Search

EP-4325269-B1 - OPTICAL SCANNING DEVICE

EP4325269B1EP 4325269 B1EP4325269 B1EP 4325269B1EP-4325269-B1

Inventors

  • TAKAO, YOSHIFUMI
  • SAKURAI, MAKOTO
  • Nakazawa, Katsunori
  • MATSUMARU, NAOYA
  • YAMAMOTO, ATSUSHI
  • IDRIS, Nazirul Afham

Dates

Publication Date
20260506
Application Date
20220418

Claims (7)

  1. An optical scanning device (10), comprising: a substrate (15), a light source (17) which is mounted on the substrate (15) and emits a light beam (Lp), a MEMS optical deflector (20) which has a mirror portion (21) whose upper surface side is a mirror surface, and an actuator which reciprocally rotates the mirror portion around an axis, and is mounted on the substrate; at least one optical path generation mirror (23, 25) configured to generate an optical path which causes the light beam (Lp) emitted from the light source (17) to enter the mirror portion (21) of the MEMS optical deflector (20), and fixed so that the at least one optical path generation mirror (23, 25) is not capable of being displaced, a lens (19) arranged between the light source (17) and the optical path generation mirror (23) on which light emitted from the light source (17) first enters in the optical path, and a first shielding plate (41, 45), with any of the optical path generation mirrors (23, 25) as a corresponding optical path generation mirror in the optical path, including a first elliptical aperture (42, 46) arranged in the same inclining direction as the inclining direction of the corresponding optical path generation mirror (23, 25) upstream of the corresponding optical path generation mirror (23, 25) and with respect to an optical axis (Cl) of the optical path.
  2. The optical scanning device according to claim 1, wherein the first shielding plate (41, 45) is attached to the corresponding optical path generation mirror (23, 25), and wherein when the direction of the optical axis (C1) is viewed from the downstream side with respect to the corresponding optical path generation mirror (23, 25) in the optical path, the first elliptical aperture (42, 46) of the first shielding plate (41, 45) becomes a circular shape in which a ratio of a major axis of the first elliptical aperture (42, 46) to a minor axis of the first elliptical aperture (42, 46) is closer to 1 than when the first shielding plate (41, 45) is viewed from the vertical direction.
  3. The optical scanning device according to claim 1 or 2, further including a second shielding plate (45) having a second elliptical aperture (46), which is provided downstream of the first shielding plate (41) on the optical path, wherein ratios of the major axes of the elliptical apertures (42, 46) of the respective shielding plates (41, 45) to the minor axes of the elliptical apertures (42, 46) are different from each other.
  4. The optical scanning device according to claim 3, wherein an aperture area of the elliptical aperture (46) of the second shielding plate (45) is smaller than an aperture area of the elliptical aperture (42) of the first shielding plate (41).
  5. The optical scanning device according to any one of claims 1 to 4, wherein at least one of the optical path generation mirrors (53) is a concave mirror.
  6. The optical scanning device according to claim 1 or 2, wherein further, a second shielding plate (45) having a second aperture (46) is arranged downstream of the first shielding plate (41) on the optical path, wherein the light beam (Lp) forms an irradiation region larger than the first elliptical aperture (42) with respect to the first shielding plate (41), and wherein the second shielding plate (45) is arranged at a position where the light beam passes through an inside of the second aperture (46).
  7. The optical scanning device according to claim1, wherein the MEMS optical deflector (20) is configured to perform two-dimensional scanning.

Description

Technical Field The present invention relates to an optical scanning device having a MEMS optical deflector. Background Art JP 6734532 B discloses an optical scanning device having a MEMS optical deflector. The optical scanning device is attached to a temple (side support) on one side of a spectacles-type head mount, emits scanning light from the MEMS optical deflector toward lenses and half mirrors arranged toward the front (front frame) of the spectacles, and projects an image on the user's retina by the scanning light reflected by the half mirror. According to the schematic diagram of JP 6734532 B, the lens and the half mirror are mounted on the temple in addition to the optical scanning device, and the optical scanning device faces the half mirror with the lens interposed therebetween. Laser light emitted from the optical scanning device scans on the half mirror along the mirror surface thereof, is reflected by the mirror surface, and projects an image onto the retina of a user's eye. US 2008/049289 A1 discloses an optical deflector which includes a substrate portion, a reflecting portion which can swing about a swinging motion axis with respect to the substrate portion, and an aperture stop portion which includes an aperture and blocks at least part of a light beam other than a light beam entering the aperture among an incident luminous flux to the optical deflector. The aperture allows passage of the incident luminous flux toward the reflecting portion and that of an emergent luminous flux reflected by the reflecting portion. At least part of an aperture rim of the aperture stop portion has a shape that makes the width of the aperture narrower from a light-beam-incoming side toward a reflecting portion side. JP 2015 022158 A discloses an optical scanner and image display device. Therein, a light beam from a light source is converted to a parallel light beam by a coupling lens and is shaped by a first aperture to impinge on a light deflector. A second aperture is arranged between the first aperture and the light deflector. The second aperture blocks diffracted light from the first aperture. Light reaching the light deflector is light obtained by diffracting the diffracted light from the first aperture further by the second aperture. Thus, the diffracted light reaching the light deflector remains, but has the intensity very reduced. Summary of Invention Technical Problem JP 6734532 B does not disclose in what positional relationship, the light source, the MEMS optical deflector, and the substrate are mounted in the optical scanning device specifically. An object of the present invention is to provide an optical scanning device which has improved the quality of a light beam emitted as scanning light. Solution to Problem An optical scanning device of the present invention is provided as set forth in claim 1. Preferred embodiments of the present invention may be gathered from the dependent claims. Advantageous Effects of Invention According to the present invention, a shielding plate arranged for a corresponding optical path generation mirror has an aperture. Thus, a light beam can be improved into a light beam with high contrast as a result of cutting a peripheral low brightness area by the aperture. Brief Description of Drawings FIG. 1A is a plan view of an optical scanning device;FIG. 1B is a view taken along arrow 1B in FIG. 1A;FIG. 1C is a view taken along arrow 1C in FIG. 1A;FIG. 1D is a view taken along arrow 1D in FIG. 1A;FIG. 2 is a side view of a support frame body;FIG. 3 is a view showing a spectacles-type video display device 155 as an application example of the optical scanning device;FIG. 4A is a detailed diagram of a positional relationship of optical elements of an optical scanning device in which an optical path of a light beam is arranged;FIG. 4B is a view taken along arrow 4B in FIG. 4A;FIG. 4C is a view taken along arrow 4C in FIG. 4A;FIG. 4D is a view taken along arrow 4D in FIG. 4A;FIG. 4E is a view taken along arrow 4E in FIG. 4A;FIG. 5 is a configuration view of a main part of an optical scanning device having a concave mirror instead of a plate-like mirror;FIG. 6 is a view showing the shape of a light spot when a projection screen is inclined with respect to an optical axis; andFIG. 7 is a schematic view of a main part of an optical scanning device equipped with VCSELs of RGB. Description of Embodiments A plurality of preferred embodiments of the present invention will be described in detail with reference to the drawings. It goes without saying that the present invention is not limited to the following embodiments. In addition to the following embodiments, the present invention includes various configuration modes within the scope of the appended claims. The same elements are given the same reference numerals through all the drawings. (Overall Configuration) FIG. 1A is a plan view of an optical scanning device 10, FIG. 1B is a view taken along arrow 1B in FIG. 1A, FIG. 1C is a vie