阅读说明：本技术 光扫描装置及其控制方法 (Optical scanning device and control method thereof ) 是由 伊藤恭彦 绀野伸显 平田善明 于 2018-12-17 设计创作，主要内容包括：提供即使使扫描范围变化也能够将空间分辨率保持成恒定的光扫描装置(100)。光扫描装置(100)具备：光源(101),发出光；扫描镜(106),为利用反射面反射从光源入射的光的扫描镜(106),能够绕通过反射面内的第1轴以及与第1轴正交且通过反射面内的第2轴分别独立地振动；以及控制部(103),控制扫描镜(106)的绕第1轴振动的第1频率以及第1振幅以及绕第2轴振动的第2频率以及第2振幅,扫描被扫描镜(106)的反射面反射的光。控制部(103)根据副扫描方向的最大扫描角来控制第2频率。(Provided is an optical scanning device (100) capable of maintaining a spatial resolution constant even when a scanning range is changed. An optical scanning device (100) is provided with: a light source (101) that emits light; a scanning mirror (106) that reflects light incident from the light source by a reflection surface, and that can independently oscillate about a 1 st axis passing through the reflection surface and a 2 nd axis orthogonal to the 1 st axis and passing through the reflection surface; and a control unit (103) that controls the 1 st frequency and the 1 st amplitude of the scanning mirror (106) that oscillates about the 1 st axis and the 2 nd frequency and the 2 nd amplitude of the scanning mirror (106) that oscillates about the 2 nd axis, and scans the light reflected by the reflection surface of the scanning mirror (106). A control unit (103) controls the 2 nd frequency according to the maximum scanning angle in the sub-scanning direction.)

1. An optical scanning device includes:

a light source emitting light;

a scanning mirror that reflects light incident from the light source by a reflection surface, and that is capable of independently oscillating about a 1 st axis passing through the reflection surface and a 2 nd axis that is orthogonal to the 1 st axis and passes through the reflection surface; and

a control unit for controlling the 1 st frequency and the 1 st amplitude of the oscillation of the scanning mirror about the 1 st axis and the 2 nd frequency and the 2 nd amplitude of the oscillation about the 2 nd axis to scan the light reflected by the reflecting surface of the scanning mirror,

the optical scanning device scans a scanning range defined by a maximum scanning angle in a main scanning direction and a maximum scanning angle in a sub-scanning direction, the maximum scanning angle in the main scanning direction varying according to the 1 st amplitude, the sub-scanning direction being orthogonal to the main scanning direction and the maximum scanning angle in the sub-scanning direction varying according to the 2 nd amplitude, with light emitted from the light source,

the control unit controls the 2 nd frequency according to a maximum scanning angle in the sub-scanning direction.

2. The optical scanning device according to claim 1,

the control section controls the 2 nd frequency, and controls the 2 nd amplitude in accordance with the 2 nd frequency, thereby controlling the maximum scanning angle in the sub-scanning direction.

3. The optical scanning device according to claim 1 or 2,

the control unit controls the 2 nd frequency or the maximum scanning angle in the sub-scanning direction so that a product of the 2 nd frequency and the maximum scanning angle in the sub-scanning direction becomes constant.

4. The optical scanning device according to claim 3,

the product of the 2 nd frequency and the maximum scanning angle in the sub-scanning direction is equal to the product of the 1 st frequency and the spatial resolution, which is the angular interval between adjacent main scanning lines.

5. The optical scanning device according to any one of claims 1 to 4,

so that pass through the 1 st axle with the nodical the scanning mirror the normal line of plane of reflection go on with the mode of the angular motion that nodical is the center, adjust the winding of scanning mirror the phase place of 1 st axle vibration with wind the phase place of 2 nd axle vibration.

6. The optical scanning device according to any one of claims 1 to 5,

the maximum scan angle of the sub-scan direction is 360^°。

7. The optical scanning device according to any one of claims 1 to 6,

the optical scanning device further includes a scanning angle conversion unit that further reflects the light reflected by the scanning mirror.

8. The optical scanning device according to any one of claims 1 to 7,

the control unit sets the value of the 1 st frequency to a value equal to a resonance frequency of the scan mirror about the 1 st axis.

9. The optical scanning device according to any one of claims 1 to 8,

the scanning mirror is a MEMS scanning mirror.

10. The optical scanning device according to any one of claims 1 to 9,

the scanning mirror is a piezoelectric driving type scanning mirror.

11. The optical scanning device according to any one of claims 1 to 10,

the optical scanning device further includes an inertial force sensor that detects an inertial force applied to the inside of the optical scanning device,

the control unit controls the 2 nd frequency or the maximum scanning angle in the sub-scanning direction based on the inertial force detected by the inertial force sensor.

12. The optical scanning device according to claim 11,

the inertial force sensor is an acceleration sensor that detects acceleration of the optical scanning device.

13. The optical scanning device according to claim 12,

the control unit controls the 2 nd frequency or the maximum scanning angle in the sub-scanning direction to be smaller as the acceleration detected by the acceleration sensor is larger.

14. The optical scanning device according to claim 11,

the inertial force sensor is an angular velocity sensor that detects an angular velocity of the optical scanning device.

15. The optical scanning device according to claim 14,

the control unit controls the 2 nd frequency or the maximum scanning angle in the sub-scanning direction to be larger as an absolute value of the angular velocity detected by the angular velocity sensor is larger.

16. The optical scanning device according to any one of claims 11 to 15,

the inertial force sensor is a MEMS sensor.

17. The optical scanning device according to any one of claims 11 to 16,

the inertial force sensor and the scanning mirror are configured on the same substrate.

18. The optical scanning device according to any one of claims 1 to 17,

the optical scanning device further includes a speed sensor for detecting a speed of the optical scanning device,

the control unit controls the 2 nd frequency or the maximum scanning angle in the sub-scanning direction based on the speed detected by the speed sensor.

19. A method of controlling the optical scanning apparatus of any one of claims 11 to 17, comprising:

a step of detecting the inertial force by the inertial force sensor; and

a step of controlling the 2 nd amplitude of the scanning mirror in accordance with the detected inertial force, thereby controlling a maximum scanning angle in the sub-scanning direction.

Technical Field

The present invention relates to an optical scanning device and a control method thereof, and more particularly, to an optical scanning device capable of performing wide-range scanning with high spatial resolution and a control method thereof.

Background

An optical scanning device that emits light to the surroundings and scans the light is used as a distance measuring device that measures the distance to an object located around the device, by being used together with a light receiving unit that receives the light. For example, patent document 1 discloses an optical flying type distance measuring device for a vehicle, which can control a scanning range based on vehicle information such as a vehicle speed in a distance measuring device mounted on the vehicle.

Disclosure of Invention

However, patent document 1 describes a distance measuring device capable of enlarging a scanning range by changing the maximum scanning angle γ, but when the scanning range is enlarged, there is a problem that the spatial resolution is lowered.

Accordingly, an object of the present invention is to provide an optical scanning device capable of performing optical scanning without lowering spatial resolution even when a scanning range is expanded.

An aspect of the present invention provides an optical scanning device including: a light source emitting light; a scanning mirror that reflects light incident from the light source by a reflection surface, and that can independently oscillate around a 1 st axis passing through the reflection surface and a 2 nd axis orthogonal to the 1 st axis and passing through the reflection surface; and a control unit that controls a 1 st frequency and a 1 st amplitude of the scanning mirror oscillating about the 1 st axis and a 2 nd frequency and a 2 nd amplitude of the scanning mirror oscillating about the 2 nd axis to scan the light reflected by the reflection surface of the scanning mirror, wherein the optical scanning device scans a scanning range defined by a maximum scanning angle in a main scanning direction and a maximum scanning angle in a sub-scanning direction by the light emitted from the light source, the maximum scanning angle in the main scanning direction changing in accordance with the 1 st amplitude, the sub-scanning direction being orthogonal to the main scanning direction, and the maximum scanning angle in the sub-scanning direction changing in accordance with the 2 nd amplitude. The control unit controls the 2 nd frequency according to the maximum scanning angle in the sub-scanning direction.

According to the present invention, an optical scanning device can be obtained which can prevent a decrease in spatial resolution by controlling the frame rate based on information such as acceleration and angular velocity.

Drawings

Fig. 1 is a schematic view showing an optical scanning device and a vehicle mounted with the optical scanning device according to embodiment 1 of the present invention.

Fig. 2 is a schematic plan view of a substrate of an optical scanning device according to embodiment 1 of the present invention.

Fig. 3 is a schematic cross-sectional view of the 2-dimensional scanning mirror of the substrate of fig. 2 viewed in the III-III direction.

Fig. 4 is a schematic cross-sectional view of the acceleration sensor of the substrate of fig. 2 viewed in the direction IV-IV.

Fig. 5 is a schematic cross-sectional view of the acceleration sensor of the substrate of fig. 2 viewed in the V-V direction.

Fig. 6 is a schematic cross-sectional view of the SOI substrate before processing.

Fig. 7 is a schematic diagram showing a relationship between the inclination angle of the mirror portion of the 2-dimensional scanning mirror and the traveling direction of the light beam reflected by the mirror portion.

Fig. 8 is a schematic view showing a scanning range by a light beam emitted from the optical scanning device according to embodiment 1 of the present invention.

Fig. 9 is a schematic diagram showing an example of a scanning path and a scanning point by a light beam emitted from the optical scanning device according to embodiment 1 of the present invention.

Fig. 10 is a graph showing an example of the relationship between the acceleration and the maximum scanning angle of the optical scanning device according to embodiment 1 of the present invention.

Fig. 11 is a schematic diagram showing a scanning path and a scanning point of a ranging apparatus based on the related art at the time of acceleration.

Fig. 12 is a schematic diagram showing a scanning path and a scanning point of a ranging apparatus based on the related art at the time of deceleration.

Fig. 13 is a flowchart showing a method of changing the driving frequency (frame rate) in accordance with the acceleration without deteriorating the spatial resolution.

Fig. 14 is a schematic diagram showing a scanning path and a scanning point of the optical scanning device according to embodiment 1 of the present invention.

Fig. 15 is a flowchart showing a method of changing the maximum scan angle in accordance with the acceleration without deteriorating the spatial resolution.

Fig. 16 is a graph showing an example of the relationship between the acceleration and the driving frequency (frame rate) of the optical scanning device according to embodiment 1 of the present invention.

Fig. 17 is a schematic diagram showing a configuration of an optical scanning device according to embodiment 1 of the present invention.

Fig. 18 is a schematic diagram showing a configuration of an optical scanning device according to a 2 nd modification of embodiment 1 of the present invention.

Fig. 19 is a schematic diagram showing a configuration of an optical scanning device according to embodiment 2 of the present invention.

Fig. 20 is a graph showing an example of the relationship between the angular velocity and the maximum scanning angle of the optical scanning device according to embodiment 2 of the present invention.

Fig. 21 is a schematic diagram showing a scanning path and a scanning point of a ranging apparatus based on the related art when proceeding straight.

Fig. 22 is a schematic diagram showing a scanning path and a scanning point of a ranging apparatus according to the related art when turning.

Fig. 23 is a flowchart showing a method of changing the drive frequency (frame rate) in accordance with the angular velocity without deteriorating the spatial resolution.

Fig. 24 is a schematic diagram showing a scanning path and a scanning point of the optical scanning device according to embodiment 2 of the present invention.

Fig. 25 is a schematic diagram showing a configuration of an optical scanning device according to embodiment 3 of the present invention.

Fig. 26 is a schematic plan view of a substrate of an optical scanning device according to embodiment 3 of the present invention.

Fig. 27 is a schematic cross-sectional view of the 2-dimensional scanning mirror of the substrate of fig. 26 viewed in the XXV-XXV direction.

Fig. 28 is a schematic view showing the optical axis of a light beam emitted from the optical scanning device according to embodiment 3 of the present invention.

Fig. 29 is a schematic view showing a vehicle mounted with an optical scanning device according to embodiment 3 of the present invention.

Fig. 30 is a schematic diagram showing a scanning path and a scanning point of the optical scanning device according to embodiment 3 of the present invention.

Fig. 31 is a schematic diagram showing scanning paths and scanning points of the optical scanning device according to embodiment 3 of the present invention in a case where the maximum scanning angle is increased from fig. 30 without changing the frequency (frame rate) of amplitude change.

Fig. 32 is a flowchart showing a method of changing the frequency (frame rate) of amplitude change in accordance with acceleration without deteriorating the spatial resolution.

Fig. 33 is a schematic diagram showing a scanning path and a scanning point of the optical scanning device according to embodiment 3 of the present invention.

Fig. 34 is a schematic diagram showing a configuration of an optical scanning device according to embodiment 4 of the present invention.

Fig. 35 is a graph showing an example of the relationship between the speed and the maximum scanning angle of the optical scanning device according to embodiment 4 of the present invention.

Fig. 36 is a flowchart showing a method of changing the drive frequency in accordance with the speed without deteriorating the spatial resolution.

(symbol description)

100. 200, 300, 400: an optical scanning device; 101: a light source; 102: a substrate; 103: a control unit; 104: a beam splitter; 105: an acceleration sensor; 106: a 2-dimensional scanning mirror; 109: fixing the mirror; 111: a mirror section; 113: a frame; 115: a reflective film; 120: a beam; 121: an insulating film; 122: a 1 st electrode; 123: a piezoelectric film; 124: a 2 nd electrode; 125: a beam base; 131: an inertial mass body; 132: a beam; 133: comb electrodes; 134: fixing comb electrodes; 135: a movable comb-tooth electrode; 140: an SOI substrate; 141: a support layer; 142: an insulating layer; 143: an active layer; 150: a vehicle; 202: a substrate; 207: an angular velocity sensor; 302: a substrate; 306: a 2-dimensional scanning mirror; 308: a scan angle conversion unit; 321-324: a beam; 350: a vehicle.

Detailed Description

An optical scanning device according to an embodiment of the present invention will be described below with reference to the drawings. In each embodiment, the same components are denoted by the same reference numerals, and description thereof is omitted.