JP2010156721A - Optical scanning module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein the freedom of an optical layout is increased by tilting a scanning mirror, but the corner part projected by the tilt of the scanning mirror needs a large space when the mirror rotates, the main axis of inertia of the moving part is tilted with respect to the central axis of rotation, and thus the rotary motion becomes instable. <P>SOLUTION: Both lower end corners remotest from the central axis of rotation of the scanning mirror 21 of the optical scanning module are diagonally cut off, and the optical scanning module has a squeezed form in which the external dimension reduces as the location is remoter from the focal point of a concave face in the height direction, thus the difference between the circular trajectory of the lower end corners and the circular trajectory of the lower central part is smaller than that of a conventional rectangular scanning mirror. With this form, the tilt of the whole main inertial axis of a movable component is improved, the rocking scanning mirror 21 has a substantially the same moment of inertia for the upper and the lower ends, thus the operation is stabilized. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical scanning module equipped with a scanning mirror that irradiates laser light that is scanned to read information.

  In general, there is known an information reading device that irradiates a character symbol such as a bar code printed on an article or tag so as to scan a laser beam and reads information described from reflected light (returned light). The information reading apparatus includes a light source unit that generates laser light, a mirror driving device that scans the laser light on a barcode by repetitively operating (shaking operation) within a predetermined range while reflecting the laser light, and a photodiode. An information reading unit made of (PD) or the like that reads information from the return light from the barcode is mounted on the base member.

  The light source unit is disposed obliquely in front of the mirror driving device outside the width region of the return light, and the information reading unit is configured to collect the return light below the optical axis of the laser light emitted in front of the mirror driving device 3. Arranged in the illuminated position.

  With such an arrangement, the laser beam emitted from the light source unit is reflected by the plane mirror unit (emission unit) of the scanning mirror that is oscillated by the mirror driving device, scanned at a predetermined angular width, and read. The cord is irradiated. The return light (reflected light) reflected on the barcode is condensed by the spherical mirror part (condensing part) of the scanning mirror and is incident on the information reading part.

This scanning mirror has an integral configuration in which a plane mirror portion is arranged at the center of a concave mirror portion for condensing incident return light at one focal point. In the height direction of the scanning mirror, the focal position of the concave mirror is offset from the center of the outer shape of the mirror, and the outer shape of the scanning mirror forms a rectangle.
JP-A-8-16705

  In the above-described condensing mirror portion, tilting the scanning mirror and offsetting the focal position is effective in increasing the degree of freedom in optical layout.

  On the other hand, the following problems also occur. First, when the rectangular scanning mirror is tilted so that the focal position is upward, the two mirror outer corner angles farther from the concave focus in the height direction of the scanning mirror protrude as the farthest end with respect to the rotation axis. More space is required during rotation. This is a big problem when the reading apparatus is modularized when it is intended to improve both reading performance and size of the apparatus by increasing the size of the condenser mirror. Second, since the scanning mirror has an asymmetric shape with respect to the rotation axis direction, the inertial main axis of the movable part is inclined with respect to the rotation center axis, and the rotation operation is unstable.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical scanning module that solves the above-described problems, improves the reading performance, and improves the rotational operation stability while reducing the size.

  In order to achieve the above object, an embodiment according to the present invention includes a laser light source unit that emits laser light, a scanning mirror that reflects the laser light and irradiates a reading object, and the scanning mirror. An optical scanning module comprising: a mirror driving unit that swings in a direction; and a light receiving unit that photoelectrically converts return light reflected by the reading object, wherein the scanning mirror includes a plane mirror unit for emission; And a condensing mirror for reading having a concave shape with a focal point at the position of the light receiving unit, and further formed far from the focal point of the scanning mirror when viewed from the rotation axis direction of the scanning mirror. Provided is an optical scanning module in which the outer shape of a scanning mirror is adjusted so as to be narrowed so that the trajectories at the time of a rotation operation of each side forming the side end portion substantially coincide with each other.

  According to the present invention, it is possible to provide an optical scanning module that is downsized and has improved reading performance and rotational operation stability.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
An optical scanning module according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing an external configuration of the optical scanning module according to the first embodiment. FIG. 2 is a diagram illustrating the configuration of the optical scanning module with the upper lid removed.

First, the outline and appearance of the optical scanning module will be described.
The external dimensions realized in the optical scanning module 1 are, for example, a rectangular parallelepiped shape having a width of about 21 mm, a depth of 14 mm, and a height of about 11 mm. Of course, the numerical values of these external dimensions are only examples, and can be realized with numerical values below these. Moreover, if it is a certain range, an external dimension can also be changed according to the mounting space of an electronic device. In the following description of the embodiment, the surface of the optical scanning module that is orthogonal to the central axis of the scanning light (laser light) irradiation direction (scanning angle) is defined as the scanning aperture surface (front surface), and the reflected light (returned light) is used. The direction in which the surface of the scanning mirror that receives light (the exit surface / reflection surface) faces will be described as the irradiation / light reception direction. That is, in FIG. 1, when the surface of the scanning mirror is viewed from the scanning aperture surface, it is directed obliquely.

  The optical scanning module 1 includes a housing 2 serving as an exterior having a strength capable of withstanding an impact such as dropping. The housing 2 includes a base member 2a for mounting each component and a substrate unit 2b serving as an upper lid. The substrate unit 2b is fixed to a plurality of support members 2c planted on the base member 2a by screws 2d. In addition, as a fixing method, a hook and a stopper may be respectively formed and fixed by fitting or fixing with an adhesive may be used.

The optical scanning module 1 has, for example, a fixing screw hole formed on the lower surface of the base member 2a so that it can be mounted on various electronic devices as one unit of an optical reading function.
A connector 11 and a control unit 12 are provided on the board unit 2b. The control unit 12 includes a circuit board on which a control circuit, a signal processing circuit, and the like for driving and signal processing of each unit and component to be described later are formed. The connector 11 is connected to an external device such as a computer (not shown) through a cable or the like. For example, the computer supplies a power supply voltage to the optical scanning module to drive and control the optical scanning module 1. For example, in accordance with an instruction (command) of a computer of the mounted electronic device, barcode reading is started, the scanning mirror is swung, and the scanned laser light (scanning light) is irradiated. When a barcode is placed on the scanning light, the barcode is read.

The configuration of the optical scanning module 1 will be described with reference to FIG.
On the base member 2a, a light source unit 3, a folding mirror 5, an optical scanning device 4, and a light detection unit 6 are mounted as main components.

Although not shown, the light source unit 3 includes a laser diode (LD) that emits laser light, a collimator lens, and an emission aperture. In this configuration, the collimator lens collimates the laser light emitted from the laser diode. The exit aperture generates a desired shape and spot size by narrowing the cross section of the collimated laser beam. These LD, collimator lens, and emission aperture are appropriately arranged and distanced according to the reading specification (design), and are accommodated as a unit in an accommodating portion (not shown).
The laser light emitted from the light source unit 3 is deflected by reflection by the folding mirror 5 and travels toward the optical scanning device 4.

  In the optical scanning device 4, the scanning mirror 21, the bearing portion 23, and the driving portion 22 are integrally joined by resin molding. The bearing portion 23 is rotatably fitted on a rotary shaft 24 planted on the base member 2a so as to be rotatable. The drive part 22 is comprised by the drive coil 25, the leaf | plate spring 28, the support spring holding member 27, and the magnet 29 arrange | positioned on the base member 2a.

  As will be described later, a condensing mirror 21a having an aspherical surface and curved in a concave shape is formed on the front surface of the scanning mirror 21, and a flat and rectangular output mirror 21b is provided at the approximate center thereof. The exit mirror 21b and the condensing mirror 21a are integrally formed by resin molding, and the shape and orientation are preliminarily set so that the captured light is directed to the photodetector even when the scanning angle (scanning angle) varies. Is properly designed. The exit mirror 21b and the condensing mirror 21a of the resin-molded scanning mirror 21 are formed on a mirror surface on which a gold thin film is deposited by vacuum deposition. This mirror surface is manufactured so that the vertical reflectance with respect to the wavelength of the laser beam is about 90%.

  The scanning mirror 21 is swung in the scanning direction described later by the rotation of the bearing portion 23. The drive unit 22 includes a drive coil 25, a leaf spring 26, a support spring holding member 27, and a magnet 29 disposed on the yoke.

  In this embodiment, the driving coil 25 is fixed to the scanning mirror 21 side and the magnet 29 is fixed to the base member 2a side, and a predetermined driving pulse is applied to the driving coil 25 from the control unit 12 to generate electromagnetic force. This is a so-called moving coil drive motor that swings the scanning mirror 21. On the other hand, a so-called moving magnet system in which the magnet 29 and the drive coil 25 are arranged opposite to each other may be used. In addition, the effect of this embodiment described below can be expected even if the drive unit that reciprocally rotates the scanning mirror 21 is combined with any other drive unit.

  The light detection unit 6 is mounted on the base member 2 a and includes a band pass filter 15, a light receiving opening 16, and a light detector 17. Among these, the band pass filter 15 allows the light in the vicinity of the wavelength of the light source to pass through the captured reflected and scattered light, but blocks the other light. The intensity of the reflected / scattered light incident on the photodetector 17 corresponds to a change in the reflectance of the object in scanning, and corresponds to external information in the scanning plane region.

  3A and 3B show the external configuration of the scanning mirror 21 used in the optical scanning module 1 of the present embodiment. FIG. 3A is a diagram showing an external configuration when the scanning mirror is viewed obliquely from the front side, and FIG. 3B is a diagram showing an external configuration when the scanning mirror is viewed from diagonally above the back side. FIG. 4 is a diagram illustrating an external configuration of the scanning mirror viewed from the side.

  The scanning mirror 21 includes a condensing mirror 21a for reading a concave shape having a focal point on the light receiving surface of the photodetector 17, and an exit mirror 21b of a plane mirror for emitting scanning light disposed substantially at the center of the condensing mirror 21a. And are integrally formed. The scanning mirror 21 has a shape in which the cutout portion 30 is cut out so that the lower end corners farthest from the rotation center axis of the mirror surface that is originally rectangular are inclined.

As shown in FIG. 3A, the scanning mirror 21 of the present embodiment has a shape in which both lower corner portions 30 indicated by dotted lines of the scanning mirror 21 having a conventional size are cut out. That is, the lower end corners of the collecting mirror 21a are cut off obliquely.
Below, the shape of the condensing mirror 21 of this embodiment is demonstrated. FIG. 4 is a diagram illustrating an external configuration of the scanning mirror viewed from the side.

  As shown in FIG. 2, the optical scanning module 1 according to the present embodiment includes an emission optical system including a light source unit 3 and a folding mirror 5, a band-pass filter 15, and a light receiving opening 16, as shown in FIG. The light detection unit 6 including the light detector 17 is arranged so as to be stacked on the apparatus side portion. Therefore, in the height direction of the scanning mirror 21, the laser diode as the light source is arranged offset downward with respect to the center in the rotation axis direction. In order to solve this problem, the return mirror 5 positioned in front of the light source has a tilt angle, so that the emitted light is launched toward the plane mirror portion that lies at the approximate center of the scanning mirror.

  In addition, since the exit mirror 21 b has an angle parallel to the folding mirror 5, the launch angle by the folding mirror 5 is canceled and horizontal emission light (scanning light) is emitted from the center of the scanning mirror 21. It is possible to do.

  In this embodiment, as shown in FIG. 4, the concave shape of the condensing mirror 21a of the scanning mirror 21 uses a paraboloid, but it has at least one focal point regardless of whether it is a spherical surface or an aspherical surface. It can be combined with various concave curved surfaces. For the reasons described above, the photodiode as the light receiving unit is offset in the upward direction opposite to the light source unit with respect to the center in the height direction of the scanning mirror.

  Therefore, the focal position P of the condensing mirror 21a having a parabolic surface is also offset upward with respect to the center in the height direction of the scanning mirror, and therefore the scanning mirror 21 is in relation to the center surface in the height direction. It has an asymmetric shape.

  In this way, when the scanning mirror 21 has an asymmetric shape with respect to the center in the height direction Z, and the condensing mirror surface is rectangular, both lower corners located far from the concave focal point are Since it projects as the farthest end with respect to the rotation axis, more space is required when the rotation operation of the scanning mirror 21 is taken into consideration. This becomes a problem when downsizing such as modularization. That is, the conventional optical scanning module described above has a problem.

  In addition, since the scanning mirror 21 has an asymmetric shape in the height direction Z, the principal axis of inertia of the movable parts including the movable members of the scanning mirror 21 and the drive unit 22 is the mass at the farthest end of the scanning mirror 21. As shown in FIG. 5A, the moment of inertia is different between the upper and lower sides of the scanning mirror 21, and a force having an inclination acts on the rotation center axis. This hinders the stability of the swinging motion (linearity: straight-ahead performance passing through the same trajectory in which the forward path and the return path are straight around the rotation axis).

  Therefore, in the present embodiment, the scanning mirror 21 farthest from the rotation center axis is formed in a shape cut off so that both lower corners are inclined. As a result, as shown in FIGS. 3A and 4, in the height direction Z of the scanning mirror 21, the PB direction away from the concave focal point P (B is the XY plane from the focal point P = Z of the scanning mirror outline). The shape of the aperture is such that the outer shape gradually narrows according to the intersection point when a perpendicular is dropped on the central plane in the direction.

  With this shape, as shown in FIG. 5B, the lower end side corners (points farthest from the rotation axis) a, b, c, d of the scanning mirror 21 and the circular orbit locus at the center of the lower end. The difference is smaller than that of the conventional rectangular scanning mirror described above. As a result, in total, the inclination of the inertia principal axis of the moving parts as a whole is effectively improved, and when the scanning mirror 21 is oscillated, the inertia moment is substantially equal above and below the scanning mirror 21, and stable oscillation is achieved. Operation is realized. In addition, since part of the scanning mirror is cut to reduce the weight, the load on the drive unit is reduced and the swinging becomes lighter, and the space required for the swinging can be reduced. This can contribute to downsizing of the apparatus.

  Furthermore, since the cut off lower end side corner is the farthest from the focal point of the collector mirror 21a, the aberration of the concave curved surface is large, and the incident angle to the photodiode is increased, so that the light receiving sensitivity is also lowered and the area is reduced. The signal acquisition performance is poor, and the degradation of the reading performance due to the reduction of the condensing area of the condensing mirror 21a is minimized.

Next, a modification of the first embodiment will be described.
FIG. 6A is a conceptual configuration diagram of the scanning mirror in the modified example viewed from the front, and FIG. 6B illustrates a circular orbit drawn when the lower end of the scanning mirror in the modified example swings. It is the figure which showed the locus | trajectory.

  In the first embodiment described above, the lower end corners of the condensing mirror 21a having the conventional size are cut obliquely, but the reflection area due to the cut portion is reduced. In this modified example, as shown in FIG. 6A, both sides and lower sides of the scanning mirror 21 of the conventional size indicated by the dotted line have both sides and lower sides so as to have oblique sides that pass diagonally through the bottom corners. The scanning mirror 41 has a shape in which a side expansion portion 41a and a lower expansion portion 41b are added to each of the above.

  In this scanning mirror 41, as shown in FIG. 6B, the three sides forming the lower end side of the scanning mirror 41 are formed so that the arc-shaped trajectories drawn during the rotation operation substantially coincide with each other. That is, the four corners formed by the three sides forming the lower end of the scanning mirror 41 are adjusted so as to draw substantially the same circular orbit. Here, “substantially identical” means that the difference between the circular orbit locus at the lower corner (the furthest point from the rotation axis) and the circular orbit locus at the center of the lower end of the scanning mirror is as simple as described in the prior art. It is suggested that it is smaller than the rectangular one.

  Therefore, the scanning mirror 41 of this modification can further enlarge the condensing mirror surface while the space required when the scanning mirror swings is the same space as the conventional rectangular scanning mirror 21. . By increasing the area of the condensing mirror surface, it is possible to improve the condensing capability with respect to the occupied space that must be secured on the base portion 2a, and as a result, it is possible to improve the reading performance.

  In addition, the outer shape of the scanning mirror 41 increases the mass around the upper side of the scanning mirror close to the rotation center axis and does not increase the mass around the lower end corner farthest from the rotation center axis. The inclination of the inertial main shaft of the entire movable part is effectively improved, and a more stable swinging operation can be obtained.

Next, a second embodiment will be described.
FIGS. 7A and 7B show the external configuration of the scanning mirror 21 used in the optical scanning module 1 of the second embodiment. FIG. 7A is a diagram showing an external configuration when the scanning mirror is viewed from diagonally upward on the front side, and FIG. 7B is a diagram showing an external configuration when viewing the scanning mirror from diagonally upward on the back side.
The scanning mirror 51 of the present embodiment is cut into a curve whose lower end is a part of a substantially ellipse. When the scanning mirror swings, if it is considered that the lower end corner draws an arc-shaped trajectory, the necessary space and the light condensing area are theoretically most efficiently achieved by forming the lower end of the scanning mirror into a curve. Is possible.

  Similarly to the first embodiment, the cut lower end side curved portion is a portion farthest from the focal point of the condensing mirror 21a, so that the aberration of the concave curved surface is large and the incident angle to the photodiode is increased. Therefore, since the light receiving sensitivity is low and the signal acquisition performance per area is poor, the degradation of the reading performance due to the reduction of the light collecting area of the light collecting mirror 21a is minimized.

  Therefore, according to the present embodiment, an effect equivalent to that of the first embodiment described above can be obtained. That is, a stable swinging operation is realized, and a part of the scanning mirror is cut to reduce the weight, so the load on the drive unit is reduced and the swinging becomes light, and the space required for the swinging By reducing the size of the device, it is possible to reduce the size of the device.

Next, a third embodiment will be described.
FIGS. 8A and 8B are views showing an external configuration of the scanning mirror according to the third embodiment as viewed from the side.

  In the present embodiment, the thickness of the scanning mirror is changed to reduce the difference in the moment of inertia generated at the upper and lower ends of the scanning mirror that occurs when the scanning mirror is swung. The first and second embodiments described above are examples in which both lower ends of the scanning mirror are cut obliquely.

  In the present embodiment, as shown in FIG. 8A, when the scanning mirror 52 is viewed from the side surface, the distance from the rotating shaft 24, in this case, the thickness of the mirror lower end 52a is reduced. . In a normal mold mirror, it is recommended that the plate thickness of the scanning mirror be uniform, but the plate thickness is reduced within a range that does not adversely affect the surface accuracy and wavefront aberration of the optical surface.

  Further, for the purpose of reducing the weight of the scanning mirror, the mirror upper end 52b may be made slightly thinner in addition to the mirror lower end 52a of the scanning mirror 52, as shown in FIG. In this case, of course, it is a range that does not adversely affect the surface accuracy and wavefront aberration of the optical surface, and it is necessary to reduce the difference between the moments of inertia generated at the upper and lower ends of the scanning mirror that occurs at the time of swinging. .

  Therefore, according to the present embodiment, an effect equivalent to that of the first embodiment described above can be obtained. That is, a stable swinging operation is realized, the weight of the scanning mirror is reduced, the load on the drive unit is reduced, the swinging becomes lighter, and the space required for the swinging is reduced, thereby reducing the device. Downsizing can be realized. Furthermore, according to this embodiment, since the condensing area of the condensing mirror is not reduced, reading performance does not deteriorate.

  Since the scanning mirror according to the first, second, and third embodiments and the modification described above is a mirror part having a complicated curved surface or curve, the manufacturing method thereof is formed as a resin part by injection molding. A mold mirror in which a reflection film forming process such as Au coating or Ai coating is applied to the surface of the resin component is preferable.

According to each embodiment and modification described above, the optical scanning module of the present invention can obtain the following effects.
1. The required space can be reduced when the scanning mirror rotating operation is taken into consideration.
2. The inclination of the principal axis of inertia of the entire movable part is improved, and the rotation operation is further stabilized.
3. When compared on the premise of the same exclusive space, it is possible to mount a condensing mirror portion having a surface covering larger than that of a simple rectangular shape, so that reading performance can be improved.
4). Even when compared with a large rectangle that does not have a diaphragm at the lower end of the mirror, the removed peripheral portion of the lower end corner is far away from the focal point of the condensing mirror part, so that the aberration of the concave curved surface is large, leading to the PD. Since the light receiving sensitivity is low due to the large incident angle, it can be said that the signal acquisition performance per area is poor, and therefore the degradation of the reading performance due to the reduction of the condensing area of the condensing mirror portion can be minimized.
5). As a driving method of the scanning mirror, a driving unit that swings (reciprocates) a driving unit movable member supported by a shaft sliding method by a moving coil type electromagnetic driving device can be used. Further, a moving magnet type drive unit that reciprocally rotates around a virtual rotation axis by a known elastic leaf spring support system may be used. That is, the same effect can be expected even when combined with any other driving means that reciprocally rotates the scanning mirror.

FIG. 1 is a perspective view showing an external configuration of the optical scanning module according to the first embodiment. FIG. 2 is a diagram illustrating a configuration of the optical scanning module in a state in which the upper lid of the optical scanning module according to the first embodiment is removed. FIG. 3A is a diagram illustrating an external configuration of the scanning mirror as viewed obliquely from the front side. FIG. 3B is a diagram showing an external configuration of the scanning mirror as viewed obliquely from the back side. FIG. 4 is a diagram illustrating an external configuration of the scanning mirror viewed from the side. FIG. 5A is a diagram showing a trajectory that becomes a swing range in a conventional rectangular scanning mirror. FIG. 5B is a diagram illustrating a trajectory serving as a swing range in the scanning mirror according to the embodiment. FIG. 6A is a diagram illustrating a conceptual configuration of the scanning mirror according to the modification of the first embodiment as viewed from the front. FIG. 6B is a diagram showing a trajectory of a circular orbit drawn when the lower end of the scanning mirror swings in the modified example. FIG. 7A is a diagram illustrating an external configuration of a scanning mirror used in the optical scanning module according to the second embodiment when viewed obliquely from the front side. FIG. 7B is a diagram showing an external configuration when the scanning mirror is viewed obliquely from the back side. FIGS. 8A and 8B are views showing an external configuration of the scanning mirror according to the third embodiment as viewed from the side.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical scanning module, 2 ... Housing, 2a ... Base member, 2b ... Substrate unit, 2c ... Support member, 2d ... Screw, 3 ... Light source unit, 4 ... Optical scanning device, 5 ... Folding mirror, 6 ... Light detection unit , 11 ... Connector, 12 ... Control part, 15 ... Band pass filter, 16 ... Light receiving opening, 17 ... Photodetector, 21 ... Scanning mirror, 21a ... Condensing mirror, 21b ... Output mirror, 22 ... Drive part, 23 DESCRIPTION OF SYMBOLS ... Bearing part, 24 ... Rotating shaft, 25 ... Drive coil, 26 ... Leaf spring, 27 ... Support spring holding member, 28 ... Leaf spring, 29 ... Magnet, 30 ... Notch part.

Claims (5)

A laser light source that emits laser light, a scanning mirror that reflects the laser light to irradiate the object to be read, a mirror drive that swings the scanning mirror in one direction, and is reflected by the object to be read A light receiving module that photoelectrically converts the returned light, and an optical scanning module comprising:
The scanning mirror is integrally formed with a plane mirror portion for emission and a condensing mirror portion for reading having a concave shape with a focal point at the position of the light receiving portion,
Further, the shape of the scanning mirror is narrowed so that the trajectories during rotation of the sides forming the end portion far from the focal point of the scanning mirror substantially coincide with each other when viewed from the rotation axis direction of the scanning mirror. An optical scanning module that is adjusted to A laser light source that emits laser light, a scanning mirror that reflects the laser light to irradiate the object to be read, a mirror drive that swings the scanning mirror in one direction, and is reflected by the object to be read A light receiving module that photoelectrically converts the returned light, and an optical scanning module comprising:
The scanning mirror is integrally formed with a plane mirror portion for emission and a condensing mirror portion for reading having a concave shape with a focus at the position of the light receiving portion, and further, the outer shape of the scanning mirror .., An, and a perpendicular drawn from the vertex Ai (i: integer) to the rotation axis is a line segment AiOi, so that at least three line segments AiOi substantially coincide with each other. An optical scanning module, wherein an outer shape of a scanning mirror is adjusted.   When a perpendicular line PB is drawn from the focal point P of the condensing mirror portion to a plane that passes through the center of the scanning mirror outline in the rotation axis direction and is perpendicular to the rotation axis, the outline of the scanning mirror becomes narrower in the PB direction. 3. The optical scanning module according to claim 1, wherein the outer shape of the scanning mirror is adjusted so as to have a portion.   4. The optical scanning according to claim 3, wherein the outer shape of the scanning mirror is adjusted so that the principal axis of inertia of the entire movable part including the scanning mirror and the driving part movable member is substantially parallel to the rotation center axis. module.   5. The scanning mirror is an injection-molded part made of resin, and the outer shape of the scanning mirror is adjusted so that the plate thickness of the scanning mirror becomes thinner toward the PB direction. Optical scanning module.

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