JP2019028366A - Imaging optical system and endoscope - Google Patents

Abstract

To provide an imaging optical system that has two focus positions suppressing a falling of image quality by eccentricity, and allowing two images at the two focus positions to be appropriate brightness all together.SOLUTION: An imaging optical system, which can photograph an observation object at a first focus position and at a second focus position serving as a point nearer than the first focus position, has: a transmissivity member 61 that has a transmissivity region serving as a parallel flat plate when photographing the observation object at the first focus position; a stop member 63 when photographing the observation object at the second focus position; and a switch optical member 48 that allows the transmissivity region or the stop member to be arranged in an optical path of the imaging optical system.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an imaging optical system and an endoscope, and more particularly to an imaging optical system and an endoscope having two focus positions.

  Conventionally, there has been an imaging optical system for capturing subject images at two different focal positions. Although two imaging optical systems may be provided to obtain subject images at two different focus positions, there is also one imaging optical system having two different focus positions because the entire imaging optical system becomes large. .

  For example, Japanese Patent Laid-Open No. 2015-134033 proposes an optical unit in which a predetermined optical member for changing the focus position in an endoscope can be arranged on the optical path and retracted from the optical path.

  The optical member is a lens, and is disposed at a predetermined position on the optical path or retracted from the optical path by a driving mechanism. The focus position changes when the lens is disposed on the optical path of the imaging optical system and when the lens is retracted from the optical path.

Japanese Patent Laying-Open No. 2015-134033

  However, in the optical system proposed in the above-mentioned Japanese Patent Application Laid-Open No. 2015-134033, the lens that is an optical member is moved by a mechanical drive mechanism between two positions of an arrangement position and a retracted position. Due to the change, there is a possibility that a deviation occurs between the optical axis of the lens that is moved and the optical axis of the imaging optical system.

  When the optical axis of the arranged lens is deviated from the optical axis of the original imaging optical system and decentration occurs, various optical aberrations occur, and the image quality is deteriorated.

  In addition, when the focus position is changed between the near point and the far point, the light amount from the near point subject and the light amount from the far point subject are different, so at least one of the two images at the two positions is different. In this case, an image with appropriate brightness cannot be obtained.

  Therefore, the present invention provides an imaging optical system and an endoscope having two focus positions that can suppress deterioration in image quality due to decentering and can make two images at two positions have appropriate brightness. The purpose is to do.

  An imaging optical system according to an aspect of the present invention is the imaging optical system capable of imaging an observation target at a first focus position and a second focus position that is closer to the first focus position. A transparent region that is a parallel plate when imaging the observation target at the focus position, and a diaphragm when imaging the observation target at the second focus position, and the optical path of the imaging optical system includes the aperture A transmissive region or an optical member on which the diaphragm can be disposed.

  The endoscope of one embodiment of the present invention has the imaging optical system of the present invention.

  According to the present invention, it is possible to provide an imaging optical system and an endoscope having two focus positions that can suppress deterioration in image quality due to decentering and can make two images at two positions have appropriate brightness. can do.

It is a block diagram which shows the structure of the endoscope apparatus concerning embodiment of this invention. It is sectional drawing of the front-end | tip part 11 of the insertion part 5 concerning embodiment of this invention. It is a perspective view of the switching optical member 48 concerning embodiment of this invention. It is a perspective view of switching optical member 48A concerning the modification of an embodiment of the invention. 1 is a configuration diagram of an imaging optical system of an endoscope when an optical adapter 10 is attached according to an embodiment of the present invention. It is a figure which shows the arrangement | positioning state of the switching optical member 48 in a far point observation state by pressing the focus switching button 6b1 concerning embodiment of this invention. It is a figure which shows the arrangement | positioning state of the switching optical member 48 in the near point observation state by pressing the focus switching button 6b2 concerning embodiment of this invention. It is a figure which shows the optical path in an imaging optical system when the focus position exists in a far point concerning embodiment of this invention. It is a figure which shows the optical path in an imaging optical system when the focus position exists in a near point based on embodiment of this invention. It is a figure for demonstrating the movement of a focus position concerning embodiment of this invention. It is a figure which shows the structure of the imaging optical system which used the meniscus lens for the lens of the most object side of the imaging optical system concerning embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the drawings used for the following description, the scale of each component is made different in order to make each component recognizable on the drawing. It is not limited only to the quantity of the component described in (1), the shape of the component, the ratio of the size of the component, and the relative positional relationship of each component.

  FIG. 1 is a configuration diagram showing a configuration of an endoscope apparatus according to the present embodiment.

  As shown in FIG. 1, the endoscope apparatus 1 includes an apparatus main body 2 having a function such as a video processor, and an endoscope 3 connected to the apparatus main body 2. The apparatus main body 2 includes a display unit 4 such as a liquid crystal panel (LCD) on which an endoscopic image, an operation menu, and the like are displayed. The display unit 4 may be provided with a touch panel.

  The endoscope 3 includes an insertion portion 5 as an endoscope insertion portion that is inserted into a subject, an operation portion 6 that is connected to the proximal end of the insertion portion 5, and a universal cord that extends from the operation portion 6. 7. The endoscope 3 can be attached to and detached from the apparatus main body 2 via a universal cord 7.

  The insertion portion 5 includes a distal end portion 11, a bending portion 12, and a long flexible portion 13 in order from the distal end side. The bending portion 12 is connected to the proximal end of the distal end portion 11, and is configured to be able to bend in the vertical and horizontal directions, for example. The flexible portion 13 is connected to the base end of the bending portion 12 and has flexibility.

  An image pickup device 35 (see FIG. 2) such as a CMOS image sensor is built in the distal end portion 11 of the insertion portion 5. The image sensor 35 receives incident light that has entered the observation window 26 (see FIG. 2) provided at the distal end portion 11 of the insertion portion 5. The imaging optical system has a configuration that can switch between two focus positions.

  As shown by an arrow, the optical adapter 10 can be detachably attached to the distal end portion 11.

  The operation unit 6 is provided with a bending joystick 6a that bends the bending portion 12 in the vertical and horizontal directions. The user can bend the bending portion 12 in a desired direction by tilting the bending joystick 6a. In addition to the bending joystick 6a, the operation unit 6 is provided with buttons for instructing an endoscope function, for example, various operation buttons such as a freeze button, a bending lock button, and a recording instruction button.

  The operation unit 6 is further provided with focus switching buttons 6b1 and 6b2 for acquiring either a far point or a near point image to be described later. When the user of the endoscope presses the focus switch button 6b1, the focus position becomes a far point, and when the focus switch button 6b2 is pressed, the focus position becomes a near point. In the case of a configuration in which the display unit 4 is provided with a touch panel, the user may instruct various operations of the endoscope apparatus 1 including a focus switching operation by operating the touch panel.

  On the display unit 4 of the apparatus main body 2, an endoscopic image captured by the imaging element 35 (see FIG. 2) of the imaging unit provided in the distal end portion 11 is displayed. The apparatus body 2 is provided with various circuits such as a control unit (not shown) that performs image processing and various controls, a recording device that records a processed image in a memory (not shown), and the like.

  FIG. 2 is a cross-sectional view of the distal end portion 11 of the insertion portion 5. FIG. 2 shows a cross section of the insertion portion 5 along the longitudinal axis direction.

  The outer peripheral surface of the insertion portion 5 on the proximal end side of the distal end portion 11 is covered with an outer skin member 21.

  The distal end portion 11 includes a distal end rigid member 22 having a cylindrical shape, and a male screw portion 22 a is formed on the outer peripheral surface of the distal end rigid member 22.

  The columnar optical adapter 10 has a stop ring 10 a that can rotate around the central axis of the insertion portion 5. A female screw portion 10b is formed on the inner peripheral surface of the retaining ring 10a. The optical adapter 10 can be attached to the distal end portion 11 by inserting the distal end rigid member 22 inside the retaining ring 10a and rotating the retaining ring 10a in a predetermined direction. When the retaining ring 10a is rotated in a predetermined direction, the inward flange portion 10c provided at the distal end portion of the retaining ring 10a presses the stepped portion 23a of the adapter body 23 of the optical adapter 10, and the proximal end portion of the adapter body 23 is The step portion 22b of the distal end rigid member 22 is pressed through the O-ring 10d. As a result, the optical adapter 10 is firmly fixed to the distal end portion 11.

  Further, the optical adapter 10 can be detached from the distal end portion 11 by rotating the retaining ring 10a in the direction opposite to the predetermined direction.

  A cover glass 31 is fixed to the tip of the tip hard member 22. Further, three frame members 24a, 24b, 24c are provided in the distal end rigid member 22, and three lenses 32a, 32b, 32c and a cover glass 33 are fixed in the three frame members 24a, 24b, 24c. ing.

  An imaging element 35 having a cover glass 34 fixed on the imaging surface is provided at the base end of the frame member 24c. A signal line inserted into the insertion portion 5 is connected to the image sensor 35.

  A cover member 25 is fixed to the adapter main body 23 so as to cover the distal end surface of the adapter main body 23 of the optical adapter 10.

  A hole 25 a for the observation window 26 and a hole 25 b for the illumination window 27 are formed on the front end surface of the cover member 25.

  A lens 36 is fixed in the hole 25 a of the cover member 25. Further, two frame members 28a and 28b are provided in the adapter main body 23, and two lenses 37a, 37b and 38 and a cover glass 39 are fixed in the two frame members 28a and 28b.

  The lenses 32 a, 32 b, 32 c, 36, 37 a, 37 b, 38 and the cover glasses 31, 33, 39 constitute an imaging optical system of the endoscope 3.

  The lenses 36, 37 a, 37 b, 38 in the optical adapter 10 are attached to the optical adapter 10 so that the optical axis O of the imaging optical system coincides with the optical axis of each lens when the optical adapter 10 is attached to the distal end portion 11. Is provided. The optical axis O passes through the center of the light receiving surface 35a of the image sensor 35 and is orthogonal to the flat light receiving surface 35a.

  A drive mechanism 41 that drives the switching optical member 48 that switches the focus position is provided in the optical adapter 10. The configuration of the drive mechanism 41 will be described later.

  In the distal end portion 11, the distal end portion of the light guide 42 is fixed. The tip surface of the light guide 42 is fixed in close contact with the cover glass 43.

  The optical adapter 10 contains an optical member that receives illumination light from the distal end portion 11 and emits illumination light from the illumination window 27.

  The optical adapter 10 has a rod lens 44 that is an optical member. When the optical adapter 10 is attached to the distal end portion 11, the rod lens 44 is arranged so that the base end surface of the rod lens 44 is disposed at a position for receiving illumination light from the light guide 42 through the cover glass 43. 10 is provided.

  An optical member 45 is disposed on the distal end side of the rod lens 44. A microlens array is formed on one surface of the optical member 45, and the other surface is processed into a ground glass shape. The illumination light emitted from the tip surface of the rod lens 44 is incident on the surface of the optical member 45 on which the microlens array is formed, diffuses on the ground glass surface, and the illumination light without uneven illumination passes through the cover glass 46. Then, the light is emitted from the illumination window 27. The cover glass 46 is fixed to the hole 25 b for the illumination window 27.

  The switching optical member 48 that switches the focus position is driven by a drive mechanism 41 that drives the switching optical member 48. The switching optical member 48 is disposed between the lenses 37b and 38.

  FIG. 3 is a perspective view of the switching optical member 48. The configuration of the switching optical member 48 and the drive mechanism 41 will be described later with reference to FIG.

  As shown in FIG. 3, the switching optical member 48 includes a transmissive member 61 and a diaphragm mounting member 62 in which an opening 62a is formed. The transparent member 61 is made of glass or resin, and is a flat plate member whose front surface and back surface are parallel and has a fan shape. The diaphragm mounting member 62 is made of metal or resin, is a plate-like member having an opening 62a, and has a fan shape. An annular diaphragm member 63 is attached to the diaphragm mounting member 62 with an adhesive or the like so as to cover the opening 62a. The aperture member 63 has an opening 63a. The diaphragm member 63 is made of metal or resin.

  The transmissive member 61 is fixed to the diaphragm mounting member 62 so that the linear section 61 c of the fan-shaped transmissive member 61 is sandwiched and fixed by an adhesive or the like at the linear section 62 c of the diaphragm mounting member 62. .

  A shaft hole 64 is formed in the center of the fan-shaped diaphragm mounting member 62. The shaft member 65 (FIG. 2) is inserted into the shaft hole 64 in a loosely fit state so that the switching optical member 48 can rotate around the shaft hole 64.

  The switching optical member 48 is moved by a drive mechanism 41 that is an electromagnetic actuator.

  Specifically, permanent magnets 66a and 66b are fixed to the linear portion 61d of the fan-shaped transparent member 61 and the linear portion 62d of the fan-shaped diaphragm mounting member 62, respectively, with an adhesive or the like.

  In the optical adapter 10, two coil members 71a and 71b are disposed. The coil member 71a is disposed in the vicinity of the magnet 66a, and the coil member 71b is disposed in the vicinity of the magnet 66b. The coil members 71a and 71b are connected to the four signal lines L inserted into the insertion portion 5 through the contact portion (not shown) when the optical adapter 10 is attached to the distal end portion 11, and the four signals A magnetic field corresponding to the direction of the current flowing through the line L is generated.

  When the far point focus switching button 6b1 is pressed, the coil member 71a generates a magnetic field that pulls the permanent magnet 66a apart, and the coil member 71b generates a magnetic field that pulls the permanent magnet 66b. A drive signal is supplied from the control unit of the main body 2 to the two coil members 71a and 71b via the four signal lines L.

  When the focus switch button 6b2 for the near point is pressed, the coil member 71a generates a magnetic field that attracts the permanent magnet 66a, and the coil member 71b generates a magnetic field that separates the permanent magnet 66b. A drive signal is supplied from the control unit of the apparatus body 2 to the two coil members 71a and 71b via the four signal lines L.

  As described above, the switching optical member 48 selects the transmissive region that is a parallel plate when imaging the far-point observation target that is the first focus position and the near-point observation target that is the second focus position. It is an optical member that has a diaphragm for imaging and can arrange a transmissive region or diaphragm in the optical path of the imaging optical system.

  The optical member may be formed by applying a black paint or the like so as to form a diaphragm opening in a part of a transmissive member such as glass.

  FIG. 4 is a perspective view of the switching optical member 48A according to the modification.

  The switching optical member 48A is configured by applying a black paint 67 to a part of a transmissive member 61A made of fan-shaped glass or resin so as to form a diaphragm opening 62aA. A hatched portion in FIG. 4 indicates a region where the black paint 67 is applied.

  As shown in FIG. 4, permanent magnets 66a and 66b are fixed to two linear portions of the transmissive member 61A with an adhesive or the like.

  FIG. 5 is a configuration diagram of the imaging optical system of the endoscope when the optical adapter 10 is attached. In FIG. 5, the diaphragm member 63 is disposed on the optical path of the imaging optical system.

  In the imaging optical system, the lens 36 is a plano-concave lens, the lens 37a is a convex plano lens, the lens 37b is a plano-concave lens, and a meniscus lens 37 having a convex surface on the object side by joining the lenses 37a and 37b. Composed. The lens 38 is a plano-convex lens. The lens 32a in the distal end portion 11 is a plano-convex lens, the lens 32b is a biconvex lens, and 32c is a concave plano lens. A convex lens is formed by joining the lens 32b and the lens 32c.

  The lenses 38, 32a, 32b, and 32c constitute an imaging optical system. The imaging optical system is disposed on the image side of the switching optical member 48. The most object side lens 38 of the imaging optical system is a positive lens.

  Here, the transmissive member 61 is for a far point, and is used for far point observation, for example, when observing a subject separated from the tip surface of the tip part 11 by a predetermined distance df. The diaphragm member 63 is for near points, and is used for near point observation, for example, when observing a subject separated by a predetermined distance dn from the distal end surface of the distal end portion 11. The distance df and the distance dn have a relationship of dn <df.

  Therefore, the imaging optical system can image the observation target at the first focus position (far point) and the second focus position (near point) that is closer to the first focus position.

  During near-point observation, since the amount of reflected light of the illumination light from the subject is large, the diaphragm member 63 is disposed in the optical path, and the amount of light incident on the image sensor 35 is reduced so that an endoscopic image having a predetermined brightness is obtained. The switching optical member 48 is driven so as to be obtained.

  During far-field observation, since the amount of reflected light of the illumination light from the subject is small, the transmissive member 61 is arranged in the optical path so that the amount of light incident on the image sensor 35 is not reduced, but within a predetermined brightness. The switching optical member 48 is driven so that an endoscopic image is obtained.

  That is, the drive mechanism 41 moves the switching optical member 48 so that the transmissive region of the transmissive member 61 of the switching optical member 48 and the diaphragm member 63 are selectively arranged on the optical path of the imaging optical system.

  When the transmitting member 61 is disposed during far-point observation, the lens frame near the object side of the lens 38 and the outer diameter of the lens 38 act as a substantial brightness stop, although not shown. If the amount of light is sufficient during far-point observation, a circular aperture having a smaller diameter than the lens frame or the lens outer diameter may be arranged. Further, when the amount of light is insufficient, a diaphragm or lens frame having a fan shape or the like may be used so that light is allowed to pass as much as possible without causing flare. In addition, a diaphragm may be provided on the transmissive member 61, and when a far point is observed, if the amount of light transmitted through the transmissive member 61 is insufficient even when a circular diaphragm is provided, as shown by a two-dot chain line in FIG. Alternatively, the metal or resin diaphragm member 61x having the opening 61xa may be fixed to the permeable member 61 with an adhesive or the like. Here, the opening 61xa is formed in a substantially triangular shape in accordance with the shape of the fan-shaped transmissive member 61 so that a larger amount of light can be transmitted than when the shape of the opening 61xa is circular. . If the amount of light is sufficient, a circular diaphragm having a diameter larger than that of the opening 63a may be fixed.

The lens 38 is the most object side lens of the imaging optical system, but the image side surface of the lens 38 is a convex surface 38a. Since the convex surface 38a is separated from the diaphragm member 63, the image height in the imaging optical system can be reduced. Therefore, the diaphragm member 63, that is, the switching optical member 48 can be made small, and as a result, the drive mechanism 41 can be downsized.
(Function)
The user of the endoscope apparatus 1 inserts the insertion portion 5 into the examination target, and while looking at the endoscopic image displayed on the display portion 4 of the apparatus body 2, the distal end portion 11 is brought close to the site to be examined Position and perform endoscopy.

  During the examination, the user can selectively switch the focus position between the far point and the near point by operating the focus switching buttons 6b1 and 6b2.

  6 and 7 are diagrams for explaining the arrangement state of the switching optical member 48 in the distal end portion 11 when the focus position is switched. FIG. 6 is a diagram illustrating an arrangement state of the switching optical member 48 in the far-point observation state when the focus switching button 6b1 is pressed. FIG. 7 is a diagram illustrating an arrangement state of the switching optical member 48 in the near point observation state when the focus switching button 6b2 is pressed.

  As described above, when the user presses the focus switching button 6b1, a magnetic field that causes the coil member 71a to pull away the permanent magnet 66a is generated, and a magnetic field that causes the coil member 71b to attract the permanent magnet 66b is generated. As a result, the transmissive region of the transmissive member 61 is disposed on the optical axis O of the imaging optical system. When the coil member 71b attracts the permanent magnet 66b, a part of the switching optical member 48 comes into contact with the tip part 11 so that the transparent member 61 stops at a predetermined position in the tip part 11. Part 11a is formed.

  When the user depresses the focus switching button 6b2, the coil member 71a generates a magnetic field that attracts the permanent magnet 66a, and the coil member 71b generates a magnetic field that separates the permanent magnet 66b. As a result, the diaphragm member 63 of the diaphragm mounting member 62 is disposed on the optical axis O of the imaging optical system. When the coil member 71a attracts the permanent magnet 66a, the diaphragm mounting member 62 stops at a predetermined position in the distal end portion 11 so that the optical axis O passes through the center of the opening 63a of the annular diaphragm member 63. A contact portion 11 b with which a part of the switching optical member 48 contacts is formed in the distal end portion 11.

  FIG. 8 is a diagram illustrating an optical path in the imaging optical system when the focus position is at a far point.

  As shown in FIG. 8, the transmissive member 61 is disposed on the optical path of the imaging optical system, and as a result, the imaging device 35 can receive a lot of light from the subject.

  FIG. 9 is a diagram illustrating an optical path in the imaging optical system when the focus position is at the near point.

  As shown in FIG. 9, the diaphragm member 63 is disposed on the optical path of the imaging optical system. As a result, the light from the subject is limited by the diaphragm member 63 and is irradiated onto the imaging element 35.

  FIG. 10 is a diagram for explaining the movement of the focus position.

  FIG. 10 shows changes in the focus position when the transmissive member 61 that is a parallel plate is disposed on the optical path of the imaging optical system and when it is retracted from the optical path. A dotted line indicates a light beam during far-point observation, and a one-dot chain line indicates a light beam during near-point observation.

  P1 and P2 indicate the focus positions of the near point and the far point, respectively, when there is no plano-concave lens 36 and meniscus lens 37. P1 is a focus position when the diaphragm member 63 of the switching optical member 48A is disposed in the optical path. P2 is a focus position when the transmissive member 61 of the switching optical member 48A is disposed in the optical path.

  A difference d1 between P1 and P2 on the optical axis O is expressed by the following equation (1).

d1 = (dg / n1) − (dg / n2) (1)
Here, dg is the thickness of the transmissive member 61 along the optical axis O direction, n1 is the refractive index of air, and n2 is the refractive index of the transmissive member 61.

  The focus positions P1 and P2 can be set to desired positions by adjusting the lens system of the entire imaging optical system, the thickness dg of the transmissive member 61, and / or the material of the transmissive member 61.

  That is, by disposing the transmissive member 61 that is a parallel plate in the optical path, the focus position can be changed by the difference d1.

  P3 and P4 indicate the focal positions of the near point and the far point, respectively, when the lens 36, which is a plano-concave lens, is not on the optical path of the entire imaging optical system and the meniscus lens 37 is on the optical path. P3 is a focus position when the diaphragm member 63 of the switching optical member 48A is disposed in the optical path. P4 is a focus position when the transmissive member 61 of the switching optical member 48A is disposed in the optical path.

  The positions of P3 and P4 on the optical axis O and the difference d2 vary depending on the optical characteristics of the meniscus lens 37. In other words, by making the meniscus lens 37 have optical characteristics corresponding to the difference between the far point and the near point focus position required in the imaging optical system from the specifications of the endoscope 3, a desired far point is obtained. The focus position for observation and the focus position for near-point observation can be obtained.

  That is, the meniscus lens 37 has a convex surface on the object side and is arranged on the image side of the switching optical member 48 to change the first focus position at the far point and the second focus position at the near point along the optical path. A variable magnification projection optical system is configured. The optical characteristic of the meniscus lens 37 is a ratio (d2 / d1) between the difference d1 between the far point and the near point focus position without the meniscus lens 37 and the difference d2 between the far point and the near point focus position with the meniscus lens 37. ), It is possible to obtain a desired far point focus position and a desired near point focus position. In other words, the meniscus lens 37 is a variable magnification optical system having a magnification of a ratio (d2 / d1).

  Therefore, the focus positions P3 and P4 required from the specifications of the endoscope 3 are adjusted by adjusting the material of the transmissive member 61 which is a parallel plate and the thickness in the optical axis direction, and the optical characteristics of the meniscus lens 37. Is obtained.

  The lens 36 is disposed on the object side of the meniscus lens 37, which is a variable magnification projection optical system, and has negative power.

  For example, if the power of the lens 36 and the meniscus lens 37 is set so that the difference d2 required in the specification of the endoscope 3 is obtained, it is possible to observe a subject at a desired far point position and near point position. An endoscope 3 can be realized.

  In an endoscope, it is desired to reduce the diameter of the insertion portion. In order to obtain subject images at two different focus positions, it is not preferable to provide two optical systems in the insertion portion because the diameter of the insertion portion is increased.

  Conventionally, in one optical system, a lens for changing the focus position is taken in and out of the optical path. However, if the lens is placed on the optical path or retracted from the optical path, the optical axis of the lens is changed. Is deviated from the optical axis of the imaging optical system, the image quality deteriorates due to the eccentricity of the lens.

  However, according to the above-described embodiment, the optical member that is taken in and out of the optical path is a parallel plate, and therefore it is not necessary to consider the occurrence of deviation of the optical axis.

  Furthermore, the meniscus lens 37 can set the far point and near point focus positions to desired positions.

  As described above, according to the above-described embodiment, imaging having two focus positions that can suppress deterioration in image quality due to eccentricity and that allows two images at two positions to have appropriate brightness. An optical system and an endoscope can be provided.

  The most object side lens 38 of the imaging optical system described above may be a meniscus lens having a concave object side surface and a convex image side surface.

  FIG. 11 is a diagram illustrating a configuration of an imaging optical system in which a lens on the most object side of the imaging optical system is a meniscus lens. In FIG. 11, the lens 38A closest to the object side of the imaging optical system is a meniscus lens.

  The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Endoscope apparatus, 2 Apparatus main body, 3 Endoscope, 4 Display part, 5 Insertion part, 6 Operation part, 6a Curved joystick, 6b1, 6b2 Focus switching button, 7 Universal cord, 10 Optical adapter, 10a ring, 10b Female screw part, 10c inward flange part, 10d ring, 11 tip part, 11a, 11b contact part, 12 bending part, 13 flexible part, 21 outer skin member, 22 tip hard member, 22a male screw part, 22b step part, 23 Adapter body, 23a Stepped portion, 24a, 24b, 24c Frame member, 25 Cover member, 25a, 25b Hole, 26 Observation window, 27 Lighting window, 28a Frame member, 31 Cover glass, 32a, 32b, 32c Frame member, 33 34 Cover glass 35 Image sensor 35a Light receiving surface 36 Lens 37 Meniscus 37a, 37b lens, 38, 38A lens, 38a convex surface, 39 cover glass, 41 drive mechanism, 42 light guide, 43 cover glass, 44 rod lens, 45 optical member, 46 cover glass, 48, 48A switching optical member, 61, 61A Transparent member, 61c, 61d Straight part, 61x Restriction member, 61xa opening, 62 Restriction mounting member, 62a, 62aA Opening, 62c, 62d Straight part, 63 Restriction member, 63a opening, 64 Shaft hole, 65 Shaft member , 66a, 66b Permanent magnet, 67 Paint, 71a, 71b Coil member.

Claims (9)

In an imaging optical system capable of imaging an observation target at a first focus position and a second focus position that is closer to the first focus position,
A transparent region that is a parallel plate when imaging the observation target at the first focus position, and a diaphragm when imaging the observation target at the second focus position, An optical member capable of disposing the transmissive region or the diaphragm in an optical path;
An imaging optical system.   The imaging optical system according to claim 1, further comprising a drive mechanism that moves the optical member so that the transmissive region and the diaphragm are selectively disposed on the optical path of the imaging optical system.   3. The zoom optical system according to claim 1, further comprising a variable magnification projection optical system that is disposed on the image side of the optical member and changes the first focus position and the second focus position along the optical path. Imaging optical system.   The imaging optical system according to claim 3, wherein the variable magnification projection optical system is a meniscus lens having a convex surface on the object side.   The imaging optical system according to claim 3, further comprising a lens that is disposed on the object side of the variable magnification projection optical system and has a negative power.   The imaging optical system according to claim 5, wherein the lens having the negative power is a plano-concave lens.   The imaging optical system according to claim 1, further comprising an imaging optical system disposed on the image side of the optical member.   The imaging optical system according to claim 7, wherein the lens closest to the object side of the imaging optical system is a positive lens.   An endoscope having the imaging optical system according to any one of claims 1 to 8.

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