Bíró Ballpoint Pen

Chances are, you have a ballpoint pen on your desk or on your person right now. The ballpoint pen is a reliable tool we use all the time.

The ballpoint pen that we know today was invented by László József Bíró. Although Bíró was not the first to create a ballpoint pen, his invention was the first to work consistently.

Bíró was a journalist and he noticed that the ink used to print newspaper dried quickly and didn’t leave smudges like the fountain pens at the time. He tried using this ink in a fountain pen, but it would not flow properly because the ink was too thick. So Bíró’s brother, a chemist, developed a viscous ink while Bíró invented the new pen.

There is a lot more to the story of Bíró’s life and his ballpoint pen, but here, we will take a look at his US patent filed on 17 June 1943 - US granted patent no. 2390636.

The pen body

The pen ink stored in a reservoir (b) moves down the conduit (c) due to gravity. The ink passes through channels (6) and touches the surface of the ball (2) such that the ball is covered with ink. The ball rolls as the user writes, the inked portion of the ball touches the paper and leave a mark. The ink will continue to flow down from the reservoir, replenishing the supply of ink.

It's interesting how the shape of the pen cartridge hasn't changed in the last 70 years.

Figures 5 and 6 of US granted patent no. 2390636

The ballpoint

Figures 1 and 2 of US granted patent no. 2390636

Ink is distributed through the hollow portions of the concave socket (e) to the rim of the ball setting. The ball is held in place by the seats (4) and the rim (3). The ball is able to roll freely in this housing allowing strokes to be drawn in any direction but will not fall out.