 2000 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA

Appnote 47

www.infineon.com/opto • 1-888-Infineon (1-888-463-4636)

OSRAM Opto Semiconductors GmbH & Co. OHG • Regensburg, Germany

www.osram-os.com • +49-941-202-7178

3

May 31, 2000-14

Contrast Measurements

The ability to read a display in direct sunlight used to be deter-

mined by using a series of standard observers and irradiating

the display with one sun. Recent technical studies have estab-

lished contrast criteria permitting laboratory measurements

that verify sunlight readability.

A yellow ISD2351 and a high efficiency green ISD2353 Small

Alphanumeric Display were evaluated for sunlight readability

under a simulated sun with an incident of 4200 fc. These two

displays were tested with both pass-band and neutral density

AR/CP filters. The measurement technique and results follow.

Figure 1. Sunlight readability contrast measurement setup

Contrast Measurement Setup

Contrast measurements require the use of a spot photometer,

which measures the luminance of the surface within a specific

spot size. A Photo Research Spectra Pritchard spot photometer

Model 1980B with a Macro Spectar MS-80 Lens was calibrated

and set to read out in foot Lamberts, fL. The display and filter

were mounted on a micro adjustable X/Y/Z stage. This stage,

the spot photometer, and a 500 W Unimat LX80 light source

were mounted on a optical bench. The light source was ori-

ented 30

° from the normal of the display. See Figure 1.