Isao Yasuda

Newly developed sendust video head for high coercive tape

The effective permeability (μ eff ) and the loss factor ( \tan\delta/\mu_{eff} ) of the sendust alloy in extremely thin condition were measured at the video frequency region. Results show that around the thickness of 15 μm, the effective permeability and the loss factor of the sendust alloy become comparable to those of Mn-Zn single crystal ferrite at high frequency region(>5MHz). A narrow track sendust video head was developed, for the first time, and its output properties were measured for both a high coercive tape(metal tape) and a conventional tape(CrO 2 tape). It was found that the output signal of the sendust head for the metal tape was 5 ∼ 6dB larger than for the CrO 2 tape at 0.5 ∼ 4MHz, and reached 6 ∼ 10dB larger at 5 ∼ 7MHz.

Ultra-high density recording with sendust video head and high coercive tape

The recording and the reproducing efficiencies of the advanced sendust video head and a ferrite video head for tapes with coercivities of 700-1700 Oe were examined. It was observed that the recording efficiency of the sendust head is superior to that of the ferrite one, especially for high coercive tape, while the reproducing efficiencies of both heads are comparable. Data is shown which demonstrates the ability of the sendust video head to record on tapes with coercivities up to 1700 Oe without core saturation. Using the sendust head with an extremely narrow gaplength (0.2μm), sine-wave signals of short wavelength (smaller than 0.43μm) were recorded on high coercivity (1450-1700 Oe) tapes and reproduced successfully.

Magnetic head incorporating a glass composition of barium oxide and phosphorous pentaoxide

A magnetic head comprises a main core (1) made of sendust material or amorphous alloy and a pair of reinforcing cores (5,5) for holding the main core so that the main core is sandwiched between the pair of reinforcing cores. The main core (1) is comprised of a pair of core halves (1a, 1b), the pair of core halves being adhered to each other by glass material containing phosphorus pentaoxide (P2 O5) and barium oxide (BaO) as main constituent elements. P2 O5 is about 40% of the whole glass material and BaO is about 50% wt. of the whole glass material.

Double Track Video Heads for Magnetic Disk

The crosstalk, electromagnetic conversion, and service life characteristics of two-channel gap inline heads with Sendust bulk head structures (track width 60 ¿m, gap 0.2 ¿m) are discussed. When the mutual inductance between heads M is small, crosstalk occurs during reproduction but not during recording. By reducing the core size, M was reduced, lowering the crosstalk level during reproduction. Studies of the gap depth dependence of the reproduction output indicated that reducing the gap depth by 20 ¿m would only result in an output increase of 3 dB, but would have adverse effects on the head life and reliability due to friction.