US 3636553 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent [151 3,636,553 Hancock 1 Jan. 18, 1972 541 ALPHA-NUMERIC DISPLAY SYSTEM 2,481,269 9/1949 Welch ..340 339 89 8 m1 We 19 Hancock, 107 Sycamore, 330333 851328 .340/339 Mesa 8520 3,493,957 2/1970 Brooks ..340/339 x  Filed: Jan. 21, 1969 Primary ExaminerDavid L. Trafton PP N94 792,436 Att0rneyEdwin M. Thomas 52 US. Cl ..340/336, 340/339, 340 343  ABSTRACT  Int. Cl. ..G08b /36 A changeable neon sign employs a series of symbol display  Field of Search ..340/339, 336, 343, 324 modules, each of which is made up of a matrix of glow tubes; the individual elements which can be activated to produce any  References Cit d selected letter or numeral are caused to glow in the desired arrangement. A series of such modules is controlled to come on UNITED STATES PATENTS in desired sequence by a solid-state switching system which in turn is programmed by a tape control or reader system. The 3,387,269 6/1968 Hernan et al ..340/324 R X switching System, including a hift register, can present the 3432846 3/1969 f et "340,324 R X input data as traveling copy. A digital input code can present 3,505,672 4/1970 Chisholm 340/324 R X other dam 1,718,499 6/1929 Thomas 340/343 H X 2,123,459 7/1938 Andersen ..340/339 X 11 Claims, 7 Drawing Figures 44 45 5 A-c STROBE If 3 t F :fiij. i
i 381%,, STEP A-C ON A-C DISPLAY I I DISPLAY DRIVE OFF CONTROL MATRIX MATRIX l 11 I l r s STEP s I d 53 2,155 I l 77 L: SHIFT u SHIFT T LEADER T oscooen s 4 ENCODER I fig'GllSTER T se lsTeR f i l 8* l T 1 9i 48 1 4s 46 59 tLj' to H JL i,
COMMA l 3 semlcoLgg H ;;3 8 ggg 39 L sane 4 LATCH M I SHIFT gl DRIVER 757 COLON RELEASE SPEED UP v.75
HOLD FLASH CLOCK INHIBIT CLOCK DISPLAY LOAD TRAVEL TIME OPERATE SPEED i l S 66 83 7| minnows-n 3,836,553
SHEET 1 OF 4 HG. 1 r fi INV TOR, BRUCE JAY HANCOC LL 721w ATTORNEY PATENTED .mn 81972 sum u or 4 FIG.
\SECOND SHIFT FIRST SHIFT -|N|T|AL POSITION FT TIME Ac now I I PERIOD A-C "ON PERIOD M5 :c 100 MS I'NVENTOR. F 7 BRUCE JAY HANCOCK ATTORNEY ALPHA-NUMERIC DISPLAY SYSTEM BACKGROUND OF THE INVENTION Activated signs of various types have been designed in the past to attract the attention of viewers and to convey messages to the public. Many schemes have been proposed to present animated or moving letter or word arrangements on an electric sign wherein the displayed information can be selectively changed or controlled. Electric signs of this general type commonly employ a row of universal or monogram letters, each of which comprises a matrix of individual lamps or gasfilled e.g., neon) tubes which can be selectively lighted in various combinations to form any of the letters of the alphabet, or numerals, punctuation marks, and other symbols. Signs of this type have been mounted on billboards or buildings. They can be fastened to the underside of the wings of an aircraft, or carried on other kinds of mobile vehicles for advertising or other communication purposes. In some instances the displayed infonnation is statically lighted to show a word or phrase and remains lighted as long as desired. In other instances the monogram letters may be automatically controlled so as to ap pear to move from right to left in a manner described as a traveling message. Typical of the prior art means designed to accomplish the functions mentioned are those disclosed in US. Pat. Nos. 2,290,261 and 2,583,184.
While many of the more complex and changeable electric signs of the prior art have met with public acceptance, the best of them often have been difficult to service and maintain because of their inherent complexity. This is particularly true of the traveling message signs which, generally speaking, have been made up of incandescent lights rather than neon and analogous glow tubes. The use of complex mechanically operated switching systems has not only adversely affected the reliability of many of the prior devices, but has also significantly restricted their versatility.
SUMMARY OF THE INVENTION Many shortcomings and limitations of prior activated sign devices are overcome by the present invention which employs a novel combination of neon sign elements, grouped into modules or universal units to display any desired character, together with solid-state logic and control circuitry to automatically sequence and control the operation of a plurality of the improved modules-or display matrices. All of the individual letter display matrices or modules as they are referred to herein, for convenience, are of like construction. Each of them is provided with an associated control means or shift register whereby a letter or character-forming code stored therein may be shifted to the next register and matrix to the left. In this way data transmitted to the first matrix may thereafter be shifted to the next adjacent matrix, and so on.
A further and particular improvement of the present invention is designed to permit fractional space shifts which improves continuity and readability of a traveling message sign. Other apparatus features of this invention also permit a greater degree of flexibility of operation, as compared with prior devices of the same general class. Means are provided for producing selectively a choice or a combination of (I) traveling messages, (2) copy changes, and (3) flash modes of operation. All of these are under control of a master record, preferably a perforated tape of the type produced on a standard teletype machine. However, magnetic tapes and other recorded control devices may be used instead of the perforated tape, if desired. Modular construction of the logic and control elements, according to this invention, helps to obtain both economy of manufacture and greater reliability.
Other features, advantages and objects of the invention will become apparent from consideration of a description of preferred embodiment, referred to in the following drawings and description.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of a universal letter matrix made up of a plurality of glow tubes, of the type used in the invention.
FIG. 2 is a simplified block diagram of a preferred embodiment of the invention.
FIG. 3 comprises a detailed block diagram of the control portion of the apparatus of FIG. 2.
FIG. 4 is a schematic circuit diagram of the shift register module employed in the apparatus of FIG. 2.
FIG. 5 is a front view of a modified system wherein fractional width modules or matrices are arranged for fractional width shiftings.
FIG. 6 shows diagrammatically the fractional shift system.
FIG. 7 shows a control arrangement for the system of FIGS. 5 and 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1 there is shown a module or matrix unit containing various gas-filled tubes. These tubes are arranged to make up a universal letter display matrix, indicated generally by the numeral 1. There are 30 separate tube segments indicated at 2 through 31 respectively. Each of these tube segments or elements is filled with a gas suitable for producing light, such as neon, and is provided with energizing electrodes at each end in a manner well known to those skilled in the art of luminous electric signs. The tube elements (2-31) meet at their ends or, in some cases they may cross each other at various angles. These elements are of various lengths and configurations, as clearly shown in FIG. 1. All of the tubes comprising the universal letter matrix 1 are electrically connected in series by suitable interconnecting leads, typical ones of which are indicated at 32 and 33. A plurality of externally accessible terminals (e.g., 36 and 37) connect to corresponding ones of the interconnecting leads, except in the single instance of lead 33 which interconnects the two tube segments 10 and 11 which are used to form the letter V."
Terminals 34 and 35 are provided to connect the matrix 1 to a high-voltage power supply (to be described more fully in connection with FIG. 2). The power supply, of course, energizes each of the series-connected element 231, causing them to glow. However, each tube element may be short-circuited, selectively, by means of an external shunt placed across a corresponding pair of the externally accessible terminals. For example, terminals 36 and 37 may be shunted in order to black out tube segment 5. The shunt circuit, which is external to the tube assembly, may be closed by means of a remotely actuated relay, i.e., of reed switches, etc., as will be described hereinafter. In order to form a desired symbol or letter, all of these tube elements (2-31) which are not to be used in forming the letter are short circuited by their respective reed relay contacts. Thereby they are, of course, blacked out. Obviously, there will remain in the energized series circuit only those tube elements which are required to form the desired letter.
Each of the tube elements 2-31 is secured to a plastic mounting tray 38 by any suitable and well known fastening means. This tray is preferably black faced and may be formed by vacuum molding, or by extrusion or pressing, or in any suitable manner. A plurality of mounted display matrices of the type shown in FIG. I are arranged in a planar side-by-side relationship. The total number of matrices used is determined by the length of the message which is to be displayed at any given time. In a typical construction, 10 to 20 of such matrices may be placed in a row. In response to the control system to be described hereinafter, any selected number or group of the matrices in the row may be appropriately lighted to display a word, phrase, etc.
The letters of the message may be caused to move from right to left so as to form a traveling message, if desired, or the entire bank of letters may appear stationary for a certain length of time after which the control system relights the bank with a repeat or with a new message, as desired. Successive messages may be presented, alternated, repeated in cycles, or given in any desired series or sequence, as limited only by the capacity of the control record, such as a perforated tape used to provide an input to the control system. This latter mode of operation is referred to as the copy change" mode.
Still another mode of operation, under the automatic control of the input tape or equivalent record, may cause the message to be repeatedly flashed through the display matrices, in place, for a selected number of times after which a new message may be flashed onto the display bank. If desired, all the various modes of operation may be interchanged in any desired sequence, all under the control of the input tape or record.
The high-voltage supply used to energize the series-connected glow tubes (2-31) is not applied, according to one feature of the invention, until all of the selected reed relay contacts have been closed. This provides a so-called dry-contact switching which greatly extends the life of the switch contacts.
In FIG. 2 there is shown a simplified block diagram of the system used to program and energize the above-described display matrices automatically. Except as otherwise noted hereinafter, the various blocks shown in FIG. 2 comprise conventional and well known devices for performing their respective functions; therefore, it is deemed unnecessary to illustrate their circuit details. Where required, circuit details will be described hereinafter to the extent that appears to be necessary to permit those skilled in the art to practice the invention. The invention will be described in connection with use of a teletype perforated tape control, but it will be understood that other records, such as magnetic tape and equivalent devices may be used, as will readily be understood by those skilled in the art.
The message to be displayed is first encoded in a standard seven-bit teletype code, represented fragmentarily at 42. This is recorded on a perforated paper tape 41 by a conventional teletype or equivalent perforator. The paper tape 41 is read via a seven-channel tape-reader 43, the step-by-step advancement of which is under the control of a pulse train appearing on line 44 from an appropriate tape motor drive 45. The teletype code output carried on line 46 is converted by means of diode-matrix decoder 47 to an intermediate code transmitted on line 49. The output of 47 thus is supplied to an encoder 48 which, in turn, reencodes the data into code suitable for controlling the sign. In this specific case a 29-bit parallel-line code is provided, being suitable to drive the reed relays which shunt the neon tube elements comprising any one of the matrices l. The 29-bit parallel-line code on line 51 from encoder 48 drives a first shift register 52, the features of which will be described in a subsequent part of this specification, relating to FIG. 4.
The first alpha-numeric display matrix 1, identified as 53 in this figure and of the type already described in connection with FIG. 1, is controlled by the No. 1 shift register 52. The combination of the display matrix 53 and the shift register 52 makes up a letter display module shown by the larger dotted line box 39. There are a plurality of identical letter display modules arranged in a row so as to permit a complete message or message phrase to be displayed. Only two display modules 39 and 55 are shown in FIG. 2, in the interests of clarity and simplicity. It should be understood, however, that any desired number of modules may be connected in cascade. The data stored in the first shift register 52 is automatically transferred into the second shift register 54 in the second letter display module 55, whenever a new code is transferred from encoder 48 to the first shift register 52. With additional units, not shown, it will be understood that the operation will follow the same principles.
All of the display matrices (e.g., 53, 56) are energized simultaneously with high-voltage alternating current obtained from an AC control 57 via conductor means or bus 58. The AC control 57, in a typical construction, may include a highvoltage transformer of the type conventionally employed for lighting neon and analogous glow gas signs. The voltage applied to the primary winding is nominally about I10 to I20 volts, e.g., ll7 volts AC, and the voltage appearing at the secondary, on bus 58, is about 5 kilovolts in a specific example. The AC control 57 performs a power switching function in response to On and Off control signals appearing on lines 59 and 62, respectively.
In addition to providing the letters of the message which is to be displayed, the data coded in the punched tape 41 also controls the mode of display. Teletype codes for certain punctuation marks are used for mode control and comprise the comma colon and semicolon They are used to perform the respective functions of 1) rapid travel of input tape prior to the copy change mode, (2) initiation of the copy change" mode, and (3) initiation of the flash mode. In the absence of a comma, colon, or semicolon code perforated in the tape 41, the system will operate in the travel mode, which is the normal mode of operation. A selected character signal, say a comma command is used to precede a message phrase in the copy change mode and results in the appearance of a control signal on a line 62 going to a copy change latch 63. When the copy change latch 63 is open, a signal will appear on line 61 which, in addition to turning off the AC control 57 (thereby turning off the display matrices 53 and 56 while the phrase is being read into the system), also speeds up the clock 72. This permits the message phrase to be rapidly entered. At the end of the phrase, another control signal, e.g., a colon will appear in the tape and cause a hold command signal to be sent to the hold and flash control 64 via line 65.
If the flash mode is to be used, then one or more semicolons can be entered in the tape 41 at the end of the message phrase. The number of semicolons determines the number of times the message phrase will be flashed. The flash signal appears on line 66 from the decoder 47, and controls the hold and flash control 64. The flash rate, that is, the time that the neon tubes in matrices 53 and 56 remained lighted, is determined by the setting of a potentiometer 67 associated with a manual display time control device 68.
The speed of travel of the message, shifting of information codes from module to module, (e.g., from module 39 to module 55), and other command and regulating functions are controlled by the clock 72 mentioned above. The rate of the clock may be manually adjusted by a front panel travel speed control 71. This control 71 comprises a potentiometer 73 which is coupled to the clock 72 via line 74. The clock 72 pulse train appears on a line 75 and is supplied directly to the shift pulse driver 76. The output from shift pulse driver 76 appears on a bus 77 which is supplied as a step pulse to the tape motor drive 45. This output also serves as the shift pulse for the several shift registers (e.g., 52, 54).
The step pulse on line 77, in addition to synchronizing the tape motor drive 45, also generates an AC strobe signal on line 78. The AC ON signal on line 59, plus the AC strobe signal on line 78, drive a gate in the AC control 57, thereby causing energization of the high-voltage supply bus 58 or conductor means for lighting the tube matrices 53 and 56. This, of course, takes place after the alpha-numeric code has been set up in the shift registers 52 and 54. In this way the clock 72 synchronizes the application of the high-voltage to the display matrices 53 and 56. The clock 72 therefore is controlled by three different input signals, namely the copy change" signal on line 61, the hold duration" or clock inhibit signal on line 79, and the travel speed signal on line 74.
The output of the copy change latch 63 which appears on line 61 is used to speed up the pulse repetition rate of clock 72, whenever the copy change latch 63 is in its copy change" or open condition. At the same time, the AC power to the display matrices 53 and 56 will be turned off so that the input information may be transferred rapidly from one module to another until all of the modules are filled with the predetermined information. Then, the presence of a semicolon encoded in the tape 41 will stop the clock 72 (by the appearance of signals on lines 66 and 79) and turn on the AC high voltage so that the message can be displayed. The semicolon signal appears on line 66, which supplies an input to the hold and flash control 64. A pulse output from the hold and flash control 64, appearing on line 81, comprises a latch release signal to reset the copy change latch 63 to its Off or closed condition. The operation of the clock 72 is inhibited whenever a pulse appears on line 79. The advancement of the tape reader 43 may be inhibited by closing switch 82 which is part of a manually operated load-operate control 33. Whatever message is being displayed at the time the load-operate control 83 is activated, will remain displayed.
After each semicolon is read from the tape 41, and the flash interval has elapsed, the tape is advanced one step under control of the signal appearing on line 59 from the hold and flash control 64 to the tape motor drive 45.
If a colon (z) is sensed by the tape reader 43, then a signal will appear on line 65 and set the hold control 64. This in turn will generate a clock inhibit pulse on line 79 leading to clock 72, and hold the then-existing message being displayed for an interval determined by the manual setting of the display time dwell-time control 67-68. At the completionof this interval, the clock 72 will revert to its normal pulse rate.
The shift pulse appearing on bus 77 performs the function of shifting the 29-bit code from module to module, but it is a data strobe" pulse which transfers the 29-bit code from the encoder 48 to the first display module 39 in the bank of modules. This data strobe pulse is synchronized with the shift pulse on bus 77 and is derived from the shift pulse driver 76 via line 84. The output of the data strobe driver 85 appears on line 86 which connects to the encoder 48. The 29-bit code in shift register 52 controls a plurality of reed relay contacts which in turn short out the unused tube segments in the matrix 53. This interconnection is indicated by line 88. The transfer of the 29-bit code in shift register 52 to the next shift register 54, in response to a shift pulse on bus 77, is via line 87. The 29-bit code in shift register 54 controls matrix 56 by the interconnections represented by line 89.
Successive numbers of display modules may be connected in cascade to lines 58, 77 and 91.
In FIG. 3 there is shown a more detailed block or schematic diagram of the control logic portion of the system of FIG. 2. In this diagram the hold and flash control device 64, of FIG. 2, has been expanded by showing it as a composite of two separate blocks, namely, the hold control 92 and the flash control 93. Also, the AC control 57 of FIG. 2 is shown in FIGS. 3A and 38 as an AC drive gate 94.
The advance period is initiated, in the specific example being described, by the appearance of a comma encoded in the tape. When decoded by the decoder (see 47 in FIG. 2) a pulse will appear on line 62 leading to the copy latch 63. This will produce a l state on line 61 and speed up the clock 72 so as to rapidly read in the data from the tape. An operate-set signal on a line 97 leading to the copy latch, or a set signal on line 81 (generated in response to a color signal on line 65) will change the output state of the copy latch to the 0 or operate state. When the hold control 92 is in the l state, the signal on line 99 will inhibit the operation of the clock 72 and thereby hold the display of the message. This will prevent the transfer of new data into the shift registers 52, etc. An operate or l state of the flash control 93 will set the copy latch via line 95.
The AC drive gate 94, FIG. 3, comprises a three-input unit which is responsive to the simultaneous occurrence of operate or 0 state signals on lines 95, 98 and 106 to produce an output on the AC bus 58.
The duration of the interval during which the message may be displayed in the copy change mode, is controlled by a copy change potentiometer 101, which is connected to the hold control 92 via a line 102. The output of the clock 72, on line 75, is amplified by the shift pulse driver 76 and is applied via line 103 to the data strobe 85. The data strobe output on line 86 advances the encoded data from encoder 48 (see FIG. 2) into the first shift register 52.
An output pulse on line 105 synchronizes the operation of the hold control 92 with the flash control 93, and the operation of the tape drive 45 synchronizes the application of AC to the matrices via the pulse on line 106.
There is shown in FIG. 4 a schematic circuit diagram of a typical section of the shift register which corresponds to block 52 in the apparatus of FIG. 2. In practice there are a total of thirty bit storage sections in each shift register and display module, one section for each of the tube elements 2 to 31 which make up each display matrix 1 (e.g., matrix 53 of FIG. 2). For clarity and simplicity, only two of these bit storage sections are shown in FIG. 4. It will be understood that the other 28 sections are connected in cascade in the same manner as that shown by way of example for the first two.
Tube elements 2 and 3 in FIG. 4, are connected in series via a lead 32, and are supplied with high-voltage AC from the bus 58 or conductor via a terminal 34. Reed switches or relay contacts 111 and 112 are shunted across the tube element 2. The next-following memory or bit storage section is identical to the first and has like parts which are identified with like numbers plus the addition of a prime notation. Thus, tube element 3 is shunted with reed relay contacts 111' and 112'. An operating potential (about 12 volts DC) is supplied to the positive terminal 118 and the ground terminal 119. The parallel line code signal (from line 51 in FIG. 2) is applied to a terminal 114 and the shift pulse input is applied to terminal 65. The positive-going data (code) input pulse at terminal 114 passes through a diode 116 during the strobe interval and stores a positive charge on a memory capacitor 121. During the strobe interval a shift transistor 126 in a cathode circuit 125 of a silicon-controlled rectifier (SCR) 124 will be turned off by the shift pulse. Transistor 126 is normally turned on (conducting) until the shift pulse appears at the terminal 65 and turns it off during the shift interval. This negative-going shift pulse is applied to the base of the transistor 126 via a resistor 127 and a checking diode 122. Resistor 128 is connected between the base of the transistor 126 and ground 119.
The shift and data strobe pulses occur simultaneously. When the shift transistor 126 is turned off by the shift pulse, it will turn off the SCR 124 and deenergize the primary winding 123 of the reed relay. This will open contacts 111 and 112. If the relay had been previously energized when the SCR is turned off, the collapsing field in the primary winding 123 will induce a pulse in the secondary winding 132. This induced pulse will feed through the input diode 116 to memory capacitor 121, in the next bit, via the interconnection of line 133 from terminal 134. The charge on capacitor 121' will hold since there is no available discharge path until after cessation of the shift pulse and transistor 126' is turned back on.
When the shift pulse on bus 77 terminates, a discharge path for capacitor 121 will be provided through the diode 117, thence to gate electrode and on through the SCR, thereby turning it on.
If the relay primary winding 123 had not been energized at the inception of the strobe interval, then there would have been no storage pulse propagated from the secondary winding 132 and the second SCR (115', 124, and would not be turned on.
The network comprising the resistor 129 and the capacitor 131, connected between gate 115 and the cathode 125 of the SCR 124 is utilized to eliminate stray radiofrequency impulses or transient signals which might turn on the SCR.
The above-described shift register transfer action can be extended to other memory sections in the chain.
The high-voltage power used to light the tube elements 2 to 31 is not applied to the bus 58 until all of the memory units have reached a post-transfer steady-state condition.
In summary, the operation of the shift register and memory unit is as follows: Upon command from the control unit, the encoder data are transferred to the first display module and turn on appropriate ones of the 30 SCR's. These, in turn, latch the corresponding reed relays in the memory units to short out their related segments of the series-connected neon tubes in the display matrix. To transfer the stored data pattern in the first module 39 to the second module 55, FIG. 2, requires only that a shift pulse appear on bus 77 while a pulse is propagated from the secondary of the previously latched relay to the storage capacitor of the next-following bit storage section of the shift register.
Referring now to FIGS. 5, 6 and 7, the system there shown operates more or less in the same manner, except that it has special utility and advantages for displaying information in the traveling message format, while still retaining all the advantages of the system already described. It is somewhat more complex, but the traveling message runs much more smoothly and is easier to read.
In general, this system employs a system of half modules," of which two are normally used to display each full character, such as a letter of the alphabet, an arabic numeral, etc. These half modules each operate independently, just as the full modules with complete characters in a matrix 1, of the embodiment of FIGS. 1 to 4 operate. The most important advantage of the half module system is that it can be shifted, character by character, from right to left, in three very shorttimed steps. The visual effect is that flicker and jumping, which characterize the full module system to some extent, are largely eliminated. The characters seem to come into being and flow like a smooth stream along the sign or screen, with no or almost no perceptible flashing on and off or jumping.
As shown in FIG. 5, each half module or matrix 201 is made up of 21 tube elements 202 to 222 (as compared with 30 in FIG. 1). An appropriate backing is provided for each half module. Each such half-sized matrix is wired in essentially the same manner as the full matrix 1 of FIG. 1 and each is connected to a corresponding set of bits and circuits as described in connection with FIG. 4.
Each half module or matrix is made half the width of a full character and equal to the width of a space between characters. Space wise, then, it will be seen that three half modules, without any space between them, occupy the same lateral space width as a full module plus an accompanying space in the system of FIGS. 1 to 4. To shift a character to the left by a full character space then requires three half-module shifts. This is shown diagrammatically in FIG. 6 when the letter C is shown as moving in successive steps to a new character positron.
The system is wired and clocked so that the actual shift or Off period for each half module is extremely short, e.g., half a cycle or less of standard 60-cycle current (e.g., in U.S.A.) or 50-cycle in countries where the latter is standard. That is to say, that the actual shift time is 1/120 or 1/100 second or less. In lighting a character 200 and shifting it from X to Y, FIG. 6, the first two modules, at the beginning of the message, are lighted. The third one, representing a space, is dark. The first two remain on for a suitable time period, say 0.05 to 0.5 seconds, then the circuit shifts the same character to the second and third half modules, the first going dark. This shift, or time dark, is less than 0.01 second, as explained above. The first half module does not come on but represents a space so the character has shifted one-third of a unit to the left. This is repeated, lighting the third and fourth half modules, allowing the second half module to remain dark. Half a new character, spaced from the shifted character, now appears and at the next shift, the first and second half modules are lighted with a new character, the fourth and fifth modules show the shifted original character, and the third half module, which remains dark for this step, represents space between them.
In order to accomplish this shift without substantial flicker, the transfer or dark time is very short as compared to the standing or on time for any given character. By moving the characters in short steps, and keeping the light on almost continuously, they appear to come into being and to flow smoothly across the sign without perceptible flash or flicker. The effect is a much more readable sign, largely free from the factors which in the past have given eye strain.
The voltage pattern for moving the characters is represented graphically in FIG. 7 where the relatively long on time and short shift time indicates the substantially continuous nature of the traveling message.
By reducing the number of elements in a (half) module to 21 as compared with 30 in a full module, tube requirements are 63 per character, as compared to 30 or slightly more than double. However, the visual advantages, freedom from jump and flicker, are so great that this moderate increase in cost and complexity is well justified, where the traveling message is to be used to any substantial extent.
It will be understood that the other modes of operation such as copy change and/or new message after a desired number of repeated showings, etc, are as applicable to the system of FIGS. 5, 6, and 7 as to those of the system of FIGS. I to 4. The half-module system permits selection from 42 instead of 30 tube elements for production of any given character. This makes the characters clearer and more distinct, in many instances, than is possible when they are produced from single matrices, as in FIG. 1. The heavy lines in FIG. 6 show how some of the characters are produced from two half matrices.
From the foregoing it will be seen that there is provided by the present invention a novel and improved control system for the selective energization of the components of an electric sign having a plurality of tandem-connected display modules. Various modifications have already been suggested but these and other modifications, changes, and omissions may be made by those versed in the art without departing from the spirit of the invention and all these are considered to be within the scope of the following claims except as they are necessarily limited by the prior art.
What is claimed is:
l. A symbol display system, comprising:
a. a source of operating potential,
b. a plurality of universal display matrices each having a relatively large number of illuminable elements each adapted to be selectively and separately illuminated in response to an input signal and upon the application of operating potential thereto from said source, a primary decoding means for receiving data in bits of smaller total number than the number of illuminable elements in each of said display matrices and for decoding said data,
d. means for shifting the decoded data to an encoder, in-
cluding means for adapting the data from the primary decoding means to control of said larger number of illuminable elements;
e. an encoder adapted to receive signals from the decoder and encode new signals;
f. the control means for said illuminable elements including a selectively operable switch means shunted across each of said elements,
g. a plurality of digital shift registers for storing signals received from the encoder, the first of said shift registers being connected to the first of said display matrices and adapted to shift the stored signals to a subsequent shift register connected to a second display matrix in cascade relationship on receipt of new data signals from the encoder;
h. transfer control means connected in common to said shift registers for transferring the encoded combination of signals in each register to the next succeeding register and display matrix, and
i. switching means connected in common to all said display matrices for supplying operating potential thereto from said operating potential source after the selected shunt switches have been set in their required and respective open or closed positions.
2. A display system according to claim 1 wherein said source of operating potential comprises a selectively energized alternating-current power transformer, the secondary of which is connected across said series-connected tube segments via said switching means.
3. A display system according to claim 1 wherein said digital input means includes:
a perforated-tape reader, responsive to data digitally recorded in an input tape for generating a first digital code; and
means for converting said first digital code to a parallel-line code, the number of lines of which corresponds to the number of tube elements comprising said display matrix.
4. A display system according to claim 1 wherein said shunt means comprises:
a plurality of reed relays each being associated with a corresponding one of said tube elements, and each having a pair of reed contacts shunted across the end terminals of the associated tube element, and each of said relays having a primary and a secondary coil; and
means for energizing and deenergizing the primary coil of the first of said relays in response to said control signals and thereby propagate a transfer signal in the secondary coil thereof.
5. A display system according to claim 4 wherein said shift registers each comprise:
a silicon-controlled rectifier connected to said primary coil;
a transistor switch connected to said silicon-controlled rectifier for controlling conduction therethrough in response to the operation of said digital input means.
6. A display system according to claim 1 including:
clock means connected in common to said sift registers, said digital input means, said transfer control means. and said switching means for synchronization thereof.
7. A display system according to claim 1 including:
means responsive to a recorded traveling message code for cyclically transferring the encoded combination in each of said display matrices to the adjacent one of said display matrices.
8. A display system according to claim 1 including:
record means and means responsive to a copy change code on said record to sequentially inhibit said switching means and said transfer control means.
9. A display system according to claim 1 including:
record means responsive to a recorded flash code to selectively inhibit said transfer control means.
10. A display system according to claim 1 wherein a plurality of partial matrices are arranged to display a single composite character.
11. A display system according to claim 1 which comprises a series of partial matrices each adapted to display part of a single character, and means for shifting illumination from a given partial matrix to an adjacent matrix to shift illuminated characters only a partial character space per shift.