1TES O*

153

HU.S.

RTMENT

OF

IMMERCE

National

Bureau

of

standards

^'sriirsrNBS technical note

OCT 6 198)

191119

QC

/OO

821
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress March 3. 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (I) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology,

the Institute for Computer Sciences and Technology, and the Office for Information Programs.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United

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divisions: Computer Services — Systems and Software — Computer Systems Engineering — Information Technology.

THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and

accessibility of scientific information generated within NBS and other agencies of the Federal Government; promotes the development of the National Standard Reference Data System and

a system of information analysis centers dealing with the broader aspects of the National Measurement System; provides appropriate services to ensure that the NBS staff has optimum

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* Part of the Center for Building Technology.
Photometric Data Variability

of Automotive Lighting Components

National Bureau of Standards

Bert G. Sirason

National Highway Traffic Safety Administration

Department of Transportation

Washington, D.C. 20590

and

John Mandel

Institute for Materials Research

National Bureau of Standards

Washington, D.C. 20234

£

U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

Issued March 1974
National Bureau of Standards Technical Note 821

Nat. Bur. Stand. (U.S.), Tech. Note 821, 15 pages (Mar. 1974) CODEN: NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1974

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. C13.46:821). Price 60 cents.
Photometric Data Variability of

Automotive Lighting Components

Bert G .- Simson and John Mandel

were

1 abo

phot

duci

phot

by F No.

meth

10 p

Howe

more

tion

Four au tested

r a t o r i e s ometri c bi 1 i ty

.

ometri c ederal M

108. Th

od was p ercent c

v e r , t h i as an i s than a

tomoti

in t h

r

to es

data r The 1 t e s t i n otor V

e prec

1 aced

oef f i c

s valu

n d i c a t

s a pr

v e 1 i g h t i ee commer

t i m a t e t h e p e a t a b i 1 aboratori

g t e c h n i q e h i c 1 e S a

i s i o n of

in a rang

ient of v e shoul

d

ion of ex

e d i c t i v e

ng compo

cial tes

e degree

i ty and

es used

ues requ

fety Sta

this tes

e of abo

a r i a t i o n be c o n s

i

i s t i n g c paramete

nents

ting

of

repro

the

ired

ndard

tut

dered

o n d i - r

.

Key words: Federal Motor Vehicles Safety

Standards; i nterl aboratory test evaluation;

motor vehicles; photometric testing;

safety standards.

I . Introduction

ments

stop

R e q u i v a r i o This

e s t i m

i d e n t

the r

c o n s i light

v i o u s p 1 i a n [2].

FMVSS N for au lights,

rements

us mech

paper d

ate the

i c a 1 1 i eproduc

sted of

ing com

ly been

ce test

o. 10

tomot

ref 1 in t

anica

i s c u s degr

g h t i n ibili

two

ponen

sele

ing o

8 [1]

i ve 1 ex re

he st

1 , en

ses a ee of

g com

ty am

p a r k i t man

cted

f the

1 speci

i g h t i n g

f

1

ector

andard

vironme

round

photom

ponents

ong sev

ng and

uf actur

from au Office

f ies

comp

s , se

i n c 1 u ntal

robin

etri c with

eral

two t

ers . tomot

of S

mi mm

onent

aled

de de

and p

expe

data

i n a

1 abor

ail 1 The

i ve a tanda

urn pe

s sue

beam

t a i 1 e hotom

rimen

repe

sing!

a t o r i amps

compo

ssemb

rds E

rformance requireh as tail lamps,

headlights, etc.

d procedures for

etric tests,

t designed to

atability for

e laboratory, and

es. The sample

representing three

nents had prely lines for comnforcement (OSE)

II. Test Procedure

In practice, the photometric tests were conducted as follows: A lighting component, (such as a tail lamp), was

mounted unto a test fixture built to simulate the component's

orientation in its designated vehicle. The original bulb was

1 Figures in brackets indicate the literature references at the

end of this paper.

1
replaced with another bulb calibrated 2 in accordance with

techniques specified in the SAE Lighting Standard [3]. Then,

the fixture with the lamp was mounted on a goniometer with

two angular degrees of freedom. The goniometer could be

indexed ten degrees of arc from the normal in the vertical,

and twenty degrees of arc from the normal in the horizontal

plane. A photoelectric detector, facing the assembly from

100 feet away, and the associated electronic equipment completed the experimental setup.

FMVSS No. 108 [1] requires the measurement of directional luminous intensity (in candlepower) at 27 defined horizontal and vertical angle combinations of the goniometer's

setting. To check for compliance with the minimum requirement

in the standard, the 27 candlepower values are pooled into

seven groups representing aggregates of three to five test

point values. Figure 1, FMVSS No. 108 [1] lists minimum

candlepower values for each group (also called "zone").

I r a t o r i eral ly

than s it was

ments . the on type o

v a r i a b

using

design

i brate

s i x t e e in e a

c

to 1 ab

n this e es under

a d v i s a b

i x , and

i m p o s s i Indeed

ly comme

f testin

i 1 i ty , w

di f feren

ated mea

d by eac

n lamp-b

h labora

oratory.

xperime

contra

le to r prefera

b 1 e in

, the t

r c i a 1 i To

teste

rated

spher

1 abor

ulb com

tory, t

nt, we tested four lamps in three laboct with the OSE [2]. While it is genun i nterl aboratory studies on no less

bly fifteen or more laboratories [4],

this case to conform to these requirehree participating laboratories are

nstitutions in the U.S. engaged in this

provide data for the within laboratory

d each lamp four times in each laboratory,

bulbs. The bulbs were operated at the

ical candlepower [3], and they were calatory in an integrating sphere. The

binations were tested in a random order

he order being different from laboratory

III. Statistical Analysis of Data

The data were first arranged in a two-way table, (Table

1), in which the rows represented the. 12 laboratory and bulb

combinations (3 laboratories x 4 bulbs), and the columns

represented the 28 lamp and zone combinations (4 lamps x

7 zones). An analysis of this table of data snowed no significant systematic differences between the four bulbs used in

the experiment. Therefore, the four results obtained by each

laboratory for a particular zone on a given lamp, using the

four bulbs, were treated as replicate measurements. The

statistical analysis then proceeded to the calculation of the

repeatability and reproducibility [4] of the test method.

Preceding the first calibration, the bulbs were seasoned for

1% of their rated average lifetime to assure stability.

2
The standard deviation of repeatability, s r

, is a measure

of the variability obtained when the same laboratory measures

repeatedly the same zone of the same lamp, using, however, a different bulb for each replicate measurement.

The standard deviation of reproducibility, sr, is a measure of the variability obtained between single measurements

made in different laboratories on the same zone of the same

lamp. The estimate, sr, is obtained by the formula

2

R = V

+ s where s^ is the square of the

2

standard deviation of repeatability defined above, and s^/ is the component of variance due to systematic differences between laboratories .

Ta

value o

d e v i a t i in unit

sr vary

t i o n of

m a g n i t u f 1 c i e n t

the sta

b i 1 i ty

.

coef f i c

t i o n s .

ble 2 lists, for each zone of each lamp, the average

ver all laboratories and bulbs, as well as the standard

on for repeatability and reproducibility, all expressed

s of candlepower. It should be noted that both s r and

between lamps and between zones, and a closer examinathe data reveals that both s r and sr increase as the

de of the measured value increases. Thus, the coefof variation will be a less variable quantity than

ndard deviation for both repeatability and reproduciTable 3 is analogous to Table 2, but lists the percent

ients of variation (%CV) instead of the standard deviaIV. Conclusion

The

and repr

observed

d u c i b i 1 i based on

should b

t i o n s t h

the valu

in a ran

informat

lighting

ment by

averag

o d u c i b i in the

ty (v

R

) only K

t

e c o n s i an as p

e s in T

ge of a ion w i

1

equi pm

this me

e coefficients of variation of repeatability

1 i ty are listed in Table 4. It should be

first place that the values relating to reprosuffer from the severe shortcoming of being

hree laboratories. Therefore these values

dered more as an indication of existing condiredictive parameters. This being recognized,

able 4 place the precision of this test method

bout 10 percent coefficient of variation. This

1 undoubtedly be of value to members of the

ent industry who wish to evaluate their equipthod

.
V References

[1] Federal Motor Vehicle Safety Standard No. 108 Lamps,

Reflective Devices and Associated Equipment-Passenger

cars, Multipurpose Passenger Vehicles, Trucks, Buses,

Trailers and motorcycles (Docket No. 69-18). 35 F.R.

16842, Octover 31, 1970; 37 F.R. 21328, October 7, 1972;

37 F.R. 25235, November 29, 1972.

[2] Office of Standards Enforcement, Motor Vehicle Programs,

National Highway Traffic Safety Administration, U.S.

Department of Transportation.

[3] Society of Automotive Engineers

August, 1970.

(SAE) No. J575e,

[4] Repeatability and Reproducibility, A simple analysis

providing excellent parameters. Materials Research

and Standards, Vol. 11, No. 8, pp. 8-16, 1971.
TABLE 1

DIRECTIONAL LUMINOUS INTENSITY - CANDLEPOWER

LAMP NO. 1

Lab. Bulb Z-l Z-2 Z-3 Z-4 Z-5 Z-6 Z-7

1 60.0 68.0 71.0 121.0 47.

C

31.2 33.8

2 51.9 67.0 71.0 133.0 53.0 33.0] 39.7

3 54.9 66.0 75.0 138.0 52.0 34.0 36.9

4 56.6 63.0 70.0 122.0 48.0 31.8 33.4

1 59.0 74.2 75.5 139.6 57.0 34.7 43.1

2 52.1 71.5 65.5 131.5 58.4 29.5 42.1

3 56.8 72.8 75.7 143.4 57.5 34.2 41.5

4 56.0 68.1 70.4 127.6 52.2 32.1 36.9

1 53.19 62.50 67.30 118.1 45.70 30.35 32.29

2 49.19 63.30 67.50 121.1 49.10 30.61 37.43

3 51.10 63.70 69.30 127.7 50.10 31.20 36.90

4 59.48 61.80 66.50 117.2 50.10 30.92 38.83
TABLE 1 (continued)

LAMP No. 2

Lab. Bulb Z-l Z-2 Z-3 Z-4 Z-5 Z-6 Z-7

1 1 19.9 19.8 26.5 49.6 27.4 27.8 23.0

2 19.1 20.5 21.7 52.2 33.8 25.9 28.8

3 20.2 20.5 23.8 49'.4 29.8 20.8 22.8

4 19.7 20.3 23.6 46.4 27.1 24.8 22.6

2 1 16.5 17.6 24.7 43.7 21.3 23.1 17.5

2 17.1 15.9 21.7 45.3 27.2 23.1 22.1

3 16.8 17.3 20.2 40.5 24.2 23.8 18.5

4 17.0 18.1 19.1 41.1 2 8.4 23.3 23.1

3 1 18.03 20.22 26.56 48.70 21.84 26.08 18.91

- 2 19.64 20.08 24.73 53.98 31.03 27.15 23.20

3 16.07 20.65 20.06 46.79 27.90 25.95 21.74

4 20.48 18.64 26.56 45.65 23.46 30.32 22.21
TABLE 1 (continued)

LAMP No. 3

Lab, Bulb Z-l Z-2 Z-3 Z-4 Z-5 Z-6 Z-7

1 14.7 9.8 15.9 30.1 15.4 17.3 14.1

2 15.3 9.7 16.6 30.4 15.1 18.1 13.7

3 15.1 9.7 15.6 29.8 15.4 18.2 14.8

4 14.9 9.9 15.3 28.3 14.8 17.1 14.2

1 11.3 10.0 13.7 27.6 14.6 13.1 12,4

2 11.0 9. 8 13.6 28.0 14.7 13.0 11.8

3 10.6 10.0 12.7 27.8 15.6 13.1 13.2

4 11.5 10.0 13.9 27.9 14.7 13.7 12.8

1 12.26 10.73 14.96 29.62 15.29 13.93 12.50

2 12.52 10.3 2 15.40 29.97 15.07 13.79 12.41

3 12.17 10.93 14.36 29.91 16.26 14.47 13.73

4 11.94 10.53 14.27 28.71 15.24 14.19 13.45
TABLE 1 (continued)

LAMP No. 4

Lab. Bulb Z-l Z-2 Z-3 Z-4 SjJS Z-6 Z-7

1 1

2

3

4

2 1

2

3

4

3 1

2

3

4

66.1 35.3 105.0 182.0

61.8 31.9 103.0 192.0

62.5 33.1 110.0 197.0

66.2 34.4 106.0 165.0

64.1 36.6 107.0 206.3

57.7 34.5 105.5 218.1

6-3.5 37.8 114.6 221.7

68.1 37.4 109.8 201.1

59.74 35.05 107.6 201.0

62.32 34.95 104.6 183.2

61.81 35.53 111.3 197.6

63.63 38.37 110.0 184.6

59.0 84.0 34.3

66.0 96.0 34.6

61.0 94.0 33.5

54.0 85.0 33.1

69.5 94.8 38.0

76.0 101.5 38.8

73.1 98.3 37.5

69.8 101.1 40.6

63.30 88.00 32.51

58.40 84.20 32.51

60.10 87.40 32.18

58.70 84.20 34.16
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TABLE 4

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v 5.3 8.6 2.4 4.4

r

vD 7.2 11.3 8.5 7.4

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11

form NBS-114A <l-7i> U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

' SHEET

1. PUBLICATION OR REPORT NO. NBS TN-8212. Gov't Accession No.3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Photometric Data Variability of Automotive

Lighting Components

5. Publication Date March 197^

6. Performing Organization Code

7. AUTHOR(S)

Bert G. Simson and John Mandel

8. Performing Organization

10. Project/Task/Work Unit No. 9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

11. Contract/Grant No.

12. Sponsoring Organization Name and Address

Same as No. 9«

13. Type of Report & Period CoveredFinal

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Four automotive lighting components were tested in three commercial

testing laboratories to estimate the degree of photometric data repeatability and reproducibility. The laboratories used the photometric

testing techniques required by Federal Motor Vehicle Safety Standard

No. 108. The precision of this test method was placed in a range of

about 10 percent coefficient of variation. However, this value should

be considered more as an indication of existing conditions than as a predictive parameter.

17. KEY WORDS (Alphabetical order, separated by semicolons)

Federal Motor Vehicles Safety Standards; inter laboratory test evaluation; motor vehicles; photometric testing; safety standards.

18. AVAILABILITY STATEMENT

PH UNLIMITED.

I I FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

15

22. Price 60 cents

USCOMM-DC 66244-P7I

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