1. Field of the Invention
The present invention relates to a fixing structure of a flat cable connecting portion in a rotary connector.
2. Description of Related Art
A rotary connector has a flat cable, which is a flexible, belt-shaped electric wire and which is wound into a coil to be housed in a annular space formed by a rotary case and a fixed case. These cases are allowed to perform relative rotation between them, a connecting portion on one end of the flat cable being mounted on the fixed case, while a connecting portion on the other end being mounted on the rotary case. The relative rotation between the cases is made possible by the flat cable windable or unwindable as the foregoing rotary case rotates. In this case, the flat cable is a belt-shaped transmission line comprised of a plurality of electrical conductors (not shown) covered with an insulator.
In such a rotary connector, the connecting portions of the foregoing flat cable are fitted in connection housings provided in the respective cases, then fixed to the connection housings by fixing components attached to the respective cases. Here, the rotary connector allows the relative rotation between the cases by the coiled flat cable's tightening or loosening as described above. For this reason, various types of stress such as tension and compression cuts on the connecting portions as the coiling flat cable is wound or unwound in the rotary connector.
Therefore, it is necessary to securely fix the connecting portions of the flat cable to the cases. Conventionally, to fix the connecting portions of the cases by installing fixing components on the cases, the fixing components are fixed to the cases by, for example, a plurality of rivets, or by providing the fixing components with locking hooks whereby the fixing components are attached to the cases.
When the fixing components are riveted to the cases with rivets to mount the fixing components to the cases, the number of processes for assembling the rotary connector increases, raising a problem of poor work efficiency.
On the other hand, when the fixing components are installed to the cases by locking hooks, the installation can be completed readily; therefore, it is easy to install and also easy to check for proper engagement due to a click which is felt when the hooks engage with the case. However, the locking hooks may disengage from the cases during the use of the rotary connector, and the installation may not necessarily be secure.
In addition, the rotary connector is normally provided with components for preventing reversion in the vicinity of the connecting portions of the flat cable, which components are called end supports and have function to prevent buckling causable by the flat cable's reversing when the cases rotate near a limit of the winding or unwinding of the coiling flat cable. For this reason, the rotary connector required two types of components, i.e., the components for preventing reversion and the fixing components, adding to the number of parts with consequent inefficiency in the aspect of parts control.
USPTO Backgrounds
USPTO Backgrounds