Encoder for monitoring bidirectional motion

In a rotational encoder apparatus having a plurality of indicia at fixed positions with respect to each other, means for rotating said indicia about an axis and means for sensing said indicia positioned along the path of rotation of said indicia, the improvement

• wherein each of a plurality of said indicia has first and second non-parallel edges non-radial to said axis and traversing said path of rotation,
• and
• further including means for moving said sensing means so that the position of said sensing means may be adjusted with respect to said first edges which are the leading edges when said indicia are rotated in one direction and to said second edges which are the leading edges when said indicia are rotated in the opposite direction.

In a closed loop bidirectional step motor system comprising a bidirectional step motor rotating through each motor revolution in a predetermined number of equal steps, an encoder rotating in synchronization with said step motor and having a plurality of indicia each respectively corresponding to at least a fixed portion of a motor step and means for sensing said indicia positioned along the path of rotation of said indicia, the improvement

• wherein each of said indicia has a first edge radial to the axis of said path of rotation and traversing said path and a second edge non-radial to said axis, traversing said path, and
• further including means for moving said sensing means so that the position of said sensing means may be adjusted with respect to said first edges which are the leading edges when said indicia are rotated in one direction and to said second edges which are the leading edges when said indicia are rotated in the opposite direction whereby the lead angle of said sensing means may be adjusted for each direction of rotation of said step motor.

In a closed loop bidirectional step motor system comprising a bidirectional step motor rotating through each motor revolution in a predetermined number of equal steps, an encoder rotating in synchronization with said step motor and having a plurality of indicia each respectively corresponding to at least a fixed portion of a motor step and means for sensing said indicia positioned along the path of rotation of said indicia, the improvement

• wherein each of said indicia has first and second non-parallel edges non-radial to the axis of said path of rotation and traversing said path,
• and
• further including means for moving said sensing means so that the position of said sensing means may be adjusted with respect to said first edges which are the leading edges when said indicia are rotated in one direction and to said second edges which are the leading edges when said indicia are rotated in the opposite direction whereby the lead angle of said sensing means may be adjusted for each direction of rotation of said step motor.

In an encoder apparatus having a plurality of indicia at fixed positions with respect to each other, means for moving said indicia along a directional linear path and means for sensing said indicia positioned along said path, the improvement

• wherein each of a plurality of said indicia has a first edge perpendicular to said path and traversing said path and a second edge non-perpendicular to said path traversing said path,
• and
• further including means for moving said sensing means so that the position of said sensing means may be adjusted with respect to said first edges which are the leading edges when said indicia are moved in one direction and to said second edges which are the leading edges when said indicia are moved in the opposite direction.

In a closed loop bidirectional step motor system comprising a bidirectional step motor moving in a number of equal steps, an encoder moving in synchronization with said step motor and having a plurality of indicia each respectively corresponding to at least a fixed portion of a motor step and means for sensing said indicia positioned along the path of said indicia, the improvement

• wherein each of said indicia has a first edge perpendicular to said path and traversing said path and a second edge non-perpendicular to said path traversing said path, and
• further including means for moving said sensing means so that the position of said sensing means may be adjusted with respect to said first edges which are the leading edges when said indicia are moved in one direction and to said second edges which are the leading edges when said indicia are moved in the opposite direction whereby the lead angle of said sensing means may be adjusted for each direction of movement of said step motor.