Laser marker

Abstract

The purpose of the present invention is to provide a laser marker with which a reduction in size can be achieved. A laser marker 10 has a light-projecting part 18 and a rotating part 20. The rotating part 20 includes a driven gear 36 that rotates integrally with the light-projecting part 18, a drive gear 56, a motor 42, a knob 32, a planetary gear mechanism 58, a first drive wheel 54 that rotates integrally with a sun gear 64, a second drive wheel 60 that has external teeth provided over 360 degrees on an outer peripheral surface of a ring gear 66, a motor worm 42c provided on a motor shaft 42b of the motor 42, and a knob worm 32b provided on a knob shaft 32a of the knob 32. The first drive wheel 54 meshes with the motor worm 42c, and the second drive wheel 60 meshes with the knob worm 32b.

Description

Laser level

[0001] The present invention relates to a laser marking device having a light projecting unit that projects a marking line onto an object using a laser, and a rotating unit that rotates the light projecting unit horizontally.

[0002] Laser markers are known that project marking lines onto targets such as walls, ceilings, and floors at construction sites. Marking lines mainly include horizontal and vertical marks projected onto walls, ground marks projected onto floors, and ceiling marks projected onto ceilings. Some laser markers automatically rotate the light projecting unit using a motor to align the vertical marks with the desired position or to orient the horizontal marks in the desired direction if they are not projected 360 degrees. Other laser markers allow for fine adjustment of the light projecting unit rotation by manually operating a knob (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2006-215019

[0004] The laser marking device described in Patent Document 1 is provided with a separate drive mechanism driven by a motor and a drive mechanism driven by a knob, making it larger and heavier than types that do not have such mechanisms.

[0005] In addition, the laser marking device described in Patent Document 1 is equipped with a DC motor suitable for high-speed rotation during automatic rotation operation, and a stepping motor suitable for high-precision rotation, and each has a power transmission mechanism, making it large and heavy.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide a laser marking device that can be made compact.

[0007] In order to solve the above-mentioned problems and achieve the object, the laser marking device of the present invention is a laser marking device having a light-projecting unit that projects a laser marking line onto an object, and a rotating unit that supports the light-projecting unit and rotates it horizontally, wherein the rotating unit has a driven gear that rotates integrally with the light-projecting unit, a drive gear that drives the driven gear, a motor driven by a motor control unit, a knob that is rotated by hand, a planetary gear mechanism having a sun gear, a ring gear, a carrier and multiple pinion gears, a first drive wheel that is arranged coaxially with the sun gear over 360 degrees and rotates integrally with the sun gear, a second drive wheel with external teeth that is arranged over 360 degrees on the outer periphery of the ring gear, a motor worm arranged on the rotating shaft of the motor, and a knob worm arranged on the rotating shaft of the knob, wherein the first drive wheel meshes with the motor worm, and the second drive wheel meshes with the knob worm.

[0008] In the laser marking device according to the present invention, one planetary gear mechanism can be applied to two input portions, thereby making the device compact.

[0009] With the rotation center of the light projecting unit and the driven gear as a reference, the knob and knob worm may be located on the outer periphery side of the planetary gear mechanism, and the motor and motor worm may be located on the inner periphery side of the central axis of the planetary gear mechanism, with a portion overlapping the ring gear when viewed from the direction of the rotation center. This places the knob in a position that is easy to operate manually, and the motor is positioned inconspicuously and near the center, preventing imbalance in the center of gravity.

[0010] The motor and the motor worm may overlap the drive gear when viewed from the direction of the rotation center. The motor is disposed closer to the center.

[0011] The knob worm may be located closer to the light projecting portion than the motor worm, thereby enabling the motor and knob to be laid out in positions suitable for their respective functions in a balanced manner.

[0012] The carrier may be made up of a first member and a second member elastically biased relative to each other in the rotational direction by an elastic body, and an even number of the pinion gears may be provided, with one of two adjacent pinion gears journaled by the first member and the other journaled by the second member. This causes the two adjacent pinion gears to elastically attract or repel each other, thereby reducing backlash in a balanced manner with respect to the sun gear and the ring gear.

[0013] The drive gear may have a backlash suppression means for suppressing backlash between the drive gear and the driven gear. The backlash suppression means may be realized by configuring the driven gear as a scissors gear. Such a backlash suppression means provides favorable responsiveness.

[0014] The motor is a DC motor, and if a speed suppressing means is provided to apply rotational resistance to the rotating shaft of the motor, the rotation of the motor becomes stable.

[0015] The speed suppressing means may be an elastic body that directly or indirectly contacts the rotating shaft of the motor, thereby simplifying the configuration.

[0016] When the elastic body directly or indirectly abuts against the tip of the rotary shaft of the motor, the motor shaft is simply supported at both ends.

[0017] When the elastic body is indirectly brought into contact with the rotating shaft of the motor via a resin material, wear of the rotating shaft can be prevented.

[0018] The motor is a DC motor, and if a damper resistor is provided in the drive line, the rotation of the motor becomes stable.

[0019] Depending on the operating mode, the rotating unit may rotate the light projecting unit through an angle of 2 to 6 seconds to achieve high accuracy positioning.

[0020] The drive gear and the driven gear may be made of a resin material containing glass fiber. The gears constituting the planetary gear mechanism may be made of a resin material containing glass fiber. Such resin materials have a low linear expansion coefficient and are subject to little expansion and contraction due to temperature, which can prevent the vertical ink lines from moving over time.

[0021] An encoder is provided on the rotary shaft of the motor, and a signal from the encoder is supplied to the motor control unit, thereby improving the positioning accuracy of the vertical ink line.

[0022] In the laser marking device according to the present invention, one planetary gear mechanism can be applied to two input portions, thereby making the device compact.

[0023] FIG. 1 is a perspective view of a laser marker according to an embodiment. FIG. 2 is a schematic perspective view of a laser marker and a receiver that constitute a marker set. FIG. 3 is a perspective view of a rotating unit. FIG. 4 is a perspective view of the rotating unit with the housing removed, showing the drive mechanism and its surroundings from a diagonal downward angle. FIG. 5 is a perspective view of the rotating unit with the housing removed, showing the drive mechanism and its surroundings from a diagonal upward angle. FIG. 6 is a perspective view of the same portion as in FIG. 4, seen from the opposite side. FIG. 7 is an enlarged perspective view of the motor shaft and its surroundings from the inner diameter side. FIG. 8 is a bottom view of the drive mechanism and driven gear. FIG. 9 is a perspective view of the planetary gear mechanism as seen from a diagonal upward angle on the inner diameter side, with the center C0 as the reference. FIG. 10 is a perspective view of the planetary gear mechanism as seen from a diagonal downward angle on the outer diameter side, with the center C0 as the reference. FIG. 11 is an exploded perspective view of the planetary gear mechanism. FIG. 12 is an exploded perspective view of the driven gear and bearing. FIG. 13 shows a modified example of a backlash suppression means. Figure 14 shows a light receiver, where (a) is a front view and (b) is a top view based on the state of (a). Figure 15 is a block diagram of the marking set. Figure 16 is a general flowchart showing the processing of the automatic setting mode. Figure 17 is a general schematic diagram showing the positional relationship between the light receiving window and the vertical marking in the small angle rotation phase.

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser marking device according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiment.

[0025] Fig. 1 is a perspective view showing a laser marking device 10 according to an embodiment of the present invention. Fig. 2 is a schematic perspective view showing the laser marking device 10 and a light receiver 14 that constitute a marking device set 12.

[0026] The laser level 10 projects laser marking lines 16 onto objects such as walls, ceilings, and floors. While the marking lines 16 in Figure 2 are shown as dashed lines, they are actually projected as solid lines. Because the laser level 10 is used not only indoors but also outdoors during the day, the marking lines 16 are moderately bright. The marking lines 16 primarily include horizontal marks 16a and vertical marks 16b projected onto walls, a ground mark 16c projected onto the floor, and a ceiling mark 16d projected onto the ceiling. Two opposing vertical marks 16b, ground mark 16c, and ceiling mark 16d are connected to form a frame-shaped line 16e. Two of the frame-shaped lines 16e intersect at right angles to form a large rectangular line. The projection direction of the frame-shaped line 16e is adjustable by rotating the light-projecting unit 18, which will be described later. The horizontal marks 16a are projected 360 degrees around the object. The projection height of the horizontal marks 16a can be adjusted manually or automatically. The laser marking device 10 projects a lower point 16f directly below. The lower point 16f is point-like, unlike the other points, and serves as a reference point on the floor surface.

[0027] Depending on the model specifications and settings, some of these marking lines 16 may be omitted or the number of lines may vary. In the mode in which the frame-shaped line 16e automatically rotates, the laser marking device 10 and the receiver 14 work cooperatively. The length between the laser marking device 10 and the receiver 14 is defined as distance D. The applicable maximum value of distance D is, for example, approximately 15 m according to the specifications.

[0028] The laser marker 10 has a light projecting unit 18 that projects a laser marking line 16 onto an object, and a rotating unit 20 that supports the light projecting unit 18 from below and rotates it horizontally. The light projecting unit 18 is capable of endless rotation. Detachable legs 22 are provided below the rotating unit 20 at 120-degree intervals. The legs 22 have conical tips and are equipped with a length adjustment mechanism midway.

[0029] The light projecting unit 18 is generally cylindrical and includes an operation panel 18a at its top, four vertical exit windows 18b angled upward, multiple horizontal exit windows 18c around its periphery, a battery box 18d, and an external power port 18e. The operation panel 18a includes a mode selector switch, vertical line switch, horizontal line switch, and a battery level indicator. The vertical exit window 18b emits a frame-shaped line 16e. The horizontal exit window 18c emits a horizontal mark 16a. The laser level 10 operates on power supplied from a battery in the battery box 18d or the external power port 18e. A power switch is provided on the back of the light projecting unit 18, not shown in FIG. 1.

[0030] FIG. 3 is a perspective view of the rotating unit 20. As shown in FIGS. 1 and 3, the rotating unit 20 is based on a housing 24 having a disk portion 24a, a bulge portion 24b, a leg mounting portion 24c, and a lower cylinder 24d. The housing 24 is composed of two upper and lower members that are joined together to form an internal space. The disk portion 24a is a disk with a height-to-diameter ratio of, for example, approximately 1:4, and is coaxial with and has approximately the same diameter as the light projecting unit 18. The disk portion 24a is equipped with a bearing 26. The leg mounting portion 24c is where the leg 22 is attached. The lower cylinder 24d is a hollow cylinder through which the light projecting unit 18 projects the lower point 16f. A level 30 is provided on the side of the disk portion 24a. A control board 34 is provided inside the rotating unit 20. The control board 34 may be one or more circular or arc-shaped boards, and may be provided in a single layer or multiple layers.

[0031] The bulging portion 24b bulges outward from the side and downward of the disk portion 24a. The lateral bulging portion 24ba extends over a range of approximately 60 degrees from the center C0 of the disk portion 24a. The radial protrusion width of the lateral bulging portion 24ba from the center C0 is sufficiently smaller than that of the disk portion 24a, e.g., approximately one-third the radius of the disk portion 24a, which is the same as that of the battery box 18d. The drive mechanism 28 is housed within the bulging portion 24b. The bulging portion 24b is sufficiently small compared to the entire laser marker 10. In other words, the bulging portion 24b and the drive mechanism 28 therein have almost no effect on the overall size of the laser marker 10. The lower bulging portion 24bb of the bulging portion 24b is located in the space formed between the three legs 22, effectively utilizing the so-called dead space.

[0032] A knob 32, which can be rotated manually, protrudes from one circumferential end of the side bulge 24ba. The knob 32 is located on an extension of the tangent to the outer periphery of the disk portion 24a, with a gap large enough for one finger to fit between the knob 32 and the circumferential surface of the disk portion 24a. The knob 32 has an appropriate diameter and length to facilitate easy rotation. The knob 32 is located at an appropriate distance from the floor to facilitate easy rotation. Although the knob 32 is located outside the side bulge 24ba, it is also considered part of the drive mechanism 28. A driven gear 36 is provided inside the rotating unit 20, coaxial with the bearing 26 and rotating integrally therewith. The driven gear 36 has a diameter, for example, approximately two-thirds that of the disk portion 24a, and is driven by the drive mechanism 28. The knob 32 is used to manually rotate the light-projecting unit 18, and is light in weight and has a large reduction ratio set by the reducer 50 described below, so it can be operated accurately with light force.

[0033] The light projecting unit 18 is held down against the bearing 26 by a predetermined holding plate, and rotates integrally with the bearing 26 and the driven gear 36. The light projecting unit 18 can be rotated while sliding against the bearing 26 by direct manual operation by the user, and can also be rotated by the knob 32 and motor 42 via the reducer 50.

[0034] Figure 4 is a perspective view of the drive mechanism 28 and its surroundings in the rotating unit 20 with the housing 24 removed, viewed obliquely from below. Figure 5 is a perspective view of the drive mechanism 28 and its surroundings in the rotating unit 20 with the housing 24 removed, viewed obliquely from above. Figure 6 is a perspective view of the same area as in Figure 4, viewed from the opposite side. Figure 7 is an enlarged perspective view of the motor shaft 42b and its surroundings, viewed from the inner diameter side. In describing the drive mechanism 28, the side closer to the center C0 is referred to as the inner diameter side, and the side farther from it is referred to as the outer diameter side. Furthermore, the radial direction and circumferential direction are defined based on the center C0.

[0035] As shown in Figures 4 and 5, the drive mechanism 28 is configured with a cage 38 as its base. The cage 38 is a frame-shaped cage that opens in the radial direction and includes a mounting plate 38a fixed to the housing 24, two support posts 38b extending downward from the mounting plate 38a, a gear guard 38c that protrudes above the mounting plate 38a, and a bottom cover plate 38d. The mounting plate 38a, support posts 38b, and gear guard 38c are integrally configured, and the bottom cover plate 38d is fixed to the two support posts 38b with screws. The gear guard 38c is a small, low, cylindrical cage with a bottom that is open on its inner diameter side.

[0036] The mounting plate 38a has an arcuate portion 38aa that fits along the outer periphery of the driven gear 36, and a bracket fixing portion 38ab that protrudes radially outward from the arcuate portion 38aa. Both ends of the arcuate portion 38aa are screwed to the housing 24, and a support post 38b is erected nearby. The arcuate portion 38aa is within the range of the disk portion 24a (see FIG. 8) of the housing 24, and the bracket fixing portion 38ab fits into a side bulge portion 24ba (see FIG. 8).

[0037] A knob support bracket 40 is fixed to the underside of the bracket fixing portion 38ab. The knob support bracket 40 is slightly long in the circumferential direction and has a U-shape with downward bent pieces 40a at both ends. The bent pieces 40a are moderately low, for example, about half the height of the support posts 38b. Axial holes are formed in the two bent pieces 40a to support the knob shaft 32a. The knob shaft 32a rotates integrally with the knob 32, but the knob 32 is detachable from the knob shaft 32a. A knob worm 32b is provided between the two bent pieces 40a on the knob shaft 32a. In each figure, the knob worm 32b, a motor worm 42c (described later), and a first drive wheel 54 are shown with their teeth omitted. The grooves of the knob worm 32b and the motor worm 42c are of a single or double groove configuration, which has a self-locking effect, so that the worm side cannot be driven from the wheel side.

[0038] 6 and 7, one end of the lower cover plate 38d on the inner diameter side (the right side in FIG. 6) is bent downward to form a motor fixing piece 38da. The motor fixing piece 38da forms a surface that follows the vertical and radial directions and has a height, for example, about half that of the support column 38b. A spring hole 38db that is slightly elongated in the radial direction is formed in the lower cover plate 38d at a position slightly circumferentially away from the motor fixing piece 38da.

[0039] The end face of a substantially cylindrical main body 42a of the motor 42 is fixed to the motor fixing piece 38da with a screw. The motor 42 is, for example, a small DC motor. The end face of the main body 42a and the motor fixing piece 38da have the same shape. The motor shaft 42b of the motor 42 protrudes from the end face of the main body 42a through a hole in the motor fixing piece 38da. The main body 42a and the motor shaft 42b are aligned in a substantially circumferential direction. The tip 42ba of the motor shaft 42b is hemispherical and protrudes to a position above the spring hole 38db. A motor worm 42c is provided on the motor shaft 42b.

[0040] A sensor box 44 is provided on the side of the motor 42 opposite the side from which the motor shaft 42b protrudes. The width of the sensor box 44 along the motor shaft 42b is approximately half that of the main body 42a. The cross section perpendicular to the motor shaft 42b is rectangular and slightly larger than the main body 42a, giving the sensor box an overall flat shape. The sensor box 44 houses a rotary encoder 44a and the drive lines of the motor 42. The rotary encoder 44a is a circular plate with slits attached to the motor shaft 42b. It transmits or reflects infrared light to output a pulse signal corresponding to the rotation speed and angle of the motor 42. The slits of the rotary encoder 44a have phases A and B that are out of phase with each other, and the rotation angle and direction can be detected by optically reading each phase. The rotary encoder 44a is used to control the rotation angle of the light projector 18, but it can also be used to adjust the rotation speed before product shipment.

[0041] The laser marking device 10 has an automatic setting mode in which the positioning of the vertical marking 16b is performed by automatically rotating the light projecting unit 18 under the action of the motor 42. The resolution of the slit of the rotary encoder 44a is set based on the maximum applicable distance between the laser marking device 10 and the light receiver 14 in this mode, the characteristics of the laser optical system, the required positioning accuracy, the reduction ratio of the reducer 50, etc.

[0042] A metal leaf spring (elastic body) 46 is attached to the lower cover plate 38d. The leaf spring 46 is L-shaped and includes a relatively wide fixed piece 46a and a relatively narrow shaft contact piece 46b. The fixed piece 46a is fixed to the underside of the lower cover plate 38d, and the shaft contact piece 46b protrudes upward through the spring hole 38db. The shaft contact piece 46b is slightly wider than the tip 42ba of the motor shaft 42b and elastically presses against the tip 42ba, thereby urging the motor shaft 42b toward the main body 42a. In other words, the shaft contact piece 46b functions as a speed suppression means that applies rotational resistance to the motor shaft 42b.

[0043] The shaft abutment piece 46b abuts against the tip 42ba, thereby simply supporting the motor shaft 42b at both ends and reducing axial runout. However, depending on the conditions, it may also abut a portion other than the tip 42ba. The speed suppression means for the motor shaft 42b is not limited to the leaf spring 46, and may be, for example, a coil spring. The shaft abutment piece 46b indirectly abuts against the tip 42ba via a small, thin resin piece 48. The resin piece 48 is, for example, a nylon piece and is adhesively fixed to the shaft abutment piece 46b. The presence of the resin piece 48 prevents wear of the shaft abutment piece 46b and the tip 42ba. Furthermore, the tip 42ba abuts against the resin piece 48 while slightly recessing it, further reducing axial runout. However, depending on the conditions, the resin piece 48 may be omitted and the shaft abutment piece 46b and the tip 42ba may abut directly. The tip 42ba is semispherical, and the contact portion with the resin piece 48 or the shaft contact piece 46b is microscopically circular, making it suitable for rotation.

[0044] As shown in FIGS. 4 to 6 , the drive mechanism 28 includes a speed reducer 50. The speed reducer 50 is based on a central shaft 52. A first drive wheel 54 is fitted to the lower part of the central shaft 52, a drive gear 56 is fitted to the upper part, and a planetary gear mechanism 58 is provided between them. Two opposing D-shaped cutouts 52a (see FIG. 10 ) are formed in the lower part of the central shaft 52. The first drive wheel 54 has a flat portion whose central hole matches the two D-shaped cutouts 52a, allowing it to rotate integrally with the central shaft 52. The first drive wheel 54 serves as a first input part and meshes with the motor worm 42c. A coil spring 55a and a pair of upper and lower discs 55b (see also FIG. 10 ) vertically bias the first drive wheel 54 and the planetary gear mechanism 58. A second drive wheel 60, whose external teeth are on a ring gear 66 that forms the outer shell of the planetary gear mechanism 58, serves as a second input part and meshes with the knob worm 32b. The drive gear 56 is integral with a part of a carrier 70 (described later) and serves as an output part that meshes with the driven gear 36 .

[0045] The planetary gear mechanism 58 is provided between the two support posts 38b. The lower end of the central shaft 52 is fitted into and supported by a shaft hole formed in the lower cover plate 38d, and the upper end is fitted into and supported by a shaft hole formed in the gear guard 38c.

[0046] The planetary gear mechanism 58 has two input sections, the first drive wheel 54 and the second drive wheel 60, but the motor 42 and knob 32 that provide input to these have different layout requirements. In other words, the motor 42 needs to be housed compactly in an inconspicuous location inside the housing 24, while the knob 32 needs to be located in a location outside the housing 24 that is reasonably visible and easy to operate. The laser level 10 meets these requirements as follows.

[0047] The knob worm 32b, which meshes with the second drive wheel 60 at an intermediate height in the reducer 50, is located relatively higher than the motor worm 42c, which meshes with the lower first drive wheel 54, i.e., closer to the light projector 18. Accordingly, the knob 32 is located higher than the motor 42. Therefore, the knob 32 is located relatively high, ensuring a sufficient distance from the floor for easy operation. The motor 42 is located relatively low, making it easy to place below the disk 24a. The motor 42 is heavier than the knob 32, and by storing it in the lower bulge 24bb, the center of gravity of the entire laser marker 10 is lowered and stabilized. Furthermore, the relatively heavy motor 42 is located at least within the range of the disk 24a (see FIG. 8), preventing the center of gravity of the entire laser marker 10 from becoming extremely unbalanced.

[0048] Figure 8 is a bottom view of the drive mechanism 28 and the driven gear 36. In Figure 8, the bottom cover plate 38d and the leaf spring 46 are omitted, and the housing 24 is shown in phantom lines. The first drive wheel 54 has a smaller diameter than the second drive wheel 60, for example, about 2 / 5 the diameter.

[0049] With respect to the center C0, the motor worm 42c meshes with the first drive wheel 54 on the inner diameter side, and is contained within the range of the disk portion 24a when the motor 42 and sensor box 44 are viewed from the bottom side (viewed from the direction of the rotation center). Furthermore, because the first drive wheel 54 has a relatively small diameter, the motor worm 42c that meshes with it is not positioned excessively toward the inner diameter side, and in this embodiment, is generally located at approximately the same position as the outer periphery of the driven gear 36. The motor shaft 42b, main body 42a, and sensor box 44 are arranged generally along the circumferential direction and do not extend too far into the inner diameter side. Therefore, the downward bulge portion 24bb (see FIG. 3) that houses the motor 42, sensor box 44, and first drive wheel 54 is compact, eliminating wasted space inside the housing.

[0050] With the center C0 as the reference, the knob worm 32b meshes with the outer diameter side of the second drive wheel 60. The second drive wheel 60 has a relatively large diameter and protrudes slightly beyond the range of the disk portion 24a, and as the motor worm 42c meshes with this portion, the knob 32 protrudes in the tangential direction, and is positioned for good operability.

[0051] In this way, by displacing the motor worm 42c and the knob worm 32b vertically and radially, it is possible to lay out the motor 42 and the knob 32 in positions that are optimal for their respective functions in a balanced manner.

[0052] Next, the planetary gear mechanism 58 will be described. Fig. 9 is a perspective view of the planetary gear mechanism 58 as seen from diagonally above the inner diameter side with the center C0 as the reference. Fig. 10 is a perspective view of the planetary gear mechanism 58 as seen from diagonally below the outer diameter side with the center C0 as the reference. Fig. 11 is an exploded perspective view of the planetary gear mechanism 58. The ring gear 66 is omitted from Fig. 11. In the description of the planetary gear mechanism 58, the side closer to the center C1 of the central shaft 52 is referred to as the inner diameter side, and the side farther from it is referred to as the outer diameter side.

[0053] 9 and 10, the planetary gear mechanism 58 is configured with the central axis 52 as the reference, and includes a sun gear 64, a ring gear 66, four pinion gears 68, and a carrier 70. The sun gear 64, ring gear 66, and pinion gears 68 have the same tooth width and are aligned vertically. The sun gear 64, ring gear 66, and pinion gears 68 are spur gears, but they may also be helical gears or the like.

[0054] The sun gear 64 is relatively small and is integral with the central shaft 52 at approximately its center. The underside of the sun gear 64 is positioned in contact with the flange 52b. The ring gear 66 has internal teeth and is integral with the second drive wheel 60, which has external teeth. Hereinafter, the term "ring gear 66" will refer to the internally toothed portion. The ring gear 66 is relatively large and, together with the second drive wheel 60, forms the outer shell of the planetary gear mechanism 58. The underside of the ring gear 66 is covered by a cover 66b (see FIG. 4). Four pinion gears 68 are disposed at equal 90-degree angles between the sun gear 64 and the ring gear 66, and each pinion gear 68 meshes with the sun gear 64 and the ring gear 66. The number of pinion gears 68 may be two, three, five, or more.

[0055] The second drive wheel 60 is capable of moving up and down relative to the central shaft 52 and is free to move up and down, but strictly speaking, the sun gear 64 acts as a stopper in the upward direction, so it is only free to move downward. When the knob worm 32b rotates at this time, the second drive wheel 60 moves up and down at the same time, so pressure is applied by the coil spring 55a to hold it down. This eliminates loss of rotation transmission from the knob 32 to the light-projecting unit 18.

[0056] As shown in Figures 10 and 11, the carrier 70 is composed of a first member 72 and a second member 74. The first member 72 is disk-shaped, with the drive gear 56 integrally formed on its upper surface protruding. The underside of the first member 72 has a recess 72a extending radially across the lower surface, four approximately triangular prism-shaped support members 72b protruding upward at locations other than the recess 72a, and a fitting tube 72d protruding downward around a central hole 72c. The support members 72b are provided at positions that separate the four pinion gears 68. The central shaft 52 is inserted through the central hole 72c. The peripheral edge of the first member 72 fits into an annular step 66a (see Figure 9) on the upper surface of the ring gear 66 to rotatably support the ring gear 66.

[0057] The recess 72a has an arcuate portion 72aa that is concentric with the fitting cylinder 72d, grooves 72ab formed in the circumferential direction near both ends, and spring seat recesses 72ac formed on the clockwise surface of both ends in Figure 11. A spring 76 is inserted into the groove 72ab.

[0058] The second member 74 has a shape that fits into the recess 72a and has a central annular portion 74a and rotating pieces 74b that protrude on both radial sides. The second member 74 can rotate slightly within the width of the recess 72a around the center C1 by fitting the annular portion 74a into the fitting cylinder 72d.

[0059] Each of the two pivot pieces 74b has a protrusion 74ba formed on the clockwise surface at its end in FIG. 11, a circumferential groove 74bb formed on the upper surface of the end, and a spring seat piece 74bc protruding downward from the counterclockwise end of the groove 74bb. In FIG. 11, a portion of the groove 74bb and the spring seat piece 74bc is shown in cross section for ease of understanding. The protrusion 74ba fits into the groove 72ab. The groove 74bb, together with the groove 72ab, forms a storage space for the spring 76.

[0060] Four pinion shafts 70a protrude from the lower surface of the carrier 70. Each pinion shaft 70a is provided in a position to support a pinion gear 68. Two of the four pinion shafts 70a are located in opposing positions across the fitting cylinder 72d of the first member 72, and the remaining two are located in opposing positions across the annular portion 74a of the second member 74.

[0061] The four pinion gears 68 are disposed at equal angles (90 degrees in this case) relative to the sun gear 64 and the ring gear 66. Therefore, the line connecting the two pinion shafts 70a facing each other across the fitting tube 72d is perpendicular to the line connecting the two pinion shafts 70a facing each other across the annular portion 74a. When the first member 72 and the second member 74 are positioned in this relative manner, the two springs 76 are elastically compressed by the walls of the spring seat recesses 72ac and the spring seat pieces 74bc. This elastically biases the first member 72 and the second member 74 relative to each other in the rotational direction. In the example shown in FIG. 11 , the first member 72 is biased clockwise, and the second member 74 is biased counterclockwise.

[0062] As described above, the planetary gear mechanism 58 is a two-input, one-output type, with the first drive wheel 54 as the first input portion, the second drive wheel 60 as the second input portion, and the drive gear 56 as the output portion. The first drive wheel 54 of the first input portion forms a worm wheel mechanism together with the motor worm 42c and rotates as the motor worm 42c rotates, but conversely, even if rotational torque is applied to the first drive wheel 54, the motor worm 42c does not rotate due to a self-locking effect. The second drive wheel 60 of the second input portion forms a worm wheel mechanism together with the knob worm 32b and rotates as the knob worm 32b rotates, but conversely, even if rotational torque is applied to the second drive wheel 60, the knob worm 32b does not rotate due to a self-locking effect.

[0063] When the motor 42 rotates the motor worm 42c, the first drive wheel 54, the central shaft 52, and the sun gear 64, the second drive wheel 60 is fixed by a self-locking action. Therefore, the pinion gear 68 rotates about the pinion shaft 70a and revolves around the center C1 depending on the rotation state of the sun gear 64 and the fixed state of the ring gear 66.

[0064] When the knob worm 32b and the second drive wheel 60 rotate under the action of the knob 32, the first drive wheel 54 is fixed by a self-locking action. Therefore, the pinion gear 68 rotates about the pinion shaft 70a and revolves about the center C1 depending on the fixed state of the sun gear 64 and the rotating state of the ring gear 66.

[0065] Therefore, as the pinion gear 68 revolves, the carrier 70 and the drive gear 56 rotate at a reduced speed, thereby driving the driven gear 36 .

[0066] Such a planetary gear mechanism 58 can be applied to two input sections with one mechanism, allowing for miniaturization, and the two input sections do not interfere with each other's operation. The self-locking mechanism does not have a special brake, and the self-locking section does not create load resistance when viewed from one input side, reducing power consumption on the motor 42 side and providing light and easy operability on the knob 32 side. Of the two input sections, the first drive wheel 54, which is the first input section, is coaxially arranged with the drive gear 56, which is the output section, simplifying layout. The planetary gear mechanism 58 is capable of endless rotation.

[0067] In addition, when roughly aligning the position of the light projecting unit 18, the laser marking device 10 of this embodiment can be rotated by hand so that it slides relative to the bearing 26, but this rotation does not involve the gears of the reducer 50. If the light projecting unit 18 were fixed to the bearing 26 to prevent it from sliding, a non-self-locking configuration (such as a three-row configuration of the grooves in the knob worm 32b) could be adopted to create a mechanism that uses the reducer 50.

[0068] Furthermore, there is an even number of pinion gears 68 (four in this embodiment), and the pinion shafts 70a of adjacent pinion gears 68 are provided as separate first and second members 72 and 74 that are elastically biased relative to each other in the rotational direction by springs 76. Therefore, two adjacent pinion gears 68 elastically attract or repel each other, thereby reducing backlash in a balanced manner with respect to the sun gear 64 and ring gear 66, and achieving favorable responsiveness.

[0069] 12 is an exploded perspective view of the driven gear 36 and the bearing 26. The driven gear 36 is a scissors gear (backlash suppression means) that is configured by combining a first gear 78 and a second gear 80. In FIG. 12, the first gear 78 is illustrated upside down relative to the second gear 80 and the bearing 26.

[0070] The first gear 78 has an annular fitting tube 78a that protrudes upward from its inner periphery, fixed portions 78b spaced 90 degrees apart around the fitting tube 78a, and two circumferential grooves 78c on its top surface. The first gear 78 fits into the lower part of the bearing 26 and is fixed by the fixed portions 78b. The vertical width of the fitting tube 78a is approximately the same as the tooth width of the second gear 80, and the top surface of the fitting tube 78a abuts against a portion of the bearing 26 to secure space for the second gear 80. Two grooves 78c are formed on the top surface at opposing positions, each located midway between the two fixed portions 78b. A small spring seat 78ca protrudes upward from one end of the groove 78c. A spring 82 is inserted into the groove 78c.

[0071] The underside of the second gear 80 has two grooves 80b formed in the circumferential direction. The two grooves 80b are formed in opposing positions, at positions that roughly correspond to the grooves 78c of the first gear 78. A small spring seat 80ba protrudes downward from one end of the grooves 80b. The grooves 80b, together with the grooves 78c, form a space for accommodating the spring 82.

[0072] The first gear 78 and the second gear 80 have the same module and number of teeth, but when they are combined vertically, the two springs 82 are elastically compressed by the spring seats 78ca and 80ba, respectively. This elastically biases the first gear 78 and the second gear 80 relative to each other in the rotational direction. When the driven gear 36 is engaged with the drive gear 56, the teeth of the lower first gear 78 and the teeth of the upper second gear 80 elastically spread apart in the circumferential direction, resulting in tight contact with the adjacent teeth on both sides of the drive gear 56, reducing backlash and achieving favorable responsiveness. However, depending on design conditions, the driven gear 36 may be configured as a simple single gear rather than a scissors gear.

[0073] 13 is a diagram showing a modified example of the backlash suppression means. As the backlash suppression means between the driven gear 36 and the drive gear 56, other than using the driven gear 36 as a scissors gear, for example, the means shown in FIG. 13 can be applied.

[0074] The backlash suppression means 84 according to this modification includes a small pulley 84a that rotates coaxially with the drive gear 56, a large pulley 84b that rotates coaxially with the driven gear 36, a belt 84c stretched between them, and a tension pulley 84d that presses the belt 84c from the side. The belt 84c is a V-belt, a flat belt, or the like. The belt 84c is tensioned by being pressed from the side by the tension pulley 84d, and the reducer 50 including the drive gear 56 is elastically biased in the radial direction, thereby reducing backlash between the drive gear 56 and the driven gear 36. The backlash suppression means 84 can also be used for both speed reduction and transmission of driving force, in which case the drive gear 56 and the driven gear 36 may be omitted.

[0075] Each gear (including the worm wheel mechanism) constituting the reducer 50, including the planetary gear mechanism 58, is made of a resin material (e.g., polyacetal) containing glass fiber. Such resin materials have a low linear expansion coefficient and minimal temperature-related expansion and contraction, thereby preventing the vertical mark 16b from shifting over time. Furthermore, the driven gear 36 and the driven gear 36 are the final stage driving the light-emitting unit 18. Furthermore, the driven gear 36 is larger in volume than the other gears and rotates integrally with the light-emitting unit 18. Therefore, using a resin material containing glass fiber effectively prevents the vertical mark 16b from shifting due to temperature changes. Furthermore, the prevention of vertical mark 16b shift is particularly effective when the vertical mark 16b is positioned with high precision and during long-term use. Furthermore, using resin gears offers advantages such as lighter weight, lower cost, and better moldability than metal gears.

[0076] Next, we will explain the configuration and operation of the marking set 12. The marking set 12 is made up of the laser marking device 10 and the light receiver 14. The mechanical configuration of the laser marking device 10 is as described above.

[0077] Figure 14 shows the light receiver 14, with (a) being a front view and (b) being a top view based on the state in (a). Figure 14(a) shows the light receiver 14 placed horizontally on the floor G, and the following explanation will be based on the horizontal placement state in Figure 14(a) in terms of up / down and left / right. The light receiver 14 has a slightly long rectangular shape when viewed from the front, and is large enough to be operated with one hand. The light receiver 14 has a transmission function for the laser marking device 10, and can be operated as a remote control.

[0078] The light receiver 14 has a rectangular light receiving window 86 near one end and a plate 88 near the other end. The plate 88 is for fixing to a predetermined holder (not shown). A right proximity LED 90a, a left proximity LED 90b, and a coincidence LED 90c are provided above the light receiving window 86. The light receiving window 86 is divided into two parts, a right sensor (light receiving element) 92a and a left sensor (light receiving element) 92b, and each sensor is, for example, a photo sensor, and has a certain width in the left-right direction in FIG. 14(a). The boundary between the right sensor 92a and the left sensor 92b is a marking target line 92c, which is the target position for the vertical mark 16b.

[0079] Between the light receiving window 86 and the plate 88 are provided a power switch 14a, a line switch 14b, a connection indicator LED 14c, a brightness switch 14d, a volume switch 14e, a mode switch 14f, and other switches. The power switch 14a turns the power to the receiver 14 on and off. The line switch 14b projects and stops the marking line 16. The brightness switch 14d adjusts the brightness of the marking line 16. Pressing the power switch 14a while holding down the line switch 14b and the brightness switch 14d establishes wireless communication between the receiver 14 and the laser level 10, and the connection indicator LED 14c lights up. The volume switch 14e adjusts the volume of the buzzer and other sounds. The mode switch 14f selects between two modes for rotating the light projector 18 of the laser level 10. The modes for rotating the light projector 18 include an automatic setting mode and an endless rotation mode.

[0080] When the automatic setting mode is applied, the receiver 14 is placed horizontally so that the marking target line 92c is aligned with the target position of the vertical mark 16b (see also Figure 2). The receiver 14 may be oriented left to right inversely to that shown in Figure 14(a). When the endless rotation mode is applied, it is recommended to hold the receiver 14 by hand and operate it.

[0081] A forward rotation switch 14g and a reverse rotation switch 14h are provided on the top surface (FIG. 14(b)) and bottom surface, respectively, of the light receiver 14. In the endless rotation mode, pressing the forward rotation switch 14g or the reverse rotation switch 14h rotates the light projector 18 in the forward or reverse direction, and pressing the forward rotation switch 14g or the reverse rotation switch 14h again stops the light projector 18.

[0082] FIG. 15 is a block diagram of the laser marking set 12. The receiver board 94a inside the receiver 14 is equipped with a receiver computer 94b, two input interfaces 94c and 94d, and a transmission module (transmitter) 94e. The input interfaces 94c and 94d convert signals from the right sensor 92a and the left sensor 92b and provide the converted signals to the receiver computer 94b. Based on the signals provided via the input interfaces 94c and 94d, the receiver computer 94b can determine whether the vertical marking 16b (shown in phantom lines) is irradiated by either the right sensor 92a or the left sensor 92b, or whether it is irradiated by either sensor. The receiver computer 94b performs a determination process based on these signals and transmits a signal to the laser marking device 10 via the transmission module 94e. The transmission module 94e transmits wireless signals to the laser marking device 10 in accordance with a predetermined standard, such as Bluetooth (registered trademark). Communication between the light receiver 14 and the laser marking device 10 is basically one-way.

[0083] The receiver 14 is provided with an accelerometer 94f, which enables the receiver computer 94b to recognize whether the receiver 14 is placed horizontally or vertically. Although not shown, switches, lamps, buzzers, etc. are connected to the receiver computer 94b so that input and output can be performed by the receiver computer 94b. Some or all of the right sensor 92a, left sensor 92b, accelerometer 94f, switches, lamps, buzzers, etc. may be mounted on the receiver board 94a.

[0084] The light projecting unit 18 of the laser marking device 10 is provided with a light projecting unit board 96a and a wireless transmission board 96b. A light projecting unit computer 96c, a receiving module 96d, and a laser emitting unit 96e are mounted on the light projecting unit board 96a. The receiving module 96d receives wireless data from the transmitting module 94e and supplies it to the light projecting unit computer 96c. The light projecting unit computer 96c is connected to the operation panel 18a (see FIG. 1) and drives the laser emitting unit 96e to project and stop the marking line 16 based on signals supplied from the transmitting module 94e and operations on the operation panel 18a. The light projecting unit computer 96c also transmits predetermined signals to the rotation unit 20 via the wireless transmission board 96b.

[0085] An infrared light emitting unit 96f is mounted on the wireless transmitting board 96b, and transmits a signal received from the light projecting unit computer 96c to the rotating unit 20 using infrared light. This transmission format is, for example, near-infrared pulse position modulation.

[0086] The rotating unit 20 has a rotating unit computer 98a and a photodiode 98b mounted on the control board 34. The rotating unit 20 also has a driver 98c and a damper resistor 98d. The photodiode 98b converts an optical signal obtained from the infrared light emitter 96f into an electrical signal and supplies it to the rotating unit computer 98a. The rotating unit computer 98a drives the driver 98c to rotate the motor 42 based on signals provided from the light receiver computer 94b and the light emitter computer 96c via the infrared light emitter 96f and a signal obtained from the rotary encoder 44a. The driver 98c converts the rotation / stop signal into a power signal that rotates the motor 42 and also has a safety function that stops the motor 42 if an abnormality occurs. By continuing to supply power, the motor 42 continuously rotates at a rotational speed where the rotation load and current are balanced.

[0087] A damper resistor 98d is inserted into each of the two drive lines between the driver 98c and the motor 42, and the initial rotation, which consumes the most power, is started with a gradual acceleration by utilizing the voltage drop caused by the resistor. Although it is possible to combine the damper resistors 98c into one, dividing them into two reduces the amount of heat generated per resistor and improves thermal balance. The driver 98c and damper resistor 98d may be provided in the sensor box 44 or the control board 34.

[0088] Next, the automatic setting mode processing by the laser marking set 12 will be described. The automatic setting mode is a mode in which the vertical marking 16b is automatically aligned with the marking target line 92c between the right sensor 92a and the left sensor 92b. Prior to this processing, the automatic setting mode is selected in advance using the mode switch 14f, and the receiver 14 is placed horizontally on the floor G so that the marking target line 92c is the target position of the vertical marking 16b. It is also assumed that the light projecting unit 18 is projecting at least one vertical marking 16b. When manually adjusting the position of the vertical marking 16b using the knob 32, the user may have to go back and forth between the wall and the laser marking set 10 multiple times to confirm the irradiation position of the vertical marking 16b. However, in the automatic setting mode, the laser marking set 10 and the receiver 14 work together to set the vertical marking 16b to the target position, eliminating the need for or reducing the number of round trips.

[0089] Figure 16 is a schematic flowchart showing the processing in the automatic setting mode. Steps S101 to S108 on the left side of Figure 16 are processing performed by the receiver computer 94b on the receiver 14 side, and steps S201 to S204 on the right side are processing performed by the rotation unit computer 98a on the laser marking device 10 side. The dashed arrows in Figure 16 indicate signals transmitted from the receiver computer 94b to the rotation unit computer 98a, and these signals are relayed by the light-projection unit computer 96c inside the laser marking device 10.

[0090] 17 is a schematic diagram showing the positional relationship between the light receiving window 86 and the vertical ink 16b in the minute angle rotation phase. In FIG. 17, the direction from right to left is the normal rotation, and the opposite direction is the reverse rotation.

[0091] The automatic setting mode is divided into a first wide-angle rotation phase corresponding to steps S102 to S104, and a second small-angle rotation phase corresponding to steps S105 to S107. However, these names are used to make it easier to understand, and the rotation angle in the wide-angle rotation phase may be small.

[0092] In step S101, the user presses the forward rotation switch 14g or the reverse rotation switch 14h of the photoreceiver 14, thereby starting the automatic setting mode.

[0093] In step S102, a motor rotation command is wirelessly transmitted to the laser marking device 10. This transmitted signal includes a command to start rotation of the motor 42 and the rotation direction. The rotation direction is determined by whether the forward rotation switch 14g or the reverse rotation switch 14h is pressed.

[0094] In step S201, the motor 42 of the laser marking device 10 is driven to rotate in the instructed direction, whereby the vertical marking 16b irradiated by the light projecting unit 18 starts to move.

[0095] If either the right sensor 92a or the left sensor 92b on the receiver 14 side detects the vertical mark 16b (Yes) through the processing of step S103, the process proceeds to step S104; if not (No), the process waits for light reception. If there are multiple vertical mark 16b, the process proceeds to step S104 when the first one is detected. In the receiver 14, when the right sensor 92a detects the vertical mark 16b, the right proximity LED 90a is turned on, and when the left sensor 92b detects the vertical mark 16b, the left proximity LED 90a is turned on.

[0096] In step S104, the light receiver 14 wirelessly transmits a motor pause command to the laser marking device 10, and the laser marking device 10 temporarily stops the motor 42 and the light projector 18 based on the wireless reception (S202). Because the light projector 18 rotates relatively quickly during the wide-angle rotation phase, if the distance D (see FIG. 2) is long, the vertical marking 16b moves at a relatively high speed. Furthermore, the light projector 18 has inertia, making it impossible to perform highly accurate angle control even if the laser marking device 10 transitions to the minute-angle rotation phase. Therefore, in this embodiment, when either the right sensor 92a or the left sensor 92b first detects the vertical marking 16b, a pause signal is transmitted to temporarily stop the motor 42 prior to transitioning to the minute-angle rotation phase.

[0097] The micro-angle rotation phase begins in step S105. In the micro-angle rotation phase, after either the right sensor 92a or the left sensor 92b first detects the vertical marking 16b, the laser marking device 10 controls the motor 42 to rotate forward or reverse based on the transmission signal received from the light receiver 14, so that the rotary encoder 44a outputs a predetermined number of pulses based on the judgment and repetition process of step S106, until the vertical marking 16b is positioned on the marking target line 92c. The number of pulses is preset and is initially a relatively large number, and is decreased each time the vertical marking 16b passes the marking target line 92c, causing the rotation of the motor 42 to reverse. However, the specified number of pulses must of course be 1 or greater, i.e., not 0.

[0098] Specifically, in step S105, a motor micro-rotation command is wirelessly transmitted to the laser marking device 10. This transmitted signal includes an instruction for the direction of rotation of the motor 42 and a pulse count corresponding to the rotational displacement angle. The direction of rotation is forward when the right sensor 92a detects the vertical marking 16b, and reverse when the left sensor 92b detects the vertical marking 16b. In the example shown in FIG. 17, the initial pulse count is 10, and is subsequently set to decrease to 4, 3, and 2 each time the vertical marking 16b crosses the marking target line 92c. The rectangular waveform at the bottom of FIG. 17 is a schematic representation of the pulses output by the rotary encoder 44a. However, the relative width between the pulse and the light-receiving window 86 may vary depending on the distance D and the angle of the light-receiving device 14.

[0099] This will be explained further with reference to Figure 17. Assume that in the initial stage of the small angle rotation phase, the vertical mark 16b is located on line L1 at the right corner of the right sensor 92a. The position of this line L1 can change depending on factors such as distance D. If distance D is long, the vertical mark 16b rotating forward may overrun and go beyond the marking target line 92c, but because the right sensor 92a and left sensor 92b have an appropriate width, it will not go beyond the left end of the left sensor 92b.

[0100] In step S203, the laser marking device 10 rotates the motor 42 in the forward direction based on the signal sent in step S105 until the rotary encoder 44a outputs 10 pulses. Line L1 is displaced in the forward direction by 10 pulses to become line L2. Note that this number of pulses may be counted based on either phase A or phase B, and different reference phases may be used for forward and reverse rotation.

[0101] In step S106 (marking coincidence determination), the light receiver 14 determines whether the vertical marking 16b coincides with the marking target line 92c, and if they coincide, proceed to step S107 (Yes), otherwise return to step S105. This determination is made if neither the right sensor 92a nor the left sensor 92b detects the vertical marking 16b or if the received light intensity is sufficiently small.

[0102] Because L2 is detected by the right sensor 92a, the receiver 14 issues a command to the laser marking device 10 to rotate forward by another 10 pulses. When the vertical marking device 16b moves in the forward direction by 10 pulses, it moves to line L3. Because L3 is detected by the left sensor 92b, it has passed the marking target line 92c, and the receiver 14 issues a command to rotate backward by four pulses. When the vertical marking device 16b moves in the reverse direction by four pulses, it moves to line L4. Because L4 is detected by the left sensor 92b, the receiver 14 issues a command to the laser marking device 10 to rotate backward by another four pulses. When the vertical marking device 16b moves in the reverse direction by four pulses, it moves to line L5. Because L5 is detected by the right sensor 92a, it has passed the marking target line 92c, and the receiver 14 issues a command to rotate forward by three pulses. When the vertical marking device 16b moves in the forward direction by three pulses, it moves to line L6. Since L6 is detected by the left sensor 92b, it has passed the marking target line 92c, and an instruction to reverse by two pulses is issued from the light receiver 14. When the vertical mark 16b is displaced in the reverse direction by two pulses, it moves to line L7.

[0103] Since the line L7 coincides with the range of the marking target line 92c, the determination in step S106 becomes "Yes", and the process proceeds to step S107. In the light receiver 14, the coincidence LED 90c is turned on.

[0104] In step S107, the same judgment process as in step S106 is performed. If the vertical marking 16b coincides with the marking target line 92c for a predetermined number of times (or for a predetermined period of time) or more, the process proceeds to step S108, but if the condition is not met for less than N times, the process returns to step S106. The vertical marking 16b is displaced based on the rotation of the rotating unit 20, but is adjusted independently by the light projecting unit 18 to ensure perpendicularity. Therefore, the position of the vertical marking 16b may not be determined by the rotating unit 20 alone, and the standby process in step S107 allows the vertical marking 16b to stably coincide with the marking target line 92c.

[0105] In step S108, the automatic setting mode is ended and this is notified to the laser marker 10. In step S204, the laser marker 10 confirms that the automatic setting mode has ended and performs processing such as sounding a buzzer to indicate the end depending on the specifications. After this, the user may fine-tune the position of the vertical mark 16b by operating the knob 32 as necessary. Note that the laser marker 10 starts a timer in step S201, and if the light receiver 14 does not receive a transmission signal from steps S102, S104, S105 or S108 within a predetermined time, it may determine that an error has occurred and perform necessary processing such as forcibly terminating the automatic setting mode.

[0106] In the first wide-angle rotation phase in the automatic setting mode, the light projector 18 rotates relatively quickly due to the steady-state characteristics of the DC motor 42. On the other hand, in the second small-angle rotation phase, high-precision rotation over a small angle is required. The required positioning accuracy of the light projector 18 is, for example, about 2 to 6 arc seconds, based on the maximum applicable distance between the laser marking device 10 and the receiver 14, the characteristics of the laser optical system, and other factors. In other words, in the small-angle rotation phase, the angle positioning of the light projector 18 must be controlled with an accuracy of about 2 to 6 arc seconds. To achieve this, braking the motor 42 with one or two pulses output from the rotary encoder 44a requires immediately turning off the power to the motor 42 once it has started to start, minimizing overrun.

[0107] Because a typical DC motor generates maximum torque at startup and has steep operating characteristics, this embodiment uses an electrical damper resistor 98d and a mechanical leaf spring 46 (see FIG. 7) as speed suppression dampers. The damper resistor 98d has the effect of gently increasing the acceleration of the motor 42 when it starts. The leaf spring 46 has the effect of suppressing overrun, which occurs primarily due to inertial rotation. These features ensure the rotational accuracy of the motor 42 corresponding to one to two pulses output from the rotary encoder 44a, and the positioning accuracy of the vertical ink mark 16b within 2 to 6 arc seconds. The damper resistor 98d and leaf spring 46 are designed to have almost no effect on the rotational speed of the motor 42 during the wide-angle rotation phase.

[0108] While the above example illustrates the setting of the vertical mark 16b in the automatic setting mode, automatic setting of the horizontal mark 16a is also possible if the receiver 14 is placed vertically. The signal transmitted from the receiver 14 to the laser marker 10 may not be a specific instruction signal, but may be a code with predefined instructions. In the automatic setting mode, the receiver computer 94b, the light projector computer 96c, and the rotation computer 98a cooperate to function as a motor control unit. However, the processing responsibilities of each computer are not limited to the above example. For example, the receiver computer 94b may directly transmit signals obtained from the right sensor 92a and the left sensor 92b via the input interfaces 94c and 94d to the laser marker 10 without determining the position of the vertical mark 16b or the rotation stop and rotation angle of the motor 42. However, due to the need for control of the illumination of the LEDs 90a-90c, it is preferable for the receiver computer 94b to make various decisions.

[0109] The marking set 12 according to this embodiment has the following first to fourth features. A first feature is a marking set comprising a laser marking device and a light receiver, wherein the laser marking device has a light projecting unit that projects a laser to project a vertical marking line onto an object, and a rotating unit that supports the light projecting unit below and rotates it horizontally, the rotating unit has: a driven gear that rotates integrally with the light projecting unit, a drive gear that drives the driven gear, a motor driven by a motor control unit, a reducer that reduces the rotation of the motor and transmits it to the drive gear, and an encoder provided on the rotating shaft of the motor, the light receiver has: two light receiving elements that are adjacent in the horizontal direction and each detect the vertical marking line, and a transmitting unit that transmits a transmission signal based on the detection values ​​of the two light receiving elements to the laser marking device, and the motor control unit, in an automatic setting mode in which the vertical marking line is positioned on a marking target line between the two light receiving elements, in a first step, rotates the light projecting unit using the motor to move the vertical marking line, In the second stage, after one of the two light receiving elements first detects the vertical marking line, based on the received transmission signal, the motor is controlled to rotate forward or reverse so that the encoder outputs a predetermined number of pulses until the vertical marking line is positioned on the marking target line between the two light receiving elements.

[0110] That is, in the first-stage wide-angle rotation mode, the motor 42 rotates the light projector 18 to move the vertical marking 16b, and in the second-stage small-angle rotation mode, after either the right sensor 92a or the left sensor 92b first detects the vertical marking 16b, the motor 42 is controlled to rotate forward or reverse so that the rotary encoder 44a outputs a predetermined number of pulses until the vertical marking 16b is positioned on the marking target line 92c. In this way, the motor 42 can rotate a small angle with precision based on the signal from the rotary encoder 44a in the second stage, while being capable of relatively high-speed rotation in the first stage. Therefore, only one motor 42 is required, which allows the laser marking device 10 to be made smaller, lighter, have fewer parts, be easier to assemble, and be less expensive.

[0111] A second feature is that, in the marking set according to the first feature, the motor control unit reverses the rotation of the motor by decreasing the predetermined number of pulses within a range that does not become 0 each time the vertical marking line passes the target marking line. With this type of control, the vertical marking 16b can be positioned simply and reliably based on basically only pulse signals rather than analog control.

[0112] A third feature is that in the marking set according to the first feature, the receiver transmits a forward rotation signal as the transmission signal when one of the two light receiving elements detects the vertical marking line, and transmits a reverse rotation signal as the transmission signal when the other detects the vertical marking line, and the motor control unit rotates the motor forward or reverse based on the forward rotation signal or the reverse rotation signal. In this way, by determining the position of the vertical marking line and the rotation direction of the motor on the receiver side, the processing load on the laser marking device is reduced and the communication direction can be limited to one direction, from the receiver to the laser marking device.

[0113] A fourth feature is the marking set according to the third feature, wherein the light receiver transmits a pause signal as the transmission signal prior to transmitting the forward rotation signal or the reverse rotation signal when one of the two light receiving elements first detects the vertical marking line in the automatic setting mode, and the motor control unit pauses the motor based on the pause signal. Such a pause enables stable operation of the small angle in the second stage.

[0114] The present invention is not limited to the above-described embodiment, and can of course be freely modified within the scope of the gist of the present invention.

[0115] 10 Laser marking device 12 Marking device set 14 Light receiver 16 Marking line 16b Vertical marking (vertical marking line) 18 Light projecting unit 20 Rotating unit 24 Housing 24a Disk unit 24b Bulging unit 28 Drive mechanism unit 32 Knob 32a Knob shaft 32b Knob worm 34 Control board 36 Driven gear 42 Motor 42b Motor shaft 42ba Tip 42c Motor worm 44 Sensor box 44a Rotary encoder 46 Leaf spring (elastic body) 48 Resin piece 50 Reducer 54 First drive wheel 56 Drive gear 58 Planetary gear mechanism 60 Second drive wheel 64 Sun gear 66 Ring gear 68 Pinion gear 70 Carrier 72 First member 74 Second member 76 Spring 78 First gear 80 Second gear 82 Spring 86 Light receiving window 92a Right sensor 92b Left sensor 92c Marking target line 94b Light receiver computer 94e Transmission module 96c Light projecting unit computer 96d Receiving module 98a Rotating unit computer 98d Damper resistor

Claims

1. A laser marking device having a light-projecting unit that projects a laser marking line onto an object, and a rotating unit that supports the light-projecting unit and rotates it horizontally, wherein the rotating unit comprises: a motor, a driven gear that rotates integrally with the light-projecting unit, a drive gear that drives the driven gear, a knob that is rotated by hand, a planetary gear mechanism comprising a sun gear, a ring gear, a carrier and multiple pinion gears, a first drive wheel that is arranged coaxially with the sun gear over 360 degrees and rotates integrally with the sun gear, a second drive wheel with external teeth arranged over 360 degrees on the outer periphery of the ring gear, a motor worm attached to the rotating shaft of the motor, and a knob worm attached to the rotating shaft of the knob, wherein the first drive wheel meshes with the motor worm, and the second drive wheel meshes with the knob worm.

2. A laser marking device as described in claim 1, characterized in that it has a backlash suppression means for suppressing backlash between the drive gear and the driven gear.

3. The laser marking device according to claim 1, characterized in that an encoder is provided on the rotating shaft of the motor, and a signal from the encoder is supplied to a control unit of the motor.

Images