Emerging magnetic technologies for consumer audio/video (invited)

Abstract

In the field of consumer audio/video, digital technology is the natural path for advancement. In audio systems, it has just been introduced in the form of digital compact cassette tape recorder and mini disk system in which magneto-optical recording is used. Therefore, the digital video instruments, such as small cassette digital video tape recorders (VTR) for high-definition television and static or short moving image devices will be the next attractive goals to be achieved. Technology analysis shows that the basic techniques of signal processing for small cassette VTR, in which the recording density of 1 μm2/bit and the data rate of 130–160 Mb/s are required, are almost at hand. For the media, improved metal-evaporated tape including oblique incident Co-CoO will be the most favorable candidate, although particulate media of metal powder tape (including Co or N modified forms) or Ba-ferrite tape coated by using the newly developed ultrathin coating techniques may take its position with the help of enhanced head sensitivity, because of their better durability. The basic demand for increasing saturation induction Bs of the head materials will be fulfilled by fine grain Fe-based materials, the available Bs being as high as 2 T. A dramatic increase in magnetoresistive (MR) head sensitivity is expected by using the giant MR effect, although a breakthrough is required to extract its full potential. On the other hand, varieties of static (including short moving) image devices will be developed by use of rapidly progressing magneto-optical recording technology. Preliminary techniques are now ready to meet the demand for the required increase in bit rate and recording density. A bit rate of 64 Mbits/s (8 Mbytes/s) has already been attained. A bit density of 107 bits/mm2 (6.5 Gb/in.2) is likely to be realized, and a factor of 2 or 3 more enhancement can be counted on. Rigid disk and perpendicular recording will have a chance to participate in the field if their techniques are applied to removable media.