Optical unit, optical device, and image display system

Abstract

To mitigate observer's discomfort due to contact with a device.SOLUTION: An optical unit 42 comprises: an optical system that has a focal point of an optical incident side at a position in which a display image Im of an object OP is set and emits light from a focal surface as parallel light; and a storage part that accommodates the optical system. When a visible region, in which a display image is visible, is defined as IB, the optical unit is configured to satisfy a conditional expression as shown in IB≥7570 mm3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an optical unit, an optical device, and an image display system.

Background Art

[0002] For the purpose of diagnosing the eye and performing surgical procedures on the eye in ophthalmology, various ophthalmic devices have been realized that enable observation of the eye of a subject (hereinafter referred to as the eye to be examined). As an example of an ophthalmic device, a surgical microscope is known in which a microscope can be freely moved with respect to the eye to be examined, improving the degree of freedom in observing the eye to be examined by an observer (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The first aspect of the present disclosure is an optical system having a focus on the light incident side at a position where a display image of an object is set and emitting light from the focal plane as parallel light, a housing portion that houses the optical system, and when a visible region where the display image can be visually recognized is defined as IB, IB ≧ 7570 mm 3 an optical unit configured to satisfy the conditional expression represented by.

[0005] The second aspect of the present disclosure is an optical system having a focus on the light incident side at a position where a display image of an object is set and emitting light from the focal plane as parallel light, the optical system includes a lens group including a first lens and a second lens, Let the distance from the end of the first lens disposed on the incident side to the end of the second lens disposed on the light emission side be d1, and the distance from the position where the display image is set to the end of the second lens on the light emission side be d2. d1 / d2 > 0.5 It is an optical unit configured to satisfy the conditional expression represented by

[0006] A third aspect of the present disclosure is It includes an optical system having a focal point on the light incident side at the position where the display image of the object is set and emitting light from the focal plane as parallel light. The optical system includes a lens group including a first lens and a second lens. The optical system is an optical unit configured to pass through a position having a diameter larger than 1 / 2 of the effective diameter of the first lens where the principal ray of the maximum angular field of view by the light of the display image is incident.

[0007] A fourth aspect of the present disclosure is An optical device including a plurality of the optical units is provided.

[0008] A fifth aspect of the present disclosure is A left optical system having a focal point on the light incident side at the position where a left-eye display image is set as the display image of the object, emitting light from the focal plane as parallel light, and forming a left-eye visible region where the left-eye display image is visible; A right optical system having a focal point on the light incident side at the position where a right-eye display image different from the left-eye display image is set, emitting light from the focal plane as parallel light, and forming a right-eye visible region where the right-eye display image is visible; A housing portion that houses the left optical system and the right optical system; is provided, In at least one of the left optical system and the right optical system, when the distance from the end of the lens surface on the light incident side to the end of the lens surface on the light emission side is d1, and the distance from the position of the display image to the end of the lens surface on the light emission side is d2, d1 / d2 > 0.5 Configure to satisfy the conditional expression shown by It is an optical device.

[0009] The sixth aspect of the present disclosure is the optical device, a photographing unit that photographs the object, an arm unit on which the photographing unit is arranged, and an image display system including the same.

[0010] The seventh aspect of the present disclosure is a photographing unit that photographs an object, a plurality of optical devices each being the optical device, an installation unit that independently and movably installs each of the plurality of optical devices, and an image display system including the same.

Brief Description of Drawings

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Mode for Carrying Out the Invention

[0012] An example of an embodiment for implementing the technology of the present disclosure will be described below with reference to the drawings. The present disclosure is applicable to any device that displays an image, and is also applicable to a system (for example, an image display system) including a device that displays an image. In the present embodiment, for the sake of simplicity of the following description, a case where the present disclosure is applied to an ophthalmic system in which an observer such as a doctor observes the eye (the eye to be examined) of a patient or the like and the periphery of the eye to be examined for the purpose of ophthalmic diagnosis (or examination) and surgical treatment on the eye (for example, ophthalmic surgery) will be described. In each drawing, the same or equivalent components and parts are given the same reference numerals. Also, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios. In the present embodiment, the eye of a patient or the like is an example of an object.

[0013] The image display system according to the present disclosure is not limited to an ophthalmic system applied to an ophthalmic device. That is, it is not limited to an image display device that displays a captured image by a photographing device that photographs the eye to be examined and the periphery of the eye to be examined for ophthalmic use, but is applicable to an image display device (for example, a medical image display device used for examination or surgery) that photographs an object not limited to ophthalmic use and displays the captured image, and an image display system. For example, in the field of medicine, it is also applicable to an image display device and an image display system used in any branch of medicine (for example, neurosurgery). And it goes without saying that the image display system according to the present disclosure is not limited to an image display device and an image display system used in any branch of medicine, and can be applied to an image display device and an image display system capable of displaying an image. In this specification, "ophthalmology" refers to the branch of medicine that deals with the eye.

[0014] In addition, the image (display image) used in the image display system according to the present disclosure may be a still image or a moving image. Also, the image used in the image display system according to the present disclosure is not limited to a captured image. That is, using an image captured by a photographing device as a captured image is an example of the present disclosure. For example, the present disclosure is also applicable to an image display device and an image display system that display a pre-prepared image.

[0015] As an application example of the ophthalmic system described as an example of the image display system according to the present disclosure, there is a surgical image display system (for example, a system including an ophthalmic surgical microscope) used when an observer such as a doctor observes the eye to be examined and the periphery of the eye to be examined of a patient or the like during a surgical procedure. The application of this ophthalmic surgical microscope is also an example of the image display system according to the present disclosure, and in the field of medicine, it is also applicable to surgical microscopes used in any branch of medicine. And the image display system according to the present disclosure is not limited to surgical microscopes used in the field of medicine, and it goes without saying that it can be applied to other optical devices including microscopes for observing an object.

[0016] FIG. 1 shows an example of the configuration of an ophthalmic system 10 according to an embodiment of the present disclosure. As shown in FIG. 1, the ophthalmic system 10 includes a photographing unit 20 that photographs the eye to be examined and the periphery of the eye to be examined as an object OB, and an image display device 40 that displays the captured image captured by the photographing unit 20 for an observer OP. The image display device 40 includes a display unit 30 such as a liquid crystal or organic EL display that displays the captured image captured by the photographing unit 20, and an optical unit 42 that provides the captured image displayed on the display unit 30 for the observer OP. Note that the image display device 40 in the present embodiment is an example of an optical device including the display unit 30 and the optical unit 42.

[0017] The image display device 40 has a display unit 30 such as a display detachably attached to an optical unit 42. Further, an attachment mechanism 42P is provided in a part on the light incident side of the optical unit 42, and the attachment mechanism 42P is an example of an attachment part for attaching and detaching the display unit to and from the optical unit 42. When the display unit 30 is attached to the optical unit 42, the image display device 40 is formed. The ophthalmic system 10 according to the present embodiment is independently formed of a photographing unit 20 and an image display device 40 including the display unit 30, and the photographing unit 20 and the image display device 40 can be moved separately.

[0018] The ophthalmic system 10 according to the present embodiment will be described by taking as an example the case where an observer OP (for example, a doctor, an assistant, a researcher, etc.) visually observes an eye (the eye to be examined) as an object OB and the periphery of the eye to be examined with both eyes of the observer OP (binocular vision). Note that an example of binocular vision is stereoscopic vision. The ophthalmic system 10 with stereoscopic vision independently forms a right optical path for an image displayed for the right eye of the observer OP and a left optical path for an image displayed for the left eye of the observer OP. For example, the right optical path and the left optical path are arranged to be separated along a predetermined one direction corresponding to the left and right eyes of the observer OP and the eye width direction of the observer OP. Then, when viewed from the observer OP, the right optical path is arranged on the right side and the left optical path is arranged on the left side. In the following description, when distinguishing between the components for the right eye and the left eye, the components for the right eye are denoted by the symbol R, and the components for the left eye are denoted by the symbol L. When distinction is not necessary, the symbols R and L are omitted. Further, in the following description, when the ophthalmic system 10 is installed on a horizontal plane, the eye width direction of the observer OP is defined as the "Y direction", the direction perpendicular to the horizontal plane is defined as the "X direction", and the direction orthogonal to the X direction and the Y direction and in which light travels when the observer OP visually observes an image of the object OB is defined as the "Z direction".

[0019] The imaging unit 20 includes a microscope 22, a camera 24, and a camera controller 26. The microscope 22 includes an optical system for allowing an observer OP or the like to observe the subject eye OB which is the object and the periphery of the subject eye. The camera 24 is an electronic device that converts an image of the subject eye OB and the periphery of the subject eye formed by the microscope 22 into a video signal. The camera controller 26 is an electronic device that converts the video signal into a display signal. The camera controller 26 is connected to the display unit 30 and outputs the display signal to the display unit 30. Thereby, an image captured by the camera 24 is formed as a captured image (display image) Im on the display unit 30.

[0020] In the present embodiment, in order to obtain each of the image to be displayed for the right eye of the observer OP and the image to be displayed for the left eye, the imaging unit 20 includes a right-eye imaging unit 20R and a left-eye imaging unit 20L. Specifically, it includes a right-eye microscope 22R and a left-eye microscope 22L, and a right-eye camera 24R and a left-eye camera 24L. The controller 26 may be configured independently as a right-eye controller 26R and a left-eye controller 26L, or may be configured as a single controller 26. When using a single controller 26, each of the video signals from the right-eye camera 24R and the left-eye camera 24L may be subjected to image processing, and the processed right-eye display signal and left-eye display signal may be output to the right-eye display unit 30R and the left-eye display unit 30L described later. Note that the microscope 22 may be configured to form a parallax image (stereoscopic image) for stereoscopic viewing with a single microscope without including two microscopes (22R, 22L). Also, when not displaying a stereoscopic image, the microscope 22 can display a two-dimensional image of the object OB. Since the imaging unit 20 in the present embodiment has the same configuration for each of the right eye and the left eye, individual descriptions are omitted.

[0021] In the ophthalmic system 10 according to this embodiment, signal transmission and reception (for example, transmission and reception of image data) may be wireless communication or wired communication. For example, communication among the camera 24, the camera controller 26, and the display unit 30 may be wired communication or wireless communication. Note that since the display unit 30 has the same configuration for each of the right eye and the left eye, individual descriptions are omitted. The observer OP operates the microscope 22 to set the observation position of the subject eye OB as the object and the periphery of the subject eye.

[0022] The optical unit 42 included in the image display device 40 is an example of the optical unit of the present disclosure, and is an optical system that functions as an objective lens that at least refracts and emits the light incident from the captured image Im (details will be described later). Note that the optical unit 42 is an example of the optical system of the present disclosure, has a focal point on the light incident side at the position where the captured image (display image) Im of the object is set, and emits the light from the focal plane (in this case, the captured image Im or the plane on which the captured image Im is arranged) as parallel light. This optical unit 42 can include at least one doublet lens. The image display device 40 is attached to a pedestal (not shown), is formed independently of the imaging unit 20, and is formed non-contact with respect to the observer OP. By forming the image display device 40 non-contact with respect to the observer OP, the discomfort of the observer OP caused by the contact of the observer OP with the image display device 40 is suppressed.

[0023] The ophthalmic system 10 according to this embodiment is configured such that the imaging unit 20 and the image display device 40 are formed separately and independently, and each can be moved separately. Therefore, even when the observer OP moves the imaging unit 20 to change the observation position while visually observing the object OB (for example, the eye to be examined and the periphery of the eye to be examined) with the image display device 40, the image display device 40 (for example, the display unit 30) does not move. Thus, the observer OP can visually observe the captured image Im without moving the head. This is effectively applicable when, for example, an operating microscope for ophthalmic surgery is applied to the imaging unit 20. For example, when performing a surgical procedure while moving the surgical field, the observer OP, such as a doctor, can concentrate on the surgery while visually recognizing the surgical field without changing the visual position. Also, by enabling the imaging unit 20 and the image display device 40 to be formed independently, the imaging unit 20 only needs to be able to capture the object OB, and the degree of freedom in the shape of the imaging unit itself is increased.

[0024] In addition, the ophthalmic system 10 according to this embodiment can suppress visual observation of the image display device 40 by the observer OP in an unnatural posture. For example, it becomes possible to observe at an optimal position regardless of the height of the observer OP. In addition, the ophthalmic system 10 according to the present embodiment functions effectively when a plurality of observers OP, such as an operator and an assistant, visually observe an object OB (for example, the eye to be examined and the periphery of the eye to be examined). That is, as the ophthalmic system 10 according to the present embodiment, at least a plurality of image display devices 40 are provided, the imaging unit 20 and each of the plurality of image display devices 40 are formed independently and separately, and each separate observer OP can effectively function when visually observing the same captured image or each captured image of the object OB with each image display device 40. For example, it is considered that the operator and the assistant visually observe the same part of the object OB in a seated state (seated position) on a chair or the like, but the operator is mainly responsible for specifying and moving the part where the object OB is visually observed. However, when the ophthalmic system 10 is integrally formed, when the operator moves a microscope or the like when specifying or moving the part to be visually observed, the assistant also needs to move as the operator moves. For example, when the operator moves a microscope or the like in the X direction (the direction away from the object OB) during the observation of the object OB, the assistant may come into contact with the eyepiece part being pressed due to an unexpected movement. On the other hand, in the ophthalmic system 10 according to the present embodiment, the imaging unit 20 and the image display device 40 are formed independently and separately and can be independently moved. Therefore, without worrying about unexpected movements in the ophthalmic system 10, the operator can concentrate on the treatment and the assistant can concentrate on the observation.

[0025] FIG. 24 shows an example of the configuration of an ophthalmic system including an image display device according to the present embodiment. In the example shown in FIG. 24, as the ophthalmic system 10, a display image of the object OB (for example, the eye to be examined and the periphery of the eye to be examined) photographed by the photographing unit 20 is displayed on the 3D display device 30-1, which is a display, for the observer OP (here, the surgeon OP1 as the first user) who visually observes while performing the treatment in a seated state. The 3D display device 30-1 displays a display image that presents a stereoscopic image to the surgeon OP1 using the right-eye image (right-eye display image) and the left-eye image (left-eye display image) of the object OB photographed by the photographing unit 20 with parallax. Note that the present disclosure is not limited to stereoscopic display, and a two-dimensional image of the object OB photographed by the photographing unit 20 may be displayed as it is. Also, the same display image as the display image viewed by the surgeon OP1 is displayed on the display unit 30 attached to the image display device 40 for another observer OP (here, the assistant OP2 as the second user) who visually observes in a seated state.

[0026] The photographing unit 20 is disposed on the arm portion 29A attached to the base portion 28 and can be freely moved by the operation of the surgeon OP1. The 3D display device 30-1 is installed in front of the surgeon OP1 (in the Y direction in FIG. 24) so that its position can be adjusted. Also, the image display device 40 is installed on the installation portion 29B attached to the base portion 28 so as to be movable along with the movement of the head of the assistant OP2, and can be freely moved in each of the up, down, left, right, front, and rear directions by the operation of the assistant OP2. Thus, the photographing unit 20 and the image display device 40 can move independently. The arm portion 29A is an example of the arm portion of the present disclosure, the installation portion 29B is an example of the installation portion of the present disclosure, and the base portion 28 is an example of the base portion to which the arm portion 29A and the installation portion 29B are attached. In the example shown in FIG. 24, an example of attaching the arm portion 29A and the installation portion 29B to the base portion 28 is shown, but the arm portion 29A and the installation portion 29B may be configured to be independent from the ground surface or the like.

[0027] In the example shown in FIG. 24, on the base portion 28, displays 30-2 and 30-3 different from the 3D display device 30-1 are arranged. The same display image as the display image viewed by the operator OP1 can be displayed on the displays 30-2 and 30-3. For example, on the display 30-2, a display image for presenting a stereoscopic image to the operator OP1 can be converted into a two-dimensional image (for example, an image for the right eye or an image for the left eye) and displayed, or a part of the image displayed on the 3D display device 30-1 can be enlarged and displayed. Further, on the display 30-3, a display image for presenting a stereoscopic image for the assistant OP2 can be displayed. Further, on the display 30-3, the display image presented to the operator OP1 or the assistant OP2 can be displayed for other observers OP (here, the trainee OP3 as the third user).

[0028] In the ophthalmic system 10 configured in this way, since the imaging unit 20 and the image display device 40 are formed independently and separately and can be independently moved, the operator can concentrate on the operation and the assistant can concentrate on the observation.

[0029] Note that the 3D display device 30-1 may be installed via the base portion 28. In the example shown in FIG. 24, the display image is displayed for the operator OP1 by the 3D display device 30-1 and for the assistant OP2 by the image display device 40, but the reverse may also be true.

[0030] Further, the positions of the operator OP1 and the assistant OP2 are not limited to the positions shown in FIG. 24. For example, when performing an operation on the side portion of the patient's head with the patient lying on their back as the object OB (ear-side incision), the operator OP1 may be in the position of the assistant OP2 shown in FIG. 24, and the assistant OP2 may be in the position of the operator OP1 shown in FIG. 24. In this case, the operator OP1 may view the 3D display device 30-1 whose position is adjusted in front of the operator OP1 (the direction opposite to the Z direction in FIG. 24) or view the display 30-3. On the other hand, since the image display device 40 for displaying an image to the assistant OP2 can be freely moved by the operation of the assistant OP2, the assistant OP2 may move the image display device 40 so that the assistant OP2 can view the image in the position of the operator OP1 shown in FIG. 24.

[0031] Furthermore, the observer OP who visually observes the image in the ophthalmic system 10 is not limited to the two persons of the operator OP1 and the assistant OP2. For example, there may be three or more persons. For example, consider a case where the operation is performed by three persons with one operator OP1 and two assistants OP2. In this case, for example, it is conceivable that the operator OP1 performs the operation at the position of the operator OP1 shown in FIG. 24, and the two assistants OP2 assist at the positions on both sides of the operator OP1. In this case, the operator OP1 performs the operation while visually observing the 3D display device 30-1 which is the front monitor, the assistant OP2 at the position shown in FIG. 24 visually observes the display 30-3 or the image display device 40, and the assistant at the position opposite to the assistant OP2 at the position shown in FIG. 24 may visually observe the image display device 40.

[0032] FIG. 25 shows another example of the configuration of the ophthalmic system provided with the image display device according to the present embodiment. In the example shown in FIG. 25, the ophthalmic system 10 includes a plurality of image display devices 40-1 and 40-2. The image display device 40-1 displays a display image for the operator OP1, and the image display device 40-2 displays a display image for the assistant OP2. The imaging unit 20 is disposed on an arm portion 29A attached to the base portion 28 and is movable freely by the operation of the operator OP1. In the example shown in FIG. 25, the image display devices 40-1 and 40-2 are disposed for each of the operator OP1 and the assistant OP2. The image display device 40-1 is installed in an installation portion 29C attached to the base portion 28 so as to be movable along with the movement of the head of the operator OP1, and is movable freely in each of the vertical, horizontal, front, rear, left, and right directions by the operation of the operator OP1. Further, the image display device 40-2 is installed in an installation portion 29B attached to the base portion 28 so as to be movable along with the movement of the head of the assistant OP2, and is movable freely in each of the vertical, horizontal, front, rear, left, and right directions by the operation of the assistant OP2. Thereby, the imaging unit 20 and the image display devices 40-1 and 40-2 are movable independently. Further, each of the image display devices 40-1 and 40-2 is movable independently. Thus, since each of the imaging unit 20 and the image display device 40 (in this case, the image display devices 40-1 and 40-2) is formed independently and separately and is movable independently, the operator can concentrate on the surgery and the assistant can concentrate on the observation. In the example shown in FIG. 25, an example in which the arm portion 29A, the installation portion 29B, and the installation portion 29C are attached to the base portion 28 is shown, but the arm portion 29A, the installation portion 29B, and the installation portion 29C may be configured to be independent from a ground surface such as the ground.

[0033] Fig. 2 shows an example of the configuration of the image display device 40. In Fig. 2, the image display device 40 is shown in a top view, and an example is shown in which the optical units 42 independent for the right eye and the left eye of the observer OP are arranged. The optical unit 42 includes an optical unit 42R for the right eye, which is an example of the right optical system, and an optical unit 42L for the left eye, which is an example of the left optical system. The optical unit 42R for the right eye and the optical unit 42L for the left eye are respectively arranged along a direction corresponding to the eye width direction (e.g., the Y direction in Fig. 2) of both eyes of the observer OP. Note that the optical unit 42R for the right eye and the optical unit 42L for the left eye may be respectively arranged along a direction corresponding to the parallax direction in which the observer OP wants to create a parallax. For example, the optical unit 42R for the right eye and the optical unit 42L for the left eye are arranged to be separated along a predetermined one direction corresponding to the left and right eyes of the observer OP and the eye width direction of the observer OP. And when viewed from the observer OP, the optical unit 42R for the right eye is arranged on the right side, and the optical unit 42L for the left eye is arranged on the left side. Further, the optical unit 42R for the right eye includes a display unit 30R for the right eye on the optical unit 42R for the right eye, and a right mounting mechanism 42PR as an example of a mounting part on the light incident side of the optical unit 42R for the right eye, and the optical unit 42L for the left eye includes a display unit 30L for the left eye on the optical unit 42L for the left eye, and a left mounting mechanism 42PL as an example of a mounting part on the light incident side of the optical unit 42L for the left eye.

[0034] As shown in FIG. 2, the image display device 40 forms an image (a right-eye display image which is an example of a right-side display image) captured by the imaging unit 20R for the right eye, which is an example of the right-side imaging unit, as a captured image ImR on the display unit 30R, and provides it to the right eye of the observer OP via the optical unit 42R for the right eye. Further, an image (a left-eye display image which is an example of a left-side display image) captured by the imaging unit 20L for the left eye, which is an example of the left-side imaging unit, is formed as a captured image ImL on the display unit 30L, and provided to the left eye of the observer OP via the optical unit 42L for the left eye. These optical units 42R for the right eye and 42L for the left eye are housed in a housing case 41 that shields external light (e.g., noise light) incident from outside the optical paths of the optical unit 42. Further, the housing case 41 is an example of a housing unit that houses and fixes the optical unit 42R for the right eye and the optical unit 42L for the left eye, and can fix the optical unit 42R for the right eye and the optical unit 42L for the left eye such that their respective optical axes are parallel to each other. The housing case 41 may be composed of a first housing case that houses each of the optical unit 42R for the right eye and the optical unit 42L for the left eye independently, and a second housing case that houses the first housing case.

[0035] In addition, the right-eye optical unit 42R and the left-eye optical unit 42L of the image display device 40 have pupils. That is, the optical unit 42R and the left-eye optical unit 42L form pupils on the light emission side. The pupil has an entrance pupil and an exit pupil. The image display device 40 forms the entrance pupil InpR for the right eye of the right-side optical system and the entrance pupil InpL for the left eye of the left-side optical system on the light emission side of the light of the image display device 40 in the optical path outside the optical system, that is, in front of the observer OP. In the following description, when there is no need to distinguish between the right-eye entrance pupil InpR and the left-eye entrance pupil InpL, they are collectively referred to as "entrance pupil Inp" (see FIGS. 9A and 9B). Further, the image display device 40 forms the exit pupil ExpR for the right eye and the exit pupil ExpL for the left eye on the light emission side of the light of the image display device 40 in the optical path outside the optical system, that is, in front of the observer OP. In the following description, when there is no need to distinguish between the right-eye exit pupil ExpR and the left-eye exit pupil ExpL, they are collectively referred to as "exit pupil Exp" (see FIGS. 9A and 9B).

[0036] The ophthalmic system 10 according to the present embodiment can display different right-eye captured images ImR and left-eye captured images ImL corresponding to parallax in a space (for example, a visible region described later), and the observer OP can visually recognize the object OB as a stereoscopic image by viewing with the right eye and the left eye.

[0037] Here, the image display device 40, which is formed independently of the imaging unit 20 and is formed in a non-contact manner with respect to the observer OP, can suppress the discomfort of the observer OP caused by the contact of the observer OP with the image display device 40 as the distance from the observer OP increases. However, generally, as the distance between the image display device 40 and the observer OP increases, the captured image Im visible to the observer OP becomes smaller. That is, within the visible range covering the entire angular field of view of the light emitted from the optical unit 42, which is known as the so-called eye point, the captured image Im is visible. On the other hand, when the viewing position of the observer OP deviates from the eye point, at least a part of the angular field of view of the light emitted from the optical unit 42 does not reach the observer OP. In this case, since a state occurs in which at least a part of the angular field of view of the light is blocked, the observer OP cannot see the entire image of the object OB. Therefore, by increasing the eye point, it is possible to contribute to the improvement of suppressing the discomfort of the observer OP caused by the contact of the observer OP with the image display device 40 or to the expansion of the observation area where the appearance of the image does not change. Therefore, in the present embodiment, an optical unit 42 capable of increasing the eye point is provided.

[0038] Note that the light emitted from the optical unit 42 is a rotationally symmetric light beam with the optical axis of the optical unit 42 as its axis. Therefore, the visible range that covers the entire angular field of view of the light emitted from the optical unit 42, which is the eye point, is a substantially conical region with the optical axis of the optical unit 42 as its axis. In the present embodiment, a substantially conical region with the optical axis of the optical unit 42 as its axis, which is the visible range that covers the entire angular field of view of the light emitted from the optical unit 42, is referred to as the eye box region. For example, the eye box region is formed on the light emission side of the optical unit 42 (or in front of the observer OP) and is a visible region formed by a group of positions where an image can be visually observed in a predetermined space. Further, the eye box region includes a region where the appearance of the display image (in this case, the photographed image Im) does not change as long as the eye of the observer OP is placed within that region in space. When the optical unit 42 is configured by an afocal optical system described later, an example of the appearance of the display image is the size of the image. Furthermore, the eye box region includes a region where the observation range does not change as long as the eye is placed within that region in space.

[0039] The eye box region, which is a visible region where the observer OP can visually observe the display image, can be derived based on the lens system included in the optical unit 42 and the angle formed by the chief ray of the maximum angular field of view and the optical axis of the optical unit 42. Note that the chief ray of the maximum angular field of view is the chief ray emitted from the maximum object height of the display image and is also the chief ray of the irradiation expected angle.

[0040] Fig. 3 shows the relationship between the lens Le arranged on the observer side among the lens groups of the optical unit 42 and the eye of the observer OP. As shown in Fig. 3, let the angle that is the semi-angular field of view (the angle formed by the chief ray of the maximum angular field of view and the optical axis) be ω (hereinafter, may be referred to as the angular field of view), the eye relief be ER, and the eye point diameter be φ EP , then the visible region (hereinafter, referred to as the eye box region) IB where the observer OP can visually observe the display image, which is the eye box region, can be expressed by the following formula. IB = {(φ EP / 2) / tan ω + ER} · {(φ EP / 2)+ER·tanω} 2 ·π·(1 / 3)

[0041] The half field angle ω is the angle formed by the light ray reaching the observer OP's eye from the lens Le of the optical unit 42 closest to the observer OP's eye in the lens group of the optical unit 42 (for example, the lens located on the outermost surface on the light emission side of the optical unit 42) and the optical axis CL. Also, the eye relief ER is the distance from the vertex of the lens Le to the vertex of the assumed observer OP's eye (eye point). Also, the eye point diameter φ EP is the length of the region where all the light rays emitted from the lens Le reach the observer OP's eye when the observer OP moves the eye in one direction (for example, up and down) at the position of the eye relief ER.

[0042] Also, when the effective diameter of the lens Le of the optical unit 42 closest to the observer OP's eye is φ LS , the eye box region IB can also be expressed by the following formula. IB=(π / 3)·(φ LS / 2) 2 ·{(φ LS / 2) / tanω}

[0043] Here, the eye box region IB that depends on the effective diameter φ LS of the lens on the observer OP's eye side in the lens group of the optical unit 42 and the half field angle ω of the light emitted from the optical unit 42 will be described.

[0044] In FIG. 4, an example of the relationship between the effective diameter φ LS of the lens on the observer OP's eye side and the eye box region IB that depends on the half field angle ω of the light emitted from the optical unit 42 is shown. In FIG. 4, as the field angle ω, the half field angle (ω) indicating the angle formed by the optical axis CL of the optical unit 42 and the light emitted from the optical unit 42 is used.

[0045] As shown in FIG. 4, for example, in order to obtain an eye box region IB of 10000 mm 3 or more, with the curve Cv1 shown in FIG. 4 as the boundary, 10000 mm 3The effective diameter φ that becomes the above-mentioned inbox area IB LS and the half angular width ω (in the example shown in FIG. 4, the relationship included in the area AR-Y indicating the right area in the figure with the curve Cv1 as the boundary) to form the optical unit 42. On the other hand, in the optical unit 42 of the relationship included in the area AR-X indicating the left area in the figure with the curve Cv1 as the boundary in the example shown in FIG. 4, 10000 mm 3 or more of the inbox area IB is difficult to obtain. Also, for example, 20000 mm 3 or more of the inbox area IB, in order to obtain, with the curve Cv3 shown in FIG. 4 as the boundary, 20000 mm 3 The effective diameter φ that becomes the above-mentioned inbox area IB LS and the half angular width ω (in the example shown in FIG. 4, the relationship included in the area AR-Y indicating the right area in the figure with the curve Cv3 as the boundary) to form the optical unit 42. Similarly, for 30000 mm 3 or more of the inbox area IB, in order to obtain, with the curve Cv4 shown in FIG. 4 as the boundary, 30000 mm 3 The effective diameter φ that becomes the above-mentioned inbox area IB LS and the half angular width ω (in the example shown in FIG. 4, the relationship included in the area AR-Y indicating the right area in the figure with the curve Cv4 as the boundary) to form the optical unit 42, and for 40000 mm 3 or more of the inbox area IB, in order to obtain, with the curve Cv5 shown in FIG. 4 as the boundary, 40000 mm 3 The effective diameter φ that becomes the above-mentioned inbox area IB LS and the half angular width ω (in the example shown in FIG. 4, the relationship included in the area AR-Y indicating the right area in the figure with the curve Cv5 as the boundary) to form the optical unit 42.

[0046] Next, consider each of the effective diameter φ of the lens on the observer OP's eye side LS and the half angular width ω of the light emitted from the optical unit 42.

[0047] In the ophthalmic system 10 according to this embodiment, since the observer OP views the object OB with both eyes, the distance between the optical axis of the left-eye optical unit 42L and the optical axis of the right-eye optical unit 42R corresponds to the interpupillary distance, i.e., the eye width (Pupil Distance) PD of both eyes, of the observer OP. Statistically, the human eye width PD is distributed in the range of 41 mm to 73 mm. Therefore, considering that the eye width PD has a central value of 57 mm and assuming a standard pupil diameter of 2 mm, if the eye-point diameter φ EP is set to 18 mm, almost all eye widths PD can be covered. Also, assuming a standard eyeball diameter of 24 mm and ensuring visibility even within a range of 30 degrees of rotation, if the eye-point diameter φ EP is set to 30 mm, light can enter the eyes of almost all observers OP. Further, considering that the eyelashes of the observer OP may contact the lens on the eye side, the eye relief ER is preferably 15 mm or more. And the semi-field angle of a standard microscope eyepiece lens is 20 degrees. From the above, the effective diameter φ LS of the lens on the eye side of the observer OP is preferably at least 41 mm as the minimum value.

[0048] Although the information discrimination ability is low, when assuming a field of view as the region that affects the subjective spatial coordinate system, for example, when assuming a field of view that creates a sense of immersion, it is preferable to set the semi-field angle to ±50 degrees or less. Setting the semi-field angle to ±50 degrees or less can cover the induction field of view known as the region that affects the subjective spatial coordinate system. Also, when assuming the stable fixation field of view known as the region where the eyes and head can be fixated without difficulty during eye and head movements and effective information reception is possible, it is preferable to set the semi-field angle to ±45 degrees or less. Further, when assuming the effective field of view known as the region where information can be received instantaneously only by eye movement, it should include at least ±15 degrees in terms of the semi-field angle. Furthermore, when assuming the discrimination field of view known as the central visual region with excellent visual functions such as visual acuity, it should include at least ±2.5 degrees in terms of the semi-field angle.

[0049] Therefore, when assuming the induction field of view as described above, it is preferable to set the semi-field angle ω to ±50 degrees or less. That is, the eye box region IB is ω ≤ 50 degrees It is preferable to configure the optical unit 42 so as to satisfy the conditions indicated by .

[0050] In this case, for the effective diameter φ of the lens on the observer OP's eye side LS The eye box region IB formed by the light emitted by the optical unit 42 with an effective diameter φ of 41 mm and a half field angle ω of 50 degrees is obtained by substituting φ LS = 41 and ω = 50 into the above formula, resulting in approximately 7570 mm 3 (for example, the intersection point ST in FIG. 4). Thus, if the optical unit 42 is configured such that the eye box region IB is 7570 mm 3 or more, substantially all observers OP can visually observe the display image (for example, the captured image) within the guiding visual field, and the image display device 40 can be formed without the observer OP coming into contact with the optical unit 42. For example, as shown in FIG. 4, to obtain an eye box region IB of 7570 mm 3 or more, with the curve Cv2 shown in FIG. 4 as the boundary, an optical unit 42 having a relationship between the effective diameter φ 3 and the half field angle ω such that the eye box region IB is 7570 mm LS or more (in the example shown in FIG. 4, the relationship included in the area AR-Y indicating the right side region in the figure with the curve Cv2 as the boundary) may be formed.

[0051] Based on the above, it is preferable to form the optical unit 42 in the present embodiment using the following design conditions. The first design condition is that the eye box region IB satisfies IB ≥ 7570 mm 3 That is, the optical unit 42 (optical unit 42R and optical unit 42L) is configured to satisfy the first conditional expression indicated by .

[0052] Also, for example, assuming the eye width PD of an adult, the effective diameter φ of the lens on the observer OP's eye side in the above first design condition LS can be 53.5 mm or more, and 7570 mm in the first conditional expression 3 is 16800 mm3 can be replaced with That is, the eye box area IB is IB≧16800mm 3 It is also possible to configure the optical unit 42 so as to satisfy the extended first conditional expression represented by

[0053] Also, when assuming a stable fixation field of view as described above, it is preferable that the half angle be ±45 degrees or less. In this case, the effective diameter φ of the lens on the observer OP's eye side LS is 41 mm, and the eye box area IB formed by the light emitted by the optical unit 42 with a half angle ω of 45 degrees is obtained by substituting φ LS = 41 and ω = 45 into the above formula, which is approximately 9000 mm 3 Accordingly, if the optical unit 42 is configured such that the eye box area IB is 9000 mm 3 or more, substantially all observers OP can visually observe the display image (for example, a photographed image) within the stable fixation field of view, and the image display device 40 can be formed without the observer OP coming into contact with the optical unit 42.

[0054] Based on the above, when assuming a stable fixation field of view, the optical unit 42 in the present embodiment is preferably formed using the following design conditions. The first design condition is that the eye box area IB is IB≧9000mm 3 The optical unit 42 (optical unit 42R and optical unit 42L) may be configured so as to satisfy the first conditional expression represented by

[0055] Also, for example, when assuming a stable fixation field of view and the interpupillary distance PD of an adult, the effective diameter φ of the lens on the observer OP's eye side LS can be 53.5 mm or more, and 9000 mm in the first conditional expression 3 can be replaced with 20000 mm 3 can be replaced with That is, the eye box area IB is IB≧20000mm 3 It is also possible to configure the optical unit 42 so as to satisfy the expanded first conditional expression expressed as follows:

[0056] By the way, the half angle of view ω of a typical microscope is 20 degrees or more, and the effective diameter φ of the lens on the eye side of the observer OP is LS When the focal length is 41 mm, the eye box area IB formed by the light emitted by the optical unit 42 is calculated by adding φ LS Substituting =41 and ω=20, it comes to about 24,800 mm. 3 This results in an eye box area IB of 24800 mm. 3 If the optical unit 42 is configured as described above, it is possible to form an image display device 40 in which almost all observers OP can view a displayed image (e.g., a photographed image) while ensuring a field of view equivalent to that of a general microscope, and in which the observer OP does not come into contact with the optical unit 42. Furthermore, assuming an interpupillary distance PD of an adult, the effective diameter φ of the lens on the eye side of the observer OP can be set to LS If the focal length is 53.5 mm, the eye box area IB is 55000 mm according to the above formula. 3 become.

[0057] Therefore, the eye box area IB is IB≧24800mm 3 It is also possible to configure the optical unit 42 so as to satisfy the further expanded first conditional expression expressed as follows: Also, preferably, the eye box region IB is IB≧55000mm 3 It is also possible to configure the optical unit 42 so as to satisfy the expanded first conditional expression expressed as follows:

[0058] Here, without changing the half angle of view (ω=20 in this case), the effective diameter φ of the lens on the eye side of the observer OP is changed. LS The presence or absence of eye rotation is considered in the above discussion. Eye rotation includes the range of movement of the eye due to eye movement. When the rotation is visible within the range of ±15 degrees, the effective diameter φ LS becomes 35.2 mm, and the eye box area IB is 15700 mm 3 This is the case. Thus, when assuming a rotation of ±15 degrees and considering the freedom of the observer OP's head, the eye box area IB is preferably 15700 mm 3 or more. Therefore, the eye box area IB is IB ≧ 15700 mm 3 It is also possible to configure the optical unit 42 so as to satisfy the extended first conditional expression represented by Incidentally, when the rotation is visible within the range of ±20 degrees, the effective diameter φ LS becomes 37.2 mm, and the eye box area IB is 18500 mm 3 This is the case. Also, when the rotation is visible within the range of ±30 degrees, the effective diameter φ LS becomes 41 mm, and the eye box area IB is 24800 mm 3 This is the case. Therefore, the eye box area IB is included in the condition that it is 15700 mm 3 or more.

[0059] By the way, in an optical device such as a microscope observed by the observer OP, the viewing angle is 11 degrees or more. Assuming a standard interpupillary distance PD, the effective diameter φ of the lens on the observer OP's eye side LS is preferably allowed to be up to about 65 mm in size. In this case, it is considered that the function of the image display device 40 of the present disclosure can be achieved by allowing the eye box area IB to be up to about 185000 mm 3 in size. That is, the eye box area IB is IB ≦ 185000 mm 3 It is preferable to configure the optical unit 42 so as to satisfy the conditional expression indicating the upper limit value represented by

[0060] By the way, the statistically average interpupillary distance PD is 65 mm. Thereby, the effective diameter φ of the lens on the observer OP's eye sideLS Preferably, the maximum value is 65 mm. The second design condition is the effective diameter φ of the lens on the observer OP's eye side LS is φ LS ≦65 mm The optical unit 42 is configured to satisfy the second conditional expression represented by this.

[0061] Also, as described above, it is preferable that the minimum value of the effective diameter φ of the lens on the observer OP's eye side is 41 mm. LS is 41 mm. The third design condition is the effective diameter φ of the lens on the observer OP's eye side LS is φ LS ≧41 mm The optical unit 42 is configured to satisfy the third conditional expression represented by this.

[0062] In addition, when the eye width PD or the effective diameter φ of the lens LS is large, the eye box region IB is preferably formed in a large region. In this case, in order to obtain an eye box region IB of 10,000 mm 3 or more, for example, the optical unit 42 is formed in the relationship between the effective diameter φ LS and the half angle ω so as to be included in the area AR-Y showing the right side region in the figure with the curve Cv1 shown in FIG. 4 as a boundary. Also, in order to obtain an eye box region IB of 20,000 mm 3 or more, the optical unit 42 is formed in the relationship between the effective diameter φ LS and the half angle ω so as to be included in the area AR-Y showing the right side region in the figure with the curve Cv3 shown in FIG. 4 as a boundary. Further, in order to obtain an eye box region IB of 30,000 mm 3 or more, the optical unit 42 is formed in the relationship between the effective diameter φ LS and the half angle ω so as to be included in the area AR-Y showing the right side region in the figure with the curve Cv4 shown in FIG. 4 as a boundary. In order to obtain an eye box region IB of 40,000 mm 3 or more, the optical unit 42 is formed in the relationship between the effective diameter φLS An optical unit 42 that has a relationship with the semi-horizontal viewing angle ω may be formed.

[0063] The eye box region IB, which is a visible region, can be derived based on the effective diameter of the lens included in the optical unit 42 (the right-eye optical unit 42R and the left-eye optical unit 42L) and the angle formed by the chief ray of the maximum viewing angle and each optical axis of the optical unit 42 (the right-eye optical unit 42R and the left-eye optical unit 42L). In this case, the eye box region IB, which is a visible region, is preferably formed so as to satisfy the condition that the semi-horizontal viewing angle ω is 50 degrees or less (ω≦50).

[0064] Fig. 5 schematically shows the relationship between the display unit 30 and the optical unit 42 when the observer OP views the display unit 30 binocularly. Since the relationships for the optical paths of the left and right eyes are the same, in Fig. 5, the relationship for the optical path of the right eye eyeR, which is an example of the right-side optical path, is described with reference numerals, and the description of the relationship for the optical path of the left eye eyeL, which is an example of the left-side optical path, is omitted.

[0065] Considering that the eye width PD, which is the interpupillary distance of the observer OP, is typically from 60 mm to 70 mm, the maximum diameter of the inscribed circle MD of the display unit 30 corresponding to the optical path of each of the left and right eyes when viewing an object with both eyes is from 60 mm to 70 mm. Here, it is known that there are asymmetric aberrations that do not exist in the on-axis light for the off-axis light. However, for example, when a lens is arranged in a region where the on-axis light and the off-axis light overlap, it is difficult to correct the aberrations specific to the off-axis light with the arranged lens. Therefore, as shown in FIG. 5 of the present embodiment, by arranging the lens of the optical unit 42 (for example, the lens Lf shown in FIG. 9A described later) in a region where the on-axis light (for example, the chief ray of the on-axis light) and the off-axis light (for example, the chief ray of the off-axis light) do not overlap and the ray interval between the on-axis light and the off-axis light is wide, the aberrations can be corrected. Also, as shown in FIG. 5, the on-axis light JI and the off-axis light JE separate as they approach the display unit 30 from the lens surface of the optical unit 42. Considering these matters, as a result of conducting various experiments to study the enlargement of the eyebox region, the distance from the lens surface closest to the eye of the optical unit 42 (for example, the lens surface on the eye side of the lens Le shown in FIG. 9A described later) to the end of the lens surface closest to the display unit 30 (for example, the lens surface on the display unit 30 side of the lens Lf shown in FIG. 9A described later) is set to a distance that exceeds twice the distance d2 from the lens surface closest to the eye to the display unit 30. In this way, the optical unit 42 can correct the aberrations without deteriorating the aberrations of the on-axis light for at least one of the coma aberration, magnification chromatic aberration, and distortion of the off-axis light even when the eyebox region is enlarged.

[0066] Therefore, as described above, the fourth design condition is that when the distance from the lens surface closest to the eye of the observer OP arranged in the space (for example, the eyebox region) to the end of the lens surface closest to the display unit 30 is d1, and the distance from the lens surface closest to the eye of the observer OP to the display unit 30 is d2, d1 / d2 > 0.5 the optical unit 42 is configured to satisfy the fourth conditional expression shown. Here, it is assumed that the eye relief is 20 mm.

[0067] Therefore, by configuring the optical unit 42 so as to satisfy the fourth conditional expression according to the fourth design condition, even when the size of the eye box region formed by the optical unit 42 is increased, it is possible to correct aberrations of off-axis light, such as coma aberration, chromatic aberration of magnification, and distortion, without deteriorating the aberrations of on-axis light.

[0068] The image display device according to the present embodiment has a focus on the light incident side at a position where a left-eye display image is set as a display image of an object, emits light from the focal plane as parallel light, and forms a left-eye visualizable region where the left-eye display image can be visually recognized, the left-eye optical unit 42L as a left-side optical system; has a focus on the light incident side at a position where a right-eye display image different from the left-eye display image is set, emits light from the focal plane as parallel light, and forms a right-eye visualizable region where the right-eye display image can be visually recognized, the right-eye optical unit 42R as a right-side optical system; a housing case 41 as a housing portion that houses the left-side optical system and the right-side optical system; and is provided with In at least one of the left-side optical system and the right-side optical system, when the distance from the end of the lens surface on the light incident side to the end of the lens surface on the light emission side is d1, and the distance from the position of the display image to the end of the lens surface on the light emission side is d2, d1 / d2>0.5 It is possible to configure it so as to satisfy the conditional expression indicated by.

[0069] Note that if the distance d1 exceeds the distance d2, it becomes difficult to configure the image display device 40 of the present disclosure. Therefore, the upper limit value of the value of (d1 / d2) in the fourth conditional expression is "1". Therefore, 1>d1 / d2>0.5 It is preferable to configure the optical unit 42 so as to satisfy the conditional expression in which the upper limit value is defined in the fourth conditional expression indicated by.

[0070] Here, the end portions of the lens surfaces, which are the starting points of the distances d1 and d2 described above, vary depending on the shape of the lens surfaces. In the present embodiment, the end portions of the lens surfaces are located in a plane perpendicular to the optical axis and in a plane where only the vertex of the lens surface contacts. For example, the end portion of the lens surface on the side closest to the display unit 30 in the optical unit 42 refers to the portion that protrudes the most toward the display unit 30 side in the optical axis direction of the optical unit 42.

[0071] Figures 6 to 8 show the end portions of lens surfaces of various shapes. Figure 6 shows the end portion of the lens surface of the convex lens Lf1, Figure 7 shows the end portion of the lens surface of the concave lens Lf2, and Figure 8 shows the end portion of the lens surface of the aspherical lens Lf3. As shown in Figure 6, in the case of a convex surface, it is the portion that coincides with the position where the optical axis intersects the lens surface. As shown in Figure 7, in the case of a concave surface, it is the edge portion of the lens. As shown in Figure 8, in the case of an aspherical surface, it is the portion that protrudes the most toward the display unit 30 side in the optical axis direction.

[0072] By the way, when the observer OP views the captured image Im with both eyes, such as in stereoscopic viewing, it is preferable to display the left and right images separately corresponding to the interpupillary distance PD of both eyes of the observer OP. For this reason, it is preferable that the lens diameters of the optical units 42R and 42L are each equal to or less than the interpupillary distance PD. For example, when an observer with an interpupillary distance PD of 65 mm is used as a standard, it is preferable that the lens diameters of the optical units 42R and 42L are each 65 mm or less. For this reason, it is preferable that the optical unit 42 is formed using the following fifth design condition and sixth design condition.

[0073] The fifth design condition is When the focal length of the optical unit 42 is f, the distance of the captured image Im displayed by the display unit 30 (for example, the distance indicating the length of the diameter of the inscribed circle, the diameter of the circumscribed circle, the sides, and the diagonal, etc. of the image display area, or the size) is D, and the expected irradiation angle of the light from the optical axis by the optical unit 42 is θ, f ≦ (D / 2) / sinθ is to form the optical unit 42 with a focal length of 100 mm or less so as to satisfy the fifth conditional expression shown.

[0074] The distance D of the captured image Im is preferably set to be a distance equal to or greater than the length of the shortest straight line among the straight lines passing through the center of the captured image Im on the displayed captured image Im. In this case, the distance D of the captured image Im is the length or size of the image display area of the display unit 30, and includes a distance equal to or greater than the length of the straight line passing through the center of the area (or image) in the image display area. For example, when the captured image Im is circular, the diameter is set as the distance D. When the captured image Im is elliptical, the minor axis is set as the distance D. Note that the center of the captured image Im may be the optical axis, the visual axis at which the observer visually observes, or any position within the captured image Im.

[0075] By using the fifth design condition, the optical unit 42 can be formed in consideration of the constraint on the size of the captured image Im displayed on the display unit 30 and the constraint on the expected light irradiation angle from the optical axis by the optical unit 42. For example, assuming that the distance of the captured image Im is defined by the interpupillary distance PD by binocular vision and is 65 mm or less, and when the expected irradiation angle θ is equal to or greater than that of a standard eyepiece lens with a magnification of 10x and a field number of 18, the focal length f is 100 mm or less. Also, the expected irradiation angle θ corresponds to the semi-field angle ω.

[0076] Also, the sixth design condition is when the focal length of the optical unit 42 is f, the size (pixel size) of the pixels constituting the captured image Im displayed on the display unit 30 is S, and the resolution of the eye is R f≧S / tanR to form the optical unit 42 with a focal length of 25 mm or more so as to satisfy the sixth conditional expression represented by

[0077] By using the sixth design condition, the optical unit 42 can be formed in consideration of the constraint on the size of the pixels constituting the captured image Im by the display unit 30 and the constraint on the resolution of the eye. That is, it is possible to suppress the deterioration of the image quality of the captured image Im in which the size of the pixels constituting the captured image Im is perceived due to the resolution of the eye. For example, when the size (pixel size) S of the pixels constituting the captured image Im by the display unit 30 is 15 μm or more and the resolution R of the eye is 2 minutes or less, the focal length f is 25 mm or more.

[0078] From these fifth and sixth design conditions, when forming the captured image Im by the display unit 30 with a pixel size S of 15 μm or more for the observer OP with an eye width PD of 65 mm, the focal length f of the optical unit 42 is preferably 25 mm or more and 100 mm or less. By setting the focal length f of the optical unit 42 to be 25 mm or more and 100 mm or less, the image display device 40 can suppress the granularity of the image due to visual discrimination of individual pixels while maintaining the half angle of view, thereby improving the image quality.

[0079] As described above, when a lens is arranged in a region where the on-axis light JI and the off-axis light JE (see FIG. 5) overlap, it is difficult to correct the aberration peculiar to the off-axis light JE with the arranged lens. For this reason, on the lens surface on the light incident side, it is desirable that the on-axis light JI (for example, the chief ray of the on-axis light) and the off-axis light JE (for example, the chief ray of the off-axis light) do not overlap as much as possible, and the ray interval between the chief ray of the on-axis light JI and the chief ray of the off-axis light JE is more separated. That is, on the lens surface on the light incident side (for example, the lens surface on the display unit 30 side of the lens Lf shown in FIG. 9A), it is preferable to configure the optical unit 42 so as to have a ray interval such that the chief ray of the on-axis light and the chief ray of the off-axis light do not overlap among the light from the surface on which the captured image Im, which is the focal plane, or the captured image Im is arranged.

[0080] In the optical unit 42 in this embodiment, the lens surface where the chief ray is most separated is the lens surface closest to the display unit 30. At this lens surface (for example, the lens surface on the display unit 30 side of the lens Lf in FIG. 9A described later), the chief ray of the on-axis light JI (hereinafter referred to as the chief ray of the central field angle) and the chief ray of the off-axis light JE having the maximum field angle at the outermost part of the region where the captured image Im can be displayed (hereinafter referred to as the chief ray of the maximum field angle) are separated from each other. Then, when the chief ray of the maximum field angle passes through the lens surface closest to the display unit 30 of the optical unit 42, at the effective diameter of the lens through which the chief ray passes, the distance from the optical axis (for example, the optical axis CL) to the effective diameter of the lens is longer than half of the length from the optical axis to the effective diameter of the lens, and the chief ray passes through the lens surface at a position away from the optical axis. For example, at the effective diameter of the lens, the chief ray of the maximum field angle passes through a region outside the concentric circle region having a diameter equal to half of the effective diameter of the lens. This is because, at the lens surface closest to the display unit 30, the respective chief rays of the on-axis light JI and the off-axis light JE are separated, so that a spherical or aspherical surface that gives optimal refraction to each can be defined.

[0081] As a result, it was found that even when the eye box region is enlarged, it is possible to correct the coma aberration, magnification chromatic aberration, and distortion of the off-axis light without deteriorating the aberration of the on-axis light. Note that by configuring the optical unit 42 to satisfy the fourth design condition, even when the eye box region is enlarged, it is possible to correct the coma aberration, magnification chromatic aberration, and distortion of the off-axis light without deteriorating the aberration of the on-axis light. However, at the effective diameter of the lens of the optical system, by making the chief ray of the maximum field angle pass through a region outside the concentric circle region having a diameter equal to half of the effective diameter of the lens, more detailed aberration correction can be achieved.

[0082] Therefore, the seventh design condition is When the chief ray of the maximum angle of view passes through the lens surface closest to the display unit 30 of the optical unit 42, at the effective diameter of the lens, it passes through a region outside the concentric circle region having a diameter equal to half the length of the effective diameter of the lens (for example, a region away from the optical axis). That is, the optical unit 42 is preferably configured to pass through a position having a diameter larger than 1 / 2 of the effective diameter of the lens (for example, the lens Lf shown in FIG. 9A) through which the chief ray of the maximum angle of view of the light of the captured image (display image) Im is incident. That is, the seventh design condition is Let D be the distance of the captured image Im displayed by the display unit 30 (for example, the distance indicating the length of the diameter of the inscribed circle, the diameter of the circumscribed circle, the sides, the diagonal, etc. of the image display area, or the size), φ be the effective diameter of the lens closest to the display unit 30 of the optical unit 42 LF , d3 be the distance between the display unit 30 and the lens closest to the display unit 30 of the optical unit 42, and P be the distance between the display unit 30 and the entrance pupil Inp IN In this case, the condition value Q is 1 / 2 < Q < 1 Q = [D · {1 - (d3 / P IN )}] / φ LF The optical unit 42 is configured to satisfy the seventh conditional expression represented by this.

[0083] FIG. 9A schematically shows the configuration of the optical unit 42. FIG. 9B shows an enlarged view of the periphery of the pupil. In FIG. 9A, since the entrance pupil Inp and the exit pupil Exp are close to each other, the description of the exit pupil Exp is omitted. In FIG. 9B, the positional relationship between the entrance pupil Inp and the exit pupil Exp is exaggeratedly shown. The entrance pupil Inp is the position where the chief rays of each angle of view due to the light from the captured image Im intersect when the chief rays travel straight. For example, as shown in FIG. 9B, the position where the ray (the ray shown by the dotted line in FIG. 9B) assuming that the chief ray of the maximum angle of view incident on the optical unit 42 travels straight intersects with the ray (the ray shown by the dashed-dotted line in FIG. 9B) assuming that the chief ray of the central angle of view travels straight is the position of the entrance pupil Inp. On the other hand, the position of the exit pupil Exp is the position where the chief rays of each angle of view reaching the image plane intersect when the chief rays travel backward, that is, the position where the refracted chief rays (the rays shown by the double-dotted lines in FIG. 9B) intersect.

[0084] As shown in FIG. 9A, the principal ray of the maximum picture angle is incident on the optical unit 42 at an inclination represented by (D / 2) / P IN . At this time, the height h from the optical axis on the lens surface of the lens Lf closest to the display unit 30 of the optical unit 42 is represented by the following formula. h = (D / 2) - { (D / 2) / P } · d3 IN = (D / 2) · { 1 - (d3 / P )} IN Therefore, the conditional value Q can be expressed by the following formula, and the optical unit 42 can be determined from the relationship between the effective diameter φ of the lens closest to the display unit 30 of the optical unit 42 LF and the height h indicating the position where the principal ray of the maximum picture angle passes through the lens. Q = h · (2 / φ LF )

[0085] In the example shown in FIG. 9A, among the optical unit 42, the lens surface on the display unit 30 side of the lens Lf is an example of a first refracting surface with a convex surface facing the light incident side of the first surface on which the light of the captured image Im of the present disclosure is incident. Also, among the optical unit 42, the lens surface on the observer OP side of the lens Le is an example of a second refracting surface with a convex surface facing the light emitting side of the second surface from which the light of the present disclosure is emitted. And the lens surface on the display unit 30 side of the lens Lf is an example of the first surface on which light is incident on the optical unit 42, and the lens surface on the observer OP side of the lens Le is an example of the last surface from which light is emitted from the optical unit 42. Further, the lens Lf is an example of the first lens of the present disclosure, the lens Le is an example of the second lens of the present disclosure, and the optical unit 42 including the lens Lf and the lens Le is an example of the lens group of the present disclosure.

[0086] Next, the above design conditions are verified using a specific lens example of the optical unit 42.

[0087] First, while forming a large eye box region IB, it is considered difficult for the optical unit 42 capable of correcting off-axis aberration to be a single lens. An optical unit 42 using a single lens that was difficult to correct off-axis aberration will be described.

[0088] <Lens Example 1> FIG. 10 shows, as an example of a lens, an example of the configuration of an optical unit 42 using a single lens of one group and one element and an example of an optical path. Hereinafter, since the optical unit 42R and the optical unit 42L have the same configuration, individual descriptions thereof will be omitted. As shown in FIG. 10, the optical unit 42 is formed of a single lens having optical surfaces with surface numbers P1 and P2 in order from the captured image Im. The optical surface becomes a refractive surface when the refractive index of the medium on one side and the refractive index of the medium on the other side with the optical surface as a boundary are different. In the example shown in FIG. 10, a case is shown where the optical unit 42 is arranged so as to be separated by 69.7 mm by a distance d0 from the captured image Im to the end of the lens surface closest to the display unit 30.

[0089] The following Table 1 shows the specifications of the optical unit 42 of the lens example 1. In Table 1, the surface number m corresponds to the surface number of the optical surface shown in FIG. 10. The radius of curvature r indicates the radius of curvature of each optical surface, the surface interval d indicates the distance on the optical axis from each optical surface to the next optical surface, the refractive index nd indicates the refractive index with respect to the d-line, and the dispersion νd indicates the Abbe number. In the specifications shown in Table 1, "mm" is adopted as the unit of the radius of curvature r and the surface interval d. However, since the optical unit 42 can obtain the same optical performance even when proportionally enlarged or reduced, the unit is not limited to "mm", and other units can also be used.

[0090]

Table 1

[0091] Note that Table 1 shows an example of a spherical optical surface with the optical axis CL as the axis, but the optical surface is not limited to a spherical shape and may be an aspherical shape. The same applies to other lens examples described below. Also, the effective diameter of the lens in Lens Example 1 is 24.83, assuming the distance of the captured image Im (the distance or size of the image display area) is 31.66.

[0092] The optical unit 42 functions as an objective lens, which is an afocal optical system that emits light from the captured image Im as parallel light. That is, the optical unit 42 has a focal length f, and is set such that the captured image Im of the object by the display unit 30 is located at the focal point on the light incident side, and the display unit 30 is attached to the optical unit 42. In this way, the optical unit (the optical system having the above lens) 42 has a focal point on the light incident side at the position where the captured image (display image) Im of the object is set, and emits light from that focal plane (in this case, the captured image Im or the plane on which the captured image Im is arranged) as parallel light.

[0093] As shown in FIG. 10, the optical unit 42 is set as an afocal optical system such that the captured image Im (display image) of the object by the display unit 30 is located at the focal position of the focal length f on the display unit 30 side, and the light emitted from the optical unit 42 toward the observer OP is parallel light. The parallel light emitted from this optical unit 42 reaches the eye of the observer OP, forms an image on the retina of the observer OP, and the captured image Im is perceived by the observer OP.

[0094] For the optical unit 42 of Lens Example 1 shown in FIG. 10, the value (= d1 / d2) according to the fourth conditional expression is 0.19, and the value (= Q) according to the seventh conditional expression is 0.323. The optical unit 42 of Lens Example 1 does not satisfy the fourth design condition. Although the eye box area formed by the optical unit 42 can be enlarged, it is difficult to correct aberrations due to off-axis coma, longitudinal chromatic aberration, and distortion. That is, by correcting the off-axis light aberration, the aberration of the on-axis light deteriorated.

[0095] In addition, the optical unit 42 of lens example 1 does not satisfy the seventh design condition, and at the lens surface closest to the display unit 30 in the optical unit 42, the separation between the chief ray of the center field angle and the chief ray of the maximum field angle is insufficient. For this reason, it was difficult to define a spherical or aspherical surface that provides appropriate refraction for each of the center field angle and the maximum field angle. Therefore, by configuring the optical unit 42 with a single lens, it is possible to increase the size of the eye box region, but since aberrations that are difficult to correct remain, it is considered that image quality deterioration of the image viewed by the observer OP occurs.

[0096] <Lens Example 2> Next, an optical unit 42 that attempts to correct aberrations while forming a large eye box region IB with a single lens will be described. FIG. 11 shows an example of the configuration of an optical unit 42 composed of a single lens with specifications different from those of lens example 1 and an example of an optical path. The optical unit 42 shown in FIG. 11 shows the case where the distance d0 from the captured image Im to the end of the lens surface closest to the display unit 30 is arranged at a separation of 73.76 mm.

[0097] The following Table 2 shows the specifications of the optical unit 42 of lens example 2. In Table 2, the surface number m corresponds to the surface number of the optical surface shown in FIG. 3. Also, the radius of curvature r indicates the radius of curvature of each optical surface, the surface interval d indicates the distance on the optical axis from each optical surface to the next optical surface, the refractive index nd indicates the refractive index with respect to the d line, and the dispersion νd indicates the Abbe number. In the specifications shown in Table 2, "mm" is adopted as the unit of the radius of curvature r and the surface interval d. However, since the optical unit 42 can obtain the same optical performance even if it is proportionally enlarged or reduced, the unit is not limited to "mm", and other units can also be used. Also, the effective diameter of the lens in lens example 2 is 29.02, and it is assumed that the distance (distance or size of the image display area) of the captured image Im is 30.99.

[0098]

Table 2

[0099] For the optical unit 42 of lens example 2, the value (= d1 / d2) according to the fourth conditional expression is 0.455, and the value (= Q) according to the seventh conditional expression is 0.553. The optical unit 42 of lens example 2 satisfies the seventh design condition. Therefore, on the lens surface closest to the display unit 30, it is possible to define a spherical or aspherical surface that provides appropriate refraction for each of the central field angle and the maximum field angle. However, the optical unit 42 of lens example 2 does not satisfy the fourth design condition. Therefore, although the size of the eye box region formed by the optical unit 42 can be increased, it is difficult to correct aberrations due to coma aberration, longitudinal chromatic aberration, and distortion of off-axis light, and by correcting the aberrations of off-axis light, the aberrations of on-axis light deteriorate.

[0100] As described above, when the optical unit 42 is configured by a single lens, although the size of the eye box region formed by the optical unit 42 can be increased, it may be difficult to correct aberrations due to coma aberration, longitudinal chromatic aberration, and distortion of off-axis light. However, by satisfying the seventh design condition, aberration correction that can be expected to improve image quality is considered possible. That is, in lens example 2, although the size of the eye box region can be increased and a situation where correction of various aberrations is difficult occurs, since it is possible to define a spherical or aspherical surface that provides appropriate refraction for each of the central field angle and the maximum field angle, improvement in the image quality of the image viewed by the observer OP can be expected as compared with a lens that does not satisfy the seventh design condition.

[0101] <Lens Example 3> FIG. 12 shows, as lens example 3, an example of the configuration of an optical unit 42 composed of a two-lens group and an example of an optical path. The optical unit 42 shown in FIG. 12 is formed by a two-lens group having optical surfaces with surface numbers P1, P2, and P3 in order from the captured image Im. In the example shown in FIG. 12, the case where the optical unit 42 is arranged at a distance d0 of 69.7 mm from the captured image Im is shown.

[0102] Table 3 below shows the specifications of the optical unit 42 according to Lens Example 3. Note that the effective diameter of the lens in Lens Example 3 is 31.20, and it is assumed that the distance of the captured image Im (the distance or size of the image display area) is 31.19.

[0103]

Table 3

[0104] For the optical unit 42 according to Lens Example 3, the value (= d1 / d2) according to the fourth conditional expression is 0.53, and the value (= Q) according to the seventh conditional expression is 0.643. The optical unit 42 of Lens Example 3 satisfies the fourth design condition, and it is possible to enlarge the eye box area formed by the optical unit 42, and it is possible to correct aberrations due to coma aberration, longitudinal chromatic aberration, and distortion of off-axis light.

[0105] Also, the optical unit 42 according to Lens Example 3 satisfies the seventh design condition, and on the lens surface closest to the display unit 30 in the optical unit 42, the chief rays of the center field angle and the maximum field angle can be separated respectively. Therefore, it was possible to define a spherical or aspherical surface that gives appropriate refraction for each of the center field angle and the maximum field angle. Therefore, in Lens Example 3, since it is possible to enlarge the eye box area and correct various aberrations, an improvement in the image quality of the image viewed by the observer OP can be expected.

[0106] Note that when the optical unit 42 is formed with a lens configuration of one group of two lenses, since the second surface is filled with a glass material, it is not preferable in terms of cost and weight, and a configuration of two or more groups is preferable.

[0107] <Lens Example 4> FIG. 13 shows an example of the configuration of the optical unit 42 and an example of the optical path by a two-group three-lens as Lens Example 4. The optical unit 42 shown in Fig. 13 is formed of two groups of three lenses having optical surfaces with surface numbers P1, P2, P3, P4, and P5 in order from the captured image Im. In the example shown in Fig. 13, the case where the optical unit 42 is arranged at a distance d0 of 62.8 mm from the captured image Im is shown.

[0108] The following Table 4 shows the specifications of the optical unit 42 according to lens example 4. Note that the effective diameter of the lens in lens example 4 is 33.45, and it is assumed that the distance of the captured image Im (the distance or size of the image display area) is 31.26.

[0109]

Table 4

[0110] For the optical unit 42 according to lens example 4, the value (= d1 / d2) according to the fourth conditional expression is 0.60, and the value (= Q) according to the seventh conditional expression is 0.737. The optical unit 42 of lens example 4 satisfies the fourth design condition, and it is possible to increase the size of the eye box region formed by the optical unit 42, and it is possible to correct aberrations due to coma aberration, chromatic aberration of magnification, and distortion of off-axis light. Further, the optical unit 42 according to lens example 4 also satisfies the seventh design condition, and at the lens surface closest to the display unit 30 in the optical unit 42, the chief rays of the central field angle and the maximum field angle can be separated respectively. Therefore, it was possible to define a spherical or aspherical surface that gives appropriate refraction for each of the central field angle and the maximum field angle. Therefore, in lens example 4, since it is possible to increase the size of the eye box region and correct various aberrations, it is possible to expect an improvement in the image quality of the image viewed by the observer OP.

[0111] <Lens Example 5> Fig. 14 shows an example of the configuration of the optical unit 42 and an example of the optical path by three groups of three lenses as lens example 5. The optical unit 42 shown in Fig. 14 is formed by three groups of three lenses having optical surfaces with surface numbers P1, P2, P3, P4, P5, and P6 in order from the captured image Im. In the example shown in Fig. 14, the case where the optical unit 42 is arranged at a distance of 43.8 mm as the distance d0 from the captured image Im is shown.

[0112] The following Table 5 shows the specifications of the optical unit 42 according to lens example 5. It is assumed that the effective diameter of the lens in lens example 5 is 32.16 and the distance of the captured image Im (the distance or size of the image display area) is 31.59.

[0113]

Table 5

[0114] The optical unit 42 according to lens example 5 has a value (= d1 / d2) according to the fourth conditional expression of 0.69 and satisfies the fourth design condition. Also, the value (= Q) according to the seventh conditional expression is 0.816, and the seventh design condition is also satisfied. Therefore, the optical unit 42 of lens example 5 can enlarge the eye box area and can correct aberrations due to coma aberration, magnification chromatic aberration, and distortion of off-axis light. Also, on the lens surface closest to the display unit 30, the chief rays of the center field angle and the maximum field angle can be separated, and it is possible to define a spherical or aspherical surface that gives appropriate refraction independently for each of the center field angle and the maximum field angle. Therefore, in lens example 5, since the eye box area can be enlarged and various aberrations can be corrected, an improvement in the image quality of the image viewed by the observer OP can be expected.

[0115] <Lens Example 6> Fig. 15 shows an example of the configuration of the optical unit 42 and an example of the optical path by a three-group four-lens as lens example 6. The optical unit 42 shown in Fig. 15 is formed by four lenses in three groups having optical surfaces with surface numbers P1, P2, P3, P4, P5, P6, and P7 in order from the captured image Im. In the example shown in Fig. 15, the case where the optical unit 42 is arranged at a distance of 19.5 mm as the distance d0 from the captured image Im is shown.

[0116] The following Table 6 shows the specifications of the optical unit 42 according to lens example 6. It is assumed that the effective diameter of the lens in lens example 6 is 28.38 and the distance of the captured image Im (distance or size of the image display area) is 31.80.

[0117]

Table 6

[0118] The optical unit 42 according to lens example 6 has a value (= d1 / d2) according to the fourth conditional expression of 0.85 and satisfies the fourth design condition. Also, the value (= Q) according to the seventh conditional expression is 0.80, and the seventh design condition is also satisfied. Therefore, the optical unit 42 of lens example 6 can enlarge the eye box area and can correct aberrations due to coma aberration, magnification chromatic aberration, and distortion of off-axis light. Also, on the lens surface closest to the display unit 30, the chief rays of the center field angle and the maximum field angle can be separated, and it is possible to define a spherical or aspherical surface that gives appropriate refraction independently for each of the center field angle and the maximum field angle. Therefore, in lens example 6, it is possible to enlarge the eye box area and correct various aberrations, so an improvement in the image quality of the image viewed by the observer OP can be expected.

[0119] <Lens Example 7> Fig. 16 shows, as lens example 7, an example of the configuration of an optical unit 42 formed by three lenses in two groups with different specifications from lens example 4 and an example of the optical path. The optical unit 42 shown in Fig. 16 is formed by two groups of three lenses having optical surfaces with surface numbers P1, P2, P3, P4, and P5 in order from the captured image Im. In the example shown in Fig. 16, the case where the optical unit 42 is arranged at a distance of 10.0 mm as the distance d0 from the captured image Im is shown.

[0120] The following Table 7 shows the specifications of the optical unit 42 according to Lens Example 7. It is assumed that the effective diameter of the lens in Lens Example 7 is 29.46 and the distance of the captured image Im (the distance or size of the image display area) is 30.47.

[0121]

Table 7

[0122] For the optical unit 42 according to Lens Example 7, the value (= d1 / d2) according to the fourth conditional expression is 0.97, satisfying the fourth design condition. Also, the value (= Q) according to the seventh conditional expression is 0.911, satisfying the seventh design condition. Therefore, the optical unit 42 of Lens Example 7 can enlarge the eye box area and can correct aberrations due to coma aberration, longitudinal chromatic aberration, and distortion of off-axis light. Also, on the lens surface closest to the display unit 30, the chief rays of the center field angle and the maximum field angle can be separated, and it is possible to define a spherical or aspherical surface that gives appropriate refraction independently for each of the center field angle and the maximum field angle. Therefore, in Lens Example 7, since it is possible to enlarge the eye box area and correct various aberrations, an improvement in the image quality of the image viewed by the observer OP can be expected.

[0123] <Lens Example 8> Fig. 17 shows, as Lens Example 8, an example of the configuration of an optical unit 42 formed by three groups of three lenses with different specifications from those of Lens Example 5 and an example of the optical path. The optical unit 42 shown in Fig. 17 is formed of three groups of three lenses having optical surfaces with surface numbers P1, P2, P3, P4, P5, and P6 in order from the captured image Im. In the example shown in Fig. 17, the case where the optical unit 42 is arranged at a distance d0 of 8.3 mm from the captured image Im is shown.

[0124] The following Table 8 shows the specifications of the optical unit 42 according to lens example 8. It is assumed that the effective diameter of the lens in lens example 8 is 29.27 and the distance of the captured image Im (distance or size of the image display area) is 29.41.

[0125]

Table 8

[0126] For the optical unit 42 according to lens example 8, the value (= d1 / d2) according to the fourth conditional expression is 0.99, satisfying the fourth design condition. Also, the value (= Q) according to the seventh conditional expression is 0.919, satisfying the seventh design condition. Therefore, the optical unit 42 of lens example 8 can enlarge the eye box area and can correct aberrations due to coma aberration, magnification chromatic aberration, and distortion of off-axis light. Also, at the lens surface closest to the display unit 30, the chief rays of the center field angle and the maximum field angle can be separated, and it is possible to define a spherical or aspherical surface that gives appropriate refraction independently for each of the center field angle and the maximum field angle. Therefore, in lens example 8, since it is possible to enlarge the eye box area and correct various aberrations, an improvement in the image quality of the image viewed by the observer OP can be expected.

[0127] <Lens Example 9> Fig. 18 shows, as lens example 9, an example of the configuration of an optical unit 42 and an example of the optical path formed of three groups of three lenses having different specifications from lens example 5 and lens example 8. The optical unit 42 shown in FIG. 18 is formed by three lenses in three groups having optical surfaces with surface numbers P1, P2, P3, P4, P5, and P6 in order from the captured image Im. In the example shown in FIG. 18, the case where the optical unit 42 is arranged at a distance d0 of 63.8 mm from the captured image Im is shown.

[0128] The following Table 9 shows the specifications of the optical unit 42 according to lens example 9. It is assumed that the effective diameter of the lens in lens example 9 is 27.38 and the distance of the captured image Im (distance or size of the image display area) is 31.94.

[0129]

Table 9

[0130] For the optical unit 42 of lens example 9, the value (= d1 / d2) according to the fourth conditional expression is 0.48, and the value (= Q) according to the seventh conditional expression is 0.572. The optical unit 42 of lens example 9 satisfies the seventh design condition. Therefore, it is possible to define a spherical or aspherical surface that gives appropriate refraction for each of the central field angle and the maximum field angle on the lens surface closest to the display unit 30. However, the optical unit 42 of lens example 9 does not satisfy the fourth design condition. Therefore, although the size of the eye box area formed by the optical unit 42 can be increased, it is difficult to correct aberrations due to coma aberration, magnification chromatic aberration, and distortion of off-axis light, and by correcting the aberrations of off-axis light, the aberrations of on-axis light deteriorate. Therefore, in lens example 9, although it is possible to increase the size of the eye box area and a situation where correction of various aberrations is difficult occurs, since it is possible to define a spherical or aspherical surface that gives appropriate refraction for each of the central field angle and the maximum field angle, an improvement in the image quality of the image viewed by the observer OP can be expected compared to lenses that do not satisfy the seventh design condition.

[0131] As described above, by configuring the optical unit 42 to satisfy the above design conditions, the optical unit 42 can increase the size of the eyebox area and correct aberrations due to coma aberration, chromatic aberration of magnification, and distortion of off-axis light. Also, on the lens surface closest to the display unit 30, it is possible to separate the chief ray of the center field angle and the chief ray of the maximum field angle, and define a spherical or aspherical surface that gives appropriate refraction independently for each of the center field angle and the maximum field angle.

[0132] In the present embodiment, the optical unit 42 is configured such that the exit pupil Exp is located on the light emission side. As a result, a wide eyebox area IB is formed on the light emission side of the optical unit 42, that is, on the viewing side of the observer OP, and the degree of freedom in setting the head position of the observer OP can be improved.

[0133] FIG. 19 shows an example of the exit pupil Exp in the image display device 40 according to the present embodiment. As shown in FIG. 19, in the image display device 40, the exit pupil Exp is formed by an exit pupil ExpR for the right eye and an exit pupil ExpL for the left eye.

[0134] Also, in the present embodiment, it is formed such that the exit pupil Exp is located on the light emission side of the optical unit 42. As a result, it becomes possible to form the exit pupil of the optical unit 42 to a size corresponding to the lens diameter of the optical unit 42, and the maximum value of the diameters of the exit pupil ExpR for the right eye and the exit pupil ExpL for the left eye can be expanded to a size corresponding to the lens diameter of the optical unit 42. If each eye of the observer OP is positioned within each of these exit pupils of the exit pupil ExpR for the right eye and the exit pupil ExpL for the left eye, the observer OP can visually recognize each of the captured images ImR for the right eye and ImL for the left eye of the observer OP. Therefore, in the ophthalmic system 10 of the present embodiment, a mechanism for adjusting the interpupillary distance PD equipped in a conventional binocular microscope is unnecessary.

[0135] Incidentally, the sizes, i.e., the diameters, of the exit pupil ExpR for the right eye and the exit pupil ExpL for the left eye are limited by the lens diameter of the optical unit 42. On the other hand, there may be a case where it is required to increase the size of the exit pupil Exp to expand the visible range for the observer OP. In this case, the lens diameter of the optical unit 42 may be made larger than the eye width PD so that a part of the optical unit 42 overlaps.

[0136] That is, when the image display device 40 is configured to include the optical units 42R for the right eye and the optical unit 42L for the left eye, the diameter of each of the optical units 42R for the right eye and the optical unit 42L for the left eye is preferably formed to be a diameter equal to or less than the distance corresponding to the eye width PD of the observer OP who observes the captured image (display image) Im. When the image display device 40 is configured such that at least one of the optical units 42R for the right eye and the optical unit 42L for the left eye has a diameter exceeding the distance corresponding to the eye width PD of the observer OP, an overlapping portion where the optical units 42R for the right eye and the optical unit 42L for the left eye overlap is generated. In this case, at least a part of one of the optical units 42R for the right eye and the optical unit 42L for the left eye may be deleted (for example, a so-called D-cut) from the overlapping portion so that the optical units 42R for the right eye and the optical unit 42L for the left eye do not overlap.

[0137] FIG. 20 shows an example of the configuration of the optical unit 42 having a lens diameter larger than the eye width PD. When the lens diameter of the optical unit 42 is made larger than the interpupillary distance PD, the right-eye optical unit 42R and the left-eye optical unit 42L interfere with each other. Therefore, at least one of the right-eye optical unit 42R and the left-eye optical unit 42L may be formed by cutting off the interfering portion. In the example shown in FIG. 20, a case is shown in which a part of the optical unit 42 is equally cut out from the right-eye optical unit 42R and the left-eye optical unit 42L. By doing so, the interval between the optical axis of the right-eye optical unit 42R and the optical axis of the left-eye optical unit 42L is maintained at the preset interpupillary distance PD, and a larger exit pupil Exp can be formed compared to the case where the optical unit 42 is formed with a diameter corresponding to the interpupillary distance PD.

[0138] By the way, by forming a wide eye box region IB outside the exit side of the optical unit 42, the degree of freedom in setting the head position of the observer OP is improved, but there is a risk that stray light enters the eyes of the observer OP. To eliminate this, a suppression member for suppressing the stray light may be provided in the optical path leading to the eyes of the observer OP as the stray light to suppress the entry of the stray light.

[0139] FIG. 21 shows an example of a suppression member for suppressing the stray light entering the eyes of the observer OP. As shown in FIG. 21, the image display device 40 according to the present embodiment includes a housing case 41 that houses the right-eye optical unit 42R and the left-eye optical unit 42L. The housing case 41 covers at least the right-eye optical unit 42R and the left-eye optical unit 42L and has a function of blocking the stray light to the right-eye optical unit 42R and the left-eye optical unit 42L. Further, the housing case 41 has an opening 41H on the light exit side of each of the right-eye optical unit 42R and the left-eye optical unit 42L. The opening 41H is formed so as not to block the optical path leading to the exit pupil Exp.

[0140] In the housing case 41, a light shielding plate 43A is attached as a suppression member to the light emission side of the opening 41H, that is, the observer OP side. The light shielding plate 43A only needs to have a function of suppressing stray light, and an optical member such as a plate that shields stray light or an optical member that attenuates light transmission such as an ND filter can be used. In the example shown in FIG. 21, an example in which the light shielding plate 43A is attached in three directions, upward and left and right, is shown. However, it may be provided at a site that suppresses light in at least one direction that is the main stray light, or may be provided so as to cover the top, bottom, left, and right. The light shielding plate 43A is an example of the light suppression unit of the present disclosure.

[0141] FIG. 22 shows another example of a suppression member that suppresses stray light entering the eyes of the observer OP. In the example shown in FIG. 22, a right-eye suppression member 43BR and a left-eye suppression member 43BL are attached to the housing case 41. Each of the suppression members 43BR and 43BL is formed of an elastic member such as rubber that suppresses discomfort when contacting the head of the observer OP. Thereby, the observer OP can suppress stray light by bringing the head into contact with each of the suppression members 43BR and 43BL. In the example shown in FIG. 22, an example in which an opening 41Ha having a diameter smaller than the opening 41H shown in FIG. 21 is provided in each of the suppression members 43BR and 43BL is shown. The size of the opening 41Ha is set to a predetermined shape assuming an eye relief when the observer OP contacts the suppression members 43BR and 43BL with the head. Of course, the size of the opening 41Ha is not limited to the size shown in FIG. 22. The suppression members 43BR and 43BL are examples of the light suppression unit of the present disclosure.

[0142] ·Modification In the present embodiment, a system (ophthalmic system) applied to an ophthalmic device has been described as an example of the image display device according to the present disclosure. However, the image display device according to the present disclosure is also applicable to other ophthalmic devices that enable stereoscopic vision. For example, the present disclosure is also applicable to other ophthalmic devices that enlarge the eyebox region IB to present an aerial image, that is, provide a relayed exit pupil. An image display device with an enlarged eyebox region IB will be described as a modification.

[0143] FIG. 23 shows an example of the configuration of a modified image display device 40A in which the inbox area IB is enlarged. As shown in FIG. 23, in the modified example, a relay unit 44 for relaying the pupil is attached to the above-described image display device 40. The image display device 40A of the modified example photographs the subject eye and the periphery of the subject eye of the observer with the photographing unit 20, presents the photographed image with the above-described image display device 40, and provides it to the observer OP by the relay unit 44.

[0144] The relay unit 44 includes a housing 46 and an optical member 48. The above-described image display device 40 including the optical unit 42 is attached to the housing 46, and the light emitted from the optical unit 42 is incident inside the housing 46. Further, an optical member 48 is attached inside the housing 46 on the light emission side of the optical unit 42 so as to reflect light in a direction intersecting the emission optical axis of the optical unit 42 (the direction toward the observer OP). The relay unit 44 reflects the light emitted from the optical unit 42 in a direction intersecting the emission optical axis of the optical unit 42, and forms a position conjugate to the emission pupil Exp of the optical unit 42 on the reflection side. That is, the relay unit 44 relays the emission pupil by reforming the emission pupil Exp of the optical unit 42 on the reflection side, which is the direction toward the observer OP.

[0145] The housing 46 of the relay unit 44 to which the above-described image display device 40 is attached is attached to a pedestal (not shown), is formed independently of the photographing unit 20, and is formed non-contact with respect to the observer OP. By forming the image display device 40A of the modified example non-contact with respect to the observer OP, the discomfort of the observer OP caused by the contact of the observer OP with the image display device 40A of the modified example is suppressed.

[0146] As an example of the optical member 48 shown in the modified example, an optical imaging element that forms an image of the same magnification by multiple reflections by a plurality of reflecting surfaces can be used. For example, the optical imaging element includes a plurality of reflecting members in which a plurality of reflecting surfaces are stacked, and the light incident from one stacked end face is reflected by the reflecting surface and emitted from the other stacked end face. Then, the plurality of reflecting members are arranged such that the reflecting surface of one reflecting member and the reflecting surface of the other reflecting member intersect, and the light emitted from the stacked end face of one reflecting member is incident on the stacked end face of the other reflecting member.

[0147] That is, the incident light incident on the optical imaging element, which is an example of the optical member 48, is reflected by the first reflecting surface, and the reflected light is reflected by the second reflecting surface and emitted from the optical imaging element. On the other hand, in the optical imaging element, the first reflecting surface and the second reflecting surface are arranged in a direction in which their reflecting surfaces intersect (are orthogonal) to each other. In this way, when the first reflecting surface and the second reflecting surface are arranged orthogonally in a plan view, the incident light to the optical imaging element and the light emitted from the optical imaging element are parallel in a plan view of the optical imaging element. For this reason, each of the plurality of light points, which is an object point on the incident side of the optical imaging element, is focused on the emission side of the optical imaging element and imaged as an image point. Therefore, the relay unit 44 reforms the exit pupil Exp at a position conjugate to the exit pupil Exp of the optical unit 42.

[0148] Note that the optical imaging element, which is an example of the optical member 48, can be treated as a recursive element, and more specifically, a recursive transmission element. Recursive reflection reflects light in the direction opposite to the direction of the light incident on the element by a plurality of orthogonal reflecting surfaces. On the other hand, the optical imaging element has the property of transmitting the incident light to the surface opposite to the incident surface and emitting it while changing the direction, and the light beam is folded back symmetrically with respect to the plane orthogonal to the normal of the optical imaging element. This corresponds to the fact that when the optical imaging element folds the space, the traveling direction of the light beam is not changed in the vertical direction of the optical imaging element and acts recursively, so it can be considered a recursive transmission element.

[0149] Other examples of the optical pixel device include an optical control panel in which a plurality of intersecting reflecting surfaces are used as a unit optical system, and the unit optical systems are arranged in a plurality in a plane direction intersecting the plurality of reflecting surfaces. The control panel is formed by arranging a plurality of unit optical systems each having a configuration in which two mirror surfaces substantially perpendicular to a predetermined plane are substantially orthogonal to each other, for example, a plurality of two-sided corner reflectors.

[0150] In addition, in the present embodiment, the system applied to the ophthalmic device has been described as an example of the image display device according to the present disclosure. However, the image display device according to the present disclosure is not limited to the ophthalmic system applied to the ophthalmic device. That is, the present disclosure is applicable to any device that displays an image, and the image display system according to the present disclosure is applicable to any system equipped with a device that displays an image. Next, application examples of the image display device to which the present disclosure is applicable and the image display system equipped with the image display device will be illustrated.

[0151] · Application examples Application examples include the application of the image display device according to the present disclosure to a display device of an observation system that observes a distant object by an optical device such as binoculars and a periscope. By applying the image display device according to the present disclosure to the observation system for observing the distant object, the observer OP can observe the distant object in a non-contact state with the image display device 40, and the discomfort of the observer OP caused by contact is suppressed. In addition, since the apparent size of the image viewed through the optical unit 42 does not change, the head of the observer OP can move within the eye box area. Therefore, there is a greater tolerance for the posture of the observer OP compared to the posture in which the head of the observer OP contacts the optical device such as binoculars and a periscope. In addition, in the present embodiment, the system applied to the ophthalmic device has been described as an example of the image display device according to the present disclosure. However, the image display device according to the present disclosure is also applicable when each of a plurality of observers can visually observe an object. For example, the system may include a plurality of image display devices according to the present disclosure, and the same image may be displayed on each of the plurality of image display devices, or an image-processed image may be displayed on some of the image display devices.

[0152] Although embodiments of the present disclosure have been described, the technical scope of the present disclosure is not limited to the scope described in the above embodiments. Various changes or improvements can be made to the above embodiments without departing from the gist of the present disclosure, and the forms with such changes or improvements are also included in the technical scope of the present disclosure. In addition, all documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference.

Explanation of Reference Numerals

[0153] 10 Ophthalmic system 20 Imaging unit 22 Microscope 24 Camera 26 Camera controller 30 Display unit 40 Image display device 42 Optical unit IB I-box area Im Captured image OB Object OP Observer

Claims

[Claim 1] an optical system having a focal point on a light incident side at a position where a display image of an object is set, and emitting light from the focal plane as parallel light; a housing portion that houses the optical system, a visible region in which the display image can be viewed is derived based on an effective diameter of a lens included in the optical system and an angle between a chief ray of a maximum angle of view and an optical axis of the optical system; If the angle between the chief ray of the maximum angle of view in the optical system and the optical axis of the optical system is ω, 15 degrees≦ω≦50 degrees The visible area is formed so as to satisfy the conditional expression represented by When the visible area in which the display image can be viewed is IB, 185000≧IB≧7570mm ３ The conditional expression shown in the optical system includes a first lens and a second lens, When a distance from an end of a lens surface on a light incident side of the first lens to an end of a lens surface on a light exit side of the second lens is defined as d1, and a distance from a position of the display image to an end of a lens surface on the light exit side of the second lens is defined as d2, 1>d1 / d2>0.5 and corrects at least one off-axis aberration of off-axis light, including coma aberration, lateral chromatic aberration, and distortion. Optical unit.

Images