Naraji Sakamoto

Acoustic diaphragm for speakers and method of producing the same

An acoustic diaphragm for speakers having a sandwich structure constituted by a core material comprising an elongated web material bent to have a plurality of radial projections, and upper and lower surface members adhered to the upper and lower edges of the core member, as well as a method of producing the same. The acoustic diaphragm of the invention has a reduced weight while exhibiting a large flexural rigidity so that the nodal line during the resonance vibration can have a circular form which in turn offers a circular form of nodal line and increased speaker power. Also, the method of producing the invention permits easy fabrication of the acoustic diaphragm having a sandwich structure.

The solid boriding of permalloy for magnetic head application

Abstract The solid bonding of Permalloy with a powder mixture of boron carbide and accelerators was studied for magnetic head application. Heat treatments were carried out in the temperature range 800 – 1050 °C in a muffle furnace. The effects of temperature, heating period, atmosphere and the content of bonding accelerators, such as Na 2 CO 3 and Na 2 B 4 O 7 , on the thickness of the boride layer were investigated by using microscopic examination and X-ray microanalysis. At the optimum condition, a boride layer over 200 μm thick was formed within several hours through treatment at 1000 °C in an H 2 atmosphere. The main composition of the boride layer formed on the Permalloy was Ni 2 B and the microhardness Hv was 800 – 1000 (with a 100 g load). It was found that the wear resistance of the boronized Permalloy thus formed was approximately six times greater than that of regular Permalloy.

The growth of boron films by physical vapour deposition

Abstract In spite of the fact that the growth of boron films has always been very difficult because of the high melting point of boron, we investigated the growth of thin films of boron. The boron films were prepared on a titanium substrate by an ion plating method. The morphology of films grown by this method was studied. From electron microscope studies it was shown that the properties of the films depend on the deposition rate and the substrate temperature.

Binaural earphone for out‐of‐head localization

This paper describes a binaural sound reproduction system which converts a monaural electric signal to a sound wave by an electroacoustic transducer and transmits the converted sound wave through acoustic transmission paths such as tubes to the left and the right ears of listener. This system has a reverberation unit comprising a pure mechanoacoustic element which produces two indirect sounds. These indirect sounds have a time delay relative to the direct sound and a phase difference of 180° from each other, and are mixed with the direct sound for each ear. These mixed sounds are transmitted through the acoustic transmission paths to the left and the right ears so that a sound image is localized externally of the head of the listener. As mentioned above, this paper presents the construction of the binaural earphone for out‐of‐head localization.