1、INCH-POUND A-A-5 80% January 1, 1996 COMMERCIAL ITEM DESCRIPTION INDICATOR, ATTITUDE, THREE INCH, SOLID STATE, SELF-CONTAINED The General Services Administration has authorized the use of this commercial item description, for all federal agencies. 1. SCOPE. This commercial item description covers a
2、3-inch, solid state, self-contained attitude indicator intended to provide a standby attitude display for transport aircraft. 2. SALIENT CHARACTERISTICS. 2.1 Performance. 2.1.1 Accuracy. 2.1.1.1 Static Accuracy. The indicator, when connected and operating at standard “bench“ conditions, shall provid
3、e pitch and roll accuracies of h0.5“. 2.1.1.2 Dvnamic Accuracv. The indicator shall provide pitch and roll accuracies of h0.5“ when the aircraft is in steady state, unaccelerated, non-maneuvering flight. The pitch and roll error shall not exceed *3.0 during all anticipated normal and emergency fligh
4、t operations for a transport aircraft that is within the envelope of safe or recoverable flight. The supplier shall perform the tests and analysis necessary to veri that the indicator meets these accuracy requirements. Flight profiles that can be used in the analysis to veri the dynamic accuracy req
5、uirements are given in Appendix 2. 2.1.2 Remonse Time. The indicator shall achieve the required accuracy of *OSO within five minutes after power is applied when operating within the full environmental range specified in section 2.6. The indicator shall achieve 10.5“ accuracy after one minute of unac
6、celerated flight following a turn or acceleration. 2.1.3 Dvnamic Ranze. The instrument shall operate and display attitude through full 360 rotations in pitch and roll. There shall be not reduction in accuracy for all displayed angles. 2.1.4 Dvnamic Rate. The instrument shall operate when the aircraf
7、t dynamic rates are within the following limits: Roll Pitch Yaw 100 per second 75 per second 100“ per second 2.2 Controls. 2.2.1 W. A control shall be provided to reset the instrument to O“ pitch and O“ roll. 2.3 Display. The display shall meet the requirements of Appendix 1. Beneficial comments, re
8、commendations, additions, deletions, clarifications, etc. and any data which may improve this document should be sent to SA-ALC/TILDD, 485 Quentin Roosevelt Rd., Kelly AFB, TX 78241- 6425. FSC 6610 1 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- -
9、 - A-A-58055 74 OLb55 837 2.3.1 Displav Area. The minimum active display area shall be 2.25 by 2.25 inches. 2.3.2 Viewing Envelope. The display shall meet the requirements of Appendix 1 paragraphs 4.2.2.4 for luminance uniformity and 4.2.4.3 for chroma (perceived color) uniformity for the design eye
10、 positions and allowable head motion envelopes as given in Appendix 3. 2.3.3 DisDiav Ouality. The display shall exhibit viewing characteristics, line-width uniformity, symbol alignment, and symbol uniformity compatible with Appendix 1 paragraphs 4.1.1,4.1.2,4.1.6 and 4.1.7. The display shall exhibit
11、 no matrix anomalies, crosstalk, jitter, flicker, or symbol motion jerkiness as described in Appendix 1 paragraphs 4.1.3 to 4.1.9 2.3.4 Displav Resolution. The display shall contain a minimum pixel density of 80 pixels (color groups) elements per inch for matrix displays to avoid visual aliasing eff
12、ects. 2.3.5 Display Maximum and Minimum Luminance. The display should be capable of providing the maximum and minimum luminance levels under the conditions specified in paragraph 4.2.2 of Appendix 1. 2.3.6 DisDlav Contrast. The display should meet the contrast ratio requirements defined in Appendix
13、1 paragraph 4.2.3 in both dark and high ambient conditions. 2.3.7 Displav Temporal ResDonse Time and Tmaee Retention. The display shall meet the response time characteristics defmed in Appendix 1 paragraph 4.1.10 of a 70% perceived luminance to commanded luminance ratio over an update time period of
14、 1/30 sec. Furthermore the display shall exhibit no discernible after-image that could cause erroneous display interpretation as outlined in paragraph 4.1.1 1. 2.3.8 Disdav Defects. The display shall meet the defect requirements outlined in Appendix 1 paragraph 4. I. 12. No failed ON RowlColumns on
15、the display, no allowable failed OFF RowColumns within regions of significant displayed information. Design guidelines should follow techniques outlined in paragraph 4.1.12.4 in order to minimize effects of failed elements. Allowable failed sub-pixel elements will follow the recommended practices of
16、 Wright Lab WL-TR-93- 1 177 “Draft Standard for Color Active Matrix Liquid Crystal Displays (AMLCDS) in U.S. Military Aircraft” paragraph 4.2.2.3.13.1. No more than 0.01% of the sub-pixels on the display shall be defective. For a 240 x 240 pixel display with 2x2 sub-pixels per pixel, this correspond
17、s to no more than 23 pixels. No more than two of these allowable sub- pixel defects in the Failed-ON condition will be white pixels. Furthermore, adjacent failed sub-pixels, known as a cluster defect, will be limited in number to less than 2 Failed-ON clusters and 4 Failed-OFF clusters. A cluster de
18、fect in an area of critical information display is unacceptable and will result in the rejection of the display. 2.3.9 DiSDhv Sunlicht Readability. The display shall meet the symbology readability requirements of Appendix I paragraph 4.2.1 for ambient illumination levels incident on the display face
19、 ranging from 1.1 lux (O. 1 foot-candles) to a sun-shafting level of 86,100 lux (8000 foot-candles). 2.3.10 DisDiav Multiple Images. The display shall exhibit no multiple images due to off-normal incidence illumination that could cause erroneous interpretation of the displayed data. Baffling and ant
20、i-reflection filtering of glass surfaces should be employed to minimize the occurrence. The specular reflectivity of the display face shall be 1 fL for Measured Luminance 1 fL for Background Luminance 1 fL L*back = 116 3 - 16 L*back = 9.03 x Measured Luminance D6500 (u=O.1978, v=0.4684) is recommend
21、ed as the reference to insure uniformity from flight deck to flight deck. Another reference could be used to insure uniformity across a given flight deck providing the color is not objectionable. 4.2.3 Contrast Ratio (CR): The contrast ratio (total foreground luminance/total background luminance) sh
22、all be sufficient to provide a promptly discernible, easy to read image under all conditions of cockpit illumination and under all conditions of eye adaptation to the external visual scene. image brightness, the subjective perception of luminance, is heavily dependent on image size or line width. Sm
23、aller line widths than those referenced in the following paragraphs will require higher contrast ratios for comparable reada bi My. The following contrast ratio requirements apply only to skeletal-graphics or text display formats. Formats which present image video information or make extensive use o
24、f shading to code information may require higher contrast ratios. 4.2.3.1 should be a minimum of 20:l at the design eye position and 1O:l for any eye position within the viewing envelope. This requirement shall apply t self-luminous displays in a dark ambient or to transflective/reflective displays
25、subjected to a cockpit illumination of dark ambient to 100 fc. This requirement is based on a 0.6 mrad line width. For line widths of 1.2 mrad or greater, the average white contrast ratio at the design eye position should be a minimum of 15: I. Dark Ambient Contrast Ratio: The average white contrast
26、 ratio over the usable display surface 4.2.3.2 should be a minimum of 3:l for 0.6 mrad line widths and 2:l for 1.2 mrad line widths when viewed from any eye location within the viewing envelope. This requirement shall apply to self-luminous or transflective/reflective displays when subjected to poin
27、t source illumination levels up to 86 1 O0 lux (8000 fc). This requirement does not apply to specular reflections from point source illuminations. High Ambient Contrast Ratio: The average white contrast ratio over the usable display surface 4.2.4 Color: Displayed symbology shall be distinguished Fro
28、m its background and from the other symbols by means of luminance differences and/or chromaticity differences in all ambient conditions defined in 4.2.1. 16 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The most credible color difference system is
29、CIELUV which is described in Supplement 2 to CIE Publication No. 15; but it does not consider symbol size and does not offer criteria for perception. Except in cases where an absolute chromaticity is desired (e.g., Cyan for sky shading), colors should be selected which maximize color differences. Re
30、sults should be analyzed using the CIELUV system since this system perceptually weights both luminance and chromaticity components in determining color difference. Although there is no adequate basis for specifying a minimum acceptable difference at this time, chroma difference tolerances are recomm
31、ended to prevent generic color confusion when observing several LCD displays on the same flight deck. The chroma difference tolerances shown below are partitioned into three separate categories: a. Chroma difference between colors across the utilized display surface (4.2.4.1) b. Chroma difference be
32、tween specified colors and colors measured at the DEP (4.2.4.2) c. Chroma difference between DEP colors and colors anywhere in the viewing envelope (4.2.4.3) In no case shall the tolerances specified in the subparagraphs listed above act additively to prevent discrimination or proper interpretation
33、of symbols of different colors. A display not meeting these limits could be acceptable if analysis/testing of operational formats determine the distinguishability of the symbols. 4.2.4.1 dimming range (backlight and/or gray scale) shall have a chroma which is uniform across the utilized display area
34、 when viewed from the design eye position. The chroma difference (AC*fixed) between any two points on the screen of the same color when viewed from a fixed point should not exceed 24. Chroma Uniformity: A symbol of a specified color set to any intensity within the specified Where: AC *fixed = JAU *2
35、 +AV *2 And: Au* = Difference between measured CIE 1976 u* values Av* = Difference between measured CIE 1976 v* values U* = 13L*(u-O.1978) V* = 13L*(-0.4684) Measured Luminance for Measured Luminance I fL for Measured Luminance 1 fL 17 Provided by IHSNot for ResaleNo reproduction or networking permi
36、tted without license from IHS-,-,-L*measUred= 9.03 x Measured Design Eye Luminance for Measured Design Eye Luminance 1 fL Lu min ance Yn L* = 903 x for Luminance 1 fL Where the surround or object-color stimulus is specified as: 19 Provided by IHSNot for ResaleNo reproduction or networking permitted
37、without license from IHS-,-,- A-A-58055 = 9999974 0369973 852 5 3 4) COLOR BANDING (MATRIX). Nonuniform distribution of color within a line or symbol (see Figure White Line FIGURE 4 5 4 interaction of line or symbol orientation with pixel pattern geometry (see Figure 5). COLOR FRINGING (MATRIX): Col
38、or distortion along the edge of a line or symbol due to the i White Line FIGURE 5 L CONTRAST RATIO (CR): CR = 1 Lb 5.5 Lt is the total luminance of the symbol or image, including any transmitted and reflected light as measured in the specified lighting conditions. Lb is the luminance of the backgrou
39、nd, or dimmer area, including any transmitted and reflected light and any stray display emissions measured in the specified lighting conditions. See ARP1782 for a full discussion on this and related definitions. 5.6 CROSSTALK: Unwanted luminance modulation in display elements which is caused by the
40、cross coupling of electrical signals addressed to other elements or rows, columns, or blocks of other elements. 5.7 DESIGN EYE POSITION (DEP): A point fixed in relation to the aircraft structure (neutral seat reference point) at which the midpoint of the pilots eyes should be located when seated at
41、the normal position. The DEP is the principal dimensional reference point for the location of flight deck panels, controls, displays, and external vision (reference Figure 1 of ARP4101). 5.8 matrix LCD, the smallest addressable shutter of an individual color. In the case of a segmented display, any
42、of the shapes, or symbols made up of only one individual addressable entity. DISPLAY ELEMENT: The smallest addressable entity of the display. In the case of an active NOTE: Other commonly used terms are “dot“ in matrixed displays and “segment” in segmented displays. 5.9 “bright” or emitting state. F
43、AILED-ON: A display element, row, or column which is failed permanently or sporadically in the 5.10 FAILED-OFF: A display element, row, or column which is failed permanently or sporadically in the “dark” or nonemitting state. Provided by IHSNot for ResaleNo reproduction or networking permitted witho
44、ut license from IHS-,-,-5.1 1 FLICKER: Flicker is an undesired rapid temporal variation in display luminance of a symbol, or a group of symbols, or a luminous field. Flicker can cause fatigue and reduced crew efficiency. 5.12 GRAY SCALE: The incremental levels of display element light transmission w
45、hich exist between fully off (dark) and fully on (bright). 5.13 IMAGE RETENTION: Image retention is an undesired afterimage (residual pattern) that persists on the display. 5.14 INSTRUMENT: The word “instrument” shall be considered to mean the specific unit or complete system for which this appendix
46、 is written. 5.15 JITTER: Unintended rapid movement discernible to a human eye located at the design eye position. 5.16 LINE WIDTH: Width at 50% of peak luminance of the line luminance distribution when measured from the DEP. 5.17 LUMINANCE: A measure of luminous intensity per unit area; units are c
47、andela per square meter (cdim2) or foot-lamberts (fL) (reference ARP4260). 5.18 MILLIRADIAN (mrad): An angular measurement equal to 0.0573 degrees defined as one thousandth of an arc whose length equals the circle radius. Table 1 converts milliradians to linear dimensions (inches and millimeters) fo
48、r a viewing distance of 762 mm (30 in). 5.19 MOIRE: A pattern seen when two out of phase spatially periodic patterns are superimposed. 5.20 PIXEL: In a matrix display, the smallest group of display elements which provides the color capability of the display. NOTE: Be careful with the word “pixel”; i
49、t is sometimes erroneously used to refer to a single “display element” on a color matrix display (see 5.8). 5.21 RACHETING: Discontinuous (jerky) movement or rotation of a dynamic display feature caused by excessively large quantization steps in the translation or rotation of the particular feature. 5.22 ROPING: Periodic luminance modulation along a line producing a “rope-like” appearance. 5.23 SEGMENTED DISPLAY: A display in which the individual addressable di
