JPS62133417A - Method of inspecting dynamic characteristic of vibration mirror - Google Patents

Abstract

PURPOSE:To easily readjust a control system even when a scanner mechanism is replaced by practically driving the scanner mechanism at frequency close to its resonance frequency to obtain the amplitude gain and phase frequency response of the whole scanner mechanism. CONSTITUTION:The scanner mechanism 12 is driven by drivin current generated from a scanning mirror driving voltage generator 10 and amplified by a power amplifier 11 and the movement of the scanning mirror driven by the current is detected by an angular amplitude detector 33. The voltage is compared with a voltage corresponding to the driving current by a two-quadrant oscilloscope 4 to find out the amplitude gain and phase frequency characteristics. The voltage generated from the generator 10 is set up to a sine wave with frequency close to the resonance frequency of twisted oscillation regulated by the inertia of the scanning mirror and the tortion elasticity of a tortion spring supporting the scanning mirror and its amplitude is modulated by a signal with frequency lower than that of the sine wave to obtain the amplitude gain response G and the phase change phi. Since the G and phi are previously calculated, the constant of a necessary circuit element can be easily determined even if the scanner mechanism is replaced.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figure 5) Problems to be solved by the invention Means for solving the problems (Figure 1) Working examples (Figure 1) (Figures 2 to 4) Effects of the invention [Summary] In a scanner mechanism used in a scanning system that optically scans a field of view by vibrating a scanning mirror at a constant amplitude, the scanner mechanism is actually operated at a frequency close to its resonant frequency. to obtain the amplitude gain and phase frequency response of the entire scanner mechanism.

[Industrial application field]

The present invention relates to an optical scanning mechanism for an image sensing device, and more particularly to a scanner mechanism used in a scanning system that optically scans a field of view using a vibrating mirror, and relates to an optical scanning mechanism for measuring the characteristics of the scanner mechanism. This provides a method for testing mirror dynamic properties.

[Conventional technology]

In devices such as infrared image detection devices where it is difficult to obtain two-dimensional sensors, two-dimensional images are obtained using sensors arranged in a row. In order to obtain a two-dimensional image using sensors arranged in a row, it is necessary to scan the entire field of view and sequentially obtain signals of images of the field of view. Scanning typically uses a vibrating mirror.

FIG. 5 is a diagram showing such a scanner mechanism. In FIG. 0, 30 is a scanning mirror, which is fixed to a torsion bar 31 provided on a scanning mirror gimbal 35. The torsion bar 31 has one end connected to the scanning mirror gimbal 35.
The other end is pivotally supported via a bearing 32. A scanning mirror swing amplitude detector 33 is provided on the bearing 32 side. Scanning mirror swingable amplitude detector 3
For example, a potentiometer or the like can be used for 3, but any other device may be used as long as it can detect the swingable amplitude of the torsion bar 31. A suction arm 34 having at least a head made of a magnetic material is fixed to the torsion bar 31. 2 & 1 each consisting of two solenoids, facing the head of the torsion bar 31.
1 solenoid is provided. solenoid 36.3
6' and a set consisting of solenoids 37 and 37'. Solenoid 36, 36' and Solenoid 37
．． By passing excitation current alternately through 37',
The suction arm 34 is connected to the solenoid 36, 36' and the solenoid 3.
7. Aspirate at 37'. This causes the suction arm 34 to vibrate, and therefore the torsion bar 31 and the torsion bar 3
It is possible to vibrate the scanning mirror which is fixed at 1. Since one end of the torsion bar 31 is fixed to the scanning mirror gimbal 35, the scanning mirror undergoes torsional vibration defined by the torsional elasticity of the torsion bar and the inertia of the scanning mirror.

Therefore, a two-dimensional image signal can be obtained by incorporating this scanning mirror into a part of the optical system, placing a sensor at the focal point, and vibrating the scanning mirror.

In this case, in order to accurately obtain a two-dimensional image to be detected,
The scanning range for each scan needs to be constant, and therefore the amplitude of vibration needs to be constant.

[Problem that the invention seeks to solve]

By the way, in order to keep the amplitude of vibration constant, it is necessary to configure an automatic control system, but since there was no method to measure the dynamic characteristics of the scanner mechanism, it was necessary to construct an automatic control system with the actual control loop formed. The problem was that the circuit and m-structure had to be adjusted empirically. Moreover, if either one of the scanner mechanisms has failed or the control circuit board has failed, and it becomes necessary to combine the scanner mechanism with another control circuit board, extensive readjustment will be required and the unit will not be compatible. This has the problem of being a major hindrance to sexual realization.

An object of the present invention was to solve the above-mentioned problems, and to provide a control system for a scanner mechanism used in a closed-loop control scanner system that controls the vibration amplitude of a scanning mirror at a constant level by changing the current. The present invention provides a method for examining the frequency response of amplitude gain and phase, which are characteristics as elements of .

[Means for solving problems]

In order to solve the above-mentioned problems, in the present invention, as shown in FIG. 1, the scanner mechanism 12 is driven by a drive current generated by a scanning mirror drive voltage generator 10 and amplified by a power amplifier 11. The scanning mirror swing amplitude detector 3 detects the movement of the scanning mirror driven by this current.
3, and this voltage is compared with the voltage corresponding to the drive current using a two-quadrant oscilloscope to obtain frequency characteristics of amplitude gain and phase. Scanning mirror drive voltage generator power? These voltages are sinusoidal waves with a frequency close to the resonant frequency of torsional vibration defined by the inertia of the scanning mirror and the torsional elasticity of the torsion bar supporting the scanning mirror, and also at a frequency lower than that. Amplitude modulation is performed using the signal.

Thereby, the amplitude gain response G and phase change φ are determined.

[Effect]

As described above, the amplitude gain response G and phase change ψ of a specific scanner mechanism required when configuring a closed-loop control system can be obtained in advance, so even if the scanner mechanism is replaced, G and φ have been determined in advance. Constants of necessary circuit elements can be easily determined.

〔Example〕

The present invention will be described in detail with reference to FIG. The same parts as those shown in the principle diagram of FIG. 1 are given the same figure numbers, so detailed explanations will be omitted.

In this embodiment, the scanning mirror drive voltage generator lO includes a scanning mirror vibration frequency oscillator 21 that oscillates vibrations at a frequency close to the resonant frequency of the scanning mirror, and an amplitude modulation voltage generator 22.
and a multiplier 23 that multiplies the outputs of the oscillators 21 and 22.
It is included.

Assume that the scanning mirror vibration frequency oscillator 21 generates a pulse of, for example, 60 Hz and a duty ratio of 50%. At this time, the scanning mirror vibration frequency oscillator 21 generates a DC-offset voltage for modulation from the amplitude modulation voltage generator 22 at a frequency sufficiently lower than 6011z, for example, a fraction of a 111z to several Hz. , that is, the 6011z signal, is modulated by a DC-offset signal from the amplitude modulation voltage generator 22 with a sufficiently lower frequency to obtain an amplitude-modulated 6011z pulse train (al. This is passed through the low-pass filter 24 From its output end, an amplitude-modulated 60 Ilz sine wave signal (bl is obtained. The signal Tbl is amplified and voltage-current converted by a power amplifier), and one of the outputs is sent to the scanner mechanism 12. Another of its outputs is input to channel 1 of the two-quadrant oscilloscope.Scanner mechanism 12
As explained in FIG. 5, there is a solenoid 2&[I, so the scanning mirror is vibrated by applying human power to this solenoid. The amplitude of the scanning mirror swing angle changes with a certain gain and phase with respect to the drive current. A mirror swingable amplitude detector 13 scans this swingable amplitude.
and adds this to channel 2 of the two-quadrant oscilloscope 14. In this way, the detection signal from the detector 13 and the drive current waveform from the power amplifier 11 are observed with a two-quadrant oscilloscope. That is, from the envelope of the drive current waveform created by the output of the power amplifier 11 input to channel 1, the difference Δ■ between the highest and lowest parts is determined, and the difference Δ■ between the highest and lowest parts is calculated.
The amplitude Δθ is determined from the output of the detector 13, and from this, the gain G−Δθ/Δ■ is determined. Also, find the delay Tdelay between the CHI signal and the CH2 signal, and calculate the phase φ-360XTdelay /To (To
:Period). These G and φ are characteristics that the scanner mechanism has, and by knowing these G and φ, a control system can be set up in advance.

FIG. 3 shows a scanner system that automatically controls the scanner mechanism shown in FIG. 5 using the dynamic characteristics obtained by the present invention.
Shows a system diagram. In the figure, 42 is a scanner mechanism, which includes a scanning mirror 30, a solenoid 44, and a scanning mirror swing amplitude detector 33.

Solenoid 44 is 36.36 as detailed in FIG.
′ and 2&[I of 37.37′. 41 is a scanner control circuit, which includes a scanning mirror vibration frequency oscillator 21, a multiplier 23, a low-pass filter 24, an amplifier 11. It includes an amplitude control voltage generator 43.

This operation will be explained with reference to the operation waveform diagram in FIG.

A voltage (A) for vibrating the scanning mirror 30 is generated by the scanning mirror vibration frequency oscillator 21 .

The zero multiplier 23, which supplies this output (A) to the low-pass filter 24 via the multiplier 23, is supplied with an output (C) from an amplitude control voltage generator 43, which will be described later. C) modulates the output (A). The output (D) of the multiplier 23 is modulated by the output (C).

This output (D) is made into a sine wave output (F) by the low-pass filter 24, amplified via the power amplifier 11, and then connected to the solenoid pair 36.
) and 37.37' (this is called ODD) in a half-wave rectified form. As a result, the scanning mirror 30 vibrates as shown by the swing angle.

This vibration is detected by the scanning mirror swing amplitude detector 33. This output is expressed as a voltage according to the difference from the specified amplitude.
This is obtained as the scanning mirror swing amplitude detector output shown in (B). Adding this output (B) to the amplitude control voltage generator 43,
An output (C) is obtained from this amplitude control voltage generator 43. By applying this output (C) to the multiplier 23, the vibration of the scanning mirror 30 is fed back and the amplitude of the scanning mirror 30 is kept constant.

Note that the purpose of driving at a frequency close to the resonance frequency is to increase driving efficiency.

(Effects of the Invention) According to the present invention, it is possible to obtain the frequency response of the amplitude gain and phase of the scanner mechanism necessary when configuring an automatic control system using a relatively simple method, and thus the automatic control system can be easily constructed. Can be assembled.

Moreover, by measuring the characteristics of each scanner mechanism, the control system can be easily readjusted even when the scanner mechanism is replaced.

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a diagram showing an embodiment of the invention, Fig. 3 is a scanner system diagram, Fig. 4 is an operation waveform diagram of the scanner system, and Fig. 5 is a scanner mechanism. It is a diagram. 10--Scanning mirror drive voltage generator 11--Power amplifier 12-Scanner mechanism 14--
-2-quadrant oscilloscope 30...-scanning tJi 31--torsion bar 33--scanning mirror swingable amplitude detector 36.
36', 37.37' - Solenoid 34 - Suction arm 35 - Scanning mirror gimbal G = correction

Claims (1)

[Claims] In a scanner mechanism used in a scanning system that optically scans a field of view by vibrating a scanning mirror with a constant amplitude, the scanner mechanism is configured to vibrate with a sine wave having a frequency close to its resonant frequency and a frequency lower than that. At the same time, the swing angle amplitude of the scanning mirror of the scanner mechanism is detected, and by comparing this detection result with the drive current amplitude, the frequency response of the amplitude gain and phase of the scanner mechanism is determined. A vibration mirror dynamic characteristic inspection method characterized by obtaining the following characteristics.