Patent Description:
For example, a rotation drive actuator is used in a scanner in a multifunction peripheral, a laser beam printer and other apparatuses. Specifically, a rotary reciprocating drive actuator changes a reflection angle of a laser beam by rotating a mirror of the scanner in a reciprocating manner to realize optical scanning with respect to an object.

Conventionally, the scanner using a galvanometer motor as this type of the rotary reciprocating drive actuator is disclosed in such as PTL <NUM>. Various types of the galvanometer motor, such as a coil movable type in which a coil is attached to the mirror and a structure disclosed in PTL <NUM>, are known.

PTL <NUM> discloses a beam scanner in which four permanent magnets are provided on a rotating shaft to which the mirror is attached so as to be magnetized in the radial direction of the rotating shaft, and a core including magnetic poles around which the coil is wound is disposed so as to sandwich the rotating shaft. <CIT> discloses a rotary reciprocating drive actuator equipped with a movable body having a shaft part and a movable magnet secured to the shaft part. The movable magnet is formed in a ring shape and secured to the shaft part. The drive actuator is configured to reciprocally and rotationally drive the movable body about the shaft part. <CIT> discloses a small-sized vibration type actuator which eliminates the need for a leaf spring.

By the way, in the rotary reciprocating drive actuator of the coil movable type, heat generated by the coil during driving may adversely affect such as a surface state of the mirror, a bonding state of the mirror to the rotating shaft and a shape of the mirror including a warp. Further, in the rotary reciprocating drive actuator of the coil movable type, considering a heat generation of the coil at the time of energization, there are problems that an input current to the coil is difficult to increase and a size and an amplitude of the mirror to be a movable body are difficult to increase. Further, there is a problem that an assemblability is poor, because it is necessary to pull out wirings to the coil to a fixed body side with respect to the mirror to be the movable body.

In PTL <NUM>, since the magnets are disposed on the movable body side, the above problem of the coil movable type can be solved. In PTL <NUM>, however, two magnets per one core pole and a total of four magnets are required in order to make the magnet stationary at the neutral position with respect to the core, that is, in order to position a switching portion of the magnetic pole of the magnet at the center of the core.

Thereby, there is a problem that the amplitude of the movable body is reduced, that is, a swing range is reduced, as compared with the case where an equivalent rotary reciprocating drive actuator is configured by using two poles magnet, for example. Further, since at least four magnets are used, a number of parts is large, the structure is complicated and the assembly is difficult.

In addition, in recent years, it is expected that the mirror to be the movable body will become bigger in the rotary reciprocating drive actuator used in the scanner. In the case that the mirror is big, in a structure rotatably supporting the movable body in a cantilever manner using with the rotary reciprocating drive actuator shown in PTL1, it lacks rigidity and it is difficult to ensure a shock resistance and a vibration resistance.

Further, if an electromagnetic conversion efficiency is low in the rotary reciprocating drive actuator, there are problems that an output is reduced, it is difficult to obtain a predetermined rotation angle, and it is difficult to drive at high speed.

Based on these problems, it is desired that a rotary reciprocating drive actuator that has a rigidity, a shock resistance and a vibration resistance, can improve an ease of assembling and can achieve a high amplitude.

The present invention has been made in consideration of the above points, and provides a rotary reciprocating drive actuator which can be easily assembled and can drive a movable object at a high amplitude by increasing an electromagnetic conversion efficiency to improve an output.

According to one aspect of a rotary reciprocating drive actuator of the present invention, the rotary reciprocating drive actuator comprising:.

According to the present invention, it can be easily assembled and can drive a movable object at a high amplitude by increasing an electromagnetic conversion efficiency to improve an output.

<FIG> is an external perspective view of rotary reciprocating drive actuator <NUM> of the embodiment. <FIG> is an exploded perspective view of rotary reciprocating drive actuator <NUM>.

Rotary reciprocating drive actuator <NUM> is used, for example, in a LIDAR (Laser Imaging Detection and Ranging) apparatus. Note that, rotary reciprocating drive actuator <NUM> is also applicable to an optical scanner device in a multifunction peripheral, a laser beam printer and other apparatus.

Rotary reciprocating drive actuator <NUM> roughly has base part <NUM>; mirror part <NUM> rotatably supported by base part <NUM>; and drive unit <NUM> for driving mirror part <NUM> in a rotary reciprocating manner.

Mirror part <NUM> is a part of a movable object in rotary reciprocating drive actuator <NUM> and constitutes a movable body together with shaft part <NUM>. Mirror part <NUM> is formed by attaching mirror <NUM> to one surface of mirror holder <NUM>, as shown in <FIG> and <FIG>. Mirror holder <NUM> has insertion hole 122a, shaft part <NUM> is inserted into insertion hole 122a, and mirror holder <NUM> and shaft part <NUM> are fixed.

Base part <NUM> is configured of a member which has a pair of wall parts 111a and 111b, and in which cross-section is a substantially U-shape. Insertion hole <NUM> through which shaft part <NUM> is inserted is formed in each of the pair of wall parts 111a and 111b. Further, notched holes <NUM> communicating insertion holes <NUM> and the outer edges of wall parts 111a and 111b are formed in the pair of wall parts 111a and 111b, respectively.

Thus, shaft part <NUM> can be disposed at positions of insertion holes <NUM> through notched holes <NUM> in a state where mirror part <NUM> is fastened to shaft part <NUM>. In the case where notched holes <NUM> are not provided, a complicated assembly operation is required in which shaft part <NUM> is inserted into both insertion holes <NUM> of wall parts 111a, 111b and insertion hole 122a of mirror holder <NUM> while mirror part <NUM> is disposed between the pair of wall parts 111a and 111b, and shaft part <NUM> and mirror holder <NUM> are fastened. In contrast, in the present embodiment, since notched holes <NUM> are formed, shaft part <NUM> to which mirror part <NUM> is fastened in advance can be easily inserted into insertion holes <NUM>.

Ball bearings (bearings) <NUM> are attached to both end portions of shaft part <NUM>. Ball bearings <NUM> are mounted to bearing mounting parts <NUM> formed at the positions of insertion holes <NUM> of the pair of wall parts 111a and 111b. Thus, shaft part <NUM> is rotatably attached to base part <NUM> via ball bearings <NUM>, and mirror part <NUM> is disposed between the pair of wall parts 111a and 111b.

Further, movable magnet <NUM> is fastened to one end of shaft part <NUM>. Movable magnet <NUM> is disposed inside of drive unit <NUM> and is driven in the rotary reciprocating manner by a magnetic flux generated by drive unit <NUM>. Specifically, by a cooperation with coil bodies <NUM>, movable magnet <NUM> rotates shaft part <NUM> of the movable body in one direction and in the other direction around the shaft from the movement reference position in the reciprocating manner with respect to base part <NUM>.

Positioning the movable body including shaft part <NUM> at the movement reference position means that movable magnet <NUM> is positioned at a neutral position with respect to magnetic poles 211a and 212a of core body <NUM> excited by coil bodies <NUM> in the present embodiment. This neutral position is a position capable of rotating similarly in both one direction and the other direction around the shaft (normal rotation and reverse rotation viewed from shaft part <NUM> side).

Movable magnet <NUM> is formed in a ring shape, and has an even number of magnetic poles 161a, 161b in which an S-pole (a South pole) and an N-pole (a North poles) are alternately magnetized in a direction orthogonal to the rotational axis direction of shaft part <NUM> at an outer periphery of shaft part <NUM> (see <FIG>). Although movable magnet <NUM> is magnetized to two poles in the present embodiment, it may be magnetized to two or more poles depending on an amplitude at the time of movement.

The even number of magnetic poles 161a and 161b has magnetization surfaces of different polarities facing opposite direction to each other across shaft part <NUM>. In the present embodiment, magnetic poles 161a and 161b have different polarities in which a plane along the axial direction of shaft part <NUM> is as a boundary thereof.

Further, the even number of magnetic poles 161a and 161b is configured to magnetize at equal intervals at the outer periphery of shaft part <NUM>.

As described above, in movable magnet <NUM>, the even number of magnetic poles 161a and 161b forming the S-pole and the N-pole is alternately disposed at the outer periphery of shaft part <NUM>, and the magnetic poles 161a and 161b are disposed at equal intervals.

More specifically, in movable magnet <NUM>, each of semicircular portions constitutes different magnetic poles 161a and 161b. Arc shaped curved surfaces of the semicircular portions are magnetization surfaces of different magnetic poles 161a and 161b, and the magnetization surfaces of different magnetic poles 161a and 161b are configured to extend in a circumferential direction around an axis.

In other words, the magnetization surfaces of magnetic poles 161a and 161b are disposed in a direction orthogonal to the axial direction of shaft part <NUM>, and are rotated to be able to face to magnetic pole 211a of first core body <NUM> and magnetic pole 212a of second core body <NUM>, respectively.

The number of magnetic poles of movable magnet <NUM> is equal to the number of magnetic poles of core body <NUM>.

Magnetic pole switching portions 161c of magnetic poles 161a and 161b of movable magnet <NUM> are located at positions facing center positions in a width direction of magnetic pole 211a of first core body <NUM> and magnetic pole 212a of second core body <NUM> when coil bodies <NUM> are not energized. Movable magnet <NUM> has two poles of magnetic poles 161a and 161b in the present embodiment. When movable magnet <NUM> is held at a rotational angle position by magnet position holding part <NUM> described later, magnetic pole switching portions 161c are located at positions that are symmetrical in a line centered on shaft part <NUM> with respect to each of magnetic pole 211a and magnetic pole 212a. Thus, by disposing end portions of magnetic pole switching portions 161c toward magnetic poles 211a and 212a to dispose the movable object to correspond to a direction thereof, a rotational direction of shaft part <NUM> is determined for an excitation to coil <NUM>, and a torque of shaft part <NUM> can also be maximized.

Shaft part <NUM> to which mirror part <NUM> to be the movable object is attached is pivotally supported by the pair of wall parts 111a and 111b of base part <NUM> so as to support mirror part <NUM> from both sides. Thus, mirror part <NUM> is supported more firmly than the case where shaft part <NUM> is pivotally supported in a cantilever manner, and a shock resistance and a vibration resistance are improved.

Drive unit <NUM> has core body <NUM> and coil bodies <NUM>, as shown in <FIG> and <FIG>. <FIG> is a perspective view showing a configuration of the drive unit. Drive unit <NUM> is formed in a shape of a rectangular plate in the present embodiment.

Coil body <NUM> has bobbin <NUM> attached to core body <NUM>, and coil <NUM> wound around bobbin <NUM>, as shown in <FIG>. By winding coil <NUM> around bobbin <NUM>, a rectangular cylindrical coil body <NUM> is formed and is disposed to surround a part of core body <NUM>. Coil body <NUM> has first coil <NUM> and second coil <NUM> configured by winding coil <NUM> around bobbin <NUM> in the present embodiment.

In core body <NUM>, one end portion and the other end portion to be magnetic poles 211a and 212a excited by coil bodies <NUM> are disposed so as to sandwich movable magnet <NUM> and face each other. In core body <NUM>, a portion continuous between the one end portion and the other end portion to be magnetic poles 211a and 212a is configured to surround magnetic pole 211a as the one end portion and magnetic pole 212a as the other end portion. Core body <NUM> is formed to surround magnetic poles 211a and 212a as an even number of core magnetic poles, and has a shape continuous between magnetic poles 211a and 212a.

Core body <NUM> includes first core body <NUM>, second core body <NUM> and connecting core <NUM>. Coil body <NUM> is mounted such that each of first core body <NUM> and second core body <NUM> of core body <NUM> is inserted into thereof in the present embodiment. First core body <NUM> and second core body <NUM> are integrally connected by connecting core <NUM>. When the coils of coil bodies <NUM> are energized, core body <NUM> is excited.

Core body <NUM> and coil bodies <NUM> are fixed to wall part 111a of base part <NUM> via fastening members <NUM>.

In core body <NUM>, each of first core body <NUM>, second core body <NUM>, and connecting core <NUM> is a stacked core, and configured by stacked silicon steel plates, for example.

First core body <NUM> and second core body <NUM> include magnetic poles 211a and 212a, and rod-shaped core portions 211b and 212b. Magnetic poles 211a and 212a are formed to sandwich movable magnet <NUM>. Core portions 211b and 212b are disposed to be parallel each other, and magnetic poles 211a and 212a are one end portions of core portions 211b and 212b, respectively.

Other end portions 211c and 212c of core portions 211b and 212b are connected to connecting core <NUM>. First core body <NUM> and second core body <NUM> are formed together with connecting core <NUM> as an integral structure.

Magnetic poles 211a and 212a are disposed to face each other such that movable magnet <NUM> is sandwiched therebetween in a direction orthogonal to a shaft of movable magnet <NUM>. Magnetic poles 211a and 212a have curved surfaces that are curved in a direction along the rotational direction of movable magnet <NUM>.

Core portions 211b and 212b of first core body <NUM> and second core body <NUM> are disposed to extend from respective magnetic poles 211a and 212a in a direction orthogonal to both a direction where magnetic poles 211a and 212a are faced and a direction where shaft part <NUM> is extended.

Coil body <NUM> is disposed around outside of core portions 211b and 212b, respectively. Specifically, first coil <NUM> and second coil <NUM> are respectively disposed around outside of core portions 211b and 212b. Winding directions of coil wires of these first coil <NUM> and second coil <NUM> are set so that the magnetic flux flows suitably from one of magnetic poles 211a and 212a to the other when a current is supplied to coil wires.

The other end portion of first core body <NUM> is connected to one end portion of first side portion <NUM> in connecting core <NUM> disposed to be parallel to first core body <NUM>.

The other end portion of second core body <NUM> is connected to one end portion of second side portion <NUM> in connecting core <NUM> disposed to be parallel to second core body <NUM>.

Connecting core <NUM> is formed to surround movable magnet <NUM> and magnetic poles 211a, 212a.

Connecting core <NUM> is formed in a U-shape in which first core body <NUM> and second core body <NUM> are disposed inside thereof in the present embodiment. Connecting core <NUM> connects between magnetic poles 211a and 212a.

Specifically, connecting core <NUM> is disposed to surround first coil <NUM> and second coil <NUM> from three sides orthogonal to shaft part <NUM> in addition to magnetic pole 211a of first core body <NUM> and magnetic pole 212a of second core body <NUM> which face each other. Connecting core <NUM> covers magnetic pole 211a, magnetic pole 212a, first coil <NUM>, and second coil <NUM> from the remaining one side orthogonal to shaft part <NUM>, together with other end portions 211c and 212c of first core body <NUM> and second core body <NUM>.

Connecting core <NUM> has first side portion <NUM>, second side portion <NUM>, and third side portion <NUM> which connects between first side portion <NUM> and second side portion <NUM>. Connecting core <NUM> integrally includes first side portion <NUM>, second side portion <NUM>, and third side portion <NUM>. Connecting core <NUM> is formed by stacking magnetic materials as well as first core body <NUM> and second core body <NUM>. Connecting core <NUM> is a stacked body in which a thickness thereof is thicker than that of first core body <NUM> and second core body <NUM>. Connecting core <NUM> corresponds to a core outer periphery portion which is a portion surrounding around magnetic poles 211a and 212a in core body <NUM>.

Third side portion <NUM> links the other end portion of first side portion <NUM> and the other end portion of second side portion <NUM> to connect both at the shortest distance. Although connecting core <NUM> has protruding portions, for fixing, protruding in a direction extending third side portion <NUM> from corner portions where first side portion <NUM> and second side portion <NUM> are jointed to both end portions of third side portion <NUM>, connecting core <NUM> is formed in the U-shape as a whole.

Third side portion <NUM> is a rectangular-shaped body. Third side portion <NUM> is disposed to extend in a direction where first core body <NUM> and second core body <NUM> are faced, that is, in the direction where magnetic poles 211a and 212a are faced and orthogonal to the shaft of movable magnet <NUM>.

As shown in <FIG>, drive unit <NUM> has magnet position holding part <NUM> in the present embodiment.

Thus, drive unit <NUM> is configured of first core body <NUM> and second core body <NUM> to which first coil <NUM> and second coil <NUM> are assembled respectively, and U-shaped connecting core <NUM> including first side portion <NUM>, second side portion <NUM>, and third side portion <NUM>. Specifically, core body <NUM> has first core body <NUM> and second core body <NUM> each having a rod-shape and including magnetic poles 211a and 212a at respective tip portions, are inserted into coil bodies <NUM> respectively. Core body <NUM> has connecting core <NUM> connecting between first core body <NUM> and second core body <NUM>. First core body <NUM> and second core body <NUM> are disposed in parallel so that magnetic poles 211a and 212a are faced. Connecting core <NUM> is formed in the U-shape to surround first core body <NUM> and second core body <NUM>. Connecting core <NUM> is disposed to surround first core body <NUM> and second core body <NUM> and both end portions thereof are jointed to each of base end portions of first core body <NUM> and second core body <NUM>. Thus, it is possible to minimize the number of components in the core, reduce cost, and improve ease of assembly.

Magnet position holding part <NUM> is made of a magnet. Magnet position holding part <NUM> functions as a magnetic spring together with movable magnet <NUM> by the magnetic attraction force generated between it and movable magnet <NUM>. The magnetic spring rotatably holds the movable body including movable magnet <NUM>, shaft part <NUM> and other portions so that the movable body is positioned at the movement reference position in a normal state. Here, the normal state is a state where coil bodies <NUM> are not energized. Magnet position holding part <NUM> magnetically attracts movable magnet <NUM> by the magnetic spring so that rotatable movable magnet <NUM> is positioned at the movement reference position.

The movement reference position at which magnet position holding part <NUM> magnetically attracts movable magnet <NUM> is a rotational center position of rotary reciprocation of movable magnet <NUM>. When the movable body is positioned at the movement reference position, magnetic pole switching portions 161c of movable magnet <NUM> are positioned at positions facing the magnetic poles of coil bodies <NUM> side.

Magnet position holding part <NUM> is attached to third side portion <NUM> so as to project to movable magnet <NUM> side, and disposed to face movable magnet <NUM> with air gap G therebetween.

Magnet position holding part <NUM> is, for example, a magnet whose facing surface is magnetized to the N-pole (see <FIG>). Magnet position holding part <NUM> may be formed integrally with third side portion <NUM>. Magnet position holding part <NUM> positions movable magnet <NUM> at the movement reference position and holds it at this position.

Magnet position holding part <NUM> is a magnet magnetized toward movable magnet <NUM>. Magnet position holding part <NUM> locates magnetic pole switching portions 161c of movable magnet <NUM> at positions facing magnetic poles 211a and 212a when movable magnet <NUM> is positioned at the movement reference position (the neutral position). In other words, magnetic pole switching portions 161c, which are positions of switching of the magnetic poles of the even number of magnetic poles 161a and 161b, position on the same radius of an axis centered on shaft part <NUM> with respect to centers of lengths in a circumferential direction around an axis of magnetic poles 211a and 212a. Thus, the even number of magnetic poles 161a and 161b becomes a state to be a position capable of rotating similarly in both one direction and the other direction around the shaft with respect to magnetic poles 211a and 212a.

As described above, magnet position holding part <NUM> and movable magnet <NUM> are attracted to each other, and magnet position holding part <NUM> can position movable magnet <NUM> at the movement reference position. Thus, magnetic pole switching portions 161c of movable magnet <NUM> face magnetic pole 211a of first core body <NUM> and magnetic pole 212a of second core body <NUM>. At this position, drive unit <NUM> generates the maximum torque to stably drive the movable body. Since movable magnet <NUM> is magnetized with two poles, the movable object can be easily driven at a high amplitude and vibration performance can be improved by cooperation with core body <NUM>.

Further, as shown in <FIG>, drive unit <NUM> has spacer parts <NUM> in the present embodiment. Spacer parts <NUM> fix magnetic poles 211a and 212a to first side portion <NUM> and second side portion <NUM> close to each of magnetic poles 211a and 212a. Further, spacer parts <NUM> has a function to suitably flow the magnetic flux between magnetic poles 211a and 212a in core body <NUM> through core body <NUM> between magnetic poles 211a and 212a.

Spacer parts <NUM> are respectively sandwiched between first core body <NUM> and first side portion <NUM> and between second core body <NUM> and second side portion <NUM> which are disposed side by side next to each other, and are provided to be fixed thereto. Spacer parts <NUM> can increase a rigidity of core body <NUM> itself by fixing first side portion <NUM> and second side portion <NUM> to magnetic poles 211a and 212a via spacer parts <NUM>. Thus, deformation or breakage of magnetic poles 211a and 212a due to magnetic attraction with movable magnet <NUM> or impact can be suppressed.

Spacer parts <NUM> fix magnetic pole 211a, which is a free end in first core body <NUM>, to first side portion <NUM> of connecting core <NUM>, and fix magnetic pole 212a, which is a free end in second core body <NUM>, to second side portion <NUM> of connecting core <NUM>.

Further, spacer parts <NUM> regulate flowing the magnetic flux in a direction where first core body <NUM> and first side portion <NUM> are faced, that is, in a direction different from a magnetic path by core body <NUM>. Further, spacer parts <NUM> regulate flowing the magnetic flux in a direction where second core body <NUM> and second side portion <NUM> are faced, that is, in a direction different from a direction where second core body <NUM> and second side portion <NUM> are continuous with each other (a direction where the magnetic flux flows) as the magnetic path by core body <NUM>.

Spacer parts <NUM> are preferable to be a non-magnetic material that is not attracted to a magnet, and preferable to be made of brass or aluminum, for example.

For example, spacer part <NUM> is disposed to be sandwiched between first core body <NUM> and first side portion <NUM> which are disposed side by side next to each other, and fix to both first core body <NUM> and first side portion <NUM> by adhesion, welding and others. Thus, spacer parts <NUM> can be fixed to core body <NUM> more firmly by making a material thereof a non-magnetic and weldable member such as brass or aluminum.

Spacer parts <NUM> may be components that are fixed by adhesion to at least one of first core body <NUM> and first side portion <NUM> or at least one of second core body <NUM> and second side portion <NUM> which are adjacent to each other. For example, spacer parts <NUM> may be integrally provided with first coil <NUM> and second coil <NUM> which constitute coil bodies <NUM> in drive unit <NUM>. For example, spacer part <NUM> may be fixed by being simply disposed to be sandwiched between first core body <NUM> and first side portion <NUM> which are disposed side by side next to each other.

In drive unit 200A shown in <FIG>, each of spacer parts 230A is integrally provided with each of bobbins <NUM> that comprise first coil 221A and second coil 222A.

Spacer parts 230A are provided so as to be positions where spacer parts 230A overlap back sides of magnetic poles 211a and 212a when first coil 221A and second coil 222A are respectively assembled to first core body <NUM> and second core body <NUM>. For example, spacer parts 230A are integrally formed with bobbins 225a, as bobbin body 225A using resin and others. Note that, compared with drive unit <NUM>, drive unit 200A differs only in configurations of spacer parts 230A, first coil 221A, and second coil 222A, but the other configurations are the same. Therefore, only different components compared with drive unit <NUM> will be described, and similar components will be omitted.

As described above, spacer parts 230A are respectively disposed between first core body 211A and first side portion <NUM> and between second core body 212A and second side portion <NUM> by simply assembling first coil 221A and second coil 222A as coil bodies 220A to core body <NUM>. Thus, a number of parts can be reduced as well as a fixing strength of magnetic poles 211a and 212a can be increased by integrating spacer parts 230A and bobbin <NUM>.

Next, an operation of rotary reciprocating drive actuator <NUM> will be described with reference to <FIG> and <FIG> in addition to <FIG>. <FIG> and <FIG> are views for explaining an operation of a magnetic circuit of rotary reciprocating drive actuator <NUM>.

Two magnetic poles 211a and 212b are disposed to face each other so as to sandwich movable magnet <NUM> with air gap G between them and the outer periphery of movable magnet <NUM>.

As shown in <FIG>, when coil bodies <NUM> (<NUM>, <NUM>) are not energized, movable magnet <NUM> is positioned at the movement reference position by the magnetic attraction force between magnet position holding part <NUM> and movable magnet <NUM>, that is, the magnetic spring.

In this movement reference position (the movement reference position may be referred to as a normal state in the present invention), one of magnetic poles 161a and 161b of movable magnet <NUM> is attracted to magnet position holding part <NUM>, and magnetic pole switching portions 161c are positioned at positions facing the center positions of magnetic pole 211a of first core body <NUM> and magnetic pole 212a of second core body <NUM>.

When coil bodies <NUM> are energized, coil bodies <NUM> (<NUM>, <NUM>) excite first core body <NUM> and second core body <NUM>.

When coil bodies <NUM> are energized in the direction shown in <FIG>, magnetic pole 211a is magnetized to the N-pole, and magnetic pole 212a is magnetized to the S-pole.

As a result, in first core body <NUM>, the magnetic flux is formed in which the magnetic flux is emitted from magnetic pole 211a magnetized to the N-pole to movable magnet <NUM>, flows through movable magnet <NUM>, magnet position holding part <NUM>, and connecting core <NUM> (third side portion <NUM>) in this order, and enters into core portion 211b.

In second core body <NUM>, the magnetic flux is emitted from core portion 212b to connecting core <NUM> (second side portion <NUM>) side, flows through connecting core <NUM>, magnet position holding part <NUM>, and movable magnet <NUM> in this order, and enters magnetic pole 212a.

Thus, magnetic pole 211a magnetized to the N-pole is attracted to the S-pole in movable magnet <NUM>, magnetic pole 212a magnetized to the S-pole is attracted to N-pole in movable magnet <NUM>, a torque in the F direction is generated around the axis of shaft part <NUM> in movable magnet <NUM>, and movable magnet <NUM> rotates in the F direction. Accordingly, shaft part <NUM> also rotates, and mirror part <NUM> fixed to shaft part <NUM> also rotates.

Next, as shown in <FIG>, when the energization direction of coil bodies <NUM> are switched to the opposite direction, magnetic pole 211a is magnetized to the S-pole, magnetic pole 212a is magnetized to the N-pole, and the flow of the magnetic flux is also reversed.

Thus, magnetic pole 211a magnetized to the S-pole is attracted to the N-pole in movable magnet <NUM>, magnetic pole 212a magnetized to the N-pole is attracted to the S-pole in movable magnet <NUM>, a torque in the direction opposite to the F direction is generated around the axis of shaft part <NUM> in movable magnet <NUM>, and movable magnet <NUM> rotates in the direction opposite to the F direction. Accordingly, shaft part <NUM> also rotates in the opposite direction, and mirror part <NUM> fixed to shaft part <NUM> also rotates in the opposite direction. By repeating these motions, rotary reciprocating drive actuator <NUM> drives mirror part <NUM> in the rotary reciprocating manner.

In practice, rotary reciprocating drive actuator <NUM> is driven by an alternating current wave input from a power supply unit (for example, corresponding to drive signal supply unit <NUM> in <FIG>) to coil bodies <NUM>. That is, the energization directions of coil bodies <NUM> are periodically switched, and the torque in the F direction around the axis and the torque in the direction opposite to the F direction (- F direction) alternately act on the movable body. Thus, the movable body is driven in the rotary reciprocating manner.

Incidentally, at the time of switching the energization direction, the magnetic attraction force between magnet position holding part <NUM> and movable magnet <NUM> is generated, that is, magnetic spring torque FM (<FIG>) or - FM (<FIG>) is generated by the magnetic spring, and movable magnet <NUM> is urged to the movement reference position.

The driving principle of rotary reciprocating drive actuator <NUM> will be briefly described below. In rotary reciprocating drive actuator <NUM> of the present embodiment, when the moment of inertia of the movable body is J [kg·m<NUM>] and the spring constant in the torsional direction of the magnetic spring (magnetic poles 211a and 212a, magnet position holding part <NUM>, and movable magnet <NUM>) is Ksp, the movable body vibrates (rotary reciprocates) with respect to base part <NUM> at a resonance frequency Fr [Hz] calculated by the equation (<NUM>).

Since the movable body constitutes a mass portion in a vibration model of a spring - mass system, when an alternating current wave having a frequency equal to the resonance frequency Fr of the movable body is inputted to coil bodies <NUM>, the movable body enters a resonance state. That is, by inputting the alternating current wave having a frequency substantially equal to the resonance frequency Fr of the movable body to coil bodies <NUM> from the power supply unit, the movable body can be efficiently vibrated.

A motion equation and a circuit equation showing the driving principle of rotary reciprocating drive actuator <NUM> are shown below. Rotary reciprocating drive actuator <NUM> is driven based on the motion equation expressed by the equation (<NUM>) and the circuit equation expressed by the equation (<NUM>).

That is, the moment of inertia J [kg·m<NUM>], the rotation angle θ(t) [rad], the torque constant K<NUM> [N·m/A], the current I(t) [A], the spring constant Ksp [N·m/rad], the damping coefficient D [N·m/(rad/s)], the load torque TLoss [N·m], and the like of the movable body in rotary reciprocating drive actuator <NUM> can be appropriately changed within the range satisfying the equation (<NUM>). Further, the voltage e(t) [V], the resistance R [Ω], the inductance L [H], and the counter electromotive force constant Ke [V/(rad/s)] can be appropriately changed within the range satisfying the equation (<NUM>).

Thus, rotary reciprocating drive actuator <NUM> can obtain an efficient and large vibration output when the coil is energized by the alternating current wave corresponding to the resonance frequency Fr determined by the moment of inertia J of the movable body and the spring constant Ksp of the magnetic spring.

According to rotary reciprocating drive actuator <NUM> of the present embodiment, since a torque generation efficiency is high, heat is hard to transfer to mirror <NUM> which is the movable object, and as a result, a flatness of a reflection surface of mirror <NUM> can be ensured with high accuracy. Further, a manufacturing efficiency is high, an assembly accuracy is good, and even if the movable object is a large sized mirror, it can be driven at a high amplitude.

Further, according to rotary reciprocating drive actuator <NUM>, mirror part <NUM> disposed between the pair of wall parts 111a and 111b of base part <NUM> via shaft part <NUM> is supported to be able to move in the rotary reciprocating manner by drive unit <NUM> at one side of shaft part <NUM>.

Thus, rotary reciprocating drive actuator <NUM> itself can be reduced in size according to a size of mirror part <NUM> to be the movable object, and an arrangement space thereof can be used efficiently even in a small arrangement space. Further, since drive unit <NUM> is disposed only one side of the pair of wall parts 111a and 111b which sandwich mirror part <NUM>, wiring of coil <NUM> and others can be simplified.

<FIG> are views for explaining rotary reciprocating drive actuator 100A according to Modification <NUM> of the rotary reciprocating drive actuator. <FIG> is an external perspective view of rotary reciprocating drive actuator 100A according to Modification <NUM>, <FIG> is a longitudinal sectional view showing a configuration of a main part of rotary reciprocating drive actuator 100A. <FIG> is an exploded perspective view showing angle sensor part <NUM> of rotary reciprocating drive actuator 100A.

Rotary reciprocating drive actuator 100A is provided with angle sensor part <NUM> to the configuration of rotary reciprocating drive actuator.

Angle sensor part <NUM> is for detecting a rotation angle of shaft part <NUM>, and attached to wall part 111b side, to which drive unit <NUM> is not attached, in the pair of wall parts 111a and 111b of base part <NUM>.

Note that a configuration of rotary reciprocating drive actuator 100A is the same as the configuration of rotary reciprocating drive actuator <NUM> except including angle sensor part <NUM>. Therefore, angle sensor part <NUM> is mainly explained in the following description of rotary reciprocating drive actuator 100A, and the other components, that is, components similar to the components of rotary reciprocating drive actuator <NUM>, are omitted.

Angle sensor part <NUM> has circuit board <NUM>; optical sensor <NUM> and connector <NUM> mounted on circuit board <NUM>; encoder disk <NUM>; and case <NUM>. Circuit board <NUM> is fixed to case <NUM> by fastening members <NUM>. Case <NUM> is fixed to wall part 111b by fastening members <NUM>.

Encoder disk <NUM> is mounted by fastening to shaft part <NUM> via mounting member <NUM>, and rotates integrally with movable magnet <NUM> and mirror part <NUM>. That is, mounting member <NUM> has an insertion hole through which shaft part <NUM> is inserted and fastened, and a flange portion to which encoder disk <NUM> is abutted and fastened, and mounting member <NUM> is fixed to both shaft part <NUM> and encoder disk <NUM>. As a result, a rotational position of encoder disk <NUM> is the same as a rotational position of shaft part <NUM>. Optical sensor <NUM> emits light to encoder disk <NUM> and detects the rotational position (angle) of encoder disk <NUM> based on the reflected light. Thereby, the rotational position of movable magnet <NUM> and mirror part <NUM> can be detected by optical sensor <NUM>. Thus, it is possible to detect the rotational position of the movable object including movable magnet <NUM> and shaft part <NUM>, and it is possible to control an angular position and a speed of movable body, specifically mirror part <NUM> to be the movable object, during driving.

In rotary reciprocating drive actuator 100A, movable magnet <NUM> in the movable body and drive unit <NUM> including coil bodies <NUM>, core body <NUM>, and others are attached to an outer surface side of one wall part 111a of the pair of wall parts 111a and 111b of base part <NUM>. On the other hand, angle sensor part <NUM> for detecting the rotation angle of shaft part <NUM> is attached to an outer surface side of the other wall part 111b of the pair of wall parts 111a and 111b of base part <NUM>. This makes it easy to remove angle sensor part <NUM> and adjust an assembly position thereof. Since angle sensor part <NUM> can be easily removed, angle sensor part <NUM> can be easily replaced when a failure occurs in angle sensor part <NUM>.

Further, angle sensor part <NUM> can be assembled at the final stage of assembly. As a result, the expensive angle sensor part <NUM> can be assembled after it is confirmed that the assembly of the other components is normal. Therefore, a risk of wasting the expensive angle sensor part <NUM> due to the assembly failure of the other components can be suppressed. Note that, rotary reciprocating drive actuators <NUM> and 100A of the present embodiment are used in scanners capable of optical scanning, and can be driven by resonance, but can also be driven by non-resonance.

<FIG> is a block diagram showing a configuration of a main part of scanner system using rotary reciprocating drive actuator 100A of Modification <NUM>.

Scanner system <NUM>, as an example of the optical scanner device, has laser emitting unit <NUM>; laser control unit <NUM>; drive signal supply unit <NUM>; and position control signal calculation unit <NUM> in addition to rotary reciprocating drive actuator 100A.

Laser emitting unit <NUM> includes, for example, an LD (laser diode) to be a light source; a lens system for converging a laser beam output from the light source, and others. Laser control unit <NUM> controls laser emitting unit <NUM>. The laser beam obtained by laser emitting unit <NUM> is incident on mirror <NUM> of rotary reciprocating drive actuator 100A.

Position control signal calculation unit <NUM> generates and outputs a drive signal for controlling shaft part <NUM> (mirror <NUM>) to be the target angular position with reference to the angular position of shaft part <NUM> (mirror <NUM>) acquired by angle sensor part <NUM> and the target angular position. For example, position control signal calculation unit <NUM> generates a position control signal on the basis of the obtained angular position of shaft part <NUM> (mirror <NUM>) and a signal indicating the target angular position converted using sawtooth waveform data, and the like stored in a waveform memory which is not illustrated, and outputs the position control signal to drive signal supply unit <NUM>.

Based on the position control signal, drive signal supply unit <NUM> supplies the drive signal to coil bodies <NUM> of rotary reciprocating drive actuator <NUM> such that the angular position of shaft part <NUM> (mirror <NUM>) becomes a desired angular position. Thus, scanner system <NUM> can emit a scanning light from rotary reciprocating drive actuator 100A to a predetermined scanning area.

<FIG> is a perspective view showing rotary reciprocating drive actuator according to Modification <NUM> of the present embodiment.

Rotary reciprocating drive actuator 100B of Modification <NUM> is provided with another drive unit 200B configured in the same way as drive unit <NUM> in addition to the configuration of rotary reciprocating drive actuator <NUM>.

In other words, rotary reciprocating drive actuator 100B has
base part <NUM>; mirror part <NUM> rotatably supported by base part <NUM> via shaft part <NUM>; and drive units <NUM> and 200B, disposed both end portion sides of shaft part <NUM>, for driving mirror part <NUM> in the rotary reciprocating manner.

Movable magnet <NUM> is attached to the other end portion of shaft part <NUM> in the same way as the one end portion thereof, and drive unit 200B is provided corresponding to movable magnet <NUM> in the same way as drive unit <NUM> at the one end portion of shaft part <NUM>. Note that, drive unit 200B drives in the same rotary reciprocating manner as the rotary reciprocating manner to movable magnet <NUM> by drive unit <NUM> to which the current is supplied.

In rotary reciprocating drive actuator 100B, mirror part <NUM> as the movable object is disposed between the pair of wall parts 111a and 111b via ball bearings <NUM>. It can be said that mirror part <NUM> is disposed at a position sandwiched by ball bearings <NUM>, and mirror part <NUM> is held by the pair of wall parts 111a and 111b via ball bearings <NUM>.

Thus, since mirror part <NUM> to be the movable object is sandwiched by ball bearings <NUM>, it is possible to hold mirror part <NUM> stably even when mirror part <NUM> is enlarged, provide excellent impact resistance and vibration resistance, and improve a reliability of driving.

In addition, since mirror part <NUM> is supported to be able to move in the rotary reciprocating manner by drive units <NUM> and 200B respectively disposed both sides of shaft part <NUM> which supports mirror part <NUM>, it is possible to generate larger driving force than that by a configuration whose drive units <NUM> and 200B are provided at one side.

As described above, rotary reciprocating drive actuator <NUM> of the present embodiment includes base part <NUM>; movable magnet <NUM> fixed to shaft part <NUM> to which the movable object (mirror part <NUM> in the example of the embodiment) is connected; and drive unit <NUM> including core body <NUM> and coil bodies <NUM> for generating the magnetic flux in core body <NUM> when the current is supplied, and driving movable magnet <NUM> in a rotary reciprocating manner by the electromagnetic interaction between the magnetic flux generated from core body <NUM> and movable magnet <NUM>.

Further, in rotary reciprocating drive actuator <NUM>, movable magnet <NUM> is formed in the ring shape, and is configured by alternately magnetizing the even number of magnetic poles forming the S-pole and the N-pole at the outer periphery of shaft part <NUM>. The number of magnetic poles of core body <NUM> and the number of magnetic poles of movable magnet <NUM> are equal to each other; the even number of magnetic poles of core body <NUM> is respectively arranged to face movable magnet <NUM> with the air gap therebetween on the outer peripheral side of shaft part <NUM>. Drive unit <NUM> is provided with magnet position holding part <NUM> which is a magnetic material provided to face movable magnet <NUM> and magnetically attracts movable magnet <NUM> to a reference position.

Thus, since movable magnet <NUM> is magnetically attracted to the neutral position (movement reference position) by magnet position holding part <NUM> every time the energization direction is switched, good energy efficiency, good responsiveness, and high amplitude rotary reciprocating drive are realized. Further, compared with the rotary reciprocating drive actuator of the coil movable type, the heat generated by coil bodies <NUM> is hard to transfer to the movable object, and when the movable object is a mirror, it is possible to prevent adverse effects (bond deterioration, warpage, etc.) of the heat from affecting the mirror.

In core body <NUM> of drive unit <NUM>, magnetic poles 211a and 212a are disposed to face each other with sandwiching movable magnet <NUM>. First coil <NUM> and second coil <NUM> are disposed around outside of core body <NUM> with adjacent to each of magnetic poles 211a and 212a. Further, other end portions 211c and 212c of first core body <NUM> and second core body <NUM> to which first coil <NUM> and second coil <NUM> are attached are connected to connecting core <NUM>. Connecting core <NUM> is disposed to surround first coil <NUM>, second coil <NUM>, magnetic poles 211a, 212a, and movable magnet <NUM> in the direction orthogonal to shaft part <NUM>. Core body <NUM> is formed to surround magnetic poles 211a and 212a as an even number of core magnetic poles, and has a shape continuous between magnetic poles 211a and 212a.

In core body <NUM>, for example, magnetic poles 211a and 212a sandwich movable magnet <NUM> in the direction orthogonal to shaft part <NUM>. Further, first coil <NUM> and second coil <NUM> are disposed adjacent to magnetic poles 211a and 212a, and extended in the direction orthogonal to shaft part <NUM> and the direction where magnetic poles 211a and 212a are faced. Magnetic poles 211a, 212a, first coil <NUM> and second coil <NUM> are surrounded by first side portion <NUM>, second side portion <NUM>, third side portion <NUM>, portions to where other end portions 211c, 212c are connected in connecting core <NUM>, and other end portions 211c, 212c in the direction orthogonal to shaft part <NUM>.

In core body <NUM>, coil bodies <NUM> (first coil <NUM> and second coil <NUM>) are disposed adjacent or close to magnetic poles 211a and 212a, and the magnetic circuit communicating magnetic poles 211a and 212a is formed at the shortest distance to surround them.

Thus, it is possible to improve the electromagnetic conversion efficiency in the magnetic circuit and improve the output.

In addition, in rotary reciprocating drive actuator <NUM> of the present embodiment, the pair of wall parts 111a and 111b for rotatably supporting shaft part <NUM> via bearings <NUM> are provided to stand in base part <NUM>. The movable object (mirror part <NUM> in the example of the embodiment) is disposed between the pair of wall parts 111a and 111b.

Thus, the movable object (mirror part <NUM>) is disposed so as to be sandwiched by ball bearings <NUM> at both sides of the movable object, it is possible to hold the movable object stably, and improve a reliability of with regard to a durability as rotary reciprocating drive actuator <NUM>.

Further, angle sensor part <NUM> for detecting the rotation angle of shaft part <NUM> is attached to the outer surface side of the other wall part 111b of the pair of wall parts 111a and 111b. This makes it easy to remove angle sensor part <NUM> and adjust the assembly position thereof. Since angle sensor part <NUM> can be easily removed, angle sensor part <NUM> can be easily replaced when the failure occurs in angle sensor part <NUM>. Further, angle sensor part <NUM> can be assembled at the final stage of assembly. As a result, the expensive angle sensor part <NUM> can be assembled after it is confirmed that the assembly of the other components is normal. Therefore, the risk of wasting the expensive angle sensor part <NUM> due to the assembly failure of the other components can be suppressed.

In one aspect of the present invention, the movement reference position where magnet position holding part <NUM> magnetically attracts movable magnet <NUM> and positions movable magnet <NUM> of the normal state is the rotational center position of rotary reciprocation around shaft part <NUM> of movable magnet <NUM>.

In one aspect of the present invention, in movable magnet <NUM>, the even number of magnetic poles is magnetized at equal intervals at the outer periphery of shaft part <NUM>. In one aspect of the present invention, magnet position holding part <NUM> is disposed at the position between the even number of magnetic poles of core body <NUM> and at the position facing movable magnet <NUM> in the radial direction of movable magnet <NUM>. Due to these configuration, movable magnet <NUM>, that is, the movable object including shaft part <NUM> rotates same angular range from the neutral position to one direction and the other direction in the reciprocating manner, thereby maximizing the drive torque and stabilizing the direction of the drive torque.

The above embodiments are merely specific examples for carrying out the present invention, and the technical scope of the present invention should not be construed to be limited by them. That is, the present invention can be implemented in a variety of ways without departing from the spirit or essential features thereof.

In the above embodiment, the case where wall part 111b to attach angle sensor part <NUM> is formed integrally with base part <NUM> is described. A wall part to attach angle sensor part <NUM>, however, may not be formed integrally with base part <NUM> but may be attached to the base part later.

In the above embodiments, the case where drive units <NUM>, 200A, and 200B are mounted on the outer surface side of wall parts 111a and 111b is described. The positions of drive units <NUM>, 200A, and 200B, however, are not limited thereto. Drive units <NUM>, 200A, and 200B may be mounted, for example, on the inner surface side of wall part 111a.

In the above embodiments, the case where the movable object driven by rotary reciprocating drive actuator <NUM>, that is, the movable object attached to shaft part <NUM> is mirror part <NUM> is described. The movable object, however, is not limited thereto. For example, a camera or the like may be the movable object.

Claim 1:
A rotary reciprocating drive actuator, comprising:
a base part (<NUM>);
a movable magnet (<NUM>) fixed to a shaft part (<NUM>) to which a movable object is connected; and
a drive unit (<NUM>) including a core body (<NUM>) and a coil body (<NUM>) disposed around outside of a part of the core body (<NUM>), the drive unit (<NUM>) being configured to generate a magnetic flux in the core body (<NUM>) when a current is supplied, and drive the movable magnet (<NUM>) in a rotary reciprocating manner by an electromagnetic interaction between the magnetic flux generated from the core body (<NUM>) and the movable magnet (<NUM>),
wherein the movable magnet (<NUM>) is formed in a ring shape, and is configured by alternately magnetizing an even number of magnetic poles forming an S-pole and an N-pole at an outer periphery of the shaft part (<NUM>);
a number of core magnetic poles (211a, 212a) as magnetic poles of the core body (<NUM>) and a number of magnetic poles of the movable magnet (<NUM>) are equal to each other;
the core magnetic poles (211a, 212a) are disposed to face the movable magnet (<NUM>) with an air gap therebetween on an outer peripheral side of the movable magnet (<NUM>) in a direction orthogonal to the shaft part (<NUM>);
the drive unit (<NUM>) is provided with a magnet position holding part (<NUM>) which is a magnetic material provided to face the movable magnet (<NUM>) and magnetically attracts the movable magnet (<NUM>) to a reference position of an operation;
the core body (<NUM>) has a shape that connects between one end portion side and another end portion side among an even number of the core magnetic poles (211a, 212a) so as to surround the even number of the core magnetic poles (211a, 212a); and
the coil body (<NUM>) is disposed at the core body (<NUM>) adjacent to each of the even number of the core magnetic poles (211a, 212a),
wherein each core magnetic pole (211a, 212a) is disposed with a gap from a portion that surrounds the core magnetic poles (211a, 212a) in the core body (<NUM>), characterized in that
a spacer part (<NUM>) is disposed at the gap between each core magnetic pole (211a, 212a) and the portion.