JPH0483221A - High-accuracy galvanomirror driving system - Google Patents

Abstract

PURPOSE:To secure high accuracy by coupling a fine swing mechanism with a driving system which drives a galvanomirror with an electromagnetic force in series, and providing a swing angle detecting mechanism which feeds a swing angle back and performing dynamic control. CONSTITUTION:The high-accuracy swing angle detecting mechanism 4 is provided to the swing axis 2 of the galvanomirror 3, the fine swing mechanism 5 is coupled in series, and a swing angle which is detected by the detecting mechanism j4 is fed back to drive and control the galvanomirror 3. An optical encoder, etc., which has accuracy about two digits higher than the accuracy of an electromagnetic driving device 1 driving the galvanomirror 3 is used as the swing angle detecting mechanism 4 and elements 5a and 5b which can perform fast fine displacement control are used as the fine swing mechanism 5. Consequently, the galvanomirror can be driven at a high speed with the accuracy of the swing angle detecting mechanism within the swing angle range of the driving system which performs the electromagnetic force driving.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a high-precision galvanometer mirror drive system used in optical equipment, particularly in a control system for deflecting a light beam.

[Prior Art] A galvanometer mirror is generally constructed by installing a plane mirror so that it can swing around an axis included in its plane. The swinging motion of the galvanomirror is normally driven by electromagnetic force, but it is controlled in an open loop and has low accuracy. That is, even if a specific rocking angle is set, in reality, the angle will constantly deviate from the set angle due to jitter or the like.

[Problems to be Solved by the Invention] The technical problem of the present invention is to connect in series a micro-oscillation mechanism configured by another highly accurate drive element to an existing drive system that drives a galvanomirror using electromagnetic force. In addition, a galvanomirror drive is provided with a swing angle detection mechanism that feeds back the swing angle for dynamic control, thereby ensuring high accuracy in the swing angle range of the drive system caused by the electromagnetic force. The aim is to provide a system.

[Means for Solving the Problems] A high-precision galvano mirror drive system of the present invention for solving the above problems is a galvano mirror drive system that electromagnetically generates rocking motion with respect to the rocking axis of the galvano mirror. ,
A swing angle detection mechanism is provided on the swing shaft to detect the angle at which it swings due to the electromagnetic force, and a micro swing is provided on the swing shaft to micro swing the galvanomirror at high speed and with high precision. The mechanisms are arranged coaxially, and further, the micro-oscillation mechanism compensates for an error angle between the actual swing angle of the swing axis and the control target angle based on the detection output of the swing angle detection mechanism. It is characterized by comprising a control means.

[Function] When a drive current is applied to the drive system that drives the galvanomirror using electromagnetic force, the swing angle of the swing axis fluctuates, making it impossible to set a highly accurate angle, but the swing angle detection mechanism When the swing angle is detected by the control means and the high-precision minute swing mechanism is controlled to cancel the error angle between the actual swing angle of the swing axis and the control target angle, the electromagnetic force The galvanomirror can be driven at high speed with the accuracy of the swing angle detection mechanism within the swing angle range of the drive system that performs the drive.

[Embodiment] FIGS. 1 and 2 show an embodiment of a galvanomirror drive system according to the present invention.

This galvanomirror drive system is basically a system in which a swing shaft 2 of a galvano mirror 3 is attached to an electromagnetic drive device 1, and the swing shaft 2 is caused to swing by electromagnetic force. A highly accurate swing angle detection mechanism 4 is provided on the swing shaft 2, and a micro swing mechanism 5 composed of a highly accurate drive element is connected in series, and the swing angle detected by the detection mechanism 4 is fed back. By doing so, the galvanomirror 3 can be driven and controlled with the accuracy of the swing angle detection mechanism 4.

As the swing angle detection mechanism 4, an optical encoder or the like having an accuracy two fingers higher than the precision of the electromagnetic drive device 1 that drives the galvanometer mirror 3 is preferably used. A fixed part 4a of the moving angle detection mechanism 4 is fixed, and a rotating part 4b thereof is fixed to the swing shaft 2.

Furthermore, as the micro-oscillation mechanism 5 attached to the above-mentioned swing shaft 2, an element 5 capable of high-speed micro-displacement control such as a piezo element is used.
a and 5b, and the galvanomirror 3 is mounted so as to rotate slightly coaxially with the swing shaft 2.

That is, the mirror fixing base 6 is attached to the tip of the swing shaft 2.
A galvanometer mirror 3 is attached to both side edges of this mirror fixing base 6 via piezo elements 5a and 5b, and at this time, the galvanometer mirror 3 is arranged so as to rotate slightly coaxially with the swing axis 2. .

Therefore, the galvanometer mirror 3 at the tip of the swing shaft 2 is driven by the amount by which the movement of the electromagnetic drive device 1 and the movement of the micro swing mechanism 5 are superimposed.

Also, although not shown on the side 4 of the Joki swing angle detector,
A control means for feeding back the detected swing angle is attached. This control means determines the error angle between the actual swing angle of the swing shaft 2 and the control target angle based on the detection output of the swing angle detection mechanism 4, and calculates the error angle between the actual swing angle of the swing shaft 2 and the control target angle.
In order to compensate for this, an output is sent to the micro-oscillation mechanism 5 to drive it.

FIG. 3 shows a time chart during operation of the galvanometer mirror drive system.

When the drive current shown in FIG. 12A is applied to the electromagnetic drive device l, the swing angle of the swing shaft 2 fluctuates as shown in FIG. Therefore, in order to cancel out the fluctuation part of the swing axis 2 and prevent the above fluctuation from being transmitted to the galvanometer mirror 3, as shown in FIG. As a result, one piezo element expands and the other contracts, so that the galvanometer mirror 3 is slightly rotated relative to the mirror fixing base 6.

By driving the minute swing mechanism 5 at high speed as described above based on the output of the swing angle detection mechanism 4, the galvanometer mirror 3
As shown in the same figure, the swing angle does not fluctuate, and as a result, the galvanometer mirror can be detected with the accuracy of the swing angle detection mechanism 4.
A highly accurate galvanometer mirror drive system capable of driving 3 can be realized.

[Effect of the invention 1] According to the high-precision galvano mirror drive system of the present invention detailed above, the existing drive system that drives the galvano mirror by electromagnetic force is replaced with a microscopic drive system configured by another high-speed and high-precision drive element. In the swing angle range of the drive system due to the electromagnetic force, the swing mechanism can be connected in series and dynamically controlled by providing a swing angle detection mechanism that feeds back the swing angle. A galvanometer mirror drive system capable of compensating for high accuracy can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, FIG. 1 is a front view thereof, FIG. 2 is a partially cutaway perspective view of the main part, and FIG. 3 fa) to (e).
is a time chart during operation of the galvano mirror drive system of the present invention. 2. Swing axis, 3. Galvanometer mirror 4. Swing angle detection mechanism, 5. Micro swing mechanism. Figure 3

Claims (1)

[Claims] 1. In a galvanometer mirror drive system that electromagnetically generates a rocking motion with respect to a rocking axis of a galvanometer mirror, the angle at which the rocking shaft swings due to the electromagnetic force is detected. A micro-oscillation mechanism for micro-oscillating the galvanometer mirror at high speed and high precision is provided coaxially on the pivot axis, and based on the detection output of the above-mentioned swing angle detection mechanism, A high-precision galvanometer mirror drive system, comprising: a control means for compensating for an error angle between the actual swing angle of the swing axis and the control target angle using the minute swing mechanism.