Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
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Field of the Invention - The present invention relates
to controlled access and more particu]arly to systems which
are operable without a key and are especially adaptable for
application in vehicles such as automobiles. -~
Description of the Prior Art ~ After automobiles gained
general acceptance by the consuming public, mechanisms were -
devised for the purpose of limiting their closure and opera-
tion. The conventional key operated tumbler lock was readily
available for such applications as doors,glove boxes, trunks
and ignitions on automobiles, although security devices ;~
operable without a key were soon being sought.
One such system is described in United States Patent
1,251,365 entitled Permutation Lock which involves relatively
complicated interlock mechanisms using electromagnets to
position tumblers in a bolt which controls the movement of
a mechanical component intended to be locked The system
is button operated and the buttons must be pushed in a prese-
lected sequential order for operation. The system is con-
sidered mechanically complex, heavy and bulky and is generally ;
unsuited for many current day automobile applications.
In United States Patent 1,2989177 entitled Combination
Lock for Automobiles, the inventors describe a somewhat
analogous system using a plurality of interchangeable keys
having selected areas of conducting and nonconducting sur-
faces thereon such that when the keys are mechanically
adjusted by the operator to a prearranged disposition,
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various electrical circuits are completed and the interlock
is bypassed. Another very old system is described in United
States Patent 1,587,75i entitled Automobile Lock which is
electromechanical in nature and is operable by properly in-
serting a plug into one of a plurality of receptacles and
manipulating the position of the plug. The concepts in each
of these two patents are feasible but impractical by current
day standards because of their size, complexity and relatively
inflexible codeability.
More recent variations of the relatively cumbersome
locking systems described above are disclosed in United States
Patent 2,819,770 entitled Means for Securing a Motor Vehicle
Against Theft and United States Patent 2,964,733 entitled
Automobiles or Like Vehicles Fitted with Theft Prevention
Devices.
The inventors of Door Locking Means disclose in United
States Patent 3,353,383 a combination lock mechanism that
must be properly decoded before a latch member can be actu-
ated to allow a door to be opened. The system is operated
by push buttons and is essentially mechanical in nature,
being organized such that if the push buttons are not ~;
operated in the suitable sequence, not only is the latch
mechanism not free to move but an alarm is thereby triggered.
As is the case with much of the preceding art, the workable
system is relatively complex, heavy and inflexible. Further,
such mechanical systems tend to be relatively large, expen- ;~
sive, and limited in their applicability due to such factors
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as size, reliability and environmen~al sensitivity.
In United States Patent 3,024,452 entitled Multi-Digit
Electrical Door Lock, the inventors disclose a system which
is more electrical in nature. A group of push buttons is
combined with suitable circuits which respond to a preselected `~
;nput. In the event the buttons are operated in a wrong se-
quence, the elec~rical circuitry causes the system to become
immobilized and an alarm is initiated. The system is ~urther
characterized in that the code to which the system will re- ~ ~;
spond can be changed by mechanical manî.pulation o~ provided
selectors. Another concept is disclosed in United States
Patent 3~192,448 entitled Keyless Electric Lock wherein a
lock bolt is actuated when the available switches are acti-
vated in a preselected sequence in order to activate a sole-
noid in the system.
While some of the more recent inventions are clear
improvements over the preexisting art, the various security
s~stems a~aila~le can be characterized as mechanically ori~
ented although some do involve electromechanical or electri-
cal activation mechanisms. Nevertheless, such systems are
relatively massive, complex and rigid and although their
codes may be changed, such changes ordinarily require
mechanical manipulation of certain variable components.
The automobile industry in particular currently looks ~or-
ward to a consumer oriented security system having good ~`
market acceptance. Such systems should be easily operable,
include a capacity to change the access mode quickly and
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easily, and retain the secureness and reliability of the
overall locking system in an inexpensive and rugged embodi-
ment of reasonable size and weight.
SUMMARY OF THE INVENTION
A primary obJeet of the present invention is to control
access to a vehicle or other enclosure with a mechanism which
is operable without a key.
Aceording to the present invention, a Keyless EntryTM
system eomprises a eontrol station ineluding a keyless elec-
trical signal generator, logic means for processing suitable
eleetrieal signals from the control station, and means re-
sponsive to the logic output for eontrolling a mechanism
such as a loek. Typieally, a digital electrieal signal is
produeed at the manual eontrol station by sequential opera-
tion of a plurality of sensitized toueh points. The signal
is directed to a logic means which compares the generator
signal with a re~erence code and under acceptable conditions
` can be programed to accept a subsequent eonvenience code,
and provide an output which is amplified and directed to
an electric motor to change the physical position of a re-
straint in the entry system. ~ `~
.
The manual generation of the eleetrical signals at a
sealed control station and the processing of such signals
in electronic circuitry are prineipal features of the present
invention. Various codes arbitrarily selected b~ an operator
having a base code can be programed into the system. The
control station is activated with ordinary finger pressure
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and can be conveniently sized to be packaged to fit an or-
dinary door handle found on an automobile. The door latch
mechanism is either locked or unlocked in response to a coded
sequence of electric pulses which may be either permanent or
temporary. The control station has a finger sensitive key-
board and often contains piezoelectric switches, a positive
contact indicator and a light for illuminating the keyboard.
The invention can be operated with various response functions,
; particularly in automobile applications including activation
of the interior lights, unlocking of the hood, and activation ~ ;
of the ignition circuit or an anti-theft alarm.
The present invention is attractive in appearance and
is essentially weatherproof when installed in an automobile
door. The system provides improved security and can eliminate
the need or a key. The keyboard is simple to operate, can
be contained within a modest space allotment, permits the
use of ten digits and the concomitantly large number of
possible combinations of coded signals ~or activation.
In accordance with a specific embodiment of the
invention, there is provided an enclosure ha~ring a door con-
taining lock means, means for controlling entry to the enc-
losure comprises: a control station including means for
initiating a sequence of electrical pulses in response to
manually applied inputs such pulse initiating means being acc-
essible from the enclosure exterior; signal proce~sor means
which accepts pulse sequences from the pulse initiating means
and contains a base code which is permanently fixed in the
processor, the processor being capable of comparing such
pulses with the base code and producing a drive signal in
response to each set of electrical pulses matched to the base
~ code, the signal processor having means for receiving and
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retaining until programmed otherwise from the pulse initiating
means along a convenience code which is received subsequent
to and in combination with the base code, the signal `
processor including means for comparing pulse sequences from
the control station with the convenience code and for provid-
ing a drive signal in response to each pulse sequence which
matches either the base code or the convenience code, and
means ~or amplifying the drive signal to a p~wer level
sufficient to operate the lock.
In accordance with a further embodiment of the
invention, there is provided in a vehicle having a door con-
taining a power lock, means for controlling the lock which
comprises: a control station located at the door exterior and
including means for producing pulse electrical signals in
response to manual inputs, signal processor means containing ~`
a base code for receiving electrical signals from the control
station, for comparing such signalc; with the base code, and
for providing a drive signal whenever the input electrical
signals from the control station match the base code which is
~0 permanently incorporated into the signal processor means and
; is incapable of modification or elimination b~ signals from
the control station, and means for accepting and retaining
until programmed otherwise with the control station by a series ;-
of electrical pulses delivered to the processor in combin- `
ation with the base code, such series constituting a conven~
ience code which allows the signal processor to respond to ;~
electrical signals produced at the control station and provide
a processor output signal each time a series of signals matches
either the base code or the convenience code, and means for -
amplifying the drive signal to a power level sufficient to
drive the power lock.
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In accordance with still yet a further embodiment
of the invention, there is provided a control system which
comprises: a control station including an entry module which :-
is responsive to manual inputs and has a plurality of juxta-
posed locations each capable of providiny an electrical sig-
nal, particular series of which form signal sequences with
each individual electrical signal being identifiable with a
particular one of such locations, an electrical signal pro-
cessor for providing a processor output signal in response .;
; 10 to any preselected signal sequence from the entry module,
the processor including, means for retaining a base code as a
first preselected code, and for comparing a signal sequence
produced at the entry module with the base code, and for
providing a processor output signal each time a signal se-
quence matches the base code which is permanently incorporated
into the base code retaining means and is incapable of mod-
ification or eliminati.on by signals from the entry module, and
means for retaining a convenience code as a second preselected
code, and for comparing a signal sequence produced at the
entry module with the convenience code, and for providing a
processor output signal each time a signal sequence matches
~ the convenience code which is incorporated into the convenience :~
; code retaining means from the entry module alone by entering
in order the base code followed by a manual input from at least
one preselected location at the entry module and finally a
series of manual inputs arbitrarily selected by the operator
to become the convenience code, amplification means for in-
creasing the power of the processor output signal, and means
responsive to amplification means for controlling the oper-
ability of an apparatus used in combination with the control
a system~
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In accordance with still yet a further embodiment
of the invention, there is provided an entry system which
comprises: a movable member the position of which determines
the accessibility to a system or an enclosure, actuation means ~ ;
for changing the position of the movable member, means for
controlling the movement of the actuation means; a control
station having input means which are responsive to manual
inputs including a plurality of discrete locations capable of
producing an electric signal characteristic of each location, :
O an electrical signal processor having means for retaining
., .
as a base code a preferred order of such electrical signals and :-
for comparing as an input the actual order in which electrical
signals are produced by the input means to provide a processor
output signal each time an input code matches the base code i~
` which is permanently incorporated into the base code retaining
means and is incapable of modification or elimination by sig~
nals from the input means, the electrical signal processor ;
also having means for retaining until programmed otherwise
from the control station a sequence of electrical signals con~
stituting a convenience code which allows the signal processor
to respond to electrical signals produced ~t the control '
station and provide a processor output signal each time an
input code matches either the base or the convenience code
amplification means for increasing the power level of the
processor output signals; and means responsive to the amplif-
ier for moving the means controlling the movement of the
actuation means.
The foregoing and other objects, features and advan~
tages of the present invention will become more apparent in ~-
3~ the light of the following detailed description of preferred ~-
embodiments thereof as shown in the accompanying drawing.
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BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 is a block diagram of an overall system in :~
accordance with the present invention~
Fig. 2 is a block diagram with representations for .
some of the more significant interacting components in a system .
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on an automobile;
Fig. 3 is an exploded perspective view of a ~epresenta~
tive lock module used in the system;
Fig. 4 is a simplified schematic of a Keyless Entry
system designed for an automobile installation.
Fig. 5 is a functional block diagram of the lock module;
Fig. 6 is a simplified circuit diagram corresponding to ;~
the block diagram of the lock module;
- Fig. 7 is a functional block diagram of the central ~ -
processing unit and programable read only memory elements ~
of the module; and - ~ -
Fig. 8 is a simplified circuit diagram of the central
processing unit~
. . ... .
DESCRIPTION OF A PREFERRED EMBODIMENT
A sketch of a simplified Keyless Entry system in ac-
cordance with the present invention is shown in Fig. 1. The ~ ~
system as disclosed is a device which is suitable for mount- ~ -
ing in the door of a conventional automobile and the entire
nonmechanical portion of this system is typically packaged
in a volume represented by an ordinary bar of soap.
In Fig. 1~ an overall lock system 10 is shown with an
electronics grouping 12 comprisîng a control station 14, a
signal processor 16 and a signal amplifier 18, and an elec-
tromechanical grouping 20 comprising an exterior key station
22, an interior control station 24, a power lock driver 26
a lock 28, an interior door lock button 30, an exterior
handle 32 an interior handle 34, linkage 36 and a latch
plate 38.
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:re.l~ase- se~ ..Qnce of the loek sys-~em can ~e descr.ibecl
ln terms of the ~-loek diagrams shown in ~i.gs. l arld 2. An `,
opera~:or produces an input signal. sequellce /-~0 at the control ; .
xtation, I'he signal sequence is proces.sed electronically ,~
and compared with a reference signal in an electr:ic circu1.t ~ :
inc~.l t.l~ing a power supply 42, ~.ll of which .is ~escri~ed ln ~`
more detall herei.nafter. The input sequences which. suitably
~natc~L a coded reerence,sQquence in the proces~solA pass to the ~'
si~al ampll,ier ~o provide an elec~ronic~ grou~i.ng output
n signal 44. The power level of t:he signal 44 is suf.icient :
to activate t~le pow~r lock driver whi.ch is an element :in t.h~ ;,.
elPc~romec~anîcal ~roupi.ng 2Q an.d is ~"ypicall~ 3 so'lenoid : ;
or a mo~or, A cycle o~ the lcck driver moves the lock per
se, el.~J.nlnates a restraint i.n the linkage 34, and either the
e~.terior handle 30 or the intelAio:r handle 32 may ~e ma~ipu~
l~te~ callsing the linkage 36 to throw the latch plale 38
thereby releasing the entry member such as a door or trunk
1id. In addition to the door 'lock actuation, th~ s:i.gnal 44
ean ~e used to dr.ive various other ~unctional se~uences i~
2Q so desi.red. Alternatively either the exterior ~ey st,ati,on
?~ locataed on he ~utsi~.de of the door or the inter.ior con^~
trol s~ati.on 24 can control the mechanical group.ing. These
two si~es operate ,independent of the grouping 12 and allow
~ne door loc'k to be actuated from inside the enclosure wi~.h
a si~.pl.e switch or frnm outside the enclosure with an op- - -
~io.rlal ke~ w~.ich is usable in the conventional m~nner as
an alternate me.t'tlod of entry.
342
In an electric circuit which is essentially in
parallel with the electronics grouping output signal 44, a
relay trigger signal 46 from the grouping 12 triggers a relay
48 connected to the power supply ~to provide various outputs
as shown in Fig. 2. For example, a first relay output 50
energizes a keyboard bulb 52 mounted proximate to the control :~
station 14, and a second relay output 54 activates a group
of courtesy lights 56 interior of the car.
An exploded perspective view of a preferred
Keyless Entry module 58 is shown in Fig. 3. The assembly
comprises a touchplate 60, a coverp]ate 62, the keyboard
bulb 52, the signal processor and the signal amplifier.
Also shown for the purpose of clarity are the relay 48 and
the power supply 42. ~he touchplate comprises a substrate
6~ which is electrically conductive and usually a metal,
a layer 66 of piezoelectric material and a plurality of ~
electrodes 68. The application of pressure such as can be ,-
applied with the touch of a finger at one of the number
locatlons generates a ~oltage between the substrate and the
adjacent electrode and results in the touchplate signal 70 ~ -~
which are directed into the signal processor 16. A more -;
extensive discussion of the details of construction and
operation for a touchplate of the type described is provided
in Canadian Patent Application Ser. No. 288,349, entitled
Signal Generator which was filed on Oct. 7, 1977 and is held
with the present invention by a common assignee. While the
piezo~ectric touchplate has been found to be particularly
342
suited -for the module construction, more ordinary apparatus
such as push buttons or toggle switches alone or in combina- ~
tion with a flexible boot are also feasible. ~;
A schematic representation of an entry system as applied
to a two-door automobile is shown in Fig. 4. The system îs
simplified considerably to show a representative electrical
network suitable for supporting two door locks and one trunk
lock. Most of the elements shown have been described pre- -
viously in the block diagram descriptions although a trunk
release switch 72 which is commonly located in the glove box
of an automobile is also included. In a typical application
the keyboard and courtesy lamps shown are lighted for a
period of ten to fifteen seconds after the final entry is -~
made at the control station.
When the present invention is committed to an applica-
tion such as access through a door or the trunk in a passen-
ger car, the overall operation involves the keyless control
of the logic system in combination with a power door lock.
Typically, the fingers of the operator contact the touch- ;
plate and when a sufficient force which is ordinarily in .;
the range of a few ounces to a few pounds is applied thereto,
a voltage is generated between the touchplate and an elec-
trode. As soon as such a signal is generated from any one
or more of the touchplate electrodes, the associated input
signal activates the relay 48 and triggers multiple re-
sponses. The first output signal 50 from the relay ener-
gizes the keyboard bulb 52 so that during periods of limited
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visibility, the operator can be accurately selective in his
manipulations at the touchplate. In addition, ~he relay pro-
duces the second output which activates the courtesy lights
in the automobile enabling the operator to view the en~ire
interior prior to unlocking and entering the vehicle. -
The entire grouping 12 namely the control station, the
s~gnal processor and the signal ampli~ier is relatively
simple and compact. The volume of such a package is typi-
cally three to five inches in length and perhaps an inch
wide and an inch deep. In addition to being readily enclosed,' ~-
the module as described herein ;ncludes no buttons or mechan-
ical switches so that the entire package can be made rela~
tively insensitive to the environmental conditions and more
speci~ically waterproo~. This feature alone is very desir-
able since the difficulty and inconvenience of a frozen key
lock is avoided. The dimensions of the module are convenient
~or integrating the package into either the conventional
side door locks or trunk lock presently ~ound on automobiles.
The entry system has a permanent signal sequence stored
in the signal processor and anytime the correct code is in-
troduced at the control station, various prearranged output
signals are generated allowing the electromechanical group- ;
ing and the systems responsive to the relay to be operated.
This code may be for the embodiment shown, any ~ive digit
number based on the numerals zero through nine. The touch- ;
plate 60 as shown in Fig. 3 has ~ive pads or touchpoints
each o~ which is associated with two numerals and a single
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corresponding electrode. The arrangement makes available
a greater flexibility in numerical code selection although
the number of statistical combinations possible with the `~
five electrode system which is approximately three thousand
does not change. Five input locations are considered con-
venient to allow a suf~iciently large reserve of possible
combinations to accommodate the door locking requirements
in an automobile application.
The permanent or base code which will operate the sys- `
tem described is known to a limited number of operators and
thereby guarantees limited access to the vehicle without the
necessity for carrying a key. ~owever, under some circum~
stances, an operator may wish to provide entry to the auto-
mobile ~or a limited duration of time. Under these circum-
stances, the operator can provide temporary access to the
system by entering the base code followed quickly by touch-
ing the one/two digit location and then entering a conve-
nience code. The entry of a convenience code is controllable
by alternative conditions precedent as well, the more imme-
diate of which include the use of the door key at station 22
or entry of a particular program sequence other than a single
signal from the one/two digit location. Since the system
will respond to either the base code or the convenience
code, the operator can provide a person such as a parking ~ `
lot attendant with the temporary access by revealing to him
a convenience code. When the operator wishes to revoke
such access, he merely enters the base code which erases
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the temporary access code. Similarly the circuitry can be
allowed to respond in a manner whereby a base code entry -~
followed by entry o~ the one/two indicator clears the pre-
viously stored convenience code. This programable feature
of the system can be used repeatedly with the same or dif-
ferent convenience access codes being provided at the will
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of the operator who is cognizant of the base code. ~ ;;
The essence of a typical signal processor 16 is shown
in b]ock diagram ~orm in Fig. 5. The five touchplate signals
70 are entered into a central processing unit (CPU) 74 which -
communicates with a programable read only memory (PROM) 76
and together provide a signal which is increased in power
in the amplifier 18 and appears ultimately as the output
signal 44 which drives the power lock driver 26.
Actual wiring for connecting the integrated circuits
with the associated element is shown schematically in Fig. ;~
6. The entry module 58 as shown in detail in Fig. 3, con- ~-
tains five distinct number locations, each of which produces
an output signal represented as Kl through K5 on the CPU.
The Kl through K5 signals are typically two to three volt
sine waves with some noise present. These K signals are ;~
decoded to binary form resulting in signal Ll through L3.
The CPU generates signals Sl through S3 which correspond ;~
to the sequence of K signals. These six output lines then
address a programable read only memory (PROM) 76 and generate
corresponding outputs 01 through 03 which are entered into
CPU which then become the next sequence number Sl through S3. ;
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Therefore for every Kl through K5 input that is in the proper
order, a new sequence number is obtained (Sl - S3, 01 - 03).
This process continues until the unlock sequence number is
obtained and a signal is generated at LO. If an out of se-
quence Kl through K5 is input, the PROM generates sequence
000 at 01 through 03 and the combination must start over.
A grounded network 78 generates a clock frequency for the
purpose of synchronizing all the internal signals on the
CPU and generating the feedback to the CPU which is present
at all times on output LO. Once the correct coded sequence
of numbers is introduced at Kl through K5, a signal is gen-
erated at output LO which powers two amplifier transistors
80 thereby driving the lock mechanism.
Faults are detected in the transistors 80 with the pre-
viously mentioned feedback signa]. which is always present on
output LO. As long as the transistors are operating cor- ;~
rectly this feedback is present also at collector 82. The
signal is not present in the event either o-f the transistors
fail Should this occur, immediately following the next
clock signal, a pulse is generated at CBl output which turns
on the silicon controlled rectifier 84 and blows a fuse 85
disconnecting the power supply. With this protective cir-
cuit, no failure of the transistors 80 is capable of turning
on the output and actuating the lock mechanism.
The CPU also generates signals in response to random
keyboard inputs, which result in the illumination of the
touchplate through amplifying transistors 86 and the light
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emitting di~de tL~D) shown in Fig. 6. An LED is sometimes
incorporated into the system somewhere on the keyboard as
` a positîve feedback indicator. The use o~ an LED in this
: manner allows the operator to confirm visually that each
input motion is in fact producing the intended input elec-
; tric signal. A pair of diodes 88 is provided essentially
to regulate the current supply to the integrated circuits
and a pair of second diodes 90 protect against overvoltages
and reverse polarity o~ the power supply. During long periods
of nonuse, the quiescent current draw of the circuit should
be minimized and therefore, the programable read only memory
has power only during the time that the touchplate is illumi- ~ `
nated which is typically approximately ten seconds.
A functional block diagram of the CPU and the PROM is
provided in Fig. 7. The interface area 92, a random access
memory and decoder 94, a decoder 96 and an illuminati~n
signal generator 98 for the illumination time delay and an
unlock signal generator 100 are shown. Provision for a
clock to synchronize all of the signals present, means for
protecting the integrated circuitry, and a power-on resetter
are also shown.
A somewhat detailed schematic of the integrated cir-
cuitry of the CPU is described in Fig. 8. A power-on reset
circuit 102 protects the circuitry from overvoltages and
eliminates spurious signals which occasionally develop and
might otherwise activate the power locks. At each input ~'
station Kl through K5, a Schmitt trigger 104 is provided
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to square the input wave and a debounce delay circuit 106
is provided to prevent false inputs due to either a low power
or noisy signal. The debounced circuit also prevents the
simultaneous actuation o~ more than one key. Rather than
to attempt the unwieldly task of handling ~ive individual par-
allel input lines, the output from the debounce circuit is
processed through a binary encoder 108 and s~ored in a three
bit latch 110 for addressing the programable read only memory
shown previously. The latch prevents the loss of signal once
the key input is removed. A second three bit latch 112 re-
ceives outputs 01 through 03 from the programable read only
memory and stores such outputs as part of the address for that
same programable read only memory. In this manner~ the coded
sequence occurs only i~ the correct address is inserted in the
programed sequence. An OR gate 114 generates the appropriate
; signals to strobe the latches and trigger an illumination de-
lay 116 which is ordinarily ten to fifteen seconds, a period
during which the keyboard and courtesy lights are energized.
A~ter a correct permanent code sequence has been ac~
cepted, and ~ND gate 11~ triggers an unlock ~imer 120 which `
simultaneously resets the temporary storage means in the ~
random access memory (RAM) 94. A subsequent signal from Kl ~ -
triggers a memory flip-~lop 124 allowing the next five Kl
through K5 signals to be read into the random access memory
and the memory flip-flop resets. A penalty delay counter
125 and a counter 127 are incorporated to inhibit rapid and
continuous sequential operation of all possible codes. Ty-
pically after a predetermined number, twenty five for e~ample,
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of keystrokes is accomplished with the generation o~ an un-
lock signal~ the penalty time delay counter is enabled to
inhibit subsequent input signals during the next several
seconds or longer. ~;~
A write counter 126 provides a number sequence which
becomes half of the address for the random access memory.
The remainder o~ the address comes from the key address out-
puts Ll through L3 and the correct sequence is generated by
~he same feedback scheme used in the programable read only
memory, namely,for the normal sequencing of the convenience ~;
code, each input must be preceded by a correct input in order
to have present the correct address for the input in question.
When the address at the output of the random access memory
is correct~ t~le unlock timer 120 is triggered to generate an
appropriate unlock signal. A clock circuit 128 comprising
inverters, ~eedback resistors and capacitors as is well known,
in combination with a monostable multivibrator 130 provides
a very short signal pulse which also appears at the lock out-
put i there is no unlock signal thereby providing extremely
narrow pulses to the output transistors to detect correct
operation. The extremely narrow output pulse is fed back `~
at FBl into a two bit shift register 132 so that i~ two suc-
cessive signals are not detected at the collector of the last
output transistor 80 9 an output CBl will be generated to blow -
the fuse 85.
The apparatus and circuitry discussed above are oriented
primarily toward automobile entry applications in order to
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342
describe a complete system in an understandable context.
However, the invention has utility over a wide range of
applications whic'n include garage and other door operation
in commercial and private buildings, access to equipment
such as copying or automated credit machines, elevator or
automobile ignition operation, and entry to restricted recre-
ational facilities.
Although the present invention has been shown and de-
scribed with respect to preferred embodiments thereofg those
skilled in the art should understand that various changes
and omissions in the form and detail thereof may be made
therein without departing from the spirit or scope of the t
invention.
CLAIMS
Having thus described a typical embodiment of our
invention, that which we claim as new and desire to secure -
: b~ Letters Patent of the United States is:
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