1、Designation: E 1336 96 (Reapproved 2003)Standard Test Method forObtaining Colorimetric Data From a Visual Display Unit bySpectroradiometry1This standard is issued under the fixed designation E 1336; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe fundamental procedure for characterizing the color and luminance of a visual display
3、unit(VDU) is to obtain the spectroradiometric data under specified measurement conditions, and fromthese data to compute CIE chromaticity coordinates and absolute luminance values based on the 1931CIE Standard Observer. The considerations involved and the procedures to be used to obtain precisioncol
4、orimetric data for this purpose are contained in this test method. The values and procedures forcomputing CIE chromaticity coordinates are contained in Practice E 308. The procedures for obtainingspectroradiometric data are contained in Test Method E 1341. This test method includes somemodifications
5、 to the procedures given in Practice E 308 that are necessary for computing the absoluteluminance values of VDUs. This procedure is intended to be generally applicable to any VDU device,including but not limited to cathode ray tubes (CRT), liquid crystal displays (LCD), and electrolu-minescent displ
6、ays (ELD).1. Scope1.1 This test method prescribes the instrumental measure-ments required for characterizing the color and brightness ofVDUs.1.2 This test method is specific in scope rather than generalas to type of instrument and object.1.3 The values stated in SI units are to be regarded as thesta
7、ndard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Refere
8、nced Documents2.1 ASTM Standards:E 284 Terminology of Appearance2E 308 Practice for Computing the Colors of Objects byUsing the CIE System2E 1341 Practice for Obtaining Spectroradiometric Datafrom Radiant Sources for Colorimetry22.2 CIE Publications:Publication CIE No. 18 Principles of Light Measure
9、ments3Publication CIE No. 15.2 Colorimetry, 2nd ed., 19863Publication CIE No. 63 Spectroradiometric Measurement ofLight Sources, 198432.3 IEC Publications:Publication No. 441 Photometric and Colorimetric Methodsof Measurement of the Light Emitted by a Cathode-RayTube Screen, 197443. Terminology3.1 T
10、he definitions of appearance terms in TerminologyE 284 are applicable to this test method.4. Summary of Test Method4.1 Procedures are given for obtaining spectroradiometricdata and for the calculation of CIE tristimulus values and othercolor coordinates to describe the colors of VDUs. Modifica-tions
11、 to the standard calculation procedures of Practice E 308are described.5. Significance and Use5.1 The most fundamental method for obtaining CIE tris-timulus values or other color coordinates for describing thecolors of visual display units (VDUs) is by the use of1This test method is under the jurisd
12、iction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.06 onAppearance of Displays.Current edition approved July 10, 2003. Published July 2003. Originallyapproved in 1991. Last previous edition approved in 1996 as E 1336 96.2Annual Book of ASTM Stand
13、ards, Vol 06.01.3Currently available through the U.S. National Committee of the CIE, c/o Mr.Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 Pond Street, Salem, MA01970-4819.4Available from International Electrotechnical Commission (IEC), P.O. Box131, 1211 Geneva, 20 Switzerland. Electronic mail:
14、 dniec.ch.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.spectroradiometric data. (See CIE No. 18 and 63.) These dataare used by summation together with numerical values repre-senting the 1931 CIE Standard Observer and normalized to
15、 Km,the maximum spectral luminous efficacy function.5.2 The special requirements for characterizing VDUs pos-sessing narrow or discontinuous spectra are presented anddiscussed. Modifications to the requirements of Practice E 308are given to correct for the unusual nature of narrow ordiscontinuous so
16、urces.6. Requirements When Using Spectroradiometry6.1 When describing the measurement of VDUs by spectro-radiometry, the following must be specified:6.1.1 The radiometric quantity determined, such as theirradiance (W/m2) or radiance (W/m2-sr), or the photometricquantity determined, such as illuminan
17、ce (lm/m2) or luminance(lm/m2-sr or cd/m2). The use of older, less descriptive namesor units such as phot, nit, stilb is not recommended.6.1.2 The geometry of the measurement conditions, includ-ing, whether a diffuser was used and the material from whichit was constructed, the distances from the VDU
18、, the size of thearea to be measured on the VDU, the uniformity of the VDUacross the area to be measured, the microstructure of the VDUpicture elements, and the presence of any special intermediateoptical devices such as integrating spheres.6.1.3 The spectral parameters, including the spectral regio
19、n,wavelength measurement interval, and spectral bandwidth.These must be specified since the various VDU technologiesmay demand more or less stringent requirements.6.1.4 The type of standard used to calibrate the system, astandard lamp, a calibrated source, or a calibrated detector, andthe source of
20、the calibration.6.1.5 The physical and temporal characteristics of the VDUincluding, refresh or field rate, convergence and purity adjust-ments (if the manufacturer allows such), luminance level, andany spectral line character in the emission from the VDU. Theintegration time of the detector system
21、should be noted inrelation to the refresh or field rate of the VDU. (See IEC No.441.)7. Apparatus7.1 The basic instrument requirement is a spectroradiomet-ric system designed for the measurement of spectral radianceor irradiance of light sources. See Practice E 1341 for detailson each of the parts o
22、f a spectroradiometer and how to calibrateand use the instrument.7.2 Calibration Sources:7.2.1 The standard calibration source for spectroradiometryis a tungsten-filament lamp operated at a specified current. It ispreferable to have more than one standard lamp to permitcross-checks and to allow cali
23、bration at a range of luminancelevels.7.2.2 Monochromatic emission sources such as a low-pressure mercury arc lamp or tunable laser should also beavailable for use in calibrating the wavelength scale.7.2.3 The electrical supplies for the calibration sourcesshould be of the constant current type. The
24、 supply should belinear and not a switching supply. Current regulation should bemaintained to better than 0.1 %. At this level the radiant fluxfrom the calibration source is at least an order of magnitudemore stable than the flux from a VDU.7.2.4 There should be a standard for length measurementsava
25、ilable (such as a high quality metric rule) since absoluteirradiance calibration must be performed at an exact distancefrom the filament of the calibration lamp.7.3 Receiving OpticsTo maximize the light throughputthe number of optical surfaces between the source of lightshould be kept to a minimum.
26、In extended diffuse sources(such as VDUs) only a set of limiting apertures will be needed.In some instances, it may be desirable to image the VDU withan intermediate focusing lens or mirror assembly. Care shouldbe taken to use a magnification that will adequately fill theentrance slit when viewing b
27、oth the calibration and test source.8. Calibration and Verification8.1 Calibration and its verification are essential steps inensuring that precise and accurate results are obtained byspectroradiometric measurements. They require the use ofphysical standards, some of which may not be normallysupplie
28、d by commercial instrument manufacturers. It remainsthe users responsibility to obtain and use the physical stan-dards necessary to keep his instrument in optimum workingcondition.8.2 Radiometric Scale:8.2.1 Zero Calibration or Its VerificationAll photometricdevices have some inherent photocurrent,
29、even in the absenceof light. This so called “dark current” must be measured andsubtracted from all subsequent readings either electrically orcomputationally.8.2.2 Radiometric Scale Calibration A physical standardof spectral irradiance is normally used for calibration. After thedark current has been
30、measured, the calibration source ispositioned in front of the receiving optics at the specifieddistance and operated at the specified electric current. Thisprovides a good approximation to a Plankian radiator acrossthe visible spectrum. The calibration source is measured andthe values of the dark-cu
31、rrent-corrected photocurrent are re-corded. These photocurrents are then related to the calibrationvalues of spectral irradiance that were provided by the stan-dardizing laboratory. The ratio of spectral irradiance to photo-current becomes the instrument calibration factor. All subse-quent measureme
32、nts are multiplied by this ratio.8.2.3 Linearity VerificationPeriodically after the radio-metric and zero scale readings are established, the linearity ofthe scale should be verified.8.2.4 All calibrations should be performed using the sameintegration time constant that will be used during the measu
33、re-ment of the VDU.8.3 Wavelength Scale:8.3.1 Scale Calibration and Verification Since the outputof a cathode ray tube (CRT) type VDU contains some linestructure, the wavelength scale must be precise and accurateenough to characterize this line structure. Generally, the bestmethod of calibration or
34、verification of the wavelength scale isto determine the difference between the measured peaks, ormore preferably the wavelength centroids, and the tabulatedpositions of the emission line of mercury or neon arc lamps.Most monochromators exhibit significant nonlinear errors inE 1336 96 (2003)2addition
35、 to the random linear errors. Generally, the best methodof either calibration or verification of the wavelength scale is todetermine the differences between the measured peaks and thetabulated positions of the emission lines of the arc lamps. Thedifferences should be averaged and reported. Random er
36、rorslarger than 1.0 nm should be cause for concern.9. Procedure9.1 Selection of Measurement Parameters:9.1.1 If the VDU is small or highly directional so that thesolid angle subtended by the instrument aperture is a largefraction of the VDU area then measure the spectral irradiance.If the VDU is lar
37、ge, then measure the spectral radiance. Utilizethe appropriate calibration source. Mount all pieces of theapparatus solidly in place. An optical table or bench is highlyrecommended.9.1.2 Select the spectral region, measurement interval, inte-gration time constant and the spectral bandwidth (if possi
38、ble).Try to keep the spectral bandwidth and measurement intervalequal. The bandwidth should be no greater than 5.0 nm. ForVDUs with narrow band emitters, such as the P22 red CRTphosphor, the spectral bandwidth should be less than 2.0 nm.(See IEC No. 441.) The default spectral region should be 380to
39、780 nm. This region may vary slightly depending on thetechnology of the VDU being characterized. It is unnecessaryto scan a VDU in a spectral region where there is no radiantoutput but the actual extent of region should be determinedexperimentally.9.1.3 Place the calibration source at the specified
40、distancefrom the monochromator entrance aperture. Measure the VDUat the identical distance from the monochromator entranceaperture.9.2 Selection of Computational Parameters:9.2.1 Depending on the geometry of the measurements,select either radiance or irradiance calculations. Determine ifcorrelated c
41、olor temperature calculations are required and usethe correct CIE chromaticity coordinates and formulae for thecalculations, the 1960 uniform chromaticity scales and the1931 CIE color matching functions are the correct choices.5Use Km= 683 lm/W for the maximum spectral luminousefficacy. Note that ne
42、ither luminance nor color temperature aredefined in terms of the 1964 CIE Supplementary StandardObserver.9.2.2 Practice E 308 indicates that CIE tristimulus valuesare to be normalized by a constant that is calculated for theilluminant-observer pair. Here, the VDU is both the object andthe source of
43、light. To calculate CIE absolute tristimulusvalues, multiply each spectroradiometric reading (in Watts) bythe value of a CIE 1931 color matching function ( x, y,orz) forthat wavelength. Sum these products over all wavelengths foreach of the color matching functions. (See CIE No. 15.2.)Multiply the s
44、um by Km, the maximum spectral luminousefficacy, which equals 683 lm/W.9.3 Measurements:9.3.1 Determine the zero scale first. This can be done eitherby scanning the spectral region with the entrance slit blockedand subtracting the reading from subsequent scans, or bymanually adjusting the radiometer
45、 to read zero when theentrance slit is blocked.9.3.2 Scan the calibration source and determine the sys-tems spectral calibration factor by ratioing the tabulatedspectral radiance (irradiance) values to the measured photocur-rent.9.3.3 Replace the calibration source with the VDU and scanthe test sour
46、ce using the same settings. Multiple the readingsby the spectral calibration factor, wavelength by wavelength.9.3.4 For many radiometric measurements, the unknownphase relationship between the integration period of the spec-troradiometer and the field refresh rate of the VDU dominatesthe measurement
47、 error. Two alternative measurement tech-niques are suggested. First one could synchronize the radiom-eter integration time interval with the VDU refresh cycle andthen integrate for an integral number of refresh cycles. Second,one can integrate for a large number of refresh cycles thatexceed the inv
48、erse of the precision desired in the measurement.10. Report10.1 The report of the color measurement of a VDU shallcontain the following:10.1.1 Identification of the type of VDU (CRT, EL, LCD,etc.).10.1.2 Date of measurement.10.1.3 Orientation of the VDU relative to the spectroradi-ometer.10.1.3.1 Th
49、is should include the relationship in spatial andtemporal parameters between the VDU and spectroradiometer.Field rate and integration time constant, distance between theentrance aperture and the source, surface properties such asmicrostructure (dot triad geometry), convergence and purity (ifappropriate), and setting of brightness and contrast controls.10.1.4 Size of the measured area, in linear dimensions.10.1.4.1 All dimensions shall be reported in SI units (me-tres).10.1.5 The spectral region, spectral bandwidth, and mea-surement interval.10.1.5.1 All wavelength related pa
