Three-dimensional scanner

Abstract

To provide a three-dimensional scanner capable of reducing ghost to be generated due to influence of light scattered on an inner surface of a housing.SOLUTION: A three-dimensional scanner 100 acquires three-dimensional shape information of an object. The three-dimensional scanner 100 comprises: a light source 1 for emitting light to the object; an optical sensor 4 for detecting light from the light source 1 reflected against the object; optical components arranged between the object, and the light source 1 and the optical sensor 4; and a housing 10 for including the light source 1, the optical sensor 4, and the optical components. The housing 10 has a continuously uneven shape in at least a part of an inner surface on an optical path from the optical components to the object.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a three-dimensional scanner for acquiring three-dimensional shape information of an object. [Background technology]

[0002] In recent years, in the field of dentistry, it has become necessary to obtain three-dimensional shape information of teeth in order to digitally design prostheses and the like on a computer, and three-dimensional scanners (intraoral scanners) have been put to practical use (Patent Document 1). The three-dimensional scanner disclosed in Patent Document 1 is configured to insert its tip into the oral cavity, and capture light from the tip into a housing to capture an image of the oral cavity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5654583 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in order to capture images of the inside of the mouth using a three-dimensional scanner, a long optical path must be created from the optical components mounted in the housing to the target object, and there was a risk that light images known as ghosts would appear in the captured image due to light scattered by the inner surface of the housing along the optical path.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a three-dimensional scanner that can reduce ghosts caused by light scattered on the inner surface of the housing. [Means for solving the problem]

[0006] The three-dimensional scanner according to the present disclosure is a three-dimensional scanner that acquires three-dimensional shape information of an object. The three-dimensional scanner includes a light source that emits light to the object, a sensor that detects the light from the light source reflected by the object, optical components provided between the object and the light source and the sensor, and a housing that contains the light source, the sensor, and the optical components. The housing has a continuous uneven shape on at least a part of the inner surface on the optical path from the optical components to the object. Effect of the Invention

[0007] The three-dimensional scanner of the present disclosure has a continuous uneven shape on at least a portion of the inner surface on the optical path from the optical components to the target object, thereby reducing ghosts caused by light scattered on the inner surface of the housing. [Brief description of the drawings]

[0008] [Figure 1] 2 is a schematic diagram for explaining an optical configuration within a housing of a three-dimensional scanner according to an embodiment. FIG. [Diagram 2] 2 is a schematic diagram for explaining the configuration of a tip portion of a three-dimensional scanner according to an embodiment. FIG. [Diagram 3] 1 is a schematic diagram of a three-dimensional scanner having an uneven surface on the inner surface of the housing. [Figure 4] 1 is a cross-sectional view of a portion of a three-dimensional scanner housing having an inner surface with a concave-convex shape. [Diagram 5] 13A to 13C are diagrams for explaining an example of a simulation result of a three-dimensional scanner in which an uneven shape is machined on the inner surface of the housing. [Figure 6] 13A to 13C are diagrams for explaining the simulation results of a three-dimensional scanner in which the inner surface of the housing is not machined to have an uneven shape. [Figure 7] 13A to 13C are diagrams for explaining the results of a simulation of a three-dimensional scanner when the uneven shape machined on the inner surface of the housing is changed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] (Embodiment) The three-dimensional scanner according to the embodiment is a three-dimensional scanner (intraoral scanner) for acquiring three-dimensional shape information of intraoral tissues (e.g., teeth). The intraoral scanner may acquire three-dimensional shape information of not only intraoral teeth but also gums, mucous membranes, dental prostheses, scan bodies for implants, orthodontic devices, various dental prostheses, etc. In addition, the three-dimensional scanner is not limited to an intraoral scanner, and may be applied to other three-dimensional scanners having a similar configuration. For example, the present invention may be applied to a three-dimensional scanner that can acquire three-dimensional shape information of the inside of a human ear by imaging the inside of a human ear in addition to the inside of the oral cavity.

[0011] [Configuration of 3D scanner] Fig. 1 is a schematic diagram for explaining the optical configuration within the housing 10 of the three-dimensional scanner 100 according to the embodiment. Fig. 1 illustrates the optical configuration within the housing 10 of the three-dimensional scanner 100 for imaging the oral cavity, but does not illustrate the configuration of a calculation circuit that processes and displays the acquired data. In addition, the three-dimensional scanner 100 may calculate the three-dimensional shape of the oral cavity from the captured image within the housing 10, or may calculate it using a computer (not shown) connected to the housing 10.

[0012] The housing 10 will be described below as an optical configuration that acquires a three-dimensional shape using the principles of focusing, but is not limited to this optical configuration and may be an optical configuration that acquires a three-dimensional shape using principles such as confocal focusing, triangulation, white light interferometry, stereo, photogrammetry, Simultaneous Localization and Mapping (SLAM), and Optical Coherence Tomography (OCT).

[0013] 1, the housing 10 includes a light source 1, a light source lens 2, a pattern generating unit 3, an optical sensor 4, a beam splitter 5, a focus variable lens 6, a focus position detecting unit 7, a lens 8, and a mirror 9. In addition to the above, the housing 10 may be provided with other optical components such as another lens, an aperture, an optical filter, a window, and a polarizing element, as necessary.

[0014] The light source 1 is, for example, an LED (Light Emitting Diode). The light source 1 can change the amount of light emitted. For example, in the case of an LED, the amount of light emitted can be adjusted by changing the amount of current supplied to the LED from a driver circuit (not shown). The light source 1 is not limited to a point light source having one LED or laser element, but may be an array light source having a plurality of element light sources such as LEDs or laser elements arranged on a substrate. A multi-color light source such as a three-primary color LED may also be used.

[0015] The light source lens 2 uniformly emits light from the light source 1 and irradiates it onto the pattern generating unit 3. The pattern generating unit 3 is a filter having a pattern such as a line or checkered pattern, and generates a pattern to be projected onto the surface of the object. The object is, for example, intraoral tissue, and the three-dimensional scanner 100 is used inside the oral cavity.

[0016] The optical sensor 4 is, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor. The optical sensor 4 detects light that passes through the pattern generating unit 3, is projected onto the object, and is reflected by the object. The beam splitter 5 is an optical component that separates an optical path from the light source 1 to the object and an optical path from the object to the optical sensor 4.

[0017] The variable-focus lens 6 has a focusing lens 6a fixed to a slider, and the slider moves on a rail (not shown) extending in the optical axis direction to change the focal position on the target object and the focal position on the optical sensor 4. Specifically, the variable-focus lens 6 drives a motor by a drive signal supplied from a motor driver (not shown) to reciprocate the focusing lens 6a fixed to the slider within the range indicated by the arrow. The variable-focus lens 6 changes the position of the focusing lens 6a from a focal position Z close to the output end surface of the housing 10 to a focal position Z far from the output end surface.

[0018] The focal position detection unit 7 detects the focal position of the variable focus lens 6. The focal position detection unit 7 does not directly detect the focal position Z, but indirectly detects the focal position Z by detecting the position of the focus lens 6a corresponding to the focal position Z. Specifically, the focal position detection unit 7 is an optical encoder (lens position sensor) that detects the position of the focus lens 6a. Note that the focal position detection unit 7 may be a detector other than an optical encoder as long as it can detect the position of the focus lens 6a. For example, position detection using a magnetic sensor may be applied.

[0019] The light that has passed through the variable focus lens 6 passes through the lens 8 and the mirror 9 and is irradiated onto the object. The lens 8 is an optical component that focuses the light that has passed through the variable focus lens 6 onto the object. The mirror 9 is an optical component that changes the direction of the light from the light source 1 and the light reflected by the object. The configurations of the lens 8 and the mirror 9 are merely examples, and the configurations can be changed as necessary.

[0020] In FIG. 1, the tip of the three-dimensional scanner 100 inserted into the oral cavity is illustrated as being integrated with the housing 10, but may be detachable from the housing 10. FIG. 2 is a schematic diagram for explaining the configuration of the tip of the three-dimensional scanner 100 according to the embodiment. In FIG. 2, a tip 12 (also called a cap or a probe) is detachable from the tip of the three-dimensional scanner 100. The tip 12 is a part that comes into contact with the living body, and can be removed from the housing 10 and sterilized (for example, in a high-temperature, high-humidity environment) as a countermeasure against infection. If the entire device of the three-dimensional scanner is sterilized, there is a drawback that the life of the device is shortened because it contains many optical components and electronic components, but if only the tip 12 is removed and sterilized, this drawback does not occur.

[0021] The part of the housing 10 to which the chip 12 is attached is a cylindrical part 11 that has a cylindrical shape that can be fitted with the chip 12 and protrudes from the housing 10. The cylindrical part 11 may have optical components such as a lens system for guiding the light collected by the chip 12 to the optical sensor 4 in the housing 10, a cover glass, an optical filter, and a retardation plate (1 / 4 wavelength plate). On the other hand, the chip 12 is provided with a mirror 9 and an opening 12a on the optical path since it is subjected to a sterilization treatment. Of course, the chip 12 may be provided with optical components that are sufficiently resistant to the sterilization treatment.

[0022] [Inner shape of the housing] Next, the shape of the inner surface of the housing 10 of the three-dimensional scanner 100 will be described. In the three-dimensional scanner 100, light from the light source 1 is irradiated onto the pattern generating unit 3, and the pattern of the pattern generating unit 3 is projected onto the surface of the object. Furthermore, in the three-dimensional scanner 100, the light projected onto the object and reflected by the object is detected by the optical sensor 4. Therefore, the light from the light source 1 or the light reflected by the object may be scattered on the inner surface of the housing 10, causing an image of the light called a ghost to appear in the captured image.

[0023] Therefore, in the three-dimensional scanner 100 according to the present embodiment, in order to reduce ghosts, a continuous uneven shape is provided on at least a part of the inner surface of the housing 10 on the optical path from the optical components to the object. FIG. 3 is a schematic diagram of the three-dimensional scanner 100 in which the uneven shape 13 is processed on the inner surface of the housing 10. FIG. 4 is a cross-sectional view of a part in which the uneven shape 13 is processed on the inner surface of the housing 10 of the three-dimensional scanner 100. In FIG. 1, for the sake of simplicity, only the focusing lens 6a and the lens 8 are shown as the configuration of the optical components in the direction from the beam splitter 5 to the object. FIG. 3 shows the optical configuration of the three-dimensional scanner 100 in more detail. As shown in FIG. 3, the three-dimensional scanner 100 has six lenses between the beam splitter 5 and the retardation plate 70.

[0024] The six lenses, from the side closest to the beam splitter 5, are a first lens 61, a second lens 62, a third lens 63, a fourth lens 64, a fifth lens 65, and a sixth lens 66. The second lens 62 corresponds to the focusing lens 6a, and at least one of the third lens 63 to the sixth lens 66 corresponds to the lens 8.

[0025] In one example of a three-dimensional scanner 100 shown in Fig. 3, a continuous uneven shape 13 is processed on a part of the inner surface of the tube portion 11 between the fourth lens 64 and the fifth lens 65. Although Fig. 3 only illustrates the uneven shape 13 on the cross section of the tube portion 11, the uneven shape 13 is processed on the entire inner surface of the tube portion 11 between the fourth lens 64 and the fifth lens 65. In other words, the uneven shape 13 is also processed in the circumferential direction of the inner surface of the tube portion 11 shown in Fig. 3. Hereinafter, even if the uneven shape 13 is processed on the entire circumferential direction of the inner surface of the tube portion 11, it will be simply described as the uneven shape 13 being processed on the inner surface of the tube portion 11. Furthermore, the portion of the inner surface on which the uneven shape 13 is machined is not limited to the inner surface of the housing 10 between the fourth lens (fourth lens 64) and the fifth lens (fifth lens 65) counting from the light source 1, but may be at least a part of the inner surface of the housing 10 on the optical path from the beam splitter 5, which is an optical component, to the object, and it is particularly preferable that it be at least a part of the inner surface of the tube portion 11.

[0026] The uneven shape 13 machined on the inner surface of the housing 10 preferably has a wavy cross-sectional shape in the longitudinal direction (parallel to the optical path) of the housing 10. Specifically, the cross-sectional shape of the uneven shape 13 has a shape with a wavy period (a) and a wavy amplitude (b), for example a sine curve, as shown in Fig. 4. Note that the uneven shape 13 is not limited to a wavy shape, and may be any shape that can reduce ghosting, such as a spiral shape, a threaded shape, a shape with multiple small peaks, or a shape like one surface of a sponge.

[0027] Furthermore, the uneven shape 13 will be described in detail using simulation results. FIG. 5 is a diagram for explaining an example of a simulation result of a three-dimensional scanner 100 in which the uneven shape 13 is processed on the inner surface of the housing 10. FIG. 5(a) is a simulation result of an image obtained by the optical sensor 4 when the uneven shape 13 is processed on the inner surface of the housing 10. FIG. 5(b) is a diagram showing the light intensity on the line I (Y direction) in FIG. 5(a). FIG. 5 shows a simulation result of a three-dimensional scanner 100 having an uneven shape 13 in which the absolute value (|a / b|) of the ratio of the wave period (a) to the wave amplitude (b) is 13.3.

[0028] On the other hand, Fig. 6 is a diagram for explaining the simulation results of a three-dimensional scanner in which the uneven shape 13 is not machined on the inner surface of the housing 10. Fig. 6(a) shows the simulation results of an image obtained by the optical sensor 4 when the uneven shape 13 is not machined on the inner surface of the housing 10. Fig. 6(b) is a diagram showing the light intensity on line II (Y direction) in Fig. 6(a). As can be seen from Fig. 6(a), when the uneven shape 13 is not machined on the inner surface of the housing 10, a crescent-shaped ghost (stray light) is generated. The maximum light intensity of the ghost is about 1 x 10 as shown in Fig. 6(b). -2 (1E-2) Lumens / mm 2 It is.

[0029] In Fig. 5(a), no ghost like the crescent moon in Fig. 6(a) occurs. Also, the maximum light intensity of the ghost shown in Fig. 5(a) is about 5 × 10 -5(5E-5) Lumens / mm 2 In other words, compared to a three-dimensional scanner in which the uneven shape 13 is not machined on the inner surface of the housing 10, the three-dimensional scanner 100 in which the uneven shape 13 is machined on the inner surface of the housing 10 has a maximum light intensity of ghosts that is reduced to about 1 / 200.

[0030] As a result of simulating the three-dimensional scanner 100 by changing the absolute value (|a / b|) of the ratio of the wave period (a) to the wave amplitude (b) (hereinafter also referred to as the absolute value of the wave ratio (|a / b|)), it was found that the ghost is reduced as the absolute value of the wave ratio (|a / b|) becomes smaller. FIG. 7 is a diagram for explaining the simulation result of the three-dimensional scanner 100 when the uneven shape 13 machined on the inner surface of the housing 10 is changed. The absolute value of the wave ratio (|a / b|) shown in FIG. 7(a) is 280. The maximum light intensity of the ghost shown in FIG. 7(a) is about 5×10 -4 (5E-4) Lumens / mm 2 The maximum light intensity of the ghost shown in FIG. 7(a) is reduced to about 1 / 20 of that of the ghost shown in FIG. 6(a).

[0031] The absolute value of the ratio of the waves shown in FIG. 7(b) (|a / b|) is 140. The maximum light intensity of the ghost shown in FIG. 7(b) is about 1×10 -4 (1E-4) Lumens / mm 2 The maximum light intensity of the ghost shown in Fig. 7(b) is reduced to about 1 / 100 of that of the ghost in Fig. 6(a). In other words, it can be seen that the uneven shape 13 (wave shape) can reduce the ghost to about 1 / 100 if the absolute value (|a / b|) of the ratio of the wave period (a) to the wave amplitude (b) is less than 140.

[0032] Furthermore, the absolute value of the ratio of the waves shown in FIG. 7(c) (|a / b|) is 28. The maximum light intensity of the ghost shown in FIG. 7(c) is about 5×10 -5 (5E-5) Lumens / mm 2The maximum light intensity of the ghost shown in FIG. 7(c) is reduced to about 1 / 2500 of that of the ghost shown in FIG. 6(a). In this way, the smaller the absolute value of the ratio of the waves (|a / b|) of the uneven shape 13 (wave shape), the larger the amplitude (b) of the waves will be if the cycle (a) of the waves is the same, and it is considered that the ghost will be gradually diffused as the unevenness of the waves increases. Also, the ghost can be reduced more as the absolute value of the ratio of the waves (|a / b|) decreases, but the smaller the absolute value of the ratio of the waves (|a / b|) is, the larger the unevenness of the waves will be, making it difficult to process in practice. Therefore, it is practically preferable that the absolute value of the ratio of the waves (|a / b|) of the uneven shape 13 (wave shape) is 13.3 or more.

[0033] [Variations] The uneven shape 13 may be processed uniformly on the inner surface of the housing 10, but it is preferable to process it so that the absolute value (|a / b|) of the ratio of the wave period (a) to the wave amplitude (b) is smaller on the beam splitter 5 side (optical component side) than on the retarder 70 side (object side) shown in Fig. 3. This is because a stronger ghost is generated on the beam splitter 5 side (optical component side) of the tube part 11 than on the retarder 70 side (object side). Note that since the three-dimensional scanner 100 is an elongated optical system having the tube part 11 to capture an image of the oral cavity, stray light reflected near the retarder 70 side (object side) tends to be scattered before reaching the optical sensor 4, or is blocked by various structures, making it difficult for the stray light to reach the optical sensor 4.

[0034] It has been explained that the absolute value (|a / b|) of the proportion of the waves of the uneven shape 13 machined on the inner surface of the tube portion 11 on the beam splitter 5 side (optical component side) is smaller than the absolute value (|a / b|) of the proportion of the waves of the uneven shape 13 machined on the inner surface of the tube portion 11 on the retardation plate 70 side (object side). This is not limited to the case where the absolute value (|a / b|) of the proportion of the waves is different between the two locations, and the absolute value (|a / b|) of the proportion of the waves of the uneven shape 13 machined on the inner surface of the tube portion 11 may decrease stepwise or continuously from the retardation plate 70 side (object side) to the beam splitter 5 side (optical component side).

[0035] If the cross-sectional shape of the uneven shape 13 in the longitudinal direction of the housing 10 is a triangle with a sharp ridge, there is no flat surface for regular reflection, and therefore ghosting is hardly generated. However, since the inner surface of the actual housing 10 has a light-shielding line or a screw groove, it is difficult to process the uneven shape 13 into a triangular cross-sectional shape with a completely sharp ridge. For example, it has been found from the simulation results that a weak ghosting occurs when a flat portion of about 0.05 mm remains in a part of the triangular uneven shape 13. Compared to processing the uneven shape 13 into a triangular cross-sectional shape with a completely sharp ridge, it is easier to process the uneven shape 13 into a corrugated cross-sectional shape, and ghosting can be reduced more stably.

[0036] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0037] 1 light source, 2 light source lens, 3 pattern generation unit, 4 optical sensor, 5 beam splitter, 6 focus variable lens, 6a focus lens, 7 focus position detection unit, 8 lens, 9 mirror, 10 housing, 11 tube part, 12 chip, 13 uneven shape, 70 phase difference plate, 100 three-dimensional scanner.

Claims

1. A three-dimensional scanner for acquiring three-dimensional shape information of an object, A light source that emits light toward the object; a sensor for detecting light from the light source reflected by the object; an optical component provided between the object and the light source and the sensor; a housing that contains the light source, the sensor, and the optical components; A three-dimensional scanner, wherein the housing has a continuous uneven shape on at least a portion of the inner surface on the optical path from the optical component to the object.

2. the housing has a cylindrical portion having a cylindrical shape extending from the vicinity of the optical component to the vicinity of the object, The three-dimensional scanner according to claim 1 , wherein at least a portion of the inner surface of the cylindrical portion has the continuous uneven shape.

3. The three-dimensional scanner of claim 2 , wherein the barrel is capped with a tip having a mirror and an opening in the optical path.

4. The three-dimensional scanner of claim 1 , wherein the optical components include a variable focus lens that changes a focal position relative to the object.

5. The optical component includes a plurality of lenses; The three-dimensional scanner according to claim 4 , wherein the continuous concave-convex shape is provided on an inner surface of the housing between a fourth lens and a fifth lens counting from the light source.

6. The three-dimensional scanner according to any one of claims 1 to 5, wherein the continuous uneven shape is a wave shape in a cross section in the longitudinal direction of the housing.

7. The three-dimensional scanner according to claim 6, wherein the wave shape has an absolute value (|a / b|) of a ratio of a wave period (a) to a wave amplitude (b) of less than 140.

8. The three-dimensional scanner of claim 6, wherein the absolute value (|a / b|) of the ratio of the wave period (a) to the wave amplitude (b) of the wave is smaller on the optical component side than on the object side.

9. The three-dimensional scanner according to any one of claims 1 to 5, wherein the object is an intraoral tissue and is used in the oral cavity.

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