Patent ID: 7728856

Claim:
A light amount correcting method for a light emitting apparatus having a plurality of light emitting devices including a first light emitting device and a second light emitting device, and some of the plurality of light emitting devices being arranged between the first light emitting device and the second light emitting device, the method comprising the steps of: measuring light amount values of a plurality of the light emitting devices; extracting high frequency components from the measured light amount values; extracting low frequency components from the measured light amount values; calculating a first correction value for correcting a light amount value of the first light emitting device on the basis of the high frequency components; calculating a second correction value for correcting the light amount value of the first light emitting device on the basis of the low frequency components values, wherein the light amount value of the first light emitting device is corrected based on the first correction value and the second correction value such that the light amount value of the first light emitting device is included in both of a first allowable range and a second allowable range, and wherein the first allowable range is between an upper limit of the high frequency components and a lower limit of the high frequency components, and the second range is between an upper limit of the low frequency components and a lower limit of the low frequency components; and correcting a light amount value of the second light emitting device such that it is included in both of the first allowable range and the second allowable range, wherein at least one of the lower limits of the first and second allowable ranges is set to a value that includes a value corresponding to a deterioration of the light amount values according to an elapsing time of the light emitting devices.