How was the ball point pen invented?

The first model of a ballpoint pen was patented in 1888 by an American, John H. Loud, for writing on rough surfaces. But a successful ballpoint pen, like the modern one, could not be developed till 1943. In fact, the American Air Force is mainly responsible for its invention. The Air Force demanded a special type of pen, which could be used by the aircraft crew during flights. They required a pen, which would not spill ink due to the reduction in air pressure at high altitudes. Such a pen could only be a ballpoint pen and hence, there was a very fast development of it after this demand. Later, it became so popular that even the common people began to use it. The ballpoint pen has a hollow body made up of some metal or plastic material. It has a cap, a spring and an ink-refill with a tiny brass ball (writing point) fitted at one end. The cap controls the writing point. The spring helps the writing point to move up and down. The refill is generally made of polythene and is filled with different colours of ink. The ink used in ballpoint pen is specially formulated to be thick so that, it may not leak. Its flow, however, remains smooth and unbroken lines can be drawn with the help of these pens. The ink is drawn through internal ducts in the socket by capillary action (a phenomenon in which the surface of a liquid confined in a narrowbore tube rises above level). A ballpoint pen has many uses. No blotting paper or inkpot is needed when it is used. This pen writes fast and its ink does not spill on paper. The words written by it are not affected by water. It has certain disadvantages also. Unlike a fountain pen, it does not make broader or finer strokes. It tires the hand more quickly than an ordinary pen because more pressure has to be exerted while using it. In the 1960s, soft-tip pens were developed in Japan. In these pens, the ink flows through a pad when pad touches the writing surface. During 1980s, ballpoint pens with carbide tips became very popular.