Patent ID: 7037015

Claim:
A writing pen for use with free-flowing, low viscosity, pigmented inks subject to pigment sedimentation, which comprises (a) a pen body including an upper portion for retaining a supply of low viscosity, pigmented ink, (b) a supply of low viscosity, pigmented ink contained in said upper portion, (c) means forming a confined air space above said ink, (d) a nib structure joined with a lower portion of said pen body and having internal passage means communicating with said upper portion for receiving ink from said supply thereof, (e) a roller ball assembly at a lower end of said nib structure and comprising a roller ball and a socket retaining said roller ball and provided with a capillary flow passage to accommodate the flow of ink to a back portion of said roller ball, (f) a capillary system providing communicating between said supply of ink and the atmosphere to accommodate expansion and contraction of said ink and of air in said air space resulting from changes in pressure and temperature, and (g) an axially movable agitating element contained at least in part within the internal passage means of said nib structure and immersed in said ink, (h) said agitating element being reciprocally movable within said nib structure by shaking of said pen and being shaped and contoured to sweep said internal passage and to re-disperse pigment sedimented therein to enable the free flow of pigmented ink to said roller ball, (i) said agitating element including a portion associated with said capillary flow passage and operative to clear said capillary flow passage when said agitating element is reciprocated.