The most common type of frame display is a two-frame type. This simply relies on displacement of pump or metal to transition between two frames. However, other methods are possible. One method is to use a grid of joints instead of single lines, which interchange regularly. This allows for a maximum of four frames. Another method is to uses several joints placed side-by-side in large columns. These columns are generally then moved via wind generated from fan or other sources such as fire.
Like the mercury switch, the frame display originated in a Japanese upload. スリットアニメもどき by under/shaft is the first known upload to include a frame display. Since then, they have been adapted to display several frames, instead of two. They are often usually used as a decoration within an upload and not standalone.
A well known frame display, スキャニメーション by としあき, shows a looping 5-frame animation (10-frame counting transitions) of a galloping horse.
How it works
The frames in a frame display are located between two parallel lines of pump, which are the same length and joined across at two-pixel increments. Two dots of a liquid (mercury is most commonly used), one for each line, enters their line at the same time in respect to the same place. As the liquid travels through the lines, it passes through the joined ends of the pump, and, in turn, switches places with them. Because the location of the joint has changed one pixel, it uncovers part of the second frame. At the end of the lines of pump, the second frame is fully revealed, and the liquid loops around to re-reveal the first frame. Thunder and metal can also be used.