Abstract: A unitary plotter pen construction useful as a disposable plotter pen. A writing tube is provided centrally and at the front end of a unitary hard plastic body element that defines a writing tube nib; a housing for a soft plastic pressure equalization chamber and an ink reservoir; and an adaptor structure for mounting with a plotter head. An axially extending pressure-equalization chamber is defined by soft plastic, lamella vent channel element that is inserted from the rear and axially against inner surfaces of the hard plastic body element. An upper end of the pressure-equalization chamber connects to the ink supply and a lower end connects to ambient air, through an annular cavity at the front end of the unitary body element. That annular cavity also may include transverse capillary spaces as a further protection against ink leakage from the pressure equalization chamber.

Abstract: A technical pen, in particular for use in a drafting instrument such as a plotter, with a writing tube (4) fixed in the front end of a pen tip (1, 2, 3), into which a cleaning wire (5), fastened to the front end of a drop weight body (6), extends, has a device (20, 23, 24) for monitoring the writing fluid level in a buffer chamber (15) disposed between the front end of the inner bore (7) and the back end of the writing tube (4) as well as for activating a conveying means (25) for transporting writing fluid from the inner bore (7) into the buffer chamber (15) when the writing fluid has fallen below a pre-determined level. The buffer chamber (15) is formed centrally symmetrical in relation to the center axis of the writing tube (4) and its inner and outer boundary walls (16, 17) converge from the front to the back. The front area of the buffer chamber (15) is connected with the writing tube ( 4) and the inner bore (7), while its rear area is closed.

Abstract: A stylo pen tip, in particular for use in drafting plotters, has a writing tube (5) in the front end, into which a cleaning wire (6) extends from the rear, which is fixed at the front end of a drop weight body (7) which is movable back and forth axially to a limited degree in an inner bore (8). The inner bore (8) is connected with a writing fluid reservoir (4), which surrounds at least the front section of the inner bore. Coaxially to the inner bore (8), a pressure equalization chamber (11) is provided, the inner end of which is connected with the writing fluid reservoir (4) and the outer end of which is connected with ambient air. At least a portion of the pressure equalization chamber (11) is surrounded by the writing fluid reservoir (4). The inner end of the pressure equalization chamber (11) lies on the front end of the inner bore and its outer end in the area of the back end of the stylo pen tip.

Abstract: A stylo pen tip has a front part (2) supporting the writing tube (6), on which a writing fluid cartridge (10) has been placed from behind with its front section. The front end area of the writing fluid cartridge (10) forms a narrowed, elastically stretchable opening cross section (12) which, in the operating position, grasps a protrusion area (8) formed on the front part (2) from behind. An auxiliary tool (19, 20) can be placed from the front on the front part (2) and can be brought into stretching engagement with the stretchable opening cross secion (12) of the writing fluid cartridge (10) in order to allow a separation of the front part (2) and the writing fluid cartridge (10) from each other.

Abstract: A stylo pen tip with a drop weight body (7) which is located inside an inner bore (6) of a housing (1,1') connected with the writing fliud reservoir (16) and which has a cleaning wire (8) at its front end extending into the writing tube (2) supported on the front end of the housing (1, 1') has a drop weight safety (13) supported therein which is pivotable around the longitudinal axis of the housing (1,1') and which is in interlocking contact with the drop weight body (7), which can be moved back and forth axially in a limited way in relation to it. In its forward position the drop weight body (7) adjoins with its front end (10) a stop face (9) formed in the inner bore (6). The plane of the front end (10) of the drop weight body (7) and the plane of the stop face (9) are inclined towards each other. By turning of the drop weight body ( 7) the extension of the cleaning wire (8) beyond the front end of the writing tube (2) can be adjusted.