Abstract: A magnetic head having a head unit for contacting a magnetic medium comprises at least a pair of magnetic cores which are arranged in the head unit which face each other on sides of a magnetic gap for recording and/or reproducing signals. A spacer is included for maintaining a space between one of the magnetic cores and another member, which may be the other magnetic core or a shield member. The spacer includes a usable life detection device for providing an indication of wear on the head unit which is interrupted when the head unit is worn down to predetermined depth. A device for electrically sensing an interruption of the indication is provided so that a usable lifetime of the head unit can be determined.

Abstract: A transparent ocular lens material comprising a condensation polymer prepared by the condensation polymerization of a monomer mixture comprising (A) an aromatic tetracarboxylic acid dianhydride and (B) at least one diamino compound selected from (a) a silicon-containing diamine, (b) a diamino-substituted benzene and (c) a diamino-substituted diphenyl. The ocular lens material is excellent in transparency, having high oxygen permeability and moreover, excellent in heat resistance, ultraviolet-ray absorbing property and forming and processing property. Therefore, the ocular lens material can be suitably used in contact lenses, intraocular lenses, and the like.

Abstract: A printing apparatus for printing dots on a printing web comprises: a printer body frame; a single rotational drive motor for producing drive rotational force; rotational force transmission for transmitting the rotational force; a spring-biased link rotatable around a rotary shaft supported by the printer body frame; printing web feeding device; a printing drum having helical printing projections thereon, disposed so as to face the printing web, and supplied with the rotational force through the transmission at all times, the drum being rotatably mounted on the link; and an interlock including a transmission gear engaging with the drum and a ratchet gear engageable with a ratchet pawl pivotable in response to a solenoid to thereby achieve the printing shot by use of the single rotational drive motor when the solenoid is energized.

Abstract: A magnetic sheet or a magnetic slip with a magnetic tape or a magnetic coating on its back is driven intermittently by a sprocket wheel or a long roller. A rotating follower gives tension to the magnetic sheet. Between the follower and the drive roller, a magnetic head comes into sliding contact with the magnetic sheet when it stops for magnetic recording.