Yoshinobu Ishida

An Experimental Home-use Digital VCR With Three Dimensional DCT And Superimposed Error Correction Coding

An experimental digital VCR system for home use is described. A high-quality moving picture is obtained by a newly developed bit rate reduction technology, which is based on subband and three-dimensional DCT (discrete cosine transform) coding. A high-density magnetic recording method which adopts a 12-to-15 modulation scheme and superimposed error correction coding enable sufficient recording time with a small cassette. Component video signals with a ration of 4:2:2 were compressed to about the ratio of 1/7, keeping a high quality, using the subband and 3-D-DCT coding method. >

Optical pick-up for DVD

The optical pick-up for DVD with CD compatibility is discussed. DVD players or DVD-ROM drives are strongly required to have the conpatibility with conventional CD for the comrcialization of DVD. However, the difference of the substrate thickness between DVD and CD causes the different spherical aberration and prevents the laser beam from being focused into a diffraction limt spot size with only one objective lens. Several types of optical pick-ups for overcoming this problg and the twin lens type optical pick-up which is one of these solutions, are introduced.

On the development of mini disc players

A very thin portable MD (mini disc) and a four-disc MD auto changer for cars have been developed. The development of a very small optical pickup and small mechanisms in particular, together with the small MD discs, has helped to dramatically reduce the size of portable MDs and the construct a four-disc MD auto changer system of only 1 DIN size. In the auto changer, by developing a new memory control, four discs can be played continuously. It has been confirmed that vibration characteristics of the MD changer are no longer a practical problem. >