Patent Application
20240390118
This nonprovisional application is based on Japanese Patent Application No. 2023-085376 filed with the Japan Patent Office on May 24, 2023, the entire contents of which are hereby incorporated by reference.
The present disclosure relates to a three-dimensional scanner configured to obtain three-dimensional data of a surface geometry of an object with a focus method and a control method of controlling the three-dimensional scanner.
A three-dimensional scanner that scans a surface geometry of an object such as a tooth and a soft tissue in a mouth cavity to obtain three-dimensional data of the surface geometry has conventionally been known. For example, Japanese Patent Laying-Open No. 2019-180881 discloses a three-dimensional scanner that obtains three-dimensional data of a surface geometry of an object by projecting on the object, light that has passed through a lens while the lens is caused to make reciprocating motion in a linear direction and detecting light reflected at the object.
The three-dimensional scanner disclosed in Japanese Patent Laying-Open No. 2019-180881 includes a handpiece that can be used as being held with a hand of a user such as an operator. While the three-dimensional scanner is used, the handpiece is inclined at various angles. Therefore, a component in a direction of reciprocating motion, of gravity applied to a lens in the handpiece is varied with variation in angle of inclination of the handpiece, and with such variation, a central position of reciprocating motion of the lens may also be varied. Thus, while the three-dimensional scanner is used, the focal position moves away from or comes closer to a tip end of the handpiece and a depth of field which is a range of a focal position of light that passes through the lens may not be stable. Therefore, the user has to bring the handpiece closer to or move the handpiece away from the object in accordance with the angle of inclination of the handpiece in order to set the focal position of the lens onto a portion of the object which is a target of imaging. Depending on skills of the user, three-dimensional data of the surface geometry of the object may not appropriately be obtained.
The present disclosure was made to solve the problem above, and an object thereof is to provide a technique that enables appropriate obtainment of three-dimensional data of a surface geometry of an object.
A three-dimensional scanner according to the present disclosure is configured to obtain three-dimensional data of a surface geometry of an object with a focus method. The three-dimensional scanner includes a lens, an imaging unit configured to take an image of the object located at a focal position of the lens, a lens driver configured to drive the lens to make reciprocating motion in a linear direction, an angle detector configured to detect variation in angle of inclination of the lens with respect to a prescribed direction, and a lens controller configured to control an operation of the lens with variation in angle of inclination detected by the angle detector.
A control method according to the present disclosure is a method of controlling a three-dimensional scanner configured to obtain three-dimensional data of a surface geometry of an object with a focus method. The control method includes, as processing to be performed by a computer, taking an image of the object located at a focal position of a lens provided in the three-dimensional scanner, driving the lens to make reciprocating motion in a linear direction, detecting variation in angle of inclination of the lens with respect to a prescribed direction, and controlling an operation of the lens with variation in angle of inclination detected in the detecting variation.
The foregoing and other objects, features, aspects and advantages of this disclosure will become more apparent from the following detailed description of this disclosure when taken in conjunction with the accompanying drawings.
An embodiment of the present disclosure will be described with reference to the drawings.
Three-dimensional scanner 100 according to the embodiment is applicable also to medical care in every medical department such as an ophthalmology department, an otorhinolaryngology department, a radiology department, internal medicine, surgery, and a veterinary department, without being limited to dentistry. For example, three-dimensional scanner 100 according to the embodiment is not limited to the intra oral scanner but is applicable also to another similarly configured three-dimensional scanner such as a scanner configured to obtain three-dimensional data of a surface geometry of the inside of an outer ear by taking an image of the inside of a human ear other than the inside of the mouth cavity.
Any user of three-dimensional scanner 100, such as an operator including a dentist, a dental nurse, a teacher or a student of a dental college, a dental technician, an engineer of a manufacturer, a worker in a manufacturing factory, and the like, may be applicable so long as the user obtains three-dimensional data of object 99 such as a tooth and a soft tissue with the use of three-dimensional scanner 100. Any subject of scanning by three-dimensional scanner 100, such as a patient at a dentist or a subject in a dental college, may be applicable so long as the subject can be a subject to be scanned by three-dimensional scanner 100.
As shown in
Probe 10 is inserted in the mouth cavity to project light having a pattern (which is simply also referred to as a “pattern” below) onto object 99 such as a tooth and a soft tissue. Probe 10 guides light reflected from object 99 on which the pattern is projected to optical measurement unit 30. Probe 10 is removably attached to connection portion 20 while it covers an outer periphery of a tip end of connection portion 20.
Connection portion 20 is a part of optical measurement unit 30 that protrudes from optical measurement unit 30, and it is in a shape that allows fitting to a root of probe 10. Connection portion 20 includes an optical component such as a lens system for guiding light taken by probe 10 to optical measurement unit 30, a cover glass, an optical filter, and a phase plate (for example, a ¼ wave plate).
Optical measurement unit 30 projects a pattern on object 99 through probe 10 and takes an image of the projected pattern. Optical measurement unit 30 according to the embodiment is configured to obtain a three-dimensional geometry based on principles of the focus method as will be described below.
Control device 40 controls an operation of optical measurement unit 30 and obtains the three-dimensional geometry by processing an image taken by optical measurement unit 30. Control device 40 includes a computing unit 41 and a storage unit 42.
Computing unit 41 is a computing entity (computer) that performs various types of processing by executing various programs. Computing unit 41 is implemented by a processor such as a central processing unit (CPU) or a micro-processing unit (MPU). Though the processor which represents a computing unit 41 performs functions to perform various types of processing by executing a program, some or all of these functions may be performed by dedicated hardware circuitry such as an application specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). The “processor” is not limited to a processor in a narrow sense that performs processing in accordance with a stored program architecture like the CPU or the MPU, but may encompass hard-wired circuitry such as the ASIC or the FPGA. Therefore, the “processor” representing computing unit 41 can also be read as processing circuitry, processing by which is defined in advance by a computer readable code and/or hard-wired circuitry. Computing unit 41 may be implemented by a single chip or a plurality of chips. Furthermore, the processor and relating processing circuitry may be implemented by a plurality of computers connected to one another through wires or wirelessly over a local area network or a wireless network. The processor and the relating processing circuitry may be implemented by a cloud computer that performs remote computation based on input data and outputs a result of computation to another device located at a remote position.
Storage unit 42 includes a memory and a storage device which are not shown. The memory includes a volatile storage area (for example, a working area) where a program code or a work memory is temporarily stored in execution of various programs by computing unit 41. Examples of the memory include a volatile memory such as a dynamic random access memory (DRAM) and a static random access memory (SRAM) or a non-volatile memory such as a read only memory (ROM) and a flash memory. Various programs to be executed by computing unit 41 or various types of data are stored in the storage device. The storage device may be implemented by one or more non-transitory computer readable media or one or more computer readable storage media. Examples of the storage device include a hard disk drive (HDD) and a solid state drive (SSD).
In three-dimensional scanner 100 according to the embodiment, a control program 43 to be executed by computing unit 41 is stored in storage unit 42. Computing unit 41 performs processing involved with amplitude control for controlling reciprocating linear motion of a lens 81 by executing control program 43. Details of amplitude control will be described later.
Control device 40 can also output obtained three-dimensional data to display 50 or receive input of information such as setting of optical measurement unit 30 through a not-shown input device or the like.
Though control device 40 is configured separately from handpiece 70 in three-dimensional scanner 100 according to the embodiment, at least one or all of functions of computing unit 41 and storage unit 42 of control device 40 may be performed by handpiece 70 so long as control device 40 is sufficiently small in size and light in weight to such an extent as being lifted by one hand.
Though each constituent element (30, 40, 45, or 50) of three-dimensional scanner 100 is drawn as being routed through a cable (a bold line in the figure) in the example in
Display 50 shows a three-dimensional geometry of object 99 represented by three-dimensional data obtained by control device 40. Display 50 can also show other information such as setting information of optical measurement unit 30, patient information, a scanner activation state, an operation manual, and a help screen. For example, a stationary liquid crystal display, a wearable device of a head-mounted type or a glass type, or the like may be applicable as display 50. Three-dimensional scanner 100 may include a plurality of displays 50, and the three-dimensional geometry of object 99 and other information may be shown on the plurality of displays 50 simultaneously or in a split manner.
Power supply 45 supplies electric power to optical measurement unit 30 and control device 40. Though power supply 45 may be provided outside control device 40 as shown in
As shown in
Projection light generator 75 is implemented by a laser element or a light emitting diode (LED) that serves as a light source. Light from projection light generator 75 passes through prism 72 and lens 81 via a projection pattern screen (not shown) that is arranged in front of projection light generator 75 and generates a projection pattern, and is emitted to object 99 through a reflection portion 66 provided in probe 10 and reflected by object 99. Light reflected at object 99 passes again through lens 81 via reflection portion 66 and enters prism 72. Prism 72 changes a direction of travel of light from object 99 to a direction in which optical sensor 71 is located (in this example, a Z-axis direction). Light the direction of travel of which is changed by prism 72 is detected by optical sensor 71. Though light from projection light generator 75 and light reflected at object 99 and guided to prism 72 are shown separately from each other in the example shown in
In an example where a three-dimensional geometry is obtained by using the technique of the focus method, light that passes through a pattern generation element (not shown) provided between lens 81 and object 99 is projected on object 99. As lens 81 makes reciprocating linear motion along the same straight line (for example, straight line L as illustrated), a focal position of the projection pattern is varied. Optical sensor 71 takes an image of object 99 present at the focal position of the projection pattern by detecting light from object 99 at a prescribed frame rate each time the focal position of the projection pattern is varied, under the control by control device 40. Since control device 40 can change the frame rate by changing a shutter speed of optical sensor 71, it performs a function as a “frame rate controller.” Control device 40 obtains three-dimensional data of the surface geometry of object 99 by computing geometrical information of object 99 based on a position of lens 81 and a result of detection by optical sensor 71 at that time.
Lens 81 is driven by a lens driver 80 and makes reciprocating linear motion. When lens 81 makes reciprocating linear motion in a direction shown with straight line L (an X-axis direction), a position of the center of gravity of handpiece 70 moves by a mass of lens 81, which is transmitted as vibration to a user's hand with which handpiece 70 is held. In order to cancel vibration, handpiece 70 further includes a counterweight 91 in the inside of housing 77. Counterweight 91 is driven by a counterweight driver 90 and makes reciprocating linear motion in a direction opposite to reciprocating motion of lens 81.
Counterweight 91 is provided on a rear surface side of projection light generator 75 in the X-axis direction so as not to cut off an optical path between object 99 and lens 81 and an optical path between lens 81 and optical sensor 71.
Specifically, as shown in
Furthermore, lens driver 80 causes lens 81 held by a mover to make reciprocating linear motion in the direction of straight line L by means of magnetic circuitry 85. In other words, lens driver 80 is implemented by a linear motor.
Counterweight 91 is a weight provided on straight line L in a direction of the linear motion of lens 81, the weight being equal in mass to lens 81. Counterweight 91 is supported by a linear guide 65 in parallel to straight line L to make reciprocating linear motion in the direction of straight line L. Though linear guide 60 and linear guide 65 are different members in the embodiment, linear guide 60 and linear guide 65 may be formed from one continuous member.
Counterweight driver 90 causes counterweight 91 held by a mover to make reciprocating linear motion in the direction of straight line L by means of magnetic circuitry 95. In other words, counterweight driver 90 is implemented by a linear motor.
A specific configuration of lens driver 80 and counterweight driver 90 each implemented by the linear motor will be described later. Lens driver 80 and counterweight driver 90 are also simply collectively referred to as a “linear motor” below. Each of lens driver 80 and counterweight driver 90 is controlled by control device 40. Control device 40 can be a “lens controller” and a “counterweight controller.” Though lens driver 80 and counterweight driver 90 are controlled by control device 40 in common in the embodiment, lens driver 80 and counterweight driver 90 may be controlled by control devices different from each other.
When lens driver 80 causes lens 81 to make reciprocating linear motion in the direction of straight line L which defines an optical axis, counterweight driver 90 causes counterweight 91 to make reciprocating linear motion in a direction opposite to reciprocating motion of lens 81 by a distance as long as the distance of reciprocating linear motion of lens 81. For example, when lens 81 moves along straight line L by 10 mm in a direction toward object 99, counterweight 91 moves along straight line L by 10 mm in a direction away from object 99. When lens 81 moves along straight line L by 15 mm in the direction away from object 99, counterweight 91 moves along straight line L by 15 mm in the direction toward object 99.
As counterweight 91 thus makes reciprocating linear motion in the direction opposite to reciprocating motion of lens 81 by the distance as long as the distance of reciprocating linear motion of lens 81, imbalance in center of gravity of handpiece 70 due to reciprocating linear motion of lens 81 can be canceled. Counterweight 91 can thus cancel vibration caused by reciprocating linear motion of lens 81.
As shown in
Specifically, as shown in
More specifically, the plurality of linear guides 60a and 60b are arranged in parallel to each other at positions in rotation symmetry, with the optical axis (straight line L) that is in parallel to the direction of linear motion of lens 81 and passes through the center of lens 81 being defined as a rotation axis. For example, when each of the plurality of linear guides 60a and 60b is turned by 180 degrees with straight line L being defined as the rotation axis in
Block 56a of linear guide 60a supports lens 81 and is fitted to rail 57a, and causes lens 81 to make reciprocating linear motion by moving in the linear direction along rail 57a. Block 56b of linear guide 60b supports lens 81 at a position different from block 56a and is fitted to rail 57b, and causes lens 81 to make reciprocating linear motion by moving in the linear direction along rail 57b. Linear guides 60a and 60b correspond to linear guide 60 described with reference to
Furthermore, as shown in
Spring 55a and spring 55b have one ends abutting on lens 81 and the other ends fixed in housing 77. Furthermore, spring 55a and spring 55b are held in housing 77 such that deformation thereof in an X direction is permitted and they are less likely to deform in a Y-Z direction. Spring 55a and spring 55b thus arranged apply elastic force to lens 81 in the direction of linear motion. Spring 55a and spring 55b may substantially be equal in diameter to lens 81 so as to be able to fix lens 81 by sandwiching the same therebetween.
On an outer side (a side away from the center of lens 81 in a Z direction) of spring 55a and spring 55b, magnetic circuitry 85a for reciprocating linear motion of lens 81 in the direction of straight line L is provided. Magnetic circuitry 85a includes a magnet 53a composed of the N pole and the S pole and a coil 52a arranged on the outer side (the side away from the center of lens 81 in the Z direction) of magnet 53a.
Magnet 53a is a mover that can be moved in the direction of straight line L. As magnet 53a makes reciprocating linear motion in the X direction along straight line L, lens 81 can also make reciprocating linear motion in the X direction along straight line L. Coil 52a is a stator.
A yoke 51a is provided on the further outer side (the side away from the center of lens 81 in the Z direction) of coil 52a. Yoke 51a is a stator similarly to coil 52a.
On a side opposite to magnetic circuitry 85a with lens 81 being interposed, magnetic circuitry 85b for reciprocating linear motion of lens 81 in the direction of straight line L is provided. Magnetic circuitry 85b includes a magnet 53b composed of the N pole and the S pole and a coil 52b arranged on the outer side (the side away from the center of lens 81 in the Z direction) of magnet 53b.
Magnet 53b is a mover that can be moved in the direction of straight line L. As magnet 53b makes reciprocating linear motion in the X direction along straight line L, lens 81 can also make reciprocating linear motion in the X direction along straight line L. Coil 52b is a stator.
A yoke 51b is provided on the further outer side of coil 52b. Yoke 51b is a stator similarly to coil 52b. Furthermore, yoke 51a and yoke 51b which are stators are fixed as appropriate to housing 77 of handpiece 70.
In lens driver 80 configured as such, as magnetic circuitry 85a and magnetic circuitry 85b apply force to lens 81 in the direction of straight line L, lens 81 makes reciprocating linear motion.
For example, when magnet 53a and magnet 53b each composed of the N pole and the S pole are arranged in positional relation as shown in
Lens 81 vibrates in the direction of straight line L as a result of response by the kinetic system, such as inertial force of lens 81, electromagnetic force (F), elastic force of springs 55a and 55b, and viscous force of the damper. Using this vibration, control device 40 causes lens 81 to make reciprocating linear motion in the direction of straight line L. In other words, control device 40 controls lens driver 80 in constant cycles in accordance with a natural frequency of the kinetic system to feed the drive current to magnetic circuitry 85a and magnetic circuitry 85b, so that lens 81 can make reciprocating linear motion in the direction of straight line L based on a phenomenon of resonance by the kinetic system. Since the drive current is in proportion to an amount of displacement in reciprocating linear motion of lens 81, control device 40 can vary the amount of displacement in reciprocating linear motion of lens 81 by varying the drive current. For example, as control device 40 increases the drive current, the amount of displacement in reciprocating linear motion of lens 81 can increase, and as control device 40 decreases the drive current, the amount of displacement in reciprocating linear motion of lens 81 can decrease.
As the drive current is thus fed to coil 52a and coil 52b in accordance with the natural frequency of the kinetic system, lens driver 80 can function as a resonant drive motor that drives lens 81 to move back and forth in the direction of straight line L. In an example where lens 81 is caused to make reciprocating linear motion by a mechanical arrangement in which a mechanical component such as a cam is connected to a motor, the motor should constantly be kept driven while lens 81 is moved. By using the phenomenon of resonance of the kinetic system as in the embodiment, on the other hand, lens 81 can be caused to make reciprocating linear motion simply by feed of the drive current in magnetic circuitry 85a and magnetic circuitry 85b in constant cycles. Therefore, use of magnetic circuitry 85 as in the embodiment can achieve suppression of power consumption and efficiency. Furthermore, in the case of a cam mechanism, contact noise may be generated by the cam mechanism, or powders resulting from contact may be produced from a cam surface due to deterioration of a cam mechanism portion. By using the phenomenon of resonance of the kinetic system as in the embodiment, such a disadvantage can also be overcome.
As described previously, when lens driver 80 causes lens 81 to make reciprocating linear motion in the direction of straight line L, counterweight driver 90 causes counterweight 91 to make reciprocating linear motion in the direction opposite to reciprocating motion of lens 81 by the distance the same as the distance of motion of lens 81. Lens 81 makes reciprocating linear motion along straight line L, whereas counterweight 91 makes reciprocating linear motion along straight line L in the direction opposite to reciprocating motion of the direction of linear motion of lens 81 in order to cancel imbalance of the center of gravity. The user thus does not feel vibration even when the user uses handpiece 70 by holding the same in his/her hand.
As described above, three-dimensional scanner 100 is configured to vary a focal position of light that passes through lens 81 by causing lens 81 contained in handpiece 70 to make reciprocating linear motion and to take an image of object 99 present at the focal position of light. The focal position of light that passes through lens 81 is dependent on a range of movement of lens 81 that makes reciprocating linear motion.
While three-dimensional scanner 100 is used, handpiece 70 is inclined in various directions and at various angles. Therefore, a component in the direction of reciprocating motion (the direction of straight line L), of gravity applied to lens 81 is varied with variation in angle of inclination of handpiece 70, that is, angle of inclination of lens 81 in handpiece 70. For example, when handpiece 70 is in a horizontal state, the component in the direction of reciprocating motion, of gravity applied to lens 81 is zero. As a tip end of handpiece 70 (a tip end of probe 10) is inclined more in the vertical direction, the component in the direction of reciprocating motion, of gravity applied to lens 81 increases. When the tip end of handpiece 70 (the tip end of probe 10) points to the vertical direction, the entirety of gravity applied to lens 81 defines the component in the direction of reciprocating motion.
When the component in the direction of reciprocating motion, of gravity applied to lens 81 is thus varied with variation in angle of inclination of lens 81, accordingly, a central position of reciprocating motion of lens 81 may also be varied. For example, as the tip end of handpiece 70 is inclined more in the vertical direction, the central position of reciprocating motion of lens 81 moves toward the tip end of handpiece 70. Thus, while three-dimensional scanner 100 is used, the focal position of light that passes through lens 81 moves away from or comes closer to the tip end of handpiece 70 and a depth of field which refers to a range of the focal position may not be stable.
For example,
When handpiece 70 is in the horizontal state, the focal position of lens 81 is more distant from the tip end of handpiece 70 than in the case of inclination of handpiece 70 by 45 degrees. Specifically, since the depth of field when handpiece 70 is in the horizontal state is more distant from the tip end of handpiece 70 than the depth of field in inclination of handpiece 70 by 45 degrees, there may be a gap between the tip end of handpiece 70 and the depth of field. Therefore, when handpiece 70 is in the horizontal state, the user should scan the surface geometry of object 99 by setting the tip end of handpiece 70 to be more distant from object 99 than in inclination of handpiece 70 by 45 degrees (reference state) in order to set the focal position of lens 81 on a portion of the object which is a target of imaging. For example, when handpiece 70 is in the horizontal state, the user should scan the surface geometry of object 99 by holding handpiece 70 such that the tip end thereof is located slightly above object 99, and it is difficult to appropriately move handpiece 70 along object 99.
When handpiece 70 is inclined in the vertical direction, the focal position of lens 81 comes closer to the tip end of handpiece 70 than in inclination of handpiece 70 by 45 degrees. Specifically, since the depth of field when handpiece 70 is inclined in the vertical direction is closer to the tip end of handpiece 70 than the depth of field in inclination of handpiece 70 by 45 degrees, a part of object 99 (for example, a lower portion of object 99) which is a target of imaging by the user may not be included in the depth of field. Therefore, when handpiece 70 is inclined in the vertical direction, the user should scan the surface geometry of object 99 by bringing the tip end of handpiece 70 closer to object 99 than in inclination of handpiece 70 by 45 degrees (reference state) in order to set the focal position of lens 81 on the portion of the object which is the target of imaging. If handpiece 70 is inclined in the vertical direction while the user is scanning the object with handpiece 70 being inclined by 45 degrees (reference state) and with the tip end of handpiece 70 being in contact with object 99, the tip end of handpiece 70 cannot be brought closer to object 99 any more, and hence an image of the surface geometry of a part of object 99 (for example, the lower portion of object 99) cannot be taken.
The user thus has to bring handpiece 70 closer to object 99 or move handpiece 70 away from the object in accordance with the angle of inclination of handpiece 70 in order to set the focal position of lens 81 on the portion of object 99 which is the target of imaging. Depending on the skills of the user, three-dimensional data of the surface geometry of object 99 may not appropriately be obtained. As described below, three-dimensional scanner 100 according to the embodiment is configured to control an operation of lens 81 in accordance with variation in angle of inclination of handpiece 70, that is, angle of inclination of lens 81, to set the focal position of lens 81 on object 99 regardless of the angle of inclination of lens 81.
Detection of variation in angle of inclination of lens 81 by control device 40 will be described with reference to
Movement portion 82B is supported at opposing ends by spring 55a and spring 55b, together with lens 81. When lens 81 is in the horizontal state, index portion 82b of movement portion 82B makes reciprocating motion together with lens 81, with a predetermined encoder reference position being defined as the center. When lens 81 is inclined from the horizontal state, the component in the direction of reciprocating motion, of gravity applied to lens 81 is varied, which moves the central position of reciprocating motion of index portion 82b away from the encoder reference position.
Detector 82A detects a distance (an amount of displacement of lens 81) by which the central position of reciprocating motion of index portion 82b has moved away from the encoder reference position, with scale portion 82a serving as a lead. Control device 40 can detect variation in angle of inclination of lens 81 with respect to the prescribed direction by obtaining a detection value of scale portion 82a and converting the obtained detection value to the angle of inclination of lens 81 with respect to the prescribed direction.
The “angle detector” may be implemented by an absolute encoder or a motion sensor such as a geomagnetic sensor, a gyro sensor, or an acceleration sensor, without being limited to the incremental encoder.
Reciprocating motion of lens 81 with handpiece 70 being in the reference state will be described with reference to
For example, as shown in
During reciprocating motion of lens 81 as described above, encoder 82 detects index portion 82b being located at the encoder reference position and detects variation in angle of inclination of lens 81 with respect to the prescribed direction. In the example in
Reciprocating motion of lens 81 when handpiece 70 is inclined in the vertical direction from the reference state will be described with reference to
For example, as shown in
During reciprocating motion of lens 81 as described above, encoder 82 detects index portion 82b being located at the encoder reference position and detects variation in angle of inclination of lens 81 with respect to the prescribed direction. In the example in
[Control of Operation of Lens in Accordance with Angle of Inclination]
Control of lens 81 in accordance with the angle of inclination of lens 81 with respect to the prescribed direction will be described with reference to
As exemplified in
At t41, lens 81 moves in the first direction (to the right on the sheet plane) from the central position of reciprocating motion. At t42, lens 81 passes through the encoder reference position, and at t43, lens 81 moves in the first direction (to the right on the sheet plane) to the maximum. At this time, the amount of displacement of lens 81 after amplitude control is larger than the amount of displacement of lens 81 before amplitude control. Thereafter, owing to elastic force of spring 55a, lens 81 returns in the second direction (to the left on the sheet plane). At t44, lens 81 passes through the encoder reference position, further at t45, lens 81 passes through the central position of reciprocating motion, and at t46, lens 81 moves in the second direction (to the left on the sheet plane) to the maximum. At this time, the amount of displacement of lens 81 after amplitude control is larger than the amount of displacement of lens 81 before amplitude control. Thereafter, owing to elastic force of spring 55b, lens 81 returns in the first direction (to the right on the sheet plane). At t47, lens 81 passes through the central position of reciprocating motion, further at t48, lens 81 passes through the encoder reference position, and at t49, lens 81 moves in the first direction (to the right on the sheet plane) to the maximum. At this time, the amount of displacement of lens 81 after amplitude control is larger than the amount of displacement of lens 81 before amplitude control. Thereafter, owing to elastic force of spring 55a, lens 81 returns in the second direction (to the left on the sheet plane). At t50, lens 81 passes through the encoder reference position, and at t51, lens 81 returns to the central position of reciprocating motion.
As shown in
[Control of Frame Rate in Accordance with Angle of Inclination]
Control of a frame rate in accordance with the angle of inclination of lens 81 will be described with reference to
As described above, control device 40 increases the amount of displacement in reciprocating linear motion of lens 81 by carrying out amplitude control in accordance with the angle of inclination of lens 81. With increase in amount of displacement of lens 81, a range of imaging by optical sensor 71 becomes wider. Then, in order to ensure accuracy in measurement after amplitude control as high as that before amplitude control, control device 40 controls optical sensor 71 such that a frame rate thereof is higher than before amplitude control.
For example, when handpiece 70 is in the horizontal state or inclined in the vertical direction as shown in
Since three-dimensional scanner 100 can thus take an image of object 99 at a resolution as high as that before amplitude control even when the depth of field is made larger by increasing the amplitude of lens 81 in amplitude control, accuracy in measurement as high as that before amplitude control can be ensured.
As shown in
When the angle of inclination of lens 81 has not varied (NO in S2), control device 40 quits the present process flow. When the angle of inclination of lens 81 has varied (YES in S2), on the other hand, control device 40 changes the amplitude of lens 81 in reciprocating linear motion by varying the drive current to be supplied to magnetic circuitry 85 in accordance with the angle of inclination of lens 81 (S3). For example, control device 40 increases the amplitude of lens 81 in reciprocating linear motion by increasing the drive current to be supplied to magnetic circuitry 85 in accordance with the angle of inclination of lens 81 as shown in
When control device 40 changes the amplitude of lens 81 in reciprocating linear motion, it controls optical sensor 71 to change the frame rate (S4). For example, as shown in
As set forth above, since three-dimensional scanner 100 according to the embodiment can detect variation in angle of inclination of lens 81 and control the operation of lens 81 in accordance with detected variation in angle of inclination to set the focal position of lens 81 on object 99 regardless of the angle of inclination of lens 81, it can appropriately obtain three-dimensional data of the surface geometry of object 99.
When the depth of field is made larger regardless of the angle of inclination of lens 81, the drive current becomes greater even when the depth of field is appropriate as in the reference state. Therefore, the drive current is uselessly consumed and an amount of heat generation also increases. Since the depth of field is large even in the reference state, an image of an unnecessary portion which is not a target of imaging may be taken, computing load for erasure of the unnecessary portion is imposed, and accordingly a computing speed is lowered and the amount of heat generation also increases. In three-dimensional scanner 100 according to the embodiment, however, the depth of field is varied with variation in angle of inclination of lens 81. Therefore, in the reference state, the drive current is not uselessly consumed and an image of an unnecessary portion which is not a target of imaging is not taken either.
The present disclosure is not limited to the embodiment above, but can variously be modified and applied. A modification applicable to the present disclosure will be described below. Only a difference of three-dimensional scanner 100 according to the modification from three-dimensional scanner 100 according to the embodiment will be described, and a component identical to that of three-dimensional scanner 100 according to the embodiment has the same reference character allotted and description thereof will not be repeated.
In three-dimensional scanner 100 according to the embodiment, control device 40 controls the drive current in accordance with variation in angle of inclination of lens 81 to change the amplitude of reciprocating motion of lens 81. Three-dimensional scanner 100 according to the modification may include a mechanism (structure) that changes a central position of reciprocating motion of lens 81 with variation in angle of inclination of lens 81. More specifically, three-dimensional scanner 100 according to the modification may include a mechanism that sets, with variation in angle of inclination of lens 81, the central position of reciprocating motion of lens 81 back to a position before variation in angle of inclination of lens 81.
Lens 81 is thus moved in the downward direction of inclination by “X=mg sine/k” in accordance with the angle of inclination of lens 81. As shown in
Movement mechanism 200 includes linear sliders 201 and 202, a disc 230, links 211 and 212, a spring 220, a support portion 240, and a balance weight 250. Linear slider 201 movably supports lens driver 80. Linear slider 202 movably supports counterweight driver 90. Link 211 connects lens driver 80 and disc 230 to each other. In this example, disc 230 rotates counterclockwise with movement of link 211 in the downward direction of inclination. Link 212 connects counterweight driver 90 and disc 230 to each other. In this example, disc 230 rotates clockwise with movement of link 212 in the downward direction of inclination. Balance weight 250 is connected to disc 230 with support portion 240 being interposed.
According to movement mechanism 200 configured as described above, regardless of the angle of inclination of handpiece 70, lens driver 80 and counterweight driver 90 are balanced with each other owing to links 211 and 212 and disc 230. Since equivalent force is applied to lens driver 80 and counterweight driver 90 by spring 220 in directions opposite to each other, positional relation between lens driver 80 and counterweight driver 90 is stabilized even when handpiece 70 is in the horizontal state.
Since lens 81 is moved in the downward direction of inclination by “X=mg sin θ/k” in the inside of lens driver 80, lens 81 should be moved in the upward direction of inclination. In this connection, owing to the weight of balance weight 250 connected to disc 230 with support portion 240 being interposed, disc 230 rotates clockwise, so that lens driver 80 moves in the upward direction of inclination by “X=mg sin θ/k” together with lens 81.
Since three-dimensional scanner 100 according to the modification can thus move lens 81 in the upward direction of inclination by “X=mg sine/k” with variation in angle of inclination of lens 81, the central position of reciprocating motion of lens 81 can be set back to the position before variation in angle of inclination of lens 81.
A camera for medical use that takes a picture of the inside of the mouth cavity or the inside of the outer ear or the digestive system such as the stomach or the intestines may be applicable as a medical care apparatus to which three-dimensional scanner 100 is applied. In this case, a lens of the camera may be applicable as an object to be held by a mover of the linear motor and a counterweight may be applicable as another mover.
A microscope may be applicable as a medical care apparatus to which three-dimensional scanner 100 is applied. In this case, a lens in the microscope may be applicable as an object to be held by a mover of the linear motor and a counterweight may be applicable as another mover.
Furthermore, a laser pointer that points an object such as a diagram with laser beams or a laser apparatus that cuts a tooth may be applicable as a medical care apparatus to which three-dimensional scanner 100 is applied. In this case, a lens may be applicable as an object to be held by a mover of the linear motor and a counterweight may be applicable as another mover.
It should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present disclosure is defined by the terms of the claims rather than the description above and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. Features exemplified in the embodiment and features exemplified in the modification can be combined as appropriate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-085376 | May 2023 | JP | national |
