Ring binder

Ring binders (loose leaf binders, looseleaf binders, or sometimes called files in Britain) are large folders that contain file folders or hole punched papers. These are held in the binder by circular or D-shaped retainers, onto which the contents are threaded. The rings are usually spring-loaded, but can also be secured by lever arch mechanisms or other securing systems. The binders themselves are typically made from plastic with metal rings. Early designs were patented during the early 1890s to the early 1900s.

German Friedrich Soennecken invented ring binders in 1886 in Bonn, Germany. He also registered a patent on November 14, 1886, for his Papierlocher für Sammelmappen ("paper hole maker for folders", or hole punch). German Louis Leitz, founder of Leitz later made some important changes in development of ring binders in Stuttgart-Feuerbach. Leitz introduced the "finger hole" on the side of the binder to aid removal from crowded shelves.

The ISO standard two holes are 80 millimetres (3.1 in) apart, according to ISO 838. The four-hole version has no ISO standard. The distances between holes are 80 millimetres (3.1 in) (3×8).

Another design for ring binders was invented in 1889 by Andreas Tengwall in Helsingborg, Sweden, and patented in 1890 under the name 'Trio binder', named after a business consortium of Tengwall and two associates. Tengwall's design uses four rings, in two paired sets. The hole placement of Tengwall's Trio binder is still used as a de facto standard for hole punching in Sweden under the name triohålning. These holes are 21 millimetres (0.83 in), 70 millimetres (2.8 in), and 21 millimetres (0.83 in) apart. (In this article, it makes mention that, according to the curator of the Early Office Museum in London, the first patent for ring binders was filed in 1859 for a two-ring binder. A few years later three-ring binders became the standard in the United States; the "D" ring binders did not come on the market there until the 1940s or 1950s.)

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