Sony Corporation

Mitsui Toatsu Chemicals, Incorporated

Kenichi Baba

Norio Saito

Yutaka Soda

Norimasa Yamaya

Nobuhito Koga

Kenji Yazawa

Junichi Fujio

Kozo Tanaka

Sin Hosonuma

Harue Suzuki

A magneto-resistance effect magnetic head in which the MR effects of the two MR thin films of a MR device are balanced for suppressing Barkhausen noise and assuring a stabilized output. Between a lower-layer magnetic shield core and an upper layer magnetic shield core is arranged an MR device, made up of two MR thin films such that a distance d.sub.1 between the lower-layer magnetic shield core and the MR thin film is smaller than a distance d.sub.2 between the upper-layer magnetic shield core and the MR thin film. A film thickness t.sub.1 of the MR thin film towards the lower-layer magnetic shield core is set so as to be thinner than a film thickness t.sub.2 of the MR thin film towards the upper-layer magnetic shield core. Preferably, the relation 0.5&lt;t.sub.1 /t.sub.2 holds. Also, a resistivity .rho..sub.1 of the MR thin film closer to the lower layer magnetic shield core may be larger than a resistivity .rho..sub.2 of the MR thin film. Preferably, the relation .rho..sub.1 /.rho..sub.2 &gt;3 holds.

Magneto-resistance effect magnetic head

Polyimide resin composition

This invention is a polyimide resin composition containing 100 parts by weight of polyimide having recurring units of the following formula: ##STR1## wherein Y is a bond, divalent hydrocarbon radical having from 1 to 10 carbons, hexafluorinated isopropylidene radical, carbonyl radical, thio radical, sulfinyl radical, sulfonyl radical or oxide, and R is a tetravalent radical of aliphatic radical having at least 2 carbons, alicyclic radical, monoaromatic radical, condensed polyaromatic radical, or noncondensed polyaromatic radical wherein aromatic radicals are mutually connected with a bond or a crosslinking function and from 5 to 100 parts by weight of fluororesin. The resin composition can provide molded products which are excellent in high-temperature stability, dimensional stability and mechanical strength and moreover have a low friction coefficient and good wear resistance. Therefore, the composition is useful as the material for electric and electronic devices, precision instrument parts etc. Polyimide of this invention can be prepared from aromatic diamines and tetracarboxylic acid dianydrides. Suitable aromatic diamines are 4,4'-bis(3-aminophenoxy)biphenyl, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3aminophenoxy)phenyl] sulfide etc. Suitable tetracarboxylic acid dianhydrides are pyromellitic dianhydride and 3,3', 4,4'-benzophenonetetracarboxylic dianhydride. Representative fluororesin which can be used in this invention is polytetrafluoroethylene.

Polyimide resin-fluoropolymer compositions

Disclosed is a polarizing film containing a base resin and a photodichroic material which is characterized in that (1) the uniaxial orientation coefficient (f) of the principal crystal axis which is a crystal axis parallel to the molecular chain of the base resin, with respect to the reference axis is not less than 0.7 and (2) when a specimen of the polarizing film is cut out so as to have a surface perpendicular to the reference axis and X-rays impinging on the specimen parallel to the reference axis, the product (f.times.R) of the aforesaid uniaxial orientation coefficient (f) and the proportion (R=(I.sub.min /I.sub.max).times.100) of the minimum value (I.sub.min) to the maximum value (I.sub.max) of diffracted X-ray intensity on the resulting Debye-Scherrer ring is not less than 10. This polarizing film has excellent thermal resistance and moisture resistance and gives a high degree of polarization.

Polarizing film

A magnetic recording medium having a non-magnetic substrate on which a first bismuth Bi under layer, a first magnetic metal layer, a compound layer made of the magnetic metal, a second bismuth Bi under layer and a second magnetic metal layer are sequentially formed in this order.

Magnetic recording medium

A magnetic recording medium having a non-magnetic substrate, a bismuth layer of less than 100 .ANG. thick formed on one major surface of the non-magnetic substrate and a magnetic metal thin film formed on the bismuth layer.

Growing community of inventors

Yokohama, Japan

Kenichi Baba