1、Designation: E1336 11Standard Test Method forObtaining Colorimetric Data From a Visual Display Unit bySpectroradiometry1This standard is issued under the fixed designation E1336; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe fundamental procedure for characterizing the color and luminance of a visual display unit(VDU) is to obtai
3、n 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 precisioncolorimetric data for th
4、is purpose are contained in this test method. The values and procedures forcomputing CIE chromaticity coordinates are contained in Practice E308. The procedures for obtainingspectroradiometric data are contained in Test Method E1341. This test method includes somemodifications to the procedures give
5、n in Practice E308 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 displays (ELD).1. Scope1.1 Th
6、is 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 asstandard. No other units of mea
7、surement are included in thisstandard.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 li
8、mitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E284 Terminology of AppearanceE308 Practice for Computing the Colors of Objects byUsing the CIE SystemE1341 Practice for Obtaining Spectroradiometric Data fromRadiant Sources for Colorimetry2.2 CIE Publications:Publication CIE No. 18
9、Principles of Light Measurements3Publication 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 Scree
10、n, 197443. Terminology3.1 The definitions of appearance terms in TerminologyE284 are applicable to this test method.1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.06 on ImageBased Color Measurement.Current
11、 edition approved Nov. 1, 2011. Published November 2011. Originallyapproved in 1991. Last previous edition approved in 2003 as E1336 96 (2003).DOI: 10.1520/E1336-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Bo
12、ok of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from U.S. National Committee of the CIE (International Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01970, http:/www.cie-usnc.o
13、rg.4Available from International Electrotechnical Commission (IEC), 3 rue deVaremb, Case postale 131, CH-1211, Geneva 20, Switzerland, http:/www.iec.ch.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method4.1 Proc
14、edures are given for obtaining spectroradiometricdata and for the calculation of CIE tristimulus values and othercolor coordinates to describe the colors of VDUs. Modifica-tions to the standard calculation procedures of Practice E308are described.5. Significance and Use5.1 The most fundamental metho
15、d for obtaining CIE tris-timulus values or other color coordinates for describing thecolors of visual display units (VDUs) is by the use ofspectroradiometric data. (See CIE No. 18 and 63.) These dataare used by summation together with numerical values repre-senting the 1931 CIE Standard Observer and
16、 normalized to 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 E308are given to correct for the unusual nature of narrow ordis
17、continuous sources.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
18、 as illuminance (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
19、 from the VDU, 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 s
20、pectral region,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, andt
21、he source of 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 det
22、ector system 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 E1341 for details oneach of
23、 the parts of 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 t
24、o allow calibration 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 curre
25、nt type. The 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 mea
26、surementsavailable (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
27、 a minimum. 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 wh
28、en viewing both 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 nor
29、mallysupplied 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 ph
30、otocurrent, 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 curren
31、t has been 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
32、the dark-current-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-quen
33、t measurements 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.E1336 1128.2.4 All calibrations should be performed using the sameintegration time constant that will be u
34、sed during the measure-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 bestmetho
35、d of calibration or 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 inaddit
36、ion 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
37、 errorslarger 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
38、large, 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 po
39、ssible).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 380
40、to 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 specifi
41、ed 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 ifcorrelate
42、d color 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
43、 neither luminance nor color temperature aredefined in terms of the 1964 CIE Supplementary StandardObserver.9.2.2 Practice E308 indicates that CIE tristimulus values areto be normalized by a constant that is calculated for theilluminant-observer pair. Here, the VDU is both the object andthe source o
44、f 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
45、 sum 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 radiomet
46、er 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 so
47、urce 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 measureme
48、nt 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 i
49、nverse 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 This 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), converge
