# US 11,029,509 B2 · Optical module, electronic device, and driving method

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- Number: US 11,029,509 B2
- Document ID: US11029509B2
- Status: Granted
- Kind: B2
- Application number: 16/788,602
- Filed: 2020-02-12
- Published: 2020-06-11
- Granted: 2021-06-08
- Earliest claimed: 2012-09-12
- Assignees: Seiko Epson Corporation
- Applicants: Seiko Epson Corporation
- Inventors: Tomonori Matsushita; Nozomu Hirokubo
- Web page: https://patentgrep.com/patent/US11029509B2

## CPC

- G02B 26/001: {based on interference in an adjustable optical cavity (interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26)}
- G01J 3/0264: {Electrical interface; User interface}
- G01J 3/027: {Control of working procedures of a spectrometer; Failure detection; Bandwidth calculation}
- G01J 3/0291: {Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements}
- G01J 3/06: Scanning arrangements {arrangements for order-selection}
- G01J 3/10: Arrangements of light sources specially adapted for spectrometry or colorimetry
- G01J 3/26: using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
- G01J 3/28: Investigating the spectrum (using colour filters G01J3/51)
- G01J 3/2823: {Imaging spectrometer}
- G01J 3/32: Investigating bands of a spectrum in sequence by a single detector
- G01J 3/42: Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry (beam switching arrangements G01J3/08)
- G01J 3/50: using electric radiation detectors
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)

## Abstract

An optical module includes a wavelength variable interference filter having a fixed reflective film, a movable reflective film which faces the fixed reflective film with a gap between reflective films interposed therebetween, and an electrostatic actuator that changes the gap between reflective films, and a gap control unit that controls the electrostatic actuator. The gap control unit controls the electrostatic actuator on the basis of an order which is set in accordance with a wavelength to be measured, and changes the gap between the reflective films.

## Claims

### Claim 1

A driving method of a wavelength variable interference filter, the wavelength variable interference filter including a pair of mirrors having a gap between the mirrors, the pair of the mirrors being configured to move with respect to each other to vary the gap; an actuator configured to move one of the pair of the mirrors to set the gap between the mirrors according to a voltage applied thereto, so that the wavelength variable interference filter transmits a first wavelength of light corresponding to the gap; and a pair of electrodes configured to detect a capacitance formed therebetween according to the gap between the pair of the mirrors, wherein the gap between the pair of mirror is (i) a first distance when no voltage is applied to the actuator, (ii) a second distance when a first voltage is applied to the actuator where the second distance is less than the first distance, and (iii) a third distance when a second voltage is applied to the actuator where the third distance is greater than the second distance and the second voltage is less than the first voltage, the driving method comprising:
detecting, by using the pair of electrodes, the first distance when no voltage is applied to the actuator;
receiving wavelength data that specifies a second wavelength of light;
retrieving, from a memory, gap data that represents different distances of the gap at which the wavelength variable interference filter transmits the second wavelength of light, the different distances of the gap corresponding to respective different orders of light transmission of the wavelength variable interference filter;
selecting a fourth distance from among the different distances of the gap, so that the selected fourth distance is equal to or less than the detected first distance and equal to or greater than the second distance;
retrieving, from the memory, voltage data corresponding to the selected fourth distance; and
applying, to the actuator, a third voltage based on the retrieved voltage data to set the gap of the pair of the mirrors to be the selected fourth distance, so that the wavelength variable interference filter transmits the second wavelength of light.

### Claim 2 (depends on 1)

The driving method of wavelength variable interference filter according to claim 1, wherein the wavelength variable interference filter is a variable Fabry-Perot etalon.

### Claim 3

A non-transitory computer readable medium that stores instructions for driving a wavelength variable interference filter, the wavelength variable interference filter including a pair of mirrors having a gap between the mirrors, the pair of the mirrors being configured to move with respect to each other to vary the gap; an actuator configured to move one of the pair of the mirrors to set the gap between the mirrors according to a voltage applied thereto, so that the wavelength variable interference filter transmits a first wavelength of light corresponding to the gap; and a pair of electrodes configured to detect a capacitance formed therebetween according to the gap between the pair of the mirrors, wherein the gap between the pair of mirrors is (i) a first distance when no voltage is applied to the actuator, (ii) a second distance when a first voltage is applied to the actuator where the second distance is less than the first distance, and (iii) a third distance when a second voltage is applied to the actuator where the third distance is greater than the second distance and the second voltage is less than the first voltage, the instructions causing one or more processors to:
detect, by using the pair of electrodes, the first distance when no voltage is applied to the actuator;
receive wavelength data that specifies a second wavelength of light;
retrieve, from a memory, gap data that represents different distances of the gap at which the wavelength variable interference filter transmits the second wavelength of light, the different distances of the gap corresponding to respective different orders of light transmission of the wavelength variable interference filter;
select a fourth distance from among the different distances of the gap, so that the selected fourth distance is equal to or less than the detected first distance and equal to or greater than the second distance;
retrieve, from the memory, voltage data corresponding to the selected fourth distance; and
apply, to the actuator, a third voltage based on the retrieved voltage data to set the gap of the pair of the mirrors to be the selected fourth distance, so that the wavelength variable interference filter transmits the second wavelength of light.

### Claim 4 (depends on 3)

The non-transitory computer readable medium according to claim 3, wherein the wavelength variable interference filter is a variable Fabry-Perot etalon.