JP2015119915A - Ophthalmologic apparatus and control method of ophthalmologic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ophthalmologic apparatus capable of expanding a range of a quick and highly accurate autoalignment.SOLUTION: The ophthalmologic apparatus includes: an optical system for applying light to a subject's eye and receiving the reflected light from the subject's eye; identification means for identifying shapes of a plurality of index images that the optical system has acquired from the reflected light; and determination means for determining the alignment state between the optical system and the subject's eye on the basis of a difference in the shapes of the plurality of index images that the identification means has identified.

Description

The present invention relates to an ophthalmologic apparatus and a control method thereof.

  In an ophthalmic apparatus that measures the eye characteristics of a conventional eye to be examined, a light beam is projected onto the cornea of the eye to be examined, and a reflected image from the cornea is detected by a light receiving element, thereby obtaining an alignment state between the eye and the apparatus optical system. It is known to perform auto alignment. Here, accurate positional information in the three-dimensional direction between the eye and the apparatus optical system is obtained from the positional relationship of a plurality of index images that have received a plurality of light beams obtained by separating a plurality of reflected light beams from the cornea by a pair of light deflection members. Patent Document 1 discloses an ophthalmologic apparatus that detects the above and performs fine alignment.

JP-A-9-84760

  Here, when the eye moves, at least one of the plurality of index images is vignetted by an optical member having a pair of light deflection members, and the vignetting index image may not be detected. At this time, conventionally, since there is no difference between the plurality of index images, it is impossible to recognize which index image is the vignetting index image among the plurality of index images. For this reason, in such a case, fine alignment could not be performed.

  In order to solve the above-described problems, an ophthalmologic apparatus according to the present invention includes an optical system that irradiates a subject's eye with light and receives reflected light from the subject's eye, and the optical system obtains the reflected light from the reflected light. Identification means for identifying at least two index images among the plurality of index images, and determination means for determining an alignment state between the optical system and the eye to be examined based on a difference between the identified index images. It is characterized by that.

  In order to solve the above-described problem, an ophthalmologic apparatus control method according to the present invention irradiates a subject's eye with light from an optical system, receives reflected light from the subject's eye, and receives the reflected light. Identifying at least two index images among a plurality of index images obtained from light, and determining an alignment state between the optical system and the eye to be examined based on a difference between the identified index images. Features.

  According to the present invention, at least two index images among a plurality of index images can be identified. As a result, even if at least one of the plurality of index images is vignetted and no vignetting index image is detected, it is possible to recognize which index image the vignetting index image is among the plurality of index images. Can do. For this reason, even in such a case, fine alignment can be performed.

It is an external view of an eye refractive power measuring apparatus. It is an arrangement plan of an optical system of a measurement part. It is a perspective view of an alignment prism diaphragm. It is an anterior ocular segment observation image. It is a system block diagram of an eye refractive power measuring device. It is a figure explaining the mode of the light-receiving part in the state where the Z position of the eye to be examined is ideal. It is a figure explaining the mode of the light-receiving part in the state where the Z position of the eye to be examined is far. It is the figure explaining the mode of the light-receiving part in the state where the Z position of the eye to be examined is close. It is a figure explaining the mode of the light-receiving part in the state where the eye to be examined is eccentric in the X direction. It is a figure explaining the relationship between the shape in case the shape of a diaphragm differs, and a luminescent spot image. It is a figure explaining the relationship between the shape in case the shape of an aperture | diaphragm is the same, and a luminescent spot image. It is a figure for demonstrating the processing flow of auto alignment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

(Device body)
FIG. 1 is a schematic configuration diagram of an eye refractometer as an eye refractive power measuring apparatus according to the present embodiment. The X frame 102 is movable in the left-right direction (the direction perpendicular to the paper surface in the drawing, hereinafter referred to as the X-axis direction) with respect to the base 100. The drive mechanism in the X-axis direction includes an X-axis drive motor 103 fixed on the base 100, a feed screw (not shown) connected to the motor output shaft, and a movement on the feed screw in the X-axis direction. A nut (not shown) fixed to 102 is formed. As the X-axis drive motor 103 rotates, the X frame 102 moves in the X-axis direction via a feed screw and a nut.

  The Y frame 106 is movable in the vertical direction (the vertical direction in the figure, hereinafter referred to as the Y-axis direction) with respect to the X frame 102. The drive mechanism in the Y-axis direction includes a Y-axis drive motor 104 fixed on the X frame 102, a Y-feed screw 105 connected to the motor output shaft, and a Y-feed screw 105 that can move in the Y-axis direction. A Y nut 114 fixed to the frame 106 is used. As the Y-axis drive motor 104 rotates, the Y frame 106 moves in the Y-axis direction via the Y feed screw 105 and the Y nut 114.

  The Z frame 107 is movable in the front-rear direction (the left-right direction in the drawing, hereinafter referred to as the Z-axis direction) with respect to the Y frame 106. The drive mechanism in the Z-axis direction includes a Z-axis drive motor 108 fixed on the Z frame 107, a Z feed screw 109 connected to the motor output shaft, and a Y frame 106 that can move on the feed screw in the Z axis direction. It is comprised with the Z nut 115 fixed to. As the Z-axis drive motor 108 rotates, the Z frame 107 moves in the Z-axis direction via the Z feed screw 109 and the Z nut 115. On the Z frame 107, a measurement unit 110 for measuring eye refractive power is fixed as a unique information acquisition unit.

  A light source (not shown) for alignment and a light source unit 111 for measuring corneal curvature are provided at the end of the measurement unit 110 on the subject side.

  The frame 100 is provided with a joystick 101 that is an operation member for aligning the measurement unit 110 with respect to the eye to be examined. During alignment, the joystick 101 is tilted in the left-right direction (X-axis direction) and the front-rear direction (Z-axis direction) to adjust the position in each direction, and by rotating the joystick 101, the joystick 101 is moved in the vertical direction (Y-axis direction). Adjust the position.

  In addition, the above drive mechanism and the structure relevant to this function as a drive means which drives a measurement means with respect to an eye to be examined for alignment in this invention. The measurement unit 110 functions as a measurement unit that irradiates the eye to be measured with a measurement light beam and measures the state of the eye to be examined based on the reflected light from the eye to be examined.

  When the eye refractive power is measured, the subject puts his chin on the chin rest 112 and presses the forehead against a forehead portion of a face rest frame (not shown) fixed to the frame 100. The position of the eye to be examined can be fixed. The position of the chin rest 112 can be adjusted in the Y-axis direction by the chin rest driving mechanism 113 according to the size of the face of the subject.

  An LCD monitor 116, which is a display member for observing the eye to be examined, is provided at the end of the measurement unit 110 on the examiner side and can display measurement results and the like.

(Configuration of eye refractive power measuring head)
FIG. 2 is a layout diagram of the optical system inside the measurement unit 110. On the optical path 01 of the first optical system from the eye refractive power measurement light source 201 to the eye E, a lens 202, a diaphragm 203 almost conjugate with the pupil Ep of the eye E, a perforated mirror 204, a diffusion plate 222, And the lens 205 are sequentially arranged. Through the optical path 01, an index light beam by an irradiation light beam having a wavelength of 880 nm is irradiated to the fundus of the eye to be examined. Further, a dichroic mirror 206 that totally reflects infrared and visible light having a wavelength of less than 880 nm from the eye E side and partially reflects a light beam having a wavelength of 880 nm or more is disposed.

  On the optical path 02 in the reflection direction of the perforated mirror 204, a ring-shaped stop 207 having a ring-shaped slit almost conjugate with the pupil Ep, a light beam splitting prism 208, a lens 209, and an image sensor 210 are sequentially arranged. Yes. The above-described optical system is for measuring eye refractive power, and the light beam emitted from the measurement light source 201 is primarily imaged by the lens 202 before the objective lens 205 while the light beam is reduced by the stop 203. Then, the light passes through the objective lens 205 and the dichroic mirror 206 and is projected onto the pupil center of the eye E to be examined.

  The light beam projected as the measurement light beam is reflected by the fundus oculi Er, and the fundus reflection light is incident on the objective lens 205 again through the periphery of the pupil. The incident light beam is reflected around the perforated mirror 204 after passing through the objective lens 205. The reflected light flux is pupil-separated through a second optical system including the objective lens 205 by a ring diaphragm 207 and a light beam spectroscopic prism 208 that are substantially conjugate with the eye pupil Ep to be examined, and is ring-coupled to the light receiving surface of the image sensor 210. Projected as an image.

  If the eye E is a normal eye, the ring-shaped image output is a predetermined circle, and the near-sighted eye has a smaller circle than the normal eye, and the far-sighted eye has a larger circle than the normal eye and is projected.

  When the subject eye E has astigmatism, the ring image becomes an ellipse, and the angle formed by the horizontal axis and the major or minor axis of the ellipse is the astigmatic axis angle. The refractive power is obtained based on the coefficient of the ellipse.

  On the other hand, in the reflection direction of the dichroic mirror 206, a fixation target projection optical system and an alignment light receiving optical system shared for anterior eye portion observation and alignment detection of the eye to be examined are arranged.

  On the optical path 03 of the fixation target projection optical system, a lens 211, a dichroic mirror 212, a lens 213, a folding mirror 214, a lens 215, a fixation target 216, and a fixation target illumination light source 217 are sequentially arranged. . At the time of fixation fixation, the light flux projected from the fixation target illumination light source 217 illuminates the fixation target 216 from the back side, and passes through the lens 215, the folding mirror 214, the lens 213, the dichroic mirror 212, and the lens 211. Projected onto the fundus Er of the eye E.

  The lens 215 can be moved in the optical axis direction by a fixation induction motor 224 in order to guide the diopter of the eye E and realize a cloudy state.

(Configuration of alignment light receiving optical system)
On the optical path 04 in the reflection direction of the dichroic mirror 212, an alignment prism diaphragm 223, a lens 218, and an imaging element 220 that can be inserted and removed by an alignment prism diaphragm insertion / removal solenoid 511 (see FIG. 5) are sequentially arranged.

  Further, the anterior ocular segment illumination light sources 221a and 221b installed in the vicinity of the apparatus measurement unit are illumination light sources for the anterior segment of the eye E having a wavelength of about 780 nm. The luminous flux of the anterior segment image of the eye E illuminated by the anterior segment illumination light sources 221a and 221b passes through the anterior segment reflected light path 04 and is imaged on the image sensor 220.

  FIG. 3 shows the shape of the alignment prism diaphragm 223. Three apertures 223a, 223b, and 223c are provided in a disc-shaped diaphragm, and alignment prisms 301a and 301b that transmit light beams having a wavelength of about 880 nm are attached to the dichroic mirror 212 side of the apertures 223b and 223c on both sides. Yes.

  This apparatus can detect the bright spot for alignment of the eye to be inspected and observe the transillumination image by combining the insertion and removal of the diffusion plate 222 and the alignment prism diaphragm 223 described above.

  At the time of detecting the alignment bright spot, the alignment prism diaphragm 223 and the diffusion plate 222 are inserted into the optical path by the respective insertion / removal mechanisms. The light source for alignment detection is also used as the measurement light source 201 for measuring the eye refractive power, and the configuration for guiding the light beam emitted from the measurement light source 201 as the alignment light beam to the eye to be examined is the measurement light source. 201 includes the light projecting means of the present invention. Yes. Further, the position where the diffusion plate 222 is inserted is the primary image formation position by the projection lens 202 of the measurement light source 201 and is inserted at the focal position of the lens 205. As a result, the image of the measurement light source 201 is once formed on the diffusion plate 222 and becomes a secondary light source, and is projected from the lens 205 toward the eye E as a thick parallel light beam. The parallel light beam is reflected by the eye cornea Ef to be examined, and the light beam passes through the central opening 223a of the alignment prism diaphragm and the alignment prisms 301a and 301b and is converged by the lens 218.

  The bright spots converged on the image sensor 220 are superimposed on the above-described anterior segment image and imaged as three alignment bright spots in the pupil region. The configuration for guiding the alignment light beam to the image sensor 220 functions as a light receiving unit that receives the alignment light beam reflected from the eye to be examined. The light beam transmitted through the alignment prism 301a is refracted downward, and the light beam transmitted through the alignment prism 301b is refracted upward. The eye E can be aligned based on the positional relationship of the light flux through these diaphragms.

  Further, when the alignment prism diaphragm 223 is inserted on the light receiving optical path, the light beam of the anterior segment image forms an image on the light receiving sensor surface of the image sensor 220 via the central opening 223a. Therefore, the amount of light beam that forms an image on the image sensor 220 is smaller than when the alignment prism diaphragm 223 is off the optical path. Therefore, in this apparatus, in order to obtain an anterior ocular segment image having an optimum luminance, the light amount of the anterior ocular illumination light source 221 is changed in synchronization with the insertion / removal of the alignment prism diaphragm 223.

  FIG. 4 shows an anterior ocular segment observation image displayed on the LCD 116 during alignment. The eye E and its surroundings are illuminated by the external illumination light sources 221a and 221b, and the reflection image of the external illumination light source 221 is captured on the iris of the examination eye E as external eye bright spot images 221a ′ and 221b ′. Has been. Further, the corneal reflection light flux of the measurement light reflected by the cornea Ef is divided by the openings 223a, 223b, 223c of the alignment prism diaphragm 223 and the prisms 301a, 301b, and is imaged as index images Ta, Tb, Tc by the image sensor 220. Has been. The alignment prism diaphragm 223 is disposed on the optical path of the reflected light. The image sensor 220 functions as a detecting unit that photoelectrically detects the index image formed by the light projecting unit and the light receiving unit. The detection means detects the light beam reflected by the eye to be examined as a plurality of index images having at least two different shapes. The light projecting unit and the light receiving unit together constitute an optical system that irradiates light to the eye to be examined and receives reflected light from the eye to be examined. In addition, since alignment can be performed using at least two index images, the alignment prism diaphragm 223 may include at least two openings.

(Control means)
FIG. 5 is a system block diagram. A system control unit 501 that controls the entire system includes a program storage unit, a data storage unit that stores data for correcting eye refractive power values, an input / output control unit that controls input / output with various devices, An arithmetic processing unit that calculates data obtained from the device is included.

  The system control unit 501 is connected to a joystick 101 that instructs the measurement unit 110 to align with the eye E and to start measurement. On the joystick 101, there are a tilt angle detection input 502 for detecting a tilt angle when tilted back and forth, left and right, an encoder input 503 for detecting a rotation amount when rotated, and a measurement start button 504 to be depressed at the start of measurement. Arranged as an input configuration. In addition, a print button, a chin rest up / down button, and the like are arranged on the operation panel 505 arranged on the base 100, and a signal is notified to the system control unit 501 when the button is input. In addition, various position sensors 506 arranged for detecting the stop position of each stage and outputting the position to the system control unit 501 are also arranged.

An anterior segment image of the eye E to be inspected captured by the image sensor 220 is stored in the memory 508. The pupil and corneal reflection image of the eye E is extracted from the image stored in the memory 508, and alignment detection is performed. In addition, the anterior segment image of the eye E to be inspected captured by the image sensor 220 is combined with text and graphic data and displayed on the LCD monitor 116.
The eye refractive power calculation ring image photographed by the image sensor 210 is stored in the memory 508.

  The solenoids 510 and 511 are driven and controlled by a command from the system control unit 501 via a solenoid drive circuit 509. Further, the X-axis motor 103, the Y-axis motor 104, the Z-axis motor 108, the jaw holder motor 113, and the fixation target induction motor 224 are driven by a command from the system control unit 501 via the motor drive circuit 514. .

  The measurement light source 201, the external eye illumination light sources 221 a and 221 b, and the fixation target light source 217 are controlled to be turned on / off and change in light quantity by a command from the system control unit 501 via the light source driving circuit 513.

(Flow from alignment to eye refractive power measurement)
Next, the movement of the system control unit 501 from auto alignment control to eye refractive power measurement will be described.

  The examiner operates the joystick 101 to operate the measurement unit 110 until a part of the eye pupil to be examined is displayed on the LCD 116. When a part of the pupil is displayed on the LCD 116 and the measurement start switch 504 is pressed, the system control unit 501 starts the automatic alignment control.

  The system control unit 501 analyzes the anterior segment image obtained by the image sensor 220 and detects the pupil of the eye to be examined. When the pupil is detected, motor control of the XY axes is performed by the motor drive circuit 514 in a direction in which the pupil central axis and the optical axis 01 of the measurement unit 110 coincide. When the center axis of the pupil of the eye E and the optical axis 01 of the measurement unit 110 approximately match, the reflected light 221a ′ and 221b ′ of the external eye illumination 221 appears on the anterior eye part. Motor control of each of the XYZ axes is performed so that the predetermined position and size are set. When 221a 'and 221b' reach a predetermined position and size, the above-described alignment detection bright spots Ta, Tb, and Tc appear in the pupil region.

  When the three bright spots Ta, Tb, and Tc can be detected, the system control unit 501 controls the motor drive circuit 514 to move the measurement unit 110 up and down so that the center bright spot Ta and the optical axis 01 of the measurement unit 110 coincide with each other. Drive in the left-right direction. Next, the system control unit 501 further drives the measurement unit 110 in the front-rear direction so that the bright spots Ta and Tb are aligned in the vertical direction with respect to the bright spot Tc, so that the three corneal bright spots Ta, Tb, and Tc are 1 in the vertical direction. Complete alignment in line.

  Next, in order to measure the eye refractive power, the system control unit 501 retracts the diffusing plate 222 inserted in the optical path 01 for auto-alignment from the optical path 01. The light quantity of the measurement light source 201 is adjusted, and the measurement light beam is projected onto the fundus Er of the eye E to be examined.

  Reflected light from the fundus follows the optical path 02 and is received by the image sensor 210. The captured fundus image is captured in a ring shape by the ring diaphragm 207 by the refractive power of the eye to be examined. This ring image is stored in the memory 508. Next, the barycentric coordinates of the ring image stored in the memory 508 are calculated, and an elliptic equation is obtained by a well-known method. The obtained oval diameter, minor axis, and inclination of the major axis are calculated, and the eye refractive power of the eye E is calculated. The relationship between the obtained ellipse diameter, the eye refractive power value corresponding to the minor axis, and the angle of the ellipse axis on the light receiving surface of the image sensor 210 and the astigmatism axis is corrected in advance in the device manufacturing process. .

  When the eye refractive power is obtained, the motor drive circuit 514 moves the lens 215 to a position corresponding to the refractive index of the eye E by the fixation target induction motor 224 until the position corresponding to the refractive power value. Thereafter, the lens 215 is moved away by a predetermined amount, the fixation target 216 is fogged, the measurement light source is turned on again, and the refractive power is measured.

  In this way, the true value of the eye refractive power can be obtained by repeating a series of procedures of measuring refractive power → clouding with the fixation target 216 → measurement of refractive power until the measured value becomes stable.

(Explanation of relationship between alignment state and received light flux)
Here, the relationship between the received light beam of the corneal reflected light beam and the bright spot image due to the difference in alignment state will be described. FIG. 6, FIG. 7, and FIG. 8 respectively show the cases where the X and Y directions are in the best state and the distance in the Z direction is the best, far, and close in the positional relationship between the measuring device and the eye to be examined. Yes.

  When the distance in the Z direction is the best, the received light beams La, Lb, and Lc pass through the alignment prism diaphragm 223 as parallel light beams as shown in FIG. 6A and are converged on the image sensor 220 by the lens 218. Since the light beam La passes straight through the central opening 223a of the alignment prism diaphragm, it reaches the optical axis 04 on the image sensor 220. Since the light beam Lb is refracted and transmitted through the alignment prism 301a and then transmitted through the opening 223b of the alignment prism diaphragm, the light beam Lb reaches the Y axis downward direction with an angle of view with respect to the optical axis 04 on the image sensor 220. Similarly, since the light beam Lc is refracted and transmitted through the alignment prism 301b and then transmitted through the opening 223c of the alignment prism diaphragm, the light beam Lc reaches the optical axis 04 on the image sensor 220 in the Y-axis upward direction.

  Since the LCD 116 displays the image sensor 220 from the opposite side of the lens 218, the optical positional relationship is displayed upside down and left and right, so that the bright spot image of the light beam La as shown in FIG. 6B. Ta is displayed at the center of the screen, but the bright spot image Tb of the light beam Lb is displayed at the top of the screen, and the bright spot image Tc of the light beam Lc is displayed at the bottom of the screen. As a result, since the three bright spot images are in a state in which there is no vertical alignment, it is possible to determine that the alignment in the Z direction is the best by detecting this state. The XY direction is determined by the position of the center of gravity of the central bright spot image Tb.

  On the other hand, when the distance in the Z direction is long, the received light beams La, Lb, and Lc are incident on the lens 218 as convergent light as shown in FIG. 7A, and thus converge once before the image sensor 220 and diverge. In this state, light is received. In this case, the light beam La becomes a blurred image whose center of gravity is on the optical axis 04. The light beam Lb is also a blurred image in the same manner, but receives the refracting action of the lens surface off the axis of the lens 218, so that the position of the center of gravity reaches a position shifted to the left in the X axis on the image sensor 220. The position in the Y-axis direction is the same as when the distance in the Z direction in FIG. 6 is the best.

  In this case, the LCD 116 is displayed in a state of being inclined clockwise as shown in FIG. 7B, and by detecting this inclination angle, it is possible to determine that the alignment in the Z direction is far away. Become.

  When the distance in the Z direction is short, the relationship is reversed, and the received light beams La, Lb, and Lc are incident on the lens 218 as divergent light as shown in FIG. The light is received in the state before the start. In this case, as shown in FIG. 8B, it is displayed in a state of being inclined counterclockwise, and it is possible to determine that the alignment in the Z direction is close by detecting this inclination angle. Become.

(Relationship between baseline length and lens diameter)
The tilt angles of the bright spot image arrangements as shown in FIGS. 7B and 8B depend on the distance between the centers of the left and right openings 223b of the alignment prism diaphragm 223 and the center of 223c (referred to as the base line length). . That is, if the baseline length is short, the light beams Lb and Lc pass through the paraxial region of the optical system, and thus reach the X position close to each other on the image sensor 220, but if the baseline length is long, the paraxial axis of the optical system. Since it passes through the outer region, it is strongly influenced by the spherical aberration of the lens, and reaches X positions that are separated from each other on the image sensor 220. Since the Y position is constant, the change in the detected tilt angle becomes sensitive to the change in the Z state of the alignment, and as a result, the alignment state can be determined with higher accuracy.

  On the other hand, when the base line length is increased, the light beams Lb and Lc pass through the lens 218, particularly in the vicinity of both end portions in the X direction, and thus a larger aperture is required. However, due to the downsizing of measuring devices and miniaturization of image sensors, optical arrangements with shorter focal lengths are often required, and a sufficient aperture can be secured due to shape constraints such as lens curvature and edge thickness. It can be difficult.

(Vignetting of alignment beam)
FIG. 9 shows a state in which the Z state of the alignment in FIG. 8 is close and is further decentered in the X direction. FIG. 9A shows a state in which the diameter of the lens 218 is smaller than the base line length and a part of the light beam Lc is drawn. In this state, as shown in FIG. 9 (b), the bright spot image Tc is dark and becomes below the detection threshold level and cannot be detected, and the alignment state cannot be determined normally. This means that the range in which the alignment detection in the X direction can be detected is greatly limited by the aperture of the lens and is easily limited to a narrow range.

(Aperture shape, bright spot shape, and shape discrimination detection)
FIG. 10 assumes a case where the initial alignment state is abnormal as described above, and shows a case where the alignment is shifted in a severe direction with respect to the vignetting of the light beam (the Z direction is close and the XY directions are both eccentric). The mode of correspondence in an embodiment is shown. More specifically, in FIGS. 10A and 10B, the shape of the opening of the alignment prism diaphragm 223 is compared with the shape of the bright spot image.

  In the present embodiment, as a characteristic part of the present embodiment, a plurality of openings have different shapes as shown in FIG. Specifically, the central opening 223a has a perfect circle shape, and the left and right openings 223b and 223c have an elliptical shape. In this case, as shown in FIG. 10B, the corresponding bright spot images are formed in a similar shape to the respective opening portions, and are displayed on the LCD 116. This is due to the fact that the optical image generally approaches the aperture shape in a defocused state in the imaging optical system. In other words, the aperture stop in the alignment prism stop functions as a light beam splitting unit composed of an aperture having a combination of at least two shapes in the present invention. The beam splitting means may generate a plurality of different index images from the reflected light of the eye to be examined. The plurality of alignment prisms function as light beam deflecting means for deflecting the light beams split by the light beam splitting means in different directions.

  In this state, the number of bright spot images is less than the predetermined number of three, for example, the luminous flux Lc is scattered and the bright spot image Tc is not detected, but the other two are the central bright spot image Ta and the system control unit 501. The shape with the upper bright spot image Tb can be identified and detected separately.

  This identification method can be performed by image recognition processing with a reference image corresponding to each bright spot image stored in advance in the memory unit 508 when the apparatus is manufactured and shipped. Alternatively, numerical parameters that directly define the shape, such as the aspect ratio of the outer shape, the positional relationship of the feature points, and the number of points may be used. The identification of the shape of the plurality of index images obtained from the optical system according to the present invention is executed by the module area that functions as the identification means in the system control unit 501.

  In the present embodiment, for the purpose of increasing the brightness of the bright spot image, a simple elliptical shape is assumed on the assumption that the opening area is enlarged without increasing the width in the X direction. If it is a characteristic shape, separation and detection can be similarly performed. If the central bright spot image Ta can be specified, the alignment state in the XY direction can be determined from the XY coordinates, and further, the alignment state in the Z direction can be determined from the inclination angle between the central bright spot image Ta and the upper bright spot image Tb. This determination accuracy is as high as when the number of bright spot images is a predetermined number of three, and the system control unit 501 can control the motor drive circuit 514 more reliably. If this control becomes accurate, it is not necessary to repeat the alignment operation, and a high measurement throughput can be realized.

  On the other hand, when the Z position is the best in the initial state although it is infrequent, the two bright spot images are arranged vertically and the bright spot images are focused, making it difficult to identify the shape. In this case, if the amount of deviation in the X direction is determined from the two detected bright spot images and the operation is performed in the X direction based on this, the rash is eliminated. Then, the central bright spot image Ta is identified from the three bright spot images, and the shift amount determination process including the Y direction may be performed. The above corresponds to the expansion of the range of high-precision auto alignment.

  As an opposite example, FIG. 11 shows a case where the opening shapes are the same as shown in FIG. 11A, unlike the example of FIG. In this case, as shown in FIG. 11B, the corresponding bright spot images are formed in the same shape and displayed on the screen. At this time, if the bright spot image Tc ′ is not detected, the system control unit 501 cannot distinguish between the central bright spot image Ta and the upper bright spot image Tb ′. In this state, since the central bright spot image Ta cannot be specified, at least the alignment state in the XY directions becomes a determination error. In this case, the above-described auxiliary alignment method using the pupil center and the reflected images 221a 'and 221b' of the external illumination 221 is bypassed.

  Since this process is rougher than the alignment method based on the corneal bright spot image, it is necessary to repeat the alignment detection and motor control based on the final corneal bright spot image a plurality of times, which requires more time.

(flowchart)
The flowchart shown in FIG. 12 is a processing procedure from the start to the completion of auto alignment in the present embodiment. The examiner moves the measurement unit 110 by the above-described operation, confirms the observation image of the eye E to be examined by the LCD 116, and then presses the measurement start switch 504, whereby the automatic alignment control is started.

  First, in step S100, the system control unit 501 performs a corneal bright spot image detection process, and determines whether the number of bright spot images detected in step S101 is a predetermined number of three. If the determination here is “YES”, the amount of deviation in the XYZ direction of the alignment state is determined from the positional relationship of the bright spot image in step S102. Based on the amount of deviation, a determination process is performed in step S103 as to whether or not the measurement range is set in advance. If the determination here is “YES”, the auto-alignment process is completed and the eye refractive power measurement is started. .

  If the determination in step S103 is “NO”, the process proceeds to step S104, the motor drive circuit 514 is controlled, and the measurement unit 110 is moved from the deviation amount determined in step S102 to the set alignment target position. Let After that, the processing from step S100 to S103 is performed again, and it is confirmed that it is within the measurable range, and the processing is completed.

  If “NO” in the determination process of step S101, that is, if the detected number of bright spot images is not a predetermined number of three, the process proceeds to step S300, and this time a determination process is performed to determine whether there are two less than the predetermined number. . If the determination here is “YES”, the system control unit 501 performs identification processing of the shape of each bright spot image as described above in step S301. Subsequently, in step S302, the amount of deviation in the XY direction is determined from the central bright spot image Ta identified as a perfect circle shape, and the Z direction is determined from the positional relationship with either the bright spot image Tb or Tc identified as one elliptical shape. The amount of deviation is determined. Since this determination accuracy is based on the corneal bright spot image as in the case of three, it is equivalent to the determination accuracy in step S102 described above.

  In this state, since the predetermined number of three bright spot images are not detected, it is clear that the alignment state is not appropriate. Therefore, the measurement unit 110 is directly connected in step S303 without performing the determination process of whether or not the measurement is possible. A process of moving to the alignment target position is performed. Since the alignment target position is set with high accuracy, the subsequent processing from step S100 to S103 can be performed at once, and the auto-alignment processing can be completed quickly.

  If “NO” in the determination processing in step S300, that is, if the number of detected bright spot images is one or less, auxiliary coarse alignment processing (rough alignment) shown in steps S200 to S203 is performed. First, in step S200, the pupil center is detected, then in S201, a reflection image of the external eye illumination is detected, and in step S202, the shift amount in the XYZ directions is determined from the positional relationship between the pupil center and the external eye illumination reflection image. Thereafter, the process proceeds to step S203, the measurement unit 110 is moved from the deviation amount determined in step S202 to the set alignment target position, and the process returns to step S100 again.

  If the pupil center is not detected in step S200, the examiner performs a process of manually operating the joystick 101 until the pupil center is detected in a step (not shown). In that case, there may be an operation assisting function such that the system control unit 501 determines the direction to be operated by the examiner based on the information of the anterior ocular segment image and displays it on the LCD 116 with an arrow. The determination accuracy in step S202 is less accurate than the determination method in steps S102 and S302 using the corneal reflection bright spot image described above, and as a result, the loop processing from step S100 to step S104 or from step S100 to step S203 is performed. Since this process is performed a plurality of times, it takes time to complete the auto-alignment process.

  However, the processing from step S300 to step S303, which is a feature of the present embodiment, reduces the probability of passing through rough alignment processing, and as a result, measurement throughput is maintained.

  The determination and instruction performed in the above flowchart are executed by the module area functioning as the determination unit and the instruction unit in the system control unit 501, respectively. The determining unit determines the alignment state based on the state of the index image detected by the detecting unit, and the instruction unit instructs driving by the driving unit based on the determination result by the determining unit. In the present embodiment, the index image is a plurality of index images composed of a combination of at least two shapes, and the determination unit identifies each shape of the plurality of index images or based on the difference in the identified shapes. The alignment state is determined.

  In this embodiment, the alignment state, which is one mode of the determination result by the determination unit, may be displayed on the LCD monitor 116 as the display unit. At that time, display control means for displaying in which direction of the XYZ the optical system should be moved to the extent by using a display form such as an arrow or a schematic diagram may be arranged in the system control unit 501. By adding this configuration, alignment can be suitably performed by manual alignment, for example.

  For example, when trying to expand the range in which high-precision auto-alignment is possible in the conventional configuration, it is conceivable to use a large-diameter light receiving lens as an alternative to widen the detection range of reflected light. However, such a correspondence leads to an increase in size and cost of the device, which is inconvenient as a device configuration.

  Here, in one of the conventional ophthalmologic apparatuses, in order to enable wide-range and high-precision auto-alignment, a light beam is irradiated to the eye cornea from a direction different from the optical axis direction and the optical axis, and the reflected image automatically Alignment is performed. Specifically, an auto alignment unit with coarse accuracy is separately provided as a supplement to the narrow detection range. However, in this case, at least a two-step alignment process of coarse adjustment and fine adjustment is required. Therefore, when the fixation of the eye to be examined is not stable, or conversely, the measurable position range of the apparatus is strictly set, there is a problem that the tracking process for the eye to be examined is not in time and measurement takes time. As described above, according to the present embodiment, it is possible to suitably obtain the alignment state without such time.

  Further, in the conventional example such as the example of FIG. 11, when the shape of the alignment prism diaphragm 223 is the same and there is no processing from step S300 to step S303, the amount of deviation of the corneal bright spot image is reduced. Since the determination possible range is narrow and the rough alignment process is passed with a high probability, it takes time to complete the entire process. This greatly affects the deterioration of measurement throughput when the initial alignment state is greatly decentered or when the subject's fixation state is unstable. Further, when the examiner manually operates an operation means such as a joystick, it is necessary to perform rough alignment so that the eye to be examined is in the detection range in the initial state, that is, the range in which the reflected light can be detected. Such operation by the examiner's manual has been troublesome for the examiner.

  Therefore, in the present embodiment, at least two index images (its shape, intensity, etc.) among a plurality of index images obtained from the reflected light from the eye to be examined are identified, and the identified index image (its shape, intensity, etc.) is identified. ), The alignment state between the optical system of the ophthalmologic apparatus and the eye to be examined is determined. With this configuration, the detection range of the alignment is increased, and the situation where manual operation in the conventional apparatus is required is reduced.

(Other embodiments)
In the above embodiment, the left and right openings of the alignment prism diaphragm 223 have the same shape. In addition, even when a minimum number of bright spot images are detected due to a combination of factors such as light shielding by eyelashes or a disease on the corneal surface, each bright spot image may be identified. In addition, although the maximum number of bright spot images is three, the number of bright spot images is not limited to this, and may be appropriately designed according to the measuring apparatus so that each can be identified. Although an example of an eye refractive power measurement device has been described here, the present invention is not limited to this as long as it is an ophthalmologic device that performs auto-alignment processing by detection processing of a cornea reflection image. For example, a tonometer, a fundus camera device, OCT (Optical Coherence Tomography), SLO (Scanning Laser Ophthalmoscope) and the like are also included. In addition, although a corneal reflection image is used, it is also possible to adopt an aspect in which alignment is performed by reflected light from other parts of the eye to be examined. Furthermore, some conventional ophthalmic apparatus alignment methods have a configuration having a plurality of dedicated alignment light sources and light-receiving units. By identifying this, the same effect as in the present embodiment can be obtained.

  That is, as the above-described light projecting means, a plurality of alignment light sources composed of a combination of at least two light emitting portion shapes may be provided. That is, the same effect as that of the present embodiment can also be obtained by arranging the alignment light source from a plurality of light emitting units having different shapes capable of irradiating a plurality of different index images to the eye to be examined.

  Furthermore, it is also possible to execute the above-described alignment by, for example, making the brightness of the plurality of index images different, not the difference in shape of the plurality of index images. In this case, the intensity of at least two index images, so-called pixel values, may be configured to be different. Specifically, the light source corresponding to the index image is configured to have different light emission amounts, or a filter or the like is disposed in any of the alignment diaphragms so that the light beam passes with a different light amount from the other diaphragms. It may be configured.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. The processing to be executed also constitutes one aspect of the present invention.

100 Stage 110 Measurement unit 223 Alignment prism diaphragm 301 Alignment prism 501 System controller

Claims (18)

An optical system for irradiating the eye to be examined and receiving reflected light from the eye to be examined;
Identifying means for identifying at least two index images among a plurality of index images obtained by the optical system from the reflected light;
Determination means for determining an alignment state between the optical system and the eye to be examined based on the difference between the identified index images;
An ophthalmologic apparatus comprising:   The ophthalmologic apparatus according to claim 1, wherein the identification unit identifies a shape of the index image.   The ophthalmologic apparatus according to claim 1, wherein the optical system further includes a light beam splitting unit that is disposed in an optical path of the reflected light and generates a plurality of different index images from the reflected light.   The ophthalmologic apparatus according to claim 1, wherein the optical system includes an alignment light source including a plurality of light emitting units having different shapes capable of irradiating a plurality of different index images to the eye to be examined.   The determination unit determines, based on the shape of the index image, whether the obtained index image corresponds to the predetermined number of index images when a predetermined number of the plurality of index images cannot be obtained. The ophthalmologic apparatus according to any one of claims 1 to 4, wherein the alignment state between the optical system and the eye to be examined is determined based on the obtained index image.   The determining means determines the number of detected index images by the detecting means, and if the detected number is less than a predetermined number, the shape of the detected index image is identified to identify each index. The ophthalmologic apparatus according to claim 1, wherein an alignment state is determined by specifying an image.   The ophthalmologic apparatus according to claim 1, further comprising an instruction unit that instructs driving by the driving unit based on a determination result by the determining unit.   The ophthalmologic apparatus according to any one of claims 1 to 7, further comprising a display control unit that causes a display unit to display a display form indicating a determination result by the determination unit.   A program that causes a computer to be executed as each unit of the ophthalmologic apparatus according to any one of claims 1 to 8. From the optical system, irradiate the subject's eye with light, and receive the reflected light of the light from the subject's eye,
Identifying at least two index images among a plurality of index images obtained from the reflected light;
A method for controlling an ophthalmologic apparatus, comprising: determining an alignment state between the optical system and the eye to be examined based on a difference between the identified index images.   The method of controlling an ophthalmologic apparatus according to claim 10, wherein the index image is identified by identifying a shape of the index image.   The ophthalmic apparatus according to claim 10 or 11, wherein the index image is generated by a light beam splitting unit that is arranged in an optical path of the reflected light and generates a plurality of different index images from the reflected light. Control method.   The method of controlling an ophthalmologic apparatus according to claim 10, wherein the index image is irradiated to the eye to be examined from an alignment light source including a plurality of light emitting units having different shapes.   In determining the alignment state, when a predetermined number of the plurality of index images cannot be obtained, the index image obtained based on the shape of the identified index image corresponds to any of the predetermined number of index images. The ophthalmologic according to claim 10, wherein the alignment state between the optical system and the eye to be examined is determined based on the corresponding index image obtained. Device control method.   In determining the alignment state, the number of detected index images is determined. If the detected number is less than a predetermined number, the shape of each detected index image is identified to identify each index image. The method for controlling an ophthalmologic apparatus according to any one of claims 10 to 14, wherein the alignment state is identified and determined.   The method for controlling an ophthalmologic apparatus according to claim 10, further comprising a step of instructing driving of the optical system based on a determination result of the alignment state.   The method for controlling an ophthalmologic apparatus according to any one of claims 10 to 16, further comprising a display control step of causing a display unit to display a display form indicating the determination result of the alignment state.   A program for causing a computer to execute each step of the method for controlling an ophthalmologic apparatus according to any one of claims 10 to 17.

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