ophthalmic devices

Abstract

The present invention provides an ophthalmic device that can expand the detection range of the eye under examination in the direction along the principal optical axis of the optical head with a simple configuration. [Solution] The ophthalmic apparatus 1 comprises an optical head 5, parallel light projection units 30R and 30L, a displacement mechanism 50 for displacing the position and orientation of the parallel light projection units 30R and 30L, and an observation system 12 for capturing a bright spot image 30 of the reflected light 30 of the parallel light projected onto the eye E under examination by the image sensor 12g when the reflected light passes through the objective lens 12a to the image sensor 12g. When a predetermined range is defined as a position at a distance of the working distance of the objective lens 12a from the eye E under examination in the direction along the principal optical axis of the optical head, the displacement mechanism 50 can displace the parallel light projection units 30R and 30L to a position and orientation that enables the image sensor 12g to capture a bright spot image when the optical head 5 is located outside the predetermined range.

Description

Technical Field

[0001] The present invention relates to an ophthalmic device including an optical head.

Background Art

[0002] In ophthalmology, various eye characteristics such as the refractive power of the eye to be examined, the corneal shape, the intraocular pressure, and the number of corneal endothelial cells are acquired (measured, photographed, observed, etc.) using an ophthalmic device. Before acquiring the eye characteristics of the eye to be examined by this ophthalmic device, alignment of the optical head of the ophthalmic device with respect to the eye to be examined is performed. This alignment of the optical head includes Z alignment, which is alignment in the direction along the principal optical axis of the optical head (operating distance direction), and XY alignment, which is alignment in two directions perpendicular to this direction. When performing Z alignment, the Z-direction distance between the eye to be examined and the optical head is measured, and based on this measurement result, position adjustment of the optical head in the Z direction is performed.

[0003] For example, the ophthalmic device described in Patent Document 1 is an auto-refractometer, and a pair of parallel light projection units that emit parallel light and a keratometry light source that emits keratometry light are provided on the front surface of its optical head. This ophthalmic device projects the parallel light emitted from the pair of parallel light projection units and the keratometry light emitted from the keratometry light source onto the anterior eye segment of the eye to be examined from an oblique direction, and photographs the anterior eye segment image of this anterior eye segment through an objective lens having a principal optical axis. Then, the ophthalmic device measures the Z-direction distance between the eye to be examined and the optical head based on the ratio between the interval of the bright spots corresponding to the pair of parallel lights in the anterior eye segment image and the interval of the keratometry image in the anterior eye segment image, and performs Z alignment of the optical head based on this measurement result.

[0004] In addition, the ophthalmic device (auto-refractometer) described in Patent Document 2 separately provides a light lever type Z alignment system on the optical head to measure the Z-direction distance between the eye to be examined and the optical head, and performs Z alignment of the optical head based on this measurement result.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-127648 [Patent Document 2] Japanese Patent Publication No. 2024-60915 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the ophthalmic apparatus described in Patent Document 1, the irradiation range of parallel light from a pair of parallel light projection units to the eye under examination depends on the lens diameter of the parallel light projection units. Therefore, the Z-direction position range of the optical head capable of measuring distance in the Z-direction, in other words, the detection range of the eye under examination in the Z-direction of the optical head, is limited. For this reason, depending on the Z-direction positional relationship between the eye under examination and the optical head at the start of alignment, Z-alignment may not be possible.

[0007] In the ophthalmic device described in Patent Document 2, a separate optical lever-type Z-alignment system must be provided on the optical head in order to perform Z-alignment, which leads to problems of increased cost and larger device size.

[0008] This invention has been made in view of these circumstances, and aims to provide an ophthalmic device that can expand the detection range of the eye under examination in the direction along the principal optical axis of the optical head with a simple configuration. [Means for solving the problem]

[0009] An ophthalmic apparatus for achieving the object of the present invention comprises an optical head, one or more parallel light projection units provided on the optical head for projecting parallel light onto the eye under examination, a displacement mechanism provided on the optical head for displacing the position and orientation of the parallel light projection unit, including at least one of the position and orientation, and an observation system provided on the optical head, having an objective lens and an image sensor, for capturing a bright spot image of the reflected light when the reflected light of the parallel light projected onto the eye under examination enters the image sensor through the objective lens, wherein, when a predetermined range is defined as a position at a distance from the eye under examination by the working distance of the objective lens in the direction along the principal optical axis of the optical head, the displacement mechanism can displace the parallel light projection unit to a position and orientation in which a bright spot image can be captured by the image sensor when the optical head is located outside the predetermined range. [Effects of the Invention]

[0010] This invention allows for an expansion of the detection range of the eye under examination in the direction along the principal optical axis of the optical head with a simple configuration. [Brief explanation of the drawing]

[0011] [Figure 1] This is a side view of the ophthalmic device according to the first embodiment. [Figure 2] This is a diagram showing the configuration of the optical head. [Figure 3] Figure IIIA shows the relationship between the Z-direction distance between the optical head and the eye under examination and the size of the bright spot image, and figure IIIB shows the relationship between this Z-direction distance and the size of the keratling image. [Figure 4] This is a front view of the keratin plate and two parallel light projection units located on the front of the optical head. [Figure 5] This is a schematic diagram of a displacement mechanism that displaces two parallel light projection units. [Figure 6] This is an explanatory diagram illustrating the normal position and orientation of two parallel light projection units. [Figure 7] This is an explanatory diagram illustrating the near-range position and orientation of one of the two parallel light projection units (13R). [Figure 8] It is an explanatory diagram for explaining the position and orientation for long range of the other one (13L) of the two parallel light projection units. [Figure 9] It is an explanatory diagram for explaining a modified example of the displacement of the two parallel light projection units by a displacement mechanism. [Figure 10] It is a functional block diagram of a control device. [Figure 11] It is an explanatory diagram for explaining an example of a method for calculating the Z-direction distance between the optical head and the eye to be examined based on the captured image. [Figure 12] It is a flowchart showing the measurement process of the eye characteristics of the eye to be examined, particularly the flow of Z alignment processing, by the ophthalmic device of the first embodiment. [Figure 13] It is an explanatory diagram showing a method for discriminating the Z-direction position of the optical head in the ophthalmic device 1 of the second embodiment. [Figure 14] It is a flowchart showing the flow of Z alignment processing by the alignment control unit of the second embodiment. [Figure 15] It is an explanatory diagram showing a method for discriminating the Z-direction position of the optical head in the ophthalmic device of the third embodiment. [Figure 16] It is a flowchart showing the flow of Z alignment processing by the alignment control unit of the third embodiment. [Figure 17] It is an explanatory diagram for explaining a method for calculating the Z-direction distance between the optical head and the eye to be examined by the alignment control unit of the third embodiment. [Figure 18] It is a diagram showing a modified example of the observation system. [Figure 19] It is an explanatory diagram for explaining the calculation of the Z-direction distance between the eye to be examined and the optical head when there is one parallel light projection unit.

Embodiments for Carrying Out the Invention

[0012] [First Embodiment] Figure 1 is a side view of the ophthalmic device 1 of the first embodiment. Of the mutually orthogonal XYZ directions (3 directions) in the figure, the Y direction is the vertical direction, the Z direction is the anterior-posterior direction (also called the working distance direction) parallel to the forward direction towards the eye E (subject) and the backward direction away from the subject, and the X direction is the left-right direction perpendicular to both the vertical and anterior-posterior directions.

[0013] <Overall configuration of ophthalmic device 1> The ophthalmic device 1 is an autorefractometer / keratometer capable of measuring the refractive power and corneal shape of the eye E being examined as ocular characteristics. This ophthalmic device 1 comprises a base 2, a face support unit 3, a drive mechanism 4, an optical head 5 (also called a measuring head or device body), and a display unit 6.

[0014] The drive mechanism 4 corresponds to the head movement mechanism of the present invention and is composed of an actuator (not shown), such as a motor. This drive mechanism 4 moves the optical head 5 in the XYZ direction relative to the base 2. This makes it possible to move the optical head 5 relative to the eye under examination E in the XYZ direction, thereby enabling XYZ alignment of the optical head 5 with respect to the eye under examination E.

[0015] The optical head 5 has a function for measuring the ocular characteristics (refractive power and corneal shape) of the eye E under examination. A display unit 6 is attached to the optical head 5. The optical head 5 also contains various optical systems (including an image sensor, various light sources, and various drive units) corresponding to the observation of the eye E under examination, the XYZ alignment of the optical head 5 with respect to the eye E under examination, and the measurement of refractive power and corneal shape, as well as a control device 9 (see Figure 2).

[0016] The display unit 6 may be, for example, a touch panel monitor. The display unit 6 is rotatably held by the optical head 5, and its position and orientation can be manually adjusted. The display unit 6 displays the observed image of the eye E acquired by the optical head 5, the measurement results of ocular characteristics such as refractive power and corneal shape of the eye E, a setting menu screen for making various settings, and an operation menu screen for making various operations.

[0017] The display surface of the display unit 6 accepts input operations by the examiner via touch, and therefore functions as an operating unit. Note that the ophthalmic device 1 may also be equipped with other known operating units besides the display unit 6.

[0018] <Configuration of Optical Head 5> Figure 2 shows the configuration of the optical head 5. As shown in Figure 2, the optical head 5 includes an observation system 12, a parallel light projection system 13, an XY alignment system 14, a target projection system 15, a measurement pattern projection system 16, and a light receiving system 17.

[0019] Observation system 12 is used for observing the anterior segment of the eye E under examination, and for photographing this anterior segment. Observation system 12 is an object-side telecentric optical system including an objective lens 12a having a principal optical axis O1 parallel to the Z direction. In this observation system 12, the following components are arranged in order from the eye E side along the principal optical axis O1: objective lens 12a, dichroic filter 12b, half mirror 12c, relay lens 12d, dichroic filter 12e, imaging lens 12f, and a CMOS (complementary metal oxide semiconductor) or CCD (Charge Coupled Device) type image sensor 12g. Observation system 12 also has an illumination light source (not shown). Since each component of observation system 12 is based on publicly known technology, a detailed explanation thereof is omitted.

[0020] The illumination light emitted from the illumination light source of the observation system 12 illuminates the anterior segment of the eye E under examination and is reflected from the anterior segment. This reflected light enters the objective lens 12a, passes through various parts of the observation system 12, and enters the imaging surface of the image sensor 12g. As a result, the reflected light is imaged by the image sensor 12g, and the image sensor 12g acquires an observation image (image data) of the anterior segment of the eye E under examination. The image sensor 12g outputs the observation image to the control device 9.

[0021] A keratin plate 12h and a keratin light source 12i are provided around the objective lens 12a, which are used to measure the corneal shape of the cornea Ec of the eye E under examination. The keratin plate 12h and the keratin light source 12i project a single or multiple (double in this embodiment) ring-shaped light beam onto the cornea Ec. The keratin light source 12i is a finite-distance illumination light source of the present invention that illuminates the eye E under examination from a finite distance. The ring-shaped light beam reflected by the cornea Ec enters the imaging surface of the image sensor 12g via the objective lens 12a and the dichroic filter 12b, etc. As a result, a keratin image 32 (see Figure 6) is captured by the image sensor 12g. The image sensor 12g outputs the keratin image 32 (image data) to the control device 9.

[0022] The parallel light projection system 13 is part of the configuration necessary for detecting the alignment state of the optical head 5 in the Z direction (direction along the principal optical axis O1) relative to the eye E under examination, and projects parallel light onto the eye E under examination. The detection of the alignment state here includes detecting the position of the optical head 5 in the Z direction and detecting the distance in the Z direction between the eye E under examination and the optical head 5. The parallel light projection system 13 includes two (or more than three) parallel light projection units 13R and 13L.

[0023] The parallel light projection units 13R and 13L are each held in a displaceable manner by a displacement mechanism 50 described later, and each has a light source 130 and a projection lens 131. Each light source 130 emits a light beam toward the projection lens 131. The light beam emitted from each light source 130 is converted into parallel light (collimated light) by each projection lens 131. Therefore, the parallel light projection units 13R and 13L each perform infinite distance illumination by emitting parallel light. The parallel light emitted from the parallel light projection units 13R and 13L is projected obliquely onto the cornea Ec of the eye under examination E and reflected by the cornea Ec.

[0024] The reflected parallel light reflected by the cornea Ec enters the objective lens 12a of the optical head 5 along the principal optical axis O1 when the Z-direction position of the optical head 5 relative to the eye E of the eye under examination satisfies predetermined conditions, and then enters the imaging surface of the image sensor 12g via the objective lens 12a and the dichroic filter 12b, etc. As a result, along with the keratling image 32 (see Figure 5), two bright spot images 30 (see Figure 6) corresponding to the reflected parallel light projected by the parallel light projection units 13R and 13L are captured by the image sensor 12g.

[0025] In Figure 3, the symbol IIIA shows the relationship between the Z-direction distance between the optical head 5 and the eye under examination E (the Z-direction position of the eye under examination E in the figure) and the size of the bright spot image 30, and the symbol IIIB shows the relationship between this Z-direction distance and the size of the keratling image 32. The symbol 12j in the figure is the aperture, which is positioned at the focal length of the objective lens 12a.

[0026] As shown by the symbol IIIA in Figure 3, when parallel light is projected onto the eye under examination E from the parallel light projection units 13R and 13L, which are infinite-distance illumination sources, and the reflected light is captured by the image sensor 12g of the observation system 12, which is an object-side telecentric optical system, the size of the bright spot image 30 remains approximately constant even when the Z-direction distance between the eye under examination E and the optical head 5 changes. On the other hand, as shown by the symbol IIIB in Figure 3, when a ring-shaped beam of light is projected onto the eye under examination E from the keratling light source 12i, which is a finite-distance illumination source, and the reflected light is captured by the image sensor 12g of the observation system 12, the size of the keratling image 32 changes according to the Z-direction distance between the eye under examination E and the optical head 5.

[0027] Returning to Figure 2, the image sensor 12g outputs an image 34 (image data) containing two bright spot images 30 and a keratin image 32 to the control device 9 when performing Z-alignment of the optical head 5 (see Figures 6 and 7). Then, as will be described in more detail later, the control device 9 calculates the Z-direction distance between the eye E under examination and the optical head 5 based on this image 34, and performs Z-alignment by moving the optical head 5 in the Z direction based on this calculation result.

[0028] The XY alignment system 14 is used to detect the alignment state of the optical head 5 in the X and Y directions relative to the eye E under examination. The XY alignment system 14 forms an optical path branched from the observation system 12 via a half mirror 12c. This XY alignment system 14 includes an alignment light source 14a and a projection lens 14b. The alignment light source 14a emits a light beam toward the projection lens 14b. The light beam emitted from the alignment light source 14a is converted into a parallel light beam by the projection lens 14b, reflected by the half mirror 12c, and projected onto the cornea Ec via a dichroic filter 12b and an objective lens 12a.

[0029] The light beam reflected by the cornea Ec enters the imaging surface of the image sensor 12g via the objective lens 12a and the dichroic filter 12b. As a result, a bright spot image for XY alignment is captured by the image sensor 12g, and the image sensor 12g outputs the captured image 34 (image data) of the bright spot image for XY alignment to the control device 9. This allows the display unit 6 to display the bright spot image for Y alignment. The control device 9 then drives the drive mechanism 4 based on the captured image 34 to adjust the position of the bright spot image in the X and Y directions, thereby performing XY alignment. Note that other known methods may be used for XY alignment.

[0030] The target projection system 15 fixes the line of sight of the eye E under examination and projects the light beam of the fixation target onto the fundus Ef of the eye E under examination in order to fixate or cloud the eye E under examination when objective measurement of the refractive power of the eye E under examination.

[0031] The target projection system 15 includes a target display unit 15a, a half mirror 15b, a relay lens 15c, a reflective mirror 15d, a focusing lens 15e (also called a moving lens), a relay lens 15f, a field lens 15g, a VCC lens 15h which is a variable cross cylinder lens, a reflective mirror 15i, dichroic filters 15j, 12b, and an objective lens 12a.

[0032] Furthermore, the target projection system 15 has an optical axis O2 parallel to the principal optical axis O1 described above, and the focusing lens 15e, relay lens 15f, field lens 15g, and VCC lens 15h are arranged on this optical axis O2.

[0033] The target display unit 15a may be any of the following display devices: a dot matrix liquid crystal display (LCD) or a matrix light-emitting diode (LED). This target display unit 15a displays a fixation target and emits the light beam of this target towards the half mirror 15b.

[0034] The light beam of the fixation target displayed on the target display unit 15a is reflected by the half mirror 15b, and then projected onto the eye under examination E via the relay lens 15c, the reflection mirror 15d, the focusing lens 15e, the relay lens 15f, the field lens 15g, the VCC lens 15h, the reflection mirror 15i, the dichroic filters 15j and 12b, and the objective lens 12a. This makes it possible to present the fixation target to the eye under examination E.

[0035] Furthermore, the target projection system 15 has a glare light source 15k used for glare testing of the eye E under examination. During the glare test, the glare light source 15k emits glare light to the half mirror 15b. As a result, the glare light is projected onto the eye E under examination via each part from the half mirror 15b to the objective lens 12a.

[0036] The focusing lens 15e is positioned to move back and forth along the optical axis O2 of the target projection system 15. The focusing lens 15e is moved back and forth along the optical axis O2 by the interlocking movement mechanism 27 described later. This allows the refractive power of the light beam of the fixation target to be changed, and thus the presentation distance of the fixation target to the eye under examination E can be changed. As a result, the eye under examination E can be made to fixate on or fogging the fixation target.

[0037] The VCC lens 15h has a pair of positive and negative cylindrical lenses. Each of the cylindrical lenses can rotate independently around the optical axis O2. The VCC lens 15h has the function of correcting (correcting) the cylindrical power (astigmatism power) and axial angle (astigmatism axis angle) among the aberrations caused by the refractive characteristics of the eye E being examined.

[0038] The measurement pattern projection system 16 projects a ring-shaped measurement pattern light beam (also called measurement light) onto the fundus Ef, which is used to measure the objective refractive power of the eye E under examination.

[0039] The measurement pattern projection system 16 includes a reflector measurement unit 16a, a relay lens 16b, an pupil ring 16c, a field lens 16d, a perforated prism 16e, a rotary prism 16f, a dichroic filter 15j, a dichroic filter 12b, and an objective lens 12a.

[0040] Furthermore, the measurement pattern projection system 16 has an optical axis O3 parallel to the principal optical axis O1 and optical axis O2 described above. A reflector measurement unit 16a, a relay lens 16b, an pupil ring 16c, a field lens 16d, and a perforated prism 16e are arranged on this optical axis O3.

[0041] The refractometer measurement unit 16a includes an LED light source 16h, a collimator lens 16i, a conical prism 16j, and a measurement pattern forming plate 16k. The LED light source 16h and the pupil ring 16c are positioned optically conjugate. The forming plate 16k and the fundus Ef are also positioned optically conjugate.

[0042] The reflector measurement unit 16a is positioned to move back and forth along the optical axis O3 of the measurement pattern projection system 16. The reflector measurement unit 16a is moved back and forth along the optical axis O3 by the interlocking movement mechanism 27, which will be described later.

[0043] The light beam emitted from the LED light source 16h is made into parallel light by the collimator lens 16i, and then emitted towards the relay lens 16b after passing through the conical prism 16j and the forming plate 16k. This light beam is projected onto the fundus Ef after passing through the relay lens 16b, pupil ring 16c, field lens 16d, the reflective surface of the perforated prism 16e, the rotary prism 16f, the dichroic filter 15j, the dichroic filter 12b, and the objective lens 12a. As a result, a ring-shaped measurement pattern of light beam is projected onto the fundus Ef. Note that the shape of this measurement pattern of light beam is distorted by the refractive power of the eye E under examination before being projected onto the fundus Ef.

[0044] The light-receiving system 17 receives the retinal reflected light of the measurement pattern projected onto the retinal Ef by the measurement pattern projection system 16. The light-receiving system 17 includes an objective lens 12a, dichroic filters 12b and 15j, a rotary prism 16f, a perforated prism 16e, a field lens 17a, a reflective mirror 17b, a relay lens 17c, a focusing lens 17d (also called a moving lens), a reflective mirror 17e, a dichroic filter 12e, an imaging lens 12f, and an image sensor 12g.

[0045] Furthermore, the light-receiving system 17 has an optical axis O4 parallel to the principal optical axis O1, optical axis O2, and optical axis O3 described above. A reflective mirror 17b, a relay lens 17c, a focusing lens 17d, and a reflective mirror 17e are arranged on this optical axis O4.

[0046] The focusing lens 17d is positioned to move back and forth along the optical axis O4 of the light-receiving system 17. The focusing lens 17d is moved back and forth along the optical axis O4 by the interlocking movement mechanism 27, which will be described later.

[0047] The retinal reflected light of the measurement pattern reflected by the retinal Ef enters the light-receiving surface of the image sensor 12g via the objective lens 12a, dichroic filters 12b, 15j, rotary prism 16f, perforated prism 16e, field lens 17a, reflective mirror 17b, relay lens 17c, focusing lens 17d (also called moving lens), reflective mirror 17e, dichroic filter 12e, and imaging lens 12f. The image sensor 12g captures the retinal reflected light and outputs a ring image (image data) to the control device 9.

[0048] The interlocking movement mechanism 27, although not shown in the diagram, includes a holding member that integrally holds (connects) the focusing lens 15e, the reflector measurement unit 16a, and the focusing lens 17d; a sliding mechanism that holds the holding member so that it can slide freely in a direction parallel to the principal optical axis O1 (each optical axis O2 to O4) (Z direction); and a drive mechanism such as a motor that moves the holding member forward and backward in the Z direction. As a result, the focusing lens 15e, the reflector measurement unit 16a, and the focusing lens 17d are moved in conjunction (integrally) along the Z direction by the interlocking movement mechanism 27.

[0049] <Parallel light projection units 13R, 13L> Figure 4 is a front view of the keratin plate 12h and parallel light projection units 13R and 13L, which are located on the front of the optical head 5. Figure 5 is a schematic diagram of the displacement mechanism 50 that displaces the parallel light projection units 13R and 13L, respectively.

[0050] As shown in Figures 4 and 5, the parallel light projection units 13R and 13L are provided on the keratin plate 12h. Specifically, when the keratin plate 12h is viewed from the front side in the Z direction (corresponding to one side of the principal optical axis O1), the parallel light projection units 13R and 13L are provided at the intersection of a straight line L (see Figure 4) that is perpendicular to the principal optical axis O1 and parallel to the X direction, and the inner ring of the double-ring keratin ring light source 12i. For this reason, the parallel light projection units 13R and 13L are provided at positions offset to both sides of the principal optical axis O1 in the left-right direction (X direction), and are point-symmetric with respect to the principal optical axis O1 when viewed from the front side in the Z direction and when viewed from the upper side in the Y direction. Note that the positions of the parallel light projection units 13R and 13L are not limited to the positions shown in Figure 4 and can be changed as appropriate.

[0051] The parallel light projection units 13R and 13L are each capable of changing their position and orientation by a displacement mechanism 50. Each displacement mechanism 50 is an electric actuator, such as a motor. Each displacement mechanism 50 can move the position of the parallel light projection units 13R and 13L in the X direction (perpendicular to the principal optical axis O1), i.e., it can slide them. Furthermore, each displacement mechanism 50 can rotate the parallel light projection units 13R and 13L about an axis parallel to the Y direction, i.e., it can change the orientation of the parallel light projection units 13R and 13L. The kerat plate 12h has an elongated hole 12k (see Figure 4) formed therein for sliding the parallel light projection units 13R and 13L in the X direction.

[0052] Each displacement mechanism 50 displaces at least one of the position and orientation of the parallel light projection units 13R and 13L under the control of the control device 9 described later. As a result, each displacement mechanism 50 can displace one of the parallel light projection units 13R and 13L between the normal position orientation and the near-range position orientation, and can displace the other of the parallel light projection units 13R and 13L between the normal position orientation and the far-range position orientation. The near-range position orientation (see Figure 7) and the far-range position orientation (see Figure 8) correspond to the displacement position orientations of the present invention.

[0053] The parallel light projection units 13R and 13L always project parallel light onto the eye E (cornea Ec) under examination, regardless of their position or orientation. The Z-direction position range of the optical head 5 that satisfies the conditions (hereinafter simply referred to as "imaging conditions") for the reflected light of this parallel light to pass through the objective lens 12a along the principal optical axis O1 and be imaged by the image sensor 12g is set individually for each position or orientation of the parallel light projection units 13R and 13L.

[0054] Figure 6 is an explanatory diagram illustrating the normal position and orientation of the parallel light projection units 13R and 13L. The upper part of Figure 6 (reference numerals 6A to 6C) shows the Z-direction position range of the optical head 5 when the reflected parallel light projected onto the cornea Ec from the parallel light projection units 13R and 13L in their normal positions is captured by the image sensor 12g. Figure 6 shows the captured images 34 (reference numerals 6D to 6H) obtained when the Z-direction position (Z-direction distance) of the optical head 5 relative to the eye E is changed, as shown by reference numerals 6A to 6C.

[0055] As indicated by the symbol IIIB in Figure 3 above, the size of the keratinized image 32 changes according to the change in the Z-direction distance between the eye E and the optical head 5 (see Figure 13 below). However, in Figure 6, to avoid complexity in the drawing, the size of the keratinized image 32 is shown as constant regardless of the Z-direction distance (the same applies to Figures 7 and 8 below). Also, in the upper part of Figure 6, the Z-direction position of the eye E is fixed while the Z-direction position of the eye E is changed, but in reality, the Z-direction position of the eye E is fixed while the Z-direction position of the optical head 5 is changed (the same applies to Figures 7, 8, 13, and 15 below). Furthermore, the symbol "WD" in Figure 6 indicates the working distance position, which is a known working distance (WD) of the objective lens 12a from the optical head 5 (objective lens 12a).

[0056] As shown in Figure 6, the Z-direction position range of the optical head 5 that satisfies imaging conditions corresponding to the normal position orientation of the parallel light projection units 13R and 13L is a predetermined range such that the eye under examination E is positioned within the range between detection limit WD(near) and detection limit WD(far) with respect to the working distance position WD. When the Z-direction position of the optical head 5 is within the predetermined range while the parallel light projection units 13R and 13L are displaced to their normal position orientation, that is, when the eye under examination E is positioned within the range between detection limit WD(near) and detection limit WD(far), two bright spot images 30 corresponding to the reflected light of the parallel light projected from the parallel light projection units 13R and 13L onto the eye under examination E appear in the captured image 34.

[0057] The two bright spot images 30 in the captured image 34 will be in focus when the Z-direction position of the optical head 5 is adjusted within a predetermined range so that the eye E under examination is positioned at or near the working distance position WD (see reference numerals 6B and 6F in Figure 6).

[0058] When the Z-direction position of the optical head 5 approaches the eye E under examination within a predetermined range, the eye E approaches the optical head 5 relatively, and the position of the eye E approaches the detection limit WD(near) within the range RA1 between the working distance position WD and the detection limit WD(near). In this case, the two bright spot images 30 in the captured image 34 become defocused (see reference numeral 6G in Figure 6). Then, when the optical head 5 approaches the eye E beyond the predetermined range, the eye E approaches the optical head 5 relatively to a position beyond the detection limit WD(near), as shown by reference numeral 6C in Figure 6, and the two bright spot images 30 in the captured image 34 disappear (see reference numeral 6H in Figure 6).

[0059] Conversely, when the Z-direction position of the optical head 5 moves away from the eye E within a predetermined range, the eye E moves relatively far away from the optical head 5, causing the position of the eye E to approach the detection limit WD(far) within the range RA2 between the working distance position WD and the detection limit WD(far). In this case as well, the two bright spot images 30 in the captured image 34 become defocused (see reference numeral 6E in Figure 6). Then, when the optical head 5 moves away from the eye E beyond the predetermined range, as shown by reference numeral 6A in Figure 6, the eye E moves relatively far away from the optical head 5 to a position beyond the detection limit WD(far), causing the two bright spot images 30 in the captured image 34 to disappear (see reference numeral 6D in Figure 6).

[0060] Furthermore, as indicated by the symbol IIIA in Figure 3 described above, when the parallel light projection units 13R and 13L are infinite illumination sources and the observation system 12 is an object-side telecentric optical system, the distance between the two bright spot images 30 in the captured image 34 remains approximately constant even when the Z-direction position of the optical head 5 changes.

[0061] Figure 7 is an explanatory diagram illustrating the near-range position and orientation of one of the parallel light projection units 13R and 13L (in this case, the parallel light projection unit 13R). The upper part of Figure 7 (reference numerals 7A to 7C) shows the state in which the Z-direction position (Z-direction distance) of the optical head 5 relative to the eye E is changed while the parallel light projection unit 13R is displaced to the near-range position and orientation, and the parallel light projection unit 13L is displaced to the far-range position and orientation. The lower part of Figure 7 (reference numerals 7D to 7F) shows an example of the captured image 34 obtained for each Z-direction position of the optical head 5 shown in the upper part of Figure 7.

[0062] As shown in Figure 7, the Z-direction position range of the optical head 5 that satisfies the imaging conditions corresponding to the near-range position and orientation of the parallel light projection unit 13R is the position range (hereinafter referred to as the near range) in which the eye under examination E is positioned between detection limit B1 and detection limit B2 in the figure. This near range partially overlaps with a predetermined range, but includes a range closer to the eye under examination E than this predetermined range. Detection limit B1 is set to be closer to the optical head 5 than detection limit WD(near) in the Z direction. Detection limit B2 is set between detection limit WD(near) and working distance position WD in the Z direction. When the Z-direction position of the optical head 5 is within the near range while the parallel light projection unit 13R is displaced to the near-range position and orientation, that is, when the eye under examination E is positioned within the range between detection limit B1 and detection limit B2, a bright spot image 30 (hereinafter referred to as the bright spot image 30n) corresponding to the reflected parallel light projected from the parallel light projection unit 13R appears in the captured image 34.

[0063] Furthermore, if the incident angle of parallel light changes due to the displacement of the parallel light projection unit 13R from its normal position to a position for close range (i.e., if the position of the parallel light projection unit 13R changes), the position of the bright spot image 30n in the captured image 34 will change from the position of the bright spot image 30 corresponding to the parallel light projection unit 13R in its normal position (see reference numeral 6F in Figure 6).

[0064] When the parallel light projection unit 13R is displaced to the near-range position, if the Z-direction position of the optical head 5 is further from the eye E than the near-range position, the eye E is positioned further from the optical head 5 than the detection limit B2, as shown by reference numeral 7A in Figure 7. The range RB1 in the figure indicates the range between the working distance position WD and the detection limit B2. In this case, the bright spot image 30n in the captured image 34 disappears, as shown by reference numeral 7D in Figure 7.

[0065] When the Z-direction position of the optical head 5 is within the overlapping range of the predetermined range and the near range, the eye under examination E is positioned within the range RB2 between the detection limit B2 and the detection limit WD(near), as shown by reference numeral 7B in Figure 7. In this case, as shown by reference numeral 7E in Figure 7, a bright spot image 30n appears in a defocused state within the captured image 34.

[0066] When the Z-direction position of the optical head 5 is within the range excluding the overlapping range with a predetermined range within the near range (hereinafter referred to as the "non-overlapping near range"), the eye E under examination is positioned within the range RB3 between the detection limit WD (near) and the detection limit B1, as shown by reference numeral 7C in Figure 7. In this case, a bright spot image 30n appears in the captured image 34, as shown by reference numeral 7F in Figure 7. If the bright spot image 30 shown in Figure 6 does not appear in the captured image 34 when the parallel light projection units 13R and 13L are in their normal positions, but the bright spot image 30n appears in the captured image 34 after the parallel light projection unit 13R is displaced to the near range position, then the optical head 5 is located within the non-overlapping near range, i.e., the eye under examination E is located within the range RB3.

[0067] Figure 8 is an explanatory diagram illustrating the far-range position and orientation of the other of the parallel light projection units 13R and 13L (in this case, the parallel light projection unit 13L). The upper part of Figure 8 (reference numerals 8A to 8C) shows the state in which the Z-direction position (Z-direction distance) of the optical head 5 relative to the eye E is changed while the position and orientation of both the parallel light projection unit 13L and the parallel light projection unit 13R are displaced to the far-range position and orientation. The lower part of Figure 8 (reference numerals 8D to 8F) shows an example of the captured image 34 obtained for each Z-direction position of the optical head 5 shown in the upper part of Figure 8.

[0068] As shown in Figure 8, the Z-direction position range of the optical head 5 that satisfies the imaging conditions corresponding to the far-range position and orientation of the parallel light projection unit 13L is the position range (hereinafter referred to as the far-range) in which the eye under examination E is positioned between detection limits C1 and C2 in the figure. This far-range partially overlaps with the predetermined range, but includes a range further from the eye under examination E than the predetermined range. Detection limit C1 is set to be further from the optical head 5 than detection limit WD(far) in the Z-direction. Detection limit C2 is set between the working distance position WD and detection limit WD(far) in the Z-direction. When the Z-direction position of the optical head 5 is within the far-range while the parallel light projection unit 13L is displaced to the far-range position and orientation, that is, when the eye under examination E is positioned within the range between detection limits C1 and C2, a bright spot image 30 (hereinafter referred to as the bright spot image 30f) corresponding to the reflected parallel light projected from the parallel light projection unit 13L appears in the captured image 34.

[0069] Furthermore, if the incident angle of parallel light changes due to the displacement of the parallel light projection unit 13L from its normal position to its far-range position (i.e., if the position of the parallel light projection unit 13L changes), the appearance position of the bright spot image 30f will change from the appearance position of the bright spot image 30 corresponding to the parallel light projection unit 13L in its normal position (see reference numeral 6F in Figure 6).

[0070] When the parallel light projection unit 13L is displaced to the far-range position, if the Z-direction position of the optical head 5 is closer to the eye under examination E than the far-range position, the eye under examination E is positioned closer to the optical head 5 than the detection limit C2, as shown by reference numeral 8A in Figure 8. The range RC1 in the figure indicates the range between the working distance position WD and the detection limit C2. In this case, the bright spot image 30f in the captured image 34 disappears, as shown by reference numeral 8D in Figure 8.

[0071] When the Z-direction position of the optical head 5 is within the overlapping range of the predetermined range and the far range, the eye under examination E is positioned within the range RC2 between the detection limit C2 and the detection limit WD(far), as shown by reference numeral 8B in Figure 8. In this case, a bright spot image 30f appears in the captured image 34 in a defocused state, as shown by reference numeral 8E in Figure 8.

[0072] When the Z-direction position of the optical head 5 is within the range excluding the overlapping range with a predetermined range within the far range (hereinafter referred to as the "non-overlapping far range"), the eye E under examination is positioned within the range RC3 between the detection limit WD(far) and the detection limit C1, as shown by reference numeral 8C in Figure 8. In this case, a bright spot image 30f appears in the captured image 34, as shown by reference numeral 8F in Figure 8. If the bright spot image 30 shown in Figure 6 does not appear in the captured image 34 when the parallel light projection units 13R and 13L are in their normal positions, but the bright spot image 30f appears in the captured image 34 after the parallel light projection unit 13L is displaced to the far range position, then the optical head 5 is located within the non-overlapping far range, i.e., the eye under examination E is located within the range RC3.

[0073] As shown in Figures 7 and 8, by displacing the parallel light projection unit 13R to a near-range position and the parallel light projection unit 13L to a far-range position, if the optical head 5 is located outside a predetermined range but within a non-overlapping far-range or non-overlapping far-range, a bright spot image 30n or bright spot image 30f will appear in the captured image 34. As a result, it becomes possible to determine whether the Z-direction position of the optical head 5 is within a non-overlapping near-range or non-overlapping near-range. In other words, it is possible to determine whether the eye under examination E is within the ranges RA1, RA2, RB3, or RC3 relative to the optical head 5.

[0074] Figure 9 is an explanatory diagram illustrating a modified example of the displacement of the parallel light projection units 13R and 13L by the displacement mechanism 50. The upper part of Figure 9 (reference numeral 8A) shows the state in which the parallel light projection unit 13L is displaced to the near-range position while the parallel light projection unit 13R remains in its normal position. The lower part of Figure 9 (reference numeral 8B) shows an example of an image 34 obtained with the parallel light projection units 13R and 13L in the position shown in the upper part of Figure 9.

[0075] In the examples shown in Figures 7 and 8, the parallel light projection unit 13R is displaced to a near-range position and the parallel light projection unit 13L is displaced from its normal position to a far-range position. However, only one of the parallel light projection units 13R or 13L may be displaced from its normal position to another position. For example, as shown in Figure 9, the parallel light projection unit 13R may be fixed in its normal position, while the parallel light projection unit 13L can be displaced to a near-range position in addition to the normal position and the far-range position. This reduces the number of displacement mechanisms 50 to one, thereby lowering costs.

[0076] Although not shown in the diagram, the parallel light projection unit 13L may be fixed in its normal position, while the parallel light projection unit 13R may be displaceable to a far-range position in addition to the normal position and the near-range position.

[0077] <Functions of the control device 9> Figure 10 is a functional block diagram of the control device 9. As shown in Figure 10, the control device 9 comprehensively controls the operation of each part of the ophthalmic device 1 to perform XYZ alignment of the optical head 5 with respect to the eye E under examination and measurement of the eye characteristics of the eye E under examination. The control device 9 is connected to the face support unit 3, the drive mechanism 4, the various systems 12 to 17 of the optical head 5, the display unit 6, the keratin light source 12i, and the displacement mechanism 50.

[0078] The control device 9 includes an arithmetic circuit composed of various processors and memory. These processors include CPUs (Central Processing Units), GPUs (Graphics Processing Units), ASICs (Application Specific Integrated Circuits), and programmable logic devices [e.g., SPLDs (Simple Programmable Logic Devices), CPLDs (Complex Programmable Logic Devices), and FPGAs (Field Programmable Gate Arrays)]. The various functions of the control device 9 may be implemented by a single processor, or by multiple processors of the same or different types.

[0079] The control device 9 functions as an alignment control unit 40, an eye characteristic measurement control unit 42, and an eye characteristic calculation unit 44 by executing a control program stored in a memory unit (not shown).

[0080] Before the start of eye measurement of the eye E under examination, the alignment control unit 40 controls the observation system 12, keratling light source 12i, parallel light projection system 13, XY alignment system 14, and target projection system 15, etc., to perform XY alignment and Z alignment of the optical head 5 for the eye E under examination.

[0081] A known method is used for XY alignment. The alignment control unit 40 first controls the observation system 12, XY alignment system 14, and target projection system 15, etc., to perform XY alignment detection to detect the relative position of the optical head 5 in the XY direction with respect to the eye E under examination. Then, based on the detection result of the XY alignment detection, the alignment control unit 40 drives the drive mechanism 4 to move the optical head 5 in the XY direction, thereby performing XY alignment of the optical head 5 with respect to the eye E under examination.

[0082] On the other hand, when the alignment control unit 40 performs Z-alignment of the optical head 5, it initiates the emission of parallel light from the parallel light projection units 13R and 13L, which are initially displaced to their normal positions, the emission of a ring-shaped light beam from the keratin light source 12i, and the imaging of the anterior segment (cornea Ec) of the eye E under examination by the observation system 12.

[0083] Next, the alignment control unit 40 determines whether or not there are two bright spot images 30 in the captured image 34 output from the image sensor 12g of the observation system 12. If the Z-direction position of the optical head 5 is within a predetermined range, two bright spot images 30 will appear in the captured image 34 (see reference numerals 6E to 6G in Figure 6), but if it is outside the predetermined range, two bright spot images 30 will not appear in the captured image 34 (see reference numerals 6D and 6H in Figure 6). As a result, the alignment control unit 40 can determine whether or not the Z-direction position of the optical head 5 is within a predetermined range (whether or not the eye under examination E is located within ranges RA1 and RA2) based on the presence or absence of the two bright spot images 30.

[0084] Then, if the alignment control unit 40 determines that the Z-direction position of the optical head 5 is not within a predetermined range, it drives the displacement mechanism 50 to displace the parallel light projection unit 13R to a near-range position and the parallel light projection unit 13L to a far-range position, and then determines whether or not bright spot images 30n and 30f exist in the captured image 34 output from the image sensor 12g. If the Z-direction position of the optical head 5 is within the non-overlapping near-range (when the eye E under examination is located within range RB3), a bright spot image 30n appears in the captured image 34 (see Figure 7), and if the Z-direction position of the optical head 5 is within the non-overlapping far-range (when the eye E under examination is located within range RC3), a bright spot image 30f appears in the captured image 34 (see Figure 8). As a result, the optical head 5 within the non-overlapping near-range and non-overlapping far-range (eye E located within ranges RB3 and RC3) can be detected, thus expanding the detection range of the eye E under examination in the Z direction by the optical head 5.

[0085] The alignment control unit 40 drives the drive mechanism 4 to adjust the optical head 5's position away from the eye E when a bright spot image 30n appears in the captured image 34. The alignment control unit 40 also drives the drive mechanism 4 to adjust the optical head 5's position closer to the eye E when a bright spot image 30f appears in the captured image 34. The alignment control unit 40 continues adjusting the optical head 5's position until the bright spot image 30n or 30f disappears from the captured image 34. This ensures that the optical head 5 is positioned within a predetermined range.

[0086] Next, the alignment control unit 40 drives the displacement mechanism 50 to displace the parallel light projection units 13R and 13L to their normal positions, and then determines whether or not there are two bright spot images 30 in the captured image 34 output from the image sensor 12g. This confirms that the optical head 5 has been adjusted to a predetermined position.

[0087] Furthermore, if the eye under examination E is approaching the optical head 5 beyond the detection limit B1, or if the eye under examination E is moving away from the optical head 5 beyond the detection limit C1, bright spot images 30n and 30f will not appear in the captured image 34 even if the parallel light projection unit 13R is displaced to a near-range position and the parallel light projection unit 13L is displaced to a far-range position.

[0088] In such cases, the alignment control unit 40 cancels the automatic XY alignment and Z alignment (auto-alignment), and then drives the displacement mechanism 50 to return the parallel light projection units 13R and 13L to their normal positions. Then, in response to the input of a manual position adjustment operation of the optical head 5 relative to the display surface of the display unit 6, which functions as an operation unit, the alignment control unit 40 drives the drive mechanism 4 to move the optical head 5 (manual alignment). As a result, the optical head 5 is positioned within a predetermined range.

[0089] The alignment control unit 40 calculates the distance in the Z direction between the optical head 5 and the eye E under examination based on the captured image 34, if the position of the optical head 5 in the Z direction is within a predetermined range.

[0090] Figure 11 is an explanatory diagram illustrating an example of a method for calculating the Z-direction distance between the optical head 5 and the eye under examination E based on the captured image 34. As shown in Figure 11, the distance LA between the two bright spot images 30 in the captured image 34 is approximately constant regardless of the Z-direction distance between the optical head 5 and the eye under examination E because the parallel light projection units 13R and 13L are infinite-distance illumination sources (see symbol IIIA in Figure 3 described above). On the other hand, the distance LB between the inner ring images of the keratin ring image 32 in the captured image 34 increases or decreases depending on the Z-direction distance between the optical head 5 and the eye under examination E because the keratin ring light source 12i is a finite-distance illumination source (see symbol IIIB in Figure 3 described above).

[0091] The alignment control unit 40 calculates the Z-direction distance between the optical head 5 and the eye under examination E in a known manner based on the ratio of the distance LA between the two bright spot images 30 and the distance LB between the keratinized images 32. In this case, the alignment control unit 40 functions as the distance calculation unit of the present invention. Based on the calculation result of this Z-direction distance, the alignment control unit 40 drives the drive mechanism 4 to move the optical head 5 in the Z-direction, thereby performing Z-alignment of the optical head 5 with respect to the eye under examination E.

[0092] Returning to Figure 10, the eye characteristic measurement control unit 42 controls the observation system 12, keratinizing light source 12i, measurement pattern projection system 16, and target projection system 15, etc., after the alignment described above is completed, to perform keratometry to measure the corneal shape of the eye E under examination, and refractometry to measure the refractive power of the eye E under examination. The eye characteristic calculation unit 44 calculates the corneal shape of the eye E under examination if keratometry is performed, and calculates the refractive power of the eye E under examination if refractometry is performed.

[0093] For example, in keratometry of the eye E under examination, the eye characteristic measurement control unit 42 turns on the keratography ring light source 12i to project a ring-shaped beam of light onto the cornea Ec, and causes the image sensor 12g to image the ring-shaped beam of light reflected by the cornea Ec. Next, the eye characteristic calculation unit 44 calculates the corneal shape of the eye E under examination (corneal refractive power, corneal astigmatism, and corneal astigmatism axis angle, etc.) using a known method based on the keratography ring image 32 in the captured image 34 output from the image sensor 12g.

[0094] In the refraction measurement of the eye E under examination, a preliminary measurement and a final measurement are performed. In the preliminary measurement, the eye characteristic measurement control unit 42 controls the target projection system 15 (target display unit 15a) to present a fixation target to the eye E under examination. Next, the eye characteristic measurement control unit 42 controls the measurement pattern projection system 16 (LED light source 16h and rotary prism 16f, etc.) to project a ring-shaped measurement pattern light beam onto the fundus Ef, and causes the light receiving system 17 (image sensor 12g) to capture the fundus reflected light (ring image) reflected by the fundus Ef.

[0095] Then, the eye characteristic calculation unit 44 calculates the provisional spherical power and astigmatism power of the eye E under examination using a known method, based on the captured ring image output from the image sensor 12g. Based on the calculation results of the spherical power and astigmatism power in this provisional measurement, the eye characteristic measurement control unit 42 drives the interlocking movement mechanism 27 to move the focusing lens 15e, the refractor measurement unit 16a, and the focusing lens 17d to the position of the transmitted spherical power. This provisional measurement process may be repeated multiple times.

[0096] In this measurement, the eye characteristic measurement control unit 42 drives the interlocking movement mechanism 27 to move the focusing lens 15e from the position determined in the preliminary measurement to the clouding position, thereby promoting clouding of the eye E under examination. The eye characteristic measurement control unit 42 then controls the measurement pattern projection system 16 and the light receiving system 17 in the same manner as in the preliminary measurement to project a ring-shaped measurement pattern light beam onto the fundus Ef and to capture a ring image with the image sensor 12g. Next, the eye characteristic calculation unit 44 calculates the refractive power (spherical power, astigmatism power, astigmatism axis angle) of the eye E under examination using a known method based on the ring image and the amount of movement of the focusing lens 15e.

[0097] <Operation of the ophthalmic device 1 in the first embodiment> Figure 12 is a flowchart showing the flow of the measurement process of the ocular characteristics of the eye E examined by the ophthalmic device 1 of the first embodiment, particularly the Z-alignment process.

[0098] As shown in Figure 12, in the initial state when the ophthalmic device 1 is powered on, the parallel light projection units 13R and 13L are set to their normal positions (step S1). Then, after the subject's face is supported by the face support unit 3, when the examiner inputs a measurement start operation on the operation menu screen of the display unit 6, the alignment control unit 40 starts the XYZ alignment of the optical head 5 with respect to the eye E under examination (step S2).

[0099] The alignment control unit 40 controls each part of the optical head 5 to perform XY alignment detection of the optical head 5 with respect to the eye E under examination using a known method.

[0100] Furthermore, the alignment control unit 40 initiates the emission of parallel light from the parallel light projection units 13R and 13L, the emission of a ring-shaped light beam from the keratin light source 12i, and the imaging of the anterior segment (cornea Ec) of the eye E under examination by the observation system 12 (step S3).

[0101] First, the alignment control unit 40 performs a first determination process to determine whether or not two bright spot images 30 appear in the captured image 34 output from the image sensor 12g of the observation system 12, thereby determining whether or not the Z-direction position of the optical head 5 is within a predetermined range (step S4). If two bright spot images 30 appear in the captured image 34, the alignment control unit 40 proceeds to step S11, which will be described later (YES in step S4).

[0102] On the other hand, if the alignment control unit 40 does not see two bright spot images 30 in the captured image 34, it drives the displacement mechanism 50 to displace the parallel light projection unit 13R to a near-range position and displace the parallel light projection unit 13L to a far-range position and position, performing a first displacement process (NO in step S4, step S5). Next, the alignment control unit 40 performs a second determination process to determine whether or not there are bright spot images 30n and 30f in the captured image 34 output from the image sensor 12g (step S6).

[0103] Then, the alignment control unit 40 drives the drive mechanism 4 to adjust the optical head 5 away from the eye E when a bright spot image 30n appears in the captured image 34, and drives the drive mechanism 4 to adjust the optical head 5 closer to the eye E when a bright spot image 30f appears in the captured image 34, initiating a head position adjustment process (YES in step S6, step S7). This head position adjustment process continues until the bright spot image 30n or 30f in the captured image 34 disappears (NO in step S8). If the bright spot image 30n or 30f in the captured image 34 disappears (YES in step S8), the alignment control unit 40 drives the displacement mechanism 50 to return the parallel light projection units 13R and 13L to their normal positions (step S9), and then returns to step S4.

[0104] Furthermore, if the alignment control unit 40 determines NO in step S6, it switches from auto-alignment to manual alignment and displaces the parallel light projection units 13R and 13L to their normal positions. Then, in response to the examiner's manual position adjustment operation of the optical head 5, the alignment control unit 40 drives the drive mechanism 4 to move the optical head 5 within a predetermined range (step S10). This manual position adjustment operation causes two bright spot images 30 to appear in the captured image 34 (step S4).

[0105] After the optical head 5 is positioned within a predetermined range, the alignment control unit 40 calculates the Z-direction distance between the optical head 5 and the eye under examination E based on the distance LA between two bright spot images 30 and the distance LB between the keratinized images 32 in the captured image 34 (YES in step S4, step S11). Next, based on the calculation result of this Z-direction distance, the alignment control unit 40 drives the drive mechanism 4 to perform Z-alignment of the optical head 5 with respect to the eye under examination E (step S12). The alignment control unit 40 also drives the drive mechanism 4 to perform XY alignment of the optical head 5 with respect to the eye under examination E based on the XY alignment detection results described above.

[0106] Once XYZ alignment is complete, the eye characteristic measurement control unit 42 controls the observation system 12, keratinizing light source 12i, measurement pattern projection system 16, target projection system 15, etc., to perform keratin and refractory measurements of the eye E under examination. In addition, the eye characteristic calculation unit 44 calculates the corneal shape of the eye E under examination during keratin measurement and calculates the refractive power of the eye E under examination during refractory measurement. As a result, eye characteristic measurement data (corneal shape, refractive power) of the eye E under examination is obtained (step S13).

[0107] As described above, in the ophthalmic apparatus 1 of the first embodiment, the displacement mechanism 50 makes it possible to displace at least one of the parallel light projection units 13R and 13L to a near-range position and a far-range position, thereby determining whether the Z-direction position of the optical head 5 is within the non-overlapping near-range or the non-overlapping far-range (whether the eye E under examination is within range RB3 or range RC3). This makes it possible to extend the detection range of the eye E under examination in the Z-direction of the optical head 5 with a simple configuration. As a result, Z-alignment of the optical head 5 can be performed even if the Z-direction position of the optical head 5 is not within a predetermined range. Furthermore, since it is no longer necessary to provide an optical lever type Z-alignment system on the optical head 5 as in the conventional method, the ophthalmic apparatus 1 can be made lower cost and smaller.

[0108] [Second Embodiment] Figure 13 is an explanatory diagram showing a method for determining the Z-direction position of the optical head 5 in the ophthalmic device 1 of the second embodiment.

[0109] In the ophthalmic apparatus 1 of the first embodiment described above, if the optical head 5 is not within a predetermined range, the parallel light projection unit 13R is displaced to a near-range position and the parallel light projection unit 13L is displaced to a far-range position. In contrast, as shown in Figure 13, in the ophthalmic apparatus 1 of the second embodiment, if the optical head 5 is not within a predetermined range, the parallel light projection units 13R and 13L are simultaneously displaced in the X direction until two bright spot images 30 appear in the captured image 34.

[0110] Furthermore, the ophthalmic apparatus 1 of the second embodiment has basically the same configuration as the ophthalmic apparatus 1 of the first embodiment, except that the method of displacing the position and orientation of the parallel light projection units 13R and 13L when the optical head 5 is not within a predetermined range is different. For this reason, components that are functionally or structurally identical to those of the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0111] The displacement mechanism 50 of the second embodiment is capable of performing a displacement process that slides the parallel light projection units 13R and 13L in the X direction while maintaining the orientation (incidence angle of parallel light) of the parallel light projection units 13R and 13L in their normal position (see reference numeral XIIIA in Figure 13). This displacement process includes an approach process and a separation process. As shown by reference numeral XIIIB in Figure 13, in the approach process, the parallel light projection units 13R and 13L are simultaneously displaced in the approach direction, moving closer to each other in the X direction. Also, as shown by reference numeral XIIIC in Figure 13, in the separation process, the parallel light projection units 13R and 13L are simultaneously displaced in the separation direction, moving further apart from each other in the X direction.

[0112] The orientation of the parallel light projection units 13R and 13L is maintained during approach and separation processes. Therefore, if the incident angle of parallel light in the normal position is θw, the incident angle of parallel light during approach is θn, and the incident angle of parallel light during separation is θf, then the incident angles θw, θn, and θf are all constant (θw=θn=θf).

[0113] As shown by labels XIIIA and XIIID in Figure 13, when the parallel light projection units 13R and 13L are set in their normal positions, two bright spot images 30 appear in the captured image 34 only when the Z-direction position of the optical head 5 is within a predetermined range (i.e., when the eye under examination E is positioned between the detection limit WD(near) and the detection limit WD(far)), similar to the first embodiment described above.

[0114] As shown by the symbol XIIIB in Figure 13, during the approach process, as the parallel light projection units 13R and 13L move closer to each other, the Z-direction position range of the optical head 5 that satisfies the above-mentioned imaging conditions gradually approaches the eye E under examination. As a result, the detection limit WD(near1) and detection limit WD(far1) gradually approach the optical head 5 from their normal position. Therefore, if the Z-direction position of the optical head 5 is closer to the eye E under examination than the predetermined range, that is, if the eye E under examination is relatively close to the optical head 5 to a position beyond the detection limit WD(near), the eye E under examination will be positioned within the range between the detection limit WD(near1) and detection limit WD(far1) during the approach process, causing two bright spot images 30 to appear in the captured image 34 as shown by the symbol XIIIE in Figure 13.

[0115] As shown by the symbol XIIIC in Figure 13, during the separation process, as the parallel light projection units 13R and 13L move away from each other, the Z-direction position range of the optical head 5 that satisfies the above imaging conditions gradually moves away from the eye E under examination. As a result, the detection limit WD(near2) and detection limit WD(far2) gradually move away from the optical head 5 from their normal position. Therefore, if the Z-direction position of the optical head 5 is further from the eye E under examination than a predetermined range, that is, if the eye E under examination is relatively far from the optical head 5 to a position beyond the detection limit WD(far), the eye E under examination will be positioned within the range between the detection limit WD(near2) and detection limit WD(far2) during the separation process, causing two bright spot images 30 to appear in the captured image 34 as shown by the symbol XIIIF in Figure 13.

[0116] As previously described, the angle of incidence of parallel light incident on the eye E from the parallel light projection units 13R and 13L during approach and separation processing is constant (θw=θn=θf). Furthermore, the observation system 12 is an object-side telecentric optical system. Therefore, if we define the distance in the X direction between two bright spot images 30 appearing in the captured image 34 obtained in the normal position and orientation as "tw", the distance in the X direction between two bright spot images 30 appearing in the captured image 34 during approach processing as "tn", and the distance in the X direction between two bright spot images 30 appearing in the captured image 34 during separation processing as "tf", then these distances are constant (tw=tn=tf).

[0117] Figure 14 is a flowchart showing the flow of the Z-alignment process by the alignment control unit 40 of the second embodiment. Note that the processes from step S1 to step S4 are the same as in the first embodiment, so a detailed explanation is omitted here.

[0118] As shown in Figure 14, in the second embodiment, if NO is found in step S4 (when two bright spot images 30 do not appear in the captured image 34), the alignment control unit 40 drives the displacement mechanism 50 to start either the approach process or the separation process (in this case, the approach process) (step S20). This starts the displacement of the parallel light projection units 13R and 13L in the approach direction.

[0119] After the start of the approach process, the alignment control unit 40 repeatedly determines whether or not two bright spot images 30 appear in the captured image 34 output from the image sensor 12g (NO in both steps S21 and S22). If the first condition that two bright spot images 30 appear in the captured image 34 during the approach process is met (YES in step S21), the alignment control unit 40 performs a process to stop the approach process (step S23) and then proceeds to step S11.

[0120] On the other hand, the alignment control unit 40 stops the approach process if the second condition is met (YES in step S22) that two bright spot images 30 do not appear in the captured image 34 even when the parallel light projection units 13R and 13L are displaced to a predetermined limit position in the approach direction (corresponding to the limit position on one side of the present invention) (i.e., when the parallel light projection units 13R and 13L are displaced to a predetermined limit position in the approach direction), the alignment control unit 40 stops the approach process.

[0121] Next, the alignment control unit 40 drives the displacement mechanism 50 to start separating the parallel light projection units 13R and 13L (step S24). This starts the displacement of the parallel light projection units 13R and 13L in the direction of separation.

[0122] After the separation process begins, the alignment control unit 40 repeatedly determines whether or not two bright spot images 30 appear in the captured image 34 output from the image sensor 12g (NO in both steps S25 and S26). If the first condition that two bright spot images 30 appear in the captured image 34 during the separation process is met (YES in step S25), the alignment control unit 40 performs a process to stop the separation process (step S27) and then proceeds to step S11.

[0123] On the other hand, the alignment control unit 40 stops the separation process if the second condition is met (YES in step S26) that two bright spot images 30 do not appear in the captured image 34 even when the parallel light projection units 13R and 13L undergoing separation processing are displaced to a predetermined limit position in the separation direction (corresponding to the "limit position on the other direction side" and "stop position" in the present invention).

[0124] In such cases, even if the parallel light projection units 13R and 13L are displaced by the displacement mechanism 50, two bright spot images 30 cannot be made to appear in the captured image 34, so the alignment control unit 40 stops the auto-alignment. Then, the alignment control unit 40 drives the drive mechanism 4 in response to the examiner's input for manual position adjustment of the optical head 5, thereby performing manual alignment of the optical head 5 (step S28). This makes it possible to make two bright spot images 30 appear in the captured image 34, and then the process proceeds to step S11.

[0125] If two bright spot images 30 appear in the captured image 34, the alignment control unit 40 calculates the Z-direction distance between the optical head 5 and the eye under examination E based on the distance LA between the two bright spot images 30 and the distance LB between the keratinized images 32 (step S11). Thus, in the second embodiment, unlike the first embodiment, the Z-direction distance can be calculated without adjusting the position of the optical head 5 within a predetermined range. The subsequent processing is the same as in the first embodiment, so a detailed explanation will be omitted.

[0126] As described above, in the ophthalmic apparatus 1 of the second embodiment, the same effects as in the first embodiment can be obtained by simultaneously displacing the position and orientation of the parallel light projection units 13R and 13L using the displacement mechanism 50. Furthermore, in the ophthalmic apparatus 1 of the second embodiment, the Z-direction distance between the optical head 5 and the eye under examination E can be calculated even if the optical head 5 is not within a predetermined range, so Z-alignment can be completed in a shorter time.

[0127] [Third Embodiment] Figure 15 is an explanatory diagram showing a method for determining the Z-direction position of the optical head 5 in the ophthalmic device 1 of the third embodiment.

[0128] In the ophthalmic apparatus 1 of the second embodiment described above, when the optical head 5 is not within a predetermined range, the parallel light projection units 13R and 13L are simultaneously displaced in the approaching or separating direction, thereby causing two bright spot images 30 to appear in the captured image 34. In contrast, as shown in Figure 15, in the ophthalmic apparatus 1 of the third embodiment, when the optical head 5 is not within a predetermined range, the parallel light projection units 13R and 13L are simultaneously rotated in opposite directions.

[0129] Furthermore, the ophthalmic apparatus 1 of the third embodiment has basically the same configuration as the ophthalmic apparatus 1 of each of the above embodiments, except that the method of displacing the position and orientation of the parallel light projection units 13R and 13L when the optical head 5 is not within a predetermined range is different. For this reason, components that are functionally or structurally identical to those of each of the above embodiments are denoted by the same reference numerals and their descriptions are omitted.

[0130] The displacement mechanism 50 of the third embodiment is capable of performing displacement processing to rotate the parallel light projection units 13R and 13L, which are in their normal position and orientation (see reference numeral XVA in Figure 15), in opposite directions around a rotation axis parallel to the Y direction. This displacement processing includes angle-increasing rotation processing and angle-decreasing rotation processing.

[0131] As shown by the symbol XVB in Figure 15, the angle-increasing rotation process rotates the parallel light projection units 13R and 13L in an angle-increasing direction (corresponding to the first rotation direction of the present invention) that increases the angle of incidence of parallel light to the eye E under examination. This makes it possible to make the incident angle θn larger than the incident angle θw (θn > θw).

[0132] As shown by the symbol XVC in Figure 15, the angle reduction rotation process rotates the parallel light projection units 13R and 13L in an angle reduction direction (corresponding to the second rotation direction of the present invention) that reduces the angle of incidence of parallel light to the eye E under examination. This makes it possible to make the incident angle θf smaller than the incident angle θw (θf < θw).

[0133] As shown by the labels XVA and XVD in Figure 15, when the parallel light projection units 13R and 13L are set in their normal positions, two bright spot images 30 appear in the captured image 34 only when the Z-direction position of the optical head 5 is within a predetermined range (i.e., when the eye under examination E is positioned within the range between detection limit WD(near) and detection limit WD(far)), similar to the embodiments described above.

[0134] As shown by the symbol XVB in Figure 15, as the incident angle θn of parallel light to the eye E during the angle-increasing rotation process becomes larger than the incident angle θw, the position range in the Z direction of the optical head 5 that satisfies the above imaging conditions gradually approaches the eye E. In this case, the detection limit WD(near1) and detection limit WD(far1) gradually approach the optical head 5 from their positions in the normal position and orientation.

[0135] Therefore, when the Z-direction position of the optical head 5 is closer to the eye E under examination than a predetermined range, that is, when the eye E under examination is relatively close to the optical head 5 to a position beyond the detection limit WD(near), the eye E under examination is positioned within the range between the detection limit WD(near1) and the detection limit WD(far1) during the angle-increasing rotation process, causing two bright spot images 30 to appear in the captured image 34 as shown by the symbol XVE in Figure 15. Note that since the incident angle θn is greater than the incident angle θw, the distance tn between the two bright spot images 30 is greater than the distance tw (tn>tw).

[0136] As shown by the symbol XVC in Figure 15, as the incident angle θf of parallel light to the eye E becomes smaller than the incident angle θw during the angle reduction rotation process, the position range in the Z direction of the optical head 5 that satisfies the above imaging conditions gradually moves away from the eye E. In this case, the detection limit WD(near2) and detection limit WD(far2) gradually move away from the position in the normal position orientation relative to the optical head 5.

[0137] Therefore, when the Z-direction position of the optical head 5 is further from the eye E under examination than a predetermined range, that is, when the eye E under examination is relatively far from the optical head 5 to a position beyond the detection limit WD(far), the eye E under examination is positioned within the range between the detection limit WD(near2) and the detection limit WD(far2) during the angle reduction rotation process, causing two bright spot images 30 to appear in the captured image 34 as shown by the symbol XVF in Figure 15. Note that since the incident angle θf is smaller than the incident angle θw, the distance tf between the two bright spot images 30 becomes smaller than the distance tw (tf <tw)。

[0138] Figure 16 is a flowchart showing the flow of the Z-alignment process by the alignment control unit 40 of the third embodiment. Note that the processes from step S1 to step S4 are the same as in each of the embodiments described above, so a detailed explanation is omitted here.

[0139] As shown in Figure 16, in the third embodiment, if the determination process in step S4 is NO (no two bright spot images 30 appear in the captured image 34), the alignment control unit 40 drives the displacement mechanism 50 to start either an angle-increasing rotation process or an angle-decreasing rotation process (in this case, an angle-increasing rotation process) (step S30). This starts the rotation of the parallel light projection units 13R and 13L in the angle-increasing direction, and the angle of incidence of parallel light to the eye E under examination gradually increases.

[0140] After the angle-increasing rotation process begins, the alignment control unit 40 repeatedly determines whether or not two bright spot images 30 appear in the captured image 34 output from the image sensor 12g (NO in both steps S31 and S32). Then, if the first condition that two bright spot images 30 appear in the captured image 34 during the angle-increasing rotation process is met (YES in step S31), the alignment control unit 40 executes a process to stop the angle-increasing rotation process (step S33).

[0141] Next, the alignment control unit 40 obtains angle information indicating the angle of incidence of parallel light to the eye E under examination during the stopping process, based on the rotation angles of the parallel light projection units 13R and 13L during the stopping process (step S34), and then proceeds to step S11. The angle information can be calculated, for example, based on the detection result of a rotation angle detection sensor (not shown) that detects the rotation angles of the parallel light projection units 13R and 13L.

[0142] On the other hand, the alignment control unit 40 stops the angle-increasing rotation process if the second condition is met (YES in step S32) when the parallel light projection units 13R and 13L, which are undergoing angle-increasing rotation processing, rotate to a predetermined limit position (corresponding to the limit position on one side of the present invention) in the angle-increasing rotation direction, and two bright spot images 30 do not appear in the captured image 34.

[0143] Next, the alignment control unit 40 drives the displacement mechanism 50 to start the angle-decreasing rotation process of the parallel light projection units 13R and 13L (step S35). As a result, the parallel light projection units 13R and 13L start rotating in the angle-decreasing direction, and the angle of incidence of parallel light on the eye E under examination gradually decreases.

[0144] The alignment control unit 40 repeatedly determines whether two bright spot images 30 appear in the captured image 34 output from the image sensor 12g after the angle reduction rotation process has started (NO in both steps S36 and S37). If the first condition that two bright spot images 30 appear in the captured image 34 during the angle reduction rotation process is met (YES in step S36), the alignment control unit 40 performs a process to stop the angle reduction rotation process (step S38), and then proceeds to step S11 via step S34 as described above.

[0145] On the other hand, the alignment control unit 40 stops the angle reduction rotation process if the second condition is met (YES in step S37) when the parallel light projection units 13R and 13L, which are undergoing angle reduction rotation processing, rotate to a predetermined limit position in the angle reduction direction (corresponding to the "limit position on the other direction side" and "stop position" in the present invention) and two bright spot images 30 do not appear in the captured image 34.

[0146] In such cases, even if the parallel light projection units 13R and 13L are rotated by the displacement mechanism 50, two bright spot images 30 cannot be made to appear in the captured image 34, so the alignment control unit 40 stops the auto-alignment. Then, the alignment control unit 40 drives the drive mechanism 4 in response to the examiner's input for manual position adjustment of the optical head 5, thereby performing manual alignment of the optical head 5 (step S39). This makes it possible to make two bright spot images 30 appear in the captured image 34, and then proceeds to step S11 via step S34.

[0147] If two bright spot images 30 appear in the captured image 34, the alignment control unit 40 starts calculating the Z-direction distance between the optical head 5 and the eye E under examination.

[0148] Figure 17 is an explanatory diagram illustrating the calculation method of the Z-direction distance between the optical head 5 and the eye under examination E by the alignment control unit 40 of the third embodiment. When the parallel light projection units 13R and 13L are rotated from their normal position by rotation processing such as angle-increasing rotation processing and angle-decreasing rotation processing, the angle of incidence of parallel light to the eye under examination E changes. For this reason, it is necessary to convert the interval LA between two bright spot images 30 in the captured image 34 obtained during rotation processing to the interval LA between two bright spot images 30 in the captured image 34 obtained in the normal position.

[0149] As shown in Figure 17, the alignment control unit 40 calculates the curvature (radius of curvature) r of the cornea Ec based on the following equation [Equation 1]. In Figure 17, the symbol 2θ represents the incident angle of parallel light, which is obtained as angle information in step S34 of Figure 16 as described above. Also, the symbol h in Figure 17 represents the bright spot height (corneal virtual image height), which can be obtained based on the bright spot information of the anterior segment of the eye E under examination.

[0150]

number

[0151] The distance LA between the two bright spot images 30 in the captured image 34 depends on parameters such as the angle "θ" and the curvature "r" of the corneal Ec. Therefore, the alignment control unit 40 converts the distance LA obtained during the rotation process into the distance LA in the normal position and orientation based on these parameters.

[0152] Returning to Figure 16, the alignment control unit 40 calculates the Z-direction distance between the optical head 5 and the eye under examination E based on the converted interval LA and interval LB, similar to the above embodiments (step S11). Thus, in the third embodiment as well, the Z-direction distance can be calculated without adjusting the optical head 5 to a predetermined range, similar to the second embodiment. The subsequent processing is the same as in the above embodiments, so a detailed explanation will be omitted.

[0153] As described above, in the ophthalmic apparatus 1 of the third embodiment, the same effect as in the second embodiment can be obtained by simultaneously rotating the parallel light projection units 13R and 13L using the displacement mechanism 50.

[0154] [others] Figure 18 shows a modified example of the observation system 12. In each of the embodiments described above, the case in which the observation system 12 is an object-side telecentric optical system was used as an example, but as shown in Figure 18, the observation system 12 does not have to be an object-side telecentric optical system. Even in this case, the Z-direction position of the optical head 5 can be determined.

[0155] Figure 19 is an explanatory diagram illustrating the calculation of the Z-direction distance between the eye E under examination and the optical head 5 when the optical head 5 is equipped with only one parallel light projection unit 13R. In each of the above embodiments, the optical head 5 is equipped with two (or more) parallel light projection units 13R, 13L, but the number may be just one.

[0156] If the optical head 5 is equipped with only one parallel light projection unit 13R (or parallel light projection unit 13L), an image 34 like the one shown in Figure 19 is obtained. In this case, the alignment control unit 40 calculates the Z-direction distance between the optical head 5 and the eye under examination E based on the ratio of the interval LA1, which is the distance from the center position C of the keratling image 32 to the bright spot image 30, to the interval LB described above. Note that the distance from the bright spot to the bright spot image 30 for XY alignment may be used as the interval LA1, although it is not shown in the figure. This allows Z-alignment to be performed in the same manner as in each of the above embodiments.

[0157] In each of the above embodiments, an autorefractor / keratometer was used as an example of the ophthalmic device 1 of the present invention, but the present invention is applicable to various known ophthalmic devices that perform Z-alignment of various optical heads (in particular, various ophthalmic devices equipped with an object-side telecentric optical system).

[0158] Some or all of the above embodiments may also be described as follows, but are not limited to the following:

[0159] [Additional note 1] Optical head and The optical head is provided with one or more parallel light projection units that project parallel light onto the eye under examination, A displacement mechanism provided on the optical head for displacing the position and orientation, including at least one of the position and orientation of the parallel light projection unit, An observation system provided on the optical head, having an objective lens and an image sensor, wherein when the reflected light of the parallel light projected onto the eye under examination enters the image sensor through the objective lens, the image sensor captures a bright spot image of the reflected light. Equipped with, In an ophthalmic device in which, when a predetermined range is defined as a position located at a distance from the eye to be examined by the working distance of the objective lens in a direction along the principal optical axis of the optical head, the displacement mechanism is capable of displacing the parallel light projection unit to a position and orientation in which the image sensor can capture the bright spot image when the optical head is located outside the predetermined range.

[0160] [Additional note 2] The displacement mechanism is capable of displacing the position and orientation of the parallel light projection unit between the normal position and a displaced position and orientation different from the normal position. The normal position and orientation is the position and orientation in which the image sensor can capture the bright spot image when the optical head is located within the predetermined range. The ophthalmic apparatus according to Appendix 1, wherein the displacement position and orientation is the position and orientation that enables the image sensor to capture the bright spot image when the optical head is located at least outside the range.

[0161] [Additional note 3] The system comprises two parallel light projection units, The ophthalmic apparatus according to Appendix 2, wherein the displacement mechanism is capable of displacing at least one of the two parallel light projection units between the normal position and the displaced position.

[0162] [Additional note 4] The aforementioned displacement position and orientation are When the optical head is positioned in a near range that includes at least a range closer to the eye under examination than the predetermined range, the near range position and orientation that enables the image sensor to capture the bright spot image, When the optical head is located in a far range that includes at least a range further from the eye to be examined than the predetermined range and is different from the near range, the far range position and orientation that enables the image sensor to capture the bright spot image, Includes, The ophthalmic apparatus according to Appendix 3, wherein the displacement mechanism is capable of displacing one of the two parallel light projection units between the normal position and the near-range position, and the other of the two parallel light projection units between the normal position and the far-range position.

[0163] [Additional note 5] Equipped with a control unit, The control unit, A first determination process for determining whether the bright spot image is captured by the image sensor when the two parallel light projection units are displaced to the normal position and orientation, If the first determination process determines no, the displacement mechanism is driven to displace one of the two parallel light projection units to the near-range position and the other of the two parallel light projection units to the far-range position and the first displacement process, A second determination process determines whether or not the bright spot image is captured by the image sensor after the completion of the first displacement process, An ophthalmic device as described in Appendix 4, which performs the following actions.

[0164] [Additional note 6] The optical head is provided with a head movement mechanism for moving the optical head, The control unit, If the second determination process determines that the bright spot image corresponding to one of the parallel light projection units has been captured, the head movement mechanism is driven to move the optical head away from the eye under examination until the bright spot image disappears; if the second determination process determines that the bright spot image corresponding to the other of the parallel light projection units has been captured, the head position adjustment process is driven to move the optical head closer to the eye under examination until the bright spot image disappears; A second displacement process is performed to displace the two parallel light projection units to the normal position after the completion of the head position adjustment process, A process to execute the first determination process after the completion of the second displacement process, An ophthalmic device as described in Appendix 5, which performs the following actions.

[0165] [Additional note 7] The optical head is provided with a head movement mechanism for moving the optical head, The optical head is equipped with an operating unit that receives input for manual position adjustment operations, The ophthalmic apparatus according to Appendix 5 or 6, wherein if the control unit determines no in the second determination process, it drives the head movement mechanism in response to the manual position adjustment operation on the operating unit to displace the optical head.

[0166] [Additional note 8] Equipped with a control unit, The position and orientation include a normal position and orientation in which the image sensor can capture the bright spot image when the optical head is located within the predetermined range. The control unit, A determination process for determining whether the bright spot image is captured by the image sensor when the parallel light projection unit is displaced to the normal position and orientation, If the determination process determines no, the displacement mechanism is driven to displace the parallel light projection unit from its normal position and orientation. A stop process is performed to stop the displacement process when a first condition is met during the displacement process, such as when the bright spot image is captured by the image sensor or when the parallel light projection unit is displaced to a predetermined stop position. An ophthalmic device as described in Appendix 1, which performs the following actions.

[0167] [Additional note 9] The system comprises two parallel light projection units, When the optical head is viewed from one direction of the principal optical axis, the two parallel light projection units are in a point-symmetric positional relationship with respect to the principal optical axis. The displacement mechanism allows the two parallel light projection units to be displaced in an approaching direction, where they move closer together, and in an separating direction, where they move further apart. The control unit drives the displacement mechanism in the displacement process to displace the two parallel light projection units in either the approaching direction or the separating direction, and when the two parallel light projection units have been displaced to the limit position in the one direction, it displaces the two parallel light projection units in the other direction opposite to the one direction. The ophthalmic apparatus according to Appendix 8, wherein the stopping position is the limit position in which the two parallel light projection units can be displaced to the other direction.

[0168] [Additional Note 10] The system comprises two parallel light projection units, When the optical head is viewed from one direction of the principal optical axis, the two parallel light projection units are in a point-symmetric positional relationship with respect to the principal optical axis. The displacement mechanism allows the two parallel light projection units to rotate in a first rotational direction in which the angle of incidence of the parallel light to the eye under examination increases, and in a second rotational direction in which the angle of incidence decreases. The control unit drives the displacement mechanism in the displacement processing to rotate the two parallel light projection units in either the first rotation direction or the second rotation direction, and when the two parallel light projection units have rotated to the limit position in the one direction, it rotates the two parallel light projection units in the other direction opposite to the one direction. The ophthalmic apparatus according to Appendix 8, wherein the stopping position is the limit position in which the two parallel light projection units can be rotated to the other direction.

[0169] [Additional Note 11] When the stop process is executed because the second condition is met, an operating unit that receives input for manual position adjustment of the optical head, A head movement mechanism that moves the optical head in response to the manual position adjustment operation input to the operation unit, An ophthalmic device as described in any one of the appendices 8 to 10, comprising:

[0170] [Additional Note 12] Equipped with a finite-distance illumination light source that provides illumination at a finite distance, The observation system is an object-side telecentric system, and captures an image of the eye under examination onto which the parallel light from the parallel light projection unit and the illumination light from the finite-distance illumination source are projected. An ophthalmic apparatus according to any one of the appendices 1 to 11, comprising a distance calculation unit that calculates the distance between the optical head and the eye under examination based on the captured image including the bright spot image and the image of the illumination light.

[0171] [Additional Note 13] The ophthalmic apparatus according to Appendix 12, wherein the finite-distance illumination source is a keratinizing light source. [Explanation of Symbols]

[0172] 1…Ophthalmology equipment 2…Bass 3…Face support section 4…Drive mechanism 5…Optical head 6…Display section 9...Control device 12… Observation-based 12a…Objective lens 12b... Dichroic filter 12c... Half mirror 12d… Relay lens 12e... Dichroic filter 12f...imaging lens 12g…image sensor 12h... Geratolite 12i...Keratling light source 12k…long hole 13…Z-alignment optics 13L, 13R… Parallel light projection unit 14…XY Alignment System 14a... Alignment light source 14b…Projection lens 15...Optotype projection system 15a...Optotype display section 15b... Half mirror 15c… Relay lens 15d... Reflective mirror 15e… ​​Focusing lens 15f… Relay lens 15g…Field lens 15h...VCC lens 15i…Reflective mirror 15j... Dichroic filter 15k... Glare light source 16…Measurement pattern projection system 16a...Ref measurement unit 16b…Relay lens 16c... Eye Ring 16d…Field lens 16e...Perforated prism 16f... Rotary prism 16h…LED light source 16i...Collimator lens 16j... Conical prism 16k…forming plate 17...Light receiving system 17a…Field lens 17b... Reflective mirror 17c… Relay lens 17d... Focusing lens 17e... Reflective mirror 27... Interlocking movement mechanism 30, 30n, 30f... Bright spot image 32... Keratling statue 34… Captured image 40… Alignment Control Unit 42…Eye characteristic measurement and control unit 44...Eye characteristic calculation section 50…Displacement mechanism 130...Light source 131…projection レンズ C…Central position E...Being blinded Ec…cornea Ef…fundus O1…Main Axis O2~O4…Optical axis

Claims

1. Optical head and The optical head is provided with one or more parallel light projection units that project parallel light onto the eye under examination, A displacement mechanism provided on the optical head for displacing the position and orientation, including at least one of the position and orientation of the parallel light projection unit, An observation system provided on the optical head, having an objective lens and an image sensor, wherein when the reflected light of the parallel light projected onto the eye under examination enters the image sensor through the objective lens, the image sensor captures a bright spot image of the reflected light. Equipped with, In an ophthalmic device in which, when a predetermined range is defined as a position located at a distance from the eye to be examined by the working distance of the objective lens in a direction along the principal optical axis of the optical head, the displacement mechanism is capable of displacing the parallel light projection unit to a position and orientation in which the image sensor can capture the bright spot image when the optical head is located outside the predetermined range.

2. The displacement mechanism is capable of displacing the position and orientation of the parallel light projection unit between the normal position and a displaced position and orientation different from the normal position. The normal position and orientation is the position and orientation in which the image sensor can capture the bright spot image when the optical head is located within the predetermined range. The ophthalmic apparatus according to claim 1, wherein the displacement position and orientation is the position and orientation that enables the image sensor to capture the bright spot image when the optical head is located at least outside the range.

3. The system comprises two parallel light projection units, The ophthalmic apparatus according to claim 2, wherein the displacement mechanism is capable of displacing at least one of the two parallel light projection units between the normal position and the displaced position.

4. The aforementioned displacement position and orientation are When the optical head is positioned in a near range that includes at least a range closer to the eye under examination than the predetermined range, the near range position and orientation that enables the image sensor to capture the bright spot image, When the optical head is located in a far range that includes at least a range further from the eye to be examined than the predetermined range and is different from the near range, the far range position and orientation that enables the image sensor to capture the bright spot image, Includes, The ophthalmic apparatus according to claim 3, wherein the displacement mechanism is capable of displacing one of the two parallel light projection units between the normal position and the near-range position, and the other of the two parallel light projection units between the normal position and the far-range position.

5. Equipped with a control unit, The control unit, A first determination process for determining whether the bright spot image is captured by the image sensor when the two parallel light projection units are displaced to the normal position and orientation, If the first determination process determines no, the displacement mechanism is driven to displace one of the two parallel light projection units to the near-range position and the other of the two parallel light projection units to the far-range position and the first displacement process, A second determination process determines whether or not the bright spot image is captured by the image sensor after the completion of the first displacement process, The ophthalmic apparatus according to claim 4, which performs the following:

6. The optical head is provided with a head movement mechanism for moving the optical head, The control unit, If the second determination process determines that the bright spot image corresponding to one of the parallel light projection units has been captured, the head movement mechanism is driven to move the optical head away from the eye under examination until the bright spot image disappears; if the second determination process determines that the bright spot image corresponding to the other of the parallel light projection units has been captured, the head position adjustment process is driven to move the optical head closer to the eye under examination until the bright spot image disappears; A second displacement process is performed to displace the two parallel light projection units to the normal position after the completion of the head position adjustment process, A process to execute the first determination process after the completion of the second displacement process, The ophthalmic apparatus according to claim 5, which performs the following:

7. The optical head is equipped with an operating unit that receives input for manual position adjustment operations, The ophthalmic apparatus according to claim 6, wherein if the control unit determines no in the second determination process, it drives the head movement mechanism in response to the manual position adjustment operation on the operation unit to displace the optical head.

8. Equipped with a control unit, The position and orientation include a normal position and orientation in which the image sensor can capture the bright spot image when the optical head is located within the predetermined range. The control unit, A determination process for determining whether the bright spot image is captured by the image sensor when the parallel light projection unit is displaced to the normal position and orientation, If the determination process determines no, the displacement mechanism is driven to displace the parallel light projection unit from its normal position and orientation. A stop process is performed to stop the displacement process when a first condition is met during the displacement process, such as when the bright spot image is captured by the image sensor or when the parallel light projection unit is displaced to a predetermined stop position. An ophthalmic apparatus according to claim 1, which performs the following:

9. The system comprises two parallel light projection units, When the optical head is viewed from one direction of the principal optical axis, the two parallel light projection units are in a point-symmetric positional relationship with respect to the principal optical axis. The displacement mechanism allows the two parallel light projection units to be displaced in an approaching direction, where they move closer together, and in an separating direction, where they move further apart. The control unit drives the displacement mechanism in the displacement processing to displace the two parallel light projection units in either the approaching direction or the separating direction, and when the two parallel light projection units have been displaced to the limit position in the one direction, it displaces the two parallel light projection units in the other direction opposite to the one direction. The ophthalmic apparatus according to claim 8, wherein the stopping position is the limit position in which the two parallel light projection units can be displaced to the other direction.

10. The system comprises two parallel light projection units, When the optical head is viewed from one direction of the principal optical axis, the two parallel light projection units are in a point-symmetric positional relationship with respect to the principal optical axis. The displacement mechanism allows the two parallel light projection units to rotate in a first rotational direction in which the angle of incidence of the parallel light to the eye under examination increases, and in a second rotational direction in which the angle of incidence decreases. In the displacement processing, the control unit drives the displacement mechanism to rotate the two parallel light projection units in either the first rotation direction or the second rotation direction, and when the two parallel light projection units have rotated to the limit position in the one direction, it rotates the two parallel light projection units in the other direction opposite to the one direction. The ophthalmic apparatus according to claim 8, wherein the stopping position is the limit position in which the two parallel light projection units can be rotated to the other direction.

11. When the stop process is executed because the second condition is met, an operating unit that receives input for manual position adjustment of the optical head, A head movement mechanism that moves the optical head in response to the manual position adjustment operation input to the operation unit, The ophthalmic apparatus according to claim 8, comprising:

12. Equipped with a finite-distance illumination light source that provides illumination at a finite distance, The observation system is an object-side telecentric system, and captures an image of the eye under examination onto which the parallel light from the parallel light projection unit and the illumination light from the finite-distance illumination source are projected. An ophthalmic apparatus according to any one of claims 1 to 11, further comprising a distance calculation unit that calculates the distance between the optical head and the eye under examination based on the captured image including the bright spot image and the image of the illumination light.

13. The ophthalmic apparatus according to claim 12, wherein the finite-distance illumination light source is a keratinizing light source.

Images