Dec. 18, 1962 W. R. SLOAN 3,069,681 SYSTEM FOR LARGE-AREA DISPLAY OF TWO-COLOR INFORMATION Filed March la, l960 3 Sheets-Sheet 1. r LIMAS9.NIHO BOHABO ??31=== IWWBO-BNI-NOI.-OL SV78EWIlCJE OMAJ.*JOTOO NOJIVW&JOHN? MABIA9.NI BOV-38ñS [] [] INVENTOR. WILLIAM R. SLOAN BY ????????? ? ???? AT TORNEYS Dec. 18, 1962 W. R, SLOAN 3,069,681 SYSTEM FOR LARGE-AREA DISPLAY OF TWO-COLOR INFORMATION Filed March 14, 1960 3. Sheets-Sheet 2 GN2&#OTOO ea? ?——?? AT TORNEYS Dec. 18, 1962 W. R. SOAN 3,069,681 SYSTEM FOR LARGE-AREA DISPLAY OF TWO-COLOR INFORMATION Filed March 14, 1960 3 Sheets-Sheet 3 – E. T =-4 HORIZONAL ? SWEEP GENERATOR 44 68 256 K.C. GENERATORPULSE ( BSTABLE BSTABLE B|STABLE ? B|STABLE BSTABLE ??? ? ??82 m232 -- 198 lost 3 -- SAS JS JAAYeASeSYe SAuSJSJASJLLLTLTMSTTLTTTLLLSLLSS LL LLL LLLLLL DISPLAY SURFACE HORIZONTAL SWEEP GENERATOR INVENTOR. WLLAM R. SOAN ATTORNEYS 3,069,681 United States Patent Office Patented Dec. 18, 1962 2 3,069,681 when the electrodes are respectively pulsed. Each of the SYSTEM FOR LARGE-AREA DISPLAY OF pluralities of electrodes is in spaced-apart alignment along TWO,-COLOR ENSFORMATION one dimension of the sheet and the two pluralities of William R. Sloan, Fort Wayne, Ind., assignor to Inter electrodes are respectively spaced-apart along the other national Telephone and Telegraph Corporation dimension of the sheet. Means are provided for moving Filed Mar. 14, 1960, Ser. No. 14,743 the sheet with respect to the electrodes along the other 9 Claims. (Cl, 346-74) dimension. First switching means is provided sequen tially coupling the first electrodes to the converting means This invention relates to a system for presenting in for sampling one of the color-responsive signals at dis two colors alpha-numeric information, i.e., words and Crete intervals and for pulsing the first electrodes respon numbers, and graphical information, such as maps, sive to the presence of the one color signal at the respec graphs, etc., visually on a large-area display for group tive intervals. Second switching means is provided viewing. sequentially coupling the second electrodes to the con There are occasions when it is desirable visually to Verting means for sampling the other of the color display various types of printed and/or graphical infor responsive signals at discrete intervals and for pulsing mation on a large-area surface to permit viewing thereof the second electrodes responsive to the presence of the by a number of persons, and it may further be desirable other color signal at the respective intervals. First and to display Such information in two separate colors, e.g., Second means for applying charged toner material of two black and red. In the past, such large-area displays have different colors respectively are provided, one color being been provided by conventional optical projection tech 20 applied to one side of the sheet and the other color niques which generally required a darkened room for being applied to the other side of the sheet. Thus, the optimum viewing and further involved substantial power first sequential switching means and its associated toner requirements. Furthermore, in instances where the alpha applying means may form black dots on the outer sur numeric or graphical information to be displayed is in face of the dielectric sheet while the second sequential the form of coded electrical characteristics, optical pro 25 switching means and its associated toner applying means jection requires the intermediate step of printing the may form red dots on the inner surface of the sheet. information before it can be optically projected, and like The red toner material applied to the inner surface of wise, graphical information conventionaily requires trans the sheet will, of course, adhere to the incremental fer to a transparency for best optimum projection. charged areas formed by the first switching means; how In application Serial Number 18,008, filed March 28, 30 ever, they will be masked by the opaque black toner 1960 of Eugene S. Hawkins, which is assigned to the material previously applied to these incremental areas assignee of the present application, there is described a on the outer surface of the sheet, Thus, the rod dots system for large area display of alpha-numeric and formed on the inner surface of the sheet will be visible graphical information which does not employ optical for viewing through the transparent sheet only in those projection techniques. In accordance with the invention 35 areas where incremental charges were not formed by the of that application, a printed page or a rectangular graph first switching means and first electrodes. ical display is divided into a matrix comprising a pre The above-mentioned and other features and objects determined number of discrete dots, the number depend of this invention and the manner of attaining them will ing upon the resolution required, e.g., much in the nature become more apparent and the invention itself will be of a newspaper half-tone. Thus, the area to be viewed 40 best understood by reference to the following description is divided into incremental areas, such as 1,000 dots of an embodiment of the invention taken in conjunction horizontally and 1,000 dots vertically to provide a poten with the accompanying drawings, wherein: tial of 1,000,000 dots. In order to display the infor F.G. 1 is a schematic illustration in block diagram mation in dot form, the horizontal dimension of the form showing the fundamentals of my invention; display surface is divided into a number of discrete FIG. 2 is a side-elevational view of the display means incremental segments and one horizontal line of the 45 of FIG. 1; alpha-numeric or graphical information is formed by FIG. 3 is a block diagram illustrating one embodiment sequentially scanning the line and forming dots where of my invention for presenting alpha-numeric information marks are required. Thus, the horizontal dot-forming in two colors, and mechanism and the display surface are moved vertically 50 FIG. 4 is a schematic illustration showing the preferred with reference to each other as scanning is repeated to embodiment of the dot-switches employed in FIGS. 1 form a rectangular display, much in the nature of a and 3. television raster. In the preferred embodiment of the Referring now to FIGS. 1 and 2 in which the broader above-referred to Hawkins' application, the display sur aspects of my invention are illustrated, my improved sys face is in the form of an endless belt of dielectric mate 55 ten for large-area display of alpha-numeric and graphical rial and the dots are formed by well known xerographic information, generally identified at 10 comprises converter techniques. 12 which receives the alpha-numeric or graphical in The system described and illustrated in the aforemen formation and converts the same into a first time-based tioned Hawkins' application displays information in only electrical signal having characteristics respectively respon one color, and therefore it is an object of my present 60 sive to the information in the two colors. If alpha invention to provide a system of the general type dis numeric information is to be displayed, the input informa closed in the Hawkins' application for displaying infor tion may be in digital form, i.e., a pulse code from a mation in two colors. computer or teletype coded as to character, position and In accordance with the broader aspects of my inven color. Converter 12 would then include means for tion, therefore, I provide means for receiving information decoding the digital input to identify the particular char and for converting the same into two time-based signals 65 acters, their respective locations on the page to be respectively responsive to the information in the two displayed, and their respective colors. Converter 12 will colors. The display surface is in the form of a rela also include a character generating device, such as a tively, thin sheet of transparent dielectric material and monoscope tube, for providing a time-based video signal means including first and second pluralities of electrodes corresponding to the input character. Since the input rate are provided cooperating with the dielectric material sheet 70 of the System 10 may be considerably faster than the to form incremental electrostatic charges in dot form printing rate, it will also be desirable to provide storage 3,069,681 3 4. means in converter 12 to store the character-responsive The first color toner applicator 66 is provided spaced signals for subsequent reading-out at a “slower speed con from printing heads 36 in the direction of movement 34 sistent with the capabilities of the printing apparatus. of belt 22 and is arranged to apply a first color charged The signals may be stored in the storage means at two toner, for example black, on the outer surface of dielectric different levels responsive to the two different input colors, 5 belt 22. A second color toner applicator 63 is spaced and likewise subsequently read-out at two different levels. from printing heads 33 in the direction of movement 34 Graphical information may also be in coded digital form, of belt 22 and is arranged to apply a second color charge or may be fed directly into the system in the form of toner, for example red, on the inner surface of the dielec X-Y voltages at levels corresponding to the two colors. tric belt 22; it will be observeci that the first color toner The first time based signal provided by the converter 10 is applied to the outer surface of run 28 of belt 22 whereas 12 is fed to a signal separating circuit 14 which separates the Second color toner is applied to the inner surface of the first time-based signal into two time-based signals run 38 of belt 22 so that it is not required to make contact respectively corresponding to the two color characteristics with the rollier 24.