United States Patent
`Flanagan et al.
`
`-
`
`<
`
`3,675,513
`[15]
`[45] July 11, 1972
`
`Reddel............................... 179/84 UF
`3,581,283 5/1971
`[54] COMMUNICATIONS SYSTEM FOR
`3,405,234 10/1968 West................................., 340/171 R
`ALPHANUMERIC INFORMATION
`3,582,554 6/1971 Le Blang............................ 179/84 UF
`EMPLOYING AUDIO TONE
`3,381,276 4/1968 James.................................. 179/2 DP
`2,073,333 3/1937 Chireix.................................... 178/25
`SIGNALLING
`3,557,311
`1/1971
`Goldstein.....
`... 17.9/2 DP
`[72] Inventors: James Loton Flanagan, Warren; James
`3,536,839 10/1970 Prins.........
`... I 79/2 DP
`Hughes Kronmeyer, Jersey City; John
`3,213,441 10/1965 Shook.................................... 340/336
`Richard Nelson, Somerville, all of N.J.
`2,200,807 4/1940 Potts..….
`----------- 340/354
`[73] Assignee: Bell Telepl
`Lal
`ted,
`Murray Hill. Berkel º 3,292,178 12/1966 Magnuski.
`... 179/15 BM
`y Hill, Berkeley Heignts, N.J.
`2,645,771 7/1953 Labin................................ | 79/15 BM
`July 24, 1970
`[22] Filed:
`-
`[21] Appl. No.: 58,074
`
`Primary Examiner—Kathleen H. Claffy
`Assistant Examiner—David L. Stewart
`Attorney—Guenther: R. J. and William L. Keefauver
`[52] U.S. Cl. ........................................ 179/84 VF, 179/2DP
`[57]
`ABSTRACT
`[51] Int. Cl........................................................ H04m 11/00
`[58] *:º i 79.2 pp. i º *: º: 3. #. A communications system for exchanging alphanumeric infor
`340/336 337 343 354 171 R I? I A. | 7 | pf
`mation between remote stations, employing station apparatus
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`(e.g., modified typewriters) capable of generating and
`responding to an audio tone code. The system is compatible
`with use of a push-button telephone instrument as an alterna
`References Cited
`tive sending station.
`UNITED STATES PATENTS
`3,472,965 10/1969
`Blossom............................. 340/171 R
`11 Claims, 12 Drawing Figures
`
`[56]
`
`OTHER SENDERS AND/OR
`SENDER RECEIVERS
`
`
`
`
`
`MODIF|EO
`TYPEWRITER
`
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`
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`
`TWO-WIRE
`COMMUNICATIONS
`SWITCHING
`SYSTEM
`
`MODIFIED
`TYPEWRITER
`
`28
`
`SIGNAL
`DECODER
`
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`DISPLAY
`UNIT
`PUSH-BUTTON]- 39
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`
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`
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`
`GOOGLE EX. 1025
`
`Google v. Philips
`
`

`
`PATENTEDJUL1 1 ma
`
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`GOOGLE EX. 1025
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`Google v. Philips
`
`GOOGLE EX. 1025
`
`Google v. Philips
`
`
`
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`

`
`PATENTEDJUL 11 I972
`
`3.675.513
`
`SHEET 2 or 9
`
`ALPHANUMERIC
`CHARACTER
`
`FIG. 2
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`GOOGLE EX. 1025
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`Google v. Philips
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`GOOGLE EX. 1025
`
`Google v. Philips
`
`

`
`PATENTED JUL 1 1 07?
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`3, S75,513
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`Google v. Philips
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`PUENTEDJUL1 1
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`I972
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`3,675,513
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`GOOGLE EX. 1025
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`Google v. Philips
`
`GOOGLE EX. 1025
`
`Google v. Philips
`
`

`
`PATENTED JUL 11 §7.
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`3, 675,513
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`GOOGLE EX. 1025
`
`Google v. Philips
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`

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`PATENTE).JUL 11 §72
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`3,675,513
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`GOOGLE EX. 1025
`
`Google v. Philips
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`

`
`PATENTEDJUL 1 1
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`GOOGLE EX. 1025
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`Google v. Philips
`
`GOOGLE EX. 1025
`
`Google v. Philips
`
`

`
`PATENTEDJUL 11 I872
`
`3.675.513
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`sum 8 or 9
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`PATENTED JUL | 1 ||72
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`3, 675,913
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`Google v. Philips
`
`

`
`3,675,513
`
`10
`
`15
`
`1
`2
`COMMUNICATIONS.SYSTEM FOR ALPHIANUMERIC
`ments of a wide variety of users; one which can take advantage
`of the general availability of the telephone network and
`INFORMATION EMPLOYING AUDIO TONE
`telephone equipment for shorter messages but which is also
`SIGNALLING
`compatible with and can be upgraded to an efficient tele
`BACKGROUND OF THE INVENTION
`typewriter communications system suitable for transmission of
`longer messages between relatively fixed locations,
`l, Field of the Invention
`It is therefore an object of this invention to provide a flexi
`This invention relates to communications systems for
`ble system for communicating alphanumeric information.
`exchanging alphanumeric information between remote sta
`It is a more particular object of this invention to provide ap
`tions and more particularly to a communications system with
`paratus for sending and receiving messages transmitted in an
`the capabilities of a teletypewriter system wherein the
`signalling employed is such that an ordinary push-button
`audio tone code compatible with use of a push-button
`telephone as an alternative sending station.
`telephone instrument may be used as an alternative sending
`Another object of this invention is to provide a typewriter
`station.
`to-typewriter communications system employing audio tone
`2. Description of the Prior Art
`signalling.
`It has long been recognized that the push-button telephone
`Yet another object of this invention is to provide a
`set is a communications instrument of potential application
`typewriter-to-typewriter communications system employing
`other than for conventional voice communications. It has
`an audio tone code compatible with use of a push-button
`been suggested that the audio tones generated within such a
`telephone as an alternative sending station.
`telephone instrument be used as a means for remote computer
`20
`A further object of this invention is to provide an inexpen
`access (see, for example, “A Pushbutton Telephone for
`sive teletypewriter communications system.
`Alphanumeric Input,” Leon Davidson, Datamation, Vol. 12,
`No. 4, April, 1966, p. 27 et seq.). Others have proposed aug
`SUMMARY OF THE INVENTION
`menting the telephone instrument with alphanumeric visual
`display apparatus responsive to alphanumeric information
`These and other objects of this invention are accomplished,
`transmitted from the dial of another push-button telephone to
`in accordance with the principles of this invention, by provid
`provide an entirely visual mode of telephone communication
`ing apparatus for automatically coding messages, typed on the
`(see, for example, “Ring Two – For Tomorrow”, M. W.
`keyboard of a modified typewriter, in an audio tone code
`Nabut, Electronics World, Vol. 79, No. 2, Feb. 1968, p. 46 et
`which can alternatively be generated using the dial of a stan
`seq.). All of these proposals seek to take advantage of the
`30
`dard 12-button, push-button telephone set. More particularly,
`presently wide and potentially universal use of push-button
`each of the keys of a sending typewriter is equipped with a
`telephone instruments. When, in the not too distant future,
`microswitch which is operated when the attached typewriter
`push-button telephone sets become standard telephone equip
`key is depressed. Operation of any of these microswitches trig
`ment, they will be widely available potential coding and send
`gers apparatus which selects the audio tones associated with
`ing stations for alphanumeric data and information.
`the typed typewriter function and pulses the selected tones in
`Perhaps the most obvious deficiency of the push-button
`a manner appropriate to the coding of that function.
`telephone “dial” as a coding device is the fact that for any in
`At a receiving station the audio tones are identified and the
`formation other than strictly numeric information the user of
`pulses counted by decoding apparatus, also constructed in ac
`the device must learn and use a code more complicated than
`cordance with the principles of this invention, in order to
`40
`the simple one-for-one coding employed for sending numbers
`determine which typewriter function is being received. If the
`(e.g., telephone numbers). Even the simplest of alphanumeric
`receiving station includes a typewriter, the identified function
`coding schemes requires the sequential depressions of two or
`is implemented on that typewriter by activation of a solenoid
`more buttons to code any character other than a number. In
`which pecks at or depresses the appropriate typewriter key.
`addition, since the message must be transmitted character by
`Alternatively, the receiving station may include any of several
`character by the manual operation of the telephone push-but
`other types of visual display apparatus similarly activated by
`tons, considerable time is required when messages of substan
`the decoding device.
`tial length are to be sent.
`The audio tones chosen for this system are compatible with
`In any scheme for communication by push-button
`those used in standard push-button telephone systems. In ad
`telephone dial coding, apparatus for the decoding and display
`dition, the code employed may be easily implemented by
`of transmitted information must be attached to the receiving
`means of manual operation of a push-button telephone dial.
`station. Unless, however, that apparatus is capable of making
`Finally, the decoding apparatus is such that synchronization of
`a permanent record of information received, the receiving sta
`sending and receiving apparatus is not required and timing is
`tion must be attended by a person capable of receiving the
`not material. Thus, information sent from either a sending
`message, Similarly, unless recording apparatus is attached to
`typewriter or a push-button telephone can be decoded equally
`the sender's telephone, he has no way of verifying or recording
`well.
`information transmitted.
`Further features and objects of this invention, its nature,
`Quite obviously, the needs of the several users of a commu
`and various advantages, will be more apparent upon con
`nications system such as this will vary. Some users may require
`sideration of the attached drawings and the following detailed
`rapid communication of fairly lengthy messages between fixed
`description.
`locations. For these users, a requirement of extra equipment
`at each of the fixed locations is no hardship, albeit cost is an
`BRIEF DESCRIPTION OF THE DRAWING
`important consideration. Others may require the input to a
`fixed location of relatively short messages from many, con
`FIG. 1 is a block diagram of the communications system of
`stantly changing locations. For these, extra equipment at the
`this invention showing the various kinds of apparatus which
`65
`may be compatibly interconnected;
`central location is not a problem if unadorned telephone ap
`FIG. 2 is a coding scheme for use with the system of FIG. 1;
`paratus can be used at the remote locations. Still other users
`FIGS. 3A through 3D, which are to be read together as
`may require a communications system employing a combina
`shown in FIG, 3E, comprise a schematic diagram of the auto
`tion of the above features. Even the needs of a given user may
`matic coding apparatus of this invention;
`change from time to time, there being a need at some times for
`70
`a rapid, efficient means of transmitting long messages between
`FIGS. 4A and 4B, which are to be read together as shown in
`FIG. 4C, comprise a schematic diagram of the automatic
`fixed locations, while at other times short messages must be
`decoding apparatus of this invention;
`transmitted from changing locations.
`Accordingly, there exists a need for an alphanumeric com
`FIG. 5 is a schematic diagram showing how the apparatus of
`FIG. 3 may be modified to generate a coding sequence dif
`munications system with the flexibility to meet the require
`75
`
`50
`
`25
`
`35
`
`45
`
`55
`
`GOOGLE EX. 1025
`
`Google v. Philips
`
`

`
`10
`
`15
`
`45
`
`3,675,513
`3
`4
`ferent in kind from those generated by the apparatus of FIG.
`may take place between them in very much the way tele
`3; and
`typewriter communication is usually accomplished, i.e., with
`FIG. 6 is a schematic diagram showing how the apparatus of
`coding and decoding being automatic and the users being con
`FIG. 4 may be modified to decode the coding sequence
`cerned only with the operation of their respective terminals
`generated by the apparatus of FIG. 5.
`primarily as typewriters. As will be seen from later discussion,
`however, these fully automated terminals may be used to
`DETAILED DESCRIPTION OF THE INVENTION
`receive messages not only from other automated terminals but
`As is now well known, the depression of any given button on
`also from terminals like terminal 16 whereat message coding is
`done manually.
`the dial of a standard 12-button, push-button telephone instru
`ment causes the instrument to generate one of 12 pairs of
`Alternatively, a less elaborate and less expensive sender
`audio tones whereby the button depressed may be identified.
`receiver 14 may be constructed using a push-button telephone
`The 12 distinctive tone pairs are combinations of seven audio
`set, a decoder similar to that required in sender-receivers 10
`tones, each pair comprising one tone from a low range of
`and 12, and a visual display unit. In a sender-receiver of this
`frequencies (i.e., 697 Hz., 770 Hz., 852 Hz., or 941 Hz.) and
`type, push-button telephone set 30 is used as a manual coding
`one tone from a high range (i.e., 1209 Hz., 1336 Hz, or 1477
`device while messages are received and decoded automati
`cally by decoder 26 and displayed on visual display unit 28.
`Hz.). As is also familiar, the 12 buttons on such a dial are
`Visual display unit 28 may be a typewriter similar to
`marked 1 through 9, 0, *, and # . In addition, the letters of
`typewriters 22 but modified less extensively or, if a permanent
`the alphabet, with the exception of Q and Z, are associated in
`record of messages received is not required, display unit 28
`groups of three with buttons 2 through 9 by additional
`20
`markings on the dial.
`may be any alphanumeric character display light tube unit.
`The apparatus of this invention is also suitable for remote
`An easily remembered alphanumeric code which takes ad
`communication with computer devices. In applications requir
`vantage of the customary arrangement of and markings on the
`ing such communication, the computer may be connected to
`standard push-button telephone dial is shown in FIG. 2. Two
`the system of FIG. 1 in any well-known manner. For example,
`coding modes are employed to subdivide the character set and
`25
`a computer access terminal may be used in lieu of visual dis
`to simplify coding. In the first or “numeric” mode, the ten
`play apparatus 28 in sender-receiver station 14.
`digits (i.e., 1 through 9 and 0) are coded just as any digit in a
`numeric telephone number is customarily coded, i.e., by the
`Attention will now be focused on the details of the construc
`tion of each of the components of the system generally
`momentary depression of the appropriate button. In the
`described above.
`30
`second or “alphabetic” mode each of the 26 letters of the
`FIGS. 3A through 3D depict a suitable automatic signal en
`alphabet is coded by one, two, or three pushes of an assigned
`coder, denoted signal encoder 24 in FIG, 1, and show how it
`button followed by a single push of a button (i.e., the 0-but
`may be connected to the keyboard 34 (FIGS. 3A, 3B, and 3C)
`ton) assigned to an “end-of-code” or “print” function. The as
`of a modified typewriter, denoted modified typewriter 22 in
`signment of buttons to alphabetic characters is such that max
`35
`FIG. 1. Each of the character and function keys on keyboard
`imum use is made of the markings universally found on push
`34 is arranged to operate a single-pole, double-throw
`button telephone dials. Thus A, the first letter associated with
`microswitch as well as the usual typewriter mechanism when it
`the 2-button, is coded by a single push of the 2-button fol
`is depressed. These microswitches are arranged so that a first
`lowed by a single push of the 0-button. Similarly, B and C, the
`connection (to a vertical lead 35) is maintained while the as
`second and third letters associated with the 2-button, are
`40
`sociated typewriter key is in the normal position and a second
`coded by two and three pushes, respectively, of the 2-button
`connection (to a horizontal bus 37 or 71) is made when the
`followed by a single push of the 0-button. For coding pur
`key is fully depressed. These microswitches may be mechani
`poses, Q and Z may be assigned the first and second positions
`cally connected to any convenient part of the key mechanism
`on the 1-button.
`of the typewriter in a conventional manner.
`If this scheme is continued, there remain several unused
`When the typewriter key for any of the typewriter opera
`codes. These are the third position on the 1-button and three
`tions or functions coded as shown in FIG. 2 is depressed, the
`positions each on the *-button and the 4 -button. These may
`breaking of the so-called first connection in the microswitch
`be used for the coding of necessary punctuation marks (e.g.,
`for that key changes signal conditions at one of the input ter
`the period and comma), function controls (e.g., typewriter
`minals of the OR gate 38 (FIGS. 3A, 3B, and 3C) associated
`space and carriage return), coding mode control (e.g., numer
`50
`with the push-button telephone dial digit or symbol required
`ic or alphabetic), and the like. In addition, as will be discussed
`to code the typed function. This may be accomplished, for ex
`below, more coding sequences can be made available if button
`ample, by having all of the input terminals of the OR gate con
`operations are intermixed. The code illustration in FIG. 2 is
`nected to ground through the so-called first connections of the
`therefore a convenient, easily remembered method for coding
`microswitches for the group of functions to be coded by pulses
`alphanumeric information on a push-button telephone dial.
`of the tone pair for the given dial digit or symbol. The OR gate
`FIG. 1 illustrates a highly flexible alphanumeric communi
`for which a connection is thus broken produces an output
`cations system employing the coding scheme of FIG. 2 which
`signal which triggers one of pulse formers 40 (FIGS. 3A, 3B,
`can be constructed, according to the principles of this inven
`and 3C). Triggered pulse former 40, which may conveniently
`tion, to utilize the facilities of an ordinary telephone commu
`be a Schmitt trigger device, amplifies and makes more precise
`nications network. Particularly desirable is a telephone net
`the signal applied to it. The output signal of the triggered pulse
`work in which 12-button, push-button telephone station sets
`former in turn activates one of the digit or symbol select
`are widely employed. As shown in FIG. 1, several types of
`devices 44 (FIGS. 3A, 3B, and 3C), which may be a bistable
`communications apparatus may be compatibly connected to
`multivibrator. The activated multivibrator applies enabling
`any two wire telephone switching system 20 for purposes of
`signals by way of diodes 46 to the pair of AND gates 48 as
`alphanumeric communication as described herein. In addition
`sociated with the audio tone generators 50 (FIGS 3A and 3B)
`to 12-button, push-button telephone sets 30, any one of which
`capable of generating the pair of audio tones used to signal the
`may be used as a send-only station (e.g., station 16), sender
`appropriate push-button telephone dial digit or symbol.
`receivers of several kinds may be employed. Apparatus 10, for
`Diodes 46 serve to isolate digit select devices 44 from one
`example, is a sender-receiver comprising a modified
`70
`another by allowing current flow in only one direction. It
`typewriter 22, a signal encoder 24, and a signal decoder 26, all
`should be noted that no audio tones are produced by tone
`arranged as discussed in detail below. Sender-receiver 10 is
`generators 50 until additional drive or control signals,
`therefore a communications device with many of the capabili
`generated as described hereafter, are applied to the other ter
`ties of the usual teletypewriter terminal. When two such sta
`minals of enabled AND gates 48. Audio tone generators 50
`tions (e.g., stations 10 and 12) are connected, communication 75 may be any suitable audio oscillator circuits, for example,
`
`55
`
`65
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`4:20
`
`GOOGLE EX. 1025
`
`Google v. Philips
`
`

`
`
`
`5
`
`10
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`15
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`25
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`30
`
`35
`
`3,675,513
`5
`6
`those found in an ordinary 12-button, push-button telephone
`37–3. Pulse formers 54 (similar to pulse former 72), mark
`instrument (see, for example, U. S. Pat. No. 3,184,554 issued
`one-shot devices 56 (similar to one-shot device 74), and space
`to L. A. Meacham et alon May 18, 1965).
`one-shot devices 58 (similar to one-shot device 78), all shown
`In addition to enabling AND gates 48, signals from select
`in FIG. 3D, comprise a cascade of units for producing one,
`devices 44 may also be applied by way of diodes 92 (FIGS.
`two, or three mark pulses separated by short time intervals.
`3A, 3B, and 3C) and bus 93 to keyboard lock device 94 (FIG.
`These mark pulses are applied by way of diodes 62 (FIG. 3D)
`3C). Keyboard lock 94 may be any of several types of
`to AND gates 48 with the result that one, two, or three short
`mechanical or electrical inhibitors available on many electric
`bursts of the pair of audio tones for the appropriate digit or
`typewriters to prevent or nullify the depression of a typewriter
`symbol are generated by two of audio tone generators 50. The
`key while another key is depressed. By controlling keyboard
`number of mark pulses produced by this apparatus depends on
`lock 94 with signals from select devices 44, the depression of
`which of pulse formers 54 is used to trigger this portion of the
`additional typewriter keys will be either prevented or ignored
`apparatus and that in turn depends on which of leads 37 the
`while the coding of a typewriter function is taking place. Al
`initial signal appeared. If, for example, the typed key is one for
`ternatively, keyboard lock may be apparatus for disabling the
`which the second microswitch connection is connected to lead
`keyboard microswitches or preventing their operation from
`37–3, pulse former 54–3 will be activated. This will set off a
`having any effect on the coder. This may be accomplished by
`chain reaction in which all three of mark one-shot devices 56
`disconnecting the keyboard microswitches or by including
`are triggered. If, on the other hand, the typed key is one which
`blocking gates (not shown) in the output leads of those
`results in a signal on lead 37–2, pulse former 54–2 will be ac
`switches. A simple warning light 96 (FIG. 3C) located on the
`tivated. This will set off a shorter chain reaction not including
`20
`typewriter console and arranged to come on whenever a signal
`the activation of pulse former 54–3, mark one-shot 56–3, or
`from one of select devices 44 is present on bus 93 may be used
`space one-shot 58–3. Accordingly, only two mark pulses will
`together with or in place of keyboard locking apparatus 94.
`be generated. Similarly, an initiating signal on lead 37–1 will
`When the activated typewriter key reaches the bottom of its
`result in only one mark pulse being generated as the result of
`travel, the so-called second connection in the attached
`the activation of pulse former 54–1, mark one-shot 56–1, and
`microswitch is made. This produces a signal on horizontal lead
`space one-shot 58–1 only.
`71 (FIGS. 3A, 3B, and 3C) if the typed key is a number, on
`When the last of these one, two, or three mark pulses has
`one of horizontal leads 37–1, 37–2, or 37-3 (FIGS. 3A
`been generated (in all cases by mark one-shot device 56–1), a
`through 3D) if the typed key is a letter, punctuation mark, or
`reset pulse for resetting digit or symbol select devices 44 is
`generated by reset pulse former 68 (similar to reset pulse
`the like, or on horizontal lead 37–S (FIGS. 3C and 3D) in the
`special case that the alphabetic or numeric mode control keys
`former 80) shown in FIG. 3D. Immediately thereafter, print
`have been activated.
`command one-shot device 60 (similar to mark one-shot 56),
`In the case of a number, a signal on lead 71 triggers pulse
`also shown in FIG. 3D, is triggered. This device generates a
`former 72 (FIG. 3A), similar to pulse formers 40, which in
`final mark pulse which both activates digit 0 select device
`turn triggers mark one-shot device 74 (FIG. 3A). Mark one
`44–0 and (as a result of the enabling of AND gates 48–4 and
`shot 74, which may be a monostable multivibrator, produces
`48–6 by signals from device 44–0) pulses audio tone genera
`an output pulse applied by way of diode 76 (FIG. 3A) to the
`tors 50–4 and 50–6 once. The resulting burst of the audio
`above-mentioned remaining input terminals of AND gates 48.
`tones for digit 0 is used at the decoder as an “end-of-code” or
`“print” signal.
`This mark pulse is blocked by all of AND gates 48 with the ex
`ception of the two gates enabled as discussed above. These
`40
`Finally and after a short delay introduced by space one-shot
`two enabled gates pass the mark pulse to the associated pair of
`device 52 (similar to previously described space one-shot
`audio tone generators 50 with the result that a short burst of
`devices), shown in FIG. 3D, reset pulse former 68 is again trig
`two audio tones is produced. These two audio tones are those
`gered and digit and symbol select devices 44 are reset. The ap
`paratus is thereby made ready to encode another typewriter
`required to signal the typed digit. The duration of the mark
`pulse produced by mark one-shot 74 must be sufficient to
`function.
`allow recognition of the resulting audio tones by whatever
`As in the coding of numeric information, mark pulses of 30
`decoding apparatus is employed. It has been found that the
`milliseconds duration spaced apart by approximately 20 mil
`decoding apparatus described later in this specification will
`liseconds have been found adequate for the satisfactory opera
`operate satisfactorily with pulses of about 30 milliseconds du
`tion of the signal decoder described hereafter. Accordingly,
`50
`the time constants of the mark and space one-shot devices
`ration,
`The output signal of mark one-shot device 74 is also applied
`discussed above must be chosen to produce mark and space
`pulses of these durations.
`to space one-shot device 78 (FIG. 3A). This device, which
`There are two remaining operations performed by the ap
`serves to delay the output of mark one-shot 74, may be any
`paratus of FIGS. 3A through 3D. These are the automatic cod
`suitable monostable multivibrator or delay network. The delay
`ing of the alphabetic and numeric mode control signals. As
`introduced by space one-shot device 78 must be long enough
`shown in FIG. 2, the alphabetic mode is signalled by three
`to allow completion of the coding of the number to be sent
`(i.e., the generation of the audio tone pulse produced as
`bursts of the audio tones for the telephone dial symbol ". The
`above). After this delay, space one-shot device 78 triggers
`numeric mode is signalled by three bursts of the audio tones
`for the symbol + . These special codes may therefore be
`reset pulse former 80 (similar to pulse former 72) which
`produces a pulse used to reset all of bistable digit or symbol
`generated in very much the same way that alphabetic mode
`select devices 44. Any such resetting of select devices 44 also
`functions are coded. No final pulse of the digit 0 tones is, how
`ever, required. Accordingly, while the appropriate gates 48
`serves to release keyboard lock device 94 if such apparatus
`has been included. The system is thereby made ready to en
`are enabled in the manner discussed above, a separate triple
`pulser 82 (FIG. 3D), responsive to signals on lead 37–S, is pro
`code the next typewriter function activated.
`65
`vided for generating three sequential mark pulses as is
`If a letter, punctuation mark, or other alphabetic mode
`typewriter function is to be sent, a signal is produced on one of
`required to code these special control functions. Triple pulser
`leads 37–1, 37–2, or 37–3 when the typed key reaches the bot
`82 may be a cascade of mark and space one-shots similar to
`the arrangement of mark one-shots 56 and space one-shots 58.
`tom of its travel and the second connection, so-called, is made
`in the attached microswitch. The lead on which the signal ap
`Space one-shot device 86 (FIG. 3D) is a delay unit which
`70
`produces an output signal for triggering reset pulse former 68
`pears depends on how many pulses, not counting the end-of
`after time sufficient for the operation of triple pulser 82. Ac
`code pulse, are required to code the desired function. The
`cordingly, space one-shot 86 may be similar to previously
`microswitches for functions requiring one pulse are connected
`described space one-shot devices. The triggering of reset pulse
`to lead 37–1, those requiring two pulses are connected to lead
`former 68 resets the symbol select units 44, thereby readying
`37–2, and those requiring three pulses are connected to lead
`
`45
`
`55
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`75
`
`4121
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`GOOGLE EX. 1025
`
`Google v. Philips
`
`

`
`15
`
`3,675,513
`7
`8
`the encoder of FIGS. 3A through 3D for its next coding opera
`Since manual decoding of information transmitted by
`tion.
`means of the above scheme would be inconvenient if not im
`To summarize, the automatic encoder of FIGS. 3A through
`possible, FIGS. 4A and 4B illustrate apparatus (designated
`3D comprises apparatus for performing two functions in
`signal decoder 26 in FIG. 1) designed to perform this task au
`response to signals from typewriter keyboard microswitches.
`tomatically.
`When any key is initially depressed, a pair of audio tone
`In order to interpret information transmitted as above, it is
`generators for generating tones associated with a given push
`first necessary to identify the audio tones received and to
`button dial digit or symbol is selected. When the typewriter
`further identify the telephone dial digit or symbol represented
`key is fully depressed, a sequence of drive or control pulses
`by any pair of tones thus identified. These functions are per
`appropriate to the coding of the typed function is applied to
`10
`formed in the decoder of FIGS. 4A and 4B by audio tone dis
`the selected pair of tone generators. Thereafter, the tone
`criminator and digit or symbol selector 100 (FIG. 4A).
`generator selecting apparatus is reset. In the case of alphabetic
`Responsive to each burst of audio frequency energy received
`character coding, the encoder performs an additional selec
`on line 99, this apparatus produces an output pulse directed to
`tion and pulsing of the tone generators for an end-of-code
`the one of switches 102 associated wi