Medical treatment microscope

Abstract

To provide a medical treatment microscope which enables an observer to stereoscopically view an image of an observation object with a natural feeling.SOLUTION: The medical examination microscope 10 includes an objective optical system 122, an image sensor 122, a display device 132, and an eyepiece optical system 131 that guides image light from the display device 132 to an observer, wherein the objective optical system 122 includes an objective optical system 122a and an objective optical system 122b, the objective optical system 122a and the objective optical system 122b are arranged so that a convergence angle is formed by an optical axis of the objective optical system 122a and an optical axis of the objective optical system 122b, the number of horizontal pixels or the number of vertical pixels of the display device 132 is 2000 or more and 4000 or less, and a view angle of the eyepiece optical system 131 is 35 degrees or more and 60 degrees or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a diagnostic microscope used in medical examinations. [Background technology]

[0002] Medical practitioners often use diagnostic microscopes to observe areas of interest on patients. In recent years, 3D digital microscopes have been gaining attention as a diagnostic microscope for observing areas of interest on patients, replacing optical stereo microscopes.

[0003] For example, Patent Publication No. 6469292 (Patent Document 1) describes a system configured to display images of teeth captured by an imaging element installed in a microscope on a display unit, allowing an observer to perform dental treatment while viewing the tooth images in stereoscopic view. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6469292 Summary of the Invention [Problem to be solved by the invention]

[0005] When an optical stereo microscope is used, the observer can directly view the treatment area as it is through the lenses. However, when a 3D digital microscope is used, the observer does not view the treatment area directly through the lenses, but rather views the image obtained by capturing the treatment area. For this reason, 3D digital microscopes require some ingenuity to enable the image to be viewed in three dimensions in a natural way, as if the treatment area were being viewed directly through the lenses. However, no medical microscopes with such ingenuity are currently available.

[0006] An object of the present disclosure is to provide a diagnostic microscope that allows an observer to see an image of an object to be observed in a natural stereoscopic manner. [Means for solving the problem]

[0007] The diagnostic microscope according to the present disclosure includes an objective optical system, an imaging element for capturing an image of a subject formed via the objective optical system, a display element for displaying the image acquired by the imaging element, and an eyepiece optical system for guiding image light from the display element to an observer; the objective optical system includes a first objective optical system and a second objective optical system; the imaging element includes a first imaging element corresponding to the first objective optical system and a second imaging element corresponding to the second objective optical system; the display element includes a first display element corresponding to the first imaging element and a second display element corresponding to the second imaging element; the eyepiece optical system includes a first eyepiece optical system corresponding to the first display element and a second eyepiece optical system corresponding to the second display element; the first objective optical system and the second objective optical system are arranged such that an angle of convergence is formed between the optical axis of the first objective optical system and the optical axis of the second objective optical system; the number of horizontal or vertical pixels of the display element is 2000 or more and 4000 or less; and the field of view of the eyepiece optical system is 35 degrees or more and 60 degrees or less. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a diagnostic microscope that allows an observer to see an image of an observation target in a natural stereoscopic manner. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a configuration example of a microscope according to an embodiment of the present invention and a system using the microscope; [Figure 2] FIG. 2 is a block diagram showing a detailed configuration of a microscope. [Figure 3] FIG. 1 is a schematic diagram for explaining the principle of stereoscopic viewing using a microscope. [Figure 4]1 is a diagram for explaining the difference between the microscope according to the present embodiment and Comparative Example 1. FIG. [Figure 5] FIG. 2 is a diagram showing the configuration of an eyepiece unit. [Figure 6] FIG. 10 is a diagram showing the relationship between the viewing angle and the number of pixels. [Figure 7] FIG. 1 is a conceptual diagram for explaining the apparent distance to a screen in stereoscopic viewing. [Figure 8] FIG. 10 is a conceptual diagram for explaining a chief ray angle. [Figure 9] FIG. 2 is a diagram for explaining a working distance from an objective unit to a subject. [Figure 10] 10A and 10B are diagrams for explaining the relationship between the convergence angle and the focus adjustment range. [Figure 11] 10 is a graph showing the relationship between the convergence angle and the focus adjustment range. [Figure 12] FIG. 10 is a diagram for explaining a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and the description thereof will not be repeated.

[0011] <Overall structure> FIG. 1 is a schematic diagram showing a microscope 10 according to the present embodiment and an example configuration of a system using the microscope 10. An example system to which the microscope 10 according to the present embodiment is applied will be described using FIG. 1. The microscope 10 is a diagnostic microscope used for diagnostic purposes. Here, dental treatment is cited as an example of diagnostic purposes. However, the microscope 10 according to the present disclosure can also be applied to diagnostics in other medical departments, such as surgery and dermatology, in addition to dental treatment.

[0012] FIG. 1 shows an example of a system including a microscope 10 and a chair unit 20. The microscope 10 and chair unit 20 are communicatively connected via a CAN (Controller Area Network). The microscope 10 is supported by an arm 302 rotatably attached to a pole 301. The microscope 10 is a digital stereo microscope. The microscope 10 has the function of capturing three-dimensional images of a subject and allowing an observer to view the image of the subject in stereoscopic form. The arm 302 may be attached to a support member extending from the ceiling or wall.

[0013] The microscope 10 includes a pair of objective units 12, a pair of eyepiece units 13, a pair of handles 102, and a housing 101. In FIG. 1, the microscope 10 is illustrated from an angle where only one of the pair of objective units 12, the pair of eyepiece units 13, and the pair of handles 102 is visible. Therefore, the other objective unit 12, the other eyepiece unit 13, and the other handle 102 are not shown in FIG. 1. The housing 101 is attached to the tip of an arm 302. The housing 101 houses the pair of objective units 12 and the pair of eyepiece units 13. The pair of handles 102 are provided on the housing 101.

[0014] The objective unit 12 includes an objective optical system such as an objective lens 1210, and the eyepiece unit includes an eyepiece optical system such as an eyepiece lens 1310. The part of the objective unit 12 that includes the objective lens 1210 protrudes from the housing 101 and is directed toward the subject. The part of the eyepiece unit 13 that includes the eyepiece lens 1310 protrudes from the housing 101 and is directed toward the observer's eye.

[0015] The microscope 10 captures a pair of subject images captured by a pair of objective units 12, and generates a pair of images for stereoscopic viewing. The pair of objective units 12 function as an imaging device (camera). An observer views the pair of images with both eyes through a pair of eyepiece units 13. At this time, a stereoscopic image of the subject is provided to the observer.

[0016] The observer is, for example, a surgeon. The subject is, for example, a patient. During dental treatment, the subject is the patient's oral cavity. The oral cavity includes teeth, periodontal tissue, tongue, and salivary glands. To observe the oral cavity, the surgeon moves the microscope 10 by holding the handle 102 and finely adjusts the observation range.

[0017] The chair unit 20 includes a treatment chair 21, a foot controller 23, and a base 29. A patient receives treatment from a surgeon on the treatment chair 21. A basin unit 27 is arranged around the treatment chair 21. The chair unit 20 may also include the basin unit 27. The basin unit 27 includes a cleaning unit 28. The cleaning unit 28 is equipped with a water tap and a saliva basin. The patient rinses the inside of the mouth using the cleaning unit 28. An instrument stand may be arranged around the treatment chair 21. The instrument stand may have a storage section for storing multiple types of instruments such as cutting tools and treatment instruments.

[0018] The examination chair 21 includes a seat 211, a backrest 212, and a headrest 213. The seat 211 is attached to a base 29. The base 29 has a mechanism for raising and lowering the seat 211. The backrest 212 is attached to the seat 211 so as to be tiltable relative to the seat 211. The headrest 213 is attached to the backrest 212 so as to be tiltable relative to the backrest 212.

[0019] The foot controller 23 has a plurality of pedals that are operated by the surgeon. The plurality of pedals includes a pedal for driving the base 29, a pedal for driving the backrest 212, and a pedal for driving the headrest 213. The surgeon changes the posture of the examination chair 21 to an appropriate position by stepping on the plurality of pedals.

[0020] 1 illustrates a position in which the backrest 212 is approximately horizontal with respect to the seat 211, and the headrest 213 is approximately horizontal with respect to the backrest 212. The position of the examination chair 21 is determined by the height of the seat 211, the tilt angle of the backrest 212, and the tilt angle of the headrest 213.

[0021] <Hardware configuration> Fig. 2 is a block diagram showing a detailed configuration of the microscope 10. As shown in Fig. 2, the microscope 10 includes a pair of observation units 11a and 11b and a control device 14. Hereinafter, the observation units 11a and 11b will be collectively referred to as "observation units 11."

[0022] The observation unit 11 includes an objective unit 12 and an eyepiece unit 13. The control device 14 controls the objective unit 12 and the eyepiece unit 13.

[0023] The control device 14 includes a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory). The CPU executes operating programs stored in the ROM or the like. The ROM stores programs executed by the CPU and other data. The RAM serves as a working area for the CPU when it executes programs, temporarily storing programs and data used for executing the programs. The control devices 14 and 24 may be configured with at least one semiconductor integrated circuit such as a processor, at least one application specific integrated circuit (ASIC), at least one digital signal processor (DSP), at least one field programmable gate array (FPGA), and / or other circuits having a processing function. The control device 14 may also be configured with processing circuitry.

[0024] Each of the pair of observation units 11 includes an objective unit 12 and an eyepiece unit 13. Hereinafter, the objective unit 12 provided in the observation unit 11a will be referred to as the "objective unit 12a," and the objective unit 12 provided in the observation unit 11b will be referred to as the "objective unit 12b." Similarly, hereafter, the eyepiece unit 13 provided in the observation unit 11a will be referred to as the "eyepiece unit 13a," and the eyepiece unit 13 provided in the observation unit 11b will be referred to as the "eyepiece unit 13b."

[0025] That is, "objective unit 12" is a general term for "objective units 12a and 12b," and "eyepiece unit 13" is a general term for "eyepiece units 13a and 13b."

[0026] The objective unit 12 includes an objective optical system 121 and an image sensor 122. The eyepiece unit 13 includes an eyepiece optical system 131 and a display element 132. Hereinafter, the objective optical system 121 provided in the objective unit 12a will be referred to as the "objective optical system 121a," the objective optical system 121 provided in the objective unit 12b will be referred to as the "objective optical system 121b," the image sensor 122 provided in the objective unit 12a will be referred to as the "image sensor 122a," and the image sensor 122 provided in the objective unit 12b will be referred to as the "image sensor 122b."

[0027] That is, "objective optical system 121" is a general term for "objective optical systems 121a and 121b," and "imaging element 122" is a general term for "imaging elements 122a and 122b."

[0028] Similarly, in the following, the eyepiece optical system 131 provided in the eyepiece unit 13a will be referred to as the "eyepiece optical system 131a," the eyepiece optical system 131 provided in the eyepiece unit 13b will be referred to as the "eyepiece optical system 131b," the display element 132 provided in the eyepiece unit 13a will be referred to as the "display element 132a," and the display element 132 provided in the eyepiece unit 13b will be referred to as the "display element 132b."

[0029] That is, "ocular optical system 131" is a general term for "ocular optical systems 131a and 131b," and "display element 132" is a general term for "display elements 132a and 132b." Display element 132 displays an image acquired by image sensor 122. Eyepiece optical system 131 guides image light from display element 132 to the viewer.

[0030] The imaging element 122 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The shape of the imaging area of ​​the imaging element 122 is, for example, a square. Note that the shape of the imaging area of ​​the imaging element 122 does not have to be a square, and may be, for example, a rectangle other than a square. The display element 132 constitutes, for example, a flat panel display such as an LCD (Liquid Crystal Display) or an organic EL (Electroluminescence) display. The imaging element 122 captures an object image formed via the objective optical system 121.

[0031] <Principles of stereoscopic vision> 3 is a schematic diagram for explaining the principle of stereoscopic vision using the microscope 10. The principle of stereoscopic vision using the microscope 10 will be explained using FIG.

[0032] As shown in FIG. 3, the pair of objective units 12a, 12b are arranged so that a convergence angle is formed at the intersection of the optical axes passing through the centers of the objective lenses 1210, 1210. A subject is located at the intersection of the optical axes. FIG. 3 shows a patient's oral cavity as an example of the subject. The pair of image capturing elements 122a, 122b capture an image of the subject captured by the objective lens 1210 and output an image signal to the control device 14. A positional shift occurs between the image captured by the image capturing element 122a and the image captured by the image capturing element 122b according to the convergence angle. This positional shift corresponds to "parallax."

[0033] The control device 14 displays the image acquired by the imaging element 122a on the display element 132a (see FIG. 2), and displays the image acquired by the imaging element 122b on the display element 132b (see FIG. 2). As a result, a pair of images that create parallax are displayed on the display elements 132a and 132b. The observer observes the pair of images through the pair of eyepiece units 13a and 13b shown in FIG. 2. This allows the observer to see the subject in stereoscopic view.

[0034] <Comparison between this embodiment and comparative example 1> 4 is a diagram illustrating the difference between a microscope 10 according to this embodiment and Comparative Example 1. The microscope according to Comparative Example 1 is an optical stereo microscope 1000. The optical stereo microscope 1000 includes a pair of objective units 1200 and a pair of eyepiece units 1300. The microscope 10 according to this embodiment includes a pair of objective units 12 and a pair of eyepiece units 13.

[0035] The microscope 10 and the optical stereo microscope 1000 have in common the fact that they are equipped with a pair of objective units and a pair of eyepiece units. It goes without saying that the objective unit 12 (1200) and the eyepiece unit 13 (1300) each include an optical system, the optical system of the objective unit 12 (1200) includes an objective lens, and the optical system of the eyepiece unit 13 (1300) includes an eyepiece lens.

[0036] The optical stereo microscope 1000 delivers an image of the object to be observed directly to the observer's eyes via an optical path OP1 in the objective unit 1200 and the eyepiece unit 1300. This allows the observer to observe the object as it is through the objective lens of the objective unit 1200 and the eyepiece lens of the eyepiece unit 1300.

[0037] In contrast, the microscope 10 captures an image of the object of observation that enters the objective unit 12 via optical path OP2 using the image sensor 122, and displays the captured image on the display device 132 in the eyepiece unit 12. The observer observes the image delivered from the display device 132 via optical path OP3. In this way, the microscope 10 is a "3D digital microscope."

[0038] In the case of a 3D digital microscope, the objective unit and the eyepiece unit can be operated independently, which allows for greater freedom in treatment posture.

[0039] Furthermore, with the optical stereo microscope 1000, when laser light used in dental treatment enters the objective lens, there is a risk that the laser light will directly enter the observer's eyes. In contrast, with a 3D digital microscope, there is no such risk. As such, the 3D digital microscope has many advantages that are not available with the optical stereo microscope 1000.

[0040] However, a challenge with 3D digital microscopes is how to allow the observer to see the object in stereoscopic view in a natural way (as it is) by devising ways to capture images and display the images. Simply put, a challenge with "3D digital microscopes" is how to allow the observer to see the image of the object in stereoscopic view in a natural way. This challenge does not arise in Comparative Example 1, which provides the observer with an image of the object itself through a lens. In this embodiment, in order to solve this challenge, more specific design values ​​and the like required for a 3D digital microscope will be described using microscope 10 as an example.

[0041] <Eyepiece unit configuration> Fig. 5 is a diagram showing the configuration of the eyepiece unit 13. As shown in Fig. 5, the eyepiece unit 13 includes a display element 132 and an eyepiece optical system 131. The eyepiece optical system 131 includes an eyepiece lens 1310 and a field lens 1311. The observer looks through the eyepiece lens 1310 to observe the image displayed on the display element 132. The eyepiece unit 13 has an optical path OP3 formed therein for guiding the image displayed on the display element 132 to the observer's pupil.

[0042] An eyepiece lens 1310 and a field lens 1311 are disposed on optical path OP3. The field lens 1311 is disposed between the display element 132 and the eyepiece lens 1310. In this manner, the eyepiece optical system 131 includes multiple lenses arranged side by side along the optical path OR3 that guides image light from the display element 132 to the observer. The combination of the field lens 1311 and the eyepiece lens 1310 corrects aberrations.

[0043] If only one eyepiece 1310 were placed in the optical path OR3, the eyepiece 1310 would function like a magnifying glass. In this case, there would be almost no distortion in the image at the center of the field of view, but at the periphery of the field of view, the image would be distorted or blurred due to the effects of aberration. Therefore, in this embodiment, multiple lenses are placed in the optical path OR3 to provide the observer with an image with minimal distortion throughout the entire field of view. Note that FIG. 5 shows two lenses as an example of multiple lenses. However, three or more lenses may be placed in the optical path OR3.

[0044] Display element 132 constitutes a screen for displaying images. Image light from the center of the screen passes through the center of field lens 1311 and the center of eyepiece lens 1310 and reaches the observer's eye, while image light from the edge of the screen is refracted by field lens 1311 and then reaches the observer's eye via eyepiece lens 1310. The observer perceives the screen on which the image is projected as extending within the range of viewing angle θv.

[0045] The field lens 1311 also contributes to reducing the size of the eyepiece 1310. If the field lens 1311 is not disposed between the display element 132 and the eyepiece 1310, the size of the eyepiece 1310 needs to be increased so that image light can be incident from one edge of the screen to the other. However, by disposing the field lens 1311 between the display element 132 and the eyepiece 1310, the optical axis can be bent in a direction toward the center of the eyepiece 1310. As a result, the diameter of the eyepiece 1310 can be reduced.

[0046] <Design values ​​for eyepiece unit 13> The design values ​​for the eyepiece unit 13 will be described. As shown in FIG. 5, the eyepoint AP of the eyepiece unit 13 is 10 mm (millimeters) or greater, the field of view θv of the eyepiece optical system in the eyepiece unit 13 is 35 degrees or greater and 60 degrees or less, the diameter of the eyepiece lens 1310 is 60 mm or less, and the number of pixels of the display element 132 is 2,000 or greater and 4,000 or less. The design value for the number of pixels may be a design value for the horizontal pixel count or a design value for the vertical pixel count. For example, if the field of view is designed to be a perfect circle, the number of horizontal pixels is the same as the number of vertical pixels. To design the field of view to be a perfect circle, the designer needs to use an image sensor 122 having a square imaging area. If an image sensor 122 having a rectangular imaging area other than a square is used, the field of view is a circle with the vertical width as its diameter.

[0047] The eyepoint AP is the distance from the lens surface of the eyepiece 1310 on the observer's side to the observer's pupil. Generally, if the eyepoint AP is short (for example, 5 mm), the eyepoint AP does not affect the observation of a naked-eye observer. However, if the eyepoint AP is short, an observer who wears glasses will need to remove their glasses to look through the eyepiece 1310.

[0048] The design value of 10 mm roughly corresponds to the distance from the eyeglasses to the observer's pupil. Therefore, by designing the eyepoint AP to be 10 mm or more, the observer can easily look through the eyepiece 1310 while wearing eyeglasses. A more preferable design value for the eyepoint AP is 17 mm or more and 20 mm or less.

[0049] FIG. 6 is a diagram showing the relationship between the viewing angle and the number of pixels. The relationship between the viewing angle θv and the number of pixels of the display element 132 will be described in detail with reference to FIG. 6. The viewing angle refers to the angle of the field of view seen when the observer looks through the eyepiece 1310. If the viewing angle is too wide, there are fewer pixels per degree of viewing angle, and the pixels become more noticeable. For this reason, if the viewing angle is too wide, the observer perceives the image as having low resolution. On the other hand, if the viewing angle is too narrow, the observer will only be able to see a small portion of the object being observed, which reduces the observer's work efficiency.

[0050] Here, we will explain the relationship between viewing angle and pixels more specifically using the unit "ppd (pixels per degree)." "ppd" refers to the number of pixels on a screen in the horizontal or vertical direction within one degree of viewing angle. For example, 60 ppd corresponds to the limit of resolution at which an observer with 1.0 visual acuity can distinguish one pixel. Therefore, when an observer with 0.7 visual acuity looks at a 60 ppd screen, the observer cannot clearly distinguish the boundary between two adjacent pixels and perceives the boundary between the two adjacent pixels as blurred. As a result, an observer with 0.7 visual acuity sees a continuous image with no boundaries between pixels.

[0051] The inventors conducted experiments and found that when a design value of 40 ppd or higher is adopted, observers with visual acuity of approximately 1.0 to 1.2 can recognize the boundaries between pixels, but the boundaries are hardly noticeable, and they perceive a natural and clear image as being displayed on the screen.

[0052] The number of horizontal or vertical pixels of the display element 132 is between 2000 and 4000, and the viewing angle θv of the eyepiece optical system 131 is between 35 and 60 degrees. Examples of combinations of pixel count and viewing angle within these ranges of pixel count and viewing angle are shown below, along with the "ppd" value.

[0053] (A) (2000 pixels, viewing angle 60 degrees), 33ppd (B) (2000 pixels, viewing angle 35 degrees), 57ppd (C) (4000 pixels, viewing angle 60 degrees), 60ppd (D) (4000 pixels, viewing angle 35 degrees), 114ppd Of the above (A) to (D), (B) to (D) satisfy the condition of "40 ppd or more." Therefore, it is desirable for designers to adopt any of (B) to (D) as the design values ​​(number of pixels, viewing angle) of the microscope 10. However, designers may also adopt (A) as the design value of the microscope 10, even though it does not satisfy the condition of "40 ppd or more."

[0054] As shown in FIG. 6, the eyepiece optical system 131 forms an image circle Cr whose maximum diameter is smaller than the horizontal width of the display element 132. The image circle Cr shown in FIG. 6 may be a perfect circle. In this case, the eyepiece optical system 131 forms an image circle Cr whose maximum diameter is smaller than the horizontal and vertical widths of the display element 132. The image circle Cr may also be an ellipse. In this case, the maximum diameter of the image circle Cr may be smaller than the horizontal width of the display element 132 and may be smaller than the vertical width of the display element 132.

[0055] Figure 7 is a conceptual diagram illustrating the apparent distance to the screen SL in stereoscopic vision. When viewing an object in stereo, the viewer gazes at a point on the object with each eye turned inward. Because the human brain unconsciously controls the distance to the object and the direction of the left and right eyes, the viewer can usually view the object in stereo without feeling any discomfort. However, when an unnatural situation occurs in which the relationship between the distance to the object and the convergence angle of the eyes is significantly different from normal, a "vergence angle conflict" occurs. When convergence angle conflict occurs, the viewer can view an object in stereo, but experiences significant eye fatigue.

[0056] Furthermore, the act of viewing an image at a close distance, such as about 30 mm from the viewer's eyes, can itself cause fatigue. Therefore, in this embodiment, the eyepiece lenses 1310 are used to adjust the "apparent distance" to the screen SL to about 250 mm, and an appropriate convergence angle is set for the pair of eyepiece optical systems 131 so that the line of sight of the viewer's left eye and right eye coincide at a distance of 250 mm. This allows for the construction of eyepiece optical systems that can provide natural, fatigue-free stereoscopic viewing. Specific examples of the convergence angle will be described later with reference to FIG. 9.

[0057] Fig. 8 is a conceptual diagram for explaining the chief ray angle θr. In the eyepiece optical system 131, a plurality of light beams are generated that travel from the screen of the display element 132 toward the viewer's pupil. Fig. 8 shows light beams Lf1 to Lf3 as an example of the plurality of light beams. The light ray generated at the center of the light beams is called the "chief ray." Fig. 8 shows chief rays Cf1 to Cf3.

[0058] The chief ray angle θr is the angle between the normal to the screen of the display element 132 and the chief ray. The chief ray angle θr of the microscope 10 according to this embodiment is a value within 1 degree. The reason for designing the chief ray angle θr to a value within 1 degree will be explained below.

[0059] The microscope 10 adjusts the diopter by changing the distance from the display element 132 to the eyepiece lens 1310 in accordance with the observer's visual acuity. For example, the control device 14 (see FIG. 2) moves the display element 132 horizontally in the direction of the optical path OR in response to an operation by the observer. When the chief ray angle θr is large, the range of the image visible to the observer changes before and after diopter adjustment. In other words, when the chief ray angle θr is large, the magnification of the eyepiece optical system 131 changes before and after diopter adjustment.

[0060] In particular, when the observer's visual acuity differs significantly between the left and right eyes, the difference in magnification between the left and right eyepiece optical systems 131 becomes large. This makes it difficult for the observer to achieve stereoscopic vision. In an experiment conducted by the inventors, it was necessary to design the movement range of the display element 132 to approximately 28 mm in order to adjust the diopter within the range that meets the JIS standard. When the chief ray angle is 1 degree, the area visible to the observer on the screen changes by approximately 0.5 mm before and after diopter adjustment. One pixel on the display element used in the experiment is 0.024 mm. Therefore, when the chief ray angle is 1 degree, the area visible to the observer on the screen changes by a screen area equivalent to approximately 21 pixels before and after diopter adjustment.

[0061] The inventors have confirmed through experiments that viewers generally do not feel uncomfortable if the change in the number of pixels due to diopter adjustment is about 20. Based on this, the inventors have concluded that it is appropriate to set the chief ray angle θr to 1 degree or less.

[0062] <Design values ​​for objective unit 12> Fig. 9 is a diagram for explaining the working distance WD from the objective unit 12 to the subject. Fig. 9 shows a patient's oral cavity as an example of the subject. As shown in Fig. 9, the objective optical system 121a and the objective optical system 121b are arranged so that the optical axis of the objective optical system 121a and the optical axis of the objective optical system 121b form a convergence angle θc.

[0063] The working distance WD of the objective optical system 121 is 250 mm or more and 450 mm or less, the convergence angle θc of the objective optical system 121 is 4 degrees or more and 8 degrees or less, and the distance Ds between the pair of objective optical systems 121, 121 is 25 mm. The working distance WD is the distance from the objective optical system 121 to the subject. More strictly speaking, the working distance WD is the distance from the lens surface of the objective lens 1210 on the subject side to the subject.

[0064] In a typical microscope, the working distance is on the order of a few millimeters. Even in the case of a typical optical stereo microscope, the working distance is on the order of 50 mm. As such, the working distance of a typical microscope is short. However, in the case of a diagnostic microscope, the observer needs to insert a diagnostic instrument (such as an air turbine) into the area to be examined while magnifying the area with the microscope. Considering the observer's operability, it is preferable for a diagnostic microscope to have a long working distance WD. Therefore, in this embodiment, the working distance WD is designed to be between 250 mm and 450 mm.

[0065] When the working distance WD is set to 250 mm or more, the diameter of the objective lens 1210 is approximately 25 mm. From the viewpoint of compactness, it is desirable to make the diameter of the objective lens 1210 small, but if the diameter is made small, the F-number (aperture value) will also become small. As a result, the illuminance of the optical system will become very low. For this reason, in this embodiment, the diameter of the objective lens 1210 is set to approximately 25 mm.

[0066] When the diameter of the objective lens 1210 is about 25 mm, the distance Ds between the objective optical system 121 (121a) and the objective optical system 121 (121b) needs to be at least 25 mm or more, taking into consideration the imaging function. Note that the distance between the objective lenses 1210 provided in each of the pair of objective optical systems 121 may be defined as "distance Ds."

[0067] When the working distance WD is 250 mm and the diameter of the objective lens 1210 is 25 mm, the convergence angle θc is approximately 5.7 degrees. The convergence angle θc increases as the distance Ds is increased. For example, when the working distance WD is 250 mm and the distance Ds is 35 mm, the convergence angle θc is approximately 8 degrees. From the perspective of the diameter of the objective lens 1210, it is desirable that the convergence angle θc be approximately 5.7 degrees or greater. Note that the working distance WD may be 250 mm or greater, and may exceed 450 mm, for example.

[0068] FIG. 10 is a diagram for explaining the relationship between the convergence angle θc and the focus adjustment range. FIG. 11 is a graph showing the relationship between the convergence angle θc and the focus adjustment range. As shown in FIG. 10, the imaging ranges 1220a and 1220b captured by the objective optical systems 121a and 121b are shifted depending on the focus distance. When the "Center" line shown in FIG. 10 is included in both the imaging range 1220a and the imaging range 1220b, the microscope 10 can acquire a pair of images for stereoscopic viewing.

[0069] 11 is a graph obtained when the working distance WS is set to 350 mm and the magnification of the objective lens 1210 is set to 33x. As shown in the graph, it can be seen that the smaller the convergence angle θc, the wider the focus range that can be ensured. In consideration of practicality, it is desirable to set the convergence angle θc to between 4 degrees and 8 degrees.

[0070] <Modification> 12 is a diagram illustrating a modified example. Eyepiece unit 130 according to the modified example differs from eyepiece unit 13 described so far in that it is provided with mirror 1315 and with two eyepieces (eyepieces 1310a and 1310b).

[0071] In eyepiece unit 130, field lens 1311 and eyepieces 1310a and 1310b are arranged so that the optical axis of field lens 1311 intersects with the optical axis of eyepieces 1310a and 1310b. Mirror 1315 refracts image light toward the observer. More specifically, mirror 1315 reflects the image light output from field lens 1311 and changes the traveling direction of the image light so that the image light is directed toward eyepieces 1310a and 1310b. Therefore, optical path OR4 of eyepiece unit 130 is bent from a direction parallel to the optical axis of field lens 1311 to a direction parallel to the optical axis of eyepieces 1310a and 1310b.

[0072] According to this modification, the size of the eyepiece unit 130 can be reduced in a direction parallel to the optical axis of the eyepieces 1310a and 1310b. This allows the observer to observe the treatment area while looking through the eyepiece unit 130 while getting close to the patient. Furthermore, the eyepiece unit 130 according to this modification is provided with two eyepieces 1310a and 1310b. This allows for even higher resolution than the eyepiece unit 13. In this way, the eyepiece optical system according to this modification includes multiple lenses (field lens 1311 and eyepieces 1310a and 1310b) arranged side by side along optical path OR4, which guides image light from the display element 132 to the observer.

[0073] Similar to eyepiece unit 13, eyepiece unit 130 is provided with field lens 1311. Therefore, as already explained, the diameter of eyepieces 1310a and 1310b can be reduced. Furthermore, in eyepiece unit 130, field lens 1311 allows the size of mirror 1315 to be reduced.

[0074] In the modified example, a microscope 10 is assumed to be configured by applying an eyepiece unit 130 instead of the eyepiece unit 13. Up to this point, various design values ​​related to the eyepiece unit 13 have been explained. These design values ​​may be applied to the eyepiece unit 130 related to the modified example as long as no contradictions arise.

[0075] <Other variations> In this embodiment, an example has been shown in which the objective unit 12 and the eyepiece unit 13 are housed in the observation unit 11. However, the observation unit 11 that houses the objective unit 12 and the eyepiece unit 13 does not have to exist. The microscope 10 only needs to have a structure that transmits an image acquired by the objective unit 12 to the eyepiece unit 13.

[0076] Therefore, it is sufficient that the objective unit 12 and the eyepiece unit 13 are connected so as to be able to communicate with each other. In this case, a configuration in which the objective unit 12 and the eyepiece unit 13 communicate directly may be adopted, or a configuration in which the objective unit 12 and the eyepiece unit 13 communicate with each other via the control device 14 may be adopted. The communication method may be wired communication, which uses wiring, or wireless communication, which does not use wiring.

[0077] In this embodiment, various specific examples of design values ​​for the microscope 10 have been described. However, the microscope 10 only needs to have at least a horizontal or vertical pixel count of 2000 or more and 4000 or less for the display element 132 and a viewing angle of 35 degrees or more and 60 degrees or less for the eyepiece optical system 131. Under these conditions, the microscope 10 only needs to adopt at least one of the other design values ​​described in this embodiment.

[0078] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. Note that the configurations exemplified in the present embodiment and the configurations exemplified in the modified examples can be combined as appropriate. [Explanation of symbols]

[0079] 10 microscope, 11, 11a, 11b observation unit, 12, 12a, 12b, 1200 objective unit (photographing device), 13, 13a, 13b, 130, 1300 eyepiece unit, 14 control device, 20 chair unit, 21 treatment chair, 23 foot controller, 27 basin unit, 28 cleaning unit, 29 base, 101 housing, 102 handle, 121, 121a, 121b objective optical system, 122, 122a, 122b imaging element, 131, 131a, 131b eyepiece optical system, 132, 132a, 132b display element, 211 seat, 212 backrest, 213 headrest, 301 pole, 302 arm, 1210 Objective lens, 1220a, 1220b imaging range, 1310, 1310a, 1310b eyepiece lens, 1311 field lens, 1315 mirror, AP eye point, Cr image circle, La, Lb optical axis, Lf1 to Lf3 light beam, OP1 to OP4 light path, SC screen, WS working distance, θc convergence angle, θr chief ray angle, θv field angle.

Claims

1. A diagnostic microscope, an objective optical system; an image sensor that captures an object image formed via the objective optical system; a display element that displays an image acquired by the imaging element; an eyepiece optical system that guides image light from the display element to an observer, the objective optical system includes a first objective optical system and a second objective optical system; the imaging element includes a first imaging element corresponding to the first objective optical system and a second imaging element corresponding to the second objective optical system; the display elements include a first display element corresponding to the first imaging element and a second display element corresponding to the second imaging element; the eyepiece optical system includes a first eyepiece optical system corresponding to the first display element and a second eyepiece optical system corresponding to the second display element; the first objective optical system and the second objective optical system are arranged such that an optical axis of the first objective optical system and an optical axis of the second objective optical system form a convergence angle; the number of horizontal pixels or vertical pixels of the display element is 2000 or more and 4000 or less, A diagnostic microscope, wherein the field of view of the eyepiece optical system is 35 degrees or more and 60 degrees or less.

2. The diagnostic microscope according to claim 1 , wherein the eyepiece optical system includes a plurality of lenses arranged in a line along a light path that guides the image light from the display element to the observer.

3. The plurality of lenses include: An eyepiece and 3. The diagnostic microscope according to claim 2, further comprising a field lens disposed between the display element and the eyepiece.

4. The diagnostic microscope of claim 1 , wherein the ocular optical system includes an ocular lens having a diameter of 60 millimeters or less.

5. the convergence angle is equal to or greater than 4 degrees and equal to or less than 8 degrees, The diagnostic microscope according to any one of claims 1 to 4, wherein the working distance is 250 mm or more.

6. 5. The diagnostic microscope according to claim 1, wherein the eyepiece optical system forms an image circle whose maximum diameter is smaller than the horizontal or vertical width of the display element.

7. The diagnostic microscope according to any one of claims 1 to 4, wherein the chief ray angle of the eyepiece optical system is 1 degree or less.

8. 5. The diagnostic microscope according to claim 1, wherein the eyepiece optical system has an eyepoint of 10 mm or more.

9. 5. The diagnostic microscope according to claim 1, wherein the eyepiece optical system includes a mirror that refracts the image light toward the observer.

10. 5. The diagnostic microscope according to claim 1, wherein the distance between the first objective optical system and the second objective optical system is 25 mm.

Images