Optical scanning apparatus and method of controlling optical scanning apparatus

Patent metadata

Field	Value
Publication number	US-11054634-B2
Application number	US-201916671427-A
Country	US
Kind code	B2
Filing date	Nov 1, 2019
Priority date	Dec 28, 2018
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

An optical scanning apparatus that oscillates a mirror in at least one direction, includes a mirror driving circuit including a digital-to-analog converter and an amplifier and generating a pair of driving signals for driving the mirror based on digital driving waveform data, a reference waveform data generator generating a reference waveform data, and an offset setting circuit setting an offset value of the reference waveform data, based on a dead band of the amplifier and a periodic integral non-linearity error of the digital-to-analog converter, to generate the driving waveform data.

First claim

What is claimed is:

1. An optical scanning apparatus that oscillates a mirror in at least one direction, comprising:
a mirror driving circuit, including a digital-to-analog converter and an amplifier, configured to generate a pair of driving signals for driving the mirror based on digital driving waveform data;
a reference waveform data generator configured to generate a reference waveform data; and
an offset setting circuit configured to set an offset value of the reference waveform data, based on a dead band of the amplifier and a periodic integral non-linearity error of the digital-to-analog converter, to generate a driving waveform data.

2. The optical scanning apparatus as claimed in claim 1 , wherein
the pair of driving signals include a first driving signal, and a second driving signal having a potential inverted with respect to an intermediate potential of the first driving signal, and
the mirror driving circuit drives the mirror according to a potential difference between the first driving signal and the second driving signal.

3. The optical scanning apparatus as claimed in claim 2 , wherein the offset setting circuit sets the offset value to a value, that is larger than an upper limit value of a dead zone on a ground potential side of the amplifier, and matches a phase of the integral non-linearity error superimposed on the first driving signal and a phase of the integral non-linearity error superimposed on the second driving signal.

4. The optical scanning apparatus as claimed in claim 3 , wherein
the first driving signal and the second driving signal are sawtooth waves, and
the mirror driving circuit causes a non-resonant oscillation of the mirror.

5. The optical scanning apparatus as claimed in claim 4 , further comprising:
a deflection angle sensor configured to detect a position of the mirror along the one direction; and
a gain setting circuit configured to set a gain corresponding to amplitudes of the first driving signal and the second driving signal, based on a detection value of the deflection angle sensor.

6. The optical scanning apparatus as claimed in claim 5 , wherein the offset setting circuit sets the offset value to a minimum value of D satisfying a formula D=(n×M+M/2−G)/2 and a relationship D>Dth, where n denotes a positive integer, M denotes a period of a change of the integral non-linearity error, G denotes a gain of the driving waveform data, and Dth denotes an upper limit value of the dead zone on the ground potential side of the amplifier.

7. A method of controlling an optical scanning apparatus that includes a mirror driving circuit, including a digital-to-analog converter and an amplifier, and configured to generate a pair of driving signals for driving a mirror based on digital driving waveform data, and oscillate the mirror in at least one direction, the method comprising:
generating a reference waveform data; and
setting an offset value of the reference waveform data, based on a dead band of the amplifier and a periodic integral non-linearity error of the digital-to-analog converter, to generate a driving waveform data.

8. The method of controlling the optical scanning apparatus as claimed in claim 7 , wherein the generating and the setting are performed by a system controller included in the optical scanning apparatus.

9. The method of controlling the optical scanning apparatus as claimed in claim 8 , wherein the generating and the setting are performed by a processor of the system controller, configured to execute a program stored in a memory of the system controller.

10. The method of controlling the optical scanning apparatus as claimed in claim 8 , wherein the pair of driving signals include a first driving signal, and a second driving signal having a potential inverted with respect to an intermediate potential of the first driving signal, and further comprising:
driving the mirror, by a mirror driving circuit included in the optical scanning apparatus, according to a potential difference between the first driving signal and the second driving signal.

11. The method of controlling the optical scanning apparatus as claimed in claim 10 , wherein the setting the offset value sets the offset value to a value, that is larger than an upper limit value of a dead zone on a ground potential side of the amplifier, and matches a phase of the integral non-linearity error superimposed on the first driving signal and a phase of the integral non-linearity error superimposed on the second driving signal.

12. The method of controlling the optical scanning apparatus as claimed in claim 11 , wherein
the first driving signal and the second driving signal are sawtooth waves, and
the driving causes a non-resonant oscillation of the mirror.

13. The method of controlling the optical scanning apparatus as claimed in claim 12 , further comprising:
detecting, by a deflection angle sensor included in the optical canning apparatus, a position of the mirror along the one direction; and
setting, by the system controller, a gain corresponding to amplitudes of the first driving signal and the second driving signal, based on a detection value of the deflection angle sensor.

14. The method of controlling the optical scanning apparatus as claimed in claim 13 , wherein the setting the offset value sets the offset value to a minimum value of D satisfying a formula D=(n×M+M/2−G)/2 and a relationship D>Dth, where n denotes a positive integer, M denotes a period of a change of the integral non-linearity error, G denotes a gain of the driving waveform data, and Dth denotes an upper limit value of the dead zone on the ground potential side of the amplifier.

Assignees

• Kimura Yuji
• Hibiya Riichiro
• Mitsumi Electric Co Ltd

Inventors

• Kimura Yuji
• Hibiya Riichiro

Classifications

• G02B26/0858 Primary

  the reflecting means being moved or deformed by piezoelectric means · CPC title

• G02B26/101 Primary

  with both horizontal and vertical deflecting means, e.g. raster or XY scanners (colour television using laser beams scanning a display screen H04N9/3129) · CPC title

• G02B26/105

  with one or more pivoting mirrors or galvano-mirrors (G02B26/101 takes precedence) · CPC title