CA1073204A - Changeable printed alphanumeric display system - Google Patents
Changeable printed alphanumeric display systemInfo
- Publication number
- CA1073204A CA1073204A CA316,422A CA316422A CA1073204A CA 1073204 A CA1073204 A CA 1073204A CA 316422 A CA316422 A CA 316422A CA 1073204 A CA1073204 A CA 1073204A
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- Canada
- Prior art keywords
- tape
- character
- segments
- roller
- display
- Prior art date
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- Expired
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- Displays For Variable Information Using Movable Means (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A changeable alphanumexlc sign with printed characters is disclosed. The sign is universally changeable in the sense that any combination of alphanumeric characters may be displayed by selectively positioning a set of display tapes in each character window. This arrangement minimizes the length of dis-play tapes required. Each tape of a set of tapes is printed on both front and back surfaces with character segments and is connected between a driving roller and a driven roller in a manner to display one front surface segment and one back surface segment at a time. The tape segments which carry the respective character segments are progressively longer from one end of the tape to the other and the set of tape segments which are dis-played together in the window all bear different character segments of the same character so that an entire character is displayed. All tapes in the set are driven in unison to successively present the character segments of each tape in registry with respective window segments. An open-loop posi-tioning system is used to position all sets of tapes concurrently but independently to change the characters of the sign.
A changeable alphanumexlc sign with printed characters is disclosed. The sign is universally changeable in the sense that any combination of alphanumeric characters may be displayed by selectively positioning a set of display tapes in each character window. This arrangement minimizes the length of dis-play tapes required. Each tape of a set of tapes is printed on both front and back surfaces with character segments and is connected between a driving roller and a driven roller in a manner to display one front surface segment and one back surface segment at a time. The tape segments which carry the respective character segments are progressively longer from one end of the tape to the other and the set of tape segments which are dis-played together in the window all bear different character segments of the same character so that an entire character is displayed. All tapes in the set are driven in unison to successively present the character segments of each tape in registry with respective window segments. An open-loop posi-tioning system is used to position all sets of tapes concurrently but independently to change the characters of the sign.
Description
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This application is a divis:ional of Canadian Patent Application Serial No. 245,005, filed February 4, 1976 by Associated Data Concepts.
This invention relates to information displays and particularly to such displays as are capable of presentlng any of a number of alphanumeric displays.
The problem of presenting a readily changeable alphanumeric readout in a small space has been solved in many different fashions, as exempliied by neon-glow-discharge tubes, liquid crystal readouts, solid-state electro-luminescent devices, and the like. Most such arrangements require operating signals which themselves contain most or all of the information to be displayed, and in any case are in general poorly adapted to large scale readouts, such as may be seen readily from a considerable distance. Further, a general problem with light-emitting displays is illegibility when the ambient light level is high. Cpaque displays, in contrast, increase in visi-bility as the ambient light increases.
A need exists for a mechanically sound, readily and quickly change-able and accurate display for such diversified uses as des~ination indicators for buses, advertising signs, indicators of ambient temperature, time o day, and the like.
~0 An object o the present invention is to provide a readily change- -able display device adapted to displaying letters, numerals, words and phrases and the like within the framework of a mechanically sound apparatus.
Another object o the invention is to provide such a device inclu-ding posi~ioning means whereby the display may be selectively changed to any desired configuration~ and is especially well adapted to positioning by automatic devices, particularlythose under computer or mach~ne control.
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~ particular application of the subject invention is in the field of destination signs for transit vehicles such as buses and trains. Such destination signs mus-t be changeable according to the particular route of the vehicle and, in modern day transit systems, each sign must be capable of displaying a - large number of different destination names in alphanumeric form. A typical destination name may require forty or more characters and the sign must be changeable quickly from one name to another. In the past, destination signs have taken the form of a rQller curtain wide enough to accommodate the requisite number of characters and long enough to hold a full set of destinatlon names requlred for a given vehicle. One great dif-ficulty with this type of destination sign is that the roller curtains must be printed with special destination names according - 15 to the route of a particular vehicle or fleet of vehicles. This requires the printing of a large number of different destination signs for a given metropolitan area ~ith attendant high cost.
Furthermore, with long sign curtains, it is difficult and - expensive to provide automatic sign changing systems.
The rollerlcurtain destination sign, despite the ~ .
~ ~ above-mentioned difficulties, has an exceedingly important , attribute, namely, it affords excellent readability despite - . . . .
wlde variatlons in ambient light. Further, it lends itself to ~ large scale dlsplays so the sign can be read from a distance.
; 2~ As alluded to above, the roller curtain destination sign in the :' :
form of an opaque display, is presently preferred for des~ina-tion signs over all other known displays.
-` This invention~seeks to ta~e advantage of the read~
ability of an opaque display and to overcome the difficulties of . 30 the roller curtain destination sign. In general, this is , accomplished by a sign having a plurality of window areas ;
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each of which is adapted to display one alphanumeric character at a time on a set of display tapes; each window area is capable of - selectively displaying any one set of characters by selectively positioning the respective tapes of the set. Thus, a selected S destination name may be displayed by selec-tive positioning of the sets of tapes.
This scheme allows any destination name to be formed and displayed using identical sets of character display tapes - for each character window area. Thus, the same set of character display tapes may be produced in multiple copies to make up a' de,stinatlon sign and the same,destination sign may be used on any route since any destination-name may be formed by the sign.
To make practical this concept of a universal des-tina- , , tion sign, this invention provides a broken-character, broken-word arrangement. The broken-character utilizes plural display tapes to form each character rather than a single tape showing ' all characters in succes'sion; by thls'technique; each tape is ~ ' shortened to a fraction o the length of the single tape.
'~, ' Therefor the wrap-up of the tapes is minimized and the maximum displacement of any tape to form any character is a fraction of , that required in the case of a ,single tape. The broken-word -- -arrangement utilizes the,tapes in each set which are only one - character wide and which are used for only one window area.
~ ' ,The tapes of each set are positionable independently of the ,~ 25 tapes of any other set; this enables the number of character ' ~. . . . . .
~ ' portions disposed along the length'of each tape to be kept at an -, -' absolute minimum (since,the tape is only one character wide and , no pairs or combinations of character portions are involved laterally~. ,This arrangement allows the sets of tapes to be : , - , - . ' displaced simultaneously to form their respective characters.
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According to this lnvention, a changeable display of printed alphanumeric characters is provided which faithfully reproduces each character, one at a time with a minimum of translatory motion required in changing from one character to another. In general, this is accomplished by using a set of display tapes with each tape bearing discrete character segment which are imprinted on both front and back surfaces of the tape. A driving roller is connected with one end of each tape and a driven roller is con-nected with the other end, and the tape is supported for displaying one sur-face segment of the front and the back of each tape in respective segments of each window. The set of surface segments being displayed together in the window all bear different character segments of the same character so that an entire character is displayed. Means are provided for displacing the tapes in unison along their length to successively present the character segments in registry with the respective window segments whereby all ~, characters of the set may be successively displayed. The number of display tapes in the set is equal to one-half the number of character segments.
The surface segments on both surfacec of each tape become progressively longer frol: one end of the tape to the other.
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Further, in accordance with the invention~ faithful reproduction of the characters is provided by means which ensures proper positioning of the character segments within the respective window segments. This is accomplished by placing the character segments on respective surface segments of the tape with the surface segments being progressively longer from one end of the tape to the other to allow for wrap-up of the -tape on the rollers.
Further, the character segments are nonuniformly spaced along the length of the tape so that equal angular displacements of the driving roller causes proper alignment of the character segments in the window segments.
Further, accordinglto the invention, the proper positioning of the character segments is enhanced by relating the roller size to the length of character segments. In particular, the diameter of the rollers should be approximately equal to the length of two character segments.
Further, according to the inve~tion, the display of each character, even though it is a composite of several segments, is produced without dis-tortion. For this purpose the number of character segments is selected so that the horizontal bars of a character may be carried all on one segment and yet be properly located in the character format. Preferably, the number of character segments is eight. Additionally~ distortion between ~0 adjacent segments is minimized by fairing of the character line at the upper and lower extremitles of the segments.
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Further, according to the invention, the driving and driven rollers are disposed in a minimum of space and may be driven by a single input shaft so the rollers move only in unison. This is accomplished by placing the driving roller oE each set behind the display window and the driven roller immediately behind the driving roller with equal size gears on all rollers and meshing with at least one adjacent gear.
A more complete understanding of this invention, as well as that disclosed in application Serial No. 245,005, may be obtained from the follow-ing description, taken with the accompanying drawings in which:
FIGURE 1 is a front view of three display units in accordance with the invention, each exhibiting a different numeral or figure;
FIGURE 2 is a partially cut-away perspective view of a typical embodiment of the inventive display unit;
FIGURES 3a and 3b are respectively the front and back sides of a display tape such as may be used in the device;
FIGURE 4 is a diagrammatic side view of the device showing the winding mode of the display tape on the rollers;
FIGURE 5 is a sectional view showing the detailed construction of :
a slave roller;
FIGURE 6 is a diagrammatic side view showing the inter-meshing coupling means whereby the driving rollers are rotated and showing an ; optional positioning code disc;
FIGURE 7 is a top fragmentary view of the code disc shown in FIGUF~ 6 "
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FIGURE 8 shows'a des-tination sign accordiny to this invention;
FIGUR~ 9 shows a posltioning control system for use in this invention;
FIGURE 10 is a diagrammatic showing of the relative positioning of the character segments on.the tape;
. .FIGURE 11 shows a modification of the invention; and ': FIGURE 12 is a sectional view taken on lines 11~11 '. . of FIGURE 11. 1 ' 10Coming now to FIGURES 2 and 4~ it will be seen that the device comprises an array of display rollers, 1, 2, 3, 4, 5, 6, '.
7, 8, 9, 10, etc., which are arranged in spaced pairs,'1,2; 3,4;
etc., and in which two'adjacent pairs form.groups of four rollers each, such as 1-4 inclusive, 5-8 inclusive, and so forth. Further~
~ 15 m~re, all of the axes of the cylindrical display rollers 1, 2,' 3, ~ ' etc., are in-the same plane so that all of the cylindrlcal'dis -- play rollers are tangent to a display plane, the position of this ;. ' tangent'display.plane-being indicated.in the drawings by those .~ . segments of .the tapes which lie flat on the front of the display , device, as sho~, for example,'in FIGURE'2 by that portion of the ': : .uppermost tape lying between the points indicated as 11,12,13 and ~4.
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.. - It will be apparent from the drawi~gs and in particular from.FIGURES 1 and'2 that those portions of the display tapés ~ ~isible from the outside form an'array of essentiall'y horizon~
1 ~: - . : , 25~ tal segments ~hich may be viewed as a whole,.thus for example' in ~IGURE 2 displaying the letter "A" made up of eight horizontal gment . ' Reverting now to FIGURE 4, this illustrates the fashion~
.' in which the tapes are;wound:on and over their respectlve rollers.
.Each group of four display rollers, 1-4,5-8,9-12, etc., is backed up by a drivinq roller 15,~16~, 17 and 18, and by a slave roller ,: , ~ , . : :. . , ~ . .
32~4 19, 20, 21 and 22. A tape 23 is ~sten~d at one end to the driving roller 15, and after looping over the back of the driving roller is threaded over display rollers 2 and 1 and thence back over driving roller 15 and thence is threaded over display rol-lers 3 and 4 and is finally taken up by slave roller 19, to which ` its opposite end is fastened.
- It will be observed that in passing over display rol-. .lers.l and 2, one face of the tape 23 is exposed to view, where-as when the tape passes over display rollers 3 and 4 the back or reverse side of the same tape is displayed.
- It will be further noted that the next unit in the . stack comprising display roller 5, 6, 7 and 8, driving roller 16 and slave roller 20, has its own tape 24. The same is true for t~e remaining units ln this stack involving drlving rollers 15. ~7 and 18, slave rollers 21 and.22, and tapes 25 and 26 respec-tively. Further, proceeding from the top of the stack downward each succ~ssive driving roller toyether with all the rollers actuated thereby rotates in a sense opposite to that of its . - neighbor next below, for reasons which will appear later.
. 20 . . In the em~odiment shown in the drawings, four units are - shown in a vertical stack. It will be clear that more or fewer . . . .
~ couldibe used in accordance with the nature of the information .~: : - .
~ to be dispIayed. Likewise, FIGURE 1 shows three such four : .
stack arrays in horizontal juxtaposition. This enables the information on each of the three devices to be varied indepen-dently of the others, which in some instances is advantageous,-as for example when various numbers or various words are to be . shown. Clearly, if for example 20 devices are assembled in a horizontal array.and i each device can display each of the 26 letters of the alphabet and the ten digits rom 0 to 9, then . ; . ;any word of up to 20 letters or any digit up to 1 X 102 - 1 .~
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can be displayed at will.
~everting cnce more to the clrawings, the slave rollers 19, 20, 21 and 22 are take-up rollers which serve to wind up, or as the case may be, to unwind the tape when the display is changed. All of the driving rollers 15, 16, 17 and 18 and the slave rollers 19, 20, 21 and 22 are geared together as may be seen from FIGURE 6, and because of the relative sense of rotation of the various rollers this may be done in the extra-ordinarily simple fashion shown in FIGURE 6. Thus, all of the ' . 10 gears are meshed together at their points of contact, which 'i ' leads.to a complete avoidance of any slippage problems which . might otherwise cause'the tapes in a given stack to become .out of phase. As a given tape is wound from its driving roller onto its slave roll'er, or contrariwise, it will be clear that a . 15. given.amount of angular rotation will correspond to a.slightly .i~ . i ."
~ - varying linear payout or uptake because of the finite thickness : . of the wound tape. We compensate for this slight disparity in . the required angular rotation between a given driving roller and ~ .its slave roller by providing a spring loading in torque for ~ 20 each slave roller, as may be seen from FIGURE 5. It will be , .~ - , . . .
.~ ' . clear from .that drawing that the gear 27 does ~ot drive the '~ roller 19 directly and positively but only through the inter-mediary of a helical spring 28, which is set so as to impart a . moderate degree of tension in the tape. Spring 28 is engaged at one end to endpiece 29 forming part of the slave rol~er 19;.
whereias at the other end it engages anchor pin 30 which.is .
'`'~ . fixedly attached to the-drive shaft 31 which in turn is fixedly .
attached to gear wheel ~27. A stop pin 32 is attached to end-: piece 49 of slave roller'l9, and serves to limit the rotation : 30 of shaft 31 with respect to slave roller 19. It serves to hold the spring 28 from being overstressed during operation if ' .. , . .................... ~ .:
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~73~04 the tape or roller should stick. The arrange~nent of course is repeated ~or each unit in the stack.
It will be clear from the foregoing and particularly, from FIGURE 2, that the array of gears attached to the driving rollers are not only intermeshed with each other, but are also intermeshed with the array of gears which are attached to the slave rollers, and both arrays are intermeshed so that all o the gears may only rotate in unison,'taking into account the opposite senses of rotation of adjacent gears. Thus each driving roller gear engagés at least one other driving roller gear as well as its corresponding slave roller gear; and the same may be said for each of the slave roller gears, each one of these engaging at least one other slave roller gear while at the same time engaging its corresponding driving gear.
., Turning for the moment to FIGURES 3a and 3b, these show respectively the front and back sides of tape 23, which as .
will be appreciated from the foregoing explanation has, ~ , depending upon ,the particular setting of the device, a segment of one side displayed between display rollers 1 and 2, and another segment fro~ the other side displayed between the '~
display rollérs 3 and 4. FIGURE 1 shows the setting of the de-vice so as to display the letter "A". In FIGURE 3a, that segment forming the top half of the upper one-quar,ter of the let-.
' ter,"A" is indicated by 33; whereas that portion of the reverse ' of the tape shown on FIGURE 3 b which forms the lower half of ~ . .
', the uppermost one-qu'arter of th,e letter i'A" is indicated by 34.
, The tape shown in FIGURES 3a and 3b bears sufficient markings ~, to form the upper'one-quarter'portion~ that is, between rollers 1 and 4, ,of all 26 letters of the alphabet, all ten digits from .
, ~ 30 0 through 9, a period,(.?,'a dash (-), a slash ~), and a blank space., ` ~ ~ ' -10--, ~ : .
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~732(~ -t It may be remarked that ~or con~enience in explaining . our invention we-have shown the various rollers as horizontal, I with the stacking vertical; but the terms "horizontal" and i "yertical" are used mainly for convenience. It is self-evident that the entire apparatus shown may be rotated through 90, so that the rollers will then be vertically disposed. Obvio~s changes will then have to be made in.the arrangement of the subject matter to be displayed, except in the infrequent case that .the material consists of symbols having four-fold symmetry 10 .- such as circles., plus signs, crosses of equal arm length and the 1, 4 and 5 spots on dice and the like.
As already noted, the display is shifted to a new posi-tion by the rotation of any.of the driving or slave rollers by one-quarter turn, that is, by 90., for the relative propor-: 15 tions of the particular apparatus depicted in the drawings. Of co~rse, it is a simple matter to change the ratio of the dia-meter of the driving and slave rollers to the spacing distance between a single display ro].ier pair so as to vary the amount of rotation required to produce a new setting in the display.
: 20 We find the ratlos shown and described to be best, however, for it leads to a comfortable amount of working space behind .the display rollers. On FIGURE 6, four index marks 45, 46, 47 ~: and 48 are shown on the face of gear 27, and it will be clear - fxom the foregolng that the display can.be changed by rotatiny .
~ 25 the-driving/slave gear assembly by ~0. This may readily be ; . done by hand with.the aid of either knob.50 on the face of . .
gear 27 or knob 51 on the face of gear.35. ~xact positioning . : is facilitated by observing the four index markings on the ` . . face of gear .~7.. -Remote control of rotation may of course be . 30 effected b~ any~of the means well known to those skilled in .~ ~ . the art, such as by the use of cables, pulleys and the like.
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SUCII reposi-tionincJ of the display ~y hand is adequate in ~any cases ~Ihere the destination is ch~nged infrequently or where only two or three display devices are used, as in ~IGURE 1.
In many other cases, however, it is desirable to be able to reposition the display device automatically. In a destination sign for buses where a large nun~er of characters are displayed, ~n automatic system is d~sirable. A destination sign, as shown in FIGURE 8, comprises an enclosure or case 60 which is provided with a plurality of windows 62 whish display respective - 10 alphanumeric characters making up a destination name. A sign module 64 is positioned within the case 60 behind each window 62 so as to present its character dlsplay through the window.
~ A closed~loop positioning system may be employed for automatic selection of the desired character display. In the device of FIGU~E~ 2 and 4, the uppermost tape 23 bears a coded endstrip ~6 in the por~ion shielded from view. This strip bears positioning markers in an array of parallel channels, the mark-ings consisting of opaque portions in an otherwise transparent o~ translucent tape. The momentary position of tape 23 is registered by an opti~cal code sensor 38 which may conveniently comprise a li~ht source 37 and a multiple photodiode or like receptor means, none of which requires to be set forth in any detail since this general type of coded positioning sensing and registration is well known in the art. The signal given by ~- 25 sensor 38 is used to actuate a drive motor 39 (see FIGURE 6), which again is a matter of weLl-known technology. It is of - course unnecessary to provide more than one of the display tapes with the coded edge portion-since all of the tapes are in effect geared together and move simultaneously as already described.
. .. ,,, As is conventional in closed-loop positioning systems, a command signal is applied to the input according to the posltioning ', ~LCl 7~Z~4 desired, i.e. according to the character to be displayed, The com~ancl signal causes the drive motor 39 to be energized. The - tapes are displaced in unison and the sensor 38 continuously produces a follow-up signal corresponding to the actual posi-tioning of the tapes. The follow-up signal is compared with the comnland signal and when correspondence or equality is achieved, the motor is stoppecl and the selected character is displayed by the tapes. In a closed-loop system, precise posi-tioning of the tapes may be achieved since the positioning code .. . .
is applied to the tape itself and may be positionally correlated with the respec-tive character segments distributed along the length of the tape. While positioning of the tapes by use of a closed-loop positioning system does circumvent certain posi-.
tioning problems, it is disadvantageous in certain respects~
~n particular, where two or more modules are to be used together and adapted to display different characters, it isnecessary to use a separate positioning system for each display device. Further, in a closed-loop system a failure in locating the correct positional code signal will result in the display ~; 20 of a wrong or garbled character, or perhaps, damage to the device. As will be discussed below, an open-loop type of posi-tioning system is preferred and the display device of this invention is adapted for such positioning.
For changing the display from one character to another, an open-loop control system is preferred. For this .. : .
~~ ~ purpose, it is desirable that succeedin~ characters may be - .
selected by advancing or reversing the tapes through equal increments of angular displacement of the driving rollers. -This will enable two or more display modules to be operated ~rom a single drive motor with-individual clutches for each module. However, because the tape lS wrapped in varying ~ ~ - -13-: .' . . .
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amounts on the ro~lers according to the tape positioning, the effective roller diameter varies and a given angular displace-ment o~ a roller does not correspond to the same lineal displace-ment of the tape~ In the illustrative example, the relati~e dimensions have been chosen so that the e~fec-tive diameter of the driving roller is such that one-fourth of a revolution forward - from its home or reference position will take up a length of the tape equal to the axial length of each window segment.
(In-this home positlon, the ef~ective diameter includes the 10 roller diameter plus any tape leader wound thereon.) Accordingly,.
.~the first.revolution of the roller will take up the first four character segments. However, during the next revolution the .
roller will have an effective diameter which is larger by twice the thickness of the tape and will take up a length of .
tape greater than the next four character segments. The effec-tive diameter of the roller continues to increase with approx~-- mately each succeedin~.~roup of four character segments. Thus, it can be seen that as the tape is advanced or taken up further on the driving roller, each ninety degree increment of roller rotation will take up slightly more tape than the previous _increment. So that equal angular increments of roller dis-placement will provide accurate positioning o~ successive . . character segments, the character sé~ments are nonuni~ormly spaced along the length of tape, as will be described subse-.quently.
.- An open-loop positioning system which is especially adapted for a destination sign is illustrated in FIGU~E 9.
Each of the sign modules ~4 in this system is the same as that shown in FIGURE 2 e~cepk that the coding strip 36 and sensor 3G 38 are omitted.~ Por the open-loop positioning system, a shaft , , ,: ' - ~ .
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position encoder 40, as shown in FIGUI~E 6, is qeared to the , ; . drive s~aft for the display devi.ces. As no-ted in FIGURE 6, the drive mo-tor 39 drives each display device through a drive gear 41 and also drives an encoder 40 through a pinion gear on the . 5 same shaft. The shaft position encoder 40 bears an annular . coding strip 42. The coding strip coacts with a light source - ~3 and an optical sensor 44, as depicted in FIGURE 7, to produce . an electrical si~nal corresponding to the angular position of , the driving shaft.
,. 10 , The open-loop positioning system is shown in block ,' diagram in FIGU~E 9. The motor 39 is a reversible electric motor and is provided with an elongated drive shaft 66 ! mechanically coupled w'ith the encoder 40. Each o~ the display modules 64 is separately coupled with the drive sha~t 66 through a respective clutch 68. -A selector means 72 lS adapted to ~,~ produce an electrical signal corresponding to the desired posi-'~ tioning for each of the modules 64. The selector means 72 receives an input signal from the encoder 40 which is indica-tive .
~,~ . of the actual positioning of the motor shaft 66. The encoder , 20 40 also provides a positlon signal to a motor control means 74 - which controls the energization of the motor 39. The output of , the se'Lector means 72 is connected with the input of a clutch '~ control means 76 which supplies individual control signals to . the respecti~e clutches 68. In operation, the'selector means 72 is set according to the desired position for each of the display ; '' modules. Th:is setting inltiates the energization of the motor .
:; 39 'through.the motor control means 74 which causes the motor to , . . .
:' ' drive all of the display devices in the reverse direction to a ': , ' home position. The motor is àu~omatically reversed by the ~ 30 motor contro:L means upon reaching the home position and the 1CD~3Z~3~
P-305/G ' ' '' clutches are se]ectively engaged and disengaged through the clutch control means 76 so that each display module is positioned according to the setting of the selector means. Thus the display modules 64 are controlled independently and are driven concur-rently from the home position to the respec-tiv~ display positions.
So that equal angular increments of roller displace-ment will provide accurate positioning of succe'ssive character segmen'ts, the character segments are nonuniformly spaced along the lenyth of the tape. 'This is depicted in FIGURE 10 which is ' 10 a diagrammatic reprqsentation of tape 23 showing the front sur-face and back surface thereof side-by-side with the respective - diisplay window segments therebetween for showing the positional correlation. The front surface of the tape 23 is shown in fragmentary sections on the left side of FIGURE 10-and these sections are enlarged relative to the showing of the front s'~rface in FIGURE 3a. Similarly, the bac~ surface of the tape ' - 23 is shown'in enlarged, fragmentary sections on the right side of FIGURE 10. l'he back surface view in FIGURE 10 shows th'e tape as it would appear if it were turned side~for-side from the front surface view, i.e. the tape is turned over by rotation - about its longitudinal axis. ~In FIGURES 3a and 3b, the tape `~ ' in FIGURE 3b is turned end-for-end from the position shown in -FIGURE 3a, i.e. it is turned over by rotation about a transverse .: :
axis.) The tape 23 comprises a leader 162 at one end thereof which ~is secured to the driving roller 15. It also comprises a leader 164 at the other end thereof which is secured to the slave roller 19~ -The tape 23, between the leaders, comprises a ;; plurallty of tspe surface se~ments 166,~ each of which is of , ' rectangulàr shape and extends the full width of the tape. The surface segments 166 in a group, A, are of the same length; the . j.. ~-; ~- ~ ; .
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surface segments 166 in successive groups B,C, etc. are progressively longer. I'hc shortest surface seg~ents are adjacent the leader 162 and the longes-t are adjacent the leader 164. The surface segments 166 accommodate the various character segments, such as character segment 33 which is shown in actual configura-tion in FIGURE 10 and in FIGU~E 3a. The other character segments are represented in FIGURE lO in dummy form by the hatched I sections, one of which is superposed upon each of the tape sur-.
face segments 166. It is noted that each'of the character segments is allotted an axial length, C. This leng-th, C, is suitably equal to the axial dimension of the shortest of the tape segments'166. The tape segments in each succeeding group are longer than those in the preceding group by an incremental length, so that an extension 168 is provided for the character s$gments, as indicated. This extension will vary from zero length for the character segments in the first group (group A) to a maximum'length for the character segments in the last group. In practice, the extensions 168 are not left blank; instead, the character configuration is extended through that portion so as to avoid showing a-~lank line in a character display in case o a positioning error. ' '' FIGURE 10 also depicts the positionaL relationship' of the front and back surfaces of the tape 2'3 in relation to a - .
viewing window 170. The viewing window is an aperture or area'-bounded by the sides of the character segments and the top and' ' bottom, respectively, of the uppermost and lowermost character ' segments.' In the device as depic-ted in FIGURE 2, the window - 170 is defined by the opening in the front of the frame of the .
device~ It :is noted that in FIGURE 10 the tape 23 is depicted as being laid flat alongside the window 170, whereas, in fact, .. ~ . . . .
: . the tape 23 is disposed within'the window and is looped over the ~' ' ~ ' ~ ' ' ' .
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, display rollers and partially wound on the driving and slave rollers. The window 170 is divided into plural window segments 172a,172b and so forth, according to the total number of character segments to be displayed at a time. Each window segment has an axial length, L, equal to the axial length, C, of the character segments. It will be unde~rstood that the window segments are not separated by physical boundaries, instead, each window segment is an allotment of space from the total window area to a' character segment which has the same relative position in the character format as the window segment has in the window area.
In FIGURE 10, the tape 23 is shown' in the same position relative to the display window 170 as it is in FIGURE 2, i.e.
the letter A is displayed and the character segment 33 is dis-played in the window segment 172a. The back side of the tape 15-~ 23, as'shown in FIGURE 8, is comprised of tape surface segments 166' which are progressively longer, by groups, as described above with reference to the front surface. The characte'r~seg-ments are all of the same length and the extensions 168' vary ~ ~ in the same manner as described above. With the'tape 23 in the ;~ - 20 position for displaying the character A, as described, the , , . . .
' character segment 3'4 is displayed in the window segment 172b.
The remalning segments of the character A will appear in the ' respective window segments as depicted in FIGURE 2.
' In the illustrative embodiment, it is to be noted . ~ , .
that ninety degree increments of rotation of the driving rollers ' will successively present the successive character segments -~: :
in accurate alignment with the respective window segments.
It will be understood that the relative dimenslons oE the roller diameter ancl the character segments may be changed to suit a ' ~ 30 particular clesign. - ' 18- ' .' ..
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The tape material is preferably a thin sheet stock which has hi~h tensile st~ength and which is dimensionally stable under varying ambient temperature and humidity conditions. One preferred materi~l is polyester film such as -that sold under the trademark "Mylar" by E.I. du Pont de Nemours of Wilmington, Delaware. Even with a thin tape, the wrap-up of the tape on the roller has a significant effect upon the accurate positioning of the character segments. It has been found that this problem of tape wrap-up is exaggerated by the use of small rollers.
The small roller requlres a large increment of roller rotation, as compared to a large roller, for producing a gi~en character - segment length. It can be shown that the-length of successive tape segments for equal increments of roller rotation varies as the square of the angular increment. Accordingly, a large angular increment which is required for small rollers will result in a large variation in tape segment length and hence there will ~e inefficient use of the tape due to the unused space between character segments, i.e. the extensions 168 shown in FIGURE 10 and described above. To minimize this effect, it is desirable to use large rollers. Further, the tape thickness will differ somewhat from the design value and this will con- -tribute to positioning error. The positioning error due to tape thickness variation will vary with the square of the incremental angle of roller rotation for each character segment and with the square of the number of character segments. ~herefore this :
error is minimized by the use of a larger roller. It is prefer-red that the roller diameter be made approximately equal to the sum of the distance spanned by two window segments, i.e. ~
approximately~equal to twice the distance between the polnts of tangency ll and 12 ln FIGURE 2. This provides a tape segment '- ~ ~ . - . ' ' . .
~: ~ .. . . .
~0732~39L ;
angle of about ninety degrees or about four tape segments per circ~lmference.
Although an open-loop positioning system is advanta- :
geous in many respects, it does not provide absolu-te accuracy in positioning the tapes for the character displays. Accordingly, the foregoing features of character segment spacing and roller diameter are of great importance in producing charac~ers with faithful reproduction, especially where a large number of characters, for example forty or so, are represented in a single module. Additionally, the fidelity of character reproduc-tion is enhanced by proper selection of the number of segmentsper character. The number of segments per character shouId be - selected so that each horizontal bar in a character is provided by one, and only one, character segment; fur-therl such character segment should carry no portion of the character other than the - horizontal bar. With this arrangement, the upper and lower : edges of the horizontal bar necessarily occur at the crac~s between segments. It has been found that this requirement is fulfilled best with eight segments per character because it ~ permits proper relative positioning of the horizontal bars in all characters in all classes or fonts of character styles. It is - found that six segments per character does not permit proper placement of the horizontal bars without fragmenting a bar, with parts on two segments; ten segments per character is too many and horizontal bars would have to be fragmented to obtain proper placement.
In order to compensate for positioning errors of the character segments in displaying a given character, the appear ance of misalignment is minimized by fa.iring of the character ` ~ 30 segments at the upper and lower extremities thereof. This is ~`' ' ' : ' ' , ~` ,' ' ;.. ,' ' .
' '.' " "' ', ' '' ' ~,"'"'' ' ' .' .''''" ' ,', ' '";' ' ', ..'" :,. '' ' :' " '' 1C~732~
illustra-ted in FIGURE 10 which shows the character segments 33 and 34. In -these segments, for example, the charac-ter lines at the upper extremities 176 and at the lower extremi-tles 178 are faired toward the vertical direction, i.e the lines are diverted from the trend line of the character style to approach asymptotically a vertical line. Consequently, when two adjacent character segments are not accurately positioned the appearance of misalignment of the character trend line is minimized.
As described above, the driving rollers 15, 16, 17 and 18 are directly driven by the roller shafts and the slave rollers 19, 20, 21 and 22 are spring dri~en by the roller shafts to compensate for the disparity in the required angular - rotation for linear payout and uptake in transferring tape from one roller to the other. The driving rollers are positioned i~nediately behind the window segments and the driven rollers are immediately behind the driving rollers. Each pair of driving and slave rollers, being of a diameter approximately equal to two window segments, is accommodated in the space of the projected area of the respec~ive windo~ segments. This ~- ~ - . . .
- 20 enables-the module to be of compact design within a rectangular box havlng a height and width substantially equal to that of the window.
Reverting a~ain to the winding arxangement of the tapes, it is observed that the tape is always held ln tension by reason of the spring loading in the slave roller. It is dèsirable to maintain the tape tension at a value such that it will be stretched ~ightly across the display rollers but, o~ course, the spring loading varies with the amount of tape : ~
windup on the driving rollerO The spring loading is the smallest when most of the tape is on the slave roller and in this - . ~ .
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condition the spring torque, working aginst -the friction in . ` the tape and roller system, may tend to allow the tape to become somewhat slack across the display rollers. This is overcome in the winding arrangement, as shown in FIGURE 4, by laying the loop of tape from the display rollers directly upon the driving roller. Note that for each set of rollers, the tape passes immediately from the driving ro:Ller over a first set of display rollers and thence is looped back over the driving roller in .
engagement therewith over more than 180 before it is passed over the second setlof display rollers to the slave roller.
This causes the driving roller to serve as.a feed roller and . obviates the need for idler rollers for looping the tape. As a feed roller it tends to keep the tape tigllt over the display rollers for both directions of rotation of the driving roller.
A modification of the invention is shown in FIGURES 11 ~ .... . . .
and 12. In this embodiment of the invention, the tapes are wound upon and displayed from the surfaces of the driving and slave rollers; the display rollers used in the embodiment of FIGURE 2 are dispensed with. Referring to FIGURES 11 and 12, the display module ~0 comprises a frame 82 and plural sets of-- driving and slave rollers. Each driving roller 8~, 85, 86 and : 87 is d.irectly connected with its respective shaft and carries : a gear 88, 89, 90 and 91 which lS fixedly connected therewith.
Each of the slave rollers 92~-93,~94 and 95 is spring loaded in the same manner as slave roller 19 described with reference.
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to FIG~RE 5. Each of the slave rollers is connected through a ` . spring loaded-shaft with respective gears 96, 97, 98 and 99u An input gear 101 is manuallly operable by a crank lQ2 and is meshed directly with gear 97 of the~slave roller 93. All of the driving and:slave rollers are of the same diameter and all of . .
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the gea~s, except the input gear 101, are of the sa~e size, It is noted that the rollers are of a diameter approximately equal to a single window segment of the display where a window.segment is that portion of the total display area which is allotted to a single character segment. A tape 103 has one end secured to the driving roller 84 and the other end secured to the slave roller 92, the tape being wound between the rollers in an "S" configura-tion. Similarly, a tape 10~ is connected between the driving roller 85 and the slave roller 93, the tape 105 is connected between the drivinglroller 86 and the slave roller 94 and the tape 106 is connected between the driving roller 87 and the slave roller 95. The various characters represented by the module are displayed successively by rotation of the input gear through successive an~ular increments of equal value.
Although the description of this invention has been ~iven with reference to a particular embodimellt, it is not to be construed in a limiting sense, many variations and modifications will now occur to those skilled in the art. For a definition of the invention reference is made to the appended claims~
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This application is a divis:ional of Canadian Patent Application Serial No. 245,005, filed February 4, 1976 by Associated Data Concepts.
This invention relates to information displays and particularly to such displays as are capable of presentlng any of a number of alphanumeric displays.
The problem of presenting a readily changeable alphanumeric readout in a small space has been solved in many different fashions, as exempliied by neon-glow-discharge tubes, liquid crystal readouts, solid-state electro-luminescent devices, and the like. Most such arrangements require operating signals which themselves contain most or all of the information to be displayed, and in any case are in general poorly adapted to large scale readouts, such as may be seen readily from a considerable distance. Further, a general problem with light-emitting displays is illegibility when the ambient light level is high. Cpaque displays, in contrast, increase in visi-bility as the ambient light increases.
A need exists for a mechanically sound, readily and quickly change-able and accurate display for such diversified uses as des~ination indicators for buses, advertising signs, indicators of ambient temperature, time o day, and the like.
~0 An object o the present invention is to provide a readily change- -able display device adapted to displaying letters, numerals, words and phrases and the like within the framework of a mechanically sound apparatus.
Another object o the invention is to provide such a device inclu-ding posi~ioning means whereby the display may be selectively changed to any desired configuration~ and is especially well adapted to positioning by automatic devices, particularlythose under computer or mach~ne control.
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~ particular application of the subject invention is in the field of destination signs for transit vehicles such as buses and trains. Such destination signs mus-t be changeable according to the particular route of the vehicle and, in modern day transit systems, each sign must be capable of displaying a - large number of different destination names in alphanumeric form. A typical destination name may require forty or more characters and the sign must be changeable quickly from one name to another. In the past, destination signs have taken the form of a rQller curtain wide enough to accommodate the requisite number of characters and long enough to hold a full set of destinatlon names requlred for a given vehicle. One great dif-ficulty with this type of destination sign is that the roller curtains must be printed with special destination names according - 15 to the route of a particular vehicle or fleet of vehicles. This requires the printing of a large number of different destination signs for a given metropolitan area ~ith attendant high cost.
Furthermore, with long sign curtains, it is difficult and - expensive to provide automatic sign changing systems.
The rollerlcurtain destination sign, despite the ~ .
~ ~ above-mentioned difficulties, has an exceedingly important , attribute, namely, it affords excellent readability despite - . . . .
wlde variatlons in ambient light. Further, it lends itself to ~ large scale dlsplays so the sign can be read from a distance.
; 2~ As alluded to above, the roller curtain destination sign in the :' :
form of an opaque display, is presently preferred for des~ina-tion signs over all other known displays.
-` This invention~seeks to ta~e advantage of the read~
ability of an opaque display and to overcome the difficulties of . 30 the roller curtain destination sign. In general, this is , accomplished by a sign having a plurality of window areas ;
~ - -2-1~73Z~ ;
each of which is adapted to display one alphanumeric character at a time on a set of display tapes; each window area is capable of - selectively displaying any one set of characters by selectively positioning the respective tapes of the set. Thus, a selected S destination name may be displayed by selec-tive positioning of the sets of tapes.
This scheme allows any destination name to be formed and displayed using identical sets of character display tapes - for each character window area. Thus, the same set of character display tapes may be produced in multiple copies to make up a' de,stinatlon sign and the same,destination sign may be used on any route since any destination-name may be formed by the sign.
To make practical this concept of a universal des-tina- , , tion sign, this invention provides a broken-character, broken-word arrangement. The broken-character utilizes plural display tapes to form each character rather than a single tape showing ' all characters in succes'sion; by thls'technique; each tape is ~ ' shortened to a fraction o the length of the single tape.
'~, ' Therefor the wrap-up of the tapes is minimized and the maximum displacement of any tape to form any character is a fraction of , that required in the case of a ,single tape. The broken-word -- -arrangement utilizes the,tapes in each set which are only one - character wide and which are used for only one window area.
~ ' ,The tapes of each set are positionable independently of the ,~ 25 tapes of any other set; this enables the number of character ' ~. . . . . .
~ ' portions disposed along the length'of each tape to be kept at an -, -' absolute minimum (since,the tape is only one character wide and , no pairs or combinations of character portions are involved laterally~. ,This arrangement allows the sets of tapes to be : , - , - . ' displaced simultaneously to form their respective characters.
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According to this lnvention, a changeable display of printed alphanumeric characters is provided which faithfully reproduces each character, one at a time with a minimum of translatory motion required in changing from one character to another. In general, this is accomplished by using a set of display tapes with each tape bearing discrete character segment which are imprinted on both front and back surfaces of the tape. A driving roller is connected with one end of each tape and a driven roller is con-nected with the other end, and the tape is supported for displaying one sur-face segment of the front and the back of each tape in respective segments of each window. The set of surface segments being displayed together in the window all bear different character segments of the same character so that an entire character is displayed. Means are provided for displacing the tapes in unison along their length to successively present the character segments in registry with the respective window segments whereby all ~, characters of the set may be successively displayed. The number of display tapes in the set is equal to one-half the number of character segments.
The surface segments on both surfacec of each tape become progressively longer frol: one end of the tape to the other.
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Further, in accordance with the invention~ faithful reproduction of the characters is provided by means which ensures proper positioning of the character segments within the respective window segments. This is accomplished by placing the character segments on respective surface segments of the tape with the surface segments being progressively longer from one end of the tape to the other to allow for wrap-up of the -tape on the rollers.
Further, the character segments are nonuniformly spaced along the length of the tape so that equal angular displacements of the driving roller causes proper alignment of the character segments in the window segments.
Further, accordinglto the invention, the proper positioning of the character segments is enhanced by relating the roller size to the length of character segments. In particular, the diameter of the rollers should be approximately equal to the length of two character segments.
Further, according to the inve~tion, the display of each character, even though it is a composite of several segments, is produced without dis-tortion. For this purpose the number of character segments is selected so that the horizontal bars of a character may be carried all on one segment and yet be properly located in the character format. Preferably, the number of character segments is eight. Additionally~ distortion between ~0 adjacent segments is minimized by fairing of the character line at the upper and lower extremitles of the segments.
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Further, according to the invention, the driving and driven rollers are disposed in a minimum of space and may be driven by a single input shaft so the rollers move only in unison. This is accomplished by placing the driving roller oE each set behind the display window and the driven roller immediately behind the driving roller with equal size gears on all rollers and meshing with at least one adjacent gear.
A more complete understanding of this invention, as well as that disclosed in application Serial No. 245,005, may be obtained from the follow-ing description, taken with the accompanying drawings in which:
FIGURE 1 is a front view of three display units in accordance with the invention, each exhibiting a different numeral or figure;
FIGURE 2 is a partially cut-away perspective view of a typical embodiment of the inventive display unit;
FIGURES 3a and 3b are respectively the front and back sides of a display tape such as may be used in the device;
FIGURE 4 is a diagrammatic side view of the device showing the winding mode of the display tape on the rollers;
FIGURE 5 is a sectional view showing the detailed construction of :
a slave roller;
FIGURE 6 is a diagrammatic side view showing the inter-meshing coupling means whereby the driving rollers are rotated and showing an ; optional positioning code disc;
FIGURE 7 is a top fragmentary view of the code disc shown in FIGUF~ 6 "
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FIGURE 8 shows'a des-tination sign accordiny to this invention;
FIGUR~ 9 shows a posltioning control system for use in this invention;
FIGURE 10 is a diagrammatic showing of the relative positioning of the character segments on.the tape;
. .FIGURE 11 shows a modification of the invention; and ': FIGURE 12 is a sectional view taken on lines 11~11 '. . of FIGURE 11. 1 ' 10Coming now to FIGURES 2 and 4~ it will be seen that the device comprises an array of display rollers, 1, 2, 3, 4, 5, 6, '.
7, 8, 9, 10, etc., which are arranged in spaced pairs,'1,2; 3,4;
etc., and in which two'adjacent pairs form.groups of four rollers each, such as 1-4 inclusive, 5-8 inclusive, and so forth. Further~
~ 15 m~re, all of the axes of the cylindrical display rollers 1, 2,' 3, ~ ' etc., are in-the same plane so that all of the cylindrlcal'dis -- play rollers are tangent to a display plane, the position of this ;. ' tangent'display.plane-being indicated.in the drawings by those .~ . segments of .the tapes which lie flat on the front of the display , device, as sho~, for example,'in FIGURE'2 by that portion of the ': : .uppermost tape lying between the points indicated as 11,12,13 and ~4.
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.. - It will be apparent from the drawi~gs and in particular from.FIGURES 1 and'2 that those portions of the display tapés ~ ~isible from the outside form an'array of essentiall'y horizon~
1 ~: - . : , 25~ tal segments ~hich may be viewed as a whole,.thus for example' in ~IGURE 2 displaying the letter "A" made up of eight horizontal gment . ' Reverting now to FIGURE 4, this illustrates the fashion~
.' in which the tapes are;wound:on and over their respectlve rollers.
.Each group of four display rollers, 1-4,5-8,9-12, etc., is backed up by a drivinq roller 15,~16~, 17 and 18, and by a slave roller ,: , ~ , . : :. . , ~ . .
32~4 19, 20, 21 and 22. A tape 23 is ~sten~d at one end to the driving roller 15, and after looping over the back of the driving roller is threaded over display rollers 2 and 1 and thence back over driving roller 15 and thence is threaded over display rol-lers 3 and 4 and is finally taken up by slave roller 19, to which ` its opposite end is fastened.
- It will be observed that in passing over display rol-. .lers.l and 2, one face of the tape 23 is exposed to view, where-as when the tape passes over display rollers 3 and 4 the back or reverse side of the same tape is displayed.
- It will be further noted that the next unit in the . stack comprising display roller 5, 6, 7 and 8, driving roller 16 and slave roller 20, has its own tape 24. The same is true for t~e remaining units ln this stack involving drlving rollers 15. ~7 and 18, slave rollers 21 and.22, and tapes 25 and 26 respec-tively. Further, proceeding from the top of the stack downward each succ~ssive driving roller toyether with all the rollers actuated thereby rotates in a sense opposite to that of its . - neighbor next below, for reasons which will appear later.
. 20 . . In the em~odiment shown in the drawings, four units are - shown in a vertical stack. It will be clear that more or fewer . . . .
~ couldibe used in accordance with the nature of the information .~: : - .
~ to be dispIayed. Likewise, FIGURE 1 shows three such four : .
stack arrays in horizontal juxtaposition. This enables the information on each of the three devices to be varied indepen-dently of the others, which in some instances is advantageous,-as for example when various numbers or various words are to be . shown. Clearly, if for example 20 devices are assembled in a horizontal array.and i each device can display each of the 26 letters of the alphabet and the ten digits rom 0 to 9, then . ; . ;any word of up to 20 letters or any digit up to 1 X 102 - 1 .~
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1073'~
can be displayed at will.
~everting cnce more to the clrawings, the slave rollers 19, 20, 21 and 22 are take-up rollers which serve to wind up, or as the case may be, to unwind the tape when the display is changed. All of the driving rollers 15, 16, 17 and 18 and the slave rollers 19, 20, 21 and 22 are geared together as may be seen from FIGURE 6, and because of the relative sense of rotation of the various rollers this may be done in the extra-ordinarily simple fashion shown in FIGURE 6. Thus, all of the ' . 10 gears are meshed together at their points of contact, which 'i ' leads.to a complete avoidance of any slippage problems which . might otherwise cause'the tapes in a given stack to become .out of phase. As a given tape is wound from its driving roller onto its slave roll'er, or contrariwise, it will be clear that a . 15. given.amount of angular rotation will correspond to a.slightly .i~ . i ."
~ - varying linear payout or uptake because of the finite thickness : . of the wound tape. We compensate for this slight disparity in . the required angular rotation between a given driving roller and ~ .its slave roller by providing a spring loading in torque for ~ 20 each slave roller, as may be seen from FIGURE 5. It will be , .~ - , . . .
.~ ' . clear from .that drawing that the gear 27 does ~ot drive the '~ roller 19 directly and positively but only through the inter-mediary of a helical spring 28, which is set so as to impart a . moderate degree of tension in the tape. Spring 28 is engaged at one end to endpiece 29 forming part of the slave rol~er 19;.
whereias at the other end it engages anchor pin 30 which.is .
'`'~ . fixedly attached to the-drive shaft 31 which in turn is fixedly .
attached to gear wheel ~27. A stop pin 32 is attached to end-: piece 49 of slave roller'l9, and serves to limit the rotation : 30 of shaft 31 with respect to slave roller 19. It serves to hold the spring 28 from being overstressed during operation if ' .. , . .................... ~ .:
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~73~04 the tape or roller should stick. The arrange~nent of course is repeated ~or each unit in the stack.
It will be clear from the foregoing and particularly, from FIGURE 2, that the array of gears attached to the driving rollers are not only intermeshed with each other, but are also intermeshed with the array of gears which are attached to the slave rollers, and both arrays are intermeshed so that all o the gears may only rotate in unison,'taking into account the opposite senses of rotation of adjacent gears. Thus each driving roller gear engagés at least one other driving roller gear as well as its corresponding slave roller gear; and the same may be said for each of the slave roller gears, each one of these engaging at least one other slave roller gear while at the same time engaging its corresponding driving gear.
., Turning for the moment to FIGURES 3a and 3b, these show respectively the front and back sides of tape 23, which as .
will be appreciated from the foregoing explanation has, ~ , depending upon ,the particular setting of the device, a segment of one side displayed between display rollers 1 and 2, and another segment fro~ the other side displayed between the '~
display rollérs 3 and 4. FIGURE 1 shows the setting of the de-vice so as to display the letter "A". In FIGURE 3a, that segment forming the top half of the upper one-quar,ter of the let-.
' ter,"A" is indicated by 33; whereas that portion of the reverse ' of the tape shown on FIGURE 3 b which forms the lower half of ~ . .
', the uppermost one-qu'arter of th,e letter i'A" is indicated by 34.
, The tape shown in FIGURES 3a and 3b bears sufficient markings ~, to form the upper'one-quarter'portion~ that is, between rollers 1 and 4, ,of all 26 letters of the alphabet, all ten digits from .
, ~ 30 0 through 9, a period,(.?,'a dash (-), a slash ~), and a blank space., ` ~ ~ ' -10--, ~ : .
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~732(~ -t It may be remarked that ~or con~enience in explaining . our invention we-have shown the various rollers as horizontal, I with the stacking vertical; but the terms "horizontal" and i "yertical" are used mainly for convenience. It is self-evident that the entire apparatus shown may be rotated through 90, so that the rollers will then be vertically disposed. Obvio~s changes will then have to be made in.the arrangement of the subject matter to be displayed, except in the infrequent case that .the material consists of symbols having four-fold symmetry 10 .- such as circles., plus signs, crosses of equal arm length and the 1, 4 and 5 spots on dice and the like.
As already noted, the display is shifted to a new posi-tion by the rotation of any.of the driving or slave rollers by one-quarter turn, that is, by 90., for the relative propor-: 15 tions of the particular apparatus depicted in the drawings. Of co~rse, it is a simple matter to change the ratio of the dia-meter of the driving and slave rollers to the spacing distance between a single display ro].ier pair so as to vary the amount of rotation required to produce a new setting in the display.
: 20 We find the ratlos shown and described to be best, however, for it leads to a comfortable amount of working space behind .the display rollers. On FIGURE 6, four index marks 45, 46, 47 ~: and 48 are shown on the face of gear 27, and it will be clear - fxom the foregolng that the display can.be changed by rotatiny .
~ 25 the-driving/slave gear assembly by ~0. This may readily be ; . done by hand with.the aid of either knob.50 on the face of . .
gear 27 or knob 51 on the face of gear.35. ~xact positioning . : is facilitated by observing the four index markings on the ` . . face of gear .~7.. -Remote control of rotation may of course be . 30 effected b~ any~of the means well known to those skilled in .~ ~ . the art, such as by the use of cables, pulleys and the like.
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SUCII reposi-tionincJ of the display ~y hand is adequate in ~any cases ~Ihere the destination is ch~nged infrequently or where only two or three display devices are used, as in ~IGURE 1.
In many other cases, however, it is desirable to be able to reposition the display device automatically. In a destination sign for buses where a large nun~er of characters are displayed, ~n automatic system is d~sirable. A destination sign, as shown in FIGURE 8, comprises an enclosure or case 60 which is provided with a plurality of windows 62 whish display respective - 10 alphanumeric characters making up a destination name. A sign module 64 is positioned within the case 60 behind each window 62 so as to present its character dlsplay through the window.
~ A closed~loop positioning system may be employed for automatic selection of the desired character display. In the device of FIGU~E~ 2 and 4, the uppermost tape 23 bears a coded endstrip ~6 in the por~ion shielded from view. This strip bears positioning markers in an array of parallel channels, the mark-ings consisting of opaque portions in an otherwise transparent o~ translucent tape. The momentary position of tape 23 is registered by an opti~cal code sensor 38 which may conveniently comprise a li~ht source 37 and a multiple photodiode or like receptor means, none of which requires to be set forth in any detail since this general type of coded positioning sensing and registration is well known in the art. The signal given by ~- 25 sensor 38 is used to actuate a drive motor 39 (see FIGURE 6), which again is a matter of weLl-known technology. It is of - course unnecessary to provide more than one of the display tapes with the coded edge portion-since all of the tapes are in effect geared together and move simultaneously as already described.
. .. ,,, As is conventional in closed-loop positioning systems, a command signal is applied to the input according to the posltioning ', ~LCl 7~Z~4 desired, i.e. according to the character to be displayed, The com~ancl signal causes the drive motor 39 to be energized. The - tapes are displaced in unison and the sensor 38 continuously produces a follow-up signal corresponding to the actual posi-tioning of the tapes. The follow-up signal is compared with the comnland signal and when correspondence or equality is achieved, the motor is stoppecl and the selected character is displayed by the tapes. In a closed-loop system, precise posi-tioning of the tapes may be achieved since the positioning code .. . .
is applied to the tape itself and may be positionally correlated with the respec-tive character segments distributed along the length of the tape. While positioning of the tapes by use of a closed-loop positioning system does circumvent certain posi-.
tioning problems, it is disadvantageous in certain respects~
~n particular, where two or more modules are to be used together and adapted to display different characters, it isnecessary to use a separate positioning system for each display device. Further, in a closed-loop system a failure in locating the correct positional code signal will result in the display ~; 20 of a wrong or garbled character, or perhaps, damage to the device. As will be discussed below, an open-loop type of posi-tioning system is preferred and the display device of this invention is adapted for such positioning.
For changing the display from one character to another, an open-loop control system is preferred. For this .. : .
~~ ~ purpose, it is desirable that succeedin~ characters may be - .
selected by advancing or reversing the tapes through equal increments of angular displacement of the driving rollers. -This will enable two or more display modules to be operated ~rom a single drive motor with-individual clutches for each module. However, because the tape lS wrapped in varying ~ ~ - -13-: .' . . .
: ~ :
.
~ 732~
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amounts on the ro~lers according to the tape positioning, the effective roller diameter varies and a given angular displace-ment o~ a roller does not correspond to the same lineal displace-ment of the tape~ In the illustrative example, the relati~e dimensions have been chosen so that the e~fec-tive diameter of the driving roller is such that one-fourth of a revolution forward - from its home or reference position will take up a length of the tape equal to the axial length of each window segment.
(In-this home positlon, the ef~ective diameter includes the 10 roller diameter plus any tape leader wound thereon.) Accordingly,.
.~the first.revolution of the roller will take up the first four character segments. However, during the next revolution the .
roller will have an effective diameter which is larger by twice the thickness of the tape and will take up a length of .
tape greater than the next four character segments. The effec-tive diameter of the roller continues to increase with approx~-- mately each succeedin~.~roup of four character segments. Thus, it can be seen that as the tape is advanced or taken up further on the driving roller, each ninety degree increment of roller rotation will take up slightly more tape than the previous _increment. So that equal angular increments of roller dis-placement will provide accurate positioning o~ successive . . character segments, the character sé~ments are nonuni~ormly spaced along the length of tape, as will be described subse-.quently.
.- An open-loop positioning system which is especially adapted for a destination sign is illustrated in FIGU~E 9.
Each of the sign modules ~4 in this system is the same as that shown in FIGURE 2 e~cepk that the coding strip 36 and sensor 3G 38 are omitted.~ Por the open-loop positioning system, a shaft , , ,: ' - ~ .
, ' ` ' . : .
' ~' ' ' , 1~73209L
position encoder 40, as shown in FIGUI~E 6, is qeared to the , ; . drive s~aft for the display devi.ces. As no-ted in FIGURE 6, the drive mo-tor 39 drives each display device through a drive gear 41 and also drives an encoder 40 through a pinion gear on the . 5 same shaft. The shaft position encoder 40 bears an annular . coding strip 42. The coding strip coacts with a light source - ~3 and an optical sensor 44, as depicted in FIGURE 7, to produce . an electrical si~nal corresponding to the angular position of , the driving shaft.
,. 10 , The open-loop positioning system is shown in block ,' diagram in FIGU~E 9. The motor 39 is a reversible electric motor and is provided with an elongated drive shaft 66 ! mechanically coupled w'ith the encoder 40. Each o~ the display modules 64 is separately coupled with the drive sha~t 66 through a respective clutch 68. -A selector means 72 lS adapted to ~,~ produce an electrical signal corresponding to the desired posi-'~ tioning for each of the modules 64. The selector means 72 receives an input signal from the encoder 40 which is indica-tive .
~,~ . of the actual positioning of the motor shaft 66. The encoder , 20 40 also provides a positlon signal to a motor control means 74 - which controls the energization of the motor 39. The output of , the se'Lector means 72 is connected with the input of a clutch '~ control means 76 which supplies individual control signals to . the respecti~e clutches 68. In operation, the'selector means 72 is set according to the desired position for each of the display ; '' modules. Th:is setting inltiates the energization of the motor .
:; 39 'through.the motor control means 74 which causes the motor to , . . .
:' ' drive all of the display devices in the reverse direction to a ': , ' home position. The motor is àu~omatically reversed by the ~ 30 motor contro:L means upon reaching the home position and the 1CD~3Z~3~
P-305/G ' ' '' clutches are se]ectively engaged and disengaged through the clutch control means 76 so that each display module is positioned according to the setting of the selector means. Thus the display modules 64 are controlled independently and are driven concur-rently from the home position to the respec-tiv~ display positions.
So that equal angular increments of roller displace-ment will provide accurate positioning of succe'ssive character segmen'ts, the character segments are nonuniformly spaced along the lenyth of the tape. 'This is depicted in FIGURE 10 which is ' 10 a diagrammatic reprqsentation of tape 23 showing the front sur-face and back surface thereof side-by-side with the respective - diisplay window segments therebetween for showing the positional correlation. The front surface of the tape 23 is shown in fragmentary sections on the left side of FIGURE 10-and these sections are enlarged relative to the showing of the front s'~rface in FIGURE 3a. Similarly, the bac~ surface of the tape ' - 23 is shown'in enlarged, fragmentary sections on the right side of FIGURE 10. l'he back surface view in FIGURE 10 shows th'e tape as it would appear if it were turned side~for-side from the front surface view, i.e. the tape is turned over by rotation - about its longitudinal axis. ~In FIGURES 3a and 3b, the tape `~ ' in FIGURE 3b is turned end-for-end from the position shown in -FIGURE 3a, i.e. it is turned over by rotation about a transverse .: :
axis.) The tape 23 comprises a leader 162 at one end thereof which ~is secured to the driving roller 15. It also comprises a leader 164 at the other end thereof which is secured to the slave roller 19~ -The tape 23, between the leaders, comprises a ;; plurallty of tspe surface se~ments 166,~ each of which is of , ' rectangulàr shape and extends the full width of the tape. The surface segments 166 in a group, A, are of the same length; the . j.. ~-; ~- ~ ; .
: . , ~ 16~
., ~ . . , ... , . . .~ ~ " . . . .
:~ . .
~073~
surface segments 166 in successive groups B,C, etc. are progressively longer. I'hc shortest surface seg~ents are adjacent the leader 162 and the longes-t are adjacent the leader 164. The surface segments 166 accommodate the various character segments, such as character segment 33 which is shown in actual configura-tion in FIGURE 10 and in FIGU~E 3a. The other character segments are represented in FIGURE lO in dummy form by the hatched I sections, one of which is superposed upon each of the tape sur-.
face segments 166. It is noted that each'of the character segments is allotted an axial length, C. This leng-th, C, is suitably equal to the axial dimension of the shortest of the tape segments'166. The tape segments in each succeeding group are longer than those in the preceding group by an incremental length, so that an extension 168 is provided for the character s$gments, as indicated. This extension will vary from zero length for the character segments in the first group (group A) to a maximum'length for the character segments in the last group. In practice, the extensions 168 are not left blank; instead, the character configuration is extended through that portion so as to avoid showing a-~lank line in a character display in case o a positioning error. ' '' FIGURE 10 also depicts the positionaL relationship' of the front and back surfaces of the tape 2'3 in relation to a - .
viewing window 170. The viewing window is an aperture or area'-bounded by the sides of the character segments and the top and' ' bottom, respectively, of the uppermost and lowermost character ' segments.' In the device as depic-ted in FIGURE 2, the window - 170 is defined by the opening in the front of the frame of the .
device~ It :is noted that in FIGURE 10 the tape 23 is depicted as being laid flat alongside the window 170, whereas, in fact, .. ~ . . . .
: . the tape 23 is disposed within'the window and is looped over the ~' ' ~ ' ~ ' ' ' .
:- . ,' . , : . . -1~73;2~J~
, display rollers and partially wound on the driving and slave rollers. The window 170 is divided into plural window segments 172a,172b and so forth, according to the total number of character segments to be displayed at a time. Each window segment has an axial length, L, equal to the axial length, C, of the character segments. It will be unde~rstood that the window segments are not separated by physical boundaries, instead, each window segment is an allotment of space from the total window area to a' character segment which has the same relative position in the character format as the window segment has in the window area.
In FIGURE 10, the tape 23 is shown' in the same position relative to the display window 170 as it is in FIGURE 2, i.e.
the letter A is displayed and the character segment 33 is dis-played in the window segment 172a. The back side of the tape 15-~ 23, as'shown in FIGURE 8, is comprised of tape surface segments 166' which are progressively longer, by groups, as described above with reference to the front surface. The characte'r~seg-ments are all of the same length and the extensions 168' vary ~ ~ in the same manner as described above. With the'tape 23 in the ;~ - 20 position for displaying the character A, as described, the , , . . .
' character segment 3'4 is displayed in the window segment 172b.
The remalning segments of the character A will appear in the ' respective window segments as depicted in FIGURE 2.
' In the illustrative embodiment, it is to be noted . ~ , .
that ninety degree increments of rotation of the driving rollers ' will successively present the successive character segments -~: :
in accurate alignment with the respective window segments.
It will be understood that the relative dimenslons oE the roller diameter ancl the character segments may be changed to suit a ' ~ 30 particular clesign. - ' 18- ' .' ..
~7;~0~
P~305/~
The tape material is preferably a thin sheet stock which has hi~h tensile st~ength and which is dimensionally stable under varying ambient temperature and humidity conditions. One preferred materi~l is polyester film such as -that sold under the trademark "Mylar" by E.I. du Pont de Nemours of Wilmington, Delaware. Even with a thin tape, the wrap-up of the tape on the roller has a significant effect upon the accurate positioning of the character segments. It has been found that this problem of tape wrap-up is exaggerated by the use of small rollers.
The small roller requlres a large increment of roller rotation, as compared to a large roller, for producing a gi~en character - segment length. It can be shown that the-length of successive tape segments for equal increments of roller rotation varies as the square of the angular increment. Accordingly, a large angular increment which is required for small rollers will result in a large variation in tape segment length and hence there will ~e inefficient use of the tape due to the unused space between character segments, i.e. the extensions 168 shown in FIGURE 10 and described above. To minimize this effect, it is desirable to use large rollers. Further, the tape thickness will differ somewhat from the design value and this will con- -tribute to positioning error. The positioning error due to tape thickness variation will vary with the square of the incremental angle of roller rotation for each character segment and with the square of the number of character segments. ~herefore this :
error is minimized by the use of a larger roller. It is prefer-red that the roller diameter be made approximately equal to the sum of the distance spanned by two window segments, i.e. ~
approximately~equal to twice the distance between the polnts of tangency ll and 12 ln FIGURE 2. This provides a tape segment '- ~ ~ . - . ' ' . .
~: ~ .. . . .
~0732~39L ;
angle of about ninety degrees or about four tape segments per circ~lmference.
Although an open-loop positioning system is advanta- :
geous in many respects, it does not provide absolu-te accuracy in positioning the tapes for the character displays. Accordingly, the foregoing features of character segment spacing and roller diameter are of great importance in producing charac~ers with faithful reproduction, especially where a large number of characters, for example forty or so, are represented in a single module. Additionally, the fidelity of character reproduc-tion is enhanced by proper selection of the number of segmentsper character. The number of segments per character shouId be - selected so that each horizontal bar in a character is provided by one, and only one, character segment; fur-therl such character segment should carry no portion of the character other than the - horizontal bar. With this arrangement, the upper and lower : edges of the horizontal bar necessarily occur at the crac~s between segments. It has been found that this requirement is fulfilled best with eight segments per character because it ~ permits proper relative positioning of the horizontal bars in all characters in all classes or fonts of character styles. It is - found that six segments per character does not permit proper placement of the horizontal bars without fragmenting a bar, with parts on two segments; ten segments per character is too many and horizontal bars would have to be fragmented to obtain proper placement.
In order to compensate for positioning errors of the character segments in displaying a given character, the appear ance of misalignment is minimized by fa.iring of the character ` ~ 30 segments at the upper and lower extremities thereof. This is ~`' ' ' : ' ' , ~` ,' ' ;.. ,' ' .
' '.' " "' ', ' '' ' ~,"'"'' ' ' .' .''''" ' ,', ' '";' ' ', ..'" :,. '' ' :' " '' 1C~732~
illustra-ted in FIGURE 10 which shows the character segments 33 and 34. In -these segments, for example, the charac-ter lines at the upper extremities 176 and at the lower extremi-tles 178 are faired toward the vertical direction, i.e the lines are diverted from the trend line of the character style to approach asymptotically a vertical line. Consequently, when two adjacent character segments are not accurately positioned the appearance of misalignment of the character trend line is minimized.
As described above, the driving rollers 15, 16, 17 and 18 are directly driven by the roller shafts and the slave rollers 19, 20, 21 and 22 are spring dri~en by the roller shafts to compensate for the disparity in the required angular - rotation for linear payout and uptake in transferring tape from one roller to the other. The driving rollers are positioned i~nediately behind the window segments and the driven rollers are immediately behind the driving rollers. Each pair of driving and slave rollers, being of a diameter approximately equal to two window segments, is accommodated in the space of the projected area of the respec~ive windo~ segments. This ~- ~ - . . .
- 20 enables-the module to be of compact design within a rectangular box havlng a height and width substantially equal to that of the window.
Reverting a~ain to the winding arxangement of the tapes, it is observed that the tape is always held ln tension by reason of the spring loading in the slave roller. It is dèsirable to maintain the tape tension at a value such that it will be stretched ~ightly across the display rollers but, o~ course, the spring loading varies with the amount of tape : ~
windup on the driving rollerO The spring loading is the smallest when most of the tape is on the slave roller and in this - . ~ .
:' ' - ' :
.
.
~73Z(~
P-305/~
condition the spring torque, working aginst -the friction in . ` the tape and roller system, may tend to allow the tape to become somewhat slack across the display rollers. This is overcome in the winding arrangement, as shown in FIGURE 4, by laying the loop of tape from the display rollers directly upon the driving roller. Note that for each set of rollers, the tape passes immediately from the driving ro:Ller over a first set of display rollers and thence is looped back over the driving roller in .
engagement therewith over more than 180 before it is passed over the second setlof display rollers to the slave roller.
This causes the driving roller to serve as.a feed roller and . obviates the need for idler rollers for looping the tape. As a feed roller it tends to keep the tape tigllt over the display rollers for both directions of rotation of the driving roller.
A modification of the invention is shown in FIGURES 11 ~ .... . . .
and 12. In this embodiment of the invention, the tapes are wound upon and displayed from the surfaces of the driving and slave rollers; the display rollers used in the embodiment of FIGURE 2 are dispensed with. Referring to FIGURES 11 and 12, the display module ~0 comprises a frame 82 and plural sets of-- driving and slave rollers. Each driving roller 8~, 85, 86 and : 87 is d.irectly connected with its respective shaft and carries : a gear 88, 89, 90 and 91 which lS fixedly connected therewith.
Each of the slave rollers 92~-93,~94 and 95 is spring loaded in the same manner as slave roller 19 described with reference.
.. . . :
to FIG~RE 5. Each of the slave rollers is connected through a ` . spring loaded-shaft with respective gears 96, 97, 98 and 99u An input gear 101 is manuallly operable by a crank lQ2 and is meshed directly with gear 97 of the~slave roller 93. All of the driving and:slave rollers are of the same diameter and all of . .
-22- .
.
~ .
'I Cli73ZO~
the gea~s, except the input gear 101, are of the sa~e size, It is noted that the rollers are of a diameter approximately equal to a single window segment of the display where a window.segment is that portion of the total display area which is allotted to a single character segment. A tape 103 has one end secured to the driving roller 84 and the other end secured to the slave roller 92, the tape being wound between the rollers in an "S" configura-tion. Similarly, a tape 10~ is connected between the driving roller 85 and the slave roller 93, the tape 105 is connected between the drivinglroller 86 and the slave roller 94 and the tape 106 is connected between the driving roller 87 and the slave roller 95. The various characters represented by the module are displayed successively by rotation of the input gear through successive an~ular increments of equal value.
Although the description of this invention has been ~iven with reference to a particular embodimellt, it is not to be construed in a limiting sense, many variations and modifications will now occur to those skilled in the art. For a definition of the invention reference is made to the appended claims~
.
' ' -. . , : .
.
.
. ~' . ' . - . .
:. , . . ' .
.
.
'' . ' .
' :' ~ " , ' ' ' ~
.
. ' ' ' . ' 23~
.
Claims (8)
1. A sign module for forming a display of a set of alphanumeric characters one at a time in a viewing window, said module comprising: a set of display tapes, each tape being imprinted on both front and back surfaces at discrete surface:
segments along its length with a discrete character segment of one character, all character segments on the front surface of a given tape corresponding to the same relative part of the respective characters, and all character segments on the back surface of a given tape corresponding to the same relative part of the respective characters, the number of display tapes in the set being equal to one-half the number of character segments, a driving roller and a slave roller for each tape connected with opposite ends of the respective tape and supporting the respective tape with one surface segment of each surface being displayed in said window at a segment thereof which is in posi-tional correspondence with the character segment represented, the surface segments on both surfaces of each tape being pro-gressively longer from one end of the tape to the other, the set of surface segments being displayed together in said window all bearing different character segments of the same character whereby an entire character is displayed, and means for dis-placing said tapes in unison along their length to successively present the character segments in registry with the respective window segments whereby the characters of said set are succes- .
sively displayed.
segments along its length with a discrete character segment of one character, all character segments on the front surface of a given tape corresponding to the same relative part of the respective characters, and all character segments on the back surface of a given tape corresponding to the same relative part of the respective characters, the number of display tapes in the set being equal to one-half the number of character segments, a driving roller and a slave roller for each tape connected with opposite ends of the respective tape and supporting the respective tape with one surface segment of each surface being displayed in said window at a segment thereof which is in posi-tional correspondence with the character segment represented, the surface segments on both surfaces of each tape being pro-gressively longer from one end of the tape to the other, the set of surface segments being displayed together in said window all bearing different character segments of the same character whereby an entire character is displayed, and means for dis-placing said tapes in unison along their length to successively present the character segments in registry with the respective window segments whereby the characters of said set are succes- .
sively displayed.
2. The invention as defined in claim 1 wherein the number of character segments is eight.
3. The invention as defined in claim 2 wherein the diameter of said rollers is approximately equal to the length of two character segments along the length of the tape.
4. The invention as defined in claim 1 wherein the character segments are nonuniformly spaced along the length of the tape whereby equal angular displacements of the driving roller causes successive character segments to be aligned with the respective window segments.
5. The invention as defined in claim 1 including a driving roller and a slave roller for each tape, one end of the tape being connected with the driving roller and the other end being connected with the slave roller, the diameter of each roller being approximately equal to the length of one surface segment along the length of the tape.
6. The invention as defined in claim 5 wherein the driving and slave rollers for all tapes in the set are disposed with their axes in the same plane.
7. The invention as defined in claim 6 including a driving roller gear connected with each driving roller and a slave roller gear connected with each slave roller, all gears being of the same size, the driving roller gear associated with any tape being in mesh with the slave roller gear associated with the same tape and one of the gears associated with each tape being in mesh with one of the gears associated with another tape.
8. The invention as defined in claim 1 wherein the means for supporting each tape comprises at least a pair of rollers with their axes parallel and defining a display plane which is tangent to the surface of said rollers, each of the rollers which define said display plane being disposed close to the adjacent roller to minimize the interruption between the imprinted character segments, each character segment being formed with lines at the midsection which conform to the con-figuration of the character font and being formed at the extremities of the character segment with lines which are faired asymptotically toward a line parallel to the length of the tape whereby the appearance of misalignment between adjacent character segments is minimized.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA316,422A CA1073204A (en) | 1975-12-03 | 1978-11-17 | Changeable printed alphanumeric display system |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/637,433 US4064503A (en) | 1975-02-03 | 1975-12-03 | Changeable printed alphanumeric display module |
| US05/637,434 US4067006A (en) | 1975-02-03 | 1975-12-03 | Changeable alphanumeric sign with opaque tape display forming segmented characters and words |
| CA245,005A CA1052096A (en) | 1975-12-03 | 1976-02-04 | Changeable printed alphanumeric display system |
| CA316,422A CA1073204A (en) | 1975-12-03 | 1978-11-17 | Changeable printed alphanumeric display system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1073204A true CA1073204A (en) | 1980-03-11 |
Family
ID=27425888
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA316,422A Expired CA1073204A (en) | 1975-12-03 | 1978-11-17 | Changeable printed alphanumeric display system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1073204A (en) |
-
1978
- 1978-11-17 CA CA316,422A patent/CA1073204A/en not_active Expired
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| MKEX | Expiry |