| 摘要 |
PURPOSE: To uniformize the photoreceptor layer by controlling the aluminum concn. in an anodizing soln. within an appropriate range. CONSTITUTION: When a sulfuric acid process is used as the anodization method, the sulfuric acid concn. is controlled to 150-250g/l, preferably 170-190g/l, the dissolved aluminum concn. to <=10g/l, preferably 4-6g/l, and the deflection of the concn. within 0.5g/l more preferably within±0.25g/l. The aluminum concn. is controlled mainly by dilution. In this case, the aluminum concn. is lowered by purging a specified amt. of the anodizing soln. contg. aluminum and admixing aq. sulfuric acid having an appropriate concn. and free of aluminum by the volume corresponding to the purged soln. Consequently, the aluminum concn. of the soln. is controlled within a specified range.
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