Abstract: A high frequency compensator configured to compensate high frequency component of a digital audio signal comprising a down sampler configured to perform ½ down-sampling for the digital audio signal. An up sampler is configured to perform double up-sampling for an output signal of the down-sampler. A digital low-pass filter is configured to filter an output signal of the up sampler, and to output the filtered digital audio signal.

Abstract: A high frequency compensator configured to compensate high frequency component of a digital audio signal comprising a down sampler configured to perform ½ down-sampling for the digital audio signal. An up sampler is configured to perform double up-sampling for an output signal of the down-sampler. A digital low-pass filter is configured to filter an output signal of the up sampler, and to output the filtered digital audio signal.

Abstract: A high frequency compensator includes a down sampler configured to perform ½ down-sampling for a compressed and expanded digital audio signal. An up sampler is configured to perform double up-sampling for an output signal of the down-sampler. A digital low-pass filter is configured to filter an output signal of the up sampler. A digital high-pass filter is configured to filter an output signal of the digital low-pass filter. An adder is configured to add an output signal of the digital high-pass filter to the compressed and expanded digital audio signal, and to output a digital audio signal generated by the adding.

Abstract: A process of forming a high-definition pattern by etching is provided. A photosensitive resin layer is formed on a metal substrate material having a center line-average surface roughness Ra of up to 0.10 &mgr;m and a maximum surface roughness Rmax of up to 1.0 &mgr;m to form a resist pattern. Then, the photosensitive resin layer provided on the metal substrate material is exposed to light to form a resist pattern. Finally, etching is carried out to form a pattern on the metal substrate material.

Abstract: A process of forming a high-definition pattern by etching is provided. A photosensitive resin layer is formed on a metal substrate material having a center line-average surface roughness Ra of up to 0.10 &mgr;m and a maximum surface roughness Rmax of up to 1.0 &mgr;m to form a resist pattern. Then, the photosensitive resin layer provided on the metal substrate material is exposed to light to form a resist pattern. Finally, etching is carried out to form a pattern on the metal substrate material.

Abstract: An optical disc apparatus for writing data on an optical disc 11 and/or reading data from the optical disc 11 by performing seek control for moving an optical pickup 15 to a target track on the optical disc 11 and focus servo of the optical pickup 15 according to a detected focus error signal and a first transfer function. This optical disc apparatus is provided with a memory 17a for holding a second transfer function different from the first transfer function, and executes the focus servo according to the first transfer function when the seek control is not performed or executes the focus servo according to the second transfer function when the seek control is performed. It is therefore possible to reduce the gain of a focus servo system without lowering the stability, for elimination of noise generated during the seek control.