ISO-268-1980.pdf
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1、International Standard 268 INTERNATIONAL ORGANIZATION F.OR STANOARDlZATlONWdEYHAPOHAR OPt-AHl43AUMR n0 CTAHAPTH3AUMM.ORGANISATlON INTERNATIONALE DE NORMALISATION ANST Tnterncrf Dw sodt Aircraft - Mechanical and electromechanical indicators - General requirements Akonefs - Instruments de bord mtkaniq
2、ues et 4ectromkcaniques - Caracth stiques g the specified accuracy requirements being maintained in any attitude. Any limitations of mounting attitudes shall be declared by the manufacturer. 5.2 The individual specification shall state the normal moun- ting attitude at which the indicator is to be c
3、alibrated. 6 Indicator movements 6.1 Indicator movements shall be securely fixed to the body of the indicator in such a manner that any distortion by connec- tion or mounting of the latter does not affect the accuracy of indication. 6.2 The design of an indicator and the form of its input infor- mat
4、ion shall ensure that each value of the input parameter results in a unique indicator reading (for example, two-speed synchros have been made to avoid ambiguity in the display and transmission of altitude information). 6.3 Stops shall be fitted to indicator movements where otherwise the display woul
5、d be able to move beyond the end of the scale to positions that result in erroneous readings. These stops shall be operative above or below the maximum and minimum scale graduations respectively, but shall be such that the direction from which the display is deflected is still ap- parent. 6.4 The de
6、sign of indicator movements shall be based on the following general principles : 6.4.1 Indicators shall accurately and smoothly follow changes of input and emergency conditions. 7.1 General 7.1.1 The indicator shall present the required information concisely and with a degree of precision compatible
7、 with the indication required and with the sensitivity of the movement. The data presented shall be prime, that is, no further operation upon it shall be necessary apart from simple factoring. The units in which information is presented shall comply with the requirements of the individual specificat
8、ion. 7.1.2 The design and purpose of the display shall be clear and unambiguous and such that it cannot resonably be confused with other types of display likely to be used with it. In par- ticular, for scales in excess of 360 with a single pointer, suitable means shall be provided to prevent ambigui
9、ty. Single channel, concentric, multi-pointer displays (for example, 3-pointer altimeters) should be avoided. 7.1.3 Indicators shall be designed so that parallax effects and tunnel (marking) effects do not interfere with reading of the indicator, to the degree of precision appropriate to the func- t
10、ion(s) being displayed, when viewed from angles up to 4o” to a perpendicular axis through the centre of the display face. 7.1.4 Manufacturers name, symbol or part number or other information not essential to the function(s) being displayed shall be unobstrusive if marked on dialfaces or instrument b
11、ezels. 7.1.5 If a display has both a pointer and counter presentation, care shall be taken to reduce masking of the counters by the pointer to a minimum. 7.1.6 If the indicator is luminous, the treated area shall be kept to a minimum compatible with ease of reading. (See 10.2.2.) 7.2 Scales and coun
12、ters 7.2.1 Figures and graduations shall be restricted to the minimum number compatible with the accuracy of reading re- quired. Markings shall be white on a black background unless markings or areas of other colours are required, in which case the colour specification shall be agreed with the indiv
13、idual manufacturer. All coatings used shall have a mat finish. IS0 268-1980 (El 7.2.2 For circular scale displays, the values shall increase in a clockwise direction. For strip (straight scale) displays, the values shall increase from bottom to top or from left to right. 7.2.3 Where necessary to ach
14、ieve the required reading accuracy over a certain pa? of the scale, non-linear scales may be employed provided that linear visual interpolation does not reduce the reading accuracy below the required system accuracy. Unless otherwise declared by the manufacturer, indicators with non-linear or indivi
15、dually-calibrated scales and having the same part number shall be designed so that the scale numbers and divisions of the working range are in geometrically similar positions. Over those parts of the scale which are operationally important, graduations shall represent equal increments of the indicat
16、ed quantity and visual interpola- tion shall be possible. The tolerances governing these general requirements shall be as given in the individual specification. 7.3.4 If settable indices or limit pointers are incorporated, they shall be of conspicuous colour pattern so that they are easily recogniza
17、ble and cannot be confused with the main in- dication. It shall not be possible, under any conditions, for the index or limit pointer to foul the main pointer(s) or any part of the main display(s). 7.3.5 The design of main pointer, settable indices and limit pointers shall be such that pointer coinc
18、idence is clearly defin- ed, 7.3.6 Except where otherwise permitted by the individual specification, the direction of movement of the controls operating indices or pointers shall be clockwise or forward for increasing values of the controlled parameter. 7.4 Failure warning indication 7.2.4 Sufficien
19、t scale numerals shall be marked on the dial to avoid or reduce the misreading by a complete scale division. These numerals, located against major scale markings, shall in- crease in single units, in twos, in fives or in decimal equivalents, except where for operational reasons (for example, the tak
20、e-off range of airspeed indicators) it is necessary to have a higher discrimination and the individual specification requires alter- native increments. 7.4.1 Where possible, a failure indication shall be provided on the face of the indicator whenever the information displayed is incorrect or unrelia
21、ble. The failure indication shall be a distinc- tive warning flag which, where practicable, shall obscure the failed information, or a light, or a combination of both. Indica- tions of an oscillating or flickering nature shall not be used. 7.4.2 The design and presentation of the indication shall be
22、 7.2.5 The oreferred smallest scale interval which is marked but has no n umeral against it shall represent one, or two or five units, or any decimal factor of such units. based on the following general principles : 7.4.2.1 The indication shall be easily recognizable by virtue of size, shape and col
23、our. 7.2.6 If a rotating drum digital display is incorporated in the presentation, the higher digit shall appear above the lower digit, that is the digits shall move downwards for increasing values. Counter indicators shall be provided with a means of ensuring that a complete number is always visibl
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- ISO 268 1980
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