JP7247618B2 - Optical scanning device and optical scanning method - Google Patents

Description

The present invention relates to an optical scanning device and an optical scanning method, and more particularly to enlargement of a scanning angle in optical scanning.

Optical scanning devices are used in various optical systems such as copiers, laser printers, laser plotters, facsimiles, laser displays or laser microscopes. The optical scanning device has a movable reflector. The movable reflector is rotatable. By adjusting the angle of the movable reflector, the scanning angle of the light reflected by the movable reflector can be adjusted.

Patent Document 1 describes an example of an optical scanning device. The optical scanning device has a movable reflector and a fixed reflector. The fixed reflector faces the movable reflector. The light incident on the movable reflecting section is repeatedly reflected between the movable reflecting section and the fixed reflecting section along the direction parallel to the rotation axis of the movable reflecting section. The scanning angle of the light reflected N times by the movable reflecting portion having the angle α is 2Nα. Therefore, the scanning angle in optical scanning can be increased by multiple reflections between the movable reflecting portion and the fixed reflecting portion.

Patent Documents 2 and 3 describe an example of an optical scanning device. The optical scanning device has a movable reflector and two fixed reflectors. The two fixed reflectors are arranged above the movable reflector along a direction parallel to the rotation axis of the movable reflector. The light that has passed between the two fixed reflectors and entered the movable reflector is repeatedly reflected between the movable reflector and the two movable reflectors, and is emitted after passing between the two fixed reflectors. be. Multiple reflections between the movable reflector and the two fixed reflectors can increase the scanning angle in optical scanning.

JP-A-4-80709 JP-A-2003-172897 JP 2004-177487 A

The present inventors studied the expansion of the scanning angle in optical scanning, and further studied the expansion of the scanning angle by optical scanning different from the methods described in Patent Documents 1-3. For example, in the optical scanning described in Patent Documents 1 to 3, since multiple reflection occurs between the movable reflecting portion and the fixed reflecting portion along the direction parallel to the rotation axis of the movable reflecting portion, the rotation of the movable reflecting portion The area of the movable reflector can increase along the direction parallel to the axis.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to enlarge the scanning angle in optical scanning by means of a small movable reflecting portion.

An optical scanning device according to the present invention includes a movable reflector and a plurality of fixed reflectors. The plurality of fixed reflectors includes a first fixed reflector and a second fixed reflector. The light reflected by the movable reflector for the first time is reflected by the movable reflector for the second time after being reflected by the first fixed reflector and the second fixed reflector.

An optical scanning method according to the present invention comprises causing light to be reflected for the first time by a movable reflecting section, and reflecting this light by a first fixed reflecting section and a second fixed reflecting section among a plurality of fixed reflecting sections. and subjecting this light to a second reflection by the movable reflector.

According to the present invention, the scanning angle in optical scanning can be enlarged by a small movable reflecting portion.

1 is a perspective view of an optical scanning device according to an embodiment; FIG. FIG. 2 is a plan view of an example of details of an optical scanning main body used in the movable reflector shown in FIG. 1; 2 is a cross-sectional view of an example of details of the optical member shown in FIG. 1; FIG. FIG. 11 is a side view of an optical scanning device according to Modification 1; FIG. 11 is a side view of an optical scanning device according to Modification 2; 4 shows simulation results of an optical scanning device. 4 shows simulation results of an optical scanning device.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in all the drawings, the same constituent elements are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

FIG. 1 is a perspective view of an optical scanning device 20 according to an embodiment.

The optical scanning device 20 includes a movable reflector 100 and a plurality of fixed reflectors 212 (two fixed reflectors 212 in the example shown in FIG. 1). The plurality of fixed reflectors 212 includes first fixed reflectors 212a and second fixed reflectors 212b. The light L that has been reflected for the first time by the movable reflecting section 100 is reflected by the movable reflecting section 100 for the second time after being reflected by the first fixed reflecting section 212 a and the second fixed reflecting section 212 b. In other words, the light L does not enter the movable reflector 100 during reflection by the first fixed reflector 212a and the second fixed reflector 212b.

According to this embodiment, the scanning angle in optical scanning can be enlarged by the small movable reflecting section 100 . Specifically, in this embodiment, the light L can be reflected by the movable reflector 100 at least twice. Therefore, as will be described later in detail, the scanning angle in optical scanning can be expanded. Furthermore, in the present embodiment, the positions at which the light L is incident on the movable reflector 100 for the second time can be adjusted by the plurality of fixed reflectors 212 . That is, the position where the light L is incident on the movable reflecting section 100 for the second time can be brought closer to the position where the light L is incident on the movable reflecting section 100 for the first time. Therefore, the size of the movable reflector 100 can be reduced.

In the example shown in FIG. 1, the light L enters the movable reflector 100 from one side (side S1) of the movable reflector 100 before being reflected by the first fixed reflector 212a and the second fixed reflector 212b. , and reflected by the first fixed reflector 212a and the second fixed reflector 212b, the light is reflected by the movable reflector 100 toward the side (side S2) opposite to the side S1 of the movable reflector 100. FIG. The light L travels along the optical path from the side S2 to the side S1 (in the example shown in FIG. 1, the optical path of the light L is The portion between the first fixed reflector 212a and the second fixed reflector 212b) is traced.

According to this embodiment, the size of the movable reflecting section 100 can be reduced in the direction from the side S1 to the side S2. Specifically, in this embodiment, the light L follows an optical path from the side S2 to the side S1 during at least part of the reflections by the first fixed reflector 212a and the second fixed reflector 212b. Therefore, in the direction from the side S1 to the side S2, the position where the light L is incident on the movable reflecting section 100 for the second time can be brought closer to the position where the light L is incident on the movable reflecting section 100 for the first time. Therefore, the size of the movable reflector 100 can be reduced in the direction from the side S1 to the side S2.

Details of the optical scanning device 20 will be described with reference to FIG.

The optical scanning device 20 includes a movable reflector 100 and an optical member 200 .

The movable reflector 100 is rotatable about the rotation axis R. As shown in FIG. The movable reflector 100 is driven by resonance driving, for example electrostatic force driving, electromagnetic driving or piezoelectric element driving. The movable reflector 100 is along the direction H (for example, the horizontal direction) in the stationary state. In the example shown in FIG. 1, the movable reflector 100 is tilted from the direction H by an angle α.

The optical member 200 has two fixed reflectors 212 (a first fixed reflector 212 a and a second fixed reflector 212 b ) and a transmission surface 220 . In the optical scanning method according to this embodiment, the light L is reflected by the movable reflector 100 and enters the optical member 200 via the transmission surface 220 . The light L is then transmitted through the optical member 200 and reflected by the first fixed reflecting portion 212a. The light L is then transmitted through the optical member 200 and reflected by the second fixed reflecting portion 212b. The light L is then transmitted through the optical member 200 and emitted from the optical member 200 via the transmission surface 220 . The light L is then reflected again by the movable reflector 100 .

The light L can be incident on the movable reflector 100 along a direction parallel to the rotation axis R of the movable reflector 100 when viewed from a direction V (for example, vertical direction) perpendicular to the direction H. In this case, the light L is incident on the movable reflector 100 inclined at an angle α from the direction H when viewed in a direction parallel to the rotation axis R at an incident angle α. The light L is reflected again by the movable reflector 100 after being reflected by the first fixed reflector 212a and the second fixed reflector 212b. The light L is emitted in a direction tilted from the direction V by the scanning angle θ. The scanning angle θ is 2Nα when the light L is reflected N times by the movable reflector 100 .

The light L may be incident on the movable reflector 100 along a direction perpendicular to the rotation axis R of the movable reflector 100 when viewed from a direction V perpendicular to the direction H. In this case, when viewed from the direction V, the fixed reflectors 212 are arranged along the direction perpendicular to the rotation axis R of the movable reflector 100 .

In the example shown in FIG. 1, the light L is reflected twice by the movable reflecting section 100, but the light L may be reflected by the movable reflecting section 100 three times or more. For example, the light L may be reflected by the movable reflector 100 for the second time, then be reflected by the fixed reflector 212 of the optical member 200 again, and be reflected by the movable reflector 100 again.

FIG. 2 is a plan view of an example of details of the optical scanning main body 10 used in the movable reflector 100 shown in FIG.

The optical scanning main body 10 includes a frame 110 , movable electrodes 120 , shaft members 130 and fixed electrodes 140 . The movable electrode 120 functions as the movable reflector 100 shown in FIG. 1, and the shaft member 130 functions as the rotation axis R shown in FIG.

The movable electrode 120 has a reflective surface on which a reflective layer (eg, a metal layer, specifically, an aluminum layer, for example) is formed. Light irradiated from the outside of the optical scanning main body 10 is reflected by the reflecting surface of the movable electrode 120 . Light can be reflected in a desired direction by adjusting the angle of the movable electrode 120 .

The movable electrode 120 is attached to the frame 110 by two shaft members 130 . One of the two shaft members 130 is connected to one of two opposing sides of the movable electrode 120, and the other of the two shaft members 130 is connected to the opposing side of the movable electrode 120. connected to the other of the two sides that The shaft member 130 functions as a rotating shaft for the movable electrode 120 .

The movable electrode 120 has one side between the two sides to which the shaft member 130 is connected and on which a comb-tooth electrode is formed, and another side between the two sides to which the shaft member 130 is connected and on which the comb-tooth electrode is formed. are doing.

The fixed electrode 140 has a comb-teeth electrode. The fixed electrode 140 faces the movable electrode 120 such that a gap is formed between the comb-teeth electrode of the fixed electrode 140 and the comb-teeth electrode of the movable electrode 120 . In the example shown in FIG. 2, one fixed electrode 140 faces one comb tooth electrode of the movable electrode 120, and another fixed electrode 140 faces another comb tooth electrode of the movable electrode 120. In the example shown in FIG. ing. The movable electrode 120 vibrates due to the electrostatic force generated by the voltage between the movable electrode 120 and the fixed electrode 140 .

In the example shown in FIG. 2, the optical scanning body 10 can be formed by selectively etching a conductive material, eg a silicon substrate.

FIG. 3 is a cross-sectional view of an example of details of the optical member 200 shown in FIG.

The optical member 200 includes a translucent member 200a. The translucent member 200a is made of a translucent material such as glass or resin.

The translucent member 200a has a surface 202a, a surface 202b and a surface 202c. In the example shown in FIG. 3, the translucent member 200a has a substantially triangular shape. The triangle may not be strictly triangular, eg it may have rounded corners. The translucent member 200a may have a shape other than a triangular shape (for example, a polygonal shape other than a triangular shape).

Surface 202a and surface 202b are covered by reflective layer 210 . The reflective layer 210 is for example a metal layer, more specifically for example an aluminum layer. The reflective layer 210 can be formed by vapor deposition, for example. The reflective layer 210 functions as a fixed reflector 212 . Thus, the optical member 200 has a plurality of surfaces (surfaces 202a and 202b) on which a plurality of fixed reflection portions 212 (first fixed reflection portion 212a and second fixed reflection portion 212b) are formed. there is

Face 202c is not covered by reflective layer 210 . Surface 202 c can function as transmissive surface 220 . An antireflection coating may be formed on the surface 202c.

The light L shown in FIG. 1 enters the optical member 200 via the transmission surface 220 before being reflected by the first fixed reflector 212a and the second fixed reflector 212b, and is reflected by the first fixed reflector 212a. and second fixed reflecting portion 212b, the light is transmitted through the optical member 200, reflected by the first fixed reflecting portion 212a and the second fixed reflecting portion 212b, and then passes through the transmitting surface 220. Then, the light is emitted from the optical member 200 .

According to this embodiment, the arrangement of the plurality of fixed reflecting portions 212 can be easily adjusted. Specifically, in the present embodiment, the arrangement of each of the plurality of fixed reflectors 212 can be determined by the shape of the translucent member 200a. The shape of the translucent member 200a can be easily adjusted. Therefore, it is possible to easily adjust the arrangement of the plurality of fixed reflectors 212 .

The optical scanning device 20 can be used in various optical systems such as copiers, laser printers, laser plotters, facsimiles, laser displays or laser microscopes.

(Modification 1)
FIG. 4 is a side view of the optical scanning device 20 according to Modification 1. As shown in FIG. The optical scanning device 20 according to Modification 1 is the same as the optical scanning device 20 according to the embodiment except for the following points.

The optical member 200 further includes a third fixed reflector 212c. The light L is reflected by the third fixed reflector 212c between the reflection of the first fixed reflector 212a and the reflection of the second fixed reflector 212b. In the example shown in FIG. 4 as well, similarly to the embodiment, the scanning angle in optical scanning can be enlarged by the small movable reflecting section 100 .

In the example shown in FIG. 4, the cross-sectional shape of the optical member 200 has a substantially rectangular shape. The quadrilateral need not be an exact quadrilateral, for example it may have rounded corners. The light L is sequentially reflected by the first fixed reflector 212a, reflected by the third fixed reflector 212c, and reflected by the second fixed reflector 212b.

(Modification 2)
FIG. 5 is a side view of an optical scanning device 20 according to Modification 2. As shown in FIG. The optical scanning device 20 according to Modification 2 is the same as the optical scanning device 20 according to the embodiment except for the following points.

The plurality of fixed reflectors 212 may be arranged independently of each other. In the example shown in FIG. 5, the first fixed reflector 212a and the second fixed reflector 212b are mirrors arranged independently of each other. In the example shown in FIG. 5, similarly to the embodiment, the scanning angle in optical scanning can be enlarged by the small movable reflecting section 100. In the example shown in FIG.

The optical scanning device 20 according to the example was manufactured as follows.

The movable reflector 100 was formed by micromachining a silicon substrate. Aluminum was vapor-deposited on the surface of the movable reflector 100 .

The optical member 200 was an equilateral triangular prism with a side of 2 mm and a height of 5 mm. The first fixed reflector 212a and the second fixed reflector 212b were formed by aluminum vapor deposition. An antireflection coating was formed on the transmissive surface 220 .

The distance between the surface of the movable reflector 100 and the transmission surface 220 of the optical member 200 was set to 1.5 mm when the movable reflector 100 was stationary.

The light L was red laser beam collimator light with a diameter of 1.0 mm.

The tilt angle α of the movable reflecting portion 100 was set to 10°, and the light L was scanned by the optical scanning main body 10 . The scanning angle θ was 36°. The scanning angle θ almost coincided with the ideal value (40°).

6 and 7 show simulation results of the optical scanning device 20. FIG. The scanning angle θ of the optical scanning main body 10 according to the example also agreed with the simulation results shown in FIGS. 6 and 7 .

Although the embodiments of the present invention have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than those described above can also be adopted.

10 Optical scanning main body 20 Optical scanning device 100 Movable reflector 110 Frame body 120 Movable electrode 130 Shaft member 140 Fixed electrode 200 Optical member 200a Translucent member 202a Surface 202b Surface 202c Surface 210 Reflective layer 212 Fixed reflector 212a First fixed reflector Part 212b Second fixed reflector 212c Third fixed reflector 220 Transmission surface

Claims (4)

a movable reflector rotatable about a rotation axis extending from a predetermined side toward a side opposite to the one side;
A first fixed reflection that reflects, toward the one side, light incident on the movable reflecting section from the one side, receiving a first reflection by the movable reflecting section, and reflected toward the opposite side. Department and
a second fixed reflector that reflects the light reflected by the first fixed reflector toward the movable reflector ;
including
the light reflected by the second fixed reflecting portion is reflected for the second time by the movable reflecting portion ;
An optical scanning device, wherein a position where the light is reflected for the first time on the movable reflecting section and a position where the light is reflected for the second time on the movable reflecting section are different from each other. The optical scanning device according to claim 1 , wherein
further comprising an optical member provided with the first fixed reflector and the second fixed reflector and having a translucent surface;
Before the light is reflected by the first fixed reflector and the second fixed reflector, the light enters the optical member via the translucent surface, is reflected by the first fixed reflector and is reflected by the second fixed reflector. During at least part of the reflection by the fixed reflecting section, the light passes through the optical member, is reflected by the first fixed reflecting section and the second fixed reflecting section, and then passes through the translucent surface. An optical scanning device emitted from an optical member. 3. The optical scanning device according to claim 1 , wherein
The optical scanning device further includes a third fixed reflector that reflects the light reflected by the first fixed reflector toward the second fixed reflector . Light is incident from one side on a movable reflecting portion rotatable about a rotation axis extending from a predetermined side toward the side opposite to the one side, and is reflected for the first time by the movable reflecting portion. subjecting the light to reflecting the light toward the opposite side ;
Reflecting the light toward the one side by a first fixed reflecting section after the light is reflected for the first time by the movable reflecting section ;
After the light is reflected by the first fixed reflector, the second fixed reflector reflects the light toward the movable reflector;
causing the light to undergo a second reflection by the movable reflector after the light has been reflected by the second fixed reflector;
including
The optical scanning method, wherein a position where the light is reflected for the first time on the movable reflecting part and a position where the light is reflected for the second time on the movable reflecting part are different from each other.

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