Importance

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Abstract

An improved encoder for indicating angular position or rotation of a shaft, and particularly a digital encoder for use with materials handling vehicles, includes an index mark in an index band of the encoder that is made wider than the marks in the data tracks. Associated detecting circuitry is responsive to the wide index mark for creating a dead band around a neutral position of the encoder to permit the free movement of the encoder shaft by an angular amount determined by the width of the index band. The wide index band enlarges the tolerance permitted in the return of the shaft to its neutral position and when installing the encoder on a shaft. When an encoder having a wide index band is used with a control handle, such as in positioning devices and accelerators on materials handling vehicles, the control handle has an improved feel and response. The wide index also provides a safety factor in that slight movement of the shaft due to vibration or accidental touching of the control handle will not normally evoke a response since the rotational angle exceeds the index band before an output is generated. Circuit may also be provided to control the profile of the output signal in response to the amount of angular rotation of the encoder.

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First Claim