| 摘要 |
<p>PURPOSE:To determine the scanning angle of an optical scanner highly accurately, to achieve the high accuracy of the optical scanner, and to make it possible to discriminate the signs of + or - of the scanning angle. CONSTITUTION:A resonance frequency signal Va (t) generated in a frequency generating device 5 is amplified with a piezoelectric driver 6, and the result is applied on an optical scanner 3. The phases of the deflection angle of the optical scanner 3 and the scanning angle theta (t) of a light beam are delayed by 90 deg. from the resonance frequency signal Va (t). Meanwhile, the resonance frequency signal Va (t) is differentiated with a phase adjuster 7, and the result is outputted as the scanning angle information Vc (t). The phase of the differentiated scanning angle information Vc (t) is delayed by 90 deg. from the phase of the resonance frequency signal Va (t). Thus, the scanning angle information Vc (t) is proportional to the scanning angle theta (t). Therefore, the scanning angle theta(t) can be readily found based on the scanning angle information Vc (t), and + or -of the scanning angle theta (t) can be discriminated at the same time.</p> |
