
B-65382EN/02 HANDLING, DESIGN, AND ASSEMBLY 2.MECHANICAL DESIGN
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2.6 MOUNTING A LINEAR ENCODER
2.6.1 Mounting Rigidity and Noise Protection
The linear motor is controlled using only a feedback signal from the
linear encoder. This means that if the mounting rigidity of the linear
encoder is insufficient, a feedback signal can pick up noise such as
mechanical vibration, resulting in a problem such as degraded
precision and uncontrollability. Be sure to mount a linear encoder with
a high rigidity so that it does not pick up peripheral vibration. Set the
rigidity (natural frequency) of the head mounting portion to 2 kHz or
more as a guideline. Moreover, ensure that a linear encoder is
mounted with the specified precision.
If a feedback signal from the linear encoder picks up noise from
another electric system, a problem similar to the problems mentioned
above can occur. Ensure that the feedback signal cable is sufficiently
shielded and grounded, and that the feedback signal cable does not run
across or along with the motor power line.
2.6.2 Linear Motor and Linear Encoder Directions
To drive a linear motor normally, the positive direction of the linear
motor and the positive direction of the linear encoder must match each
other.
CAUTION
If the direction of the linear motor does not match
the direction of the linear encoder, the motor can
become uncontrollable in the worst case. In
mechanical design and assembly, ensure the
matching of the directions.
Positive direction of a linear motor
The positive (plus) direction of a linear motor depends on whether the
coil slider is movable or the magnet plate is movable. The positive
direction can be determined from the direction of power line running
direction.
- When the coil slider is movable
Positive
direction
Slider movable
Magnet plate fixed
Power line