This invention relates to pens which utilize a fluid ink and whose writing tips are axially positionable with respect to an outer sheath.
Various types of pens using an aqueous or non-aqueous fluid are in widespread use for writing, drawing, painting or marking purposes, and may collectively be referred to as marking pens. Said fluids, which may be inks having soluble dyes, or paints having dispersed pigments, may be generically referred to as marking fluids. Many of such pens are provided with protective caps which prevent evaporation of the fluid and prevent accidental contact of the fluid with the clothing or skin of the user or with other objects. However, the placement and removal of the cap is troublesome, and the cap is frequently misplaced.
Marking pens which avoid the need for a protective cap are well known and generally employ a mechanism whereby the tip of the pen can be retracted into a protective enclosure within an elongated sheath comprising the outer body of the pen. Marking pens of such construction are disclosed for example in U.S. Pat. Nos. 4,218,154; 3,652,172; and 4,540,300. The protective enclosures and associated retracting mechanisms are, however, generally of complex, expensive construction and do not endure long term use.
Accordingly, it is an object of the present invention to provide a retractable capless marking pen having a protective enclosure within the body of the pen that prevents evaporation of marking fluid from the tip of the pen.
It is a further object of this invention to provide a marking pen as in the foregoing object of rugged and durable construction amenable to low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.