Measuring device in pocket format detects precise LED-brightness values in milliseconds

Designers and developers of lamps are often faced with the problem that the standard LED shipping dimensions and configurations of certain series types contain a product group, which can possibly include LEDs with different color and brightness levels. A highly precise sorting always presents a logistical challenge: Even the most modern LED-production is subject to certain deviations through the complex production process. Particularly by LEDs, the deviation is easy to perceive through different color coordinates and brightnesses. In particular if you are dealing with comparing LEDs from different producers, developers often have the difficulty as to how the LED-quality actually corresponds with the brightness and color coordinates in accordance with CIE-standard (x/y-diagram). LEDs also change their color and brightness with increasing temperature. Thus, the normal testing procedure only takes 25 ms after the LED-production so they do not warm up. In order to be able to synchronize this measuring frame of 25 ms exactly with the flash time, normally very extensive and expensive laboratory instruments are required.

The portable, easy to operate and inexpensive spectrometer GL Spectis 1.1 is used here: It can determine brightness values with a current duration of 25 ms and a precision of +/- 4%. A special trig-out-connection emits a signal at a fixed point of time of the measurement, for example, to an external current source so that the LED illuminates exactly during the measuring period. In this way, the user can simulate the measurement conditions that exist by the manufacturer during the production and development test.

In connection with the mobile integrating sphere GL Opti Sphere 48, the new device was designed so that it reliably measures lumen values and all photometric values of not only individual LEDs, but also other small light sources. Moreover, the system simultaneously scales the spectra. Thus, it determines reliable values for color coordinates, CCT and CRI in accordance with the CIE-standard. Through this, the radiant power and luminous flux can be determined quickly.

Different than by normal spectrometers that can only measure individual LEDs, the mini-spectrometer can take measurements for LEDs that are already found on a printed board through the integrating sphere with a diameter of 48 mm. Through this, the influences of electronic construction elements, drivers and current supplies can be determined on the spectral properties of the LEDs to be measured as well as the usage of dimmers and cooling elements.

The proprietary software included in the scope of delivery, GL Spectro Soft, contains a binning tool, which allows for the specification of the binning groups. It is also possible to import the respective binning system from different providers. The software includes binning libraries from Osram, Cree and Philips so that the respective bin number from the LED is automatically determined for the user.

Through its properties, it makes official measuring processes easier for the mini spectrometer and accelerates these. The system is suitable for measurements on lights and complete light installations, which are constructed of multiple LEDs. With this, it is possible to measure the performance of individual LEDs. Through this, the measurement instrument can be used for the binning of LEDs from different manufacturers according to color and brightness. The handy system can be easily transported and can be used immediately on site. Through this, it is particularly suitable for maintenance work on installed lights. Through the plug and play concept, the system automatically recognizes the corresponding accessories and loads the calibration file independently. Finally, the automatic base line correction makes frequent dark current calibration unnecessary.


Visit GL OPTIC at the electronica 2012:
Hall A1, Booth 671