the
individual door units, and to program the door units
for original use
DETAILED DESCRIPTION OF TIE ILLUSTRATED EMBODIMENT
The door unit of FIGURE 1 is designated 10,
and it includes a slot 12 into which. a magnetically
encoded card 16 is inserted in-to the slot When the
I card bears the appropriate code, the door is unlocked,
and may be opened by turning a handle 14. The card is
formed, for example, of magnetizable material The
card includes a first series of slots designated A, a
second series of slots designated B, and a third series
of slots designated C. The portions of the card be-
tweet the individual slots are appropriately magnetized
in accordance Wyeth binary code. The series A and
represent data bits, whereas the series C represent
clock bits. The clock. bit slots C may also be used
with an optical reader for clocking purposes if so
desired. For example, when the card is inserted into
swept 102 of FIGURE 5, -the central row of slots may he
read optically for clocking purposes, and when the card
is withdrawn thy clock bits may be read magnetically.
The card may be encoded by a computer 100
(FIGURE 5) by inserting the card in a slot 102, and by
operating the keyboard of the computer. Computer 100
may be a small inexpensive, portable computer, such as
an EPSON HX-20. Tins computer is usually constructed
30. to encode a magnetic tape in a cassette The simple
modification of replacing the cassette by card-
receiving slot 102, enables the card to be encoded by
the computer.
I
The programmable card 16 is advantageous over
optically encoded cards in that it is easily encoded
without any need for a hole punching machine, it is no-
usable, and it is not susceptible to counterfeiting.
As shown in FIGURE 3, appropriate electronics
are contained within the door unit 10 of FIGURE 1,
including a circuit board 20, a board reader 22, a
switch 24, an energizing battery 26, a solenoid 28,
and a privacy septic 30, The card reader 22 includes
three magnetic read heads AYE, 22B, 22C, When card 16
is inserted in slot 12, the card moves under the three
read heads and is moved inwardly until it actuates
switch 24~ Switch 24 activates the circuit, and the
card is read as it is withdrawn from the slot. The
three heads AYE, 22B and 22C of the card reader 22
sense the encoding between the various series of slots
A, B and C on card 16~ The magnetic sensing by the
card reader 22 is on a proximity basis, in that the
read heads AYE, 22B and 22C do not actually contact the
20. magnetic card so that the problems of ambiguous data
transfer due to dust, dirt, grease, and thy like, do
not arise.
The battery 26 activates the circuitry on Syria
cult board 20., and if the particular card 16 bears the
proper code., solenoid 23 will be activated when the card
is withdrawn from the slot, so that the door may be
opened Privacy switch 30 may be actuated when a person
is in the room, so that the circuitry on circuit board
20 will not respond to any card inserted into the slot,
3Q except the emergency card. Battery 26 may be a 2.9 or
3,4 volt lithium battery which has a life expectancy
of years
~3~Z~
The circuit diagram of the door unit is shown
in FIGURE I. As shown, the three read heads AYE, 22B
and 22C which make up the card reader 22 are respectively
connected to comparators Al, A and A which may be
contained in an integrated circuit of the type design
noted LM339. The comparators Al, A and A are connected
to pins PB0, Pal and Pal of a microcomputer MCKEE which
may be of the type designated MC146805G2~ The compare-
ions Al and A supply data bits to the microcomputer
MCKEE, and the comparator A supplies clock bits,
Battery 26 has its negative terminal connected to
a negative lead designated B-, and its positive terminal
connected to a positive lead designated I. The lead
By is connected -to the emitter of a transistor Al, the
collector of which. is connected to a lead designated
. A pair of resistors Al and R2, each having a
value of 5~1 kilo-ohms, are connected in series between
the lead By and By These resistors are shunted my a
.1 mlcrofarad capacitor Of. The junction of resistors
Al and R2 is connected to the read heads AYE, 22B and
22C~ and to a group of 5.7 kilo-ohm resistors R3, I
and R5. The read heads are connected to the inverting
inputs of the. respective comparators Al., A and Air
and the resistors R3, R4 and R5 are connected -to the.
non-lnverting inputs of the comparators, A group of 1
megohms resistors R6, R7 and R8 connect the respective
output terminals of the comparators to the correspond-
in non-lnverting input terminals The lead By is
connected to the comparators to excite the comparators,
and is also connected through respective 100 kilo-ohm
resistors R9, R10 and Roll to pins PB0, Pal and Pal of
microcomputer MCKEE Pins PB2, PB3, PB4, PB5, Ps6 and
PB7 of the microcomputer are grounded,
--10--
The privacy switch 30 is connected to lock case
ground, and to pin PA of the microcomputer MCKEE.
Lead s-, on the other hand, is connected to magnetic
head ground.
The card switch 24 has its armature connected
to pin PA of the microcomputer, and a normally open
terminal connected to lead B-, and a normally closed
terminal connected to a 5 micro farad capacitor C2 and
through a 5~1 kilo-ohm resistor R14 to lead By
Resistor R14 is also connected to pin Vcc of the
microcomputer, and capacitor C2 its connected to lead B-.
Card switch 24 is actuated to one position when the card
is fully inserted in the slot 12, and it is actuated to
its second position when the card is withdrawn from the
slot The microcomputer Mel produces the access output
at PA a predetermined time aster the switch 24 has
keen actuated to its fixate position by the full insertion
of the card into the slot and then returned to its
second position by the withdrawal of the card. The
circuit is activated when the card is Pull inserted,
and the card its read as it is withdrawn
Pin PCQ of the microcomputer is connected -to the
junction of a grounded capacitor C3 and resistor R15,
the resistor being connected to thy positive terminal
of voltage source 26. Pin PA is connected to a clock.
terminal Thor 100 coulomb resistor R16. Pin PA is
connected to a data terminal Thor lQQ.kilo-ohm
resistor R17. Lead B- is connected to a common ground
terminal, as shown. Lead By, on the other hand, is
3 a connected through a diode Curl of the type designated
IONIC, and through a fuse if to a power terminal.
The computer 100 is shown in FIGURE 5, may
normally be kept at the desk of the hotel, or other
facility, and is used to code the guest cards, as each.
I
guest checks into the hotel. This being achieved by in-
sorting a blank card into a slot 102 and then creating
an appropriate code on the card by operation of the keys
of the computer.
Computer lQ0 may be carried to the individual
doors, and then connected to the terminals described
above to read identification and time date stored in
the unit; and also to supply power, clock signals,
data and a ground connection to the circuitry of
FIGURE 4 for originally programming the microcomputer
MCKEE, or for reprogramming the microcomputer in the
event of a synchronization failure, or for opening the
door in the event of battery failure.
A pin designated "OSC out" is connected to a
470 kilo-ohm resistor R20 and to a 22 megohms resistor
R22, resistor R20 being connected to a grounded 22
picofarad capacitor C6 ! and resistor R22 being con-
netted to a pin designated "OSC in'` of microcomputer
MCKEE and to a 70. picofarad grounded capacitor C7,
32~768 KHz crystal Al is connected between the common
junctions of resistor ~22, capacitor C7 and resistor
R20, capacitor C6~
Pin Pal of microcomputer MClQ is connected to a
10 kilo-ohm resistor R2~, and pin PA is connected to a
1 kilo-ohm resistor R26. These resistors are. connected
through respective 5.1 kilo-ohm resistors R28 and R30
to lead B+.
The common junction of resistors R24 and R28 is
connected to the base of a PUP transistor Q2, and the
common junction of resistors R30 and R26 is connected
to the base of a PUP driver transistor Q3. The emitters
of the transistors Q2 and Q3 are connected to the lead
B+. The collector of transistor Q2 is connected through
-12-
a 100 ohm resistor R36 to TED CRY, which is also con-
netted to lead B-. The collector of transistor Q3, on
the other hand, is connected to the lock solenoid S10
which may, or example, be composed of 300 turns of
No. 39 wire, and to diode CRY which is connected to
lead B-. The other side of the lock solenoid S10 is
connected to the lock casing
The junction of fuse if and diode Curl is con-
netted to a 10 kilo-ohm resistor R50 which., in turn, is
connected to a diode Clue the diode being connected to
lead By, The lead By is connected through a diode CRY
to pin PA of the microcomputer and through diode
CRY to the B- lead. Lead B+ is also connected through
a diode CRY f and Thor further diode Cola to the
s- lead, the junction of the latter diodes being con
netted to pin PA of the microcomputer, The diodes CRY,
CRY, CRY and CRY. may ye of the. type designated lN4148.
Diode CRY is shunted by a 4,7 megohms resistor R6Ø
The junction of resistors Al and R2 is connected
20. through a 1 megohms resistor R62 to the non-inverting
input of a comparator A which may also be included in
the integrated circuit containing comparators Al, A and
A. The output terminal of the comparator A is con-
netted to pin PA of microcomputer MCKEE, and through a
100 kilo-ohm resistor R64 to the junction of resistor
R14 and capacitor C2. Resistor R64 is also connected
back through. a 4,7 megohms resistor R66 to the inverting
input of comparator A, and to a 2.2 megohms resistor
68 which is connected to the B- lead, Resistor R64 is
also connected through a 10.0 kilo-ohm resistor R80 to
the junction of resistor R50 and diode CRY
The pin PA of the microcomputer is connected
through a 10. coulomb resistor R82 to the base of
transistor Al ! and through a 5.1 kilo-ohm resistor R84
to the lead B+.
I
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The transistor Al is normally non-conductive, so
that there is no significant drain on the battery 26
when the circuit of FIGURE 4 is not in use. When the
card 16 of FIGURE 2 is inserted into slot 12 of
FIGURE 1, the card switch 24 closes, and this causes the
microcomputer MCKEE to render the -transistor Al con-
ductile, thereby energizing the system. The transistor
Al remains conductive while the card is being withdrawn
from the slot, and until all the bits on the card have
been read, after which. the transistor Al again becomes
nonconductive.
So long as the circuit is activated, the tray-
sister Q2 is intermittently energized and causes the
LED CRY to flash. The flashing continues, for example,
for 5 seconds. If the proper code is on the card, the
pin PA of the microcomputer causes the driver tray-
sister Q3 to become conductive, thereby energizing
solenoid S10 to unlock the door, The door must then be
opened during the 5 seconds while the LED CRY is
20. flashing At the end of 5 seconds, the transistor Q3
is again rendered non-conductive,de~energizing -the
solenoid.
When the privacy swish is closed, lead By is
grounded, and the circuit is ineffective to unlock the
door, even if a properly coded card is inserted into
slot 12 of FIGURE 1..
As described in conjunction with. FIGURE 2, the
rows A and of the magnetic card 16 represent the data
bits, and the center row C represents the clock bits.
I Accordingly, of the total bits which represent the data
code, a certain number are used for the entry code, and
the remaining bits are used fur an identification code..
I
The microcomputer MClO responds to the entry
code on the card to make a comparison with the code
stored in its memory, and if a comparison is achieved,
causes the transistor Q3 to be rendered conductive so
as to energize the door unlocking solenoid Slow The
microcomputer also responds to the identification code
bits to store in its memory, identification data in-
eluding information relating to the time of each entry
and whether the key used was a service key, a maid's
lo key, or a guests key
Specifically! the microcomputer 10 stores five
levels of key codes in a constructed embodiment of the
invention. The first level responds to the insertion
of a guest card in slot 12 of FIGURE l; the second level
responds to the insertion of a maid's card in the slot;
the third level responds to the insertion of a master
card in the slot of FIGURE it a fourth level which
responds -to the insertion of a grand master card in the
slot; and a fifth level responds to the insertion of an
I emergency card into -the slot. The microcomputer MCKEE
also stores a sixth level of key code which corresponds
to an access code for the computer 1~0 of FIGURE 5 when
the computer is carried to the door and plugged into the
circuit of FIGURE 4.
With respect to the guest level, each new guest
is issued a card, and his card will activate but a single
door. With respect to the maid level, each maid is
issued a card, and her card will activate a predetermined
number of doors when the privacy switch has not been
activated The master level cards will for employ
activate all the doors to permit servicing unless the
privacy switch has been activated; whereas the emergency
level cards will activate the doors even though. the
I
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privacy switch 30 has been activated, in order to gain
access to the room under all conditions.
The use of magnetic armature cards means that
the cards may be reprogrammed and used many times, which
reduces card cost, as compared with the single use card.
The data on the card is proximity sensed as mentioned
above, eliminating the need for the reader heads to
touch the card which., as mentioned, eliminates the
problems of ambiguous data transfer due to dust, dirt,
grease, and the other environmental problems common to
electronic readers, whether magnetic strip optical or
capacitance,
As will be described when a new guest is
issued a card for a particular room, the code on his
card is stepped by one or two on the binary scale, as
compared with the previous card Then, when the new
guest inserts his card into the slot, -the door unit
responds to his card to unlock the door, and at the
same time sets a register in the microcomputer 10 so
that the system will no longer respond to the preceding
card. Even though the change of code from one card to
the next in the constructed embodiment of the system is
"1" or "2" on the binary scale, unauthorized entry can
still be prevented by providing no indication on the card
as to the position of -the most significant bit or of the
other bits of lesser significance
As mentioned above, the microcomputer 10 will
read the card and record the time and identity of each
person entering the room, for example, for the last
fourteen entries. Specifically, the microcomputer will
indicate whether the person entering the room was a
guest, a maid, service personnel or emergency personnel
In the case of hotel personnel, each is identified, be-
cause of identification data recorded on their cards.
I By being able to read the card and record the last
~3~2~)~
-16-
fourteen entries, the list of suspects of any burglary,
or the like, is narrowed, which acts as a significant
deterrent to prevent burglary by hotel employees. As
mentioned above, the identification and time data is
read from each unit by the computer of FIGURE 5,
The fact that the code change on the successive
cards is in accordance with a predetermined binary
count, obviates any need for any communication between
the card coding mechanism at the main desk of the hotel
and the various door units. Whenever a new card is to
be issued to a guest, for example, it is merely
necessary to insert a blank. card into slot lQ2 of
computer 100 (FIGURE 5) at the main desk, and to encode
the card with the current binary code corresponding to
a particular room, increased by one or more. on a binary
scale, and there is no need to synchronize with a random
coding sequence, or pseudo-random coding sequence, at
the door unit as is the case, for example, in the. system
I, US
of Patent 3,800,284~
When the new card is inserted into slot 12 of
FIGURE 1, -the door unit will read the new code on the
card and change -the current code by one or more on the
binary scale so that the old card will no longer be
accepted Provision may be made for the situation ion
which a card is issued for a particular room which is
not used, so that the unit in the door does not have
the opportunity of updating the current code,. This is
achieved by causing the system in the door to accept the
current code, the current code plus 1 binary unit, and
30. the current code plus 2 binary units. Therefore, even
though the current code has not been up-dated by the
previously issued card, it will still accept the new
card.
it
As mentioned above, computer 100 of FIGURE 5
is preferably small and portable so that is can be
carried to the individual doors when the occasion
arises and plugged into the individual door units, The
microcomputer unit MCKEE in each door unit has a small
memory which stores data as to the identities and times
of the last fourteen entries into the room, The computer
can be plugged into the door unit to read out this
information. lo as mentioned above, the. computer can
be used to program or reprogram the door unit
Lithium batteries do not gradually lose petunia-
trial when they begin to fail Instead, the potential
immediately drops to zero.. For that reason, a battery
indicator circuit is included in the system of FIGURE 3.
This circuit includes capacitor C2 Wheaties charged
through resistor R14 by the battery 26~ The resulting
voltage across the capacitor powers the microcomputer
MCKEE,
The internal resistance ox the battery 26 in
2Q creases as it begins to fail Therefore its voltage
will drop when failure is imminent during the -time it
is loaded ho solenoid Slick
Comparator A is used to look at the voltage of
battery 26 when it is loaded by solenoid Sly, If that
voltage drops below a certain threshold ! the. code
register in the memory of the microcomputer MCKEE. is
set to zero and the door unit will not accept any code.
Then, when computer 100 is plugged into the system, it
can open the door.
Microcomputer MCKEE includes an internal register,
and whenever a Cody is inserted into slot 12 of FIGURE 1,
the entrance code on the card is entered into the
resister, The microcomputer also includes a first
I
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internal counter which is set to the proper entrance
code of the door When a guest inserts his card into
slot 12 of FIGURE 1, and when the entrance code on
his card matches the code in the counter, pin PA goes
low and solenoid S10 is energized and the door may be
opened.
In order to preserve power r the solenoid is
first energized by a 50. millisecond DO pulse -to cause
it to latch; thereafter a 1 KHz square wave with a 50%
duty cycle appears at pin PA for five seconds to hold
the solenoid latched The solenoid obviously draws
less current from battery 26 during the square wave as
compared with the duration of the initial DO pulse.
Microcomputer MClQ also includes a second
internal counter Wheaties set, for example to one binary
count greater or less than the first interval counter, or
to any predetermined number of counts greater or less
than the first counter. If the next guest inserts his
card into slot 12, and if the entrance code on his card
2Q matches any count inclusive between -the first and
second counters, solenoid S10 is energized and the door
may be opened, The two counters are then stepped so -that
-the count on the firs-t counter matches the entrance code
on the new guest card, and so that the count of the
second counter is greater or less than the new count of
the first counter by the predetermined number of counts.
When the predetermined number of counts between the two
counters is greater than one, and when the system is such
that the solenoid S10 Jill be energized when the entrance
code on the new card matches any count inclusive between
the first and second counters, a new guest may still gain
access to the room, even if the previous guest for some
reason or another did not use the room,
~236~:~0
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Each guest card has a second code encoded on his
card representing the duration of his authorized occupancy
Jo of the room. As he inserts his card into slot It,
I: another counter is set in accordance with the duration
code, This latter counter is then counted down to zero
by the internal clock of the computer. When the counter
reaches zero, it increments or decrements the previously
described counters my the predetermined amount and the
: present card is no longer effective
Computer MCKEE. also includes an internal maid's
: entrance register Wheaties set to a particular code.
When a maid's card is inserted into slot 12 having a
code matching the particular code:, solenoid S10 is
energized and the door may be opened. Each maid's card
also has an identity code which identifies the holder
This code is stored in the computer's memory, together
with the time of access The microcomputer cluck, how-
ever/ will not respond to the Midas card if the privacy
swish is closed :
A similar internal register and identity storage
is provided within the computer for the master cards,
: and for the emergency keyword As noted above the emergencycard will operate the. solenoid S10.~ even though the
; privacy switch 30 is closed.
25. The identities stored in the memory of computer
MCKEE, and times of access, canoe read by plugging
computer 100 of FIGURE 5 into the circuit of FIGURE I.
The microcomputer MCKEE includes a clock genera-.
ion controlled by crystal Al, and counting circuitry for
: 30 indicating real time, so that the time of the various
entries can also be stored in its memory The unit in
the door records every entry into the room on an
elapsed time basis, When the. computer lo its plugged
.~,
-20-
into the circuit of FIGURE 4, the computer responds to
the elapsed time readings of the door unit to provide
a read-out of the real time of each entry,
The invention provides, therefore, an electronic
lock system in which each door has its own self-
contained microcomputer controlled unit which is not
wired to a central computer, and which is battery
operated by a self-contained battery, The unit is small
and light, and it may be readily removed from the door
and replaced as a single unit, should the need arise,
The system of the invention is conceived so that
the individual guest cards can be programmed to expire
after a selected time interval. also, non-use of any
issued guest card will not affect the operation of the
system. In addition, the individual door units keep a
record of the identities of all hotel personnel entering
the corresponding room, and the times of each access.
The desk computer electronically codes each guest
card as it is issued, and i-t eliminates mechanical card
punches. The card itself is a simple, programmable metal
card which is magnetically encoded and which is read on
a proximity basis with no moving parts in -the reader
The card can be reprogrammed and reused countless times.
The desk computer is small and light and readily
portable It can be carried to any particular door and
plugged into the door unit, as described above, to read
information stored in the door unit, and to start up
the door unit.
It will be appreciated that while a particular
30- embodiment of the invention has been shown and described,
modifications may be made, It is intended in the claims
to cover all modifications that come within the true
spirit and scope of the invention
