Patent ID: 7374356
Filing Date: 2008-05-20
Classification: B43K

Abstract:
1. A double-head writing instrument, comprising: a barrel formed by injection molding of transparent synthetic resin, the barrel opened at first and second ends thereof, the barrel having a partition formed therein; first and second ink-tanks provided inside the barrel and defined by the barrel and the partition so as not to communicate each other, the first and second ink-tanks opened at the first and second ends of the barrel, respectively; a first ink-retaining member connected with a first nib provided on an opening of the first ink-tank; a first ink reserved inside a first ink-reservoir which is provided inside the first ink-tank and at rear of the first ink-retaining member; a second ink-retaining member connected with a second nib provided on an opening of the second ink-tank; and a second ink reserved inside a second ink-reservoir which is provided inside the second ink-tank and at rear of the second ink-retaining member, wherein the first and second ink-retaining members retain temporarily the first and second ink spilled in accordance with an increase in pressure inside the first and second ink-reservoirs, respectively, the partition is extended in an axial direction of the writing instrument so as that the first and second ink-reservoirs overlap each other in a radial direction, and thickness C of the partition and thickness D of a side wall of the barrel connected with the partition satisfy a relation of 0.2≦C/D≦2.5, wherein inclined surfaces slanting relative to the axial direction are provided on an inner surface of the partition on the first ink-reservoir side and second ink-reservoir sides, respectively.