# US 12,007,556 B2 · Light deflection device

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- Number: US 12,007,556 B2
- Document ID: US12007556B2
- Status: Granted
- Kind: B2
- Application number: 17/226,242
- Filed: 2021-04-09
- Published: 2021-10-28
- Granted: 2024-06-11
- Earliest claimed: 2020-04-22
- Assignees: Stanley Electric Co., Ltd.
- Applicants: Stanley Electric Co., Ltd.
- Inventors: Atsuhiko Chikaoka
- Web page: https://patentgrep.com/patent/US12007556B2

## CPC

- H10N 30/20: with electrical input and mechanical output, e.g. functioning as actuators or vibrators
- B81B 3/0021: {Transducers for transforming electrical into mechanical energy or vice versa (dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00)}
- B81B 3/0045: {Improve properties related to angular swinging, e.g. control resonance frequency}
- B81B 3/0062: {Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension}
- B81B 7/008: {MEMS characterised by an electronic circuit specially adapted for controlling or driving the same (B81B7/0087 takes precedence; arrangements for starting, regulating, braking, or otherwise controlling an actuator H02N; control arrangements or circuits for visual indicators G09G3/00)}
- B81B 7/02: containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] (B81B7/04 takes precedence)
- G02B 26/0858: {the reflecting means being moved or deformed by piezoelectric means}
- G02B 26/101: {with both horizontal and vertical deflecting means, e.g. raster or XY scanners (colour television using laser beams scanning a display screen H04N9/3129)}
- B81B 2201/042: Micromirrors, not used as optical switches
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An light deflection device includes an light deflector having first and second piezoelectric actuators which cause a mirror unit to reciprocatingly turn around a resonant axis and a non-resonant axis, respectively, a drive unit which supplies first and second drive voltages, a swing angle fluctuation width detection unit which detects a first swing angle fluctuation width of the mirror unit around the resonant axis, a sensitivity equivalent value detection unit which detects a sensitivity equivalent value on the basis of a detected value of a second drive voltage fluctuation width and a detected value of the first swing angle fluctuation width, and a determination unit which determines whether a non-resonant axis side swing state of the mirror unit around the non-resonant axis is normal on the basis of a detected value of the sensitivity equivalent value.

## Claims

### Claim 1

An light deflection device comprising:
an light deflector having a mirror unit, a first piezoelectric actuator configured to cause the mirror unit to reciprocatingly turn around a first axis resonantly, and a second piezoelectric actuator configured to cause the mirror unit to reciprocatingly turn around a second axis non-resonantly, the second axis being in an intersecting relationship with the first axis;
a drive unit configured to supply a first drive voltage and a second drive voltage to the first piezoelectric actuator and the second piezoelectric actuator, respectively, of the light deflector;
a voltage fluctuation width detection unit configured to detect a second drive voltage fluctuation width;
a swing angle fluctuation width detection unit configured to detect a first swing angle fluctuation width as a fluctuation width of a swing angle of the mirror unit around the first axis;
a sensitivity equivalent value detection unit configured to detect a sensitivity equivalent value on the basis of a detected value of the second drive voltage fluctuation width and a detected value of the first swing angle fluctuation width, the sensitivity equivalent value being a ratio of the first swing angle fluctuation width to the second drive voltage fluctuation width; and
a determination unit configured to determine whether a second axis side swing state of the mirror unit around the second axis is normal, on the basis of a detected value of the sensitivity equivalent value.

### Claim 2 (depends on 1)

The light deflection device according to claim 1, wherein
the determination unit includes
a data holding unit which holds data that defines a rated relationship between the second drive voltage fluctuation width and a rated value of the sensitivity equivalent value, and
a calculation determination unit configured to calculate a corresponding rated value of the sensitivity equivalent value corresponding to a detected value of the second drive voltage fluctuation width on the basis of the rated relationship, and determine the second axis side swing state on the basis of a contrast between the detected value of the sensitivity equivalent value and the corresponding rated value of the sensitivity equivalent value.

### Claim 3 (depends on 2)

The light deflection device according to claim 2, wherein
with first and second conditions being set as conditions that cause the light deflector to operate with mutually different fluctuation widths Vw1 and Vw2, respectively, of the second drive voltage fluctuation width,
the calculation determination unit performs the contrast, using a detected value Sd1 of the sensitivity equivalent value under the first condition and a corresponding rated value Sr1 corresponding to the fluctuation width Vw1, and a detected value Sd2 of the sensitivity equivalent value under the second condition and a corresponding rated value Sr2 corresponding to the fluctuation width Vw2, by contrasting a relative relationship between the detected value Sd1 and the detected value Sd2 with a relative relationship between the corresponding rated value Sr1 and the corresponding rated value Sr2.

### Claim 4 (depends on 3)

The light deflection device according to claim 3, wherein
the calculation determination unit performs the contrast between the relative relationships by contrasting a ratio of Sd1 to Sd2 with a ratio of Sr1 to Sr2.

### Claim 5 (depends on 3)

The light deflection device according to claim 3, wherein
the calculation determination unit performs the contrast between the relative relationships by contrasting a difference between Sd1 and Sd2 with a difference between Sr1 and Sr2.

### Claim 6 (depends on 3)

The light deflection device according to claim 3, wherein
the fluctuation width Vw1 under the first condition is a non-customizable second axis side voltage fluctuation width at the time of startup of the light deflector, and
the fluctuation width Vw2 under the second condition is a customizable second axis side voltage fluctuation width changed at a first change after the startup.

### Claim 7 (depends on 3)

The light deflection device according to claim 3, wherein
the fluctuation width Vw1 under the first condition and the fluctuation width Vw2 under the second condition are the second drive voltage fluctuation widths before and after the second drive voltage fluctuation width is changed while a first drive voltage fluctuation width as a fluctuation width of the first drive voltage is maintained.

### Claim 8 (depends on 1)

The light deflection device according to claim 1, wherein
the determination unit determines that the swing angle fluctuation width detection unit is in a failure state in the case where the detected value of the sensitivity equivalent value has changed by more than a predetermined threshold value during a period in which the second drive voltage fluctuation width is kept constant.