Method for predicting lifetime of photo-semiconductor device and drive apparatus
AssigneeNichia Corporation
InventorTsuyoshi Ohgoh
Life of this patent
Estimating the term…
Abstract
In a method for predicting the lifetime of a photo-semiconductor device that has a maximum light output value restricted by thermal saturation, the maximum light output value is extracted by measuring the characteristic of light output from the photo-semiconductor device with respect to drive current. The decrease tendency of the maximum output values with respect to drive time is predicted to predict the lifetime of the photo-semiconductor. Further, the predicted lifetime is updated as time passes. Therefore, in this method, even if drive condition changes, or an individual difference of the photo-semiconductor per se is present, it is possible to substantially accurately predict the lifetime of the photo-semiconductor.
Claims10
A method for predicting, based on the degradation tendency of a photo-semiconductor device, the lifetime of the photo-semiconductor device that outputs light at light output values including a maximum light output value that is restricted by thermal saturation, the method comprising using one or more processors to perform the steps of:
- extracting the maximum light output value of the photo-semiconductor device by measuring the characteristic of light output from the photo-semiconductor device with respect to drive current;
- repeating the step of extracting the maximum light output value of the photo-semiconductor device at least once, thereby extracting a plurality of maximum light output values of the photo-semiconductor device at a plurality of extraction points in total;
- calculating a degradation curve that approximates the characteristic of the maximum light output values with respect to drive time periods that have passed after initially driving the photo-semiconductor device;
- calculating, based on the degradation curve, a drive time period at which the maximum light output value on the degradation curve and a drive light output value that is set in a drive apparatus of the photo-semiconductor device become the same;
- and
- predicting that the calculated drive time period is the lifetime of the photo-semiconductor device.
Dependencies are inferred from the claim text.