System and method for measuring shape of lens surface

Abstract

The present invention provides a shape measuring system and a shape measuring method for measuring the shape of a lens surface of an optical lens, such as a lens for eyewear, an objective / eyepiece lens of a telescope, or a lens of a magnifier. [Solution] A measuring system for measuring the shapes of the front and back lens surfaces of a lens 11, wherein: while the lens 11 is held by a rotating holder 12 and rotated in the circumferential direction, detection light is applied from a distance sensor 15 to a lens surface which is being measured, and distance is measured on the basis of reflected light from the lens surface; the distance sensor 15 is held by a sensor rotating mechanism 13; the distance sensor 15 is moved while the distance to the lens surface is maintained in a direction transverse to the lens surface; and the attitude of a holding mechanism is controlled such that the detection light is applied to the lens surface from the normal direction as the distance sensor 15 moves.

Description

Lens surface shape measurement system and shape measurement method

[0001] The present invention relates to a shape measurement system and a shape measurement method for measuring the shape of the lens surface of an optical lens such as an eyeglass lens, an objective or eyepiece lens of a telescope, or a lens of a magnifying glass.

[0002] Displacement sensors have traditionally been used to measure the shape of objects without contact. Displacement sensors measure the amount of movement of an object when it moves from one position to another. However, because they measure the distance to the object and calculate the amount of displacement, they are also used to measure the shape of the object itself. That is, they are also used as distance sensors to measure the distance to the object and dimension measuring instruments to measure the dimensions of the object. Measurement methods using displacement sensors include optical, eddy current, ultrasonic, and laser focus methods, and the optimal measurement method is selected based on the properties of the object to be measured, measurement accuracy, etc. When measuring the shape of a lens, optical or laser focus methods are suitable because lenses are made of transparent materials such as glass or plastic. Patent Document 1 shows an example of a technology for acquiring shape data using a laser focus displacement sensor.

[0003] JP 2018-86754 A

[0004] However, when optical or laser focus displacement sensors (i.e., distance sensors) irradiate a lens with detection light, specular reflection and scattered light are not always obtained from transparent objects with curved surfaces like lenses, often resulting in missing or inaccurate distance information, making it difficult to obtain accurate shape data. Specifically, specular reflection can only be received from a curved surface in a direction normal to or close to the normal, and while scattered light can theoretically be received regardless of angle, the amount of light is reduced, making measurement difficult in many cases. Furthermore, despite the difficulty of obtaining accurate shape data, accurate shape data of the lens is necessary for accurate analysis of lens characteristics. Therefore, a technology for accurately obtaining lens shape data using existing displacement sensors was needed.

[0005] To solve the above problem, in a first aspect, a measurement system for measuring the surface shape of at least one of the front and rear surfaces of a lens includes a rotation mechanism that holds the lens and rotates it in a circumferential direction, a distance sensor that irradiates the lens surface to be measured with detection light and measures distance based on the reflected light of the detection light from the lens surface, a holding mechanism that holds the distance sensor, and an attitude control mechanism that moves the distance sensor in a direction transverse to the lens surface while maintaining a distance from the lens surface and controls the attitude of the holding mechanism as the distance sensor moves so that the detection light is irradiated from the lens surface to be measured from a direction normal to or near the normal. This allows the distance sensor to move along the curve of the lens surface while maintaining the distance from the lens and irradiating the lens surface with detection light from a direction normal to or near the normal. Therefore, the shape of a curved lens surface can be accurately measured using the distance sensor. Furthermore, because the lens rotates in a circumferential direction, the lens surface can be scanned widely by moving the distance sensor and rotating the lens to acquire distance data. Such a shape measurement system can accurately measure the lens surface shape of lenses that are difficult to measure using existing distance sensors.

[0006] The term "lens" includes all transparent lenses with curved surfaces on either or both sides that converge or diverge light rays, such as those used in eyeglasses, telescopes, binoculars, and magnifying glasses. Spectacle lenses include not only spherical lenses but also aspherical lenses and progressive-power lenses. In this context, a "rotation mechanism" refers to a mechanism that rotates a lens using a drive device capable of controlling the rotational position, such as a servo motor or step motor. A "distance sensor" refers to a sensor that measures the distance to an object (in this context, a transparent lens). Distance sensors can be optical or laser-focus types that irradiate a detection light beam and capture the reflected light. Examples of suitable distance sensors include those that calculate distance from the phase shift of reflected light, those that create a pinhole at the receiving position to restrict the optical path and calculate distance from the wavelength of light focused within the pinhole, and those that use optical elements such as photodiodes, CCD (Charge Coupled Device) sensors, and CMOS (Complementary Metal Oxide Semiconductor) sensors. Specifically, confocal, PSD (position sensitive detector), and image sensor types are preferred. It is also preferable that the reflected light is specularly reflected without diffusing. A single distance sensor may be used for the lens, or two may be used to measure the lens surface from both the front and back. Because the distance sensor is configured to rotate the lens, even if the distance sensor itself moves along a simple linear trajectory, it can scan all directions of the lens surface. The distance sensor, held by the holding mechanism, is controlled by the attitude control mechanism so that the detection light is emitted from a direction normal to or near the normal to the lens surface being measured. In this invention, the normal direction or a direction near the normal direction does not necessarily have to strictly coincide with the normal of a curved surface. This is because distance data can be obtained as long as the reflected light is reflected approximately toward the direction of the exit (i.e., the light receiving port). Therefore, the normal direction or a direction near the normal direction is defined as any direction that is recognized as a normal direction for the purposes of the invention.The posture control mechanism may be, for example, a posture control mechanism using an articulated robot with a combination of multiple axes, or may be configured with a structure that simply moves linearly along the lens curve.

[0007] In addition, in means 2, the attitude control mechanism includes a first drive unit equipped with the holding mechanism and linearly moving the distance sensor forward and backward, a second drive unit equipped with a swivel mechanism and linearly moving the swivel mechanism, the first drive unit is mounted on the swivel mechanism, the direction of movement of the distance sensor and the direction of movement of the swivel mechanism are arranged parallel to each other, the swivel mechanism is moved forward and backward to change the distance from the center of rotation of the swivel mechanism to the distance sensor, thereby adjusting the swivel radius of the swivel mechanism, and the swivel mechanism is controlled with the adjusted swivel radius to rotate the distance sensor along a curve corresponding to the curvature of the lens surface, and the distance sensor is moved in a direction opposite to the movement direction of the swivel mechanism by an amount equal to or approximately the amount of movement of the swivel mechanism when moving forward and backward, thereby maintaining the distance between the lens arranged in a fixed position and the distance sensor. This is an example of an attitude control mechanism and is configured to suitably acquire distance data by the distance sensor from a normal direction or a direction close to the normal direction of the lens surface. This allows the distance sensor to scan the lens surface by simply moving across it in a straight line. The rotation mechanism is driven by a second drive unit. The farther away from the rotation center of the rotation mechanism, the larger the rotation radius and the gentler the curve. Conversely, the closer to the rotation center, the sharper the curve. The "rotation mechanism" rotates the first drive unit around the rotation center of the rotation mechanism using a drive unit capable of controlling the rotation position, such as a servo motor or step motor. The rotation may be, for example, not just in the same direction, but also by a reciprocating motion that oscillates. When rotating the distance sensor, a distance must be maintained so that the sensor does not come into contact with the lens surface. This distance can be easily calculated using the adjusted rotation radius, the coordinates of the lens surface, and the coordinates of the distance sensor, and a simulation to avoid contact is easily performed. However, as long as a certain distance is maintained between the lens surface and the distance sensor, the numerical value does not need to be so precise. The "first drive unit" and "second drive unit" can be, for example, an electric actuator capable of controlling the position. The "swivel mechanism" may be, for example, a disk-like frame attached to the rotating shaft of a controllable motor equipped with a speed reducer mechanism.

[0008] In addition, in means 3, the distance sensor moves across the lens surface between the center and the outer periphery. This minimizes the amount of movement of the distance sensor, allowing the entire lens surface to be scanned. It is preferable for the distance sensor to move linearly when crossing. In means 4, the distance sensors are disposed on both sides of the lens, facing the front and back lens surfaces, respectively, so that the lens surface shapes on the front and back sides of the lens are measured simultaneously by different distance sensors. This allows simultaneous measurement of both the front and back sides of the lens, reducing measurement errors and enabling more accurate acquisition of the lens shape. In means 5, a calculation means is provided for calculating the shape of the lens surface based on distance data at multiple points on the lens surface obtained by scanning the rotating lens and the distance sensor moving across the lens surface relative to the rotating lens. The shape of the lens surface can be obtained by calculation using the calculation means of means 5 based on the distance data acquired by the above means. For example, the calculation means may perform calculations using the same calculation means of a computer device as any of means 1 to 4, or the distance data obtained by any of means 1 to 4 may be calculated using the calculation means of another computer device. When it says "based on distance data," the shape of the lens surface may be identified using only the acquired distance data, or the shape of the lens surface may be identified by performing an interpolation calculation on the area between distance data based on the distance data.

[0009] In addition, in means 6, the rotation mechanism includes a rotating unit that rotates together with the lens and a holding unit that holds the rotating unit, one or more second distance sensors are disposed on the holding unit side so as to be able to measure the distance to a target on the rotating unit side, and when the measured distance changes with the rotation of the rotating unit, the distance data of the lens surface is corrected based on the amount of change measured by the second distance sensor. In means 7, the rotation mechanism includes a rotating unit that rotates together with the lens and a holding unit that holds the rotating unit, one or more second distance sensors are disposed on the rotating unit side so as to be able to measure the distance to a target on the holding unit side, and when the measured distance changes with the rotation of the rotating unit, the distance data of the lens surface is corrected based on the amount of change measured by the second distance sensor. In this way, rotational runout caused by rotating the lens in the circumferential direction is detected (measured) as a change in the distance between the rotating unit and the holding unit, and when the distance changes, rotational runout has occurred, so the distance data of the lens surface can be corrected based on the amount of change, enabling accurate measurement of the lens surface shape. The difference between means 6 and 7 is whether the second distance sensor is disposed in the holding part or the rotating part. This is particularly effective when, for example, in a system in which the rotating part is rotated by meshing gears, the rotating part may be subjected to vibrations or tilts that cause it to wobble up and down due to various factors such as gear vibration, gear backlash, or processing errors. The "second distance sensor" may be a specific sensor similar to the "distance sensor" described above, but it is preferable to use, for example, an electrostatic sensor or a confocal sensor in order to detect slight changes in the distance between the rotating part and the holding part. The distance (gap) between the rotating part and the holding part may be approximately 0.1 to 1 mm, and preferably approximately 0.5 mm.

[0010] The theory behind detecting changes in the distance (spacing) between the rotating unit and the holding unit using multiple second distance sensors is as follows: If there is rotational runout when the rotating unit rotates, the distance from the holding unit may not be constant depending on the phase. Therefore, the amount of change in distance is obtained as, for example, an inclination angle with respect to the holding unit, and coordinate transformation based on that angle, for example, using a rotation vector or a rotation matrix, can be performed to move the sensor to a position where there is no rotational runout. Furthermore, if there are three or more second distance sensors, the position of each sensor is determined based on three-dimensional coordinates, and the plane on which the second distance sensor exists is determined based on those coordinates. Therefore, calculation can be performed by coordinate transformation, for example, using a rotation vector or a rotation matrix, based on how the plane on which the second distance sensor exists intersects with the direction of the plane of the rotating unit that is perpendicular to the rotation axis.

[0011] In addition, in means 8, two second distance sensors are positioned 180 degrees apart across the center of rotation of the lens, and the amount of change in distance is obtained based on the difference in measurement values ​​of the two second distance sensors. This makes it easy to obtain the tilt parameter. In means 9, the distance sensor is moved along a line segment connecting the two second distance sensors, crossing between the center and outer periphery of the lens surface. If two second distance sensors are positioned in such a way, the difference in measurement values ​​can be used as the tilt parameter of the measurement direction, eliminating the need to correct for the tilt in the movement direction of the distance sensors and facilitating calculation of the correction value. In means 10, the target surface of the second distance sensor is a ring-shaped flat surface arranged along the outer periphery of the lens. When the target surface is such a ring-shaped flat surface, it is easier to maintain a constant distance between the second distance sensor and the target when rotating, making it easier to calculate the correction value.

[0012] Further, means 11 is a method for measuring the lens surface shape of at least one of the front and rear surfaces of a lens, using a distance sensor that irradiates a measurement target with detection light and measures the distance to the measurement target based on the light reflected from the lens surface. The distance sensor is positioned so that the detection light is irradiated from a normal direction or a direction close to the normal direction relative to the lens surface. In this position, the distance sensor scans the lens surface to obtain distance data at multiple points on the lens surface, and the shape of the lens surface is calculated based on the obtained distance data. This allows the distance sensor to move along the curve of the lens surface while maintaining the distance from the lens, thereby enabling the lens surface shape of a curved lens to be accurately measured using the distance sensor. The lens surface can then be scanned widely to obtain distance data and calculate the lens surface shape. Such a shape measurement system allows accurate measurement of the lens surface shape of lenses that are difficult to measure using existing distance sensors. Unlike means 1, in means 11, the lens does not necessarily need to rotate. For example, a multi-axis robot equipped with a distance sensor may be used to scan the lens surface. The meaning of the normal direction or a direction close to the normal direction is the same as above. Furthermore, for the three-dimensional data of the multiple distance data obtained by the distance sensor, it is preferable to project the two-dimensional data onto a plane intersecting the lens surface with the optical axis, particularly a plane perpendicular to the optical axis, and convert it into a planar distance from the optical axis, for example, a position specified on an x-y plane coordinate system. Furthermore, in means 12, the lens rotates in a circumferential direction, and the distance sensor is controlled to rotate along the curve of the lens surface in a direction intersecting the lens while the detection light is irradiated from a direction normal to the lens surface or a direction close to the normal direction. By rotating the lens and rotating the distance sensor in this manner, the entire lens surface can be scanned efficiently. Furthermore, in means 13, the distance sensor is controlled so as not to interfere with the lens surface when rotating.This is because if the distance sensor interferes with the lens surface when it is rotated relative to the lens surface, it will hinder the acquisition of distance data. Therefore, it is necessary to set the turning radius so that the distance sensor does not interfere with the lens surface. Specifically, when setting the turning radius of the distance sensor, for example, it is best to adjust the position of the distance sensor and the position of the lens so that the distance sensor is outside the position where the normal to the locus of the turning radius circle intersects with the lens surface.

[0013] In addition, in means 14, the distance sensors are arranged at positions facing the front and back lens surfaces of the lens, respectively, across the lens, and the lens surface shapes of the front and back lens surfaces are measured simultaneously by different distance sensors. This allows simultaneous measurement of both the front and back lens surfaces, reducing measurement errors and enabling more accurate acquisition of the lens shape. In means 15, the detection light emitted from the distance sensor is coherent light. Using coherent light as the detection light enables more accurate detection. Examples of coherent light include laser light and maser light. In means 16, the lens is controlled to rotate in a circumferential direction and stop once every predetermined rotation angle, and the distance sensor is controlled to move in a diameter direction of the lens surface while facing the lens surface and when the lens stops, the distance data at multiple points is acquired as the sensor moves. This claims a specific and efficient lens scanning method. The lens is stopped at a predetermined phase position and the distance sensor is moved in the radial direction of the lens to scan. By operating the lens and distance sensor in this manner, the entire lens surface can be scanned evenly and in a balanced manner to acquire distance data. Furthermore, in means 17, the distance sensor is controlled to move in the radial direction of the lens while facing the lens surface and stop at any of a plurality of stop positions, and the lens is controlled to rotate at each stop position of the distance sensor to acquire a plurality of distance data. This also claims a specific and efficient lens scanning method. By operating the lens and distance sensor in this manner, the lens surface is scanned concentrically by the distance sensor, which stops at a predetermined radial position of the lens by rotating the lens, and the entire lens surface can be scanned evenly and in a balanced manner to acquire distance data.

[0014] In addition, in means 18, a rotational shake of a rotating part that rotates together with the lens is measured by a second distance sensor from the side of a holding part that holds the rotating part to the rotating part as a target, and if the measured distance changes with the rotation of the rotating part, the amount of change is used as a correction value to correct the distance data and calculate the shape of the lens surface. In addition, in means 19, a rotational shake of a rotating part that rotates together with the lens is measured by a second distance sensor disposed on the side of the rotating part to the side of the holding part that holds the rotating part as a target, and if the measured distance changes with the rotation of the rotating part, the amount of change is used as a correction value to correct the distance data and calculate the shape of the lens surface. In this way, if rotational shake occurs when the lens is rotated in the circumferential direction, the rotational shake is detected (measured) as a change in the distance between the rotating part and the holding part, and if the distance changes, rotational shake has occurred, so the distance data of the lens surface can be corrected based on the amount of change, enabling accurate measurement of the lens surface shape. The difference between means 18 and means 9 is whether the second distance sensor is disposed in the holding part or the rotating part. This is particularly effective when, for example, the rotating part is rotated by meshing gears, and various factors such as bearing runout, gear vibration, gear backlash, and processing errors can cause the rotating part to vibrate or tilt up and down.

[0015] In addition, in means 20, two second distance sensors are disposed at positions 180 degrees apart across the center of rotation of the lens, and the amount of change in distance is obtained based on the difference in measurement values ​​of the two second distance sensors. This makes it possible to easily obtain the tilt parameter. In means 21, the distance sensor is moved along a line segment connecting the two second distance sensors, crossing between the center and outer periphery of the lens surface. If the two second distance sensors are located in such positions, the difference in measurement values ​​can be used as the tilt parameter of the measurement direction, eliminating the need to correct for the tilt in the movement direction of the distance sensors and making it easy to calculate the correction value.

[0016] The inventions described in each of the above means can be combined in any way. For example, it is possible to combine all or part of the configuration of the invention described in means 1 with at least part of the configuration of at least one invention from means 2 onwards. In particular, it is preferable to combine the invention described in means 1 with at least part of the configuration of at least one invention from means 2 onwards. Furthermore, any configuration may be extracted from the inventions described in means 1 to means 21 and combined with the extracted configurations. The applicant of the present application intends to obtain rights to inventions including these configurations.

[0017] According to the present invention, it is possible to accurately measure the lens surface shape of a lens that is difficult to measure using an existing distance sensor.

[0018] Schematic diagrams illustrating an overview of the main parts of a lens shape measurement system according to a first embodiment of the present invention. (a) is a schematic diagram illustrating a state in which the sub-actuator relative to the main actuator in the lens shape measurement system according to the first embodiment is at a reference position, and (b) is a schematic diagram illustrating the sub-actuator in the middle of pivoting relative to the main actuator. (a) is a schematic diagram illustrating a main part of a sensor pivoting mechanism when the turning radius of the distance sensor is small, and (b) is a schematic diagram illustrating a main part of a sensor pivoting mechanism when the turning radius of the distance sensor is large. An explanatory diagram illustrating the geometric positional relationship when the position of the lens rear surface detected by the distance sensor is projected onto a plane coordinate system according to the first embodiment. An explanatory diagram illustrating the geometric positional relationship when the position of the lens rear surface detected by the distance sensor is projected onto a plane coordinate system according to the first embodiment. A schematic diagram illustrating the position of the lens on an x-y plane coordinate system in terms of distance and angle. A block diagram illustrating the electrical configuration according to the first embodiment. A schematic diagram illustrating an overview of the main parts of a lens shape measurement system according to a second embodiment of the present invention, including two electrostatic sensors. A partially cutaway end view illustrating the specific configuration of a lens rotation mechanism according to a third embodiment of the present invention. FIG. 1 is a plan view of the lens rotation mechanism according to the same embodiment 3. FIG. 2 is a block diagram illustrating the electrical configuration according to embodiment 3. FIG. 3 is an explanatory diagram illustrating the geometric position change of the lens as viewed from a direction perpendicular to the rotation direction when the measurement position is subjected to coordinate conversion based on the angle obtained by the electrostatic sensor according to the embodiment. FIG. 4 is a schematic diagram illustrating a method for calculating the amount of deviation from the horizon based on the rotational shake of two electrostatic sensors.

[0019] Embodiments of the present invention will now be described with reference to the drawings. (Embodiment 1) FIGS. 1 and 2 are schematic diagrams outlining the essential components of a lens shape measurement system according to this embodiment. The lens shape measurement system includes a rotating holder 12 that accommodates an eyeglass lens 11 to be measured, and a sensor rotation mechanism 13. Components not directly related to the present invention will not be described. First, the rotating holder 12 will be described. The rotating holder 12 is rotatably mounted on a table; however, the table is not shown in this embodiment, as the purpose of this embodiment is to provide an overview of the essential components. The eyeglass lens 11 has lens surfaces 11A and 11B disposed so that its optical axis extends perpendicular to the rotating holder 12 (i.e., the lens surfaces 11A and 11B are disposed vertically). The eyeglass lens 11 is fixed within the rotating holder 12 by being pressed from the periphery toward the center by a jig so as not to interfere with measurement. The eyeglass lens 11 to be measured in Embodiment 1 is a meniscus-shaped lens with a circular outer periphery, known as a round lens, which has a disc-shaped outer shape and is therefore called a round lens. The rotating holder 12 is housed in a ring gear (not shown) and is rotatably arranged on a table together with the ring gear. The center of rotation of the rotating holder 12 coincides with the center of the rotating holder 12, i.e., the geometric center of the eyeglass lens 11. A pinion (not shown), also arranged on the table, is engaged with the ring gear, and a first motor device 14 is connected to the pinion. Driven by the first motor device 14, the rotating holder 12 is rotated via the pinion and gear, and the eyeglass lens 11 is rotated circumferentially together with the rotating holder 12. A first rotary encoder 10 is provided adjacent to the rotating holder 12, which detects the rotational position of the rotating holder 12, i.e., the phase of the eyeglass lens 11. The rotating holder 12, ring gear, pinion, first motor device 14, table, etc. constitute a lens rotation mechanism.

[0020] Next, the sensor rotation mechanism 13 will be described. The sensor rotation mechanism 13 is disposed adjacent to the rotating holder 12. The sensor rotation mechanism 13 is equipped with a distance sensor 15, and the sensor rotation mechanism 13 displaces the position of the distance sensor 15 relative to the rotating lens surfaces 11A and 11B, thereby scanning the lens surfaces 11A and 11B of the eyeglass lens 11 and acquiring distance data. The distance sensor 15 in this embodiment uses a confocal sensor that uses a multi-lens optical system to irradiate white light (polychromatic light) from an emission port to form an image point on the target surface (lens surface). The sensor rotation mechanism 13 includes a main actuator 17 and a sub-actuator 19 supported by the main actuator 17 via a swivel table 18. The main actuator 17 is an electric actuator and includes a slide table 21 that is driven by a built-in second motor device 20 and slides linearly in the longitudinal direction. The sub-actuator 19 is also an electric actuator and includes a slide table 23 that is driven by a built-in third motor device 22 and slides linearly in the longitudinal direction. Both the main actuator 17 and the sub-actuator 19 include a threaded rod (not shown) that converts the rotational force of the motor into a linear force, and the slide table 21 (23) is moved by the rotation of the threaded rod. Semi-closed loop control is also performed, in which the angles of the motor shafts of the motor devices 20 and 22 are detected by built-in encoders. The swivel table 18, located between the main actuator 17 and the sub-actuator 18, includes a fourth motor device 24 on which the swivel table 18 is rotatably supported. The fourth motor device 24 is fixed on the slide table 21 of the main actuator 17 and rotates the swivel table 18 on the slide table 21. A second rotary encoder 28 is also provided on the swivel table 18, which detects the rotational position of the swivel table 18, i.e., the phase of the distance sensor 15 relative to the eyeglass lens 11. The side surface of the turntable 18 is fixed to the rear surface of the sub-actuator 19, so that when the turntable 18 rotates, the sub-actuator 19 rotates together with the turntable 18.A sensor holder 25 is fixed to the slide table 23 of the sub-actuator 19. The sensor holder 25 has a pair of arms 26, and a distance sensor 15 is attached to each arm 26. The pair of distance sensors 15 are arranged so that their white light emission ports face each other. The distance sensors 15 are arranged above and below the eyeglass lens 11 held by the rotating holder 12, with the eyeglass lens 11 sandwiched between them while maintaining a distance from the eyeglass lens 11. As shown in Figure 1, the shape measurement system includes a computer device 29. The computer device 29 includes a monitor device 30, a keyboard 31 as input means, and a mouse 32 as input means.

[0021] In this configuration, the sensor rotation mechanism 13 is arranged so that the advancement and retreat directions of the slide table 21 of the main actuator 17 and the slide table 23 of the sub-actuator 19 are parallel, as shown in Fig. 1. Therefore, for example, when the slide table 21 of the main actuator 17 and the slide table 23 of the sub-actuator 19 move by equal amounts in opposite directions, the rotary holder 12 does not move and remains in a fixed position. As shown in Fig. 2(a), the rotation reference position of the sensor rotation mechanism 13 is set to a state in which the longitudinal directions of the housings of the main actuator 17 and the sub-actuator 19, which are arranged adjacent to the eyeglass lens 11 with its optical axis aligned vertically, are aligned vertically. At this rotation reference position, the center of the emission port of the distance sensor 15 is aligned with the geometric center of the eyeglass lens 11. At this position, the emission direction of white light from the distance sensor 15 coincides with the optical axis direction. When the swivel table 18 rotates from the state shown in Figure 2(a), the distance sensor 15 rotates together with the sub-actuator 19 so that the emission direction of the white light is directed in a substantially normal direction, as shown in Figure 2(b). In other words, the distance sensor 15 rotates in synchronization with the phase change of the swivel table 18, moving while tracing a curve along the lens surfaces 11A and 11B of the eyeglass lens 11. At this time, the curvature of the curve changes depending on the turning radius of the sensor holder 25. The turning radius is based on the center O of the swivel table 18 (i.e., the position of the rotation axis of the fourth motor device 24), and the longer the turning radius, the gentler the curve. If the reference for the circular locus of the turning radius from the center O is the midpoint between the pair of distance sensors 15, the turning radius r1 is short in Figure 3(a), so the curve traced by the locus of the distance sensor 15 is steep. 3(b), the slide table 23 of the sub-actuator 19 has moved upward and away from the center O of the swivel table 18, so the turning radius R2 in this case is longer than the turning radius R1, and the curve of the trajectory of the distance sensor 15 is gentler. As the slide table 23 of the sub-actuator 19 moves upward, the slide table 21 of the main actuator 17 moves an equal amount in the opposite direction, so there is no apparent change in the position of the distance sensor 15 relative to the eyeglass lens 11.

[0022] Next, the electrical configuration of the computer device 29 will be described with reference to the block diagram of Fig. 7. Note that components not directly related to the present invention will be omitted. The controller MC of the computer device 29 is connected to the distance sensor 15, the first to fourth motor devices 14, 20, 22, 24, the first and second rotary encoders 10, 28, the monitor device 30, the keyboard 31, the mouse 32, etc. via interfaces not shown. The controller MC, which serves as control means and calculation means, is composed of a known CPU, memories such as ROM and RAM, a timer, etc. The ROM in the controller MC stores a data acquisition program that causes the distance sensor 15 to acquire distance data at predetermined timing and stores the acquired distance data, a position control program for controlling the amount and direction of advancement of the slide tables 21 and 23 of the main actuator 17 and the sub-actuator 19, a position control program for controlling the position from the rotation speed of the swivel table 18 and the amount of phase change when it rotates, a position control program for rotating the rotating holder 12 and controlling the position from the amount of phase change when it rotates, a calculation program for calculating the turning radius based on input lens curve data and calculating the amount of advancement of the slide tables 21 and 23 based on the calculated turning radius, an operation program for controlling the operation timing of the rotation of the distance sensor 15 due to the rotation of the rotating holder 12 and the rotation of the swivel table 18, a calculation program for calculating to convert the distance data on the lens surfaces 11A and 11B into planar coordinates of the lens, shape data of the eyeglass lens 11 (lens size, base curve curvature, curve value, etc.), etc. The RAM in the controller MC temporarily stores the distance data acquired by the distance sensor 15 and the coordinate data converted into planar coordinates, etc.

[0023] Next, we will explain the specific control method for measuring the shape of the lens surface using this system, executed by the controller MC. In this embodiment, two methods (MODE 1 and MODE 2) are provided as examples, differing in the rotation timing of the rotating holder 12 and the rotation timing of the distance sensor 15. First, we will explain MODE 1. A. Inputting Values ​​According to the Lens Curve The operator inputs the base curve value of the lens to be measured on the screen of the monitor device 30 using the keyboard 31 or mouse 32. In this embodiment, the base curve value is determined by measuring the curvature near the apex of the lens in advance and using this value as the base curve curvature. The controller MC calculates the turning radius of the distance sensor 15 according to the base curve value. The trajectory of the turning radius circle is set from the center of the turning table 18 (turning center O) to the midpoint between the pair of distance sensors 15, and the third motor device 22 is driven according to the specified turning radius. Note that the normal direction does not need to be a strict angle as long as the reflected light can reach the internal light receiving unit from the exit port. In other words, when the distance sensor 15 rotates, the direction in which the detection light is emitted needs only to be roughly normal to the lens surface, and the allowable angular deviation from the normal direction is not uniform depending on the distance sensor 15, as it depends on the diameter of the emission outlet and the distance to the light receiving unit.

[0024] B. Operation of the Rotating Holder and Distance Sensor In MODE 1, the controller MC executes the following control. 1. The controller MC controls the first motor device 14 to rotate the rotating holder 12 clockwise, stopping it at a predetermined phase position. The stopping position of the rotating holder 12 is calculated based on the detection signal of the first rotary encoder 10, which serves as a rotation sensor. In this embodiment 1, as an example, a 360-degree rotation is divided into 30-degree step angles, and a total of 12 measurement point positions are set. Because the rotating holder 12 and the eyeglass lens 11 serving as the workpiece are concentric, the eyeglass lens 11 stops while rotating in 30-degree steps. A certain rotation reference position of the eyeglass lens 11 is set to 0 degrees (point 1). 2. While the distance sensor 15 makes one reciprocating motion in point 1, the controller MC controls the rotating holder 12 to stop at points 1 to 12. 2. Meanwhile, the controller MC controls the fourth motor device 24 to rotate the rotating table 18, causing the distance sensor 15 mounted on the sub-actuator 19 to rotate along with the eyeglass lens 11. In the first embodiment, the distance sensor 15 is initially positioned at the rotation reference position, i.e., the geometric center of the eyeglass lens 11. In MODE 1, the controller MC controls the distance sensor 15 to move to an edge position of the eyeglass lens 11 in order to scan the distance sensor 15 across the diameter of the eyeglass lens 11. The rotation phase movement of the distance sensor 15 is synchronized with the rotation phase movement of the turntable 18, so the rotation position of the distance sensor 15 is calculated based on the detection signal of the second rotary encoder 28, which serves as a rotation sensor. The controller MC controls the fourth motor device 24 based on the shape data of the eyeglass lens 11 and the detection signal from the second rotary encoder 28 to rotate the turntable 18 counterclockwise and position the distance sensor 15 at the edge position of the eyeglass lens 11. The controller MC then controls the fourth motor device 24 to rotate the distance sensor 15 across the diameter and stops it at the edge position of the opposing eyeglass lens 11 based on the shape data of the eyeglass lens 11 and the detection signal from the second rotary encoder 28.The controller MC controls the driving of the fourth motor device 24 in the reverse direction so that the distance sensor 15 traverses in the opposite direction (i.e., toward the starting point) at the timing of the next 30-degree step. Then, the controller MC controls the driving of the fourth motor device 24 so that this reciprocating motion is repeated a total of 12 times in synchronization with the 30-degree step rotation of the rotary holder 12. In other words, the controller MC controls the driving of the fourth motor device 24 so that the distance sensor 15 reverses and traverses alternately at odd-numbered points and even-numbered points.

[0025] C. Acquisition of Distance Data 1. The controller MC controls the first motor device 14 to temporarily stop the rotating holder 12 at each point in the 30-degree steps in B.1. While the rotating holder 12 is stopped, the controller MC controls the fourth motor device 24 to rotate the distance sensor 15, which is positioned at the edge of the eyeglass lens 11, across the diameter as shown in B.2. The distance sensor 15 acquires distance data in the diameter direction at each step angle. At this time, the direction of emission of the detection light from the distance sensor 15 remains approximately normal to the curved lens surfaces 11A and 11B. Because the diameter position of the distance sensor 15 depends on the rotation angle of the swivel table 18 (i.e., the rotation angle of the distance sensor 15 is the rotation angle of the swivel table 18 itself), the controller MC associates the distance data measured by the distance sensor 15 at a predetermined rotation angle (swivel angle) with the measurement angle using the second rotary encoder 28 and stores the data. In MODE 1, for example, 10 distance data points are acquired and stored at equal intervals in the diameter direction of the eyeglass lens 11. Distance data is acquired simultaneously for the lens surfaces 11A and 11B of the eyeglass lens 11. At this time, since the pair of distance sensors 15 are always equally spaced, the advancement of one sensor results in the retreat of the other sensor. Because the eyeglass lens 11 is a meniscus lens, the concave and convex curves on the front and back surfaces are opposite, so the detection light can be irradiated from a direction approximately normal to either lens surface 11A or 11B.

[0026] 2.B.3., 10 distance data points can be acquired for each of the front and rear lens surfaces 11A and 11B of the eyeglass lens 11 in 12 directions at 30-degree intervals. While these data points can be used as shape data for the lens being measured, because they represent points on the curved surface of the lens, it is more convenient to project them onto a plane and convert them into planar data. The conversion theory by which the controller MC converts and stores these distance data into planar coordinates is explained with reference to Figures 4 and 5. Now, consider projecting the position p where the distance sensor 15 measured the distance on the rear lens surface 11B of the eyeglass lens 11 onto planar coordinates. Let p1 be the point where the position p, where the rotation angle is θ, intersects with the locus of a circle with a radius of rotation R on the optical axis of the detection light, and let D be the distance from position p to point p1. Furthermore, let p2 be the point where the perpendicular line from position p, perpendicular to the x-y plane coordinate system, intersects with the radius of rotation R. A right-angled triangle is formed by connecting p-p1-p2, as shown in Figure 5. This triangle is similar to a right triangle connecting the center of rotation O, position p, and T (the intersection of the horizontal line passing through position p and the perpendicular line passing through the center of the lens). From these relationships, if the horizontal distance from the center of the lens to position p is r (the distance from T to position p), and the height from the center of rotation O to the horizontal line passing through position p is z, the three-dimensional position data for position p is as follows: r = (R - D) sin θ z = (R - D) cos θ As shown in Figure 6, in the eyeglass lens 11 projected on the xy plane coordinate system, position p is indicated by the angle φ between the horizontal line r and the lens, which is stopped and controlled at a step angle of 30 degrees. Therefore, angle data can be obtained as appropriate using the first rotary encoder 10, and the positions in the x-axis and Y-axis directions can be determined using trigonometric functions.

[0027] Next, MODE 2 will be explained. In MODE 2, the controller MC executes the following control. A. Input of numerical values ​​according to the lens curve This is the same as in MODE 1. B. Operation of the rotating holder and distance sensor In MODE 2, the controller MC executes the following control. 1. The controller MC controls the fourth motor device 24 to rotate the turntable 18 and rotate the distance sensor 15 mounted on the sub-actuator 19 along the eyeglass lens 11. The controller MC controls the turning reference position, i.e., the fourth motor device 24, to rotate the turntable 18 and rotate the distance sensor 15 so that it crosses in the radial direction from the geometric center of the eyeglass lens 11. At that time, the controller MC controls to stop the fourth motor device 24 so that the distance sensor 15 temporarily stops at a predetermined position (interval). Since the rotation position of the distance sensor 15 is calculated based on the detection signal of the second rotary encoder 28, which functions as a rotation sensor, if the rotation sensor 15 repeatedly moves, stops, and moves in radial directions at intervals of 3 mm, for example, the controller MC controls the fourth motor device 24 to stop temporarily based on the detection signal of the second rotary encoder 28 that corresponds to the displacement of 3 mm. 2. Meanwhile, the controller MC controls the first motor device 14 to rotate the rotating holder 12 clockwise. The controller MC starts driving the first motor device 14 using the stopping of the fourth motor device 24 in B.1. as a trigger, and stops driving the first motor device 14 when it determines that the rotating holder 12 has rotated 360 degrees based on the detection signal of the first rotary encoder 10. Using the stopping of the first motor device 14 as a trigger, the controller MC controls the fourth motor device 24 to drive again, rotate the rotating table 18, move the distance sensor 15 to the next position, and stop it again. In MODE 2, the distance sensor 15 is moved outward in stages by repeating a move-stop-move sequence to a position that corresponds to a preset diameter of the eyeglass lens 11. Then, each time the distance sensor 15 stops, the first motor device 14 is controlled to rotate the rotating holder 12 360 degrees clockwise.When the distance sensor 15 determines that the eyeglass lens 11 has reached the end position based on the detection signal from the second rotary encoder 28, the fourth motor device 24 is controlled to return the swivel table 18 to the swivel reference position.

[0028] C. Acquisition of Distance Data 1. The controller MC rotates the eyeglass lens 11 at the timing when the distance sensor 15 stops every 3 mm of movement in B.1. to acquire distance data in the circumferential direction. At this time, the direction of emission of the detection light from the distance sensor 15 moves while maintaining a direction generally normal to the curved lens surfaces 11A and 11B. Distance data is acquired for each concentric revolution. The controller MC associates the distance data measured by the distance sensor 15 at a predetermined rotation angle (turning angle) with the measurement angle using the second rotary encoder 28 and stores it. In MODE 2, for example, 12 distance data items are acquired and stored at equal intervals around the circumference of the eyeglass lens 11. The conversion and storage of the acquired distance data onto planar coordinates is the same as above, so a detailed explanation will be omitted. Distance data is acquired simultaneously for the lens surfaces 11A and 11B of the eyeglass lens 11.

[0029] The above-described configuration of the first embodiment provides the following advantages. (1) Since the shape of the lens surface can be measured from the normal direction or a direction close to the normal direction, the reflected light of the white light irradiated from the distance sensor 15 can be reliably received, reducing missing or erroneous detections in distance data and enabling accurate measurement of the lens shape. (2) Since the radius of rotation of the distance sensor 15 can be changed according to the lens curve, the lens surface can be scanned in the normal direction or a direction close to the normal direction along a curve that is as close as possible to the lens curvature. This allows the reflected light of the white light irradiated from the distance sensor 15 to be reliably received, reducing missing or erroneous detections in distance data and enabling accurate measurement of the lens shape. (3) The two linear actuators 17, 19 and the rotating table 18 rotate the distance sensor 15 along the lens curve, realizing a structure that allows the radius of rotation of the distance sensor 15 to be changed when it rotates, which simplifies the system structure, makes it less susceptible to malfunction, and enables low-cost implementation. (4) In MODE 1 and MODE 2 control, either the distance sensor 15 or the eyeglass lens 11 is stationary, which simplifies the movement of the sensor rotation mechanism 13 and makes control easier. (5) The distance sensor 15 is configured to rotate along the lens curve, so the distance sensor 15 does not come into contact with the curved eyeglass lens 11. (6) When changing the rotation radius, the slide tables 21 and 23 of the actuators 17 and 19 simultaneously move in opposite directions up and down to cancel the amount of movement, so the rotation radius can be changed while the lens remains in a fixed position. (7) Because the distance sensor 15 is located on the front and back of the eyeglass lens 11 and the eyeglass lens 11 is a meniscus lens, the concave and convex curves are reversed and the lens surfaces are arranged approximately parallel, so one system can simultaneously measure the front and back lens surfaces 11A and 11B.

[0030] (Embodiment 2) In Embodiment 1, the case where the eyeglass lens 11 to be measured is a meniscus lens was described. However, in Embodiment 2, a lens shape measurement system will be described for simultaneously measuring the front and back surfaces of a convex or concave lens other than a meniscus lens. In Embodiment 2, the eyeglass lens 51 is illustrated and described as a convex lens, but measurements can also be performed on a concave lens. Note that components identical to those in the configuration of Embodiment 1 are designated by the same reference numerals and detailed descriptions will be omitted. Figure 8 is a schematic diagram illustrating an overview of the main components of the lens shape measurement system of this embodiment. The lens shape measurement system includes a rotating holder 12 that accommodates the eyeglass lens 51 to be measured and a sensor rotation mechanism 52. Descriptions of the rotating holder 12, the first motor device 14 that rotates the rotating holder 12, the first rotary encoder 10 that detects the rotation angle, and other components will be omitted. The following description will focus primarily on the sensor rotation mechanism 52. The sensor rotation mechanism 52 includes a main actuator 55 and two sub-actuators 56, one above the other. The sub-actuators 56 are supported by the main actuators 55 via the respective rotary tables 18 .

[0031] The main actuator 55 is an electric actuator and includes two slide tables 57 that are driven by the built-in second motor device 20 and slide linearly in the longitudinal direction. The main actuator 55 includes a threaded rod (not shown) that converts the rotational force of the motor into a linear force, and the slide tables 57 are moved by the rotation of the threaded rod. The male thread of the threaded rod is divided into right-handed and left-handed (reverse thread) at the center in the longitudinal direction, and when the second motor device 20 rotates the threaded rod, the upper and lower slide tables 57 move toward or away from each other so that the movement distances are equal, based on the center of the main actuator 55. In other words, the two slide tables 57 always move in opposite directions. The sub-actuator 56 is also an electric actuator and includes a slide table 58 that is driven by the built-in third motor device 22 and slides linearly in the longitudinal direction. The two upper and lower sub-actuators 56 are respectively mounted on different slide tables 57 on the rotating table 18, and when the slide table 57 of the main actuator 55 is driven, the sub-actuators 56 move the same distance in opposite directions together with the rotating table 18. A sensor holder 60 is fixed to the slide table 59 of each sub-actuator 56. The sensor holder 60 has one arm 61, and a distance sensor 15 is attached to each arm 61. The pair of distance sensors 15 are arranged so that their white light emission ports face each other. The pair of distance sensors 15 are arranged above and below the eyeglass lens 51 held by the rotating holder 12, sandwiching the eyeglass lens 51 while maintaining a distance from the eyeglass lens 51. Unlike the first embodiment, the sensor holder 60 supports only one distance sensor 15, and the distance between the two upper and lower distance sensors 15 varies depending on the thickness of the lens.

[0032] In the lens shape measurement system of the second embodiment having such a configuration, the control of the first and second motor devices 14, 20 is the same as in the first embodiment, and although there are two third and fourth motor devices 22, 24, one above the other, they can be controlled so that the behavior of the swivel table 18, the sub-actuator 56, the sensor holder 60, and the distance sensor 15 is mirror-symmetrical above and below. The "A. Input of numerical values ​​according to the lens curve," "B. Operation of the rotating holder and distance sensor," and "C. Acquisition of distance data" of the first embodiment are the same as those of the first embodiment. The second embodiment thus achieves the same effects as those of (1) to (5) of the first embodiment.

[0033] (Embodiment 3) Embodiment 3 is an example of the above-described embodiment 1 or 2, in which rotational runout occurring when the rotating holder 12 rotates relative to the table is corrected. In embodiment 3, the configuration of the lens rotation mechanism around the rotating holder 12 is described in more detail, and overlapping content already described in embodiments 1 and 2 is omitted. As shown in FIGS. 9 and 10 , the lens rotation mechanism includes a table 71 on which the rotating holder 12 is placed, a ring gear 72 and pinion 73 fixed to the rotating holder 12, a first motor device 14, and the like. The rotating holder 12 is a ring-shaped aluminum alloy body with a circular outer periphery in a plan view, and an outer ring 12A and an inner ring 12B are connected via a bearing 74. A circular through-hole 76 communicating vertically is formed in the inner ring 12B. Three catch arms 75 are attached to the top surface of the inner ring 12B to press the eyeglass lenses 11, 51 from the outer periphery with a biasing force, thereby holding the eyeglass lenses 11, 51 in the air. 10 shows the state in which the eyeglass lenses 11, 51 are held by the catch arms 75. The inner ring 12B can be locked against rotation relative to the outer ring 12A by a locking device (not shown) and fixed at any phase position. A ring gear 72 is fixed to the outside of the outer ring 12A so as to surround the entire circumference of the rotary holder 12. A pinion 73 arranged on the upper surface of the table 71 is engaged with the ring gear 72, and the rotation shaft of the pinion 73 is connected to the first motor device 14.

[0034] A circular through-hole 82 that communicates vertically is formed in the center of the aluminum alloy table 71, and the rotary holder 12 is fitted to the inner peripheral surface surrounding the through-hole 82 of the table 71 via a bearing 77. In other words, with the eyeglass lenses 11, 51 fixed by the inner peripheral ring 12B, the rotary holder 12 is rotatably supported by the bearing 77 relative to the table 71. Therefore, when the pinion 73 is rotated by the first motor device 14 and drive is transmitted to the ring gear 72, runout of the bearing 77 due to rotation or runout due to collision of the rotation transmission member may occur. A ring portion 78 that protrudes downward is formed on the outer peripheral ring 12A of the rotary holder 12, which is engaged with the inner ring of the bearing 77. The bottom surface of the ring portion 78 is a flat ring-shaped surface that is concentric with the eyeglass lenses 11, 51. An L-shaped protrusion 79 is formed below the table 71. The tip of the protrusion 79 is bent at a right angle and extends toward the rotating holder 12. An electrostatic sensor 80 serving as a second distance sensor is attached to the front of the protrusion 79 with its detection surface facing upward. The electrostatic sensor 80 is positioned so that its detection surface faces the bottom surface of the ring portion 78 as a target, and is always spaced 0.5 mm apart when the rotating holder 12 is free of rotational runout. In this third embodiment, two electrostatic sensors 80 are provided, positioned 180 degrees apart. As shown by the dashed-dotted line in FIG. 10 , the line segment P connecting the two electrostatic sensors 80 extends in the same direction as the line segment Q, which indicates the rotation direction of the distance sensor 15 as it rotates along the lens curve. In other words, the distance sensor 15 moves while rotating between the two electrostatic sensors 80.

[0035] Next, the electrical configuration of the computer device 29 will be described based on the block diagram of FIG. 11. Note that components not directly related to the present invention will be omitted. The controller MC of the computer device 29 is connected to the distance sensor 15, the first to fourth motor devices 14, 20, 22, and 24, the first and second rotary encoders 10 and 28, the monitor device 30, the keyboard 31, the mouse 32, and the like via interfaces (not shown). These components are the same as those in the first and second embodiments, and therefore will not be described here. In the third embodiment, an electrostatic sensor 80 is also connected to the controller MC. Next, a control method will be described that adds correction for rotational shake using the electrostatic sensor 80, which is executed by the controller MC when measuring the shape of the lens surface using this system. In this third embodiment, the method will be applied to the method of MODE 1 of the first embodiment as an example. "A. Input of numerical values ​​according to the lens curve" and "B. Operation of the rotating holder and distance sensor" are the same as those in the first embodiment. C. Acquisition of Distance Data 1. The controller MC performs B.1. At each point in 30-degree steps in A, B, C, D, E ...Since the eyeglass lens 11 is a meniscus lens, the concave and convex curves on the front and back are opposite to each other, so that the detection light can be irradiated from a direction substantially normal to either of the lens surfaces 11A and 11B.

[0036] In embodiment 3, the controller MC measures the distance to the bottom surface of the ring portion 78 on the rotating holder 12 side at each point in 30-degree increments in B.1. using the electrostatic sensor 80, and calculates the tilt α (angle) of the rotating holder 12 based on the difference. An example of a specific method for calculating the tilt α is described with reference to FIG. 13 . The coordinates of the two electrostatic sensors 80 at a certain rotation phase are (x1, y1) and (x2, y2), respectively. In the coordinates, the x-axis direction represents the distance from the center of rotation, for example, and a specific numerical value can be assigned. The y-axis direction represents the height of each electrostatic sensor 80 from a reference horizontal plane. Then, a line L (y = ax + b) connecting (x1, y1) and (x2, y2) is determined. Line L can be obtained by solving simultaneous equations with line L for a and b using the formula in Mathematical Formula 1. Since the slope a of line L can be expressed as a = tan(α), the slope α is determined from this inverse function.

[0037]

[0038] In addition, in this third embodiment, the eyeglass lens 11 is fixed to the catch arm 75 of the rotating holder 12 before rotation, and the tilt between the rotating holder 12 and the table 71 is adjusted before the performance begins. This state is considered to be the zero level (i.e., the state in which the line P is horizontal), and the tilt α is calculated from the difference between the two electrostatic sensors 80 in 30-degree increments. If the tilt α exists, the position from which the distance data was acquired must be converted to a position without tilt. In this third embodiment, the controller MC uses the tilt α to rotate the measurement position (coordinate transformation) using Equation 2, and then translates it in the y-axis direction (coordinate transformation) using Equation 3, thereby moving the two-dimensional coordinates to the correct lens surface without tilt. Here, the x-axis direction is the radial direction of the lens, and the y-axis direction is the thickness direction of the lens. The line P connecting the two electrostatic sensors 80 extends in the same direction as the line Q, which indicates the rotation direction of the distance sensor 15 that rotates along the lens curve. Therefore, the calculation is relatively simple, as it is only necessary to correct the tilt of the two-dimensional coordinates in the rotation direction. This coordinate transformation process will be explained with reference to FIG. 12. In FIG. 12, the actually measured spectacle lens 11A is shown by a solid line, and the spectacle lens 11B, which is assumed to be in a correctly horizontal position, is shown by a virtual line. A certain point (Px, Py) on the spectacle lens 11A is projected onto a corresponding point (Pi, Pj) on the spectacle lens 11B. In order to cancel the tilt α of the spectacle lens 11A shown by the solid line, Equation 2 is first applied. This essentially involves rotating the tilted line P0 so that it becomes a horizontal line P1. Next, since the centers of rotation of the spectacle lens 11A and the spectacle lens 11B are shifted relative to each other, Equation 3 is applied to move the corresponding coordinate of the spectacle lens 11B in its original correct position.

[0039]

[0040]

[0041] In 2.B.3., 10 pieces of distance data can be obtained for each of 12 directions at 30-degree intervals for the front and back lens surfaces 11A and 11B of the eyeglass lens 11. These data can be used as shape data for the lens to be measured as is, but because they are points on the curved surface of the lens, it is more convenient to project them onto a plane and convert them into planar data. In this case, if there is a tilt α as described above, coordinates with the tilt corrected will be used. The specific calculation method below is the same as in embodiment 1, so explanation will be omitted.

[0042] In addition to the effects of the first and second embodiments, the third embodiment also provides the following unique effects: (1) Even if there is a non-horizontal rotational phase position due to wobble caused by rotational runout between the rotary holder 12 and the table 71, the tilt α is canceled out, making it possible to measure the lens surface shape more accurately. (2) Because the rotation direction (straight line Q) and the straight line P connecting the two electrostatic sensors 80 are arranged to coincide, calculations for canceling the tilt α need only consider the planar direction, making the calculation easier.

[0043] The above-described embodiments are merely specific examples for illustrating the principles and concepts of the present invention. In other words, the present invention is not limited to the above-described embodiments. The present invention can also be embodied in the following modified forms, for example: The mechanical configuration of the above-described embodiments is merely an example. It may be realized using other configurations. For example, while the above configuration uses two linear actuators 17 and 19 and a rotating table 18 to rotate the distance sensor 15 along the lens curve, it may also be realized using a multi-axis robot. The type of distance sensor 15 may be changed. In the above-described embodiments, the rotation radius of the distance sensor 15 is set to roughly follow the lens curve before rotating. However, when measuring lenses with variable lens curves, such as aspherical lenses or progressive-addition lenses, the rotation radius may be controlled to change in accordance with the lens curve during rotation. The MODE 1 and MODE 2 controls in the above-described embodiment 1 are merely examples. In these controls, either the distance sensor 15 or the eyeglass lens 11 is stationary during measurement by the distance sensor 15, but both may be controlled to move. For example, the distance sensor 15 may be controlled to rotate the eyeglass lens 11 so that it crosses the geometric center of the eyeglass lens 11 in the radial direction. In this case, the scanning line of the distance sensor 15 traces a spiral trajectory on the lens surface. The number of distance data acquired in the control of MODE 1 and MODE 2 of embodiment 1 is merely an example, and the distance data may be acquired more finely (i.e., at a higher density). In MODE 1 and MODE 2 of embodiment 1, distance data is acquired based on a predetermined rotation angle (orbital angle) determined by the second rotary encoder 28. However, the distance data may be acquired at predetermined timings based on other information instead of the angle, such as the time it takes for the eyeglass lens 11 (rotating holder 12) to rotate once. In embodiments 1 and 2, the distance data is acquired by simultaneously measuring the front and back surfaces of the lens, but this does not have to be simultaneous.Although the distance sensor 15 is a confocal sensor that uses white light from a multi-lens optical system as detection light, other types of distance sensors may be used. For example, a distance sensor that uses laser light or maser light as detection light may be used in the system. In the above example, the eyeglass lens 11 is positioned horizontally (with its optical axis vertical), but the eyeglass lens 11 does not have to be positioned horizontally. However, since the eyeglass lens 11 rotates, it is preferable to position it horizontally to prevent problems caused by bearing wear on the rotation axis. In the above-described third embodiment, the present invention is described as being applied to MODE 1 of the first embodiment, but it may also be applied to other embodiments. For example, it may be applied to MODE 2 or MODE 2 of the first embodiment. It may also be applied to control other than MODE 1 and MODE 2. In the third embodiment, the rotating holder 12 and the table 71 are initially adjusted to eliminate tilt. However, the rotating holder 12 may actually be rotated, and calculations may be performed assuming that the rotating holder 12 is horizontal, for example, based on the average or minimum value of the obtained distances. The key point is to determine a reference horizontal line for calculations. Although the two electrostatic sensors 80 are installed on the table 71 side, they may also be installed on the rotating holder 12 side. Furthermore, three or more electrostatic sensors 80 may also be installed. A distance sensor other than the electrostatic sensor 80 may also be used. While the above description exemplifies the case of measuring the surface shape of an eyeglass lens, lenses other than eyeglass lenses, such as the objective and eyepiece lenses of a telescope or optical lenses such as lenses in a magnifying glass, may also be measured. The present invention is not limited to the configurations described in the above embodiments. The components of each embodiment and modification may be arbitrarily selected and combined. Furthermore, any component of each embodiment or modification may be arbitrarily combined with any component described in the Summary of the Invention, or any component embodying any component described in the Summary of the Invention. It is intended to obtain rights to these designs through amendments or divisional applications of this application. It is also intended to obtain rights to the entire design or partial design by filing a conversion application to a design application.The drawings depict the entire device in solid lines, but they also include partial designs claimed for parts of the device. For example, a partial design may be a part of the device, or a part of the device regardless of the part. A partial design may be a part of the device, or a part of that part.

[0044] 11... eyeglass lens, 12... rotating holder as a rotation mechanism, 15... distance sensor, 13... sensor rotation mechanism as a holding mechanism and attitude control mechanism, 25... sensor holder as a holding mechanism.

Claims

1. A measurement system for measuring the lens surface shape of at least one of the front and back sides of a lens, comprising: a rotation mechanism that holds the lens and rotates it in a circumferential direction; a distance sensor that irradiates detection light onto the lens surface to be measured and measures distance based on the reflected light of the detection light from the lens surface; a holding mechanism that holds the distance sensor; and an attitude control mechanism that moves the distance sensor in a direction transverse to the lens surface while maintaining the distance from the lens surface, and controls the attitude of the holding mechanism as the distance sensor moves so that the detection light is irradiated from a normal direction or a direction close to the normal direction onto the lens surface to be measured.

2. The lens surface shape measurement system described in claim 1, characterized in that the attitude control mechanism is configured as follows: a first drive unit mounted with the holding mechanism and moving the distance sensor linearly back and forth; a second drive unit mounted with a rotation mechanism and moving the rotation mechanism linearly back and forth; the first drive unit being mounted on the rotation mechanism; the direction of movement of the distance sensor and the direction of movement of the rotation mechanism being arranged parallel to each other; the rotation mechanism being moved back and forth to change the distance from the rotation center of the rotation mechanism to the distance sensor, thereby adjusting the rotation radius of the rotation mechanism, and the rotation mechanism being controlled with the adjusted rotation radius to rotate the distance sensor in a curve corresponding to the curvature of the curve of the lens surface; and maintaining the distance between the lens arranged in a fixed position and the distance sensor by moving the distance sensor in a direction opposite to the movement direction of the rotation mechanism by an amount of movement that is the same as or approximately the amount of movement when the rotation mechanism moves back and forth.

3. The lens surface shape measurement system of claim 1, wherein the distance sensor moves transversely between the center and the periphery of the lens surface.

4. A lens surface shape measurement system as described in claim 1 or 2, characterized in that the distance sensors are arranged in positions facing the front and back lens surfaces of the lens on either side of the lens, and the lens surface shapes of the front and back of the lens are measured simultaneously by different distance sensors.

5. A lens surface shape measuring system as described in claim 1 or 2, characterized in that it has a calculation means for calculating the shape of the lens surface based on distance data at multiple points on the lens surface obtained by scanning with the distance sensor which moves relatively across the rotating lens and the lens surface.

6. The lens surface shape measurement system described in claim 1, characterized in that the rotation mechanism comprises a rotating unit that rotates together with the lens and a holding unit that holds the rotating unit, one or more second distance sensors are arranged on the holding unit side to enable measurement of the distance to a target on the rotating unit side, and when the measured distance changes with the rotation of the rotating unit, the distance data of the lens surface is corrected based on the amount of change measured by the second distance sensor.

7. The lens surface shape measurement system described in claim 1, characterized in that the rotation mechanism comprises a rotating unit that rotates together with the lens and a holding unit that holds the rotating unit, one or more second distance sensors are arranged on the rotating unit side to enable measurement of the distance to a target on the holding unit side, and when the measured distance changes with rotation of the rotating unit, the distance data of the lens surface is corrected based on the amount of change measured by the second distance sensor.

8. A lens surface shape measurement system as described in claim 6 or 7, characterized in that two of the second distance sensors are positioned 180 degrees apart across the center of rotation of the lens, and the amount of change in distance is obtained based on the difference between the measurement values ​​of the two second distance sensors.

9. The lens surface shape measuring system according to claim 8, wherein the distance sensor is moved so as to cross between the center and the outer periphery of the lens surface along a line segment connecting the two second distance sensors.

10. A lens surface shape measurement system as described in claim 6 or 7, characterized in that the target surface of the second distance sensor is a ring-shaped flat surface arranged along the outer peripheral shape of the lens.

11. A method for measuring the shape of at least one of the front and back lens surfaces of a lens, comprising: using a distance sensor that irradiates a detection light onto the object to be measured and measures the distance to the object to be measured based on the reflected light of the detection light from the lens surface; positioning the distance sensor so that the detection light is irradiated from a normal direction or a direction close to the normal direction of the lens surface to be measured; scanning the lens surface with the distance sensor in this position to obtain distance data at multiple points on the lens surface; and calculating the shape of the lens surface based on the multiple distance data obtained.

12. A method for measuring the shape of a lens surface as described in claim 11, characterized in that the lens rotates in a circumferential direction and the distance sensor is controlled to rotate along the curve of the lens surface in a direction intersecting the lens with the detection light being irradiated from a direction normal to or close to the normal to the lens surface.

13. The method for measuring the shape of a lens surface according to claim 12, wherein the distance sensor is controlled so as not to interfere with the lens surface when rotating.

14. A lens surface shape measurement system as described in any one of claims 11 to 13, characterized in that the distance sensors are arranged in positions facing the front and back lens surfaces of the lens on either side of the lens, and the lens surface shapes of the front and back of the lens are measured simultaneously by different distance sensors.

15. A method for measuring the shape of a lens surface according to any one of claims 11 to 13, characterized in that the detection light irradiated from the distance sensor is coherent light.

16. A method for measuring the shape of a lens surface described in any one of claims 11 to 13, characterized in that the lens is controlled to rotate in a circumferential direction and stop once every predetermined rotation angle, and the distance sensor is controlled to move in the diameter direction of the lens surface when the lens stops while facing the lens surface, and the distance data at multiple points is obtained as the sensor moves.

17. A method for measuring the shape of a lens surface described in any one of claims 11 to 13, characterized in that the distance sensor is controlled to stop at any of a plurality of stopping positions while moving in the radial direction of the lens while facing the lens surface directly, and a plurality of distance data are obtained by controlling the lens to rotate at each stopping position of the distance sensor.

18. A method for measuring the shape of a lens surface described in any one of claims 11 to 13, characterized in that the rotational shake of a rotating part that rotates together with the lens is measured by a second distance sensor from the side of a holding part that holds the rotating part, with the rotating part side as a target, and if the measured distance changes with the rotation of the rotating part, the amount of change is used as a correction value to correct the distance data and calculate the shape of the lens surface.

19. A method for measuring the shape of a lens surface described in any one of claims 11 to 13, characterized in that the rotational runout of a rotating part which rotates together with the lens is measured by a second distance sensor arranged on the rotating part side, with the holding part side which holds the rotating part as a target, and if the measured distance changes with the rotation of the rotating part, the amount of change is used as a correction value to correct the distance data and calculate the shape of the lens surface.

20. A method for measuring the shape of a lens surface as described in claim 18 or 19, characterized in that two of the second distance sensors are positioned 180 degrees apart across the center of rotation of the lens, and the amount of change in distance is obtained based on the difference between the measurement values ​​of the two second distance sensors.

21. The method for measuring the shape of a lens surface according to claim 20, further comprising moving the distance sensor so as to cross between the center and the outer periphery of the lens surface along a line segment connecting the two second distance sensors.

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