JPS59185151A - Linear motor - Google Patents

Abstract

PURPOSE:To improve the position detecting accuracy and to allow a linear motor to correspond to the long stroke by disposing a laser light source in a stator, providing a reflector in a movable element, and detecting a moving distance by a laser interference having an optical passage difference between both. CONSTITUTION:A movable element 2 provided with a reflector 7 on the side is movably provided at a wheel 8 on a stator 1 of a linear motor. On the other hand, a laser light source 12, a beam splitter 9, a reflecting prism 10 and a detector 11 are disposed on the end of the stator 1. The light which is reflected on the prism 10 through the splitter 9 from part of the laser light from the source 12 and the light which is reflected on the splitter 9 and the reflector 7 of the element 1 and returned are measured as interference fringe based on the optical passage difference by the detector 11. Accordingly, the moving distance of the element 2 can be accurately detected in micron order, and it can readily correspond to the long stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to position detection of a mover using an all-laser or a near motor.

Linear motors can be divided into induction type, blood flow type, and pulse type based on their driving method. Among these, the induction type utilizes the full thrust of the moving magnetic field of the stator and the attraction of the eddy DC magnetic field induced in the mover, so the moving magnetic field of the drive and the position of the mover are There is no 1. In the DC type, when the stator is a magnet and the mover is a coil, the current direction of the coil to obtain thrust is determined by detecting the entire magnetic field of the rainbow mover using a Hall element or the like.

The distance between the magnetic poles is at least t + q, which is μm.
It cannot be used as a positioning signal with order of magnitude accuracy. The pulse-type e-magani step is 1 minute, and the pulse-type e-magani step is driven by a stepped sine wave for 91 pulses during that time. Although it is decomposed into several tens of steps, its accuracy cannot be guaranteed due to the linearity of the magnetic flux. As mentioned above, if we try to obtain a method for detecting the position of the thigh of a linear motor (r), it is necessary to
position sensors will become indispensable.

The conventional method for detecting the position of a linear motor is as shown in FIG. Regarding the resistance value, 1. Something that detects all positions, and VC in Figure 2.
There are many devices in which a magnetic head 6 fixed to a moving element 2 detects a scale 5 magnetized in minute sections on the 7th floor. However, with the contact type method shown in Figure 1, there are problems with the stability and resolution of the contact part, and with the method shown in Figure 2, N
It is difficult to guarantee the uniformity of a and the accuracy of resolution VC'R on the order of microns. Moreover, Vζ, stator 1 like these
Detecting the position of a linear motor using a scale that also functions as a linear motor increases the cost depending on the length of the motor.
It cannot be said that it is a position detection device.

In the present invention, in order to eliminate the above-mentioned disadvantages, a laser is used to detect the displacement of the moving element. The purpose of this invention is to provide a single linear motor that is compatible with this invention.A detailed explanation of the following will be given with reference to FIG.

There is a mover 2 on top of the 1ml stator 1, and there is a reflection 1/7 on the side of the mover, and a wheel 8 is placed on the stator 1 at a distance of +J]? It can be kept and moved. A laser light source 12, a beam brick 9, a reflecting prism 10, and a detection section 11 are fixed to the shoulder of the stator 1. In operation, a portion of the laser light emitted from the laser light source 12 passes through the beam splitter 9, is reflected by the reflection prism 10, and reaches the cuff, detection @, 1ivc. The other beam is reflected by the beam splitter 9, reflected in the opposite direction by the reflector 7 fixed to the movable element 2, passes through the beam splitter 9'JT again, and enters the detection section 11.

In this case, what is the difference between the two optical paths? 'One Beam Splitter 9
Since the round trip of the reflecting prism 10 is fixed from
From the beam splitter 9 to the reflector 7, that is, the identifier 2
It varies depending on the distance at 1. Since laser light is coherent, the detection section 11 that receives all of the laser light that has passed through two different optical paths can measure interference fringes based on the optical path difference. The period is half the wavelength λ of the laser light, so
Every time the distance between the beam splitter 9 fixed to the stator 1 and the movable element 2 changes by λ/2, the interference fringes of the detection section are measured, and by counting the number of fringes, the moving distance of the movable element 2 can be measured. Also, although not shown, there is an optical path difference between the laser beams! It is clear that if the detector 11 has an optical path difference corresponding to a phase difference of 1l190° or less and the optical path is available, it is possible to detect a phase difference of 1cJ:,0 in the moving direction.

In position detection using this unconventional laser beam, there is peace of mind that the laser beam in space is continuous, so it is conceivable to add a cover, etc. However, as shown in factors 4 and 5, the optical path can be fixed with a stator. Stable operation can be ensured by placing it in the concave part and creating a structure that is difficult to block from the IIS part.

More than,! If the present invention is applied to c), it becomes possible to detect the moving distance on the order of 1 micron by using a laser to detect the position of the moving element of a linear motor, and the long grass can be moved over a long distance of am by just the convergence of the laser beam. However, it can be done with the same system, and the cost of the position sensor will be lower overall. By configuring all of the 1L laser source paths in the concave portions of the stator, a great effect can be expected in that it also serves as a cover for the source path and allows for stable operation.

[Brief explanation of drawings]

Figures 1 (9) and 2 are side views showing the conventional position detection method, and Figure 2 is a side view of the embodiment of the present invention. FIG. 4 is a front sectional view of the second embodiment of the present invention. Fig. 5 is a side view of the second embodiment of the present invention, 1... Stator 2... Mover 3
......Linear potentiometer 4...Slider 5...Magnetic scale 6...Yamaki head 7...Reflector 8
...Car import 9...Beam splitter 10...Reflection prism 11...
・Detection unit 12... Laser light source and above Figure 1 3 / 20 - Figure 4/2 Negative figure

Claims (1)

[Claims] (il) A linear stator and a linear stator that moves along the stator, or a near motor, and the stator - the light source waits, and a reflector is attached to the mover. 111,
A linear near motor characterized in that a moving distance detecting means is laser source interference that uses an optical path difference between the front bow body stator and the movable element. The linear motor according to claim 1 is characterized in that the concave portion is fixed.