Stereoscopic imaging device for dental treatment and stereoscopic observation system for dental treatment

Abstract

A stereoscopic imaging device (2A) comprises: an imaging unit (21) that has an imaging region divided into left and right regions; a convergence-angle setting unit (10) that sets a convergence angle formed by the left and right imaging regions and an imaging subject; and a display control unit (31A) that controls an image captured by the imaging unit (21). The convergence-angle setting unit (10) sets the convergence angle to more than 0° and no more than 5° for an imaging subject located at a distance of 300-1,000mm from the convergence-angle setting unit.

Description

Stereoscopic imaging device for dental treatment and stereoscopic observation system for dental treatment

[0001] The present invention relates to a technique for imaging a subject in a stereoscopic manner.

[0002] As a technique for imaging a subject with a stereoscopic image, Patent Document 1 describes a stereoscopic photography device in which a stereo adapter is attached to a lens shutter camera. The stereo adapter includes a first reflection mirror and a second reflection mirror. Light from the subject is reflected in sequence by the first reflection mirror and the second reflection mirror and enters the lens shutter camera.

[0003] Japanese Patent Laid-Open No. 7-064216

[0004] In such a stereoscopic photography device, the convergence angle of the subject can be set by changing the posture of the first reflection mirror disposed outward in the left-right direction of the second reflection mirror. However, in this stereoscopic photography device, when the distance to the subject is short, the convergence angle becomes large and the stereoscopic range is narrow.

[0005] In a conventional stereomicroscope, the convergence angle is set to about 12°. For example, when stereoscopically viewing the inside of a tooth root canal in dental treatment, it is difficult to stereoscopically view the deep part of the root canal with such a stereomicroscope with a convergence angle.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to provide a stereoscopic imaging device for dental treatment and a stereoscopic observation system for dental treatment that can suitably image an image that can stereoscopically view the inside of a narrow hole of a subject.

[0007] In order to solve the above problems, the stereoscopic imaging device for dental treatment of the present invention includes an imaging unit having an imaging region divided into left and right, a convergence angle setting unit that sets a convergence angle formed by the left and right imaging regions and the subject, and a display control unit that controls an image captured by the imaging unit. The convergence angle setting unit is characterized in that the convergence angle is set to be greater than 0° and 5° or less with respect to the subject located at a distance of 300 mm to 1000 mm from the convergence angle setting unit.

[0008] According to the present invention, the convergence angle can be set to a small value, making it possible to suitably capture images of narrow openings in a subject, such as the root canal of a tooth, as stereoscopic images.

[0009] This is a schematic block diagram illustrating a stereoscopic observation system according to the first embodiment of the present invention. This is a schematic plan view illustrating the convergence angle setting unit. This is a diagram illustrating an example of an image rearrangement method by the rearrangement unit, where (a) schematically shows an image when the subject is imaged at the focal length, (b) schematically shows an image when the subject is imaged at a distance greater than the focal length, and (c) schematically shows an image when the region and the subject are aligned in the case of (b). This is a diagram illustrating an example of an image rearrangement method by the rearrangement unit, where (a) schematically shows an image when the subject is imaged at the focal length, (b) schematically shows an image when the subject is imaged at a distance greater than the focal length, and (c) schematically shows an image when the region and the subject are aligned in the case of (b). This is a schematic diagram illustrating an example of the offset amount between the center of the subject and the center of the imaging region. This diagram illustrates an example of changing the magnification of an image using a magnification change unit. (a) schematically shows the image and display range when the magnification is relatively small (before magnification change), and (b) schematically shows the image after magnification change. This diagram schematically shows an example of a stereoscopic display device. (a) schematically shows a single device that displays left and right images, and (b) schematically shows two devices that display left and right images, respectively. This is a flowchart for explaining an example of operation of a stereoscopic observation system according to the first embodiment of the present invention. This is a block diagram schematically showing a stereoscopic observation system according to the second embodiment of the present invention. This is a flowchart for explaining an example of operation of a stereoscopic observation system according to the second embodiment of the present invention. This is a block diagram schematically showing a stereoscopic observation system according to the third embodiment of the present invention. This is a plan view schematically showing a convergence angle setting unit. This is a flowchart for explaining an example of operation of a stereoscopic observation system according to the third embodiment of the present invention. This is a block diagram schematically showing a stereoscopic observation system according to the fourth embodiment of the present invention. This is a flowchart for explaining an example of operation of a stereoscopic observation system according to the fourth embodiment of the present invention. This is a plan view schematically showing a stereoscopic display device of a stereoscopic observation system according to the fifth embodiment of the present invention. This is a schematic plan view of a stereoscopic display device for a stereoscopic observation system according to the fifth embodiment of the present invention, and is a diagram for explaining the convergence angle of the displayed virtual image.This is a schematic plan view showing a stereoscopic display device for a stereoscopic observation system according to the sixth embodiment of the present invention.

[0010] Embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted. Directional indications in the drawings indicate the corresponding relationships between the drawings.

[0011] <First Embodiment> As shown in Figure 1, the stereoscopic observation system 1A according to the first embodiment of the present invention is a system (more specifically, a stereoscopic observation system for dental treatment) that images the inside of the root canal of a tooth (see Figure 2), which is a narrow opening 4a of the subject 4, and displays it in a stereoscopic manner. The stereoscopic observation system 1A comprises a stereoscopic imaging device 2A and a stereoscopic display device 3.

[0012] <Stereoscopic Imaging Device> The stereoscopic imaging device 2A comprises a convergence angle setting unit 10, an imaging device 20A, and a control unit 30A. This stereoscopic imaging device 2A is a device (more specifically, a stereoscopic imaging device for dental treatment) that generates a pair of left and right images (stereo images) of a subject 4 that can be viewed in 3D by imaging the subject 4 from different angles with a single imaging device 20A. The stereoscopic imaging device 2A is, for example, a stereoscopic microscope.

[0013] <Convergence Angle Setting Unit> As shown in Figure 2, the convergence angle setting unit 10 sets the convergence angle θ between the imaging areas 20L and 20R, which are divided into left and right sections, and the subject 4. In this embodiment, the convergence angle θ is the angle between the optical component of the convergence angle setting unit that is positioned closest to the subject 4 (in this embodiment, the mirrors 12L and 12R, which will be described later) and the subject 4.

[0014] The convergence angle setting unit 10 comprises an optical system 11 consisting of a left optical system 11L and a right optical system 11R. The optical system 11 includes, as optical components for the left optical system 11L and the right optical system 11R, mirrors 12 (12L, 12R) and prisms 13 (13L, 13R). The optical system 11 also includes a prism 14 as an optical component common to both the left optical system 11L and the right optical system 11R. The convergence angle setting unit 10 enables the shooting of subjects 4 at short distances by realizing the optical system using the mirrors 12, prisms 13 and prisms 14. Furthermore, the mirrors 12 of the convergence angle setting unit 10 can also achieve variability of the convergence angle θ, as in the third and fourth embodiments described later.

[0015] The mirror 12 is positioned between the subject 4 and the prism 14 in the optical axis direction of the imaging device 20A. The mirror 12 has a reflective surface 12a. The reflective surface 12a is the first reflective surface that reflects the light 5 from the subject 4 outward in the left-right direction. In the left optical system 11L, the reflective surface 12a of the mirror 12L reflects the light 5L from the subject 4 to the left. In the right optical system 11R, the reflective surface 12a of the mirror 12R reflects the light 5R from the subject 4 to the right. In Figures 2 and 12, the line drawn as light 5 represents the optical axis of light 5.

[0016] Prism 13 is positioned outward in the left-right direction from mirror 12 and prism 14. Prism 13 comprises an input / output surface 13a, a reflecting surface 13b, and a reflecting surface 13c. Reflecting surface 13b is a second reflecting surface that reflects light 5 incident from reflecting surface 12a through input / output surface 13a toward the imaging device 20A in the optical axis direction. In the left optical system 11L, prism 13L is positioned to the left of mirror 12L and prism 14. Reflecting surface 13b of prism 13L reflects light 5L reflected by reflective surface 12a of mirror 12L toward reflecting surface 13c. In the right optical system 11R, prism 13R is positioned to the right of mirror 12R and prism 14. Reflecting surface 13b of prism 13R reflects light 5R reflected by reflective surface 12a of mirror 12R toward reflecting surface 13c.

[0017] The reflective surface 13c is a third reflective surface that reflects the light 5 from the reflective surface 13b inwards to the left and right. In the left optical system 11L, the reflective surface 13c of the prism 13L reflects the light 5L reflected by the reflective surface 13b of the prism 13L to the right. In the right optical system 11R, the reflective surface 13c of the prism 13R reflects the light 5R reflected by the reflective surface 13b of the prism 13R to the left.

[0018] The prism 14 is positioned between the mirror 12 and the imaging device 20A in the optical axis direction of the imaging device 20A. The prism 14 includes a reflective surface 14a belonging to the left optical system 11L and a reflective surface 14b belonging to the right optical system 11R. The reflective surface 14a is a fourth reflective surface that reflects light 5L from the reflective surface 13c of the prism 13L toward the imaging device 20A in the optical axis direction and incident it onto the left imaging area 20L of the imaging unit 21. The reflective surface 14b is a fourth reflective surface that reflects light 5R from the reflective surface 13c of the prism 13R toward the imaging device 20A in the optical axis direction and incident it onto the right imaging area 20R of the imaging unit 21.

[0019] In this way, the light 5L from the subject 4 is reflected by the left optical system 11L, that is, by the reflective surface 12a of the mirror 12L, the reflective surfaces 13b and 13c of the prism 13L, and the reflective surface 14a of the prism 14, and enters the left imaging area 20L of the imaging device 20A. Similarly, the light 5R from the subject 4 is reflected by the right optical system 11R, that is, by the reflective surface 12a of the mirror 12R, the reflective surfaces 13b and 13c of the prism 13R, and the reflective surface 14b of the prism 14, and enters the right imaging area 20R of the imaging device 20A.

[0020] In this embodiment, the convergence angle setting unit 10 sets the convergence angle θ based on the orientation of the fixed mirrors 12L and 12R. Furthermore, since the mirrors 12L and 12R are positioned narrower in the left-right direction than the reflective surfaces 13c of the prisms 13L and 13R, the convergence angle θ can be set to a small value even when the distance to the subject 4 is short.

[0021] In such a convergence angle setting unit 10, it is desirable to set the convergence angle θ to be greater than 0° and 5° or less at the working distance L. Here, the working distance L is the distance in the optical axis direction of the imaging device 20A between the point where light 5 is reflected on the reflective surface 12a of the mirror 12 and the subject 4. When the subject 4 is a tooth requiring root canal treatment, the working distance L is preferably in the range of a relatively short distance of 300 mm to 1000 mm, more preferably 300 mm to 500 mm. The convergence angle setting unit 10 may also be configured to set the convergence angle θ to be greater than 0° and 5° or less for subjects 4 where the working distance L is greater than 1000 mm.

[0022] Here, we will explain the convergence angle θ when the distance W between the points where light 5 from the subject 4 is reflected on the reflective surfaces 12a of the left and right mirrors 12, that is, the distance W between the point where the optical axis of light 5L is reflected by the reflective surface 12a of mirror 12L and the point where the optical axis of light 5R is reflected by the reflective surface 12a of mirror 12R, is set to 20.0 mm. When the working distance L is 300 mm, the convergence angle θ is approximately 3.78°, and when the working distance L is 400 mm, the convergence angle θ is approximately 2.86°. Furthermore, when the working distance L is 500 mm, the convergence angle θ is approximately 2.29°, and when the working distance L is 1000 mm, the convergence angle θ is approximately 1.15°. In this way, by setting the distance W between the reflective surfaces 12a of the left and right mirrors 12 to a narrow distance (approximately 20.0 mm), the convergence angle θ can be set to greater than 0° and 5° or less within the aforementioned working distance L range, thereby suitably imaging the inside of the tooth root canal, which is the hole 4a of the subject 4, and generating a stereoscopic image. Furthermore, by setting the convergence angle θ to an even smaller value, the displacement m between the subject 4 and the viewpoint from the front of the tooth (subject 4) to the back of the root canal (hole 4a) becomes approximately constant (the difference between the displacement m between the subject 4 and the viewpoint at the front of the tooth and the displacement m between the subject 4 and the viewpoint at the back of the root canal is very small), thus allowing for suitable stereoscopic viewing from the front of the tooth to the back of the root canal. Here, the displacement m between the subject 4 and the viewpoint is the offset amount between the centers of the left and right imaging areas, that is, the centers of the left and right display areas 3L and 3R, and the centers of the left and right subjects 4 imaged in those imaging areas. In Figure 2 and Figure 12 (described later), the displacement m corresponding to one of the left and right optical systems 11 (the left optical system 11L) is shown. The distance W can be set based on the distance to the front of the subject 4 and the convergence angle θ that allows for suitable imaging of the hole 4a of the subject 4.

[0023] As an example of subject 4, the root canal of a tooth is a hole with a diameter of 1 mm or less (approximately 0.5 mm). In order to observe the depths of a root canal with a diameter of 1 mm and a depth of 12 mm, the convergence angle θ needs to be set to approximately 4.8° or less. Also, in order to observe the depths of a root canal with a diameter of 0.5 mm and a depth of 12 mm, the convergence angle θ needs to be set to approximately 2.4° or less. Note that with a conventional stereomicroscope with a convergence angle of 12°, it is only possible to observe a root canal with a diameter of 0.5 mm to a depth of 2.38 mm. Therefore, it is desirable for the convergence angle setting unit 10 to set the convergence angle θ to 5° or less, and more desirable to set the convergence angle θ to 3° or less.

[0024] In other words, the convergence angle setting unit 10 includes a left optical system 11L and a right optical system 11R. Of the left optical system 11L and the right optical system 11R, the distance W between the points where the optical axis of light 5 from the subject 4 is reflected at the reflective surface 12a closest to the subject 4 is set to 20.0 mm. As a result, the convergence angle setting unit 10 can set the convergence angle θ to greater than 0° and less than or equal to 5° in a working distance L range of 300 mm to 1000 mm with a simple configuration. The number and angles of reflective surfaces other than the reflective surface 12a can be changed as appropriate, as long as light 5 from the subject 4 can be captured in the left and right imaging areas of the imaging device 20A via the reflective surface 12a.

[0025] Here, we will explain the working distance L when imaging the inside of the root canal of a tooth, which is the hole 4a of the subject 4, in dental treatment. From the viewpoint of placing hands, treatment instruments, etc., into the patient's oral cavity, it is preferable to secure a space of 300 mm or more between the stereoscopic microscope, which is the stereoscopic imaging device 2A, and the patient's mouth. Furthermore, from the viewpoint of the operability of treatment instruments, etc., in the oral cavity, it is preferable to set the distance between the stereoscopic microscope, which is the stereoscopic imaging device 2A, and the patient's mouth to 1000 mm or less, more preferably 500 mm or less.

[0026] <Imaging device> As shown in Figure 1, the imaging device 20A comprises an imaging unit 21 and an imaging control unit 22A.

[0027] <Imaging Unit> The imaging unit 21 comprises a control board 21a, an image sensor 21b, an optical system 21c, and an optical system drive unit 21d.

[0028] ≪Control Board≫ The control board 21a comprises an electronic circuit consisting of multiple electronic components mounted on the board. The control board 21a is electrically connected to the image sensor 21b, the optical system drive unit 21d, and the image control unit 22A. The control board 21a outputs electrical signals from the image sensor 21b to the image control unit 22A. The control board 21a also controls the optical system drive unit 21d based on control signals from the image control unit 22A.

[0029] ≪Image Sensor≫ The image sensor 21b forms an image of light from the subject 4, converts the formed light into an electrical signal (digital signal), and outputs the converted electrical signal to the control board 21a. The image sensor 21b has an imaging area divided into left and right sections. Here, the left and right divided imaging area refers to dividing the planar image sensor 21b into a left imaging area and a right imaging area by dividing it in the middle in the left-right direction, and does not refer to two planar image sensors placed spaced apart on the left and right. The left and right imaging areas are set to correspond to the left and right optical systems 11 of the convergence angle setting unit 10, respectively.

[0030] <<Optical System>> The optical system 21c is a group of optical components (lenses, etc.) located in front of the image sensor 21b.

[0031] <<Optical System Drive Unit>> The optical system drive unit 21d is composed of a motor and the like, and changes the focal position by driving the optical system 21c. The optical system drive unit 21d outputs the focus position value, which is the position information of the optical components of the optical system 21c, to the distance measuring unit 22b as a value related to the focal position.

[0032] <Image Control Unit> The image control unit 22A is composed of a CPU (Central Processing Unit), ROM (Read-Only Memory), RAM (Random Access Memory), input / output circuits, etc. The image control unit 22A includes a focus changing unit 22a and a distance measuring unit 22b as functional units.

[0033] <Focus Change Unit> The focus change unit 22a drives the optical system 21c by controlling the optical system drive unit 21d via the control board 21a, thereby changing the focal position (focus function).

[0034] <Distance Measurement Unit> The distance measurement unit 22b measures the distance from the image sensor 21b to the subject 4, and / or the distance from the mirror 12 to the subject 4, and outputs the measured distance to the control unit 30A. The distance measurement unit 22b measures the length of the optical path of the light 5 reflected by the convergence angle setting unit 10 as the distance from the image sensor 21b or the distance sensor 22b to the subject 4.

[0035] <Control Unit> The control unit 30A is composed of a CPU, ROM, RAM, input / output circuits, etc. The control unit 30A includes a display control unit 31A as a functional unit.

[0036] <Display Control Unit> The display control unit 31A controls the display content of the image of the subject 4 captured by the imaging unit 21 on the stereoscopic display device 3, and includes a rearrangement unit 31a and a magnification changing unit 31b.

[0037] <Repositioning Unit> The repositioning unit 31a moves the display ranges 6L and 6R based on the measurement results of the distance measuring unit 22b and a preset convergence angle θ, and repositions (aligns) the image of the subject 4 to the center of the display areas 3L and 3R. In the convergence angle setting unit 10 of this embodiment, since the convergence angle θ is fixed to a preset angle, a discrepancy m between the subject 4 and the viewpoint occurs when the distance to the subject 4 changes. In response to this, the repositioning unit 31a eliminates the discrepancy m between the subject 4 and the viewpoint by suitably moving the display ranges 6L and 6R, and can generate an image of the subject 4 suitable for stereoscopic viewing.

[0038] For example, let's consider the case where the distance between the subject 4 and the stereoscopic imaging device 2A increases, starting from a state where the image of the subject 4 shown in Figure 3(a) is located in the center of the display ranges 6L and 6R. In this case, the change in distance to the subject 4 causes a shift m between the subject 4 and the viewpoint, and as shown in Figure 3(b), the subject 4 moves in a direction away from each other in the imaging areas 20L and 20R. In response to this, as shown in Figure 3(c), the repositioning unit 31a moves the left and right display ranges 6L and 6R to follow the image of the subject 4, thereby displaying the image of the subject 4 in the center of the display areas 3L and 3R.

[0039] Next, we will explain the case where the distance between the subject 4 and the stereoscopic imaging device 2A decreases, starting from the state in Figure 4(a) where the image of the subject 4 is located in the center of the display ranges 6L and 6R. In this case, the change in distance to the subject 4 causes a shift m between the subject 4 and the viewpoint, and as shown in Figure 4(b), the subject 4 moves in a direction that brings them closer together in the imaging areas 20L and 20R. In response to this, as shown in Figure 4(c), the repositioning unit 31a moves the left and right display ranges 6L and 6R to follow the image of the subject 4, thereby displaying the image of the subject 4 in the center of the display areas 3L and 3R.

[0040] <<Repositioning Method 1>> Here, we will explain the first control method by the repositioning unit 31a. First, the distance measuring unit 22b measures the distance to the subject 4. Next, the repositioning unit 31a calculates the misalignment m [mm] between the subject 4 and the viewpoint and the magnification ratio based on the measured distance. Next, the repositioning unit 31a calculates the offset amount [pixels] between the center of the image of the subject 4 and the center of the display areas 3L and 3R based on the misalignment m between the subject 4 and the viewpoint, the magnification ratio, and the number of pixels in the horizontal direction of the display areas 3L and 3R. Next, the repositioning unit 31a aligns the center of the image of the subject 4 with the center of the display areas 3L and 3R by moving the display areas 6L and 6R based on the calculated offset amount.

[0041] <<Rearrangement Method Part 2>> Next, the control method part 2 by the rearrangement unit 31a will be described. First, based on experiments, a database having the relationship between the imaging distance and the offset amount between the center of the image of the subject 4 and the centers of the display regions 3L and 3R, and / or a relational expression (approximate expression) between the imaging distance and the offset amount [pixel] based on the database is generated in advance. Subsequently, the distance measurement unit 22b measures the distance to the subject 4. Subsequently, the rearrangement unit 31a calculates the offset amount based on the measured distance and the database or the relational expression. Subsequently, the rearrangement unit 31a moves the display ranges 6L and 6R based on the calculated offset amount, thereby aligning the center of the image of the subject 4 and the centers of the display regions 3L and 3R.

[0042] As shown in FIG. 5, the offset amount is the amount of deviation (i.e., the above-mentioned deviation m) in the image width direction between the display center where the image of the subject 4 (4L, 4R) should be displayed and the center of the image of the subject 4 (4L, 4R) in each of the left display region 3L where the image of the subject 4L imaged in the left imaging region 20L is displayed and the right display region 3R where the image of the subject 4R imaged in the right imaging region 20R is displayed. Offset amount [mm] = center position of the image of the subject - display center Offset amount [pixel] = offset amount [mm] × number of pixels in the image width / image width [mm]

[0043] <Magnification Change Unit> As shown in FIG. 1, the magnification change unit 31b changes the magnification of the image of the subject 4. For example, the magnification change unit 31b can display the image of the subject 4 larger by reducing the display range (increasing the magnification) (FIG. 6(a) → FIG. 6(b)), or display the image of the subject 4 smaller by expanding the display range (reducing the magnification).

[0044] Such a magnification changing unit 31b may be configured to set the magnification of the subject 4 based on the pixel size of the stereoscopic display device 3. For example, when the stereoscopic display device 3 has a relatively low resolution (i.e., when the pixel size of the stereoscopic display device 3 is large), the magnification changing unit 31b can prevent the subject 4 from being displayed large by setting the magnification small. Also, when the stereoscopic display device 3 has a relatively high resolution (i.e., when the pixel size of the stereoscopic display device 3 is small), the magnification changing unit 31b can prevent the subject 4 from being displayed small by setting the magnification large.

[0045] <Stereoscopic display device> The stereoscopic display device 3 is a device (more specifically, a stereoscopic display device for dental treatment) that displays the left and right images of the subject 4 based on the output from the display control unit 31A and allows the observer to view the displayed left and right images stereoscopically. As shown in FIG. 7(a), a display device 3X that forms part of the stereoscopic display device 3 is constituted by a liquid crystal monitor or the like, and the images of the subject 4L and 4R as the left and right imaging results are displayed on one display device 3X. As the stereoscopic display device 3 provided with such a display device 3X, the stereoscopic display devices 3E and 3F described later can be used.

[0046] On the other hand, as shown in FIG. 7(b), as an example of the stereoscopic display device 3, a stereoscopic display device 3Y displays the images of the subject 4L and 4R as the left and right imaging results on the left and right stereoscopic display devices 3YL and 3YR, respectively. As such a stereoscopic display device 3Y, a 3D monitor, 3D glasses, a VR headset, a VR goggle, etc. can be used.

[0047] ≪Example of Repositioning Operation≫ As shown in the flowchart of Figure 8, the focus change unit 22a controls the optical system drive unit 21d to execute the autofocus function and adjusts the focus position to the subject 4 (step S11). Next, the optical system drive unit 21d outputs the focus position value to the distance measuring unit 22b (step S12). Here, the focus position value is a value related to the position of the optical components of the optical system 21c associated with the autofocus function. Next, the distance measuring unit 22b calculates the distance to the subject 4 based on the focus position value (step S13). Here, the distance measuring unit 22b can calculate the distance to the subject 4 based on the relationship between the pre-stored focus position value and the distance to the subject 4. Next, the repositioning unit 31a aligns the center of the image of the subject 4 with the display ranges 6L and 6R using the repositioning method described above (step S14).

[0048] Here, the relationship between the working distance L and the focus position value has been determined in advance through experiments, and an approximation formula for the approximation curve is generated from the approximation curve of the graph of this relationship. Based on this approximation formula, the distance measuring unit 22b can calculate the distance from the focus position value to the subject 4.

[0049] The stereoscopic imaging device 2A according to the first embodiment of the present invention comprises an imaging unit 21 having imaging regions 20L and 20R divided into left and right sections, a convergence angle setting unit 10 that sets the convergence angle θ between the left and right imaging regions 20L and 20R and the subject 4, and a display control unit 31A that controls the image captured by the imaging unit 21. The convergence angle setting unit 10 sets the convergence angle θ with respect to the subject to be greater than 0° and 5° or less. Therefore, the stereoscopic imaging device 2A can broaden the range in which stereoscopic viewing is possible at a distance to the subject 4 and can suitably image the inside of narrow holes 4a of small subjects 4, such as the inside of a tooth root canal. Furthermore, the stereoscopic imaging device 2A can generate images that can reduce eye strain for the observer.

[0050] The convergence angle setting unit 10 sets the convergence angle θ to be greater than 0° and 5° or less for the subject 4 located at a working distance L of 300 mm to 1000 mm from the convergence angle setting unit 10. Therefore, the stereoscopic imaging device 2A can more effectively image the inside of narrow holes 4a of small subjects 4, such as the root canals of teeth.

[0051] The convergence angle setting unit 10 is an optical system 11 (11L, 11R) using at least one of the mirror 12 and prisms 13, 14. Therefore, the stereoscopic imaging device 2A can implement the convergence angle setting unit 10 with simple optical components.

[0052] The stereoscopic imaging device 2A includes a distance measuring unit 22b for measuring the distance to the subject 4, and the display control unit 31A arranges the left and right images based on the distance and the convergence angle θ. Therefore, the stereoscopic imaging device 2A can suitably generate stereoscopic images in response to a shift m between the subject 4 and the viewpoint caused by a change in the distance to the subject 4.

[0053] The display control unit 31A outputs the left and right images to a single display device 3X. Therefore, the stereoscopic imaging device 2A can suitably display stereoscopic images on a general-purpose display device.

[0054] The display control unit 31A outputs the positioned left and right images to the left and right display devices (stereoscopic display devices 3YL and 3YR) corresponding to the left and right images, respectively. Therefore, the stereoscopic imaging device 2A can suitably display stereoscopic images on display devices dedicated to stereoscopic viewing.

[0055] The distance measuring unit 22b measures the distance using an autofocus function. Therefore, the stereoscopic imaging device 2A can suitably measure the distance to the subject 4 using the functions of a general-purpose imaging device.

[0056] The display control unit 31A can change the display magnification of the left and right images. Therefore, the stereoscopic imaging device 2A can suitably display an image of the part of the subject 4 that should be focused on by enlarging it, or suitably display an image of the entire subject 4 by reducing it.

[0057] The convergence angle setting unit 10 includes, on both the left and right sides, a first reflective surface (reflective surface 12a) that reflects light 5 from the subject 4 outwards to the left and right, a second reflective surface (reflective surface 13b) that reflects the light 5 reflected by the first reflective surface toward the imaging unit 21 in the optical axis direction, a third reflective surface (reflective surface 13c) that reflects the light reflected by the second reflective surface toward the left and right, and a fourth reflective surface (reflective surfaces 14a, 14b) that reflects the light reflected by the third reflective surface toward the optical axis direction and causes it to enter the imaging unit 21. Therefore, the stereoscopic imaging device 2A can achieve the distance to the subject 4 and the convergence angle θ with fewer reflective surfaces.

[0058] Furthermore, the stereoscopic observation system 1A according to the first embodiment of the present invention comprises a stereoscopic imaging device 2A and a stereoscopic display device 3 that displays the image captured by the stereoscopic imaging device 2A. Therefore, the stereoscopic observation system 1A can suitably capture the subject 4 as a stereoscopic image and suitably display it as a stereoscopic image. In addition, the stereoscopic observation system 1A can reduce eye strain for the observer.

[0059] <Second Embodiment> Next, the stereoscopic observation system according to the second embodiment of the present invention will be described, focusing on the differences from the stereoscopic observation system 1A according to the first embodiment. As shown in Figure 9, the stereoscopic observation system 1B according to the second embodiment of the present invention is equipped with a stereoscopic imaging device 2B instead of the stereoscopic imaging device 2A.

[0060] The stereoscopic imaging device 2B includes an imaging device 20B in place of the imaging device 20A, and also includes a distance measuring unit 40. The imaging device 20B includes an imaging control unit 22B in place of the imaging control unit 22A. The imaging control unit 22B does not include a distance measuring unit 22b.

[0061] <Distance Measurement Unit> The distance measurement unit 40 is configured separately from the imaging control unit 22B and is a distance sensor (infrared sensor, etc.) that detects the distance to the subject 4 and outputs the detection result to the control unit 30A. The distance measurement unit 40 measures the length of the optical path of the light 5 reflected by the convergence angle setting unit 10 as the distance from the distance sensor, which is the image sensor 21b or the distance measurement unit 22b, to the subject 4.

[0062] <<Example of repositioning operation>> In this example of operation, the distance measuring unit 40 is a distance sensor that measures the distance to the subject 4. As shown in the flowchart of Figure 10, the distance measuring unit 40 measures the distance to the subject 4 (step S21). Next, the focus changing unit 22a adjusts the focal position to the measured distance by controlling the optical system drive unit 21d (step S22). Subsequently, the repositioning unit 31a aligns the center of the image of the subject 4 with the display ranges 6L and 6R using the repositioning method described above (step S23).

[0063] In the stereoscopic imaging device 2B according to the second embodiment of the present invention, the distance measuring unit 40 is a distance sensor that measures the distance to the subject 4. Therefore, the stereoscopic imaging device 2B can suitably measure the distance to the subject 4 using, for example, an infrared sensor.

[0064] <Third Embodiment> Next, the stereoscopic observation system according to the third embodiment of the present invention will be described, focusing on the differences from the stereoscopic observation system 1A according to the first embodiment. As shown in Figure 11, the stereoscopic observation system 1C according to the third embodiment of the present invention includes a stereoscopic imaging device 2C instead of the stereoscopic imaging device 2A. The stereoscopic imaging device 2C includes a convergence angle setting unit 10 similar to that of the first embodiment. However, in this embodiment, the convergence angle setting unit 10 is configured to vary the convergence angle θ, for example, from greater than 0° to 5° or less. Furthermore, the stereoscopic imaging device 2C includes a convergence angle changing unit 50 and a control unit 30C instead of the control unit 30A.

[0065] <Convergence Angle Changing Section> The convergence angle changing section 50 is composed of a motor, a transmission mechanism that transmits the motor's power to the mirror 12, etc., and changes the convergence angle θ by changing the orientation of the mirror 12 (12L, 12R) (see Figure 12).

[0066] <Control Unit> The control unit 30C includes a display control unit 31C as a functional unit, replacing the display control unit 31A. The display control unit 31C does not include a repositioning unit 31a. Furthermore, the control unit 30C includes a congestion angle control unit 32 as a functional unit. In other words, the control unit 30C has a configuration in which the repositioning unit 31a is omitted by including the congestion angle control unit 32.

[0067] <Convergence Angle Control Unit> The convergence angle control unit 32 controls the convergence angle changing unit 50 based on the distance to the subject 4 measured by the distance measuring unit 22b. That is, the convergence angle control unit 32 changes the convergence angle θ by changing the orientation of the mirror 12 based on the distance to the subject 4, and by aligning the center of the image of the subject 4 with the centers of the display areas 3L and 3R, it is possible to generate an image of the subject 4 that is suitable for stereoscopic viewing.

[0068] <<Example of repositioning operation>> As shown in the flowchart of Figure 13, the focus change unit 22a controls the optical system drive unit 21d to execute the autofocus function and adjust the focus position to the subject 4 (step S11). Next, the optical system drive unit 21d outputs the focus position value to the distance measuring unit 22b (step S12). Next, the distance measuring unit 22b calculates the distance to the subject 4 based on the focus position value (step S13). Next, the convergence angle control unit 32 sets the convergence angle θ by controlling the convergence angle change unit 50 based on the calculated distance and aligns the center of the image of the subject 4 with the display areas 3L and 3R (step S15).

[0069] The stereoscopic imaging device 2C according to the third embodiment of the present invention includes a distance measuring unit 22b for measuring the distance to the subject 4, a convergence angle changing unit 50 for changing the convergence angle θ set by the convergence angle setting unit 10, and a convergence angle control unit 32 for controlling the convergence angle changing unit 40, wherein the convergence angle control unit 32 controls the convergence angle changing unit 50 to set the convergence angle θ based on the distance. Therefore, the stereoscopic imaging device 2B can suitably generate stereoscopic images in response to changes in the distance to the subject 4.

[0070] <Fourth Embodiment> Next, the stereoscopic observation system according to the fourth embodiment of the present invention will be described, focusing on the differences from the stereoscopic observation system 1C according to the third embodiment. As shown in Figure 14, the stereoscopic observation system 1D according to the fourth embodiment of the present invention is equipped with a stereoscopic imaging device 2D instead of the stereoscopic imaging device 2C.

[0071] The stereoscopic imaging device 2D includes an imaging device 20B instead of imaging device 20A, and also includes a distance measuring unit 40. The imaging device 20B includes an imaging control unit 22B instead of imaging control unit 22A. The imaging control unit 22B does not include a distance measuring unit 22b.

[0072] <Distance Measurement Unit> The distance measurement unit 40 is configured separately from the image control unit 22B and is a distance sensor (infrared sensor, etc.) that detects the distance to the subject 4 and outputs the detection result to the control unit 30A. The distance measurement unit 40 measures the length of the optical path of the light 5 reflected by the convergence angle setting unit 10 as the distance from the image sensor 21b or the distance measurement unit 40 to the subject 4.

[0073] <<Example of repositioning operation>> In this operation example, the distance measuring unit 40 is a distance sensor that measures the distance to the subject 4. As shown in the flowchart of Figure 15, the distance measuring unit 40 measures the distance to the subject 4 (step S21). Next, the focus changing unit 22a adjusts the focal position to the measured distance by controlling the optical system drive unit 21d (step S22). Subsequently, the convergence angle control unit 32 sets the convergence angle θ by controlling the convergence angle changing unit 50 based on the measured distance, and aligns the center of the image of the subject 4 with the display areas 3L and 3R (step S24).

[0074] In the stereoscopic imaging device 2D according to the fourth embodiment of the present invention, the distance measuring unit 40 is a distance sensor that measures the distance to the subject 4. Therefore, the stereoscopic imaging device 2D can suitably measure the distance to the subject 4 using, for example, an infrared sensor.

[0075] <Fifth Embodiment> Next, the stereoscopic observation system according to the fifth embodiment of the present invention will be described, focusing on the differences from the stereoscopic observation systems 1A, 1B, 1C, and 1D according to the first to fourth embodiments. As shown in Figure 16, the stereoscopic observation system 1E according to the fifth embodiment includes left and right first line-of-view guidance units 51 (51L, 51R). In this embodiment, the display device 3X and the left and right first line-of-view guidance units 51 constitute a stereoscopic display device 3E that allows the observer to view the subject 4 captured by the stereoscopic imaging devices 2A to 2D in stereoscopic form.

[0076] <First line of sight guidance unit> The first line of sight guidance unit 51 is interposed between the observer's eye and the display device 3X, and is a convex lens that guides light from the observer's eye side to the respective display centers (centers in the left-right direction) of the left and right images on the display device 3X. The left first line of sight guidance unit 51L is the left eye E of the observer. L (See Figure 17) It is interposed between the left display area 3L of the display device 3X and the observer's left eye E L The right first eye-tracking unit 51R guides the observer's gaze to the center of the image of the subject 4 in the left display area 3L of the display device 3X. R (See Figure 17) It is interposed between the right display area 3R of the display device 3X and the observer's right eye ER The gaze is guided to the center of the image of the subject 4 in the right display area 3R of the display device 3X. The first gaze guidance unit 51, through the light-gathering properties of the convex lens, can guide the left and right lines of sight of any observer with any interpupillary distance to the display centers of the left and right images.

[0077] Furthermore, as shown in Figure 17, the convergence angle θ1 of the virtual image 4X of the subject 4 displayed on the display device 3X, which is observed by the observer via the first line-of-sight guidance unit 51, is equal to the convergence angle θ set by the convergence angle setting unit 10. In addition, the display control unit 31A (see Figure 1) or the display control unit 31C (see Figure 14) can display the left and right images on the display device 3X such that the convergence angle θ1 of the virtual image 4X of the displayed subject 4 is equal to the convergence angle θ, based on the convergence angle θ set by the convergence angle setting unit 10.

[0078] For example, when the convergence angle θ set by the convergence angle setting unit 10 is 2.86°, the distance between the centers of the left and right first line-of-sight guide units 51 is set to 65 mm, which is the average interpupillary distance. In this case, the distance b between the first line-of-sight guide unit 51 and the virtual image 4X (virtual image distance) is 1302 mm. If the first line-of-sight guide unit 51 is a convex lens with a focal length f = 90 mm, in order to achieve this virtual image distance b, the distance a between the first line-of-sight guide unit 51 and the display device 3X (monitor distance) is set to 84.2 mm. 1 / f = 1 / a - 1 / b a = bf / (b + f) ≈ 84.2 When the monitor distance a is set to 84.2 mm, the viewpoint on the display device 3X is located 30.4 mm to the left or right of the center of the display device 3X. The display control units 31A and 31C align the center of the image of the subject 4 with the viewpoint positions of the left display area 3L and the right display area 3R of the display device 3X and display it. Since the widthwise distance between the center of the display device 3X and the viewpoint is approximately equal to half the interpupillary distance, the observer can observe the virtual image 4X while looking straight ahead at a distant object. Therefore, the stereoscopic observation system 1E can reduce observer fatigue during prolonged observation.

[0079] Furthermore, when a 5.5-inch monitor is used as the display device 3X, the centers of the left and right images on the display device 3X are located 30.36 mm from the center of the display device 3X. The difference between this distance and half of the average interpupillary distance of 65 mm is 2.14 mm. When the convergence angle θ set by the convergence angle setting unit 10 is 2.86°, and the centers of the left display area 3L and the right display area 3R of the display device 3X are aligned with the left and right viewpoints of the observer on the display device 3X, the distance a between the left and right first line-of-view guide units 51 and the display device 3X becomes 85.7 mm. When the first line-of-view guide unit 51 is a convex lens with a focal length f = 90 mm, the distance b between the first line-of-view guide unit 51 and the virtual image 4X of the subject 4 displayed on the display device 3X (virtual image distance) becomes 1794 mm. Therefore, the stereoscopic observation system 1E uses the display control units 31A and 31C to align the centers of the left and right subject images 4 with the centers of the left display area 3L and the right display area 3R of the display device 3X, thereby allowing the observer to view the images of the subject 4 in stereoscopic form.

[0080] In the stereoscopic observation system 1E according to the fifth embodiment of the present invention, the stereoscopic display device 3E includes a display device 3X that displays the left and right images corresponding to the left and right imaging areas, output by the display control units 31A and 31C, in left and right display areas, respectively, and left and right first line-of-view guidance units 51L and 51R that are provided corresponding to the centers of the left and right display areas in the display device 3X and are capable of focusing light toward the centers of the left and right display areas. Therefore, the stereoscopic observation system 1E can suitably allow the observer to view the image of the subject 4 in stereoscopic form even when the distance between the observer's left and right eyes is different.

[0081] The convergence angle θ1 of the image displayed by the stereoscopic display device 3E is equal to the convergence angle θ set by the convergence angle setting unit 10. Therefore, the stereoscopic observation system 1E can allow the observer to view the image of the subject 4 in stereoscopic form.

[0082] <Sixth Embodiment> Next, the stereoscopic observation system according to the sixth embodiment of the present invention will be described, focusing on the differences from the stereoscopic observation system 1E according to the fifth embodiment. As shown in Figure 18, the stereoscopic observation system 1F according to the sixth embodiment of the present invention includes left and right second line-of-view guidance units 52 (52L, 52R). In this embodiment, the display device 3X, the left and right first line-of-view guidance units 51, and the left and right second line-of-view guidance units 52 constitute a stereoscopic display device 3F that allows the observer to view the subject 4 captured by the stereoscopic imaging devices 2A to 2D in stereoscopic form.

[0083] <Second Eye-Tracking Unit> The second eye-tracking unit 52 is interposed between the first eye-tracking unit 51 and the display device 3X, and is a wedge prism (wedge lens) that guides the light focused by the first support guidance unit 51 to the respective display centers (left-right center) of the left and right images on the display device 3X. The left second eye-tracking unit 52L is interposed between the left first eye-tracking unit 51L and the left display area 3L of the display device 3X, and guides the observer's left eye E L The right second gaze guidance unit 52R is interposed between the right first gaze guidance unit 51R and the right display area 3R of the display device 3X, and guides the observer's right eye E R The user's gaze is guided to the center of the right image displayed in the right display area 3R of the display device 3X.

[0084] For example, if a 7-inch monitor is used as the display device 3X, the centers of the left and right images on the stereoscopic display device 3X will be located 38.675 mm from the center of the display device 3X. This distance is significantly different from half of the average pupillary distance of 65 mm. In contrast, the stereoscopic observation system 1F can guide the observer's gaze to the center of the images displayed in the left display area 3L and the right display area 3R, respectively, using the second gaze guidance unit 52. Therefore, the stereoscopic observation system 1F can enable the observer to view the images of the subject 4 stereoscopically by using the display control units 31A and 31C to align the centers of the left and right subject 4 images with the centers of the left display area 3L and the right display area 3R, respectively, of the display device 3X.

[0085] In the stereoscopic observation system 1F according to the sixth embodiment of the present invention, the stereoscopic display device 3F is provided between the left and right first eye-tracking units 51L, 51R and the left and right display areas of the display device 3X, and includes second eye-tracking units 52L, 52R capable of guiding the light focused by the left and right first eye-tracking units 51L, 51R toward the center of the left and right display areas, respectively. Therefore, the stereoscopic observation system 1F can suitably allow the observer to view the image of the subject 4 in stereoscopic form by using the second eye-tracking units 52L, 52R according to the size (left-right dimension) of the stereoscopic display device 3X.

[0086] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified as appropriate without departing from the spirit of the invention. For example, the first line of sight guidance unit 51 and the second line of sight guidance unit 52 of the stereoscopic observation systems 1E and 1F according to the fifth and sixth embodiments can also be applied to the stereoscopic observation systems 1C and 1D according to the third and fourth embodiments.

[0087] 1A, 1B, 1C, 1D, 1E, 1F Stereoscopic observation system (Stereoscopic observation system for dental treatment) 2A, 2B, 2C, 2D Stereoscopic imaging device (Stereoscopic imaging device for dental treatment) 3, 3Y, 3E, 3F Stereoscopic display device (Stereoscopic display device for dental treatment) 3X Display device 10 Convergence angle setting unit 20 Imaging device 20L, 20R Imaging area 22b Distance measurement unit 31A, 31B Display control unit 32 Convergence angle control unit 40 Distance measurement unit 50 Convergence angle changing unit 51, 51L, 51R First line of sight guidance unit 52, 52L, 52R Second line of sight guidance unit

Claims

1. A stereoscopic imaging device for dental treatment comprising: an imaging unit having imaging areas divided into left and right sections; a convergence angle setting unit for setting the convergence angle between the left and right imaging areas and a subject; and a display control unit for controlling the image captured by the imaging unit, wherein the convergence angle setting unit sets the convergence angle to greater than 0° and 5° or less for a subject located at a distance of 300 mm to 1000 mm from the convergence angle setting unit.

2. The stereoscopic imaging device for dental treatment according to claim 1, characterized in that the subject is the root canal of a tooth.

3. The stereoscopic imaging apparatus for dental treatment according to claim 1, characterized in that the convergence angle setting unit is an optical system using at least one of a mirror and a prism.

4. The stereoscopic imaging device for dental treatment according to claim 1, comprising a distance measuring unit for measuring the distance to the subject, wherein the display control unit arranges the left and right images based on the distance and the convergence angle.

5. The stereoscopic imaging apparatus for dental treatment according to claim 3, characterized in that the display control unit outputs the arranged left and right images to a single display device.

6. The stereoscopic imaging apparatus for dental treatment according to claim 3, characterized in that the display control unit outputs the arranged left and right images to left and right display devices corresponding to the left and right images, respectively.

7. A stereoscopic imaging device for dental treatment according to claim 1, comprising: a distance measuring unit for measuring the distance to the subject; a convergence angle changing unit for changing the convergence angle set by the convergence angle setting unit; and a convergence angle control unit for controlling the convergence angle changing unit, wherein the convergence angle control unit controls the convergence angle changing unit to set the convergence angle based on the distance.

8. The stereoscopic imaging device for dental treatment according to claim 4 or 7, characterized in that the distance measuring unit measures the distance using an autofocus function.

9. The stereoscopic imaging apparatus for dental treatment according to claim 4 or 7, characterized in that the distance measuring unit is a distance sensor for measuring the distance to the subject.

10. The stereoscopic imaging apparatus for dental treatment according to claim 1, characterized in that the display control unit can change the display magnification of the left and right images.

11. The convergence angle setting unit is characterized in that it comprises, on the left and right sides, a first reflective surface that reflects light from the subject outward to the left and right; a second reflective surface that reflects the light reflected by the first reflective surface in the direction of the imaging unit in the optical axis direction; a third reflective surface that reflects the light reflected by the second reflective surface inward to the left and right; and a fourth reflective surface that reflects the light reflected by the third reflective surface in the optical axis direction and causes it to enter the imaging unit.

12. A stereoscopic observation system for dental treatment, comprising: a stereoscopic imaging device for dental treatment according to claim 1 or claim 2; and a stereoscopic display device for dental treatment that displays an image captured by the stereoscopic imaging device for dental treatment.

13. The stereoscopic dental observation system according to 12, comprising: a display device that displays left and right images corresponding to the left and right imaging areas output by the display control unit in left and right display areas, respectively; and left and right first line-of-view guide units provided corresponding to the centers of the left and right display areas in the display device and capable of focusing light toward the centers of the left and right display areas.

14. The stereoscopic observation system for dental treatment according to claim 13, wherein the stereoscopic display device for dental treatment is provided between the left and right first eye-tracking units and the left and right display areas of the display device, and is equipped with second eye-tracking units capable of guiding the light focused by the left and right first eye-tracking units toward the centers of the left and right display areas, respectively.

15. The stereoscopic observation system for dental treatment according to claim 12, characterized in that the convergence angle of the image displayed by the stereoscopic display device for dental treatment is equal to the convergence angle set by the convergence angle setting unit.

Images