A Study of Mold Grinding and Pressing Conditions in the Molding of Aspheric Glass Lenses for Camera Phone Module

Abstract

This study investigated the following two issues using the design of experiment (DOE): (1) grinding conditions of tungsten carbide (WC) mold to fabricate aspheric glass lenses for the megapixel camera phone module and (2) pressing conditions in the molding process using the mold fabricated under the optimum conditions found by DOE. The optimization of the grinding and the pressing conditions with respect to the surface roughness (Ra) of the ground WC and the form accuracy (PV) of the molded lens, respectively, were ascertained by employing factorial design method. As a result of the analysis of variance (ANOVA) and P-value (significance level), it was verified that the depth of cut in the grinding process and, in case of the pressing, the time of pressing step 2 represent the most significant operative variables that affect the corresponding response variable. The WC mold was fabricated under the optimum condition found by DOE and it shows a PV of 0.181 µm in aspheric surface. In the optimum condition, percentage transcription ratio is supposed to be 82%.

Keywords:

• Analysis of variance (ANOVA)
• Aspheric glass lens
• Camera phone module
• Depth of cut
• Design of experiment (DOE)
• Factorial design
• Feed rate
• Form accuracy (PV)
• Glass molding press (GMP)
• Optical fabrication
• Precision optics
• Surface roughness (Ra)
• Transcription ratio
• Tungsten carbide (WC)
• Ultra-precision grinding

Notes

∗SC: Slow cooling.