Linear motor and three dimensional scanner using the same

Abstract

The present disclosure provides a linear motor that can be reduced in size, is easily controlled, and can be reduced in manufacturing cost, and a three dimensional scanner using the linear motor.SOLUTION: The linear motor 801 includes a mover 190 having a permanent magnet 53, a stator having a coil 52 disposed at a position facing the permanent magnet 53, and a linear guide 60 that guides the mover 190 so as to linearly move. The mover 190 is attached to the linear guide 60 by fitting a support portion 180 provided on the linear guide 60 and a holding portion 160 provided on the mover 190 corresponding to the support portion 180. The coil 52 includes a plate-shaped yoke 51 and a winding 54 wound around the yoke 51. The winding 54 is continuously wound around the yoke 51 so as to have a first region 51a where the winding 54 is wound around the yoke 51 in a first winding direction and a second region 51b where the winding 54 is wound around the yoke 51 in a second winding direction opposite to the first winding direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a linear motor and a three-dimensional scanner using the same. [Background technology]

[0002] Conventionally, 3D scanners have been known as medical diagnostic devices that scan the teeth and surrounding soft tissues in the oral cavity to obtain 3D shape data. For example, Patent Document 1 (Japanese Patent No. 6883559) discloses a scanner that uses a linear motor to move a lens and a counterweight in a straight line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6883559 Summary of the Invention [Problem to be solved by the invention]

[0004] The 3D scanner disclosed in Patent Document 1 uses multiple support parts on the object side and multiple holding parts on each of the linear guides, each fitted with a certain amount of play, to linearly move the lens and counterweight with a linear motor, minimizing the impact of assembly errors. However, the linear motor disclosed in Patent Document 1 requires the current flowing through the coils before and after the linear motion of the lens to be reversed. This requires the coils to be formed into an arc-shaped flat spiral coil. This results in a larger coil, which increases the size of the linear motor and complicates its structure. While linear motors with separate coils before and after the linear motion of the lens could be considered, this increases the complexity of controlling the two coils and increases manufacturing costs.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a linear motor that can be miniaturized, is easy to control, and can reduce manufacturing costs, and a 3D scanner using the same. [Means for solving the problem]

[0006] The linear motor according to the present disclosure is a linear motor that performs reciprocating linear motion and includes a mover having a permanent magnet, a stator having a coil positioned opposite the permanent magnet, and a linear guide that guides the mover so that it moves reciprocating linearly in a direction parallel to the alignment direction of a pair of magnetic poles of the permanent magnet. The coil includes a plate-shaped yoke and a winding wound around the yoke. The winding is wound around the yoke so as to have a first region wound around the yoke in a first winding direction and a second region wound around the yoke in a second winding direction opposite the first winding direction. The coil is arranged so that the alignment direction of the first region and the second region is parallel to the alignment direction of the pair of magnetic poles of the permanent magnet, and the first winding direction and the second winding direction are perpendicular to the alignment direction of the pair of magnetic poles of the permanent magnet.

[0007] The three-dimensional scanner according to the present disclosure is a three-dimensional scanner that acquires the three-dimensional shape of an object using focusing technology. The three-dimensional scanner comprises the above-mentioned linear motor, a lens held by a movable element, a light source, a pattern generating element that is provided between the lens and the object and generates a projection pattern on the object using light from the light source, an optical sensor that moves the lens back and forth along the same line using the linear motor, changes the focal position of the projection pattern projected onto the object, and detects light from the object for each change, and a control unit that calculates shape information of the three-dimensional shape of the object based on the position of the lens and the detection result by the optical sensor at that position. [Effects of the Invention]

[0008] In the present disclosure, a coil is used in which the winding is wound around a yoke so as to have a first region in which the winding is wound around the yoke in a first winding direction and a second region in which the winding is wound around the yoke in a second winding direction that is opposite to the first winding direction. This makes it possible to realize a linear motor that can be made small, is easy to control, and keeps manufacturing costs down, as well as a medical diagnostic device that uses the same. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the configuration of a three-dimensional scanner according to an embodiment. [Figure 2] 1A is a schematic diagram showing the configuration of a handpiece according to an embodiment, and FIG. 1B is a schematic diagram showing an XZ cross section of the handpiece according to an embodiment. [Figure 3] 3A and 3B are diagrams for explaining the positional relationship between a lens and a counterweight in the three-dimensional scanner according to the embodiment. [Figure 4] 1 is a perspective view of a linear motor according to an embodiment; [Figure 5] 1 is an exploded perspective view of a linear motor according to an embodiment; [Figure 6] 1 is a cross-sectional view of a linear motor according to an embodiment taken along an XY cross section. [Figure 7] FIG. 2 is a perspective view of a coil according to an embodiment. [Figure 8] FIG. 2 is a cross-sectional view of a coil according to an embodiment. [Figure 9] FIG. 2 is a perspective view of a yoke according to the embodiment. [Figure 10] 2 is a diagram for explaining a magnetic circuit of a linear motor according to an embodiment. FIG. [Figure 11] FIG. 10 is a schematic diagram showing the configuration of a cutting device, which is a medical treatment device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. <Embodiment> First, the configuration of a medical diagnostic device according to an embodiment of the present disclosure will be described. In the embodiment, a 3D scanner that can be used in dental diagnostics will be described as an example of a diagnostic device. The 3D scanner is an intraoral scanner for acquiring the 3D shape of teeth in the oral cavity. The 3D scanner according to the embodiment is not limited to an intraoral scanner, but can also be applied to other 3D scanners having a similar configuration, such as a scanner that acquires the 3D shape of the inside of a human ear by imaging the inside of the human ear in addition to the oral cavity. Furthermore, the medical diagnostic device is not limited to a 3D scanner, but can also be applied to a medical diagnostic device that drives a cutting tool.

[0011] Furthermore, the medical diagnostic device according to the embodiment is applicable not only to dentistry but also to all medical fields such as ophthalmology, otolaryngology, radiology, internal medicine, surgery, and veterinary medicine. Note that diagnostics include diagnosis and treatment.

[0012] [3D scanner configuration] FIG. 1 is a schematic diagram showing the configuration of a three-dimensional scanner 100 according to an embodiment. The three-dimensional scanner 100 corresponds to one embodiment of a "medical diagnostic device." As shown in FIG. 1, the three-dimensional scanner 100 includes a handpiece 70, a control unit 40, a display unit 50, and a power supply 45. The handpiece 70 is a handheld member, and includes a probe 10, a connection unit 20, and an optical measurement unit 30.

[0013] The probe 10 is inserted into the oral cavity and projects light having a pattern (hereinafter simply referred to as the pattern) onto an object 99 such as a tooth. The probe 10 guides the light reflected from the object 99 onto which the pattern is projected to the optical measurement unit 30. The probe 10 covers the outer periphery of the tip of the connection unit 20 and is detachably attached to the connection unit 20. Therefore, as a countermeasure against infection, the surgeon can remove only the probe 10 that may come into contact with a living body from the optical measurement unit 30 and perform sterilization processing (for example, autoclaving in a high-temperature, high-humidity environment).

[0014] The connection part 20 is a part of the optical measurement part 30, protruding from the optical measurement part 30, and has a shape that can fit into the base of the probe 10. The connection part 20 includes optical components such as a lens system for guiding light collected by the probe 10 to the optical measurement part 30, a cover glass, an optical filter, and a retardation plate (a quarter wave plate).

[0015] The optical measurement unit 30 projects a pattern onto the object 99 via the probe 10 and captures an image of the projected pattern. As will be described below, the optical measurement unit 30 according to the embodiment is configured to acquire a three-dimensional shape using the principle of focusing, but may also be configured to acquire a three-dimensional shape using the principle of focusing, trigonometry, or confocal method. In other words, the optical measurement unit 30 may be configured using any principle as long as it includes a configuration that changes the position of the focal point of the projection pattern or the optical sensor and acquires a three-dimensional shape using an optical method.

[0016] The control unit 40 controls the operation of the optical measurement unit 30 and processes images captured by the optical measurement unit 30 to obtain a three-dimensional shape. Although not shown, the control unit 40 includes a CPU (Central Processing Unit) as a control center, a ROM (Read Only Memory) that stores programs and control data for the CPU to operate, a RAM (Random Access Memory) that functions as a work area for the CPU, and an input / output interface for maintaining signal consistency with peripheral devices. The control unit 40 can also output the obtained three-dimensional shape to a display unit 50, and can also input information such as settings for the optical measurement unit 30 using an input device (not shown).

[0017] At least a portion of the calculations for processing captured images to obtain a three-dimensional shape may be implemented as software by the CPU of the control unit 40, or may be implemented as hardware that performs processing separately from the CPU. At least a portion of the processing units, such as the CPU and hardware, may be incorporated into the optical measurement unit 30. In FIG. 1, the components (30, 40, 45, 50) of the 3D scanner 100 are depicted as being wired by cables (thick lines in the figure), but some or all of these wires may be connected via wireless communication. If the control unit 40 is small and lightweight enough to be picked up with one hand, the control unit 40 may be provided inside the handpiece 70.

[0018] The display unit 50 displays the measurement results of the three-dimensional shape of the object 99 obtained by the control unit 40. The display unit 50 can also display other information such as setting information for the optical measurement unit 30, patient information, the startup status of the scanner, an instruction manual, and a help screen. The display unit 50 can be, for example, a stationary liquid crystal display or a head-mounted or eyeglass-type wearable display. Furthermore, there may be multiple display units 50, and the three-dimensional shape measurement results and other information may be displayed simultaneously or in separate displays on multiple display units 50.

[0019] The power supply 45 supplies power to the optical measurement unit 30 and the control unit 40. The power supply 45 may be provided outside the control unit 40 as shown in Fig. 1, or may be provided inside the control unit 40 or inside the handpiece 70. Furthermore, a plurality of power supplies 45 may be provided so that power can be supplied individually to the control unit 40, the optical measurement unit 30, and the display unit 50.

[0020] [Handpiece configuration] Fig. 2(A) is a schematic diagram showing the configuration of a handpiece 70 according to an embodiment. Fig. 2(B) is a schematic diagram showing an XZ cross section of the handpiece 70 according to an embodiment. Note that each member in the handpiece 70 shown in Fig. 2 is housed in the optical measurement unit 30 shown in Fig. 1.

[0021] As shown in FIG. 2, handpiece 70 includes a housing 77 containing a projection light generator 75, a lens 81, an optical sensor 71, and a prism 72. In addition to these, handpiece 70 may also include a reflector that reflects light toward an object 99. Lens 81 is held by a mover of a linear motor, which will be described later. In the embodiment described below, for the sake of convenience, an imaginary line representing the direction in which lens 81 moves back and forth linearly is indicated by L, and an axis parallel to line L is referred to as the X-axis (first axis), an axis perpendicular to line L and pointing upward on the paper surface in FIG. 2 is referred to as the Z-axis, and an axis perpendicular to both the X-axis and the Z-axis is referred to as the Y-axis (second axis).

[0022] The projection light generating unit 75 is a laser element or an LED (Light Emitting Diode) that serves as a light source. The light from the projection light generating unit 75 passes through a projection pattern screen (not shown) that generates a projection pattern and is disposed in front of the projection light generating unit 75, passes through the prism 72 and the lens 81, and is then irradiated onto the object 99 via a reflecting unit 66 provided on the probe 10 and reflected by the object 99. The light reflected by the object 99 passes through the lens 81 again via the reflecting unit 66 and enters the prism 72. The prism 72 changes the traveling direction of the light from the object 99 to the direction where the optical sensor 71 is located (in this example, the Z-axis direction). The light whose traveling direction has been changed by the prism 72 is detected by the optical sensor 71. In the example shown in FIG. 2(B), the light from the projection light generating unit 75 and the light reflected by the object 99 and guided to the prism 72 are shown separately, but this is for ease of explanation, and in reality, the handpiece 70 is configured so that both types of light are guided coaxially.

[0023] When a three-dimensional shape is acquired using the focusing technique, light that passes through a pattern generating element (not shown) provided between the lens 81 and the object 99 is projected onto the object 99. When the lens 81 moves back and forth along the same straight line (for example, the straight line L in the figure), the focal position of the projected pattern changes. The optical sensor 71 detects the light from the object 99 with each change. The above-mentioned control unit 40 calculates shape information of the object 99 based on the position of the lens 81 and the detection result by the optical sensor 71 at that time.

[0024] The lens 81 is driven by the first drive unit 80 and moves linearly back and forth. When the lens 81 moves linearly back and forth in the direction of the line L (the X-axis direction), the center of gravity of the handpiece 70 moves by an amount equal to the mass of the lens 81, and this is transmitted as vibration to the hand of the user holding the handpiece 70. To cancel out this vibration, the handpiece 70 is further provided with a counterweight 91 inside the housing 77. The counterweight 91 is driven by the second drive unit 90 and moves linearly back and forth in a direction relative to the lens 81.

[0025] The counterweight 91 is provided on the rear side of the projection light generating unit 75 in the X-axis direction so as not to block the optical path between the object 99 and the lens 81 and the optical path between the lens 81 and the optical sensor 71.

[0026] 2(B), handpiece 70 is provided with a first housing portion 501 located in front of handpiece 70 and a second housing portion 502 located in rear of handpiece 70 within housing 77. Lens 81 is accommodated in first housing portion 501, and counterweight 91 is accommodated in second housing portion 502. Furthermore, handpiece 70 is provided with a connecting housing portion 500 between first housing portion 501 and second housing portion 502, which connects lens 81 held by first housing portion 501 to counterweight 91 held by second housing portion 502. Connecting housing portion 500 accommodates optical sensor 71, prism 72, and projection light generator 75 described above.

[0027] Figure 3 is a schematic diagram for explaining the positional relationship between lens 81 and counterweight 91 in three-dimensional scanner 100 according to the embodiment. Note that housing 77 is omitted in the example shown in Figure 3. As shown in Figure 3, lens 81 is supported by linear guide 60 parallel to line L so as to perform reciprocating linear motion in the direction of line L.

[0028] Furthermore, the first driving unit 80 causes the lens 81 held by the mover to perform a linear reciprocating motion in the direction of the line L by means of the magnetic circuit configuration 85. In other words, the first driving unit 80 is configured by a linear motor.

[0029] Counterweight 91 is a weight that is provided on line L in the linear motion direction of lens 81 and has the same mass as lens 81. Counterweight 91 is supported by linear guide 65 that is parallel to line L so as to move back and forth linearly in the direction of line L. In the embodiment, linear guide 60 and linear guide 65 are different members, but linear guide 60 and linear guide 65 may also be configured as a single continuous member.

[0030] Furthermore, the second driving unit 90 causes a counterweight 91 held by the mover to perform a linear reciprocating motion in the direction of a straight line L by means of a magnetic circuit configuration 95. In other words, the second driving unit 90 is composed of a linear motor.

[0031] The specific configurations of the first drive unit 80 and the second drive unit 90, which are linear motors, will be described later. In the following, the first drive unit 80 and the second drive unit 90 will also be collectively referred to simply as "linear motors." The first drive unit 80 and the second drive unit 90 are each controlled by the control unit 40. In the embodiment, the first drive unit 80 and the second drive unit 90 are each controlled by the common control unit 40, but the first drive unit 80 and the second drive unit 90 may each be controlled by different control units.

[0032] When the first drive unit 80 causes the lens 81 to move back and forth in the direction of the straight line L that serves as the optical axis, the second drive unit 90 causes the counterweight 91 to move back and forth in the direction opposite the lens 81 by the same distance as the lens 81. For example, when the lens 81 moves 10 mm on the straight line L in a direction approaching the object 99, the counterweight 91 moves 10 mm on the straight line L in a direction away from the object 99. Furthermore, when the lens 81 moves 15 mm on the straight line L in a direction away from the object 99, the counterweight 91 moves 15 mm on the straight line L in a direction approaching the object 99.

[0033] In this way, the counterweight 91 moves linearly back and forth in the direction opposite to the lens 81 by the same distance as the lens 81, thereby offsetting the deviation of the center of gravity of the handpiece 70 caused by the linear reciprocating motion of the lens 81. As a result, the counterweight 91 can cancel out vibrations caused by the linear reciprocating motion of the lens 81.

[0034] [Linear motor configuration] Next, a specific configuration of the linear motor will be described with reference to the drawings. FIG. 4 is a perspective view of linear motor 801 according to an embodiment. FIG. 5 is an exploded perspective view of linear motor 801 according to an embodiment. FIG. 6 is a cross-sectional view of linear motor 801 according to an embodiment in an XY cross section. In the example shown in FIGS. 4 to 6, the configuration of linear motor 801 corresponding to first drive unit 80 will be described, but the configuration of linear motor corresponding to second drive unit 90 is also similar to that of linear motor 801. That is, in the case of the linear motor corresponding to second drive unit 90, in the example shown in FIGS. 4 to 6, lens 81 is replaced with counterweight 91, but the other configurations are similar to that of linear motor 801.

[0035] Linear motor 801 has a magnetic circuit configuration 85 including a yoke 51, coils 52, and permanent magnets 53. Linear motor 801 also has a mover 190 that holds lens 81 so as to surround the outer periphery of lens 81, and permanent magnets 53 are provided above and below mover 190 in the figure. Note that the yoke 51 and coils 52 that are positioned opposite permanent magnet 53 form the stator of linear motor 801. Permanent magnet 53 is fixed to mover 190 and arranged so that, for example, N pole 53a faces the positive direction of the X-axis and S pole 53b faces the negative direction of the X-axis.

[0036] The mover 190 has an opening in the direction of linear motion, and holds a lens 81 (optical component) in the opening, so that the optical path between the target object 99 and the optical sensor 71 passes through the opening. One end of the mover 190 holding the lens 81 abuts against a spring 55a, and the other end of the mover 190 abuts against a spring 55b.

[0037] 6, linear motor 801 has two linear guides 60, each consisting of a rail 57 and a block 56, arranged in parallel on the outer periphery of mover 190. The two linear guides 60 are arranged at different positions on the outer periphery of mover 190.

[0038] More specifically, the two linear guides 60 are arranged parallel to each other in rotational symmetry with the optical axis (straight line L) that is parallel to the linear motion direction of the lens 81 and passes through the center of the lens 81 as the rotation axis.

[0039] The linear guide 60 includes a block 56 and a rail 57. The block 56 supports the mover 190 and the lens 81 and is fitted to the rail 57, and moves linearly along the rail 57 to cause the lens 81 to move back and forth linearly. A viscous lubricant such as grease may be applied between the block 56 and the connecting surface of the rail 57, or a rolling bearing such as a ball or roller may be provided.

[0040] 5, springs 55a and 55b are provided to surround the outer periphery of lens 81 so as not to block the optical path at the center of lens 81. Springs 55a and 55b correspond to one embodiment of an elastic member. Springs 55a and 55b may be coil springs or the like. Note that the elastic member is not limited to a spring, and any member, such as rubber, that deforms when a force is applied and returns to its original shape when the force is removed may be used.

[0041] One end of each of springs 55a and 55b abuts against mover 190, and the other end is fixed to housing 59 of linear motor 801. Furthermore, springs 55a and 55b are held within housing 59 so as to allow deformation in the X direction and to make deformation in the Y and Z directions difficult. Springs 55a and 55b arranged in this manner apply an elastic force to mover 190 in the linear motion direction. It is preferable that the diameter of each of springs 55a and 55b be approximately the same as the diameter of lens 81 so as not to block the optical path passing through lens 81.

[0042] Lens 81, together with mover 190, is supported by linear guide 60 via support portion 180 and holding portion 160 so as to be capable of reciprocating linear motion. Specifically, holding portion 160 is provided on a portion of mover 190 that holds lens 81. Support portion 180 is screwed to a portion of block 56 that moves on rail 57. Support portion 180 and holding portion 160 are fitted together.

[0043] In this way, the support part 180 screwed to the linear guide 60 side and the holding part 160 provided on the movable element 190 side are fitted together, so that the movable element 190 including the lens 81 can move back and forth in a straight line along the rail 57.

[0044] Coil 52 is not a flat spiral coil, but a solenoid coil in which a winding is wound around a plate-like yoke. Specifically, FIG. 7 is a perspective view of coil 52 according to the embodiment. FIG. 8 is a cross-sectional view of coil 52 according to the embodiment. FIG. 9 is a perspective view of yoke 51 according to the embodiment. As shown in FIG. 7, coil 52 has a first region 52a in which winding 54 is wound around yoke 51 in a counterclockwise direction (first winding direction) facing the positive direction of the X-axis, and a second region 52b in which winding 54 is wound around yoke 51 in a clockwise direction (second winding direction) facing the positive direction of the X-axis. Winding 54 starts from notch 510a in resin part 51a, continues through first region 52a and second region 52b, and ends at notch 510b in resin part 51b. Since the winding direction of the winding wire 54 changes between the first region 52a and the second region 52b, the winding direction of the winding wire 54 is switched at the notched portion 510c of the resin portion 51c.

[0045] As shown in FIG. 8(A), coil 52 has winding 54 wound on both sides of yoke 51. While the configuration in which winding 54 is wound around yoke 51 in one layer has been described, winding 54 may be wound around yoke 51 in two or more layers. As shown in FIG. 8(B), resin portion 51c has winding 54 only in cutout portion 510c, and no winding 54 in other portions. On the other hand, in portions where resin portions 51a to 51c are not provided, no winding 54 exists so as to surround yoke 51, as shown in FIG. 8(C). Resin portion 51d is provided on the side of yoke 51 to prevent wound winding 54 from being damaged by the corners of yoke 51.

[0046] As shown in FIG. 9 , the yoke 51 is made of a metal plate (e.g., permalloy, silicon steel, low-carbon steel, etc.) that has been formed into a plate shape, and resin portions 51a-51d are integrally molded by outsert molding. That is, the resin portions 51a-51d function as bobbins for the coil 52, and the yoke and the bobbin can be integrally molded by outsert molding the resin portions 51a-51d onto the yoke 51. Alternatively, the resin portions 51a-51d may be molded separately and then individually attached to the yoke 51. The region between the resin portions 51a and 51c is the first region 52a, and the region between the resin portions 51b and 51c is the second region 52b. If the lens 81 is to move back and forth linearly from a central position, as in a three-dimensional scanner, it is preferable that the first region 52a and the second region 52b have the same area. Of course, the first region 52a and the second region 52b may have different areas.

[0047] Furthermore, although coil 52 is provided with resin portion 51c to switch the winding direction of wire 54 between first region 52a and second region 52b, the end of wire 54 may be fixed at the position where the winding direction switches without providing resin portion 51c. The width (length in the X-axis direction) of resin portion 51c may be determined appropriately depending on the object to be driven, but making it thinner allows coil 52 to be made more compact. Also, although the description has been given with resin portion 51a at the start of wire 54 and resin portion 51b at the end, this may be reversed, and wire 54 may be fixed at the start and end positions without providing resin portions 51a and 51b.

[0048] A magnetic circuit will be described when linear motor 801 employs coil 52, which is a solenoid coil. FIG. 10 is a diagram for explaining the magnetic circuit of linear motor 801 according to the embodiment. When permanent magnet 53 is arranged so that north pole 53a and south pole 53b are positioned relative to coil 52 as shown in FIG. 10, a magnetic field is generated in the direction of the dotted arrow. In coil 52, currents as shown in FIG. 10 (currents flowing from the front of the page to the back of the page along the Y axis are indicated by "x" and currents flowing from the back of the page to the front of the page along the Y axis are indicated by "·") are passed through first region 52a and second region 52b of coil 52.

[0049] When a current is passed through coil 52, an electromagnetic force (F) is generated in the direction of the arrow shown by the solid line (X-axis direction) according to Fleming's left-hand rule. The reaction force of the electromagnetic force (F) generated in this way acts on permanent magnet 53 provided in mover 190, causing lens 81 to move in the direction opposite to the electromagnetic force (F). Since lens 81 can be moved in the opposite direction by reversing the direction of the current passed through coil 52, linear motor 801 can cause lens 81 to perform a reciprocating linear motion by periodically changing the direction of the current passed through coil 52.

[0050] As shown in FIG. 10 , the current flowing through the coil 52 on the side facing the permanent magnet 53 across the yoke 51 contributes to the electromagnetic force (F), but the current flowing on the opposite side does not contribute to the electromagnetic force (F). The coil 52 is also configured with a single winding 54, which defines a first region 52a and a second region 52b with different winding directions. Therefore, simply by passing a current through the winding 54, the coil 52 can pass currents in the first region 52a and the second region 52b with the same phase shift but in opposite directions due to the magnetic circuit configuration. If the first region 52a and the second region 52b were configured with different windings, the control of the two coils would become complicated and the manufacturing costs would increase. However, the coil 52 does not have such problems because the first region 52a and the second region 52b are configured with a single winding 54.

[0051] [Variation] The present disclosure is not limited to the above-described embodiments, and various modifications and applications are possible. Modifications applicable to the present disclosure will be described below.

[0052] The configuration of linear motor 801 described above is one example, and the number of springs and their locations, as well as the number of linear guides and their locations, can be designed by appropriately combining them in consideration of the space inside the handpiece. Furthermore, linear motor 801 has two combinations of permanent magnets 53 and coils 52 arranged in positions facing permanent magnets 53, one above and one below mover 190, as shown in Fig. 5, but it may have either one, or three or more.

[0053] In the above-described embodiment, the support portion 180 having the convex portion 184 protruding toward the mover 190 is provided on the linear guide 60 side, and the retainer portion 160 having the concave portion 164 that fits into the convex portion 184 is provided on the mover 190 side. However, the support portion 180 may be provided on the mover 190 side, and the retainer portion 160 may be provided on the linear guide 60 side. Furthermore, the shapes of the convex portion 184 and the concave portion 164 are not limited to cylindrical shapes, and may be other shapes. For example, the convex portion 184 may have a spherical shape that protrudes outward toward the mover 190 side, and the concave portion 164 may have a spherical depression.

[0054] In the embodiment, a 3D scanner has been described as an example of a medical diagnostic device, but the medical diagnostic device can also be used for other purposes. For example, the medical diagnostic device may be a cutting device that cuts or scrapes off an object using a cutting tool (e.g., a scaler tip, a root canal treatment file, etc.).

[0055] 11 is a schematic diagram showing the configuration of a cutting device 370, a medical diagnostic device according to a modified example. As shown in FIG. 11, the cutting device 370 includes a housing 375, a cutting tool 385, a cutting holder 381 that holds the cutting tool 385, a first drive unit 580 that reciprocates the cutting holder 381, a counterweight 391 that is disposed on a line in the linear motion direction of the cutting holder 381 and has the same mass as the cutting holder 381, a second drive unit 590 that reciprocates the counterweight 391, a linear guide 360 ​​that guides the cutting holder 381 so that the cutting holder 381 reciprocates, a linear guide 365 that guides the counterweight 391 so that the counterweight 391 reciprocates, and a control unit 340 that controls the first drive unit 580 and the second drive unit 590. The counterweight 391 may have the same mass as the cutting holder 381 plus the cutting tool 385. The control unit 340 controls the first driving unit 580 and the second driving unit 590 so that the cutting holder 381 and the counterweight 391 reciprocate linearly in opposing directions by the same distance.

[0056] In this way, in the cutting device 370, the control unit 340 independently controls the first drive unit 580, which moves the cutting holder 381 in a reciprocating linear motion, and the second drive unit 590, which moves the counterweight 391 in a reciprocating linear motion, so that the cutting tool 385 held by the cutting holder 381 can cut or scrape off an object (for example, a tooth), while the counterweight 391 can minimize residual vibration caused by the reciprocating linear motion of the cutting holder 381.

[0057] In the cutting device 370 shown in FIG. 11, the control unit 340 is housed within the housing 375, but as in the three-dimensional scanner 100 shown in FIG. 1, the control unit 340 may be arranged outside the housing 375 and connected to the first drive unit 580 and the second drive unit 590 by wiring.

[0058] Furthermore, the medical diagnostic device may be a medical camera for taking images of the inside of the oral cavity, the inside of the outer ear, or digestive organs such as the stomach and intestines. In this case, the lens of the camera may be used as the object held by the mover of the linear motor, and a counterweight may be used as another mover.

[0059] Furthermore, a microscope may be used as the medical diagnostic device. In this case, a lens in the microscope may be used as the object held by the mover of the linear motor, and a counterweight may be used as another mover.

[0060] Furthermore, the medical treatment device may be a laser pointer that uses a laser beam to point to an object such as a diagram, or a laser device that cuts teeth. In this case, a lens may be used as an object held by a mover of a linear motor, and a counterweight may be used as another mover.

[0061] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. Note that the configurations exemplified in the embodiments and the configurations exemplified in the modified examples can be combined as appropriate. [Explanation of symbols]

[0062] 10 probe, 20 connection part, 30 optical measurement part, 40,340 control part, 45 power supply, 50 display part, 51 yoke, 51a to 51d resin part, 52 coil, 52a first region, 52b second region, 53 permanent magnet, 55a, 55b spring, 56 block, 57 rail, 60, 65, 360, 365 linear guide, 66 reflecting part, 70 handpiece, 71 optical sensor, 72 prism, 75 projection light generating part, 77 housing, 80, 580 first drive part, 81 lens, 85, 95 magnetic circuit configuration, 90, 590 second drive part, 91, 391 counterweight, 99 object, 100 3D scanner, 160 holding part, 161 holding part main body, 164 recess, 180 support part, 181 Support body, 184 convex portion, 190 mover, 370 cutting device, 375 housing, 381 cutting holding portion, 385 cutting tool, 500 connecting accommodating portion, 501 first accommodating portion, 502 second accommodating portion, 801 linear motor.

Claims

1. A linear motor that performs reciprocating linear motion, a mover having a permanent magnet; a stator having a coil arranged in a position facing the permanent magnet; a linear guide that guides the mover so that it moves linearly back and forth in a direction parallel to the direction in which the pair of magnetic poles of the permanent magnet are aligned, The coil includes a plate-shaped yoke and a winding wound around the yoke, the winding is wound around the yoke to have a first region wound around the yoke in a first winding direction and a second region wound around the yoke in a second winding direction opposite to the first winding direction; the coil is arranged such that the alignment direction of the first region and the second region is parallel to the alignment direction of the pair of magnetic poles of the permanent magnet, A linear motor, wherein the first winding direction and the second winding direction are perpendicular to the direction in which a pair of magnetic poles of the permanent magnet are arranged.

2. The linear motor according to claim 1 , wherein the first region and the second region have the same area.

3. 3. The linear motor according to claim 1, comprising a plurality of combinations of the permanent magnet and the coil arranged in a position facing the permanent magnet.

4. 3. The linear motor according to claim 1, wherein the mover has an elastic member on at least one of the surfaces perpendicular to the direction of the linear reciprocating motion.

5. 3. The linear motor according to claim 1, wherein the linear guide comprises two linear guides arranged in parallel to guide the mover so that it moves linearly back and forth.

6. 3. The linear motor according to claim 1, wherein the mover has an opening in the direction of the reciprocating linear motion, and an optical component can be held in the opening.

7. 3. The linear motor according to claim 1, wherein the mover has a cutting tool holder that holds a cutting tool.

8. A three-dimensional scanner that acquires a three-dimensional shape of an object using a focusing technique, The linear motor according to claim 1 or 2; a lens held by the movable element; A light source and a pattern generating element provided between the lens and the object, the pattern generating element generating a projection pattern on the object using light from the light source; an optical sensor that causes the lens to move back and forth linearly on the same line using the linear motor, changes the focal position of the projection pattern projected onto the object, and detects light from the object for each change; A three-dimensional scanner comprising: a control unit that calculates shape information of the three-dimensional shape of the object based on the position of the lens and the detection result by the optical sensor at that position.

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