| 摘要 |
The tape measure may consist of a relatively large tape blade. To accommodate a large blade the tape measure housing is formed as a hollow annulus having an open central core where the blade is wound about the core of the annular housing. Because the housing has a central opening it can be easily carried in one hand. The device also includes a locking mechanism for locking the tape in an extended position and a rewind mechanism for rewinding the tape back into the housing. The rewind mechanism may comprise a belt drive, opposed springs with a cam lock, a linear spring compressed by a gear drive, a motor driven gear drive, a flat spring and gear drive or a magnetic drive.
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