Browse Prior Art Database

Automatic Measurement of Light Emitting Devices

IP.com Disclosure Number: IPCOM000077820D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Eisenstadt, BM: AUTHOR

Abstract

This is a system employing a closed-circuit television camera as the electrooptical sensor, for automatically measuring brightness and cross talk in the manufacture of light-emitting devices. The television camera accommodates measurements for different spatial configurations of diode arrays in final wafer testing and in final module acceptance testing. Automatic processing of the TV video permits rapid measurements of brightness and cross talk from many adjacent light-emitting diodes (LEDs).

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Automatic Measurement of Light Emitting Devices

This is a system employing a closed-circuit television camera as the electrooptical sensor, for automatically measuring brightness and cross talk in the manufacture of light-emitting devices. The television camera accommodates measurements for different spatial configurations of diode arrays in final wafer testing and in final module acceptance testing. Automatic processing of the TV video permits rapid measurements of brightness and cross talk from many adjacent light-emitting diodes (LEDs).

Wafer 2 containing the LED chips is mounted on positioning table 4 adjacent to calibration lamp 6, which defines the standard power or brightness level. Lamp 7 illuminates the wafer through mask 5 and half-silvered mirror 9. The mask provides two vertical arrays of known light levels, which are employed for brightness comparison with that of the LEDs. Photodiode 11 is aligned with the mask and is used as a comparison means, to set the lamp illumination to the desired value from the calibration lamp 6. Photodiode 11 is also employed to monitor the brightness level of the standard during the taking of measurements.

Wafer 2 is aligned with TV camera 8, which employs a diode array as a sensing layer having a spectral response preferably extending from 0.35 to 1.2 micrometers. The output from camera 8 is fed to a TV monitor 10 and an A/D converter 12. In the figure monitor 10 contains three columns of brightened elements; the center...