Mirror actuator and beam irradiation device

A mirror actuator includes a turning axis for turning a mirror; a support section for supporting the turning axis so as to be capable of turning; and a sliding contact member that is arranged on the turning axis and is opposed to the support section in a direction parallel to the turning axis with a predetermined clearance from the support section. The turning axis is biased in one direction parallel to the turning axis. This biasing causes the sliding contact member to contact the support section.

This application claims priority under 35 U. S. C. Section 119 of Japanese Patent Applications No. 2009-272843 filed Nov. 30, 2009, entitled “MIRROR ACTUATOR AND BEAM IRRADIATION DEVICE” and No. 2010-185219 filed Aug. 20, 2010, entitled “MIRROR ACTUATOR AND BEAM IRRADIATION DEVICE”. The disclosure of the above applications is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mirror actuator that turns a mirror around two shafts as turning axes and a beam irradiation device equipped with such a mirror actuator.

2. Disclosure of Related Art

In recent years, laser radars have been mounted on family cars and others for enhancement of driving safety. The laser radar generally scans a target area with laser light and detects the presence or absence of any obstacle at each scan position, depending on whether there is any reflected light at each scan position. In addition, the laser radar detects a distance from an obstacle, based on an amount of time required between the instant when laser light is irradiated and the instant when reflected light is received at each scan position. The laser radar is provided with an actuator for scanning a target area with laser light.

Such an actuator may be a mirror actuator that turns a mirror around two shafts as turning axes, for example. On the mirror actuator, laser light enters the mirror in an oblique direction. When the mirror is turned horizontally and vertically around the two shafts as turning axes, the laser light is distributed horizontally and vertically in a target area.

Such a mirror actuator has clearances parallel to the two turning axes between the two turning axes and support sections supporting the turning axes. Accordingly, even if the support sections are deformed by heat or the like, it is possible to avoid the support section from being strongly pressed against the ends of the turning axes. This allows the turning axes to turn stably.

However, if these clearances are provided, when the mirror is driven and turned, the ends of the turning axes move toward the support sections and collide against the support sections. On the laser radar, the mirror turns at a high speed and in a short cycle, and therefore the turning axes repeatedly collide against the support sections in a short cycle while the mirror is driven. The repeated collisions generate noise. In addition, the collisions make small repeated impacts on the actuator, which may deteriorate the properties of the actuator.

SUMMARY OF THE INVENTION

A first aspect of the present invention relates to a mirror actuator. The mirror actuator in the first aspect includes a turning axis for turning a mirror; a support section for supporting the turning axis so as to be capable of turning; a sliding contact member that is arranged on the turning axis and is opposed to the support section in a direction parallel to the turning axis with a predetermined clearance from the support section; and a biasing arrangement that biases the turning axis in one direction parallel to the turning axis to thereby cause the sliding contact member to contact the support section.

A second aspect of the present invention relates to a beam irradiation device. The beam irradiation device in the second aspect includes a mirror actuator in the first aspect and a laser light source that supplies laser light to the mirror of the mirror actuator.

However, the drawings are only for purpose of description, and do not limit the scope of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

In this embodiment, a tilt unit110and a pan unit120are equivalent to a “moving section” recited in the claims; a support shaft111is equivalent to a “turning axis” recited in the claims; tilt coils113are equivalent to a “coil” recited in the claims; an shaft bearing116a, a yoke141, and concave sections141bare equivalent to a “support section” recited in the claims; poly slider washers118and a rubber washer118aare equivalent to a “sliding contact member” recited in the claims; the shaft bearing116a, an E ring117a, a ring-shaped magnet119, and magnets132are equivalent to a “biasing arrangement” recited in the claims; the E ring117ais equivalent to a “magnetic member” recited in the claims; the rubber washer118ais equivalent to a “buffer member” recited in the claims; the E ring117ais equivalent to a “stopper member” recited in the claims; and a laser light source401is equivalent to a “laser light source” recited in the claims. However, the foregoing correspondences between the claims and this embodiment are shown as merely examples, and the claims are not limited to by this embodiment.

FIG. 1is an exploded perspective view of a mirror actuator100in this embodiment.

The mirror actuator100includes the tilt unit110, the pan unit120, a magnet unit130, a yoke unit140, a mirror150, and a transmissive plate200.

The tilt unit110includes the support shaft111, a tilt frame112, and two tilt coils113. The support shaft111has on a middle part thereof a hole111apenetrating in an up-down direction and a hole111bpenetrating the hole111afrom the front side. In addition, the support shaft111has two screw holes111cpenetrating from front to back and two grooves111dnear both ends thereof.

The tilt frame112has on sides thereof coil attachment sections112afor attachment of the tilt coils113. In addition, the tilt frame112has two holes112bpenetrating from front to back at positions in alignment with the screw holes111cof the support shaft111.

When the two screw holes111cof the support shaft111are opposed to the two holes112bof the tilt frame112, the two screws115are screwed into the screw holes111cthrough the holes112bfrom the back, whereby the support shaft111is attached to the tilt frame112. Then, when the tilt coils113are attached from the right and left sides to the coil attachment sections112aof the tilt frame112, the tilt unit110is completely assembled as shown inFIG. 2A.FIG. 2Ashows the support shaft111to which the shaft bearings116aand116b, the E rings117aand117b, and the three poly slider washers118are attached.

The pan unit120is attached to the assembled tilt unit110as described later. Subsequently, the tilt unit110is attached to the yoke141with the use of the shaft bearings116aand116b, the E rings117aand117b, the poly slider washers118, and a shaft fixing member142, as described later.

Returning toFIG. 1, the pan unit120includes a pan frame121, a support shaft122, and a pan coil123. The pan frame121has an upper plate121band a lower plate121cwith a concave section121atherebetween. The upper plate121band the lower plate121chave holes121darranged one above the other through which the support shaft122passes. In addition, the upper plate121band the lower plate121chave on front sides thereof stair sections121einto which the mirror150is fitted. Further, the lower plate121chas a leg121fextending downward. The leg121fhas a concave section121ginto which the transmissive plate200is fitted. The pan frame121has on a rear side thereof a coil attachment section (not shown) to which the pan coil123is attached.

The support shaft122has a screw hole122apenetrating from front to back, and grooves122band122cabove and below the screw hole122a. The support shaft122has a balancer122dattached to an upper end thereof. A distance between the two grooves122band122cis made shorter than a distance between an inner surface of the upper plate121band an inner surface of the lower plate121cin the pan frame121.

The magnet unit130includes a frame131, two pan magnets133, and eight tilt magnets132. The frame131is configured to have a concave section131aon a front side thereof. An upper plate131bof the frame131has two notches131cformed from front to back, and has a screw hole131din a middle part of the frame131. The eight magnets132are attached in two upper and lower lines to side inner surfaces of the frame131. In addition, the two magnets133are attached to the inner surface of the frame131in such a manner as to be tilted in an anteroposterior direction as shown in the figure.

The yoke unit140includes the yoke141and the shaft fixing member142. The yoke141is formed by a magnetic member. The yoke141has walls141aon sides thereof. The walls141ahave on lower ends thereof concave sections141bfor attachment of the support shaft111of the tilt unit110. The yoke141has on an upper side thereof two screw holes141cpenetrating in an up-down direction. Further, the yoke141has on the upper side thereof a hole141dvertically penetrating at a position in alignment with the screw hole131dof the magnet unit130. A distance between inner surfaces of the two walls141ais made longer than a distance between the two grooves111dof the support shaft111.

The shaft fixing member142is a metallic thin plate member with flexibility. The shaft fixing member142has plate springs142aand142bon a front side thereof. The plate springs142aand142bhave at lower ends thereof receiving sections142cand142d, respectively, for preventing the shaft bearings116aand116bof the tilt unit110from dropping off. In addition, the shaft fixing member142has on an upper side thereof holes142eat positions in alignment with the two screw holes141cof the yoke141. Further, the shaft fixing member142has on the upper side thereof a hole142fat a position in alignment with the hole141dof the yoke141.

At assembly of the mirror actuator100, the tilt unit110is first assembled as shown inFIG. 2A. Then, the pan unit120is attached to the support shaft111of the tilt unit110as described below.

First, the shaft bearings124aand124bare fitted and fixed from the concave section121aside into the holes121din the upper plate121band the lower plate121cof the pan frame121, respectively. Then, the pan coil123is attached to the rear side of the pan frame121. Further, the transmissive plate200is fitted into the concave section121gof the pan frame121, and then the transmissive plate200is fixed to the leg121fof the pan frame121with a transmissive plate fixing bracket201.

After that, the tilt frame112and the support shaft111are inserted into the concave section121aof the pan frame121. Then, the hole111aof the support shaft111and the shaft bearings124aand124bof the pan frame121are aligned in an up-down direction. In this state, the support shaft122is passed from the top through the hole111aand the shaft bearings124aand124b. At that time, the three poly slider washers125are put on the support shaft122in the concave section121a. Further, the hole111bof the support shaft111is aligned with the screw hole122aof the support shaft122, and then the screw114is screwed from the front side through the hole111binto the screw hole122a. Accordingly, the support shaft122is fixed to the support shaft111.

Subsequently, the pan frame121is slid in such a manner that the three poly slider washers125are positioned under the lower groove122cof the support shaft122, and then the E ring126bis fitted into the lower groove122c. Further, the upper groove122bof the support shaft122is positioned within the concave section121a, and then the E ring126ais fitted into the upper groove122b. Accordingly, the pan unit120is attached to the tilt unit110as shown inFIG. 2B. In this state, the pan frame121is capable of turning around the support shaft122and capable of moving slightly in an up-down direction along the support shaft122.

After the pan unit120is attached as described above, the mirror150is fitted and fixed into the stair sections121eof the pan frame121. After that, the shaft bearings116aand116battached to the both ends of the support shaft111in the tilt unit110are fitted into the concave sections141aand141bof the yoke141shown inFIG. 1. Then, in this state, the shaft fixing member142is attached to the yoke141such that the shaft bearings116aand116bdo not drop off the concave sections141band141b, respectively. Specifically, the shaft fixing member142is attached to the yoke141in such a manner that the receiving section142csupports the shaft bearing116afrom below and the receiving section142dpinches the shaft bearing116bfrom the front side. In this state, the two screws143are screwed into the screw holes141cof the yoke141through the two holes142e. Accordingly, the structure shown inFIG. 2Bis attached to the yoke unit140.

This way, the structure shown inFIG. 3Ais completely assembled. In this state, the tilt frame112is capable of turning around the support shaft111integrally with the pan frame121, and is capable of moving slightly in a right-left direction along the support shaft111.

As described above, the support shaft111is attached at the both ends to the concave sections141bof the yoke141by the shaft fixing member142so as to be capable of elastic displacement.FIG. 4Ais a cross-section view ofFIG. 4Ctaken along A-A′, andFIG. 4Bis a cross-section view ofFIG. 4Ctaken along B-B′. As shown in an enlarged view ofFIG. 4B, the concave section141bis configured to have two straight line sections L1, two straight line sections L2inclined at a specific angle from the straight line sections L1, and a curved section L3linking the two straight line sections L2. A width W between the two straight sections L1is approximately identical to an outer diameter of the shaft bearings116aand116b. Both of the two concave sections141bon the yoke141have the shape as described above.

When the two shaft bearings116aand116bare inserted from below into the corresponding concave sections141b, the two straight sections L1and the two straight sections L2are brought into contact with outer circumferences of the shaft bearings116aand116b, respectively. At that time, the curved sections L3do not contact the shaft bearings116aand116b. In this state, the shaft bearing116ais pressed upward by a retainer plate B of the receiving section142c, as shown inFIG. 4B. Accordingly, the shaft bearing116bis attached to the concave section141b.

Although not shown inFIG. 4A, the shaft bearing116bis also attached to the concave section141bin the same manner as described above. As shown in an enlarged view ofFIG. 4A, the receiving section142dhas also a retainer plate B for pressing the shaft bearing116bupward. The shaft bearing116bis pressed upward by this retainer plate B.

The both ends of the support shaft111are not firmly fixed to the concave sections141band are capable of elastic displacement because the retainer plates B are capable of elastic deformation. Since the support shaft111can be elastically displaced at the both ends, the support shaft111can be attached smoothly to the concave sections141beven if the support shaft111is formed with any error in shape or the concave sections141bare formed with any error in shape and arrangement. In addition, the support shaft111can be rotated without problems.

The thus assembled structure ofFIG. 3Ais attached to the magnet unit130in such a manner that the two walls141aof the yoke141are inserted into the notches131cof the frame131in the magnet unit130. Then, in this state, the screw144is screwed into the screw hole131dof the magnet unit130through the hole142fof the shaft fixing member142and the hole141dof the yoke141. Accordingly, the structure ofFIG. 3Ais attached and fixed to the magnet unit130. This way, the mirror actuator100is completely assembled as shown inFIG. 3B.

In the assembled state shown inFIG. 3B, when the pan frame121turns around the support shaft122as a turning axis, the mirror150turns accordingly. In addition, when the tilt frame112turns around the support shaft111as a turning axis, the pan unit120turns accordingly, and the mirror150also turns integrally with the pan unit120. In this manner, the mirror150is supported so as to be capable of turning by the mutually orthogonal support shafts111and122. Further, the mirror150also turns around the support shafts111and122when the tilt coils113and the pan coil123are energized. At that time, the transmissive plate200attached to the pan unit120turns together with the turning of the mirror150.

A balancer122dis intended to adjust the structure shown inFIG. 2Bto turn around the support shaft111in a well-balanced manner. The balance of the turning is adjusted by the weight of the balancer122d. Besides, if the balancer122dcan be vertically displaced, the balance of the turning can be adjusted by fine-tuning the lower position of the balancer122d.

In the assembled state ofFIG. 3B, the eight magnets132are adjusted in layout and polarity so as to allow the tilt frame112to generate a turning force around the support shaft111by applying electricity to the tilt coils113. Therefore, when electricity is applied to the tilt coils113, the tilt frame112turns around the support shaft111by an electromagnetic driving force generated on the tilt coils113. With the turning of the tilt frame112, the mirror150and the transmissive plate200turn accordingly.

In addition, in the assembled state ofFIG. 3B, the two magnets133are adjusted in layout and polarity so as to allow the pan frame121to generate a turning force around the support shaft122by applying electricity to the pan coil123. Therefore, when electricity is applied to the pan coil123, the pan frame121turns around the support shaft122by an electromagnetic driving force generated on the pan coil123. With the turning of the pan frame121, the mirror150and transmissive plate200turn accordingly.

In the mirror actuator100of this embodiment, the support shaft111is movable in a right-left direction. Accordingly, even if the yoke141is deformed due to a temperature change to alter the degree of tilt (opening) of the two walls141aof the yoke141, it is possible to turn the support shaft111smoothly without applying an undesired force to the support shaft111in a right-left direction. From the same viewpoint, the support shaft122is also movable in an up-down direction. In particular, if the mirror actuator100is mounted on an in-vehicle laser radar, the support shafts111and122need to be movable because of larger temperature changes.

However, if the support shaft111is movable in a right-left direction as described above, when the mirror150is driven and turned in a right-left direction (pan direction), the ends of the support shaft111move in a right-left direction and collide against the shaft bearings116aand116b. If the mirror actuator100is mounted on a laser radar, the mirror150turns in the pan direction at a high speed and in a short cycle. Accordingly, while the mirror150is driven, the support shaft111repeatedly collides against the shaft bearings116aand116bin a short cycle. Such repeated collisions cause noise and may deteriorate the properties of the actuator100. Meanwhile, the support shaft122is less prone to cause such collision under a downward force by gravity.

Accordingly, in this embodiment, only the right E ring117ais formed by a magnetic material. The left E ring117bis formed by a nonmagnetic material.

FIGS. 5A and 5Bare diagrams for describing an advantage of configuring the E rings117aand117bin such a manner.FIG. 5Ais a front view of the mirror actuator100, andFIG. 5Bis an enlarged view of a part shown by a dashed line inFIG. 5A.

When only the right E ring117ais formed by a magnetic material as described above, a magnetic force is generated between the E ring117aand the right magnet132of the magnet unit130. This magnetic force biases the support shaft111to the right. On occurrence of this biasing, the poly slider washers118are pressed by the E ring117aagainst the shaft bearing116a. This prevents the support shaft111from moving in a right-left direction when the mirror150is turned in the pan direction. Accordingly, it is possible to suppress noise generation as described above and prevent the mirror actuator100from being deteriorated in properties due to collision of the support shaft111.

The three poly slider washers118are interposed between the E ring117aand the shaft bearing116a. Accordingly, the support shaft111can turn smoothly even if being biased as described above. Therefore, the mirror150can be favorably turned in an up-down direction (tilt direction).

FIGS. 6,7A, and7B are diagrams showing a configuration of a beam irradiation device with the mirror actuator100.

FIG. 6is a diagram showing a scanning optical system. InFIG. 6, reference numeral500denotes a base, and the base500has a horizontal top surface. The base500has an opening503aat a mounting position of the mirror actuator100. The mirror actuator100is attached to the base500such that the transmissive plate200is inserted into the opening503a. The mirror actuator100is attached to the base500, such that the up-down direction shown inFIG. 1corresponds to the vertical direction shown inFIGS. 4A to 4C.

The base500has on the top surface thereof a laser light source401and beam shaping lenses402and403. The laser light source401is attached to a laser light source substrate401aon the top surface of the base500.

Laser light emitted from the laser light source401(hereinafter, referred to as “scanning laser light”) is subjected to convergence in horizontal and vertical directions by the lenses402and403, respectively. The lenses402and403are designed such that a beam has a predetermined size (about 2 m long and 1 m wide, for example) in a target area (which is set at a position of about 100 m forward of a beam window of the beam irradiation device, for example).

The lens402is a cylindrical lens having a lens effect in a vertical direction. The lens403is an aspherical lens to make scanning laser light approximately parallel. Beams emitted from the laser light source have different spread angles in vertical and horizontal directions. The first lens402changes a ratio of spread angles of laser light in vertical and horizontal directions. The second lens403changes magnifications of spread angles of emitted beams (both in vertical and horizontal directions).

The scanning laser light having passed through the lenses402and403enters the mirror150of the mirror actuator100, and is reflected by the mirror150toward a target area. When the mirror150is biaxially driven by the mirror actuator100, the target area is scanned with the scanning laser light.

The mirror actuator100is arranged in such a manner that, when the mirror150is in a neutral position, the scanning laser light from the lens403enters a mirror surface of the mirror150at an incident angle of 45 degrees in a horizontal direction. The “neutral position” refers to a position of the mirror150in which the mirror surface is parallel to a vertical direction and the scanning laser light enters the mirror surface at an incident angle of 45 degrees in a horizontal direction.

The base500has a circuit board300on a bottom surface thereof. The base500also has circuit boards301and302on rear and side surfaces thereof.

FIG. 7Ais a partial planar view of the base500as seen from the underside.FIG. 7Ashows a servo optical system and peripheral arrangements of the same arranged on the underside of the base500.

As shown in the figure, walls501and502are formed around the underside of the base500. A central area from the walls501and502has a planar surface503that is lower by one level than the walls501and502. The wall501has an opening for attachment of a semiconductor laser303. The circuit board301with the semiconductor laser303is attached to an outer surface of the wall501so that the semiconductor laser303is inserted to the opening. Meanwhile, the circuit board302with a PSD308is attached near the wall502.

A condenser lens304, an aperture305, and a neutral density (ND) filter306are attached by a mounting bracket307to the planar surface503on the underside of the base500. Further, the planar surface503has the opening503aas described above. The transmissive plate200attached to the mirror actuator100projects to the underside of the base500through the opening503a. Here, the transmissive plate200is positioned in such a manner that, when the mirror150of the mirror actuator100is in the neutral position, the two planar surfaces are parallel to a vertical direction and are tilted at an angle of 45 degrees relative to an outgoing light axis of the semiconductor laser303.

Laser light emitted from the semiconductor laser303(hereinafter, referred to as “servo light”) passes through the condenser lens304, and then is reduced in beam diameter by the aperture305. The servo light is further attenuated by the ND filter306. After that, the servo light is entered into the transmissive plate200and subjected to refraction by the transmissive plate200. Then, the servo light having passed through the transmissive plate200is received by the PSD308. The PSD308outputs a position detection signal in accordance with a light-receiving position.

FIG. 7Bis a diagram showing schematically a relationship between a turning position of the transmissive plate200and a path of the servo light. For the sake of simplicity,FIG. 7Billustrates only the transmissive plate200, the semiconductor laser303, and the PSD308ofFIG. 5A.

The servo light is refracted by the transmissive plate200tilted relative to the laser light axis, and then is received by the PSD308. Here, when the transmissive plate200turns as shown by a dashed arrow inFIG. 7B, the path of the servo light changes as shown by a dotted line inFIG. 7B, and the receiving position of the servo light on the PSD308changes accordingly. Therefore, the turning position of the transmissive plate200can be determined by the receiving position of the servo light detected by the PSD308. The turning position of the transmissive plate200corresponds to the scanning position of the scanning laser light in the target area. Therefore, the scanning position of the scanning laser light in the target area can be detected in accordance with a signal from the PSD308.

According to this embodiment as described above, the movement of the support shaft111in an axial direction can be suppressed by a magnetic force between the E ring117aand the right magnet132of the magnet unit130. Accordingly, it is possible to prevent that the support shaft111collides against the shaft bearings116aand116bduring mirror driving. Therefore, it is possible to suppress noise generation by such collision and prevent the mirror actuator100from being deteriorated in properties due to such collision.

In addition, according to this embodiment, the support shaft111is biased by the magnets132for driving the tilt unit110. This allows the mirror actuator100to be simplified in structure as compared with the case of providing an additional biasing arrangement. Further, the E ring117ais formed by a magnetic material so as to generate a magnetic force between the E ring117aand the magnet132. Therefore, it is possible to simplify the structure as compared with the case of providing an additional magnetic member.

In this embodiment, the magnetic member is arranged on the support shaft111to generate a magnetic force between the magnetic member and the magnet132. Alternatively, the magnetic member may be arranged at another position such as the tilt frame112or the pan frame121to bias the support shaft111in one direction. In addition, a magnet may be arranged in place of the magnetic member.

Although the embodiment of the present invention is as described above, the present invention is not limited to by the embodiment. Besides, the embodiment of the present invention can be further modified in various manners other than those described above.

MODIFICATION EXAMPLE 1

FIGS. 8A and 8Bare diagrams showing a configuration of a modification example.FIG. 8Ais an exploded perspective view of the tilt unit110.FIG. 8Bis an enlarged view of a right end and its neighboring portion of the support shaft111in the tilt unit110assembled into the mirror actuator100.

In the modification example 1, out of the three poly slider washers118, the middle one is replaced by a rubber washer118a. According to this configuration, even if, during mirror driving, the support shaft111moves to the left against a magnetic force between the E ring117aand the magnet132and then the support shaft111moves again to the right and collides against the shaft bearing116a, the impact of the collision is absorbed by the rubber washer118a. Accordingly, even if the support shaft111moves in such a manner as described above, it is possible to suppress generation of noise and property deterioration of the mirror actuator100due to the collision of the support shaft111.

MODIFICATION EXAMPLE 2

FIG. 9is a diagram showing a modification example of the mirror actuator100. The same components as those of the configuration shown inFIG. 1are given the same reference numerals as those in the configuration ofFIG. 1. The modification example 2 is different from the foregoing embodiment, in the way of attaching the support shaft111to the tilt frame112and the way of attaching the pan frame121to the tilt frame112. Accordingly, the modification example has additional components112c,112d,112e, and112f.

As in the foregoing embodiment, the support shaft111including at both ends thereof the shaft bearings116aand116b, the E rings117aand117b, and the poly slider washers118, is fitted into the groove112cformed in the tilt frame112, and attached and fixed to the tilt frame112. The tilt frame112has two vertically arranged holes112dinto which the shaft bearings112eare fitted from above and below. Accordingly, the tilt unit110is completely assembled as shown inFIG. 10A.

Subsequently, the tilt frame112is placed into the concave section121aof the pan frame121. Then, the pan frame121is positioned in such a manner the two shaft bearings112eand the holes121dof the pan frame121are vertically aligned. In that state, the support shaft122is inserted into the two shaft bearings112eand the holes121dof the pan frame121. At that time, the three poly slider washers112fare interposed between the upper shaft bearing112eand the upper plate121bof the pan frame121. Then, the poly slider washers112fare put on the shaft bearing122. After that, the shaft bearing122is fixed to the pan frame121with an adhesive. Accordingly, a structure is formed as shown inFIG. 10B.

Subsequently, the support shaft111is attached to the yoke141as in the foregoing embodiment, to form a structure shown inFIG. 11A. Further, the structure shown inFIG. 11Ais attached to the magnet unit130as in the foregoing embodiment, to complete the mirror actuator100shown inFIG. 11B.

In this modification example, with regard to the two E rings117aand117battached to the support shaft111, the right E ring117ais formed by a magnetic material and the left E ring117bis formed by a non-magnetic material. Accordingly, the support shaft111is biased to the right by a magnetic force between the E ring117aand the right magnet132, thereby suppressing the movement of the support shaft111during mirror driving, as in the foregoing embodiment. Therefore, this modification example also makes it possible to prevent noise generation and property deterioration of the mirror actuator100due to collision of the support shaft111, as in the foregoing embodiment.

MODIFICATION EXAMPLE 3

FIG. 12is a diagram showing another modification example of the mirror actuator100. InFIG. 12, the same components as those of the configuration shown inFIG. 1are given the same reference numerals as those in the configuration ofFIG. 1.

In the modification example 3, the shaft bearing116ais formed by a magnetic member. Further, the ring-shaped magnet119is sandwiched between the E ring117aand the poly slider washers118. The ring-shaped magnet119is attached to the support shaft111in such a manner that support shaft111passes through a hole of the ring-shaped magnet119.

The E ring117ais formed by a magnetic member, as in the foregoing embodiment.

An outer diameter of the ring-shaped magnet119is approximately identical to an outer diameter of the E ring117a. Since the E ring117ais formed by a magnetic member, the E ring117aand the ring-shaped magnet119are stuck to each other by area contact by a magnetic force. In addition, the E ring117ais fitted into the groove111dof the support shaft111so as to be integrated with the support shaft111. Accordingly, when the ring-shaped magnet119moves in an axial direction of the support shaft111, the support shaft111moves accordingly.

FIGS. 13A and 13Bare diagrams for describing an advantage of the modification example 3.

In the modification example 3, since the shaft bearing116ais formed by a magnetic member, a magnetic force is generated between the shaft bearing116aand the ring-shaped magnet119by which the two components attract each other. Since the shaft bearing116ais fixed with the shaft fixing member142, the ring-shaped magnet119is biased toward the shaft bearing116aby this magnetic force. When the ring-shaped magnet119is biased in this way, the support shaft111is biased to the right via the E ring117aas described above. At that time, the poly slider washers118are pressed toward the shaft bearing116a, that is, to the right.

Accordingly, when the mirror150is turned in the pan direction, it is possible to suppress the movement of the support shaft111in a right-left direction and therefore prevent collision of the support shaft111against the shaft bearings116aand116b. This makes it possible to prevent noise generation and property deterioration of the mirror actuator100due to such collision.

According to the modification example 3, the distance between the ring-shaped magnet119and the shaft bearing116ais made short. Therefore, a larger axial bias can be applied to the support shaft111as compared with the case of the foregoing embodiment. This makes it possible to prevent the movement of the support shaft111during mirror driving in a more reliable manner as compared with the case of the foregoing embodiment. Therefore, it is possible to prevent noise generation and property deterioration of the mirror actuator100due to collision of the support shaft111.

In the configuration of the modification example 3, the middle one of the three poly slider washers118may be replaced by a rubber washer, as in the modification example 1. According to this configuration, even if, during mirror driving, the support shaft111moves to the left against a magnetic force between the ring-shaped magnet119and the shaft bearing116aand then the support shaft111moves again to the right and collides against the shaft bearing116a, the impact of the collision is absorbed by the rubber washer. Accordingly, even if the support shaft111moves in such a manner, it is possible to prevent noise generation and property deterioration of the mirror actuator100due to the collision of the support shaft111.

In addition, as shown inFIG. 14, the configuration of the modification example 3 may be applied to the mirror actuator in the modification example 2 (refer toFIG. 9). InFIG. 14, the shaft bearing116ais formed by a magnetic member in the configuration of the modification example 2. Further, the ring-shaped magnet119is positioned between the E ring117aand the poly slider washers118. The ring-shaped magnet119is attached to the support shaft111in such a manner that the support shaft111passes through the hole of the ring-shaped magnet119. In this configuration, the E ring117ais formed by a magnetic member as in the modification example 2. InFIG. 14, the same components as those of the configuration shown inFIG. 9are given the same reference numerals as those in the configuration ofFIG. 9.

In this configuration example, the support shaft111is biased to the right by a magnetic force acting between the ring-shaped magnet119and the shaft bearing116a, thereby preventing the movement of the shaft111during mirror driving. Accordingly, in this configuration example, it is possible to prevent noise generation and property deterioration of the mirror actuator100due to the collision of the support shaft111, as in the foregoing embodiment.

In the modification example 3, the ring-shaped magnet119and the E ring117aare stuck to each other by a magnet force, whereby the support shaft111and the ring-shaped magnet119are integrated. Alternatively, the ring-shaped magnet119may be attached to and integrated with the support shaft111with an adhesive or the like. In particular, if the E ring117ais not formed by a magnetic material, the ring-shaped magnet119is integrally attached to the support shaft111with an adhesive or the like.

OTHERS

The foregoing embodiment employs a semiconductor laser as a servo light source, but a light emitting diode (LED) may be used instead.

Further, the transmissive plate200is used to change the traveling direction of servo light in the foregoing embodiment. Alternatively, a servo mirror instead of the transmissive plate may be attached to the lower end of the pan unit120to reflect servo light, thereby changing the traveling direction of the servo light. Besides, a light source emitting servo light may be arranged at the lower end of the pan unit120.

In addition, although only the support shaft111is biased by a magnetic force in the foregoing embodiment, the support shaft122may also be biased in an axial direction.

Besides, the embodiment of the present invention can be appropriately modified in various manners within the scope of technical ideas shown in the claims.