There are two main types of roller ball pens: liquid ink pens and gel ink pens. The 'liquid-ink' type uses an ink and ink supply system similar to a fountain pen, and they are designed to combine the convenience of a ballpoint pen with the smooth "wet ink" effect of a fountain pen. The 'liquid-ink' type rollerball pens were introduced in 1963 by the Japanese company Ohto. The gel ink type rollerball pens were patented in 1982 by Sakura Color Products.