Abstract: The object of the present invention is to provide a needle type ballpoint pen chip capable of achieving smooth writing. The needle type ballpoint pen chip of the present invention has a very small diameter, the diameters of the ball and the ink flow hole are naturally also small. In order to achieve smooth writing, it is therefore necessary to minimize to the greatest extent possible deviation in the position of the center axis line of the ink flow hole in relation to the center of the ball. To achieve the object, in the needle type ballpoint pen chip of the present invention, a solid cylindrical steel material S with a diameter of approximately 1 mm or less, rather than a pipe material, is used as its base material, and an ink flow hole is formed by performing drill cutting processing on this steel material.

Abstract: A thermal head device for use in a facsimile machine and the like as an output device is provided. The thermal head device comprises a plurality of heat-producing electrically resistive elements formed on an insulating substrate arranged in a single line to form a thermal array. A plurality of tape carriers, each comprised of an insulating film strip and conductive paths formed thereon in a desired pattern, are used to provide interconnections between the resistive elements and external circuits. An image information signal is applied to the resistive elements through the tape carriers thereby the resistive elements are selectively activated to produce heat in accordance with the signal supplied. Therefore, a visual image may be obtained by advancing a thermosensitive paper in contact with the thermal array in the direction perpendicularly thereto. The present invention provides numerous improvements in such a thermal head device.