Free ink system

A marking instrument for dispensing as fluid, including a housing and reservoir for storing the fluid disposed in the housing comprising:

• a feeder for conveying fluid to a marking tip from the reservoir;
• a passage of reduced capillarity relative to the feeder for conveying at least one of fluid and air to the reservoir;
• a buffer disposed between the housing and the passage and configured for storing the fluid;
• and
• a divider tube separating the buffer and the passage;
• whereby the fluid and air may enter the feeder through a portion of the buffer during an increasing pressure differential;
• and
• wherein the tip has a greater capillarity than the feeder, the feeder has a greater capillarity than the buffer and the buffer has a greater capillarity than the passage of reduced capillarity.

A marking instrument for dispensing a fluid, including a housing and a reservoir for storing the fluid disposed in the housing comprising:

• a feeder for conveying fluid to a marking tip from the reservoir;
• a passage of reduced capillarity relative to the feeder for conveying at least one of fluid and air to the reservoir;
• a buffer disposed between the housing and the passage and configured for storing the fluid;
• and
• a divider tube separating the buffer and the passage;
• whereby the fluid and air may enter the feeder through a portion of the buffer during an increasing pressure differential;
• and
• wherein the divider tube and the buffer are generally coaxial and the buffer extends a greater length toward the marking tip than does the divider tube.

An ink and air conveyor for use in a free ink marking instrument for dispensing ink onto a substrate such as paper, the instrument including a housing having an interior including a reservoir for storing the ink and a marking tip coupled to the housing comprising;

• a divider tube supported along an axis of the marking instrument;
• a feeder disposed within the divider tube and extending outwardly therefrom toward the marking tip;
• a buffer surrounding a portion of the feeder and extending outwardly from the divider tube;
• and
• a channel adapted for conveying at least one of fluid and air located between an exterior surface of the feeder and an interior surface of the divider tube.

A method for compensating for changes in ambient temperature and pressure in a free ink marking instrument including a housing, a marking tip coupled to the housing, a buffer, a divider tube generally parallel to a wall of the housing, a feeder configured for conveying air and ink, a first portion of the feeder extending into the divider tube and spaced from an inner wall thereof, a second portion of the feeder attached to the inner wall of the divider tube, a third portion of the feeder extending outwardly from the divider tube toward the marking tip comprising:

• drawing air from the atmosphere through a vent near the marking tip to the interior of the housing;
• urging the air through the buffer;
• urging the air from the buffer to the third portion of the feeder;
• urging the air from the third portion of the feeder to a channel;
• and
• urging the air from the feeder to a location between the feeder and the inner wall of the divider tube.