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`EXHIBIT 1015
`
`EXHIBIT 1015
`
`

`

`[19]
`United States Patent
`[45] Date of Patent: Feb. 12, '1991
`McCullough
`
`[11] Patent Number:
`
`4,992,774
`
`
`
`[54]
`
`[76]
`
`[21]
`
`[22]
`
`[51]
`[52]
`
`[58]
`
`[56]
`
`METHOD FOR POWERING REMOTE
`VISUAL DISPLAYS AND ALLOWING FOR
`DATA EXCHANGE OVER THE SAME WIRE
`PAIR
`
`Inventor: Robert K. McCullough, 8236 E. 7lst
`St., Suite 356, Tulsa, Okla. 74133
`
`Appl. No.: 302,663
`
`Filed:
`
`Jan. 27, 1989
`
`Int. Cl.5 ............................................ H04M 11/04
`U.S. c1. ............................ 340/310 A; 340/310 R;
`340/538; 375/22; 375/23
`Field of Search ............... 340/310 A, 310 R, 538
`340/82506’.825' 17, 825.29, 825.54, 505, 503;
`455/73, 375/22, 23
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,139,737 2/1979 Shimada ......................... 340/310A
`
`4,228,422 10/1980 Perry ......
`340/310 R
`
`4,408,185 10/1983 Rasmussen
`.. 340/825.54
`4,535,401
`8/1985 Penn ............................... 340/825.54
`
`Primary Examiner—Joseph A. Orsino
`Assistant Examiner—Kinfe-Michael Negash
`
`Attorney. Agent, or Firm—Robert R. Keegan
`
`[57]
`
`ABSTRACT
`
`A novel way of powering a remote visual display and
`allowing data interchanges over the same wire pair.
`Such a station may be used for displaying the time,
`paging a person or an advertising message. The wire
`pair that powers a remote visual display also carries the
`electrically encoded message signal.'On the same wire
`pair there is provision for the master message input
`station to exchange data with slave message input sta-
`tions without message collision. Information from an
`input station key pad is captured by the microprocessor
`which converts the message to a serial binary signal.
`This signal drives a power transistor which converts a
`full wave rectified ac. power current to a pulse width
`modulated signal which drives the wire pair connected
`to a remote visual display. The remote visual display
`power supply rectifies these signal pulses for power to
`drive the control circuits and display mechanism (light
`sources or light reflectors) and decodes the pulse width
`for display message information. The master message
`input station uses the time between pulses to exchange
`data with the slave message input stations.
`
`15 Claims, 6 Drawing Sheets
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`US. Patent
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`Feb. 12, 1991
`
`Sheet 4 of 6
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`4,992,774
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`US. Patent
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`Feb. 12, 1991
`
`Sheet 6 of 6
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`

`1
`
`4,992,774
`
`METHOD FOR POWERING REMOTE VISUAL
`DISPLAYS AND ALLOWING FOR DATA
`EXCHANGE OVER THE SAME WIRE PAIR
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to a visual display pag-
`ing system which consist of one or more message input
`stations and one or more illuminated remote visual dis-
`play stations for communicating messages to viewers.
`The present invention more particularly relates to a
`method for providing power and data exchange to a
`remote visual display over the same wire pair, espe-
`cially to a method for sending message data which is
`rectified for power to drive a remote visual display and
`at the same time allowing the master message input
`station to receive message input data from slave input
`message stations connected to the same wire pair. This
`invention allows for a plurality of both input stations
`and output stations. These remote visual display paging
`systems may display either moving or stationary mes-
`sages. There may be one or more slave message input
`stations that convey the message entered in a slave
`message input location to the master message station for
`eventual display on the remote visual display(s). The
`master message input station may store and sequentially
`display several messages or pages.
`It has become more important in recent times to pro-
`vide a simple, easy visual paging system to page a single
`person from a group of people. This person could be
`located in a crowd in an auditorium or in a restaurant or
`in a retail store. This type of visual paging system typi-
`cally has the display located some distance from the
`message input station. In an auditorium or church the
`message input station may be in the sound control room
`or the nursery. The remote visual display is in front of
`the audience. The visual display paging system can be
`used to page a doctor to the phone or a mother to the
`nursery to attend to her child. The remote visual display
`is typically 100 to 400 feet away from the master mes-
`sage input station. In the restaurant application the re-
`mote visual displays may be in several eating areas some
`distance from the food pick-up area where the message
`input station is located. The visual display paging sys-
`tem could be used to page a customer or waitress to the
`food pick-up areas. In a retail store the message input
`station is typically located in a supervisors office while
`the displays are located through out the store and are
`easily visible by the store clerks. Store clerks or security
`personnel may be easily paged. Store systems can range
`up.to 1000 feet between the input message station and
`the remote visual displays located where they can be
`seen by everyone.
`Remote visual displays require both power and signal
`to operate. First, power must be supplied to operate
`both the display mechanism (light sources or light re-
`flectors) and the serial data decoding circuits. Second,
`the serially encoded electrical signal conveying the
`message to be displayed must be supplied from an input
`station, computer or other source. Thirdly, provision
`must be made for data exchange between the master
`message input station and the slave message input sta-
`tions.
`
`The early installations of these displays required one
`wire between the message input station and the remote
`visual display for each visual element or light on the
`message board and one common return wire. The
`power required for the luminaire apparatus was sup-
`
`10
`
`15
`
`20
`
`25
`
`3O
`
`35
`
`40
`
`45
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`50
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`55
`
`60
`
`65
`
`2
`plied through these control wires from the input station.
`The message input station must be connected to the ac
`power line or some source of power. This type installa—
`tion is very expensive and time consuming. A typical
`installation required 15 wires and only displayed two
`numbers. Also, possible damage can result from miswir-
`ing.
`Later developments in the art refined the system to
`require only one wire pair for the power and another
`wire pair for the signal. The serial signal sent by the
`message input station to the remote visual display is
`decoded and applied to the proper luminaire apparatus.
`A—C power must be provided to both the message input
`station and to the remote visual display. Although an
`improvement,
`this required four wires between the
`message input station and the remote visual display.
`Wire expense and the possibility of the installer damag-
`ing the system with mixed up wires during installation is
`a disadvantage. This happens often when the purchaser
`who is not skilled in the art installs his own system such
`as the case with a church. This has the further disadvan-
`tage in that if the power supply wires connect
`to a
`nearby a-c outlet then provision must be made to dis-
`connect the power when the system is not in use. If the
`power wires come from a great distance then there is
`additional expenses because of the power supply wire
`length. The more sophisticated paging systems which
`accommodated one or more slave message input sta-
`tions required a third wire pair for data exchange be-
`tween the master message input station and the slave
`message input stations.
`OBJECTIVE AND SUMMARY OF THE
`INVENTION
`
`The object and novelty of this inventions is to supply
`both low voltage power and signal on the same wire
`pair to the remote visual display part of a visual display
`paging system.
`Another object and novelty of this invention is to
`allow input message data to be interchanged between
`master message input station and slave message input
`stations on the same wire pair that is supplying both low
`voltage power and signal to the remote visual display.
`Another object of this invention is to have the mes-
`sage sent from the master to be displayed on the remote
`visual display also displayed on all the slave message
`input stations at the same time.
`Another object of this invention is to be able to enter
`or delete any message from any master or slave message
`input station.
`A further object and novelty of this invention is a
`method of preventing message collision between the
`remote visual display, the master message input station
`and slave message input stations.
`Another object of this invention is to provide a
`method for making installation easier since there is only
`one wire pair transmitting both power and signal from
`the message input station to the remote visual display.
`This wire pair when connected in a reverse manner will
`not damage the electric message display board. Installa-
`tion is further simplified since only the message input
`station(s) require an a-c electrical outlet.
`A further object of this invention is to provide a
`method to disconnect the power to the remote visual
`display during long periods of non use.
`This invention is embodied in an apparatus for cap-
`turing and displaying messages more particularly for
`
`

`

`4,992,774
`
`3
`visually displaying changing messages on a remote vi-
`sual display.
`The apparatus comprises means for keyboard entry of
`a message, storage of that message in memory, transmis-
`sion of the message and power to the remote visual
`display and data exchange between the master message
`input station and slave message input stations.
`The operator types in a message on the keyboard
`which the microcomputer chip captures and stores in
`memory. The microcomputer converts the message
`stored in memory to a pulse width modulated serial data
`stream to be transmitted to the remote visual display.
`The microcomputer chip drives an emitter follower
`power output transistor which is connected to the re-
`mote visual display. The remote visual display rectifies
`this power pulse and stores this energy in a capacitor
`which supplies power to the decoding control circuits
`and the display mechanism (light sources or light reflec~
`tors). The remote visual display control circuit senses
`the pulse width and decodes this information to deter-
`mine the message to be displayed. Because the data is
`pulsed, the time between pulses is available for data
`exchange between the master message input station and
`the slave message input stations.
`In order to synchronize the serial data streams be-
`tween the master and slave stations and prevent mes-
`sage collision the master sends out a synchronizing
`pulse after each complete pulse data stream of 40 pulses.
`Each slave is assigned a priority position and a time slot
`for a transmission-request bit. If a slave has data to be
`transmitted to the master then it will begin transmission
`after the sync pulse if there are no other slaves with a
`higher priority requesting transmission at the same time.
`When the operator is finished and turns off the power
`to the master input station then the power ceases to be
`transmitted to the remote visual display. This achieves
`the power removal to the remote visual display during
`periods of non use.
`This invention is embodied in an apparatus described
`herein for the purpose of paging mothers from a church
`service to the nursery when they are needed by their
`child. The master message input station is located in the
`nursery and the remote visual display is located in the
`auditorium or sanctuary. When the mother checks her
`baby into the nursery she is given a number. She then
`proceeds to the auditorium and can enjoy the sermon
`knowing that if she is needed by her child in the nursery
`the nursery worker can type in her child’s number. The
`number will immediately appear in the auditorium on
`the remote visual display, whereupon the mother will
`respond by coming to the nursery. When she comes to
`the nursery the worker delets her number from the
`master message input station. For larger churches, one
`or more additional slave input message stations may be
`added in other nurseries. The numbers being displayed
`by the master message input on the remote visual dis-
`play are also picked up and displayed by all the slave
`message input stations on their local display. This al-
`lows a person in another nursery to view all the cur-
`rently displayed numbers. Also any number can be
`added or deleted from any of the slave input stations
`even though it was entered from another message input
`station. The master message input station can drive
`multiple displays and will page up to 7 mothers (num-
`bers) at one time by displaying the numbers sequentially
`for about 3 seconds each. The system has the following
`benefits:
`Easy installation
`
`Multiple displays
`Multiple input stations
`Sequence through up to 7 paging numbers.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 shows an overview of a complete remote
`visual display system.
`FIG. 2 shows in more detail the inner workings of the
`master message input station and the option changes
`necessary to make it a slave message input station.
`FIG. 3 shows the remote visual display overview and
`the method of deriving dc power from the signal sent by
`the master message input station.
`is combined
`FIG. 4 shows how the system signal
`from the master message input station and slave mes-
`sage input station signals using a diode-resistor “or”
`function.
`
`FIG. 5 shows the detailed composite system signal
`pulse requirements.
`FIG. 6 shows the detailed relationship of the pulse
`train on the system signal line. Also described here is a
`method of slave data collision avoidance.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`FIG. 1 shows an overall diagram of the Visual display
`paging system. This consist of a master message input
`station 1 and a remote visual display 2. The master
`message input station also has a local visual display 6 so
`the operator can see what numbers he is entering on the
`key pad 7. The slave message input stations 10 also has
`a local visual display 8 so the current message can be
`viewed until the operator starts to enter a message at
`that slave input station keyboard 9, at which time the
`slave local visual display 8 shows the keys 9 being
`pressed by the operator. The entire system is connected
`on the same wire pair 15. This wire pair carries both
`power and signal to the remote visual displays 2 and
`may or may not carry power to the slave input station
`10. For ease of installation this wire pair 15 is usually,
`but not necessarily, a coaxial cable such as RG59/U.
`The use of coaxial cable prevents the unskilled owner-
`/installer from mixing up the interconnecting wires.
`FIG. 2 is a diagram of the master message input sta-
`tion. The message input ordinarily would come from a
`keypad 7. The microcomputer 20 scans the keypad 7 for
`a series of strokes, which constitutes the message, and
`records these strokes in memory. The ac line voltage
`36 is reduced by transformer 4 down to 24 volts and
`then applied to a bridge rectifier 23. The output of this
`bridge rectifier is not filtered with a capacitor but left in
`the half wave format to allow detection of the zero
`crossing 25 of the a-c line by the microprocessor 20.
`The microcomputer is interrupted by the zero crossing
`of the a-c line voltage 28 and allows the microcomputer
`to synchronize the peak output pulses 101 with the peak
`of the a-c line voltage 26, 43. Thus for each cycle on the
`a-c line there are two pulses output to the remote visual
`display. Therefore, 120 pulses per second are sent to the
`remote visual display.
`The microcomputer 20 arranges the message cap-
`tured from the keyboard 7 into a serial data stream of
`variable width pulses 101.
`In this embodiment each
`pulse is assigned to one particular segment or light on
`the display. In another embodiment these pulses may
`contain the address of a particular element in an array.
`If the pulse is wide then the segment is turned “ON"
`
`10
`
`15
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`20
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`25
`
`30
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`35
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`45
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`50
`
`55
`
`65
`
`

`

`4,992,774
`
`5
`and if the pulse is narrow then the segment is turned
`“OFF".
`
`The low level 5 volt output signal 46 from the mi-
`crocomputer 201’s shifted to the 35 volt driving level by
`transistor 30. When the signal 46 out of the microcom-
`puter 20 is low then transistor 30 is off and the base of
`transistor 33 is pulled high by resistor 32 thus shutting
`off transistor 33 and allowing the output 47 from the
`sending unit to be pulled to ground by resistor 34. When
`the output 46 of the microcomputer 20 is high then
`transistor 30 pulls the base of transistor 33 low and
`transistor 33 pulls it’s collector high which pulls the
`output 47 high. Because the microcomputer is inter-
`rupted 29 by the zero crossing of the a-c line 25 it can
`time the output pulses 47 so that they coincide with the
`peaks of the a-c line 43. During these peaks is the only
`time that power is transferred from a rectifier to a ca-
`pacitor in the ordinary power supply. The time between
`master station output pulses is used for data exchange
`between the master and slave stations FIG. 5 T20.
`A local visual display 6 allows the operator to know
`what they have typed into the keyboard 7. As the mi-
`crocomputer chip 20 recieves data from the keyboard 7
`it arranges it in serial form and shifts it out to the display
`driver 44 which drives the local LED visual display 6.
`The only hardware difference between a master mes-
`sage input station and a slave message input station is
`the position of switch 49 and 50. When in the switch 49
`is the master mode the entire process is synchronized to
`the a-c line. When switch 49 is in the slave mode the
`microcomputer is synchronized to the system signal line
`48 by means of the signal derived from the junction of
`resistors 38 and 39 and the 5 volt'zener diode pulse
`clamp 40. This clamped system signal is connected to
`the microcomputer interrupt line 29 through switch 49
`to allow the software to synchronize to the master mes-
`sage input station. The slave message input station soft-
`ware remains synchronized to the master station by the
`sync pulse FIG. 6 211 on the system signal line FIG. 2
`48. The slave is also able to receive the number cur-
`rently displayed on the remote visual display 2. It then
`displays this number on the local slave display 8 so the
`operator will know what numbers have been entered
`from other stations. The slave station reads what its
`slave number and priority are by means of switch 50.
`When the slave has a message to transmit to the master
`it uses this priority to establish transmission sequence as
`shown in FIG. 6 and described below.
`
`FIG. 3 shows a remote visual display diagram. The
`power for the display is supplied by rectifying the mes-
`sage signal 77 coming from the master message input
`station. This signal is rectified by diode 60 and filtered
`by capacitor 61. This supplies the unregulated power to
`the lamp supply regulator transistor 73. Zener diode 75
`sets the lamp voltage. Transistor 73 regulates the volt-
`age applied to the lamp to 12 volts. This is applied to the
`anode of a series of 5 LED’s 67. When the bit intended
`for that segment (5 LED’s) is high, then the LED driver
`66 pulls low causing current flow through the LED’s 67
`which causes them to light up.
`The data is extracted from the input signal 77 by
`dividing down the system signal from the input lead
`through resistor network 62—63. The negative edge P7
`is used to trigger a one shot timer 64 which produces a
`clock pulse 72. The negative edge triggered timer 64
`triggers when the input signal 71 goes low at P7. This
`timer produces a positive pulse P5 exactly 2.5 millisec-
`onds later. This pulse is used to clock in data from the
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`6
`input pulse 71 to the serial input display driver 65. If the
`signal pulse 71 goes low then returns high at time P5 in
`less than 2 milliseconds then the pulse is considered to
`be “ON” and that lamp is turned on. If the signal pulse
`71 goes low then returns high after 3 milliseconds then
`the pulse (time P6) is considered to be “OFF” and that
`lamp is turned off. The microcomputer 20 encodes each
`pulse with the “on” or “off“ information for one of
`seven segments 82 of each digit 83. The entire pulse
`string between synchronizing pulses is 40 pulses. Four
`digits times seven segments each is 28 pulses and the
`remaining 12 pulses are zeros which have no effect on
`the display but could be used to selectively address
`different displays 84.
`FIG. 4 shows how the system signal 77 is combined
`from the master message input station and slave mes-
`sage input station signals. The master and slave stations
`combine their outputs 101 and 104 in a dioderesistor
`“or” function using diodes 102 and 106. When the out-
`put of the master station goes low T10 then if the slave
`station has data 107 to be placed on the system signal 77,
`line then it will go high 107 for 1 millisecond starting 1
`millisecond after the master station’s output goes low
`T10. The system signal 77 is connected to the remote
`visual display 2. The signal is rectified by diode 60 and
`filtered by capacitor 61 to supply power to the remote
`visual display. The data is provided by dividing down
`the system signal 77 with resistors 62 and 63 to drive the
`control circuits described in FIG. 3.
`FIG. 5 shows the detailed composite system signal
`pulse requirements. The timing on one pulse of the
`system signal
`is described as follows. One complete
`cycle of the system signal
`is 8.33 milliseconds. One
`millisecond T3 is allotted to the remote visual display
`data communication. Another one millisecond time slot
`is allotted to the slave message input station data com-
`munications T2.
`
`The master message input station signal 101 goes low
`T10. This signals the slave message input station to
`prepare for data transmission to the master station. One
`millisecond Tl after the negative edge T10 the slave
`message input station places a one millisecond wide
`pulse T2 on the system signal wire to transmit a “1” to
`the master message input station. If the slave message
`input station is transmitting a “0” then the signal will
`remain low 165 during this time. The master message
`input station samples the system signal wire 1.5 millisec-
`onds T11 after the negative edge T10 and stores in
`memory whether the slave message input station data is
`high or low.
`The one millisecond time period T3 is allotted for
`master message input station data transmission to the
`remote visual display. During this allotted time the
`master message input station places a high signal 152 on
`the system signal output line if the remote visual display
`segment assigned to this pulse is “on“.
`An ordinary bridge rectifier charging a capacitor
`only conducts heavy current during the peak of the a-c
`cycle. This peak or pulse charging current may only last
`for 2 to 3 milliseconds out of every 8.33 millisecond
`cycle. The remote visual display capacitor charging
`parameters are much the same. The master message
`input station output is a transistor switch 33 that turns
`“on” to connect the bridge rectifier 23 to the system
`signal line 45 hence the remote visual display during the
`peak of the a-c charging cycle 26. The charging current
`166 is plotted against the a-c line voltage 26. It can be
`seen that the time between charging peaks T20 is avail-
`
`

`

`7
`able for other data transmission. One of the novelties of
`this invention is to use that time for data exchange. This
`time is used for slave message input station to master
`message input station data transfer T2 and for master
`message input station to remote visual display data
`transfer T3.
`FIG. 6 shows the detailed relationship of the pulse
`train on the system signal line. Also described here is a
`method of slave data collision avoidance. The data
`
`streams are shown flowing from left to right. Time is
`shown increasing to the left. Therefore the first pulse
`out of the system is on the far right. The master message
`input station output 101 is the system clock and all pulse
`are synchronized to its falling edge. The remote visual
`display internal clock 72 pulses are generated by a nega-
`tive edge triggered one shot 64 as described in FIG. 3.
`This clocks in the data to the remote visual display shift
`register, represented by 203 which in FIG. 6 or 65 in
`FIG. 3, stores 35 pulses and the 36th pulse 204 causes it
`to transfer its data to the display. This is more com-
`pletely described in literature about the MM5450 LED
`display driver manufactured by National Semiconduc-
`tor. One complete data stream is 40 bits long 205. Each
`bit is assigned to a particular segment on the display 66.
`The time between the negative edges on the master
`output data pulse 101 is 8.33 milliseconds. After every
`40 data pulses 205 the slave output 104 is synchronized
`to the master output by a sync pulse 211. This sync
`pulse is double wide or 16.7 milliseconds between nega-
`tive edges. The first 8 pulses after the sync pulse 212 are
`reserved for slave transmission request priority during
`time T2 in FIG. 5. Each slave is assigned at the factory
`a number 1 through 7 by means of a slider switch on the
`circuit board FIG. 2 50 inaccessible to the operator.
`This defines the salve number and it’s priority for trans-
`mitting input message data to the master station. If slave
`station 1 and 4 both have a message to transmit to the
`master station in the same 40 bit data stream then they
`each place a data transmission request bit 216 and 217 in
`their appropriate shift register slot 213. Then after the
`8th bit 218 each slave checks to see if any higher prior-
`ity request have been made before they begin transmis-
`sion on bit 9. In this case slave 1 would find no higher
`priority and would proceed to transmit its message 215
`to the master station. However when slave 4 checks the
`priority request it would find slave 1 requesting trans-
`mission 217 and would hold its transmission until the
`next 40 bit cycle. The combined system signal is shown
`at 77.
`I claim:
`
`1. A system for providing both power delivery and
`signal transmission from a master station to a remote
`visual display comprising
`a master station having means for connecting to a
`power source of alternating current, means for
`rectifying the alternating current
`to produce a
`pulse waveform, a keyboard, a microcomputer
`having the keyboard connected for data input
`thereto, means for pulse width modulating said
`pulse waveform with a serial binary signal from
`said microcomputer including a power output tran‘
`sistor means, said microcomputer providing,
`in
`response to keyboard data input, a serial pulse
`width modulated signal from said power output
`transistor means;
`a single wire pair connected to receive the output of
`said power output transistor means; and
`
`10
`
`15
`
`2O
`
`25
`
`3O
`
`35
`
`45
`
`50
`
`55
`
`65
`
`4,992,774
`
`8
`at least one remote station having a visual display and
`a serial
`to parallel shift register with its output
`connected to control said visual display, said shift
`register having an input coupled to said wire pair
`for receiving said serial binary pulse width modu—
`lated signal
`therefrom and for converting such
`signal to drive said visual display, and, in parallel
`with said wire pair, a capacitor charged by said
`modulated signal, said capacitor being connected
`to provide a direct current power source for said
`visual display.
`2. A system according to claim 1 wherein said serial
`pulse width modulated signal from said power output
`transistor means is substantially a square wave varying
`from ground voltage level to a singular voltage level.
`3. A system according to claim 1 wherein said power
`output
`transistor means includes, as
`the last stage
`thereof, an emitter follower.
`4. A system according to claim 1 wherein there is a
`plurality of remote stations connected in parallel to said
`single wire pair.
`5. A communication system'as set forth in claim 1,
`having a plurality of remote stations with visual dis-
`plays, each of said visual displays being effective to
`store energy from said power pulses and being univer-
`sally responsive to pulses provided by the master sta—
`tion.
`
`6. A system according to claim 1 wherein said master
`station includes a local visual display for displaying the
`data input from said keyboard.
`7. A system according to claim 1 further including at
`least one slave message input station each having a
`keyboard, a microcomputer having the keyboard con-
`nected for data input thereto, means for generating a
`serial binary signal modulated under control of said
`microcomputer, and means for transmitting said signal
`over said single wire pair to the microcomputer of said
`master station.
`'
`8. A system according to claim 7 further including
`means for synchronizing said slave message input sta-
`tion to transmit signals to said master station in intervals
`between pulses of said pulse waveform.
`9. A system according to claim 1 wherein said means
`for rectifying said alternating current is a full wave
`rectifier and the repetition frequency of said pulse
`waveform is twice the frequency of said alternating
`current.
`
`10. A system for providing both power delivery and
`signal transmission from a master station to a remote
`visual display comprising
`a master station having means for connecting to a
`power source of alternating current, means for
`rectifying the alternating current
`to produce a
`pulse waveform, a microcomputer with means for
`providing data input thereto, means for pulse width
`modulating said pulse waveform with a serial digi-
`tal signal from said microcomputer including semi-
`conductor power output means, said micromputer,
`in response to data input, causing a serial pulse
`width modulated signal
`to be output from said
`semiconductor power output means;
`a single wire pair connected to receive the output of
`said semiconductor power output means; and
`at least one remote station having a visual display
`means coupled to said wire pair for receiving said
`serial binary pulse width modulated signal there-
`from and for converting such signal to drive said
`visual display, and a capacitor connected to said
`
`

`

`4,992,774
`
`9
`wire pair to be charged by said modulated signal,
`said capacitor being connected to provide a direct
`current power source for said visual display.
`11. A system according to claim 10 wherein said
`serial pulse width modulated signal from said power
`output transistor means is substantially a square wave-
`form.
`
`10
`13. A system according