# US 12,001,010 B2 · Synchronization of microelectromechanical system (MEMS) mirrors

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- Number: US 12,001,010 B2
- Document ID: US12001010B2
- Status: Granted
- Kind: B2
- Application number: 17/690,149
- Filed: 2022-03-09
- Published: 2022-06-23
- Granted: 2024-06-04
- Earliest claimed: 2019-04-05
- Assignees: Infineon Technologies AG
- Applicants: Infineon Technologies AG
- Inventors: Norbert Druml; Philipp Greiner; Boris Kirillov; Ievgeniia Maksymova; Maksym Sladkov; Hendrikus Van Lierop
- Web page: https://patentgrep.com/patent/US12001010B2

## CPC

- G02B 26/0841: {the reflecting element being moved or deformed by electrostatic means}
- G01S 7/4817: {relating to scanning}
- G01S 7/4972: {Alignment of sensor}
- G01S 17/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32)
- G01S 17/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46)
- 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)}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

An oscillator system includes an oscillator structure configured to oscillate about a first axis according to a first oscillation and oscillate about a second axis according to a second oscillation; a first driver configured to drive the first oscillation, detect first zero-crossing events of the first mirror, and generate a first position signal based on the detected first zero-crossing events; a second driver configured to drive the second oscillation, detect second zero-crossing events of the second mirror, and generate a second position signal based on the detected second zero-crossing events; and a synchronization controller configured to receive the first and the second position signals, and synchronize at least one of a phase or a frequency of the second oscillation with at least one of a phase or a frequency of the first oscillation, respectively, based on the first and the second position signals.

## Claims

### Claim 1

An oscillator system, comprising:
an oscillator structure configured to oscillate about a first axis according to a first oscillation and oscillate about a second axis according to a second oscillation;
a first driver configured to drive the first oscillation of the oscillator structure, receive a first measurement signal representative of an entire angular trajectory traversed by the oscillator structure throughout its first oscillation, detect first crossing events of the oscillator structure at which a value of the first measurement signal is equal to a first predefined value that corresponds to a predefined displacement angle of the oscillator structure with respect to the first axis, and generate a first position signal that indicates each of the detected first crossing events with a signal transition;
a second driver configured to drive the second oscillation of the oscillator structure, receive a second measurement signal representative of an entire angular trajectory traversed by the oscillator structure throughout its oscillation, detect second crossing events of the oscillator structure at which a value of the second measurement signal is equal to a second predefined value that corresponds to the predefined displacement angle of the oscillator structure with respect to the second axis, and generate a second position signal that indicates each of the detected second crossing events with a signal transition; and
a synchronization controller configured to receive the first position signal and the second position signal, and synchronize at least one of a phase or a frequency of the first oscillation of the oscillator structure with at least one of a phase or a frequency of the second oscillation of the oscillator structure, respectively, based on the first position signal and the second position signal.

### Claim 2 (depends on 1)

The oscillator system of claim 1, wherein the synchronization controller comprises:
a phase frequency detector configured to receive the first position signal and the second position signal and generate a control signal based thereon; and
a loop filter configured to generate an actuation value based on the control signal, and transmit the actuation value to the second driver.

### Claim 3 (depends on 2)

The oscillator system of claim 2, wherein the second driver is configured to receive the actuation value and control an actuation of the oscillator structure about the second axis based on the actuation value such that the at least one of the phase or the frequency of the first oscillation of the oscillator structure is synchronized with the at least one of the phase or the frequency of the second oscillation of the oscillator structure, respectively.

### Claim 4 (depends on 3)

The oscillator system of claim 3, wherein the frequency of the oscillator structure about the first axis has a predefined fractional relationship with the frequency of the oscillator structure about the second axis, wherein the predefined fractional relationship is not equal to 1.

### Claim 5 (depends on 4)

The oscillator system of claim 4, wherein the synchronization controller further comprises:
a first divider configured to divide a frequency of the first position signal by a first integer to generate a frequency divided first position signal; and
a second divider configured to divide a frequency of the second position signal by a second integer to generate a frequency divided second position signal, wherein a ratio of the first integer and the second integer negate the predefined fractional relationship in the first position signal and the second position signal,
wherein the phase frequency detector is configured to receive the frequency divided first position signal as the first position signal and receive the frequency divided second position signal as the second position signal.

### Claim 6 (depends on 1)

The oscillator system of claim 1, further comprising:
a phase detector configured to receive the first position signal and the second position signal and measure a phase difference therebetween; and
a Lissajous frame start detector configured to receive the measured phase difference and determine a start of a Lissajous frame based on the measured phase difference.

### Claim 7 (depends on 6)

The oscillator system of claim 6, wherein the frequency of the oscillator structure about the first axis has a predefined fractional relationship with the frequency of the oscillator structure about the second axis, wherein the predefined fractional relationship is not equal to 1, and the synchronization controller further comprises:
a first divider configured to divide a frequency of the first position signal by a first integer to generate a frequency divided first position signal; and
a second divider configured to divide a frequency of the second position signal by a second integer to generate a frequency divided second position signal, wherein a ratio of the first integer and the second integer negates a predefined fractional relationship between the first position signal and the second position signal,
wherein the phase detector is configured to receive the frequency divided first position signal as the first position signal and receive the frequency divided second position signal as the second position signal.

### Claim 8 (depends on 1)

The oscillator system of claim 1, wherein:
the first driver is configured to trigger a change in the first position signal at each of the first crossing events such that the first position signal indicates the frequency and a phase of the first oscillation of the oscillator structure, and
the second driver is configured to trigger a change in the second position signal at each of the second crossing events such that the second position signal indicates the frequency and a phase of the second oscillation of the oscillator structure.

### Claim 9 (depends on 1)

The oscillator system of claim 1, wherein the oscillator structure is a microelectromechanical system (MEMS) mirror.

### Claim 10 (depends on 1)

The oscillator system of claim 1, wherein the oscillator structure is a non-linear resonator.

### Claim 11 (depends on 1)

The oscillator system of claim 1, wherein the predefined displacement angle is associated with a non-zero velocity of the oscillator structure.

### Claim 12

A method of synchronizing a first oscillation of an oscillator structure about a first axis with a second oscillation of the oscillator structure about a second axis, the method comprising:
driving the first oscillation of the oscillator structure about a first axis;
driving the second oscillation of the oscillator structure about a second axis;
monitoring a first measurement signal representative of an entire angular trajectory traversed by the oscillator structure throughout its first oscillation;
detecting first crossing events of the oscillator structure at which a value of the first measurement signal is equal to a predefined value that corresponds to a predefined displacement angle of the oscillator structure with respect to the first axis;
generating a first position signal that indicates each of the detected first crossing events with a signal transition;
monitoring a second measurement signal representative of an entire angular trajectory traversed by the oscillator structure throughout its second oscillation;
detecting second crossing events of the oscillator structure at which a value of the second measurement signal is equal to a second predefined value that corresponds to the predefined displacement angle of the oscillator structure with respect to the second axis;
generating a second position signal that indicates each of the detected second crossing events with a signal transition; and
synchronizing at least one of a phase or a frequency of the first oscillation of the oscillator structure with at least one of a phase or a frequency of the second oscillation of the oscillator structure, respectively, based on the first position signal and the second position signal.