ophthalmic devices

Abstract

To provide an ophthalmic device that can move the measurement unit to the focused position with greater precision and in a shorter amount of time. [Solution] The ophthalmic device 1 includes a measuring unit 10 having a distance measuring light source 11 that emits distance measuring light, a light receiving sensor 12 that receives the distance measuring light reflected by the cornea of ​​the eye under examination, and an image acquisition unit 13 that acquires an image of the eye under examination; a moving mechanism 20 that moves the measuring unit 10; a distance acquisition unit 31 that acquires the distance to the eye under examination in response to the reception of the distance measuring light; a focus evaluation value acquisition unit 32 that acquires a focus evaluation value using the captured image; and a processing unit 33 that, if the distance has been acquired by the distance acquisition unit 31, uses that distance to move the measuring unit 10 to the focus position, and if the distance has not been acquired by the distance acquisition unit 31, uses the focus evaluation value to move the measuring unit 10 toward the focus position.

Description

[Technical Field]

[0001] The present invention relates to an ophthalmologic apparatus that moves a measurement unit to an in-focus position. [Background Art]

[0002] In conventional ophthalmologic apparatuses, in order to perform accurate measurement of an eye to be examined, alignment has been performed by moving the measurement unit relative to the eye to be examined. In particular, alignment in the depth direction has been performed such that the measurement unit is brought into an in-focus state with respect to a measurement site of the eye to be examined.

[0003] As for methods for specifying an in-focus position, which is the position in the depth direction at which the measurement unit is brought into an in-focus state with respect to the eye to be examined, there are, for example, a method of measuring a distance related to the eye to be examined, and a method using a focus evaluation value of a captured image of the eye to be examined (see, for example, Patent Document 1). [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2015-221090 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] While methods for measuring distance to the eye under examination can pinpoint the focal point with high accuracy, they have a narrow depth range for distance measurement. This means that if the measurement unit is located far from the focal point, it cannot measure the distance and therefore cannot pinpoint the focal point. When distance cannot be measured, the measurement unit must be moved in the depth direction as needed to enable measurement. However, moving it too quickly could cause the unit to move beyond the measurement range, so it must be moved slowly. Thus, when moving the measurement unit slowly without knowing whether the focal point is in front of or behind the examiner, the time it takes to enable measurement becomes long.

[0006] Another approach involves using an autofocus method based on focus evaluation values ​​to move the measurement unit to the in-focus position. In this case, compared to the distance measurement method, focus evaluation values ​​can be acquired over a wider range in the depth direction, allowing the measurement unit to move to the in-focus position. However, this method has the problem of lower accuracy in identifying the in-focus position compared to the distance measurement method. Furthermore, the autofocus method requires the measurement unit to move in the direction that increases the focus evaluation value. Therefore, if the in-focus position is lost, it is necessary to determine which direction to move the measurement unit to increase the focus evaluation value, resulting in poor tracking of the subject's eye. To solve these problems, it is conceivable to use equipment that can perform imaging, calculations, and movement in a short time, while also acquiring more accurate focus evaluation values. However, using such equipment would increase costs.

[0007] The present invention has been made in response to the above circumstances and aims to provide an ophthalmic device that can move the measurement unit to the focused position in a shorter time and with higher precision. [Means for solving the problem]

[0008] To achieve the above objective, an ophthalmic apparatus according to one aspect of the present invention comprises: a measuring unit having a distance measuring light source that emits distance measuring light to the eye under examination, a light receiving sensor that receives the distance measuring light reflected by the cornea of ​​the eye under examination, and an image acquisition unit that photographs the eye under examination and acquires an image; a moving mechanism for moving the measuring unit; a distance acquisition unit that acquires the distance to the eye under examination in response to the reception of distance measuring light by the light receiving sensor; a focus evaluation value acquisition unit that acquires a focus evaluation value using the image acquired by the image acquisition unit; and a processing unit that, when the distance has been acquired by the distance acquisition unit, performs processing to move the measuring unit to the focus position using the acquired distance, and when the distance has not been acquired by the distance acquisition unit, performs processing to move the measuring unit toward the focus position using the focus evaluation value.

[0009] With this configuration, even if the distance to the eye under examination cannot be obtained, the direction of the focal point can be identified by using the focus evaluation value, and the measurement unit can be moved toward the focal point. Furthermore, when the measurement unit approaches the focal point unit, the accuracy of moving the measurement unit to the focal point can be improved by using the distance acquisition result to the eye under examination. In this way, the measurement unit can be moved to the focal point with greater accuracy and in a shorter amount of time.

[0010] Furthermore, in an ophthalmic apparatus according to one aspect of the present invention, the moving mechanism has a driving means for moving the measuring unit, and the processing unit may control the driving means to move the measuring unit to the focus position.

[0011] This configuration allows the measurement unit to be automatically moved to the focus position.

[0012] Furthermore, in an ophthalmic device according to one aspect of the present invention, the processing unit may output information regarding the focus position.

[0013] With this configuration, even when the measurement unit is automatically moved to the focus position, information such as the distance to the focus position can be output to the examiner or other personnel.

[0014] Furthermore, in an ophthalmic device according to one aspect of the present invention, the moving mechanism may be operated manually by an operator, and the processing unit may output information regarding the focus position to the operator in order to move the measuring unit to the focus position.

[0015] This configuration allows the measuring unit to be moved to the focus position even when it is operated manually. [Effects of the Invention]

[0016] According to one aspect of the present invention, the ophthalmic device can move the measuring unit to the focused position in a shorter time and with higher precision. [Brief explanation of the drawing]

[0017] [Figure 1] Block diagram showing the configuration of an ophthalmic device according to an embodiment of the present invention. [Figure 2] A schematic diagram showing the configuration of the optical system of the measurement unit in the same embodiment. [Figure 3] A diagram illustrating the movement of the measurement unit using the focus evaluation value in the same embodiment. [Figure 4] Flowchart showing the operation of the ophthalmic device according to this embodiment. [Figure 5] This figure shows an example of the change in focus evaluation value with respect to the Z-axis position of the measurement unit in the same embodiment and an example of the captured image. [Modes for carrying out the invention]

[0018] Hereinafter, the ophthalmologic apparatus according to the present invention will be described with reference to embodiments. In the following embodiments, constituent elements and steps denoted by the same reference numerals are identical or corresponding, and repeated description thereof may be omitted. The ophthalmologic apparatus according to the present embodiment is configured to move a measurement unit toward an in-focus position using a focus evaluation value when a distance related to an eye to be examined cannot be acquired, and move the measurement unit to the in-focus position using the acquired result when the distance related to the eye to be examined becomes acquirable.

[0019] FIG. 1 is a block diagram showing the configuration of an ophthalmologic apparatus 1 according to the present embodiment, and FIG. 2 is a schematic diagram showing an example of the configuration of an optical system included in a measurement unit 10. The ophthalmologic apparatus 1 performs predetermined measurement on an eye 2 to be examined. The measurement on the eye 2 to be examined may be, for example, measurement of the refractive power, corneal curvature radius, or the like of the eye 2 to be examined. The ophthalmologic apparatus 1 may be, for example, a refracto-keratometer, or may be another ophthalmologic apparatus.

[0020] The ophthalmologic apparatus 1 according to the present embodiment includes a measurement unit 10 that performs measurement on an eye 2 to be examined, a moving mechanism 20 that moves the measurement unit 10, a distance acquisition unit 31 that acquires a distance related to the eye 2 to be examined, a focus evaluation value acquisition unit 32 that acquires a focus evaluation value, and a processing unit 33 that performs processing for moving the measurement unit 10 to an in-focus position using the distance related to the eye 2 to be examined and the focus evaluation value, and may further include a monitor 34 and a storage unit 35 as necessary. The measurement unit 10 has an optical system mechanism for performing various types of measurement on the eye 2 to be examined, and includes, for example, a distance measurement light source 11, a light receiving sensor 12, and an image acquisition unit 13. As shown in Fig. 2, the measurement unit 10 may further include a half mirror 14, a mirror 15, and a sensor 16 used for measurement such as refractive power of the eye 2 to be examined, as necessary. In Fig. 2, illustrations of components other than distance measurement light, such as light sources, lenses, diaphragms, filters, masks, and visual targets, are omitted. The configuration of the optical system shown in Fig. 2 is an example, and the measurement unit 10 may have an optical system configuration different from that shown in Fig. 2. The moving mechanism 20 may include, for example, a driving means 21. In the present embodiment, the direction in which the measurement unit 10 approaches or moves away from the eye 2 to be examined, that is, the left-right direction in Fig. 2, is defined as the Z-axis direction, and the directions perpendicular to the Z-axis direction are defined as the X-axis direction and the Y-axis direction.

[0021] The distance measurement light source 11 emits distance measurement light to the eye 2 to be examined. The light receiving sensor 12 receives the distance measurement light reflected by the cornea of the eye 2 to be examined. The light receiving sensor 12 may be, for example, a line sensor. When alignment between the eye 2 to be examined and the measurement unit 10 in the Z-axis direction is achieved, that is, when the measurement unit 10 is located at the in-focus position in the Z-axis direction, the light receiving position of the reflected light on the light receiving sensor 12 may be designed to be a predetermined position. The predetermined position may be, for example, the center of the light receiving sensor 12 that is a line sensor. The light receiving position of the reflected light on the light receiving sensor 12 may be, for example, the brightest position on the light receiving sensor 12.

[0022] The image acquisition unit 13 photographs the eye under examination 2 and acquires the captured image. As shown in Figure 2, the image acquisition unit 13 may acquire the captured image of the eye under examination 2 via, for example, a half mirror 14 and a mirror 15. The image acquisition unit 13 may also be an image sensor such as a CCD or CMOS.

[0023] The moving mechanism 20 moves the measuring unit 10. The moving mechanism 20 may, for example, move the measuring unit 10 relative to the base of the ophthalmic device 1. The moving mechanism 20 may, for example, move the measuring unit 10 in at least the Z-axis direction relative to the base. In this embodiment, the case in which the moving mechanism 20 moves the measuring unit 10 in the XYZ three-axis directions relative to the base will be mainly described. The moving mechanism 20 may or may not have a driving means 21 such as a motor for moving the measuring unit 10. In the latter case, the measuring unit 10 may be moved by an operator manually operating the moving mechanism 20. In this embodiment, the case in which the moving mechanism 20 has a driving means 21 for moving the measuring unit 10 will be mainly described, and the case in which it does not have will be described later. The driving means 21 may, for example, move the measuring unit 10 in at least the Z-axis direction. The driving means 21 may, for example, move the measuring unit 10 in the XYZ three-axis directions.

[0024] The distance acquisition unit 31 acquires the distance to the eye under examination 2 in response to the reception of distance-measuring light by the light-receiving sensor 12. Preferably, the distance acquired by the distance acquisition unit 31 can specify the distance between the in-focus position, which is the Z-axis position of the measurement unit 10 when it is in focus with respect to the eye under examination 2, and the current position of the measurement unit 10 in the Z-axis direction. For example, when the measurement unit 10 is in the in-focus position, if the light-receiving position of the reflected light on the light-receiving sensor 12 is a predetermined position, the distance acquisition unit 31 may acquire that the distance in the Z-axis direction from the current position of the measurement unit 10 to the in-focus position is 0 when the light-receiving position on the light-receiving sensor 12 that received the reflected light is the predetermined position, and acquire the distance in the Z-axis direction from the current position of the measurement unit 10 to the in-focus position according to the difference between the light-receiving position of the reflected light on the light-receiving sensor 12 and the predetermined position. Thus, the distance to the eye under examination 2 acquired by the distance acquisition unit 31 may be, for example, a distance with the in-focus position as the reference position. It goes without saying that, for example, the distance acquisition unit 31 may acquire a distance with a reference position other than the focus position. Even in this case, it is preferable that the positional relationship between the reference position other than the focus position and the focus position is predetermined. The distance acquisition unit 31 can only acquire distance when the measurement unit 10 is within a predetermined range in the Z-axis direction. If the measurement unit 10 is not within the predetermined range in the Z-axis direction, for example, the reflected light of the distance measuring light cannot be received by the light receiving sensor 12.

[0025] The focus evaluation value acquisition unit 32 acquires a focus evaluation value using the captured image acquired by the image acquisition unit 13. The focus evaluation value is, for example, a value that indicates the evaluation result of the focus state. For example, the focus evaluation value may be the contrast value of the image, or it may be any other value used to control autofocus. For example, the focus evaluation value may be a value that increases as it approaches the focus position, or a value that decreases as it approaches the focus position. In this embodiment, the former case will be mainly described. Furthermore, the focus evaluation value acquisition unit 32 may, for example, acquire the focus evaluation value of the entire captured image, or acquire the focus evaluation value of a specific region of the captured image. In the latter case, the focus evaluation value acquisition unit 32 may, for example, identify a predetermined region such as the corneal surface using template matching, image segmentation, or other methods, and acquire the focus evaluation value for that identified region. Furthermore, in the ophthalmic device 1 according to this embodiment, as will be described later, it is only necessary to determine which direction to move the measurement unit 10 using the focus evaluation value. Therefore, it is not necessarily required to use expensive equipment for acquiring the focus evaluation value, and conventional general-purpose equipment can be used.

[0026] If the distance has been acquired by the distance acquisition unit 31, the processing unit 33 performs a process to move the measuring unit 10 to the focus position using the acquired distance. If the distance has not been acquired by the distance acquisition unit 31, the processing unit 33 performs a process to move the measuring unit 10 toward the focus position using the focus evaluation value acquired by the focus evaluation value acquisition unit 32. In this embodiment, the case in which the processing unit 33 controls the driving means 21 to move the measuring unit 10 to the focus position will be mainly described, and the case in which it does not is described later.

[0027] When the distance acquisition unit 31 acquires a distance, the distance from the current position of the measuring unit 10 in the Z-axis direction to the focus position can be determined. Therefore, the processing unit 33 may control the driving means 21 of the moving mechanism 20 so that the measuring unit 10 moves in the Z-axis direction by that distance. For example, when the distance acquisition unit 31 acquires the distance from the current position of the measuring unit 10 to the focus position, the processing unit 33 moves the measuring unit 10 in the Z-axis direction by the acquired distance, thereby moving the measuring unit 10 to the focus position.

[0028] On the other hand, if the distance has not been acquired by the distance acquisition unit 31, the measurement unit 10 will be moved toward the focus position using the focus evaluation value. However, with only one focus evaluation value, it is not possible to determine which side the focus position is on, that is, whether the focus position is on the positive or negative side of the Z-axis direction from the current position of the measurement unit 10. Therefore, the processing unit 33 may first control the driving means 21 of the moving mechanism 20 to move the measurement unit 10 in a predetermined direction, and then use the focus evaluation value acquired before the move and the focus evaluation value acquired after the move to determine the direction in which the focus position exists. In other words, the direction in which the focus position exists relative to the current Z-axis position of the measurement unit 10 may be determined using focus evaluation values ​​acquired at two or more different positions in the Z-axis direction. In this way, by determining the direction in which the focus position exists using the focus evaluation value, the measurement unit 10 can be moved toward the focus position in a unique direction, eliminating the need to search for the focus position by trial and error, and allowing the measurement unit 10 to be moved to the focus position in a shorter time.

[0029] FIG. 3 is a diagram for explaining movement control of the measurement unit 10 using two focus evaluation values. First, assume that the focus evaluation value obtained using a captured image captured when the measurement unit 10 is located at position Z1 in the Z-axis direction is F1. Thereafter, assume that the processing unit 33 controls the driving means 21 to move the measurement unit 10 by a predetermined distance in a predetermined direction, so that the measurement unit 10 comes to be located at position Z2 in the Z-axis direction. Then, assume that the focus evaluation value obtained using a captured image captured at that position is F2. For example, in a case where the closer the in-focus position, the larger the focus evaluation value, if F1>F2, position Z1 is closer to the in-focus position than position Z2, and if F1<F2, position Z2 is closer to the in-focus position than position Z1. Therefore, for example, when F1>F2, the processing unit 33 may move the measurement unit 10 by a predetermined distance in the direction from position Z2 toward position Z1, that is, the right direction in FIG. 3, and when F1<F2, may move the measurement unit 10 by a predetermined distance in the direction from position Z1 toward position Z2, that is, the left direction in FIG. 3. Further, as an example, after moving the measurement unit 10, a focus evaluation value may be acquired at the position after the movement, and the same movement control may be performed. In this way, the processing unit 33 can move the measurement unit 10 in a direction approaching the in-focus position using the focus evaluation value. Note that, when the distance has not been acquired, it is preferable that a single movement distance of the measurement unit 10 in the Z-axis direction is smaller than the length of the range in the Z-axis direction in which distance measurement is possible. This is to prevent the measurement unit 10 from exceeding the distance-measurable range when the measurement unit 10 is moved using the focus evaluation value.

[0030] Although the measurement unit 10 can be moved toward the in-focus position using the focus evaluation value, the measurement unit 10 cannot be positioned at the in-focus position with high accuracy. On the other hand, when the measurement unit 10 approaches the in-focus position, the distance can be acquired by the distance acquisition unit 31. Therefore, after the distance is acquired, by moving the measurement unit 10 using the acquired distance, the measurement unit 10 can be moved to the in-focus position with high accuracy.

[0031] The predetermined direction in which the measurement unit 10 is moved to obtain the second focus evaluation value may be, for example, a predetermined direction (e.g., the positive direction of the Z axis, or the opposite direction), or it may be a direction determined according to the position of the measurement unit 10 at that time. In the latter case, for example, the predetermined direction may be the direction from the current position of the measurement unit 10 toward the midpoint of the movement range of the measurement unit 10 in the Z axis direction. Furthermore, it is preferable that the distance traveled when moving the measurement unit 10 to obtain the second focus evaluation value is smaller than the length of the range in the Z axis direction that can be measured.

[0032] In this explanation, we have described the process for performing alignment in the Z-axis direction using the distance acquired by the distance acquisition unit 31 and the focus evaluation value acquired by the focus evaluation value acquisition unit 32. However, the processing unit 33 may also perform alignment in the X-axis and Y-axis directions using the same methods as in the conventional method.

[0033] Furthermore, the processing unit 33 may output information regarding the focus position, for example. This output may be, for example, displayed on the monitor 34, or it may be other output such as audio output. For example, if the distance has not been acquired by the distance acquisition unit 31, the information regarding the focus position may include information indicating the direction in which the focus position exists relative to the current position of the measurement unit 10 in the Z-axis direction. If the distance has been acquired by the distance acquisition unit 31, the information regarding the focus position may include information indicating the distance to the focus position along with its direction. By outputting this information, for example, the examiner can learn about the direction of movement of the measurement unit 10 and the distance the measurement unit 10 has moved.

[0034] The monitor 34 may, for example, display information regarding the focus position output by the processing unit 33. The monitor 34 may also display, for example, the captured image or measurement results related to the eye under examination 2. The monitor 34 may be, for example, a liquid crystal display or an organic EL display.

[0035] The storage unit 35 may store, for example, distances acquired by the distance acquisition unit 31 and focus evaluation values ​​acquired by the focus evaluation value acquisition unit 32. Other information and setting values ​​may also be stored in the storage unit 35. The storage unit 35 is preferably implemented using a volatile recording medium, but may also be implemented using a non-volatile recording medium. The recording medium may be, for example, a semiconductor memory or a magnetic disk.

[0036] Furthermore, the ophthalmic device 1 may further include an acquisition unit that acquires information such as refractive power related to the eye under examination 2 based on information acquired by the sensor 16. Alternatively, the acquisition of information such as refractive power related to the eye under examination 2 may be performed using captured images acquired by the image acquisition unit 13. In this case, the measurement unit 10 does not need to have the sensor 16. Also, although Figure 1 shows a case where the measurement unit 10, which is moved by the moving mechanism 20, includes only a distance measuring light source 11, a light receiving sensor 12, and an image acquisition unit 13, it goes without saying that the measurement unit 10 may also include any one or more components from, for example, a distance acquisition unit 31, a focus evaluation value acquisition unit 32, a processing unit 33, a monitor 34, and a storage unit 35.

[0037] Next, the operation of the ophthalmic device 1 will be explained using the flowchart in Figure 4. In the flowchart in Figure 4, a larger focus evaluation value indicates that the measurement unit 10 is closer to the focus position.

[0038] (Step S101) The measuring light source 11 emits distance measuring light. The light receiving sensor 12 acquires the result of light reception in response to the emission of distance measuring light. If the measuring unit 10 is within the range in which distance can be measured using distance measuring light, the light receiving sensor 12 will receive the distance measuring light reflected from the cornea of ​​the eye under examination 2. The distance acquisition unit 31 acquires the distance according to the result of light reception acquired by the light receiving sensor 12. On the other hand, if the measuring unit 10 is not within the range in which distance can be measured using distance measuring light, the distance acquisition unit 31 will not acquire the distance.

[0039] (Step S102) If the distance was obtained in step S101, proceed to step S103; otherwise, proceed to step S106.

[0040] (Step S103) The processing unit 33 stores the distance acquired by the distance acquisition unit 31 in the storage unit 35.

[0041] (Step S104) The processing unit 33 outputs information regarding the focus position to the monitor 34 according to the acquired distance. The monitor 34 then displays the information regarding the focus position.

[0042] (Step S105) The processing unit 33 moves the measuring unit 10 to the focus position by controlling the driving means 21 of the moving mechanism 20 using the distance acquired by the distance acquisition unit 31. Once this movement is complete, the series of processes for moving the measuring unit 10 to the focus position is finished.

[0043] (Step S106) The image acquisition unit 13 photographs the eye 2 under examination and acquires the captured image. This captured image may be stored on a recording medium or the like (not shown).

[0044] (Step S107) The focus evaluation value acquisition unit 32 acquires a focus evaluation value using the captured image acquired in step S106.

[0045] (Step S108) The processing unit 33 determines whether a previous focus evaluation value, i.e., an old focus evaluation value, is stored in the storage unit 35. If an old focus evaluation value is stored, the process proceeds to step S111; otherwise, the process proceeds to step S109.

[0046] (Step S109) The processing unit 33 stores the focus evaluation value obtained in step S107 in the storage unit 35.

[0047] (Step S110) The processing unit 33 moves the measuring unit 10 in a predetermined direction by controlling the driving means 21 of the moving mechanism 20. Then, the process returns to step S106.

[0048] (Step S111) The processing unit 33 determines whether the new focus evaluation value, i.e., the latest focus evaluation value acquired in step S107, is greater than the old focus evaluation value, i.e., the focus evaluation value stored in the storage unit 35. If the new focus evaluation value is greater than the old focus evaluation value, the process proceeds to step S112; otherwise, the process proceeds to step S113. Preferably, the old focus evaluation value is the focus evaluation value acquired immediately before the latest focus evaluation value.

[0049] (Step S112) The processing unit 33 moves the measuring unit 10 in the same direction as the latest movement direction by controlling the driving means 21 of the moving mechanism 20.

[0050] (Step S113) The processing unit 33 controls the drive means 21 of the moving mechanism 20 to move the measuring unit 10 in the opposite direction to the latest movement direction.

[0051] The distance traveled by the measurement unit 10 in steps S112 and S113 may be determined independently in advance. For example, the distance traveled by the measurement unit 10 in step S113 may be greater than the distance traveled by the measurement unit in step S112. The movement of the measurement unit 10 may be performed continuously at a predetermined speed, and during this movement, processes such as capturing images, acquiring focus evaluation values, comparing two focus evaluation values, and acquiring distances may be performed in parallel. In this case as well, it is preferable that the measurement unit 10 does not move beyond the length of the range in the Z-axis direction in which distance measurement is possible between the time it is performed to acquire the distance and the time it is performed to acquire the next distance.

[0052] (Step S114) The processing unit 33 stores the new focus evaluation value in the storage unit 35. Preferably, this storage is performed in such a way that the latest focus evaluation value stored in the storage unit 35 can be identified. For example, the focus evaluation value may be stored in the storage unit 35 by overwriting. Then, the process returns to step S101.

[0053] Note that the flowchart in Figure 4 does not include the processing of measuring refractive power, corneal curvature radius, etc., for the eye under examination 2. However, after the series of processes in the flowchart in Figure 4 are completed, that is, after the process in step S105 is performed, processing for measuring the eye under examination 2 may be performed. Also, in the flowchart in Figure 4, the case in which the relationship between the latest focus evaluation value and the previously acquired focus evaluation value is compared each time when the distance is not acquired by the distance acquisition unit 31 is described, but this is not required. Normally, in movement control using focus evaluation values, it is considered that the direction of movement of the measurement unit 10 does not change when the third or subsequent focus evaluation values ​​are acquired. For example, after the direction of movement is determined using the focus evaluation values ​​acquired the first and second times, if the answer in step S102 is NO, the acquisition of the captured image and the acquisition of the focus evaluation value may not be performed, and only the process of moving the measurement unit 10 by a predetermined distance in the same direction as before may be performed. Furthermore, the order of processing in the flowchart in Figure 4 is just an example, and the order of each step may be changed if similar results can be obtained.

[0054] Furthermore, the ophthalmic device 1 may have a control unit that causes each component to sequentially execute the processing of each step. The control unit then controls the sequence of each process, so that each component can execute the processes shown in the flowchart of Figure 4, for example.

[0055] Next, the operation of the ophthalmic device 1 according to this embodiment will be explained using a specific example. First, once the subject fixes their face to the face rest and the position of the subject's face is established, the examiner inputs an instruction to the ophthalmic device 1 to start measurement. This instruction is received by the processing unit 33, which then passes an instruction to the distance acquisition unit 31 to acquire the distance to the eye 2 being examined. Upon receiving this instruction, the distance acquisition unit 31 emits distance-measuring light from the distance-measuring light source 11 and causes the light-receiving sensor 12 to acquire the result of the light reception. Then, the distance acquisition unit 31 acquires the distance to the eye 2 being examined using the result of the light reception (step S101). In this case, the distance acquisition unit 31 is unable to acquire the distance and passes a message to the processing unit 33 indicating that the distance could not be acquired (step S102).

[0056] Upon receiving a message indicating that distance could not be obtained, the processing unit 33 instructs the focus evaluation value acquisition unit 32 to acquire the focus evaluation value. Upon receiving this instruction, the focus evaluation value acquisition unit 32 instructs the image acquisition unit 13 to acquire an image of the eye under examination 2, uses that image to acquire the focus evaluation value, and passes it to the processing unit 33 (steps S106, S107). Since this is the first acquisition of the focus evaluation value, the processing unit 33 stores the focus evaluation value in the storage unit 35 and controls the driving means 21 of the moving mechanism 20 to move the measurement unit 10 in a predetermined direction (steps S108~S110).

[0057] Subsequently, the processing unit 33 again instructs the focus evaluation value acquisition unit 32 to acquire the focus evaluation value. Upon receiving this instruction, the focus evaluation value acquisition unit 32 causes the image acquisition unit 13 to acquire the captured image, uses that captured image to acquire the focus evaluation value, and passes it to the processing unit 33 (steps S106, S107). At this point, the old focus evaluation value is stored in the storage unit 35, so the processing unit 33 reads the old focus evaluation value from the storage unit 35 and determines whether the new focus evaluation value is greater than the old focus evaluation value (steps S108, S111). In this case, it is assumed that the new focus evaluation value is greater than the old focus evaluation value. Then, the processing unit 33 controls the driving means 21 of the moving mechanism 20 to move the measurement unit 10 in the same direction as the latest movement (step S112). If the new focus evaluation value is greater than the old focus evaluation value, the processing unit 33 will move the measurement unit 10 in the opposite direction to the latest movement (step S113). Furthermore, the processing unit 33 overwrites and stores the latest focus evaluation value in the storage unit 35 (step S114).

[0058] Next, the processing unit 33 sends an instruction to the distance acquisition unit 31 to acquire the distance again. In response to this instruction, distance measuring light is emitted from the distance measuring light source 11, the light receiving sensor 12 acquires the result of the light reception, and the distance acquisition unit 31 acquires the distance using the result of the light reception (step S101). In this case, let's assume that the distance still could not be acquired (step S102). Then, the movement of the measurement unit 10 using the focus evaluation value is repeated until the distance can be acquired (steps S106~S108, S111, S112, S114).

[0059] Then, when the distance between the measurement unit 10 and the eye under examination 2 falls within the range for distance acquisition, the distance-measuring light emitted from the distance-measuring light source 11 is reflected by the eye under examination 2, and the reflected distance-measuring light is received by the light-receiving sensor 12. The distance related to the eye under examination 2 is then acquired by the distance acquisition unit 31 using the result of this light acquisition and passed to the processing unit 33 (step S101). This acquired distance is assumed to be the distance in the Z-axis direction from the current position of the measurement unit 10 to the focus position.

[0060] When the processing unit 33 receives the acquired distance, it stores that distance in the storage unit 35 and uses that distance to output information regarding the focus position to the monitor 34 (steps S102 to S104). The information regarding the focus position may also indicate the direction in which the focus position is located relative to the current position of the measurement unit 10 in the Z-axis direction, and the distance to the focus position. By outputting this information, the examiner can know in which direction and by how much the measurement unit 10 will move.

[0061] Subsequently, the processing unit 33 moves the measurement unit 10 to the focus position by controlling the driving means 21 of the moving mechanism 20 using the acquired distance (step S105). Specifically, the measurement unit 10 is moved by the acquired distance. After this, for example, the eye under examination 2 may be photographed by the sensor 16 and the captured image may be acquired, and the refractive power of the eye under examination 2 may be acquired and output using the captured image.

[0062] Figure 5 shows the relationship between the distance in the Z-axis direction from the reference position of the measurement unit 10 and the focus evaluation value obtained using the captured image taken by the image acquisition unit 13 of the measurement unit 10. In Figure 5, the reference position is defined as the in-focus position. That is, the position where the value on the horizontal axis is "0" is the in-focus position. For reference, captured images of the eye under examination 2 taken when the measurement unit 10 is located at several distances from the reference position are shown below. Referring to these captured images, it can be seen that the contrast value of the captured image increases as it approaches the in-focus position, indicating that it is approaching the in-focus state. In the example in Figure 5, it is assumed that distance acquisition for the eye under examination 2 using the rangefinder is possible in the range of -4 mm to +2 mm from the in-focus position.

[0063] For example, if the initial position of the measurement unit 10 is -20 mm from the focus position, distance acquisition using the rangefinder light cannot be performed at that position. Therefore, the measurement unit 10 will be moved towards the focus position using the focus evaluation value. When the distance from the focus position to the measurement unit 10 becomes -4 mm or more through this movement control using the focus evaluation value, distance acquisition using the rangefinder light becomes possible, and the focus position is identified. Then, the measurement unit 10 will be moved to that identified focus position.

[0064] As described above, with the ophthalmic device 1 according to this embodiment, even when the distance to the eye under examination 2 cannot be obtained, the focus evaluation value can be used to identify which side of the measurement unit 10 is in focus over a wider range, and the measurement unit 10 can be moved toward the in-focus position. In this way, since the direction of the in-focus position can be identified using the focus evaluation value and the measurement unit 10 can be moved in that direction, the time required to move the measurement unit 10 to the in-focus position can be shortened compared to the case where the direction of the in-focus position cannot be identified relative to the current position of the measurement unit 10. Furthermore, when the measurement unit 10 approaches the in-focus unit, the accuracy of moving the measurement unit 10 to the in-focus position can be improved by using the measurement result of the distance to the eye under examination 2. Thus, with the ophthalmic device 1 according to this embodiment, the measurement unit 10 can be moved to the in-focus position in a shorter time with higher accuracy.

[0065] Furthermore, in the ophthalmic device 1 according to this embodiment, for example, even if the subject moves or closes their eyelids and loses focus while the measuring unit 10 is within the range of distance measurement, the focus can be easily identified by subsequently obtaining the distance to the subject eye 2 using the range measuring light, and the measuring unit 10 can be moved to the focus position. Therefore, high tracking performance for the subject eye 2 can be achieved without necessarily using expensive equipment.

[0066] Furthermore, in conventional ophthalmic devices, focus evaluation values ​​are usually acquired for a predetermined area of ​​the eye being examined, making it impossible to acquire focus evaluation values ​​when the patient's eyelids are closed. On the other hand, in the ophthalmic device 1 according to this embodiment, the focus evaluation value is used only to determine the direction of movement of the measurement unit 10. For example, the measurement unit 10 can be moved in the direction approaching the in-focus position using the focus evaluation value acquired when the patient's eyelids are closed. Then, by moving the measurement unit 10 to the in-focus position based on the distance acquired using the rangefinder after the eyelids are opened, highly accurate positioning in the Z-axis direction can be achieved.

[0067] Furthermore, since the moving mechanism 20 has a drive means 21, the processing unit 33 controls the drive means 21 to move the measuring unit 10, thereby automatically moving the measuring unit 10 to the focus position, reducing the burden on operators such as examiners. In addition, by outputting information regarding the focus position, information regarding the focus position can be notified to examiners even when the measuring unit 10 is automatically moved to the focus position.

[0068] In this embodiment, the case in which the moving mechanism 20 has a driving means 21 and the measuring unit 10 is automatically moved to the focus position has been mainly described, but this is not required. The moving mechanism 20 does not have to have a driving means 21. In this case, the moving mechanism 20 may be operated manually by an operator, such as an examiner. That is, the measuring unit 10 may be moved manually by the manual operation of the moving mechanism 20. In this case, the processing unit 33 may output information regarding the focus position to the operator in order to move the measuring unit 10 to the focus position. That is, the processing of this output may be a process to move the measuring unit 10 to the focus position, or a process to move the measuring unit 10 toward the focus position. This output may be, for example, a display on the monitor 34, or it may be other output such as an audio output. When the distance to the eye under examination 2 is acquired by the distance acquisition unit 31, information indicating, for example, in which direction and by how much the measuring unit 10 should be moved to reach the focus position may be output. Furthermore, if the distance to the eye under examination 2 has not been acquired by the distance acquisition unit 31, the direction for moving the measurement unit 10 to the focus position, which is determined using, for example, the focus evaluation value, may be output. For example, in step S105 of the flowchart in Figure 4, the operator may manually move the measurement unit 10 based on the outputted information until the distance to the focus position becomes 0. Therefore, when the movement mechanism 20 is operated manually, the process of acquiring the distance and the process of outputting information regarding the focus position may be repeated until the measurement unit 10 moves to the focus position. Also, for example, in steps S110, S112, and S113, the operator may manually move the measurement unit 10 according to the outputted direction based on the outputted information. In this way, even when the measurement unit 10 is moved manually, the measurement unit 10 can be moved to the focus position.

[0069] Furthermore, in the above embodiment, each process or function may be implemented by centralized processing by a single device or a single system, or by distributed processing by multiple devices or multiple systems.

[0070] Furthermore, in the above embodiment, the exchange of information between each component may, for example, be performed by outputting information from one component and receiving information from the other component if the two components performing the information exchange are physically different, or by moving from the processing phase corresponding to one component to the processing phase corresponding to the other component if the two components performing the information exchange are physically the same.

[0071] Furthermore, in the above embodiment, each component may be configured with dedicated hardware, or, if it is a component that can be implemented by software, it may be implemented by executing a program. For example, each component can be implemented by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory. During execution, the program execution unit may execute the program while accessing the storage unit or recording medium.

[0072] Furthermore, the embodiments described above are illustrative examples for specifically carrying out the present invention and do not limit the technical scope of the present invention. The technical scope of the present invention is indicated by the claims rather than by the description of the embodiments, and modifications within the literal scope and equivalent meaning of the claims are intended. [Explanation of Symbols]

[0073] 1 Ophthalmology equipment 10 measuring units 11 Light source for distance measurement 12 Light receiving sensor 13 Image acquisition unit 20 Moving mechanism 21 Driving means 31 Distance acquisition part 32 Focus evaluation value acquisition unit 33 Processing Unit

Claims

1. A rangefinder light source that emits rangefinder light into the eye being examined. A light receiving sensor that receives distance measuring light reflected from the cornea of ​​the eye being examined, and A measurement unit having an image acquisition unit that photographs the eye under examination and acquires an image, A moving mechanism for moving the aforementioned measuring unit, A distance acquisition unit acquires the distance to the eye being examined in response to the reception of distance measurement light by the light receiving sensor, A focus evaluation value acquisition unit acquires a focus evaluation value using the captured image acquired by the image acquisition unit, An ophthalmic apparatus comprising: a processing unit that, when a distance is acquired by the distance acquisition unit, performs a process to move the measurement unit to the focus position using the acquired distance; and, when a distance is not acquired by the distance acquisition unit, performs a process to move the measurement unit toward the focus position using the focus evaluation value.

2. The moving mechanism has a driving means for moving the measuring unit, The ophthalmic apparatus according to claim 1, wherein the processing unit controls the driving means to move the measuring unit to the focus position.

3. The ophthalmic apparatus according to claim 2, wherein the processing unit further outputs information regarding the focus position.

4. The aforementioned moving mechanism is operated manually by an operator. The ophthalmic apparatus according to claim 1, wherein the processing unit outputs information regarding the focusing position to the operator in order to move the measuring unit to the focusing position.

Images