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Ergonomics

ISSN: 0014-0139 (Print) 1366-5847 (Online) Journal homepage: http://www.tandfonline.com/loi/terg20

Touch Displays: A Programmed Man-MachineInterface

E. A. JOHNSON

To cite this article: E. A. JOHNSON (1967) Touch Displays: A Programmed Man-MachineInterface, Ergonomics, 10:2, 271-277, DOI: 10.1080/00140136708930868

To link to this article: http://dx.doi.org/10.1080/00140136708930868

Published online: 25 Apr 2007.

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BlackBerry Exhibit 1016, pg. 1

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Touch Displays: A Programmed Man-Machine Interface

By E. A. JOHNSON Royal Radar Establishment. RIalvern

1. Introduction A very large number of so-called automatic data-processing systems require

the co-operation of human operators to achieve satisfactory operation. In many of these systems i t is necessary to reduce operator reaction time to a minimum, which in turn demands an arrangement where the man-machine communications are optimized. This requires that the methods of presenting information to, and receiving instructions from, the operator should be rapid and easy.

2. The General Problem of Man-Machine Communication For the presentation of information to the operator the system generally

used is some form of printing, usually electro-mechanical. Although the normal teleprinter output is rather slow in relation to the speed with which an operator can absorb information, an extension of the technique t o line printing can overcome this. Alternatively an Electronic Data Display can be, and is, used and in both cases the ' output mechanism ' from the computer system does not really add significantly to the time required for an operator to accept information. There is also a considerable amount of flexibility of format available to ease understanding.

The situation is not so satisfactory in the case of accepting instructions from an operator. The normal method is to make use of some form of keyboard with either a standard set of alpha-numeric keys and/or some special keys, usually called function keys. The latter, as their name implies, usually provide control instructions to the system, whilst the alpha-numeric keyboard is used to input information, interpreted by the system in accordance with the most recent control instruction. The process can be rather slow and clumsy especially when a fairly large system is involved with each operator having a wide range of input possibilities in the interests of flexibility.

The idea of the Touch Display was conceived a t R.R.E. in an attempt to overcome the limitations in man-machine communications indicated above. It was originally put forward in the context of an Air Traffic Control Data- processing System for which i t has clear application, but i t is felt that the arrangement has much wider application; in fact, to the whole field of data- processing systems.

3. General Principles of Operation The first idea underlying the design and operation of the Touch Display

is that, no matter what the overall and complete range of possible signals from an operator might be, a t any one time the signal actually sent by the operator to the data-processing system will be one chosen from a strictly limited range. For example, the signal might be, and often is, one of the 10 numerical digits. Probably one of the widest range of choice actually

BlackBerry Exhibit 1016, pg. 2

E. A. Johnson

exercised would be to select one from the 26 available alphabetic characters. Secondly, in order that the data-processing system should be able to interpret the signal correctly, it must know from what range of possibilities' it has been chosen and also what consequences must stem from that choice. This ' knowledge ' within the computer can therefore be used to restrict the range of choice available to the operator a t any given time to just those possibilities which are relevant to his present task. Subsequent to any input signal being received, the system can alter the range of choice as and when required. This control is, of course, exercised by the computer programme in the system, and in consequence the operation of the Touch Display system can be described as ' Programmed Control '.

One very significant consequence of this control is that the scope for operator errors, especially errors of omission, is much reduced.

Another idea, possibly the most significant, underlying the design of the Touch Display is that the ' meaning ' given by the system a t any time to the ' keys ' available to the operator can be made easy to interpret. That is, the ' label ' attached to the keys need not be fixed, as in the case of alpha- numeric keyboards for example, but can and should be changed by the system computers in accordance with the required meaning a t any time. The effect of this idea is far-reaching. Not only does it allow the number of ' keys ' to be very limited whilst retaining a large measure of flexibility in their interpretation, but also it allows the ' meaning ' of a key to be changed as a result of information previously input to the system. A particular example, given later, is where one meaning attached to the keys is that of the ' call signs ' of the aircraft under.contro1 of a given operator. These, of course, change quite often and normally consist of up t o seven alpha-numeric symbols. By labelling ' keys ' in this way, communication with the system for a particular aircwft can be established in a single operation.

4. Technical Details of the Touch Display The first requirement of a system based on the ideas outlined above is a

flexible display system, capable of presenting the possible choices to an operator. Such a possibility is clearly available in an electronic data display for many applications. An extension to provide some form of graphical display may be desirable in certain cases. The second requirement is then to provide sensitive areas of the display screen which are capable of producing a signal when touched by a bare finger. Such an arrangement is described belo\p. A description of the Electronic Data Display system is not given since the techniques are well known and the precise method by which the display is produced is irrelevant to the operation of the system, beyond the need to satisfy the requirements of being able to change the display rapidly and to be able to position the data correctly on the display tube force.

To providc the sensitive areas, an electronic system has been devised'by which the computer can be informed that an operator is touching an electrical contact, a so-calIed ' touch-wire '. This touch-wire is completely passive mechanically and is, typically, a short length of 20 S.W.G. tinned copper wire let into a groove in the surface of a perspex mask over the surface of the display. Connection is made to the touch-wire by very thin wire retained in grooves on the undersurface of the mask. Use is made of the self-capacity

BlackBerry Exhibit 1016, pg. 3

273

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BlackBerry Exhibit 1016, pg. 4

274 1. A. Johnson

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Figure 2. A typiael amendment aequence.

BlackBerry Exhibit 1016, pg. 5

Touch Displays: a Programed Man-Muchine Interface

S K I 0 1 E G L L

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B P K M - 8 C L A R E C O S 2 3 x 1 6 0 9 x

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9 9 0 2 4 0 X X - 0 6 -

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T Y P E C F L R F L L l R P A T 7 BOO 2 4 0 X X - BPK M - B C L A R E C 0 5

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1 I Figure 2 continued. A t,ypicel amendment sequence.

BlackBerry Exhibit 1016, pg. 6

276 E. A. Johnson

system to step. To provide against possible errors one of the touch-wires is interpreted to mean ' stepback one in the sequcnce ' allowing correction of m y error. In practice this is rarely needed, the system providing an accurate, rapid and natural process.

In all the cases so far examined a system of 16 touch-wires has proved adequate, but should there be a need to use this facility to inspect alpha- numeric data in a control sequence it would be necessary to provide 32 touch- wires by extending the existing circuitry. Since the increase is largely to cater for the single-character letter input, the extra wires can be fitted a t close spacing and not used unless required by the particular control sequence.

From an equipment point of view there is, of course, an advantage in keeping the number of wires to a reasonable minimum. It has been suggested that there may be a need for a much larger matrix of wires, e.g. 256. If so, the most promising line appears to be a double set of touch-wires in which bottom and top elements are parnllcl connected in rows and columns. Rows and columns are separately detected, a.nd when both give a signal an output is obtained. I n this case resistive coupling by the finger may overshadow the capacitive effect. In general, however, the author is firmly of the opinion that sequential selection from limited lists is the prcfcmblc and usudly possible approach. '

5. An Example in an Air Traffic Control System The example is of the amendment of flight plans, and to simplil) t l ~

description we will assume these amendments arise as a result of n die tdc- phone report from the aircraft.

Thc scquence of events is as follows. Firstly, in the rest condition, i.e. between amendments, the computer

' knows ' that the next action of thc controller must logically be to refer to a particular aircmft. The computer already has the ca,ll signs of all the aircraft in the sector; i t therefore displays these call signs, one against each touch-wire.

Secondly, when the aircraft calls and identifies itself by its call sign, the controller touches the wire against that call sign.

Note the extreme simplicity of this action compared with typing in the five to scven characters involved, or even with the reading. off and injecting of the number of the line on which the call sign is shown on an electronic data display.

'J.'he computer now knows which aircraft is involved and knows, too, that the controller must next specify which item of the flight plan is to be a,mended.,

The computer therefore displays on the top half of the touch-display the call sign selected fo.1 lowed by the items of the flight plan. Each item consisting of its ' name ', and under the ' name ' the ' d u e ', and against thc touch- wires the computer displays the names of items, the pattern of the arrangement of the items being made the same as in the flight plan displayed above.

The controller selects an item by touching the wire and the computer responds by marking the selected item and offering to the controller, against the touch- wires, the list of possibilities for the first character of the ' value '. If i t is a numerical value the digits 0 to 9 may bc offered, but if the first digit is limited, ' as for a time in minutes to 5, then only 0 to 5 need be offered. On the other. hand, if the value is a symbol, then the appropriate symbols can be offered.

BlackBerry Exhibit 1016, pg. 7

Touch Displays: a Progwt r r t wed illaz-Xachine Interface 277

The controller selects the cbnlxctw and the coniputer inserts this in the flight plan under the first character uf the old \-due of the item, and then, if the value consists of more than one character, the computer presents the possibilities for the next character and so on, until the new value of the item has been built up and displayed u n d ~ r the old value.

Tlrc computer then asks the controller by words against the touch-wires if this nc\rr value is to be ' executed ' or ' ignored '; the controller inspects the old and the new values to see if the new value appears correct ntid credible and, if so, by touching 'execute', instructs the computer to incorporate the new value.

The computer then puts the display bnck to the initial reset condition to await bhe arrival of a new amendment.

Various refinements can be added; for instance, ' back-step ', ~vhich ca.ncels the previous input and restores the display to the previous condition, thus giving a. quick way of correcting input errors.

According to the amendment required the sequence can vary. One in particular \vhich deserves special mention is the sequence for cancelling s flight plan. It is, of course, very important that this does not happen by error, and so \\-hen the controller uses the touch-wire labelled ' ERASE ', the computer is programmed to present the words ' CONFIRM ERASURE OF KL104 ' for exnmple. This illustrates the way in which the touch display can be used to alert the controller a t critical phases in operation.

Of course other possible applications exist, and if the display process has adequate flexibility to present solutions to a problem pictorially, then by appropriate labelling of the touch-wires corresponding to the solution the choice can be indicated by a single operation. Again, another interesting possibility is the case of rarely used procedures; for example, ' EMERGENCY '. Here the instructions can be presented in plain laguage, e.g. ' alert fire brigade ', ' you must now choose to do . . . or to d o . . . ' and so on. The computer ensures that not only does the controlIer clearly understand what is to be done, but ensures that no omissions occur.

6. Conclusion A number of models of the'Touch Display have been built for evaluation and,

as a result of experiments comparing their use with more conventional keyboards i t has been shown clearly that the use of the Touch Display provides both a faster and more accurate means of communicating between an operator and a data-processing system. One of the significant advantages is that only the computer programme affects the interpretation and labelling of the ' keys ', and consequently equipment provision and installation can proceed without hazard, even though final decisions on the ' labels ', etc., have not been taken. The Touch Display will be used in the Air Traffic Control Data- processing Systems in the U.K. and i t is firmly believed that i t will find wider application in other systems.

@ Crown Copyright. Reproduced by permiseion of the Controller of Her Majesty's Stationery Office.

BlackBerry Exhibit 1016, pg. 8