Patent ID: 8898871

Claim:
An operation cord comprising: a main cord having one and the other ends, the main cord having a length direction defined between the one and the other ends; a first coupling part disposed at the one end; and a second coupling part disposed at the other end, the first and second coupling part being formed of a synthetic resin, wherein the first and second coupling parts configured to be coupled together directly or via a coupling member formed of a synthetic resin and configured to be coupled or uncoupled by means of a relative rotation between the adjacent coupling parts, or a relative rotation between the adjacent coupling parts and coupling member, wherein balls formed of a synthetic resin are disposed on the main cord at regular intervals, and when the first and second coupling parts are directly coupled, the first and second coupling parts in combination, form substantially the same shape and size as that of the ball, and when the first and second coupling parts are coupled via the coupling member, the first and second coupling parts and the coupling member in combination form substantially the same shape and size as that of the ball, the first coupling part and the second coupling part are configured to be separatable by resilient deformation of the synthetic resin of at least one of the first coupling part, the second coupling part, or the coupling member, which is caused by a second pull force applied to the operation cord substantially along the length direction without relative rotation between the adjacent coupling parts or relative rotation between the adjacent coupling parts and coupling member, the second pull force exceeding a first pull force applied to the operation cord on normal operation.