Patent Description:
Conventionally, a technique for scanning light from a light source along a straight scanning line has been widely used in laser processing devices, image forming devices, and the like. PTL <NUM> and <NUM> disclose a device provided in this type of apparatus.

The mirror rotation device of PTL <NUM> is provided with a light projection means and a light reflection means. The light projection means is provided with a mirror rotation device having a plurality of planar mirrors arranged in a regular polygonal shape. By reflecting light incident in a predetermined direction by one planar mirror in the mirror rotation device which rotates, the planar mirror rotation device radiates the light while moving angularly at a constant angular velocity. The light reflection means reflects the light emitted from the light projection means by a plurality of reflectors and leads the light to an arbitrary irradiated point on a predetermined scanning line.

The polygon mirror rotation device of PTL <NUM> has a light projection means and a light reflection means. The light projection means has a polygon mirror. Light incident in a predetermined direction is reflected by a reflection surface of each side of a regular polygon included by the polygon mirror which rotates. Accordingly, the polygon mirror radiates the light while moving angularly at a constant angular velocity. The light reflection means reflects the light emitted from the light projection means by a plurality of reflectors and leads the light to an arbitrary irradiated point on a predetermined scanning line.

Regarding the mirror rotation device of PTL <NUM>, the light projection means has only a mirror rotation device. Accordingly, scanning distortion and the like occur due to fluctuations in the reflection position of the light at each planar mirror of the mirror rotation device as the mirror rotation device rotates. Also, regarding the polygon mirror rotation device of PTL <NUM>, the light projection means has only a polygon mirror rotation device. Accordingly, scanning distortion and the like occur due to the fact that the reflection position of the light at each side reflection surface of the regular polygon included by the polygon mirror fluctuates as the polygon mirror rotates.

Therefore, the mirror rotation device of PTL <NUM> is provided with a reciprocating motion mechanism that sequentially reciprocates the planar mirror, and suppresses the fluctuation of the reflection position of the light by reciprocating the planar mirror. In addition, the polygon mirror rotation device of PTL <NUM> is provided with a support member that rotatably supports the polygon mirror and a reciprocating motion mechanism that reciprocates the support member. By reciprocating the polygon mirror together with the support member, the reflection position of the light is suppressed from fluctuating.

Also known as the aforementioned apparatus is an apparatus equipped with a mirror galvanometer having a configuration in which a movable part including a reflective mirror performs reciprocating oscillating motion. In this apparatus, the movable part of the mirror galvanometer is oscillated while adjusting its oscillation speed, thereby preventing the reflection position of light from fluctuating.

Although the mirror rotation device of PTL <NUM> and the polygon mirror rotation device of PTL <NUM> described above can suppress the fluctuation of the reflection position of the light, they cannot prevent it completely. In addition, in the device with the mirror galvanometer, in which the movable part of the mirror galvanometer has to be accelerated and decelerated when oscillates, the scanning area scanned by the device becomes narrower and the processable range of the irradiated object to which the light is irradiated decreases in order to prevent the reflection position of the light from fluctuating.

The present invention has been made in view of the circumstances described above, and an object of the present invention is to prevent the reflection position of light from fluctuating in a device for deflecting light incident in a predetermined direction, without reducing the processable range of an irradiated object to be irradiated by the light.

The problem to be solved by the present invention is as described above, and next, means for solving the problem and effects thereof will be described.

The invention is defined in the independent claim.

Further aspects of the invention are defined in the dependent claims. A special aspect concerns an optical scanning device having the following configuration. That is, the optical scanning device comprises a rotation mirror, a drive unit, and an irradiation device. The drive unit rotates the rotation mirror. The irradiation device irradiates light onto the rotation mirror. The rotation mirror comprises a first regular polygon pyramid and a second regular polygon pyramid. The second regular polygon pyramid is arranged facing the first regular polygon pyramid with an axis coincident with the first regular polygon pyramid. Side surfaces of each of the first regular polygon pyramid and the second regular polygon pyramid are light reflection surfaces each of which is formed in a planar shape. The number of sides of regular polygons is equal in a first base surface that the first regular polygon pyramid has and a second base surface that the second regular polygon pyramid has. The first base surface and the second base surface are both arranged perpendicular to the axis. The first regular polygon pyramid and the second regular polygon pyramid are rotated integrally with each other around the axis as a rotation axis by the drive unit while a phase of the regular polygon of the first base surface and a phase of the regular polygon of the second base surface are matched with each other. A base angle of the first regular polygon pyramid is α° when the first regular polygon pyramid is cut along a plane that includes the axis and a midpoint of one of the sides of the regular polygon of the first base surface. A base angle of the second regular polygon pyramid is (<NUM>-α)° when the second regular polygon pyramid is cut along a plane that includes the axis and a midpoint of one of the sides of the regular polygon of the second base surface. A distance between the first base surface and the second base surface is equal to the sum of a distance between the midpoint of one side of the regular polygon of the first base surface and the rotation axis multiplied by tan α and a distance between the midpoint of one side of the regular polygon of the second base surface and the rotation axis multiplied by tan(<NUM>-α). The irradiation device irradiates the light toward a position so that the light intersects the rotation axis of the rotation mirror.

As a result, the reflection position of the light relative to the incident light is constant in regards to the reflection member, and thus the reflection position of the light is prevented from fluctuating. Therefore, distortion can be prevented when scanning is performed.

According to the present invention, in the light reflection device that deflects light incident in a predetermined direction, it is possible to prevent a reflection position of the light from fluctuating.

Next, an embodiment of the present invention will be described with reference to the drawings. Initially, referring to <FIG>, a configuration of a laser processing device (optical scanning device) <NUM> comprising a light guide device <NUM> according to a first embodiment of the present invention will be described. <FIG> is a diagonal view of the laser processing device <NUM>.

The laser processing device <NUM> shown in <FIG> can process a workpiece <NUM> by irradiating a laser beam onto the workpiece (object to be irradiated) <NUM> while scanning the workpiece <NUM> by light.

In the present embodiment, the laser processing device <NUM> can perform non-thermal processing. For example, the non-thermal processing includes ablation processing. The ablation processing is a processing in which a part of the workpiece <NUM> is vaporized by irradiating a laser beam to the part of the workpiece <NUM>. The laser processing device <NUM> may be configured to perform thermal processing in which the workpiece <NUM> is melted by the heat of the laser beam.

The workpiece <NUM> is a plate-like member. The workpiece <NUM> is made of, for example, CFRP (carbon fiber reinforced plastic). The workpiece <NUM> is not limited to a plate-like member, and may be, for example, a block-like member. Also, the workpiece <NUM> may be made of other materials.

The laser beam used in the laser processing device <NUM> may be visible light or electromagnetic waves in a wavelength band other than visible light. In this embodiment, not only visible light but also various electromagnetic waves with a wider wavelength band than that are included and referred to as "light".

As shown in <FIG>, the laser processing device <NUM> includes a conveyance section <NUM>, a laser generator <NUM>, a light guide device <NUM>.

The conveyance section <NUM> can move the workpiece <NUM> in a direction (sub scanning direction) that is substantially orthogonal to a main scanning direction of the laser processing device <NUM>. Laser processing is performed while the workpiece <NUM> is moved by the conveyance section <NUM>.

In this embodiment, the conveyance section <NUM> is a belt conveyor. The conveyance section <NUM> is not particularly limited. The conveyance section <NUM> may be a roller conveyor, or may be a configuration in which the workpiece <NUM> is grasped and conveyed. Also, the conveyance section <NUM> can be omitted and processing can be performed by irradiating the laser beam to the workpiece <NUM> which is fixed so as not to move.

The laser generator <NUM> is a light source of the laser beam and can generate a pulsed laser with a short time width by pulse oscillation. The time width of the pulsed laser is not particularly limited. The time width is a short time interval such as a nanosecond order, a picosecond order, or a femtosecond order, for example. The laser generator <NUM> may be configured to generate a CW laser by continuous wave oscillation.

The light guide device <NUM> guides the laser beam generated by the laser generator <NUM> to irradiate the workpiece <NUM>. The laser beam guided by the light guide device <NUM> is irradiated to an irradiated point <NUM> on a scanning line <NUM> defined on the surface of the workpiece <NUM>. As will be described in detail below, the light guide device <NUM> causes the irradiated point <NUM>, to which the workpiece <NUM> is irradiated by the laser beam, to move at a substantially constant speed along the straight scanning line <NUM>. In this way, the light scanning is realized.

Next, referring to <FIG>, the light guide device <NUM> will be described in detail. <FIG> is a schematic view of the light guide device <NUM>.

As shown in <FIG>, the light guide device <NUM> includes at least one reflection unit (light reflection device) <NUM>. In this embodiment, the light guide device <NUM> has one reflection unit <NUM>. The reflection unit <NUM> is disposed inside a housing <NUM> included by the light guide device <NUM>.

When the laser beam emitted from the laser generator <NUM> enters into the reflection unit <NUM>, the reflection unit <NUM> reflects the laser beam so as to guide the laser beam to the workpiece <NUM>. The laser beam incident from the laser generator <NUM> to the reflection unit <NUM> is hereinafter referred to as incident light. The reflection unit <NUM> is placed so as to be separated from the workpiece <NUM> by a predetermined distance.

The reflection unit <NUM> can scan optically by reflecting and deflecting the incident light. <FIG> and <FIG> show a scanning area <NUM>, which is an area in which the workpiece <NUM> is optically scanned by the reflection unit <NUM>. The scanning area <NUM> constitutes a scanning line <NUM>. The scanning area <NUM> is scanned by the reflection unit <NUM>.

Next, referring to <FIG>, the reflection unit <NUM> will be described in detail. <FIG> is a diagonal view of the reflection unit <NUM>. <FIG> is a cross-sectional view of the reflection unit <NUM>.

As shown in <FIG>, the reflection unit <NUM> includes a support plate (support member) <NUM>, reflection members <NUM>, a motor <NUM>, a prism <NUM>, and a scanning lens <NUM>.

The support plate <NUM> is a disc-shaped member and is rotatable with respect to a housing <NUM> described below. A first rotation shaft <NUM> is rotatably supported by the housing <NUM>. The support plate <NUM> is fixed to an axial end of the first rotation shaft <NUM>. An output shaft of the motor <NUM> is connected to the other end of the first rotation shaft <NUM> in the axial direction.

As shown in <FIG>, the reflection unit <NUM> includes a housing <NUM> in which the drive transmission mechanism of the reflection unit <NUM> is housed. The housing <NUM> is fixed at a suitable location on the housing <NUM> shown in <FIG>.

The housing <NUM> is formed in a hollow cylindrical shape with one axial side open. The support plate <NUM> is located so as to close the open side of the housing <NUM>. The first rotation shaft <NUM> is disposed so as to penetrate the housing <NUM>.

Each of the reflection members <NUM> is a member formed in a block shape. The reflection member <NUM> is rotatable with respect to the support plate <NUM>. Second rotation shafts <NUM> are rotatably supported by the support plate <NUM>. Each of the second rotation shafts <NUM> is directed parallel to the first rotation shaft <NUM> and is arranged to penetrate the support plate <NUM>.

The reflection member <NUM> is supported by the support plate <NUM> via a base portion <NUM> and the second rotation shaft <NUM>.

The base portion <NUM> is formed in a small disc shape as shown in <FIG>. The base portion <NUM> is fixed to one end of the second rotation shaft <NUM> in the axial direction as shown in <FIG>. The other end of the second rotation shaft <NUM> in the axial direction is located inside the housing <NUM>.

The above-described reflection member <NUM> is fixed to the base portion <NUM>. Accordingly, the reflection member <NUM> can rotate together with the base portion <NUM> and the second rotation shaft <NUM>.

The reflection members <NUM> can orbit around the first rotation shaft <NUM> together with the support plate <NUM> (revolution). At the same time, the reflection members <NUM> can rotate around the second rotation shaft <NUM> (rotation). In the following, the axial center of the first rotation shaft <NUM> may be referred to as a revolution axis, and the axial center of each of the second rotation shafts <NUM> may be referred to as a rotation axis. The drive mechanism of the reflection members <NUM> will be described later.

In the present embodiment, three reflection members <NUM> are provided. The three reflection members <NUM> are disposed on a surface in a side of the support plate <NUM> that is far from the housing <NUM>.

As shown in <FIG>, the three reflection members <NUM> are located in the support plate <NUM> so as to equally divide a circle having the first rotation shaft <NUM> as a center. Specifically, the three reflection members <NUM> are disposed at equal intervals (<NUM>° intervals) in the circumferential direction of the support plate <NUM>.

Each of the reflection members <NUM> reflects light so as to guide it to the scanning area <NUM>. As shown in <FIG>, the reflection member <NUM> has a first reflector <NUM> and a second reflector <NUM>. The first reflector <NUM> and the second reflector <NUM> are arranged in pairs across the second rotation shaft <NUM> (rotation axis).

To explain concretely, the reflection member <NUM> is formed in a rectangular block shape. In this reflection member <NUM>, the first reflector <NUM> is disposed on one of two opposing surfaces across the rotation axis, and the second reflector <NUM> is disposed on the other surface. The first reflector <NUM> and the second reflector <NUM> are formed symmetrically with respect to each other.

As will be described in detail below, angular speed of rotation of the support plate <NUM> is driven to be equal to twice angular speed of rotation of the reflection member <NUM>. Accordingly, while the support plate <NUM> rotates <NUM>°, the reflection member <NUM> rotates <NUM>°.

When viewing the reflection member <NUM> along the rotation axis, the first reflector <NUM> and the second reflector <NUM> are arranged to face opposite sides of each other.

<FIG> depicts the revolution and the rotation of the reflection member <NUM> when attention is focused on only one of the three reflection members <NUM>. To make the orientation of the reflection member <NUM> easier to understand, in <FIG>, an edge portion of the reflection member <NUM> on the side close to the first reflector <NUM> is drawn in a form with hatching. In <FIG>, the direction of the revolution and the direction of the rotation of the reflection member <NUM> are both counterclockwise.

As shown in <FIG>, the reflection member <NUM> rotates <NUM>° in conjunction with the <NUM>° rotation of the support plate <NUM>. Accordingly, every time the reflection member <NUM> revolves <NUM>°, it rotates <NUM>° and the orientation of the first reflector <NUM> and the second reflector <NUM> are swapped. Thus, for each <NUM>° rotation of the support plate <NUM>, the surface on which the incident light is reflected is alternately switched between the first reflector <NUM> and the second reflector <NUM>.

The first reflector <NUM> and the second reflector <NUM> each have a first reflection surface <NUM> and a second reflection surface <NUM>. The configurations of the first reflector <NUM> and the second reflector <NUM> are substantially identical to each other. Therefore, the configuration of the first reflector <NUM> will be described below as representative.

To explain concretely, a cross-sectional V-shaped groove is formed in the reflection member <NUM> to make the side far from the rotation axis open. The longitudinal direction of the groove is directed perpendicular to the rotation axis. The first reflection surface <NUM> and the second reflection surface <NUM> are formed on the inner wall of this groove. The first reflector <NUM> is made of the first reflection surface <NUM> and the second reflection surface <NUM>.

The first reflection surface <NUM> and the second reflection surface <NUM> are both formed in a planar shape. The first reflection surface <NUM> is disposed inclined with respect to a virtual plane perpendicular to the second rotation shaft <NUM>. The second reflection surface <NUM> is disposed inclined with respect to a virtual plane perpendicular to the second rotation shaft <NUM>.

As shown in <FIG>, the first reflection surface <NUM> and the second reflection surface <NUM> are inclined with respect to a virtual plane perpendicular to the second rotation shaft <NUM> in opposite directions and at an angle θ (specifically, <NUM>°) equal to each other. Accordingly, the first reflection surface <NUM> and the second reflection surface <NUM> are symmetrical with respect to a symmetry plane <NUM> perpendicular to the second rotation shaft <NUM>. The first reflection surface <NUM> and the second reflection surface <NUM> are arranged to form a V-shape with an angle of <NUM>°.

With this configuration, the incident light guided into the light guide device <NUM> is bent by the prism <NUM> and travels along a first light path L1 in a direction approaching the reflection unit <NUM>. The first light path L1 is orthogonal to the direction of the revolution axis of the reflection member <NUM>.

The three reflection members <NUM> are driven by the motor <NUM> to perform the revolution and the rotation, thereby moving across the first light path L1 in sequence. Accordingly, the three reflection members <NUM> hit the incident light along the first light path L1 in order and reflect the light.

Around the timing when the reflection member <NUM> which revolves is closest to the upstream side of the first light path L1, the first reflection surface <NUM> that belongs to the first reflector <NUM> or the second reflector <NUM> is positioned to overlap with the first light path L1 as shown in <FIG>. Accordingly, the incident light is reflected by the first reflection surface <NUM>, and then reflected by the second reflection surface <NUM>.

When the reflection member <NUM> performs the revolution and the rotation with being hit by the incident light as shown in <FIG>, the directions of the first reflection surface <NUM> and the second reflection surface <NUM> change continuously. Accordingly, the direction of the light emitted from the second reflection surface <NUM> smoothly changes as shown by the white arrow in <FIG>. Thus, a deflection of the emitted light is realized.

Since the first reflection surface <NUM> and the second reflection surface <NUM> are arranged in a V-shape, as the reflection member <NUM> performs the revolution and the rotation, the emitted light from the reflection member <NUM> is deflected along a plane perpendicular to the rotation axis. This plane is offset in the direction of the second rotation shaft <NUM> (in other words, in the direction of the first rotation shaft <NUM>) with respect to the first light path L1. This allows the light reflected by the second reflection surface <NUM> to be directed to the workpiece <NUM> through a second optical path L2, which is offset with respect to the first light path L1.

The incident light enters into the reflection unit <NUM> in a direction perpendicular to the rotation axis and the revolution axis. When a phase of the revolution of the reflection member <NUM> is completely coincident with the direction of the incident light, the first reflection surface <NUM> and the second reflection surface <NUM> are orthogonal to the incident light when viewed along the second rotation shaft <NUM>. Accordingly, at this time, the incident light is reflected twice by the reflection member <NUM> so as to be folded back as shown in <FIG>, and is emitted along the second light path L2 which is parallel and opposite to the direction of the first light path L1.

Thus, the incident light is deflected by being reflected by the first reflection surface <NUM> and the second reflection surface <NUM>. Here, as shown in <FIG>, a mirror image of the symmetry plane <NUM> about the first reflection surface <NUM> and a mirror image of the symmetry plane <NUM> about the second reflection surface <NUM> are considered. Both of the two mirror images equal to a plane <NUM> located inside the reflection member <NUM>. From the viewpoint of light path length, the case where the incident light is reflected with offset by the first reflection surface <NUM> and the second reflection surface <NUM> and the case where the incident light is reflected without offset by the plane <NUM> are equivalent. In this sense, the virtual plane <NUM> described above can be said to be an apparent reflection surface.

The plane <NUM> will now be described from another aspect. In the following, a light path from a point at which the incident light is reflected by the first reflection surface <NUM> to a point at which it is reflected by the second reflection surface <NUM> is referred to as an intermediate light path L3. The bisector point of the intermediate light path L3 is located on the symmetry plane <NUM>.

As shown by the dashed line in <FIG>, consider the case where the first light path L1 of the incident light is extended from the first reflection surface <NUM> to plunge into the inside of the reflection member <NUM>. A point <NUM> at the end of an extension line <NUM>, which extends the first light path L1 of the incident light by a length D1, which is half the length of the intermediate light path L3, is located on the plane <NUM>.

Similarly, consider the case where the second light path L2 of the incident light is extended from the second reflection surface <NUM> to plunge into the inside of the reflection member <NUM>. A point <NUM> at the end of an extension line <NUM>, which extends the second light path L2 of the incident light by the length D1, which is half the length of the intermediate light path L3, is located on the plane <NUM>.

<FIG> shows a state in which the direction of the second light path L2 is the center of the deflection angle range. However, no matter in which direction the incident light is deflected by the reflection member <NUM>, the ends of the extension lines <NUM>, <NUM> are always located in the plane <NUM>.

This plane <NUM> is also the plane of reference in which the first reflector <NUM> and the second reflector <NUM> are symmetrically arranged. Accordingly, although the plane <NUM> is shown in <FIG> in relation to the first reflector <NUM>, the plane <NUM> is common to both the first reflector <NUM> and the second reflector <NUM>. And in the present embodiment, the rotation axis of the reflection member <NUM> (in other words, the axial center of the second rotation shaft <NUM>) is arranged to be included in this plane <NUM>.

Accordingly, deflecting the incident light at the first reflector <NUM> and the second reflector <NUM> of the reflection member <NUM> is substantially the same as deflecting the incident light by reflection surfaces arranged on the front and back sides of the zero-thickness plane <NUM> that performs the rotation and the revolution integrally with the reflection member <NUM>. <FIG> illustrates the relationship between the reflection member <NUM> which rotates and revolves and the plane <NUM>.

The prism <NUM> comprises a suitable optical element. The prism <NUM> is disposed at an upstream side of the first light path L1 than the reflection member <NUM>. The prism <NUM> allows the laser beam from the laser generator <NUM> to be guided to the reflection member <NUM>.

The scanning lens <NUM> is a free-form surface lens, for example, a known fθ lens can be used. The scanning lens <NUM> is disposed between the reflection member <NUM> and the scanning area <NUM>. By this scanning lens <NUM>, a focal distance can be made constant in the center and the peripheral portions of the scanning area.

The motor <NUM> generates a driving force for the revolution and the rotation of the reflection member <NUM>. The driving force of the motor <NUM> is transmitted to a planetary gear train through the output shaft of the motor <NUM>, thereby rotating the support plate <NUM> and the reflection members <NUM>. The motor <NUM> is an electric motor in this embodiment, but is not limited thereto.

Next, referring to <FIG> and <FIG>, a drive mechanism for rotating the support plate <NUM> and the reflection members <NUM> will be described. <FIG> is a cross-sectional view of the reflection unit <NUM> cut along a plane perpendicular to the revolution axis.

As shown in <FIG>, the center of the support plate <NUM> is fixed to an axial end of the first rotation shaft <NUM>. The output shaft of the motor <NUM> is connected to the other end of the first rotation shaft <NUM> in the axial direction.

Second rotation shafts <NUM> are disposed at positions radially outside the center of the support plate <NUM>. Each of the second rotation shafts <NUM> is rotatably supported by the support plate <NUM>. An axial end portion of the second rotation shaft <NUM> is disposed outside the housing <NUM> and is fixed to the base portion <NUM>. The other axial end portion of the second rotation shaft <NUM> in the axial direction is disposed inside the housing <NUM>.

As shown in <FIG>, a planetary gear <NUM> is fixed to each of the second rotation shafts <NUM> inside the housing <NUM>. The planetary gears <NUM> are coupled with a sun gear <NUM> provided around the first rotation shaft <NUM> via counter gears <NUM>. The sun gear <NUM> is fixed to the housing <NUM>. Each of the counter gear <NUM> is rotatably supported by the support plate <NUM>.

As a result, when the motor <NUM> is driven, the driving force of the motor <NUM> is transmitted to the first rotation shaft <NUM>, causing the support plate <NUM> to rotate. The rotation of the support plate <NUM> causes the shafts of the counter gears <NUM> and the shafts of the planetary gears <NUM> (the second rotation shafts <NUM>) to move around the sun gear <NUM>. At this time, the counter gears <NUM> meshing with the sun gear <NUM> rotate, and the planetary gears <NUM> meshing with the counter gear <NUM> also rotate. Accordingly, the reflection members <NUM>, which are fixed to the planetary gears <NUM> via the second rotation shafts <NUM>, perform the revolution and the rotation simultaneously.

The sun gear <NUM> is fixed to the housing <NUM> and the counter gears <NUM> are interposed between the planetary gears <NUM> and the sun gear <NUM>. Accordingly, a direction of rotation of the support plate <NUM>, which is a planetary carrier, and a direction of rotation of the second rotation shafts <NUM> (the reflection members <NUM>) are in the same direction. In addition, the number of teeth of each of the planetary gears <NUM> is twice the number of teeth of the sun gear <NUM>. As a result, the revolution angular velocity of the reflection member <NUM> is equal to twice the rotation angular velocity of the reflection member <NUM>.

Next, with reference to <FIG>, the relationship between the revolution angular velocity and the rotation angular velocity of the reflection members <NUM> will be described in detail.

In <FIG>, a trajectory of the second rotation shaft <NUM> associated with the rotation of the support plate <NUM> is shown as a revolution circle <NUM>. The center of the revolution circle <NUM> is located at an intersection point (origin O) of the X-axis and the Y-axis extending in a direction perpendicular to each other. The origin O corresponds to the revolution axis of the reflection members <NUM>. As described above, the deflection of the light at the reflection member <NUM> can be considered to be substantially the same as the deflection by reflecting the light at the aforementioned plane <NUM>. Accordingly, in <FIG>, the reflection member <NUM> is represented by a straight line indicating the plane <NUM>, which is an equivalent virtual reflection surface.

The rotation axis of the reflection member <NUM> is located at an arbitrary point on the revolution circle <NUM>. Here, consider a state in which the rotation axis of the reflection member <NUM> is at the position of a point P and the orientation of the reflection surface of the reflection member <NUM> is perpendicular to the X-axis. At this state, light incident toward the origin O in the direction of the X-axis is reflected by the reflection member <NUM> at the point P. When viewed two-dimensionally as shown in <FIG>, the light path of the reflected light matches the light path of the incident light.

Suppose that the position of the rotation axis of the reflection member <NUM> changes by an angle θ and moves from the point P to a point Q as the support plate <NUM> rotates. To ensure that the point at which the incident light hits the reflection member <NUM> does not change from the point P, even if the reflection member <NUM> revolves in this manner, consider what the angle of the rotation of the reflection member <NUM> must be in relation to the angle of the revolution.

In order for the incident light to be reflected at the point P even if the rotation axis of the reflection member <NUM> is at the point Q, the orientation of the reflection member <NUM> must match an orientation of the line drawn from the point Q to the point P.

The midpoint of a straight line connecting the point P and the point Q is defined as M. Also, consider a straight line passing through the point Q and extending parallel to the Y-axis, and the intersection point of this line with the X-axis is defined as N.

Since the points P and Q are both on the circumference of the revolution circle <NUM>, the triangle OPQ is an isosceles triangle. Therefore, the angle OPM formed by the line OP and the line PM is equal to the angle OQM formed by the line OQ and the line QM. The straight line OM and the straight line PQ are orthogonal. Also, the straight line OP is orthogonal to the straight line QN.

If we focus on the triangle OQM and the triangle NQP, the two angles of the triangle are equal to each other as described above. Therefore, triangle OQM and triangle NQP are geometrically similar.

Therefore, the angle QOM, formed by the line QO and the line OM, is equal to the angle PQN, formed by the line PQ and the line QN. The angle QOP formed by the straight line QO and the straight line OP is θ. Therefore, the angle QOM is θ/<NUM> and the angle PQN is also θ/<NUM>.

From this result, it can be seen that if the reflection member <NUM> performs the revolution and the rotation simultaneously so that the revolution angular velocity is twice the rotation angular velocity, the length of the optical path can be kept constant because the reflection member <NUM> crosses the light path so that it always hits the incident light at point P.

Thus, in the present embodiment, the incident light is reflected and deflected by rotating the reflective member <NUM> having the reflection surfaces <NUM>, <NUM>. The reflection member <NUM> is rotatably driven at constant angular velocity and does not perform a reciprocating motion (acceleration/deceleration) like a mirror galvanometer. Accordingly, it is possible to avoid narrowing the scanning area <NUM> in which the movement speed of the irradiated point <NUM> can be constant, and to suppress a decrease in a processable range of the workpiece <NUM> by the light. Further, the combination of the revolution and the rotation of the reflection members <NUM> can prevent the fluctuations of the point at which the reflection member <NUM> hits the incident light. Therefore, the light can be guided to the scanning lens <NUM> in an ideal state in the same way as with the mirror galvanometer. Thus, it is possible to obtain a light reflection device having both a high irradiation rate, which is an advantage of a polygon mirror, and a resistance in reflection point fluctuation, which is an advantage of a mirror galvanometer.

As described above, the reflection unit <NUM> of the present embodiment comprises reflection members <NUM> having the reflection surfaces <NUM>, <NUM> each of which is formed in a planar shape. The reflection surfaces <NUM>, <NUM> reflect incident light. Each of the reflection members <NUM> performs the revolution and the rotation simultaneously. The direction of the revolution of the reflection member <NUM> and the direction of the rotation of the reflection member <NUM> are the same. The angular velocity of the revolution of the reflection member <NUM> is equal to twice the angular velocity of the rotation of the reflection member <NUM>.

As a result, the reflection position of the light relative to the incident light is constant in regards to the reflection member <NUM>, and the reflection position of the light is prevented from fluctuating. Accordingly, the distortion of scanning can be reduced. In comparison with the mirror galvanometer, the deflection is realized by rotation of the reflection member <NUM> instead of reciprocating motion. Therefore, it is easy to perform the scanning at a constant speed.

In the reflection unit <NUM> of this embodiment, the reflection surfaces <NUM>, <NUM> are arranged in pairs across the rotation axis of the reflection member <NUM>.

The reflection member <NUM> changes its orientation by rotating <NUM>° for every <NUM>° of the revolution. The reflection surfaces <NUM>, <NUM>, whose orientations are <NUM>° different from each other, are arranged in pairs on the reflection member <NUM>. As a result, when the reflection member <NUM> crosses the light path of the incident light, one of the two reflection surfaces effectively reflects the light. Accordingly, the incident light can be efficiently guided to the workpiece <NUM>.

The reflection unit <NUM> of the present embodiment is provided with three reflection members <NUM>. The revolution axes of the three reflection members <NUM> are coincident. The three reflection members <NUM> are arranged to divide the circle centered on the revolution axis at equal angular intervals.

This allows the incident light to be directed to the workpiece <NUM> with even greater efficiency.

The reflection unit <NUM> of the present embodiment comprises the planetary gear train. The planetary gear train causes the reflection members <NUM> to perform the revolution and the rotation.

As a result, a complex operation combining the revolution and the rotation of the reflection members <NUM> can be realized with a simple configuration.

In the reflection unit <NUM> of the present embodiment, the reflection member <NUM> reflects the light so as to deflect the light along a plane perpendicular to the rotation axis, as shown in <FIG>. This plane is offset in the direction of the rotation axis with respect to the incident light which enters into the reflection member <NUM>.

This allows for a layout in which the reflected light reflected by the reflection member <NUM> does not interfere with an optical member or the like used to guide the incident light to the reflection unit <NUM>.

In the present embodiment, the first reflection surface <NUM> and the second reflection surface <NUM> are formed on each of the reflection members <NUM>. The first reflection surface <NUM> is formed in a planar shape inclined with respect to a plane perpendicular to the rotation axis of the reflection member <NUM>. The second reflection surface <NUM> is formed in a planar shape inclined with respect to a plane perpendicular to the rotation axis of the reflection member <NUM>. The direction in which the first reflection surface <NUM> is inclined with respect to the plane perpendicular to the rotation axis and the direction in which the second reflection surface <NUM> is inclined with respect to the plane perpendicular to the rotation axis are opposite. The incident light is reflected by the first reflection surface <NUM> and then reflected by the second reflection surface <NUM>. The first reflection surface <NUM> and the second reflection surface <NUM> are formed to be symmetrical to each other with respect to the symmetry plane <NUM>. The mirror image of the symmetry plane <NUM> with respect to the first reflection surface <NUM> and the mirror image of the symmetry plane <NUM> with respect to the second reflection surface <NUM> are identical to each other and in the plane <NUM>. The rotation axis of the reflection member <NUM> is included in the plane <NUM> of the mirror images.

This allows for a simple configuration in which the incident light is reflected while offset at the reflection member <NUM> and the reflection position of the light with respect to the incident light is constant in regards to the reflection member <NUM>.

In the light guide device <NUM> of the present embodiment, the angle θ at which the first reflection surface <NUM> is inclined with respect to the plane perpendicular to the rotation axis is <NUM>°. The angle θ at which the second reflection surface <NUM> is inclined with respect to the plane <NUM> perpendicular to the rotation axis is <NUM>°.

This allows for a simple configuration of the reflection member <NUM>.

The light guide device <NUM> of the present embodiment includes the reflection unit <NUM> of the above-described configuration. The incident light is deflected by the reflection unit <NUM> to scan the workpiece <NUM>.

This allows for scanning with minimal distortion.

The light guide device <NUM> of the present embodiment includes the scanning lens <NUM>. The scanning lens <NUM> is placed on the light path from the reflection member <NUM> to the scanning area <NUM>.

This allows the focal distance to be aligned over the entire scanning area. Also, the light can be guided to the scanning lens <NUM> in an ideal state.

Next, a first modification of the drive mechanism of the support plate <NUM> and the reflection member <NUM> will be described. In the description of this modification, members identical or similar to those of the above-described embodiment are given the same reference numerals on the drawing, and descriptions thereof may be omitted.

In the modification shown in <FIG>, a ring gear <NUM> is fixed near the outer circumference of the support plate <NUM>. The ring gear <NUM> meshes with a drive gear <NUM> fixed to the output shaft of the motor <NUM>. The rest of the configuration is substantially the same as in <FIG>.

In this modification, the support plate <NUM> can also be rotated by driving the motor <NUM> to cause the reflection member <NUM> to perform the revolution and the rotation.

Next, a second modification of the drive mechanism for the support plate <NUM> and the reflection member <NUM> will be described. In the description of this modification, members identical or similar to those of the above-described embodiment are given the same reference numerals on the drawing, and descriptions thereof may be omitted.

In the modification shown in <FIG>, as similar as in <FIG>, a ring gear <NUM> is fixed near the outer circumference of the support plate <NUM>.

A two-diameter gear <NUM> is rotatably supported inside the housing <NUM>. The two-diameter gear <NUM> includes a large diameter gear 96a and a small diameter gear 96b. The large diameter gear 96a and the small diameter gear 96b rotate integrally with each other. The large diameter gear 96a meshes with a drive gear <NUM> fixed to the output shaft of the motor <NUM>. The small diameter gear 96b meshes with the ring gear <NUM>.

A transmission gear <NUM> is rotatably supported in the housing <NUM>. The transmission gear <NUM> meshes with the large diameter gear 96a included by the two-diameter gear <NUM>.

Unlike the above-described embodiment and the like, the sun gear <NUM> is rotatably supported by the housing <NUM>. A transmission gear <NUM> is connected to the sun gear <NUM> via a transmission shaft <NUM>. The sun gear <NUM> rotates integrally with the transmission shaft <NUM>.

In this modification, the counter gear <NUM> is omitted. The sun gear <NUM> is directly engaged with the planetary gear <NUM> without the counter gear <NUM>.

With this configuration, when the motor <NUM> is driven, the two-diameter gear <NUM> rotates. As a result, the ring gear <NUM> is driven by the small diameter gear 96b, and the support plate <NUM> rotates. At the same time, the transmission gear <NUM> is driven by the large diameter gear 96a, and the sun gear <NUM> rotates.

The sun gear <NUM> rotates at greater angular velocity than the support plate <NUM> and in the same direction as the support plate <NUM>. As a result, the planetary gear <NUM> can perform the rotation in the same direction as the revolution. By determining the number of teeth of the two-diameter gear <NUM> or the like according to a known formula, the configuration can be made to perform the revolution and the rotation simultaneously so that the angular velocity of the revolution of the reflection member <NUM> is twice the angular velocity of the rotation.

Next, with reference to <FIG> and <FIG>, a second embodiment of the light guide device <NUM> will be described. In the description of this embodiment, members identical or similar to those of the above-described embodiment are given the same reference numerals on the drawing, and descriptions thereof may be omitted.

The present embodiment differs from the first embodiment in that the light guide device <NUM> comprises a plurality of reflection units <NUM>. This embodiment is used, for example, to process a workpiece <NUM> that is longer in the main scanning direction than the first embodiment.

As shown in <FIG> and <FIG>, the light guide device <NUM> is provided with a plurality of the reflection units <NUM>. Two reflection units <NUM> are placed in the light guide device <NUM> of this embodiment. Each of the reflection units <NUM> reflects a laser beam incident from the laser generator <NUM> and guides it to the workpiece <NUM>.

The two reflection units <NUM> are lined up in a straight line along the main scanning direction. The direction in which the reflection units <NUM> are lined up also corresponds to the longitudinal direction of the scanning line <NUM>. Each of the two reflection units <NUM> is disposed at a position where the distance from the scanning line <NUM> is substantially equal.

Hereafter, with respect to the plurality of reflection units <NUM>, the reflection unit <NUM> located upstream side in the traveling direction of the incident light (the side which is close to the laser generator <NUM>) may be referred to as a first reflection unit <NUM>. The reflection unit <NUM> located downstream side in the traveling direction of the incident light (the side which is far from the laser generator <NUM>) may be referred to as a second reflection unit <NUM>.

Each of the reflection units <NUM> can scan optically by reflecting and deflecting the laser beam. The area (scanning area) <NUM> in which the workpiece <NUM> is optically scanned by the first reflection unit <NUM> is different from the scanning area <NUM> by the second reflection unit <NUM>. The two scanning areas <NUM>, <NUM> are located in a straight arrangement. A set of the two scanning areas <NUM>, <NUM> constitutes a scanning line <NUM>.

Each of the reflection units <NUM> can be iteratively switched between a reflecting state, in which it reflects the incident light and performs scanning, and a passing state, in which it does not reflect the incident light and passed the light downstream. When the reflection unit <NUM> is in the reflecting state, the corresponding scanning area (e.g., the scanning area <NUM> in the case of the first reflection unit <NUM>) is scanned by light. When the reflection unit <NUM> is in the passing state, the corresponding reflection unit <NUM> does not perform the light scanning.

Timing at which each of the reflection units <NUM> is in the reflecting state differs among the plurality of the reflection units <NUM>. As a result, the plurality of scanning areas are scanned respectively by switching the reflection units <NUM> that enter the reflecting state.

In the present embodiment, two reflection members <NUM> are provided for one reflection unit <NUM>. The two reflection members <NUM> are respectively arranged to divide <NUM>° equally in the support plate <NUM>. Specifically, the two reflection members <NUM> are disposed such that one reflection member <NUM> is displaced <NUM>° with respect to the other reflection member <NUM> in the circumferential direction of the support plate <NUM>.

On the support plate <NUM>, the two reflection members <NUM> are disposed at positions corresponding to mutually opposite sides of a regular polygon (specifically, a regular quadrilateral). Accordingly, in the two reflection members <NUM>, the central angle corresponding to one of the reflection members <NUM> is <NUM>°. The reflection member <NUM> is not disposed at a position corresponding to a side other than the above-described opposing sides.

When the two reflection members <NUM> each move in accordance with the rotation of the support plate <NUM>, the state in which the reflection member <NUM> is hit by the laser beam which enters into the reflection unit <NUM> and travels along the first light path L1 and the state in which the reflection member <NUM> is not hit by the laser beam are alternately switched. As shown in the first reflection unit <NUM> in <FIG>, the state in which any of the two reflection members <NUM> is hit by the incident light is the reflecting state described above. As shown in the first reflection unit <NUM> of <FIG>, the state in which none of the two reflection members <NUM> is hit by the incident light is the passing state described above.

The first light path L1 is orthogonal to the first rotation shaft <NUM> and the second rotation shaft <NUM>. The two reflection members <NUM> are arranged with a phase difference of <NUM>° with respect to each other. Accordingly, of the two reflection members <NUM> placed across the first rotation shaft <NUM>, only the reflection member <NUM> positioned on the side close to the upstream side of the first light path L1 is to be hit by the incident light.

The light guide device <NUM> of the present embodiment is constituted by the two reflection units <NUM> configured as described above being provided for the incident light traveling from the laser generator <NUM> through appropriate prisms <NUM>. In the two reflection units <NUM>, the revolution axis and the rotation axis of the reflection members <NUM> are parallel to each other. The reflection members <NUM> perform the revolution and the rotation in the same direction. The angular velocity of the revolution of the reflection member <NUM> is equal to twice the angular velocity of the rotation of the reflection member <NUM>.

The reflection members <NUM> each perform the revolution with angular velocity equal to that of the revolution of the reflection member <NUM> in the other reflection unit <NUM>, in the same direction, and with a predetermined angular difference of the rotational phase (<NUM>° in this embodiment). This allows the timing at which the reflection member <NUM> is hit by the incident light to be different between the two reflection units <NUM>.

The above-described revolution and rotation of the reflection members <NUM> in the plurality of reflection units can be realized, for example, by controlling the motors(not shown) provided by each of the two reflection units <NUM> to rotate synchronously. However, for example, the two reflection units <NUM> can also be driven by a common motor.

<FIG> shows a case in which, of the two reflection units <NUM>, the first reflection unit <NUM> enters the reflecting state and the second reflection unit <NUM> enters the passing state. <FIG> shows a case in which, as a result of the revolution and the rotation of the reflection members <NUM> of each reflection unit <NUM> from the state of <FIG>, the first reflection unit <NUM> enters the passing state and the second reflection unit <NUM> enters the reflecting state. In this way, the reflection unit <NUM> that performs light scanning can be switched sequentially to realize light scanning along the scanning line <NUM> that is longer than the first embodiment as a whole.

As described above, in the laser processing device <NUM> of the present embodiment, the reflection members <NUM> of the reflection unit <NUM> perform the revolution and the rotation simultaneously, so that the light guide device <NUM> is switched between the reflecting state in which the reflection surface <NUM> reflects the incident light by being hit by the incident light and the passing state in which the reflection surface <NUM> lets the incident light pass through without being hit by the incident light. The timing of being in the reflecting state differs among the plurality of light guide devices <NUM>. The single straight scanning line <NUM> is formed by the set of scanning areas <NUM>, <NUM> corresponding to the plurality of light guide devices <NUM>.

This allows scanning along a long scanning line to be realized.

Next, with reference to <FIG>, a rotation mirror <NUM>, which is a specially shaped reflection member, will be described. In the description of this embodiment, members identical or similar to those of the above-described embodiment are given the same reference numerals on the drawing, and descriptions thereof may be omitted.

The rotation mirror <NUM> includes a first regular polygon pyramid <NUM> and a second regular polygon pyramid <NUM>. In this embodiment, the two regular polygonal pyramids <NUM>, <NUM> are formed as regular octagonal pyramids, but are not limited thereto.

The two regular polygonal pyramids <NUM>, <NUM> are arranged facing each other with their axes <NUM> coinciding with each other. The two regular polygonal pyramids <NUM>, <NUM> are coupled to each other by an intermediate portion <NUM>. Accordingly, each of the two regular polygonal pyramids <NUM>, <NUM> is formed in a substantially polygonal trapezoidal pyramid shape.

A transmission shaft <NUM> is attached to the rotation mirror <NUM>. By transmitting a driving force of a drive unit which is not shown (specifically, a motor) to this transmission shaft <NUM>, the rotation mirror <NUM> rotates. The rotation mirror <NUM> and the drive unit constitute a reflecting device that reflects light while deflecting the light. A rotation axis is coincident with the axis <NUM> of the two regular polygonal pyramids <NUM>, <NUM>.

The sides of the two regular polygonal pyramids <NUM>, <NUM> are light reflection surfaces <NUM> each of which is formed in a planar shape. The light reflection surfaces <NUM> are arranged side by side around the axis <NUM>. Each of the light reflection surfaces <NUM> is inclined with respect to the axis <NUM>.

The first regular polygon pyramid <NUM> includes a first base surface <NUM>. The second regular polygon pyramid <NUM> includes a second base surface <NUM>. The first base surface <NUM> and the second base surface <NUM> are regular polygons and are perpendicular to the axis <NUM>.

In this embodiment, the first regular polygon pyramid <NUM> and the second regular polygon pyramid <NUM> are identical in shape. Since the two regular polygonal pyramids <NUM>, <NUM> are regular octagonal pyramids, the first base surface <NUM> and the second base surface <NUM> are both regular octagons. Therefore, the number of sides of the regular polygon is equal between the first base surface <NUM> and the second base surface <NUM>.

The two regular polygonal pyramids <NUM>, <NUM> are coupled by an intermediate portion <NUM> such that the phases of the regular octagons that the two base surfaces <NUM>, <NUM> have are matched with each other.

<FIG> shows a virtual plane <NUM> along which the rotation mirror <NUM> is cut. This virtual plane <NUM> is defined to include the axis <NUM> and to include the midpoints <NUM>, <NUM> of one of the sides of the regular octagon of the base surfaces <NUM>, <NUM>.

When the base angle in the case which the first regular polygon pyramid <NUM> is cut along the virtual plane <NUM> is defined as α, and the base angle when the second regular polygon pyramid <NUM> is cut along the virtual plane <NUM> is defined as β, the relationship α + β = <NUM>° is established in the rotation mirror <NUM> of the present embodiment. In the present embodiment, α = β = <NUM>°, but this is not limited thereto. For example, the relationship may be α = <NUM>° and β = <NUM>°, and the like.

When the distance between the first base surface <NUM> and the second base surface <NUM> is defined as D2, the distance between the midpoint <NUM> of one side of the regular polygon of the first base surface <NUM> and the axis <NUM> is defined as D3, and the distance between the midpoint <NUM> of one side of the regular polygon of the second base surface <NUM> and the axis <NUM> is defined as D4, the relationship D2 = D3 × tan α + D4 × tan β is established in the present embodiment.

With the above configuration, when considering the contour of the rotation mirror <NUM> which is cut along the virtual plane <NUM>, the straight line <NUM> corresponding to the light reflection surface <NUM> of the first regular polygon pyramid <NUM> and the straight line corresponding to the light reflection surface <NUM> of the second regular polygon pyramid <NUM> are perpendicular to each other.

Furthermore, since the relationship of the above equation is established between the distances D2, D3, and D4, if the two straight lines <NUM> and <NUM> are extended as shown by the chain lines in <FIG>, their intersection point will be located on the axis <NUM>. This is evident by considering two right-angled triangles and the relationship between tan α and tan β.

By the way, in the reflection member <NUM> of <FIG> in the aforementioned embodiment, the rotation axis is arranged to be included in the virtual plane <NUM>, which is the apparent reflection surface of the light. The configuration of the rotation mirror <NUM> of <FIG> is an extension of the above idea to a regular polygonal pyramid mirror.

In the rotation mirror <NUM> of <FIG>, consider a case where the light is irradiated from an irradiation device to a light reflection surface <NUM> so as to intersect an axis <NUM>. The incident light (e.g., laser beam) is reflected by the light reflection surface <NUM> of the first regular polygon pyramid <NUM>, and then reflected by the light reflection surface <NUM> of the second regular polygon pyramid <NUM>, and then emitted.

Each of the light reflection surfaces <NUM> disposed on a side of the rotation mirror <NUM> can be associated with a respective side of the regular polygon in the base surfaces <NUM>, <NUM>. In the following, the side of the regular polygon described above that corresponds to the light reflection surface <NUM> that is hit by the light may be referred to as a corresponding side.

Here, virtually consider a plane <NUM> of zero thickness that is located to include the axis <NUM> and rotates with the rotation mirror <NUM>. This plane <NUM> is parallel to the corresponding side described above. Deflecting the incident light by two reflections with the rotation mirror <NUM> including a pair of regular polygonal pyramid portions is equivalent to deflecting the incident light by one reflection by the plane <NUM>.

Accordingly, the reflection position of the light relative to the incident light is constant in regards to the rotation mirror <NUM>. As a result, it is possible to prevent the reflection position of the light from fluctuating.

In the present embodiment, the rotation mirror <NUM> is simply rotated via the transmission shaft <NUM>, and the axis <NUM>, which is the center of rotation, is not moved. In the present embodiment, a large-scale rotating device that combines the revolution and the rotation is unnecessary, so that simplification and downsizing of the configuration can be easily realized.

This rotation mirror <NUM> can be used, for example, together with the above-described motor <NUM>, the housing <NUM>, the scanning lens <NUM>, the laser generator <NUM>, and the like to configure the light guide device <NUM> and the laser processing device <NUM> shown in <FIG>. As described above, in this laser processing device, the reflection position of the light by the rotation mirror <NUM> is substantially constant. Therefore, by using an fθ lens as the scanning lens <NUM>, scanning at the irradiated point <NUM> at a constant speed of the focus point is realized. In comparison with the mirror galvanometer, the deflection is achieved by the rotation of the rotation mirror <NUM> instead of reciprocating motion. Accordingly, it is easier to perform scanning at a constant speed.

As described above, the laser processing device of the present embodiment is provided with the rotation mirror <NUM>, the motor, and the irradiation device. The motor rotates the rotation mirror <NUM>. The irradiation device irradiates the light onto the rotation mirror <NUM>. The rotation mirror <NUM> comprises the first regular polygon pyramid <NUM> and the second regular polygon pyramid <NUM>. The second regular polygon pyramid <NUM> is arranged facing the first regular polygon pyramid <NUM> with the axis <NUM> coincident with the first regular polygon pyramid <NUM>. Side surfaces of each of the first regular polygon pyramid <NUM> and the second regular polygon <NUM> are light reflection surfaces <NUM> each of which is formed in a planar shape. The number of sides of the regular polygons is equal in the first base surface <NUM> that the first regular polygon pyramid <NUM> has and the second base surface <NUM> that the second regular polygon pyramid <NUM> has. The first base surface <NUM> and the second base surface <NUM> are both arranged perpendicular to the axis <NUM>. The first regular polygon pyramid <NUM> and the second regular polygon pyramid <NUM> are rotated integrally with each other around the axis <NUM> as the rotation axis by the motor while the phase of the regular polygon of the first base surface <NUM> and the phase of the regular polygon of the second base surface <NUM> are matched with each other. The base angle of the first regular polygon pyramid <NUM> is defined as α° when the first regular polygon pyramid <NUM> is cut along a virtual plane <NUM> that includes the axis <NUM> and the midpoint <NUM> of one of the sides of the regular polygon of the first base surface <NUM>. The base angle of the second regular polygon pyramid <NUM> is β = (<NUM> - α)° when the second regular polygon pyramid <NUM> is cut along a virtual plane <NUM> that includes the axis <NUM> and the midpoint <NUM> of one of the sides of the regular polygon of the second base surface <NUM>. The distance D2 between the first base surface <NUM> and the second base surface <NUM> is equal to the sum of the distance D3 between the midpoint <NUM> of one side of the regular polygon of the first base surface <NUM> and the axis <NUM> multiplied by tan α, and the distance D4 between the midpoint of one side of the regular polygon of the second base surface <NUM> and the axis <NUM> multiplied by tan(<NUM>-α). The irradiation device irradiates the light in a direction intersecting the axis <NUM> of the rotating mirror <NUM>.

As a result, the reflection position of the light relative to the incident light is constant in regards to the rotation mirror <NUM>, and the reflection position of the light is prevented from fluctuating with rotation. Accordingly, the distortion of scanning can be reduced.

In the light guide device of this embodiment, the base angle α is <NUM>°.

This allows the rotation mirror <NUM> to have a simple shape. Also, a concise light path layout can be realized.

Although the preferred embodiment and the modifications of the present invention have been described above, the configurations described above may be modified as follows, for example.

The number of the reflection members <NUM> provided to the support plate <NUM> in the reflection unit <NUM> is not limited to three as in the first embodiment, but can be, for example, four or five.

The number of the reflection units <NUM> can be determined according to the shape of the irradiated object or the like, and can be, for example, three, four, or five instead of two as in the second embodiment.

The first reflector <NUM> and the second reflector <NUM> in the reflection member <NUM> may be realized by a prism.

The optical scanning device to which the light guide device <NUM> is applied is not limited to the laser processing device <NUM>, but may be, for example, an image forming device.

In the third embodiment, instead of the regular <NUM>-pyramid, for example, a regular <NUM>-pyramid, a regular <NUM>-pyramid, or the like can be used as the first regular polygon pyramid <NUM> and the second regular polygon <NUM>. The sizes of the first base surface <NUM> and the second base surface <NUM> can be configured to be different from each other.

In the rotation mirror <NUM> of the third embodiment, any shape can be adopted for the portion that does not reflect light. Although the first regular polygon pyramid <NUM> and the second regular polygon pyramid <NUM> shown in <FIG> are actually regular polygonal trapezoidal pyramid shapes, they are included in the regular polygonal pyramid as long as the portions that reflect light are regular polygonal pyramid shapes. The designations "base surface" and "base angle" are not intended to limit the orientation of the regular polygonal pyramid. The rotation mirror <NUM> may be used with its axis <NUM> in any orientation.

Claim 1:
A light reflection device (<NUM>) comprising:
a reflection member (<NUM>) having a reflection surface that is formed in a planar shape for reflecting incident light, the reflection member configured to perform a revolution and a rotation simultaneously; and motor (<NUM>), wherein
a direction of the revolution of the reflection member and a direction of the rotation of the reflection member are the same, and
the motor is configured to drive the reflection member so that the angular velocity of the revolution of the reflection member is equal to twice angular velocity of the rotation of the reflection member.