DATAVIEW DISPLAY SYSTEM

Figure 1. Diagram, Dataview Display Syste:m

BASIC CONCEPTS

Before examining the individual equipment elements, it may be of value to describe some of the basic concepts of DATA VIEW. The system is based, first, upon the philosophy of photo-optical quality and permanence, and, second, upon the doctrine of central image

generation with localized random access storage. A number of distinct advantages accrue from the concepts. Since an individ-ual display device contains a complete record in graphical format of the most current in-formation, as well as any special or historic data which may be of interest, loss of impor-tant electronic elements does not seriously disable the operator. Photo-optical tech-niques are superior in the realm of additive super-position, color rendition, brightness, resolution, geometric precision and large-screen capability. Furthermore, there is no requirement for electronic storage and high speed iteration in order to provide refreshed displays or to avoid flicker.

To implement the preceding rationale, a slide of the type illustrated in Figure 2 is utilized. There are two parts in the assem-bly: the image-bearing film material and the steel blade to which the film is bonded. On one edge of the blade are 30 teeth which are selectively removed for coding ... Clearance holes are provided in the steel so that regis-tration may be accomplished by means of a pair of film sprocket holes. The film used is Kalfax, a photolytic, daylight-handling emul-sion manufactured by the Kal var Corporation.

Kalfax positives, or bright-line images, are obtained by contact printing with a silver halide negative which produces any number of prints from a single data message.

A few words are in order with regard to the silver halide-Kalfax relationship in the system. Conventional photographic emulsions are highly sensitive since, at the time of ex-posure, the large silver halide granules present substantial capture cross-sectional areas to the incident photons. A high proba-bility exists, therefore, of capturing the one or few photons that may be required, even though not many are present. This condition implies low light levels, and hence high sen-siti vity. Each developed silver granule now absorbs a large amount of light to produce a dense optical image. The Kalfax emulsion, on the other hand, consists of a photolytic compound which yields volatile products, and which is dispersed in a polymeric vehicle.

Two photons, at least, are required for each photosensitive molecule which is considerably smaller than the corresponding silver gran-ules. The latent image results from internal stresses caused by partial volatilization of the compound. Upon subsequent exposure to

176 / Computers - Key to Total Systems Control

Figure 2. Dataview Slide Showing Teeth and Mounted Film

elevated temperatures, the polymer relaxes and an ordered reorientation and recrystalli-zation occurs corresponding to the pattern of the original stresses. These latter portions of the polymer scatter light to produce the desired visual image. Kalfax emulsions have a spectral sensitivity curve lying in the range of 350 to 440 millimicrons with a peak at 380 millimicrons. Minimum exposure of 1.6 watt sec/ cm ² followed by thermal development of 0.5 cal/cm 2 results in a density of 0.5 above background. Conventional, or silver halide, film emulsions possess the requisite orders of sensitivities and spectral range as well as high resolution, which allows a high quality record to be made from CRT screens. Since more than one copy of a given message may be desired for several display devices, it is convenient to produce prints from the initial negative. Kalfax may be rapidly exposed and

developed without the use of chemicals. Thus, it ~erves as an ideal copy medium.

The local slide storage inherent in the DATA VIEW system must provide a means to obtain information which is current and which may not be found in any given display device.

Currency may be maintained by immediate or routine updating of those slide files affected. A number of input equipments (which are beyond the scope of this paper) can be used to direct any available data to a request-ing console or large screen display.

The description of the primary elements in the system will serve to illustrate further how the basic concepts have been imple-mented.

DISPLAY GENERATOR

The Display Generator produces and dis-tributes finished slides. A block diagram of

Dataview, A General Purpose Data Display System / 177 the essential functions is shown in Figure 3.

Signal input is serial binary, with 8 bits per word to conform with Army FIELDAT A for-mat. Four words define completely anyone unique deflection position of the cathode ray tube spot, its luminance level, size, and other requisite data.

Since the electron beam in the CRT is po-sitioned by quadrature fields, eleven bits lo-cate a desired point in X and eleven bits in Y. A set of shift registers accumulate posi-tional information to be converted to analog deflection currents. An absolute accuracy and stability of one half of one location co-ordinate is achieved by eliminating driving amplifiers for the CRT deflection coils.

Digital to analog conversion is accomplished at power levels commensurate with deflec-tion requirements.

A minimum redundancy form of scanning is utilized. Location coo r din ate s are

specified at intervals which vary in accord-ance with the number of points necessary to adequately define a given line or curve. These points are integrated in the deflection circuits to produce smooth, continuous lines. Every data point is traversed only once in any given message, being immediately recorded by the camera assembly as it occurs. Where dis-continuities necessarily exist in the image lines, the electron beam is held cut-off, or blanked. The latter is the normal condition of the CRT; unblanking instructions serving to illuminate the screen when required.

Since the data rate is constant and the inter-coordinate distances differ to suit the fine line structure, a varying spot velocity results. Super-imposed on the latter is the non-linear velocity attributable to the inte-gration circuits which must achieve better than 99.9% of final value during the inter-coordinate interval. Compensatory intensity

,Figure 3. Diagram, Display Generator

178 / Computers - Key to Total Systems Control modulation is provided to offset both of the latter effects.

A focused spot, in the center of the CRT screen employed, measures approximately 0.001 inch. For this dimension, it does not seem advisable to obtain measurements by the shrinking raster method. As a first esti-mate, direct microscopic examination with a calibrated reticle has been very successful and correlates well with more refined tech-niques. By recording a number of line seg-ments on film, it is possible to obtain micro-densitometric curves rep res e n tin g the cross-sectional energy distribution in the excited phosphor. Line width is then defined by the half amplitude pOints. Critical focus is a non-linear function of deflection angle.

In order to preserve optimum definition, therefore, dynamiC focus is provided.

Variable line widths may be generated as required by the data formats for emphasis or other reasons. Ideally, the energy in the electron beam cross-section would be rec-tangularly distributed. The actual distribu-tion is approximately Gaussion. Defocusing to achieve wider lines would result in a loss of edge definition due to more gradual sloping of the distribution skirts. Instead, a high frequency circular motion is superimposed on the electron beam to effect a Lissajous pattern of predetermined amplitude. The re-sultant helical structure is so fine that it is not resolvable.

When all the ihformation intended for one slide has been t ran s mit ted, an end-of-message character actuates the slide proc-ess controls. The exposed negative film

Negative processing takes place by inject-ing, sequentially, relatively small amounts of developer, fixer, and wash. One fluid dis-places another by capillary action. A total fluid volume of approximately 11 cc is re-quired to achieve optimum image quality.

The chemicals used for each frame are com-pletely exhausted, and are drained off as waste. A jet of hot air removes the wash solution and dries the negative. The entire cycle requires between six and eight seconds, depending on the desired results. Full

development and fixing is obtained in approx-imately two seconds.

The developed negative consists of three major dark line image areas. First is the data which will appear on the display screens.

Lying just below this (and parallel to the long, or horizontal, axis) is an alphanumeric code for visual identification which has been also written by the cathode ray tube. Below the visual code is a series of 40 identifying light and dark areas used for machine reading.

The latter are sensed photoelectrically in the final negative station which immediately follows the capillary developing chamber.

Two conditions are established in accordance with the dot code: first is the number of positi ve slides to be made and their destina-tion; and second is the setting of a notching mechanism. A pre - mounted unexposed Kalfax slide is fed from a magazine into contact, with the negative, emulsion to emulsion. Ex-posure is accomplished by a pulsed xenon arc; then a heated platen is brought into con-tact with the Kalfax film base to develop the latent image. Two slides per second are thus produced until the programmed quantity is reached. As the positives are made, teeth are notched or removed from the metal car-rier to conform with the information contained in the photoelectric reader dots. Thus, each slide also carries a mechanical code denoting its identity. Finally, the negative is purged and the entire process is repeated for subse-quent messages.

SLIDE DISTRIBUTION

Housed within the display generator is a slide distribution module shown in Figure 4.

In reality, it serves two generators which occupy a single cabinet, and up to twelvedis-play devices may be served by a pair of gen-erators. One generator may be onor off-line as required. When a slide has been made, it is delivered to the distribution module and falls past a series of twelve deflecting gates.

The latter are pre-set at the time the nega-tive is examined photoelectrically. Each of the twelve gates is served by a pneumatic tube leading to an indi vidual console or large screen display. Each gate also has a local storage bin. A given slide is deflected into a tube or a bin depending on the pre-programmed condition of that channel. Upon being deflected, the slide is sensed and the gate is re- set so that the next slide may

Dataview, A General Purpose Data Display System / 179

Figure 4. Slide Distribution Module With Dataview Slide in Chute

proceed to the next intended channel. After the last scheduled slide is in place, air pres-sure is applied to the pneumatic tubes by means of a manifold. Delivery may also be scheduled for one specific channel or for any specific group of channels.

When the Kalfax is bonded to the steel carrier blade, a "propelling" flap is allowed to extend beyond the image area. Air pres-sure lifts the flap, partially sealing the tube as shown in Figure 5. Thus, an effective piston is created which causes the slide to move with the air stream. Velocities of 50 feet per second have been achieved, and ve-locities of 100 feet per second are clearly

feasible. The pneumatic tubing is a plastic extrusion which may be formed into tWists, bends, and compound shapes, to accommo-date every conceivable installation require-ment. Convenient lengths of tubing are held together by clamps which serve both for mechanical support and for air seal.

DISPLAY UNITS

Functionally, the console display and the large screen display are identical; both de-vices can therefore be described simultane-ously except for certain obvious differences in implementation. A ,block diagram of the display units appears as Figure 6.

A slide delivered to a console or a large screen display may contain tabulated infor-mation, syntactical inforinfor-mation, or data ref-erenced geographically to a map or other appropriate background. In any case, the recorded image consists of bright lines with a substantially black surround. Additive superposition of several overlays is thus feasible. Five optical apertures are provided.

One of these projects the map or other back-ground which may be in full color.

A single source of illumination is inter-cepted along two mutually perpendicular axes.

The console lamp is a 450 watt xenon arc.

The illuminant possesses a number of distinct advantages over incandescent sources. These are listed below.

1. Spectral energy dis t r i bu t ion very closely approaches that of the sun, thus improving color rendition.

2. Lamp life is over 1000 hours compared to perhaps 25 to 50 hours.

3. Lamp failure appears as a gradual re-duction in luminous output rather than an abrupt blackout.

4. Luminous efficiency is considerably higher.

5. Optical efficiency, due to the small arc Size, is substantially greater.

Color. separation for additive superposi-tion is obtained by dichroic mirrors rather than by absorption filters. Losses are thereby minimized. Four mirrors are arranged so that white a.l!~ nominal red, yellow, and blue light beams are--obtalned~- The band~passcharac­

teristics of the mirrors are selected so that the xenon arc spectral distribution is divided into segments of equal photopic brightness.

Each projected light beam may be changed in intensity at the control panel to suit individual

180 / Computers - Key to Total Systems Control

Figure 5. Slide in Pneumatic Tube Showing Erected Propelling Flap

BL.OCK DIAGRAM

DATAVI&W DISPLAY UNITS

Figure 6. Diagram, Display Units

preference or the nature of the data. It is interesting to note that choice of color for any given format may be forced by the slide code,or may be determinedby the operator's preference.

Those channels not in use may be dimmed to black. Three discrete colors, plus white, are directly available. However, by proper programming of the data messages, seven colors may be obtained through add it i v e superposition.

The slides, which are deliveredpneumati-cally tothe display unit, enter a magnetic re-ceiver. A manual insertion device is also a part of the receiver. Prior to being loaded into the main magazine or stack, the slide is inter-rogated by mechanical reading of the notched tooth code. One of several actions ensues:

1. If the arriving slide is a first issue of a given category, it is entered into the main stack.

2. If the slide is an updated version of a slide already in storage, the latter is purged and the new version is loaded into the main stack.

3. If the slide is a "special request" or is a type not normally stored by a given display unit, it is loaded into a small special storage bin; its presence is in-dicated on the control panel.

The slides are stacked between permanent magnets as shown in Figure 7. Self-alignment takes place in the magnetic field regardless of the number of slides present, up to the maximum capacity. No basic limitation in size exists, but to stay within over-all equip-ment limitations, the console display has been designed for approximately 1000 DATA VIEW slides and the large screen display for 2000 slides.

Dataview, A General Purpose Data Display System / 181

Figure 7. Partial View, Console Slide Storage and Transfer Mechanisms

Access for retrieval is essentially a ran-dom process, and is based on the keysort principle. Activating the desired decimal code at the control panel causes a series of corresponding keybars to be extended along the entire stack length. That slide which has been appropriately notched is free to move by one tooth pitch; all others are locked in place. The requested slide can then be with-drawn from the stack regardless of its posi-tion and without searching. Once extracted, the slide is picked up by a transfer mecha-nism which carries it to the intended projec-tor aperture. The entire retrieval action takes less than three seconds. When it is necessary to remove a slide from the files, either automatically or on manual command, it is transferred by the same action into the purge bin. The bin is emptied periodically, and its contents disposed of as required. A complete class of slides may be purged simul-taneously if necessary.

Maps or other reference backgrounds are stored and handled in a similar manner, but in separate stacks. The capacity of back-ground slide stacks is approximately 100 slides in the case of the console, and 750 slides in the case of the large screen display.

To achieve the high orders of total resolution encountered in many maps and aerial photo-graphs, 70 mm film is used instead of the DATAVIEW 35 mm size. Overlays andasso-ciated maps are coded to prevent improper pairing.

System distortions and _ indJ~idual regis-tration errors may contribute to an incorrect position being displayed in an overlay situa-tion analog. The percent error may be defined as:

E = 100 ad

w

a

d is the straight line distance between any image point, as displayed, and the theoretical, reference, or intended pOSition for the point;

W is the display width. There are a number of individual sources which contribute to the error E. These may be assumed to be ran-dom, independent, and normally distributed.

Under these conditions, an over-all three sigma value for E is 0.6% applied to a large number of DATA VIEW systems.

Due to the nature of the system, related adjacent image pOints which lie within a given character or symbol are mutually registered within 0.05% of the maximum symbol dimen-sion. Figure 8 illustrates a typical map and multiple overlay situation displayed on a console screen.

SERVO-CONTROLLED POINTER

Provision has been made for a dial tele-phone module on all display units. When com-municating with one another, operators of display devices may have occasion to discuss a situation analog of mutual lnt'erest. They will often find ^it necessa~y ~t.o point out the specific area in question ~on one or more re-mote displays. To accomplish this a servo-controlled reticle may be positioned anywhere on those display screens which are in tele-phonic contact.

Two frequency modulated carriers in the 300 to 400 cycle region convey a joystick po-sition signal over existing telephone lines.

The carriers-are purposely made audible, but kept at levels which will not impair intelligi-bility of the telephone conversation. Raising the joystick from the retracted pOSition actuates the reticle movement. A lockout feature prevents any other joystick from en-abling the deflection servos. Rate of response is high; there is no lag associated with rea-sonable human manipulation of the joystick.

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Figure S. Full Situation Analog Display on Console Screen

The pointer system on a display device may also be used for local briefings when a connection with remote units is not required.

This is particular ly valuable when a group of people in a single location are examining a complex presentation on a large screen,

This is particular ly valuable when a group of people in a single location are examining a complex presentation on a large screen,

Im Dokument COMPUTERS - KEY TO TOTAL SYSTEMS CONTROL (Seite 191-200)