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BACKGROUND OF THE INVENTION
This invention relates to remote signalling systems for use with in-house
telephone systems and more particularly is concerned with a data
signalling system that may be connected to operate through a PABX system
without need for any modifications to any of the existing equipment.
Numerous applications for remote signalling systems are found in connection
with the conventional in-house telephone systems that are used in motels,
hotels, hospitals and the like. Such systems typically include a plurality
of area or room telephones each being either of the conventional rotary
dial or tone dial signalling type and each having a separate telephone
line, a plurality of trunk lines, and a central telephone switching unit
such as a PABX system operable to selectively control connection between
the telephone lines and the trunk lines.
Various types of signalling systems for indicating room status have been
proposed for motel and hotel use, for example: See U.S. Pat. Nos.,
3,614,325; 3,742,141; 3,777,065; 3,854,009; and 3,892,922. Such systems
are complex and require various modifications to the conventional
telephone system which in general are unduly expensive. In addition, these
systems require access to the telephone lines of each room and seriously
lack versatility and flexibility.
While there is general agreement as to the value of remote signalling
systems in conjunction with in-house telephone systems, the marketing
needs have not been met because of the above mentioned drawbacks to the
prior systems.
SUMMARY OF THE INVENTION
The present invention provides a remote type data signalling system that
features ease of installation; that actually requires no modification of
existing telephone systems; that enables data to be transmitted from any
one of the in-house phones and that can be adapted to all types of data
reporting functions that may arise in connection with the particular
business situation.
The invention is suitable for use with either rotary dial or tone dial
systems and has good noise rejection and isolation to preclude responding
to false signals and to avoid interfering with the operation of the phone
system.
More particularly, the invention provides a data signalling systems
operable through an in-house telephone system that includes a plurality of
area telephones each having a telephone line, a plurality of trunk lines,
and central telephone switching means operable to selectively control
connection of the telephone lines to the trunk lines, the signalling
system having input digit clock means connected to produce a first digit
clock signal in response to selection of one of the trunk lines by any
selected one of the area telephones and connected to produce a sequential
digit clock signal in response to each subsequently dialed digit received
from the selected trunk, logic means responsive to each digit clock signal
to receive from the selected trunk line each sequentially transmitted set
of conventional digit defining telephone dial signals transmitted by the
selected area telephone and to convert each set to a separate
corresponding set of digital signals representative of the corresponding
dialed digit, and utilization means responsive to each separate set of
digital signals to provide a digital read-out representative of such sets
of telephone dial signals.
The disclosed embodiments utilize a digital printer to present a display
that can be triggered either in response to a pre-determined digit code or
in response to hang-up. While the illustrated printer is a numeric device,
a unique over-ride circuit arrangement causes the printer to print alpha
characters.
Additional features include use of control gates triggered by unique signal
patterns of the type generated by the conventional A, B and C telephone
trunk relays.
Further features that evidence the versatility of the system include the
simplicity of handling not only status data but data such as restaurant
charges and time of day information.
The system readily accommodates memory functions wherever an accumulation
of data need be presented.
Other features and advantages of the invention will be apparent from the
following description and claims, and are illustrated in the accompanying
drawings which show structure embodying features of the present invention
and the principles thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings forming a part of the specification, and in
which like numerals are employed to designate like parts throughout the
same:
FIG. 1 is a perspective view of a desk top console unit incorporating an
electronic data signalling system in accordance with this invention;
FIG. 1A is a fragmentary view illustrating a section of paper tape having
print-out data illustrating the format in which the data is presented;
FIG. 2 is a block diagram illustrating an in-house telephone system in
association with a first embodiment of the data signalling system of this
invention;
FIG. 3 is a digital timing chart illustrating the typical signal patterns
occurring in the operation of FIG. 2 embodiment;
FIGS. 4A and 4B, taken together, comprise a composite detailed wiring
diagram for the FIG. 2 embodiment; and
FIG. 5 is a block diagram illustrating a second embodiment of the invention
adapted for use with telephone systems of either the dial pulse type or
the tone dial type.
GENERAL DESCRIPTION
Referring now to the drawings, two specific embodiments of an electronic
data signalling system, as disclosed herein in block diagram form in FIGS.
2 and 5, are arranged for direct connection to an in-house telephone
system. Such a telephone system conventionally includes a plurality of
area telephones T each having a telephone line L leading to a central
telephone switching means such as a PABX which is generally indicated at
CT and includes a plurality of conventional trunk lines. As is well known,
the PABX is operable to selectively control connection of the telephone
lines to the trunk lines. Typically, a pre-determined trunk is selected by
dialing a particular access digit, for example, dialing 9 usually selects
an outgoing trunk.
Each of the electronic data signalling systems shown in FIGS. 2 and 5 is
arranged to be connected to the telephone PABX equipment via a control
cable. In the FIG. 2 embodiment, the control cable has five pairs of wire
and the system is specifically designed for connection to certain existing
in-house telephone systems wherein the area telephones are of the dial
pulse type. In the FIG. 5 embodiment, the input circuits for the data
signalling system require only two pairs of wires so that a standard
telephone JKT line cord can be used as the control cable. In addition, the
FIG. 5 embodiment is suitable for use with area telephones of either the
dial pulse type or the Touch-Tone type.
In accordance with the invention, each of the electronic data signalling
system embodiments is conveniently arranged in the form of a
self-contained desk top unit U having a conventional 110 volt AC power
cord and having a control cable for connection to a selected one of the
telephone PABX trunk lines. No additional equipment is required to permit
the unit to respond to and record data supplied over any one of the area
telephones and no modifications of any type need be made to the
conventional telephone system so that installation is of utmost
simplicity.
In the embodiments shown herein for purposes of illustrative disclosure, a
digital panel printer designated generally at 11 in FIGS. 1, 2, 4A, 4B and
5, provides the data display and data recording functions. The printer
shown herein is the Datel Systems Model DPP-7A5 type and the detailed
circuitry disclosed herein is arranged for direct interconnection with
that particular printer, but as will become clear to those skilled in this
art, the invention is not limited to use with such a printer.
As shown in FIG. 1, the printer 11 is arranged as a plug-in unit disposed
centrally in the front panel of the desk top unit U and normally is fixed
in place by a thumb screw 11T to allow for convenient removal of the
printer for replacing the paper tape t on which the data is displayed and
recorded. The illustrated printer model has a six-column print format
arranged with a first group of four digits, a blank space and a second
group of two digits. The printed character is in the form of a
conventional seven segment digit. The printer also contains the
electronics for the print functions and includes a power supply having a
+5 volt logic supply both for the printer components and also for the
signal processing circuitry of this invention.
The particular printer accepts full parallel BCD inputs for the six data
columns followed by a print command signal. While the printer is a numeric
printer, adaptations are made to the inputs to columns five and six of the
printer's logic to cause the device to print alpha characters for
facilitating interpretation and clarity of the data read-out.
For purposes of illustrative disclosure, the electronic signalling system
of the invention is described in connection with a typical hotel/motel
application for providing data as to room status. Specific details given
in connection with such a typical operation are for the purpose of
illustrative disclosure and not for limiting the scope of the invention or
its application to other uses.
Typically, the status system unit U is connected to a selected one of the
telephone PABX trunks such that any one of the area telephones T may
communicate with the status system unit by first dialing an access digit
for selecting the corresponding pre-assigned PABX trunk. In addition, more
than one of the desk top units may be connected to the same PABX system.
For example, one unit may be located at the main desk and another unit may
be located at the housekeeper station. The area telephones may include not
only the telephones in each guest room, but one or more maid's phones or
administrative personnel's phones. In addition, a restaurant cashier's
phone may access the status system of this invention to record restaurant
charges to a guest's room account.
For application as a room status system, the first four data columns of the
printer 11 are available to show the particular room number. In larger
motel operations four digits are required, but in smaller operations where
only three digits or less are required, appropriate wiring modifications
can be made to bypass or disable the 3rd or 4th printer columns. Normally,
however, for recording restaurant guest charges, four digits are required
and, for the particular printer arrangement described herein, a set of
four digits must be dialed to locate the decimal point in the correct
position. Thus, four digit amounts such as 12.98 automatically will print
with a decimal point as shown in the top line on the tape which is here
shown also includes the symbol Fd for food. If a restaurant charge were
$2.98, it is necessary to first dial a zero, followed by the digits 298 in
order to have the decimal point at the correct location. As shown on the
tape, the symbol Li is next to the $2.98 to indicate that the charge was
for liquor. Referring again to the tape, three status conditions relating
to the guest room itself are shown wherein CL denotes that the room is
clean, HP denotes that a housekeeper is needed and OC denotes that the
room is occupied and cannot be cleaned. Because of special wiring applied
to the printer, the symbol CL is printed in response to the dialing of
digit 2 which corresponds to the letters ABC on the phone dial. Similarly,
HP is printed in response to dialing of the digit 4 and OC is printed in
response to the dialing of digit 6. For the restaurant charges, the symbol
Fd is printed in response to dialing of the digit 3 and the symbol Li is
printed in response to dialing of digit 5.
The general operating procedure of the system, for example, as used by a
maid to signal the status of a particular room is as follows: (1) lift the
telephone handset and listen for the dial tone and dial the access digit
7; (2) if a busy tone is heard, the signalling system is in use and the
maid must hang up and dial again; (3) if the unit is available an answer
beep is transmitted to the area telephone; (4) the maid then dials the
room number followed by one of the status codes previously described; and
(5) the maid hangs up the telephone handset to send a print command signal
to the unit to cause the room number and status symbol to be printed on
the tape.
A somewhat similar procedure is followed for recording restaurant charges.
In this case the cashier picks up the handset and dials the access signal
7 to cause the telephone system to seize the electronic status unit U
which emits the answer beep for about one-half second. The cashier then
dials the guest's room number and the status digit 7 for a restaurant
charge. The printer is specially wired to respond to the status digit 7 to
immediately print the room number followed by the symbol CG. The cashier
hears an audible tone during this printing cycle. The signalling unit
automatically resets and activates a decimal point enable circuit to cause
a decimal point to appear between the second and third digits of the next
entry. The cashier then dials in a four digit set representing the actual
charge and the proper status digit. If the actual charge requires three
digits or less, the printer automatically blanks the leading zeros. The
cashier hangs up the phone and the dollar amount and code are printed on
the line following the room number and charge code.
DIAL PULSE EMBODIMENT
The embodiment shown in FIG. 2 and in FIGS. 4A and 4B is arranged for
connection to certain existing in-house telephone systems having dial
pulse type area telephones. The telephone PABX trunk to which the
electronic data signalling system is connected may be completely
conventional and thus, typically includes three relays commonly referred
to in the art as the A, B and C relays which include A, B, C contacts as
shown in FIG. 4A. The A, B, C relay contacts generate the actual dial
signals which are supplied through the telephone PABX trunk to the
electronic data system of this invention.
Referring to FIG. 3, a dial pulse signal pattern representative of the A,
B, C relay inputs is shown for an illustrative sequence wherein the user
dials the pre-assigned access digit 7 (to cause the PABX trunk to seize
the electronic data system) followed by the digits 4232. The waveforms
A-1, B-1, C-1 in FIG. 3 show the relay generated signal pattern.
The A contact closes at time T-1 when the telephone PABX trunk is dial
accessed. Operation of the A relay energizes the B relay whose contacts
close at T-2 and remain closed for the duration of the call. Beginning at
T-3, the A contact opens and closes (or pulses) in unison with the dialing
of digits and provides a pulse train to the input logic of the signalling
system. Thus, beginning at time T-3, the A relay pulses four times to
represent dialing of the digit 4. The C contact closes shortly after the A
contact begins pulsing to provide a signal indicating that a digit is
being dialed. In FIG. 3 the C contact is shown closing at time T-4 and
opening at time T-5. Similarly, beginning at time T-6, the A relay pulses
twice with the C closing beginning at time T-7 and opening at T-8. The
remainder of the dialing is evident in the digital time chart.
The input section of the signalling system unit as shown in both FIGS. 2
and 4A includes an integrated circuit IC-15 functioning as a contact
bounce eliminator to condition the relay contact closures into clean logic
signals and thereby avoid any false signalling in the high speed digital
circuits. Thus, the wave forms A-1, B-1 and C-1 in FIG. 3 may be
understood as being the output signals from the contact bounce eliminator
IC-15 as shown in FIG. 4A.
As shown generally in FIG. 2, the input logic signals derived from the
contact bounce eliminator IC-15 are applied to a set of gates including an
answer gate 20 which is connected to trigger an answer tone timer 21 when
the status unit is first seized by the telephone PABX trunk. The timer 21
generates a pulse typically of one-half second duration to activate an
answer circuit 22 consisting of an audio tone generator and transformer
which connects to the trunk through one of the five wire pairs previously
referred to. The timer 21 is connected by wire 29 B to reset storage
counter 29 to clear it of previously stored binary data. The circuitry for
the described answer function is shown in FIG. 4A wherein the answer gate
is shown to include an inverter gate IC-9 and a NAND gate IC-13 connected
to actuate a timer IC-17 which has a connection path to a tone generator
22, such as a Mallory SC628 Sonalert, for sounding a one-half second
audible tone as indicated at AT in FIG. 3. For convenience, the connection
path to the tone generator 22 is made through printer terminal connections
and a spare NAND gate IC-2 within the printer 11 in the case of the
particular illustrated embodiment. The audio tone signal from the
generator 22 is coupled through a transformer 23 to the PABX trunk to
notify the user that the status unit has been seized in response to the
dialing of the access signal digit 7.
The status unit has an indicator light 24 on its front panel as shown in
FIG. 1 to indicate that the telephone system has been made "busy" whenever
one of the area telephones has accessed the connecting trunk or whenever a
normal/busy switch 25 on the front panel is in "busy" position or whenever
the printer 11 is out of paper or is temporarily removed from the
enclosure. When the busy light is lit, anyone dialing the status system
will hear a busy tone generated by the PABX equipment.
With reference to FIG. 2, an in-use gate 26 is shown connected to receive
the signals from the contact bounce eliminator IC-15 to act as a control
gate for actuating the busy light 24 on the front panel. With reference to
FIG. 4A, this function is served by the NAND gate IC-13-A which controls
the voltage applied a transistor Q1 which has a light emitting diode 24 in
its collector circuit to serve as the "busy" light on the front panel of
the unit.
The primary control and interface circuitry for receiving signals from the
telephone PABX trunk, as shown in block diagram form in FIG. 2, includes
input circuitry having a digit clock gate 27 responsive both to the
selection of the trunk line by an area telephone and to the dialing of
each digit as received from the trunk line; and logic circuitry including
a reset gate 27 A responsive to hang-up to reset counter 28; the digit
enable counter 28 being incremented by a pulse CP (See FIG. 3) from the
digit clock gate 27 and connected to a multi-section binary digit storage
counter 29 to sequentially enable the proper digit storage counter section
as the successive digits are dialed as is shown by the wave forms N-1 to
N-5 in FIG. 3; and a pulse clock gate 30 responsive to the A relay input
pulses and connected to all sections of the digit storage counter 29 to
feed each such counter section a number of pulses equal to the number
dialed for the corresponding digit. Thus, as each section of the binary
storage counter 29 is successively enabled by the digit enable counter 28,
it counts the A relay input pulses and stores such count in binary form
for presentation to the printer inputs.
Thus, as illustrated in FIGS. 2, 4A and 4B, for a situation where four
digit room numbers are to be printed, each of the sections IC-3-1, IC-3-2,
IC-5-3 and IC-5-4 of the digit storage counter 29 corresponding to the
first four columns connects directly to the first four input columns of
the printer 11, whereas the storage counter section IC-6-A for the last
digit that denotes the room status is connected through a unique alpha
conversion logic 46 for converting the binary signal pattern corresponding
to the particular status digit into appropriate inputs to columns 5 and 6
and to certain segment over-ride terminals of the printer for causing the
single digit status code to produce a double letter print-out. Thus, after
the user has dialed the complete sequence of digits which have been
processed through the digital circuits, the signals are stored for
presentation to the printer when the user hangs up the telephone handset
and causes the PABX status trunk to drop the connection. The sequence of
the A, B and C relays, as derived from the contact bounce eliminator
IC-15, when the user hangs up as shown at T-H in the timing chart of FIG.
3, actuates a print command gate 31 to generate a print command pulse PC
to cause the printer 11 to print the stored binary signal data.
The stored binary signals in IC-3-1, IC-3-2 and IC-5-3 and IC-5-4 for
columns one to four directly control the printer's inputs. The stored
binary signals in IC-6-A for columns 5 and 6 are processed by the alpha
conversion logic 46 for presentation to the printer. The printer advances
the tape and generates a print tone command signal that is applied to the
generator 22 over line 22 L. At this same time, the digit enable gate 27
responds to the relay inputs associated with hang-up to reset the digit
enable counter 28. The storage counter 29 will be reset by timer 21 as
part of the answer tone sequence of the next call.
A specific circuit arrangement for the control and interface circuitry is
given in FIGS. 4A and 4B wherein the digit clock gate 27 is shown to
include an AND gate IC-8-D and associated inverter IC-9-D to increment the
digit enable counter 28 as each digit is dialed and the reset gate 27 A is
shown to include a NAND gate IC-12-D and an associated inverter IC-9-E to
reset the digit enable counter 28 upon hang-up. The digit enable counter
28 consists of a decade counter IC-1 connected through a set of inverter
gates IC-2, there being one inverter gate IC-2 connected to each section
of the digit storage counter 29.
Correspondingly, the clock gate 30 consists of an AND gate IC-8-C and an
inverter IC-9-C serving to combine the inputs to clock each section of the
digit storage counter 29 in accordance with the number of A relay input
pulses associated with that particular digit. As shown in FIGS. 4A and 4B,
each integrated circuit element contains two sections of the digit storage
counter 29. Thus, sections IC-3-1 and IC-3-2 are portions of a single
integrated circuit element. Thus, the left hand section of IC-3-1 (See
FIG. 4A) serves as the binary counter for the column 1 position of the
printer 11 and it is enabled through the integrated circuitry IC-1 and
IC-2-1 in order to receive, count and store the number of pulses
representing the first digit dialed. With reference to FIG. 3, the wave
form labeled N-1 shows that the binary counter section associated with
column 1 is enabled during the dialing of the first digit so that the set
of four clock pulses defining digit 1 are received and stored for
presentation to the printer. The particular binary counter disclosed can
present appropriate binary signals to the printer for any dialed digit
between 1 and 9. In order to convert a dialed zero, which corresponds to
ten pulses, into a binary zero, IC-4, IC-10 and IC-11 are provided.
When the second digit is dialed, it will be noted that the section IC-3-2
of the digit storage counter corresponding tio printer column 2 is enabled
through the elements IC-1 and IC-2-2 (See FIG. 4B) so that the pulses
supplied through the clock gate 30 (that is, elements IC-8-C and IC-9-C)
are again counted and stored. Each room digit is similarly counted and
stored and held for presentation to the printer.
The logic circuitry for columns 5 and 6 which are to print the status
symbols derived from the last digit dialed is somewhat different. As
indicated previously, the particular printer utilizes a seven segment
print format, in that the seven segments define the number 8. In the
illustrated arrangement, a binary 8 is hard wired to columns 5 and 6
inputs to activate all seven segments. In order to achieve print-out of
alpha characters as previously described, it is necessary to over-ride the
printer's logic to effect turn-off of selected ones of the seven segments.
The alpha conversion logic 46 for performing this function includes a
digit recoder 46 D to receive binary signals (from storage counter section
IC-6-A) representative of the last dialed digit that corresponds to the
status code. Outputs from the digit decoder 46 D are fed through a set of
alpha gates 46 G, each of which connects to a separate segment gate 46 S
which, in turn, are connected to the segment driver logic within the
printer to over-ride selected printer segment drivers and cause the
printer to produce the desired two letter status symbol in response to a
single dialed digit. The digit decoder 46 D is shown at IC-7 in FIG. 4B;
its outputs being connected to a set of alpha gates identified as IC-12,
IC-13 and IC-14, each of which operates through a separate section of
segment gate IC-18.
With reference to the alpha conversion logic shown in FIG. 4B, the digit
decoder 46 D or IC-7 is a dual one four type and serves to decode the
status digit stored in the section IC-6-A into one of a plurality of
signals, each of which corresponds to one of the pre-determined status
conditions for which the unit is wired. In FIG. 4B, only three status
conditions are shown in the wiring. These corresponding to the room
status, but additional conditions can be wired to provide for the
restaurant status symbols or other functions.
As indicated previously, the actual printing sequence occurs in response to
the user completing the dialing sequence and hanging up the handset, the
print command signal being transmitted through the print command gate 31
defined by the element IC-12 of FIG. 4A. During the actual print cycle,
one-half of the digit decoder IC-7 is enabled by the printer through
select wire 5 S when it is ready to print column 5. The other half of the
decoder is enabled through select wire 6 S for column 6. Thus, the alpha
signals appear at the inputs of the printer only when the printer is ready
to print the alpha status characters in order to avoid interfacing with
columns 1 to 4.
In instances where the area telephones are identified by only two digit or
three digit room numbers rather than four digits, only the necessary
number of digit storage counters are connected to be enabled from the
digit enable counter. For example, in a two digit room number system, the
storage counters in column positions one and two would be enabled while
the counters in column positions three and four would not be enabled. This
is effected by re-connecting the third enable lead that is normally
associated with the third dialed digit so that it feeds the storage
counter section corresponding to column positions 5 and 6. In such a
situation, the paper tape print-out would contain a two digit room number,
two blank columns and the double character status code.
The particular printer model includes internal circuitry IC-2-T which is
connected through line 22 L to actuate the tone generator 22 for aobut
1/3rd second during the actual printing sequence; thus indicating the
entering of a new status condition.
Also, after the user hangs up, the busy indicator light 24 on the front
panel is turned off in response to de-energization of B and C as shown at
T-H in FIG. 2. The light 24, as shown in FIG. 4A, is turned off by IC-13-A
and Q1.
Where the system of FIG. 2 is to also perform the additional functions of
recording restaurant charges, the cashier would access the unit through
the same PABX trunk and dial the number of the guest room in the sequence
just described but then would dial the special status code digit 7 (orR)
in order to indicate the restaurant charge function by symbol CG. Thus, a
charge code detector 32 is connected to the output of the alpha digit
decoder 46 D to respond only to the binary combination that represents the
charge code digit R. The charge code detector 32 is connected to actuate
the print command gate 31 to cause the printer to print even though the
cashier did not hang up after dialing the charge code digit R.
During the print sequence, the room number and code CG are printed and the
cashier hears an audible tone triggered by the circuit IC-2-T within the
printer. As shown in FIG. 2, the charge code detector also triggers a
reset counter timer 33 to clear the digit enable counter 28 through digit
clock gate 27 and to reset digit storage counter 29 through pulse clock
gate 30. The reset timer 33 is set to provide the printer sufficient time
to print the stored room number and charge code before the counter
information is reset. When the timer circuit 33 clears the counters, it is
then effective to activate a decimal point enable gate 34 which is
connected to a pre-existing input on the printer to cause a decimal point
to appear between the second and third digits of the next entry to be
printed. Thus, when the cashier dials in the four digit dollar amount
followed by a food or liquor code, this data is printed out in the manner
previously described when the cashier hangs up the handset.
As shown in FIGS. 2 and 4A, the normal/busy switch 25 or the printer
end-of-paper terminal are connected to an OR gate 35 (FIG. 2) which is
shown as CR-1 and CR-2 in FIG. 4A to trigger an optical coupler 36 (FIG.
2) which is shown at IC-16 in FIG. 4A. The coupler 36 energizes the trunk
C relay to make the trunk busy.
PREFERRED EMBODIMENT
Referring to FIG. 5, it will be noted that the functional block diagram for
the preferred embodiment includes many components identical to those
appearing in the embodiment shown in FIG. 2. Such corresponding components
are identified by identical reference characters. The preferred embodiment
includes a number of additional features and improvements which are
highlighted by providing dotted line enclosures around the additional
components. In addition, the preferred embodiment requires only four wires
for connection to the telephone PABX trunk so that it minimizes
installation labor and material costs. In the case of the interface
circuitry, the contact bounce eliminator IC-15 is replaced in the
preferred embodiment by an interface circuit designated generally at 115
which is connected to a wire pair that transmits the A relay contact
closures to the electronic signalling unit. The A signal passes unchanged
through a line polarity reversing circuit 115 R to the primary side of an
impedance matching transformer 115 T which couples the A signal to an
optical coupler 115 A which provides isolation between the PABX relay
contacts and the integrated circuit logic of the electronic signalling
system. The output wave form from the coupler 115 A is synchronized with
the opening and closing of the A relay contact and thus generates a wave
form like that shown at A-1 in FIG. 3. The optical coupler 115 A is
connected to activate a timer 115 B which stays energized for the duration
of the call to produce a wave form like that shown at B-1 in FIG. 3 which
is a duplicate in function of the trunk B relay contact previously
described.
When connected to a rotary dial telephone system, the output of optical
coupler 115 A will be of the form of A-1 in FIG. 3. When connected to a
tone dial telephone system, the output of optical coupler 115 A will
follow the A contact closure pattern as determined by the dial tones
acting on the trunk.
Thus, the rotary dial system is considered first. Outputs from the optical
coupler 115 A and from the timer 115 B are connected to a gate 115 AB,
typically a NAND gate and an inverter to trigger a timer 115 C when B-1 is
energized and A-1 opens. If A-1 continues to pulse at the conventional
telephone dial pulse rate, 115 B responds to this to maintain B-1
energized, and timer 115 C responds to A-1 through 115 AB to maintain C-1
energized for generating the wave form shown at C-1 in FIG. 3. Thus, the
elements 115 A, 115 B and 115 C respond only to A signals but are arranged
to present A-1, B-1 and C-1 signals of the same form as described in
connection with the embodiment of FIG. 2.
Thus, the optical coupler 115 A has the sole function of presenting a clean
signal corresponding to the A relay closures. The timer 115 B functions as
a generator for the B-1 signal in that the action of its time delay
creates a B-1 signal duplicating the B-1 trunk signal providing the A-1
input indicates the trunk is still seized. The timer 115 C functions as a
generator for the C-1 signal when supplied with the correct A-1, B-1
signals.
In the preferred embodiment of FIG. 5, the output circuitry includes a
disconnect timer 37 which is connected to respond to the output from the
timer or generator 115 B and which is connected to control the line
polarity reversing circuit 115 R in order to command the telephone PABX
trunk to disconnect the calling party after the elapse of a specified time
interval (30-45 seconds) during which the user fails to dial in the room
data. Thus, the disconnect timer 37 functions to prevent the system from
being inadvertently tied up by someone failing to hang-up the telephone
handset. Line polarity reversal is a common telephone signalling means and
is used here merely to signal the PABX trunk to disconnect the user who
has failed to hang-up.
An important practical feature of the preferred embodiment is that its
circuitry is universal in that it allows the signalling system to respond
either to push button tone dial phones or to the rotary dial pulse phones.
It is sufficient to note that where rotary dial phones are used in
conjunction with the FIG. 5 embodiment, the signal pattern produced at
elements 115 A, B and C feeds logic elements 27, 27 A, 28, 29 and 30
identical to those previously described in connection with the embodiment
of FIG. 2 and the signal conversion storage and recording occurs in the
same fashion as already described.
When the signalling system is used in conjunction with a push button tone
type dialing system, the input circuitry 27 still receives an A contact
closure signal from the PABX when the user dials the access digit and
causes the trunk to seize the electronic signalling system. The optical
coupler 115 A and the timer 115 B generate the A-1 and B-1 signals, but
since A relay in the tone dialing system does not pulse, no C signal is
generated except on hang-up.
In the tone dialing sequence, the audio tones are coupled through the
impedance matching transformer 115 T to a tone dial digit decoder 38 which
functions to detect and convert the correct audio tones into a binary
number corresponding to the digit that was tone-dialed. In addition, the
tone dial digit decoder circuits generate a valid digit signal V.sub.d on
line 38 L only when valid telephone tone dial signals corresponding to a
dialed digit are detected. This signal is fed to the input gate 27 to
condition the logic circuitry to respond to subsequent dial signals to
serve the same function as the C-1 signals of the previous embodiment in
that the valid digit signal indicates that a digit is being dialed.
Thus, the logic circuitry still has the required three input signals --A-1,
B-1 and V.sub.d which replaces and corresponds to the C-1 signal. The
hang-up sequence which previously generated a C-1 signal still produces a
C-1 signal from gate 115 AB and timer 115 C. Gate 115 AB derived the C-1
signal in that A-1 output from the coupler 115 A de-energizes before B-1
output from the timer 115 B as indicated at T-H in FIG. 3. Thus, the print
command signal is transmitted from 115 C to the print command gate 31 to
actuate the printer 11.
Since the digit storage counter 29 in the preferred embodiment is required
to respond either to dial pulse or tone dial signals, it uses integrated
circuit binary counters that may be preset or loaded directly with a
binary number or clocked to a particular binary number. If the signalling
system is connected to a rotary dial telephone system, the sections of the
storage counter 29 are enabled, in turn, by the digit enable counter 28
and clocked to the correct binary number by clock pulse gate 20 in
response to pulsing of the A-1 signal. The digit enable counter 28 is
advanced by each digit clock pulse from gate 27.
If the signalling system is connected to tone dialing equipment, the
decoder 38 detects the tones, generates V.sub.d on line 38 L and generates
the correct binary number. This number is fed to the preset inputs of the
digit storage counter 29. The leading edge of signal V.sub.d loads this
number into the storage counter section that is enabled by digit enable
counter 28. The trailing edge of signal V.sub.d triggers the digit clock
gate 27 to produce a digit clock pulse that advances the counter 28 to the
next count. The circuits are now ready to accept new tones to be decoded
and loaded into the next enabled storage counter section.
A memory 39 is included so that room numbers which fall into certain status
categories may be stored, as they are dialed into the signalling system
for future recall by the motel clerk. For example, if the digit decoder 30
D signals a room's status as being clean CL, it signals the memory control
40 to store the room's number and status as it is being printed on the
paper tape. At some later time, the desk clerk operates front panel
controls (not shown) to signal the memory control 40 over line 40 L to
provide a summary print-out of all rooms that are clean as stored in the
memory. Line 40 L is connected through OR gate 35 to optical coupler 36 to
make the PABX busy so that no one may call during the print-out. A room's
status in memory may be changed by simply dialing in the room number and
its new status. Each room number has a unique location in memory along
with its current status. The memory control 40 through gate 41 generates
the print commands for the summary pri | | |
