Takehisa Yoshikawa

Ultra-Precision Cutting of Roll Die with Micro Lens Arrays for Plastic Film

Patterning vast numbers of micro lenses on a surface increases technical importance to improve characteristics of optical parts such as liquid crystal displays. A cutting method using a diamond tool is examined to make a molding die by which array patterns of many micro lenses are molded. Realizing the cutting procedure, the developed machining system employs a cutting unit actuated by PZT and a synchronous control system of the cutting unit with a NC controller. The present paper investigates machining of micro lenses on the order of 2 kHz, using a piezo-actuated micro cutting unit. Experiments using this unit revealed that it is possible to machine a large number of micro lenses on a molding roll die for plastic film with high precision.

Advanced Diamond Charging Process Using Vibrating Charging Ring in Fixed Abrasive Lapping

In the lapping of magnetic heads and other electronic components composed of multiple materials, differences in the processing characteristics of the composite materials produce residual steps on the surface at composite interfaces. Residual step heights have been reduced to as small as a few nanometers. We investigated using fine abrasives in fixed abrasive lapping to further reduce the residual step height. This requires highly secure, high-density embedding of abrasives on the lapping plate. To this end, we evaluated the surface morphology of the lapping plate after diamond abrasive charging and investigated the embedding mechanism of diamond abrasive charging. The results obtained will assist in determining the direction of future research and development. A prototype charging ring that uses a vibrating system was developed to increase the density of abrasives embedded on the lapping plate. This diamond charging using a vibrating system was able to increase the embedded abrasive density and improve the flatness of the charging plate.

Mechanical Characterization of Lapping Plate Materials in Diamond Charging Process

In the lapping of magnetic heads and other electronic components composed of multiple materials, differences in the processing characteristics of the composite materials result in “residual steps” forming on the surface at composite interfaces. Residual step heights have been reduced to as little as a few nanometers. We investigated using fine abrasives in fixed abrasive lapping for this purpose, which requires highly secure, high-density embedding of the abrasives on the lapping plate. To this end, we modeled the abrasive embedding process and investigated the relationship between the mechanical properties of the lapping plate and the retention of the abrasive, to determine the direction of further research and development. The results of this investigation revealed a correlation between the work hardening in the plate and the resulting abrasive density and cutting edge height. The investigation also showed that it is possible to suppress the reduction in lapping rate that occurs during use by increasing the work hardening coefficient of the plate.

Ultra-Precision Machining of Dies for Microlens Arrays Using a Diamond Cutting Tool

Patterning of numerous microlenses on a surface improves the optical performance of components such as liquid crystal displays. A cutting method using a diamond tool is examined to fabricate a molding die that employs arbitrary array patterns to mold millions of microlenses. The present paper investigates machining of microlenses on the order of 2 kHz, using a piezo-actuated micro cutting unit and a synchronous control system of the cutting unit with an NC controller. Experiments using this system revealed that it is possible to machine a large number of microlenses on a molding die with high precision.