No.2（2007）9.Development of a measuring system of the photometry of LED modules

Toshihide Iwanaga, Tetsuo Yamamoto, Hirotaka Nakamura

We have developed the measuring system of the photometric quantities (illuminance, luminous intensity distribution and total luminous flux) of LED modules for lighting. This system is mainly composed at the photometer-bench, the light source mounting unit and the photometer unit. The photometric quantities can be measured automatically using the control system of the motorized linear stages (0.6-5 m) and the rotation stages (+/-120 degrees from the vertical, +/-180 degrees of horizontal-angle). The color correction factor can be measured by combining the spectrophotometer with the photometer when measuring colored LEDs.

We have developed a method that reduces the angle error when setting up an LED module. As a result, the photometric precision was improved by this system. Also, the appropriate measured distances have been obtained by verifying the error from the inverse-square law which causes large errors when measuring luminous intensity.

The uncertainty of the illuminance measurement was estimated across the system. As a result, the combined standard uncertainty was about 2% to the LED module with strong directivity and was about 1% to the LED module with weak directivity. Therefore, sufficient measurement reliability has been obtained across the system.

Keywords

luminous intensity, luminous intensity distribution, total luminous flux

Back to Contents