LINEAR DRIVE APPARATUS

Abstract

A linear drive apparatus comprising: a guide having an internal body; a slider moved along the guide, a driving mechanism for generating a driving force by magnetic interaction of the slider with the guide so as to linearly drive the slider; and a magnetic measurement unit having a magnetic scale and a detector which are opposed to each other and change a relative position relative to each other in order to obtain the relative position of the slider relative to the guide, wherein an opposing direction of the magnetic scale and the detector is the direction of the outer circumference of the guide, and the detector detects a signal from the magnetic scale in accordance with the relative position of the slider, whereby the relative position of the slider is obtained.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above object, and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the appended drawings, in which:

FIG. 1 is a perspective view showing a linear drive apparatus according to an embodiment of the present invention;

FIG. 2 is a sectional view showing the longitudinal section of the linear drive apparatus of FIG. 1; and

FIG. 3 is a sectional view showing the transverse section of the linear drive apparatus of FIG. 1.

Claims

1. A linear drive apparatus comprising: a guide;a slider moved along the guide;a driving mechanism for driving the slider in a straight line, anda magnetic measurement unit having a magnetic scale and a detector that are opposed and change a relative position relative to each other in order to obtain the relative position of the slider relative to the guide,wherein a direction of opposition of the magnetic scale and the detector intersects a direction of lines of magnetic force of a surrounding external magnetic field, and the detector detects a signal from the magnetic scale in accordance with the relative position of the slider,whereby the relative position of the slider is obtained.

2. A linear drive apparatus according to claim 1, wherein the slider is supported by a pneumatic bearing.

3. A linear drive apparatus comprising: a guide having an internal magnetic body;a slider moved in a straight line along the guide;a driving mechanism for generating a driving force by magnetic interaction of the slider with the guide so as to linearly drive the slider; anda magnetic measurement unit having a magnetic scale and a detector which are opposed to each other and change a relative position relative to each other in order to obtain the relative position of the slider relative to the guide,wherein an opposing direction of the magnetic scale and the detector is a direction of an outer circumference of the guide, and the detector detects a signal from the magnetic scale in accordance with the relative position of the slider,whereby the relative position of the slider is obtained.

4. A linear drive apparatus according to claim 3, wherein the magnetic body comprises a permanent magnet or a center bar magnetized by a surrounding magnetic force.

5. A linear drive apparatus according to claim 3, wherein the slider is supported by a pneumatic bearing.