| 摘要 |
This invention discloses a digital length gauge having an accuracy of about 0.01 mm. The digital length gauge includes a metal tape having a series of uniformly sized and spaced holes positioned along a common center line of the tape. As the tape is extracted and retracted from the length gauge housing, the holes engage pins positioned on a sprocket such that the sprocket will rotate causing an optical encoder to rotate along the same axis. The optical encoder produces optical pulses to provide the desired accuracy. The length gauge further includes a braking mechanism, an indexing mechanism and a drive motor. The braking mechanism prevents the reel on which the tape is wound from rotating in its normal mode. A braking arm and motor switch are configured relative to each other such that the braking arm has to deactivate the braking mechanism prior to the motor switch activating the drive motor. An indexing arm enables the reel to be incremented when the braking mechanism is activated. The length gauge also includes stops for providing a zeroing reference position, and a downwardly curving tape.
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