METHOD AND APPARATUS FOR MEASURING FORWARD VOLTAGE DROP OF LIGHT-EMITTING DEVICE, SYSTEM OF LIGHT SOURCE AND THERMAL PRINTER USING THE SAME

摘要

PROBLEM TO BE SOLVED: To measure a forward voltage drop of a light emitting device with a simple structure.

SOLUTION: An optical fixing device 16 comprises a light emitting device array that includes a plurality of device columns L in which a plurality of LEDs 21 are connected in series. Transistors Tr1 to TrN are connected to each device column L1 to Ln to energize each of them. A capacitor 50 is connected to each of the device columns L1 to Ln in parallel. After a switch Sb is turned on to charge the capacitor 50; each of the device columns L1 to Ln is selectively energized, and then the charge of the capacitor 50 is discharged through the energized device column. The forward voltage drop VFL of each device column is measured based on the voltage of the capacitor 50 of which charge has been discharged.

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