Workpiece holder

Abstract

This workpiece holder is for holding an outer peripheral edge of a plate-shaped workpiece and comprises: a holder body that surrounds an arrangement space in which the workpiece is arranged; a holding arm that is partially arranged within the holder body and has a tip movable between a first position where the tip approaches the center of the arrangement space and a second position where the tip is away from the center of the arrangement space; and an operation mechanism that is provided in the holder body and operates the holding arm so that the tip moves between the first position and the second position. A plurality of holding arms is dispersedly arranged in the arrangement space, and tips thereof abut on the outer peripheral edge of the workpiece at at least three positions to hold the workpiece.

Description

Workholder

[0001] The present invention relates to a workholder that holds a work that is an object of processing such as measurement or conveyance.

[0002] When performing processing such as measurement of optical characteristics on a plate-shaped work such as a spectacle lens, a workholder that mechanically holds the work is used. In order to process the entire surface of the work, a mechanism that grips the outer peripheral edge of the work is adopted. In the prior art described in Patent Document 1 below, a mold frame that surrounds the outer periphery of the work and a slider that slides so as to contact the work inside the mold frame are provided, and the work is gripped by the inner frame edge of the mold frame and one side of the slider, or the opposing sides of a pair of sliders arranged inside the mold frame.

[0003] Japanese Patent No. 6660508

[0004] In the conventional workholder described above, a concave portion is formed in the work contact portion in accordance with the shape of the outer peripheral edge of the circular work, and the work is held by fitting a part of the outer peripheral edge of the work into the concave portion. In such a conventional technique, when the shape of the outer peripheral edge of the work is different, a workholder having a concave portion corresponding to the shape is required, and it is necessary to prepare various types of workholders for works having various outer peripheral edge shapes.

[0005] Further, in the conventional workholder, since the pair of work contact portions are arranged to face each other along one direction, the force for gripping the work becomes only the force on a straight line in which the forces oppose each other, and a biased force acts and distortion is likely to occur in the work. Therefore, in the case of measuring the optical characteristics of a spectacle lens, for example, the distortion generated in the work affects the measurement accuracy, and there is a problem that it is difficult to realize an appropriate measurement of the optical characteristics.

[0006] An object of the present invention is to address such circumstances. That is, an object of the present invention is to enable one workholder to cope with works having various outer peripheral edge shapes, and to suppress distortion generated in the work by applying uniform force around the work when holding the work.

[0007] To solve these problems, the work holder of the present invention has the following configuration: A work holder for holding the outer edge of a plate-shaped workpiece, comprising: a holder body surrounding a space in which the workpiece is placed; a holding arm, partly disposed within the holder body, whose tip is movable between a first position approaching the center of the space and a second position away from the center of the space; and an operating mechanism provided within the holder body for operating the holding arm so that the tip moves between the first and second positions, wherein a plurality of holding arms are distributed around the space, and the tips of the holding arms contact the outer edge of the workpiece at least three or more points to hold the workpiece.

[0008] This is a perspective view showing the external configuration of the work holder according to the first embodiment. This is an exploded perspective view of the work holder according to the first embodiment. This is a top view of the holding arm and operating mechanism of the work holder according to the first embodiment, showing the tip of the work holder in a first position. This is a top view of the holding arm and operating mechanism of the work holder according to the first embodiment, showing the tip of the work holder in a second position. This is a top view of the holding arm and operating mechanism of the work holder according to the first embodiment, showing the tip of the work holder between the first and second positions, holding an eyeglass lens (workpiece). This is a bottom view of the holding arm and operating mechanism of the work holder according to the first embodiment, showing the tip of the work holder in a first position. This is an exploded perspective view of the work holder according to the second embodiment. This is a top view of the holding arm and operating mechanism of the work holder according to the second embodiment, showing the tip of the work holder in a first position. This is a top view of the holding arm and operating mechanism of the work holder according to the second embodiment, showing the tip of the work holder in a second position. This is a top view of the holding arm and operating mechanism of the work holder according to the second embodiment, showing the tip of the work holder between the first and second positions, holding an eyeglass lens (workpiece). This is a bottom view of the holding arm and operating mechanism of the work holder according to the second embodiment, showing the tip of the work holder in the first position.

[0009] Embodiments of the present invention will be described with reference to the drawings. In the following description, the same components as those shown in the drawings will be omitted from the description.

[0010] [First Embodiment] First, a first embodiment of the present invention (hereinafter also simply referred to as "the first embodiment") will be described with reference to Figures 1 to 4. The work holder 1 according to the first embodiment holds the outer edge of a workpiece that is the subject of processing such as measurement or transport, and is capable of holding not only workpieces with a circular outer edge shape, but also workpieces having a wide variety of other outer edge shapes.

[0011] In other words, the outer edge shape of a workpiece that can be held by the workpiece holder 1 shown in Figure 1 can include not only circles, but also ellipses, polygons (e.g., triangles, rectangles, trapezoids, etc.), polygons with rounded corners, and any other shape. Such workpieces are not particularly limited, but examples include eyeglass lenses, camera lenses, plates, cups, lids (caps), optical mirrors, polarizers, etc.

[0012] The work holder 1 according to the first embodiment may be installed in, for example, a lens optical properties measuring device (not shown) for measuring the optical properties of a lens, or a lens inspection device (not shown) for inspecting whether there are scratches, dirt, coating defects, etc. on the upper and lower surfaces of a lens. When such a device performs processing such as measurement, inspection, photography, and transport of a lens, the holder chuck (holder gripping part, not shown) of the actuator grips the work holder 1 holding the lens.

[0013] The eyeglass lens 20 shown in Figure 3C, which is an example of a workpiece, may be, for example, a transparent lens with a curved convex upper surface and a curved concave lower surface, and may be obtained by, for example, heat bending a substrate such as an optical sheet under heating. The outer edge shape of the eyeglass lens 20 is, for example, elliptical, but is not limited to this and may be other shapes, such as a triangle with rounded corners or a trapezoid with rounded corners.

[0014] As shown in Figures 1 and 2 (exploded perspective view), the work holder 1 according to the first embodiment comprises a holder body 2 that encloses an arrangement space 5 in an annular shape, for example, on which a workpiece (for example, an eyeglass lens 20) is placed, a plurality of holding arms 3 for holding the workpiece, and an operating mechanism 4 for operating the plurality of holding arms 3. Since the holding arms 3 contact the outer edge of any outer edge shape of a workpiece at least three or more points, as will be described later, to hold the workpiece, it is preferable that the number of holding arms 3 be an odd number of 5 or more. In the example shown in Figures 1 to 4, the number of holding arms 3 is 5, but it is not limited to this, and any odd number of 5 or more may be used.

[0015] The holder body 2 has a cover 21 (upper cover 22 and lower cover 23) that houses the operating mechanism 4. For example, both the upper cover 22 and the lower cover 23 have an annular disc shape centered on a central axis O. As shown in Figure 2 (exploded perspective view), the work holder 1 is constructed by housing the operating mechanism 4 inside the holder body 2, that is, between the upper cover 22 and the lower cover 23, and positioning a part of the holding arm 3 therein, and then joining the upper cover 22 and the lower cover 23 in that state. Although the shape of the holder body 2 (cover 21) shown in Figures 1 and 2 is annular, the shape of the inner and outer diameters of the holder body 2 (cover 21) is not limited to this, and other shapes such as rectangles or other polygons may be used.

[0016] Here, the thickness of the holder body 2 (height along the Y-axis direction in the illustration) is defined as the distance between the surface of the upper cover 22 (outer surface of the disc portion 225) and the surface of the lower cover 23 (outer surface of the disc portion 234) along the Y-axis direction in the illustration. The thickness of the workpiece (height along the Y-axis direction in the illustration) is defined as the distance between the highest and lowest points of the workpiece along the Y-axis direction in the illustration when the workpiece is viewed from the side. In this case, it is preferable that the thickness of the holder body 2 (height along the Y-axis direction in the illustration) is greater than the thickness of the workpiece held by the holding arm 3 (height along the Y-axis direction in the illustration). By doing so, for example, when the workpiece holder 1 holding the workpiece is placed on a mounting table or the like, the workpiece holder 1 contacts the mounting table or the like while the workpiece is elevated from the table or the like, thus preventing scratches on the workpiece and the adhesion of dirt. Furthermore, even if the work holder 1 is dropped during the handling process, since the surface of the workpiece does not protrude from the surface of the work holder 1, damage, scratches, and contamination of the workpiece can be prevented.

[0017] As shown in Figures 1 and 2, the upper cover 22 has a set of relatively small-diameter blind holes 221 to 223 formed at equal intervals from each other in the circumferential direction of the annular disc portion 225, corresponding to the mounting positions of the multiple retaining arms 3. An outer peripheral side portion 226 is provided around the entire circumference of the annular disc portion 225 of the upper cover 22. Inside the disc portion 225, there are multiple spaces 227B provided relative to the inner peripheral side portion 227A, allowing the retaining arms 3 protruding from the inner peripheral side portion 227A to move, depending on the arrangement of the retaining arms 3.

[0018] As shown in Figure 2, the lower cover 23 has relatively small diameter blind holes 233 formed at equal intervals from each other in the circumferential direction of the annular disc portion 234, corresponding to the mounting positions of the multiple retaining arms 3. An outer peripheral side surface portion 235 is provided around the entire circumference of the annular disc portion 234 of the lower cover 23. An inner peripheral side surface portion 236 is provided around the entire circumference of the inside of this disc portion 234.

[0019] Furthermore, the lower cover 23 has a pair of handle portions 231 formed on its outer peripheral side surface 235, projecting 180° opposite to each other with respect to the central axis O. For example, one transport actuator (not shown) grasps one of the handle portions 231 and moves. Then, when that transport actuator reaches the target position, it has another transport actuator (not shown) grasp the other handle portion 231 and transfer it. For example, the lower cover 23 of the work holder 1 has a pair of handle portions 231 formed to perform such handling.

[0020] According to the work holder 1 of the first embodiment, when the work holder 1 is transferred from one actuator (not shown) to another actuator (not shown), one handle portion 231 is grasped by one actuator while the other handle portion 231 is grasped by the other actuator. Therefore, reliable handling is possible with these actuators.

[0021] Furthermore, for example, a rotation mechanism (not shown) capable of rotating the work holder 1 up to 360° around a rotation axis P may be provided with a rotation actuator that grips one of the handle portions 231. In this rotation mechanism, for example, the rotation actuator connects the work holder 1 and the rotation actuator by gripping one of the handle portions 231, and this rotation actuator makes it possible to rotate (reverse) the work holder 1 by 180° around the rotation axis P shown in Figure 1. In a device that performs processing such as measurement, inspection, and photography on a workpiece, by providing such a rotation mechanism, after performing processing such as measurement on one side of the workpiece (e.g., the top surface), the work holder 1 can be quickly and stably reversed to perform the same processing on the opposite side of the workpiece (e.g., the bottom surface).

[0022] In other words, when processing one side of a workpiece (for example, the top side) and the opposite side (for example, the bottom side), it is not necessary to remove the workpiece from the workpiece holder 1 and flip it over; instead, the workpiece holder 1 itself, which holds the workpiece, can be flipped over. Therefore, with this workpiece holder 1, the workpiece can be flipped over without touching the workpiece.

[0023] In addition, the part of the work holder 1 that is gripped by the various actuators may be a part other than the handle portion 231.

[0024] In the work holder 1 according to the first embodiment, the five holding arms 3 are distributed around the arrangement space 5. In this work holder 1, the five holding arms 3 are provided at equal intervals from one another in the circumferential direction.

[0025] As shown in Figures 2 and 3A, the holding arm 3 has a first arm portion 311, a second arm portion 312, and a bent portion 310. The bent portion 310 connects one end of the first arm portion 311 and one end of the second arm portion 312 such that the longitudinal direction of the second arm portion 312 bends relative to the longitudinal direction of the first arm portion 311. A contact portion (pin) 32 is provided at the tip of the holding arm 3 (the end of the second arm portion 312 opposite to the bent portion 310 side). The holding arm 3 is positioned such that the second arm portion 312 and the contact portion 32 are located within the arrangement space 5 of the work holder 1.

[0026] An engaging projection 313 that protrudes downward is provided on the lower side of the bent portion 310 of the holding arm 3. Furthermore, a pivot shaft 311A ​​that protrudes upward (in the Y-axis direction shown in the figure) is formed at the base end of the holding arm 3 (the end of the first arm portion 311 opposite to the bent portion 310). This pivot shaft 311A ​​is rotatably supported in a stop hole 221 formed in the upper cover 22.

[0027] The contact portion (pin) 32 provided at the tip of the holding arm 3 has a cylindrical shape that extends in the thickness direction of the workpiece (Y-axis direction in the figure) in order to hold the workpiece. A pair of flange portions 33 are provided at both ends in the longitudinal direction of this cylindrical contact portion 32 in order to prevent the workpiece from falling from the contact portion (pin) 32. The flange portions 33 have an outer diameter that is slightly larger than the outer diameter of the contact portion (pin) 32.

[0028] The thickness of the holder body 2 and the length of the contact portion (pin) 32 are preferably 20 mm or less, and in this case, the outer diameter of the flange portion 33 is preferably 12 mm or less. Furthermore, when providing such a flange portion 33 on the contact portion 32, the length (amount of intrusion) of the flange portion 33 that extends from the outer edge of the workpiece onto the surface of the workpiece is preferably 3 mm or less, so as not to interfere with processing such as measurement, inspection, and photography of the upper and lower surfaces of the workpiece.

[0029] It should be noted that the work holder 1 does not necessarily need to have such a pair of flange portions 33 on the contact portion 32. In this case, the work holder 1 can hold a workpiece with a thickness greater than the distance between the pair of flange portions 33 by the contact portion 32.

[0030] In the holding arm 3, it is preferable that an anti-slip cushioning member 34 is provided on the outer circumference of the cylindrical contact portion (pin) 32, as shown in Figures 1 and 2. The material of the anti-slip cushioning member 34 is not particularly limited, but it may be made of a resin such as rubber.

[0031] The outer circumference of the contact portion 32 is covered with the anti-slip cushioning member 34, so that the contact portion 32 contacts the outer edge of the workpiece via the anti-slip cushioning member 34. As a result, when the workpiece holder 1 is moved, the workpiece (e.g., eyeglass lens 20) is prevented from slipping against the contact portion (pin) 32, and the workpiece is prevented from falling from the workpiece holder 1. In addition, because the anti-slip cushioning member 34 contacts the outer edge of the workpiece, the workpiece does not come into direct contact with the contact portion 32, thus preventing scratches or other damage to the workpiece and the contact portion 32. Alternatively, the outer circumference of the contact portion 32 could be left exposed without any covering, but considering these effects, it is preferable to provide the anti-slip cushioning member 34 on the outer circumference of the contact portion 32.

[0032] The operating mechanism 4 is provided within the cover 21 that constitutes the holder body 2, and operates the holding arm 3 so that the tip portion (contact portion 32) of the holding arm 3 moves between a first position (position in Figure 3A) where it approaches the center (central axis O) of the arrangement space 5 and a second position (position in Figure 3B) where it moves away from the center (central axis O) of the arrangement space 5. This operating mechanism 4 has a ring-shaped cam member 41 (Figures 2 and 3A) having an annular disc shape. This ring-shaped cam member 41 is arranged to surround the arrangement space 5. The ring-shaped cam member 41 has a set of substantially linear elongated cam holes 411A, substantially arc-shaped guide holes 411B, and relatively small diameter stop holes 411C formed at equal intervals from each other in the circumferential direction, corresponding to the mounting positions of the multiple holding arms 3.

[0033] As shown in Figure 3A, in the ring-shaped cam member 41, the cam hole 411A is formed such that the other end 411A-2 is located further radially outward than the other end 411A-1. The downward-projecting engagement projection 313 of the retaining arm 3 is engaged with this cam hole 411A. When the ring-shaped cam member 41 rotates around the central axis O, the engagement projection 313 engaged with the cam hole 411A moves between the one end 411A-1 and the other end 411A-2, causing the retaining arm 3 to rotate around the pivot axis 311A.

[0034] As shown in Figures 1 to 3A, an operating projection 412, which is operated by an actuator or the like, is provided on the outer peripheral surface of the ring-shaped cam member 41 so as to extend radially outward. By moving this operating projection 412 in the circumferential direction, the ring-shaped cam member 41 can be rotated in the circumferential direction about the central axis O, thereby changing the position of the tip of the retaining arm 3 that engages with the ring-shaped cam member 41 within the arrangement space 5.

[0035] Furthermore, as shown in Figures 2 and 3A, the operating mechanism 4 has an elastic member (for example, a coil spring) 421 that connects the upper cover 22 and the ring-shaped cam member 41 at a position adjacent to the tip of the first arm portion 311 of the holding arm 3. The elastic member 421 is not limited to a coil spring and may be other elastic members, such as other springs or rubber material.

[0036] A ring at one end of the elastic member 421 is attached to an engaging member 422 with its engaging projection facing upward, and a ring at the other end of the elastic member 421 is attached to an engaging member 423 with its engaging projection facing downward. The engaging member 422 that engages with the elastic member 421 engages with the stop hole 222 of the disc portion 225 of the upper cover, and the engaging member 423 that engages with the elastic member 421 engages with the stop hole 411C of the ring-shaped cam member 41 (Figure 2). As a result, the ring-shaped cam member 41 can rotate relative to the upper cover 22 around the central axis O in accordance with the expansion and contraction of the elastic member 421.

[0037] Furthermore, as shown in Figures 2 and 3A, the operating mechanism 4 has a guide pin 43 at another position adjacent to the tip of the first arm portion 311 of the holding arm 3. The engaging projection at the upper end of the guide pin 43 engages with the stop hole portion 223 of the disc portion 225 in the upper cover 22. The engaging projection at the lower end of the guide pin 43 engages with the guide hole portion 411B of the ring-shaped cam member 41 and, via a washer 45, engages with the stop hole portion 233 of the disc portion 234 in the lower cover 23 (Figure 2).

[0038] In this way, the guide pin 43 engages with the guide hole 411B of the ring-shaped cam member 41, with one end connected to the upper cover 22 and the other end connected to the lower cover 23, thereby guiding the movement of the ring-shaped cam member 41 along the holder body 2. The length of the guide hole 411B restricts the rotational range of the ring-shaped cam member 41.

[0039] The work holder 1 has a part of the holding arm 3 and the operating mechanism 4 covered by a holder body 2 which has upper and lower disc portions 225, 234, outer peripheral side portions 226, 235, and inner peripheral side portions 227A, 236. This prevents dust and other dirt attached to the operating mechanism 4, etc., from falling or spreading into the surroundings when the work holder 1 is moved, such as by inverting it. As a result, it prevents such dirt from falling into the device equipped with the work holder 1 or from adhering to the workpiece.

[0040] Next, the operation of the holding arm 3 in the work holder 1 according to the first embodiment will be described mainly with reference to Figures 3A to 3C and Figure 4. When the work holder 1 is in an unoperated state (original state), as shown in Figures 3A and 4, the tip portion (contact portion 32) of the holding arm 3 is in a first position (position in Figure 3A) that is close to the center of the arrangement space 5. In this unoperated state, the engaging projection 313 of the holding arm 3 is located at one end 411A-1 within the cam hole portion 411A of the ring-shaped cam member 41, as shown in Figures 3A and 4.

[0041] With the work holder 1 in that state, the operating projection 412 provided on the ring-shaped cam member 41 is gripped by an actuator or the like (not shown) and moved in the direction of the circumferential arrow T1. This rotates the ring-shaped cam member 41 by a predetermined angle α in the direction of the circumferential arrow T1 from the position shown in Figure 3A (Figure 4) around the central axis O (Figure 3B). One end of the elastic member 421 is connected to the upper cover 22 by an engaging member 422, and the other end is connected to the ring-shaped cam member 41 by an engaging member 423. Therefore, when the ring-shaped cam member 41 is rotated by a predetermined angle α in the direction of the circumferential arrow T1, the elastic member 421, due to its elasticity, biases the ring-shaped cam member 41 back to its original position (towards the direction of arrow T2, opposite to the direction of the circumferential arrow T1).

[0042] As described above, the cam hole 411A of the ring-shaped cam member 41 is formed such that the other end 411A-2 is located further radially outward than the other end 411A-1 (Figure 3A). Therefore, when the ring-shaped cam member 41 rotates by a predetermined angle α in the direction of the circumferential arrow T1, the position of the engaging projection 313 in the cam hole 411A moves from one end 411A-1 to the other end 411A-2 within the cam hole 411A, and the holding arm 3 rotates around the pivot axis 311A ​​such that the first arm portion 311 faces radially outward. As a result, the work holder 1 is in an open state (standby state) as shown in Figure 3B, that is, the tip portion (contact portion 32) of the second arm portion 312 of the holding arm 3 is in a second position (position in Figure 3B) away from the center of the arrangement space 5.

[0043] In the first embodiment, when the ring-shaped cam member 41 is rotated by a predetermined angle α in the direction of the circumferential arrow T1 around the central axis O to the position shown in Figure 3B, the substantially arc-shaped guide hole 411B rotates along the guide pin 43 that engages with the upper cover 22 and the lower cover 23. As a result, the work holder 1 can stably rotate the ring-shaped cam member 41 in the direction of the circumferential arrow T1 within the holder body 2.

[0044] While the workholder 1 is in the open state (standby state) as shown in FIG. 3B, the position of the operation projection 412 is temporarily fixed by an actuator or the like. Thereby, the ring-shaped cam member 41 holds the tip (contact portion 32) of the holding arm 3 at the second position (the position in FIG. 3B). In that state, the work is placed in the placement space 5. Thereafter, when an operation to release the temporary position fixing of the operation projection 412 by an actuator or the like is performed, due to the elasticity of the elastic member 421, the ring-shaped cam member 41 rotates toward its original position (in the direction of arrow T2 opposite to the circumferential direction arrow T1). <000009> By the rotation of this ring-shaped cam member 41, the ring-shaped cam member 41 releases the holding of the tip (contact portion 32) of the holding arm 3 at the second position in the second position (FIG. 3B), and simultaneously moves this tip toward the original first position (the position in FIG. 3A). During the movement, the contact portion 32 provided at the tip of the holding arm 3 comes into contact with the outer peripheral edge of the work, and the work is held by the workholder 1. At this time, if the work to be held is a circular work with the center of the work arranged at the center (central axis О) of the placement space 5, all of the contact portions 32 of the plurality of holding arms 3 will come into contact with the outer peripheral edge of the work. However, when the work to be held is a work of various non-circular shapes (for example, the spectacle lens 20 etc.), the contact portion 32 will come into contact with at least three locations on the outer peripheral edge of the work.

[0046] In the workholder 1 according to the first embodiment, due to the operation of the operation mechanism 4 provided with the aforementioned ring-shaped cam member 41, the five holding arms 3 that are dispersedly arranged with respect to the placement space 5 perform the same rotation operation. Therefore, while the tips (contact portions 32) of the five holding arms 3 move from the second position (the position in FIG. 3B) to the original first position (the position in FIG. 3A), for example, as shown in FIG. 3C, the tips (contact portions 32) of three holding arms 3 come into contact with the outer peripheral edge of the elliptical spectacle lens 20, which is an example of a work, located in the placement space 5.

[0047] Thus, in the workpiece holder 1 according to the first embodiment, the tip of the holding arm 3 (contact portion 32) contacts the outer peripheral edge of the spectacle lens 20, which is an example of the workpiece located in the placement space 5, at three locations. If the tip of the holding arm 3 (contact portion 32) contacts the outer peripheral edge of the spectacle lens 20 located in the placement space 5 at two locations, the force for gripping the spectacle lens 20 becomes only the force on a straight line where the forces oppose each other, and distortion is likely to occur in the spectacle lens 20 due to the action of the biased force.

[0048] According to the workpiece holder 1 according to the first embodiment, since the workpiece is held by contacting the outer peripheral edge of the workpiece at three or more locations, even if the outer peripheral edge shape of the workpiece is a shape other than a circle, such as an oval like the spectacle lens 20, a uniform force can be applied around the workpiece, and the distortion generated in the workpiece can be suppressed. Therefore, according to the workpiece holder 1, workpieces with any outer peripheral edge shape can be stably held.

[0049] That is, according to the workpiece holder 1 according to the first embodiment, one workpiece holder 1 can handle workpieces having a variety of outer peripheral edge shapes, and when holding the workpiece, a uniform force can be applied around to suppress the distortion generated in the workpiece.

[0050] When removing the workpiece held by the holding arm 3 from the workpiece holder 1 thereafter, again, the operation protrusion 412 is gripped by an actuator or the like and moved in the direction of the circumferential arrow T1, and the ring-shaped cam member 41 is rotated in the direction of the arrow T1. As a result, the tip of the holding arm 3 (contact portion 32) is moved toward the second position (the position in FIG. 3B), and the spectacle lens 20 is removed from the holding arm 3.

[0051] With a device equipped with such a work holder 1 (such as the aforementioned lens optical characteristic measuring device), the work holder 1 can stably hold a workpiece regardless of its peripheral edge shape, resulting in improved reproducibility and stability in processes such as measurement, inspection, photography, and transport. Furthermore, with a device equipped with this work holder 1, for example, during photography, the work holder 1 can be controlled to rotate around the rotation axis P using an actuator or the like, thereby rotating the workpiece while performing processes such as photography. For example, in such a device, during photography, the work holder 1 can be controlled to rotate (invert) 180° around the rotation axis P, thereby inverting the workpiece while taking a photograph.

[0052] Furthermore, with a device equipped with such a work holder 1, when transferring the work holder from one actuator to another, one actuator can grasp one handle portion 231 of the work holder 1, while the other handle portion 231 of the work holder 1 is grasped by the other actuator, thus enabling reliable handling.

[0053] Furthermore, in the work holder 1 according to the first embodiment, the operating mechanism 4 is equipped with an elastic member 421 so that it is always in an idle state, and only when it is to be opened (standby state) does the operating projection 412 provided on the ring-shaped cam member 41 need to be grasped and moved. In other words, in a device equipped with this work holder 1, there is no need to provide a dedicated mechanism (a dedicated actuator, etc.) for switching the work holder 1 between the idle state and the open state, and therefore there is no need to consider the routing of cables connected to such a dedicated mechanism.

[0054] [Second Embodiment] Next, a second embodiment of the present invention (hereinafter also simply referred to as the "second embodiment") will be described with reference to Figures 5 to 7. The work holder 1a according to the second embodiment has the same external configuration as the work holder 1 according to the first embodiment shown in Figure 1. Similar to the work holder 1 described above, this work holder 1a is capable of holding the outer edges of workpieces having not only circular outer edge shapes but also a wide variety of other outer edge shapes. The same components in this work holder 1a as in the work holder 1 described above will be denoted by the same reference numerals and their description will be omitted.

[0055] As shown in Figures 5 (exploded perspective view), 6A, and 7, the work holder 1a according to the second embodiment comprises a holder body 2a that encloses an arrangement space 5 in an annular shape, for example, where a workpiece (for example, an eyeglass lens 20) is placed, a plurality of holding arms 3a distributed around the arrangement space 5 to hold the workpiece, and an operating mechanism 4a for operating the plurality of holding arms 3a. The work holder 1a according to the second embodiment is equipped with an elastic member 421a for individually rotating each holding arm 3a, and has a configuration in which all holding arms 3a abut against the outer edge of the workpiece.

[0056] In the work holder 1a according to the second embodiment having such a configuration, the holding arms 3a, which are distributed in the arrangement space 5 and rotate individually, contact the outer edge of the workpiece at least three or more points. Therefore, it is preferable that the number of holding arms 3a be an even or odd number of three or more. In the example shown in Figures 5 to 7, the number of holding arms 3 is 5, but it is not limited to this, and any number of even or odd numbers of three or more is acceptable.

[0057] As shown in Figure 5, the holder body 2a has a cover 21a (for example, an annular disc-shaped upper cover 22a and a lower cover 23a) that houses the operating mechanism 4a. As shown in Figure 5 (exploded perspective view), the work holder 1a is constructed by housing the operating mechanism 4a inside the holder body 2a, that is, between the upper cover 22a and the lower cover 23a, and positioning a part of the holding arm 3a, and then joining the upper cover 22a and the lower cover 23a in that state. Although the shape of the holder body 2a (cover 21a) shown in Figure 5 is annular, the shape of the inner and outer diameters of the holder body 2a (cover 21a) is not limited to this, and other shapes such as rectangles or other polygons may be used.

[0058] On the upper cover 22a, a set of relatively small-diameter blind holes 221a to 223a is formed at equal intervals from each other in the circumferential direction of the annular disc portion 225a, corresponding to the mounting positions of the multiple retaining arms 3. On the lower cover 23a, a set of relatively small-diameter blind holes 232a and 233a is formed at equal intervals from each other in the circumferential direction of the annular disc portion 234a, corresponding to the mounting positions of the multiple retaining arms 3.

[0059] In the work holder 1a according to the second embodiment, the five holding arms 3a are distributed around the arrangement space 5. In this work holder 1a, the five holding arms 3a are provided at equal intervals from one another in the circumferential direction.

[0060] As shown in Figures 5 and 6A, the holding arm 3a has a first arm portion 311a, a second arm portion 312a, and a bent portion 310a. The bent portion 310a connects one end of the first arm portion 311a and one end of the second arm portion 312a such that the longitudinal direction of the second arm portion 312a is bent relative to the longitudinal direction of the first arm portion 311a. The holding arm 3a is positioned such that the second arm portion 312a and the contact portion 32 are located within the arrangement space 5 of the work holder 1a.

[0061] A pivot shaft 311Aa is formed at the base end of the holding arm 3a (the end opposite to the bent portion 310a of the first arm portion 311a), projecting upward (in the Y-axis direction as shown in the figure). This pivot shaft 311Aa is rotatably supported in a stop hole 223a formed in the upper cover 22a. The holding arm 3a also has a pressed portion 313a that bends and extends in the longitudinal direction of the first arm portion 311a so as to connect to the base end where the pivot shaft 311Aa is formed. A projection 313a-1 is formed on the side of the pressed portion 313a opposite to the pivot shaft 311Aa, which connects to the elastic member 421a described later (Figure 6A).

[0062] The operating mechanism 4a, provided within the cover 21a that constitutes the holder body 2a, operates the holding arm 3a so that the tip of the holding arm 3a (contact portion 32) moves between a first position (position in Figure 6A) where it approaches the center (central axis O) of the arrangement space 5 and a second position (position in Figure 6B) where it moves away from the center (central axis O) of the arrangement space 5.

[0063] The operating mechanism 4a has a ring-shaped cam member 41a (Figures 5 and 6A) having an annular disc shape. In its circumferential direction, this ring-shaped cam member 41a has sets of guide holes 411Aa and cam holes 411Ba, which are both substantially straight and elongated, and a relatively small-diameter stop hole 411Ca, which are formed at equal intervals from each other, corresponding to the mounting positions of the multiple holding arms 3a.

[0064] Furthermore, the operating mechanism 4a has an elastic member (for example, a coil spring) 421a (Figures 5 and 6A) that individually biases the tip portions (contact portions 32) of the five holding arms 3a toward a first position (position in Figure 6A). The elastic member 421a is not limited to a coil spring and may be other elastic members, such as other springs or rubber material.

[0065] Furthermore, the operating mechanism 4a has a fixing part 422a (Figure 5) that fixes the elastic member 421a and the upper cover 22a. The fixing part 422a has an L-shaped fixing member 422a-1 and a bolt 422a-2. As shown in Figure 6A, the fixing member 422a-1 has a protrusion 422a-11 and a small-diameter hole 422a-12. One end of the elastic member 421a is connected to the protrusion 313a-1 (Figure 6A) of the pressed part 313a, and the other end of the elastic member 421a is connected to the protrusion 422a-11 (Figure 6A) of the L-shaped fixing member 422a-1. Furthermore, a bolt 422a-2, which engages with a small-diameter hole 422a-12 (Figure 6A) formed in one side of the L-shaped fixing member 422a-1, engages with a stop hole 222a in the disc portion 225a of the upper cover 22a (Figure 5). Also, the other side of the fixing member 422a-1 that bends relative to the side in which the small-diameter hole 422a-12 is formed is positioned within the cam hole 411Ba of the ring-shaped cam member 41a (Figures 5 and 6A). A bolt 48a that engages with a stop hole 232a of the lower cover 23a engages with a hole (not shown) formed in the fixing member 422a-1 (Figure 5).

[0066] Furthermore, the operating mechanism 4a has a pressing member (pressing pin) 47a (Figures 5 and 6A) that engages with the stop hole 411Ca of the ring-shaped cam member 41a and presses one side of the pressed portion 313a. The operating mechanism 4a also has a guide pin 43a (Figures 5 and 6A) that is positioned within the guide hole 411Aa of the ring-shaped cam member 41a and engages with the upper cover 22a and the lower cover 23a. The upper end of the guide pin 43a is engaged with the stop hole 221a of the disc portion 225a of the upper cover 22a. The lower end of the guide pin 43a is engaged with the guide hole 411Aa, and its lower end is engaged with the stop hole 233a of the disc portion 234a of the lower cover 23a via a bolt 45a (Figure 5).

[0067] In this way, the guide pin 43a engages with the guide hole 411Aa of the ring-shaped cam member 41a, with one end connected to the upper cover 22a and the other end connected to the lower cover 23a, thereby guiding the movement of the ring-shaped cam member 41a along the holder body 2a. The length of the guide hole 411Aa restricts the rotational range of the ring-shaped cam member 41a.

[0068] Next, the operation of the holding arm 3a in the work holder 1a according to the second embodiment will be described mainly with reference to Figures 6A to 6C and Figure 7. When the work holder 1a is in an unoperated state (original state), as shown in Figures 6A and 7, the tip of the holding arm 3a (contact portion 32) is in a first position (position in Figure 6A) that is close to the center of the arrangement space 5. In this unoperated state, the pressing member (pressing pin) 47a engaged with the ring-shaped cam member 41a is in contact with the pressed portion 313a of the holding arm 3a, but no pressing force is applied to the pressed portion 313a.

[0069] With respect to the work holder 1a in that state, the operating projection 412 provided on the ring-shaped cam member 41a is gripped by an actuator or the like (not shown) and moved in the direction of the circumferential arrow T1. This causes the ring-shaped cam member 41a to rotate by a predetermined angle β in the direction of the circumferential arrow T1 from the position shown in Figure 6A (Figure 7) around the central axis O (Figure 6B). As the ring-shaped cam member 41 rotates in this way, the pressing member (pressing pin) 47a that engages with the ring-shaped cam member 41a applies a pressing force in the direction of the circumferential arrow T1 to the side surface of the pressed portion 313a that it contacts. The holding arm 3a, to which this pressing force is applied, rotates around the rotation axis 311Aa such that the first arm portion 311a faces radially outward. As a result, the work holder 1a is in an open state (standby state) as shown in Figure 6B, that is, the tip (contact portion 32) of the second arm portion 312a of the holding arm 3a is in a second position (position in Figure 6B) away from the center of the arrangement space 5. In this state, the tip (contact portion 32) of the holding arm 3a is biased toward its original first position (position in Figure 6A) by the elasticity of the elastic member 421a to which a pressing force is applied via the pressed portion 313a by the pressing member 47a.

[0070] In the second embodiment, when the ring-shaped cam member 41a is rotated by a predetermined angle β in the direction of the circumferential arrow T1 around the central axis O to the position shown in Figure 6B, the guide hole 411Aa rotates along the guide pin 43a that engages with the upper cover 22a and the lower cover 23a. As a result, the work holder 1a can stably rotate the ring-shaped cam member 41a in the direction of the circumferential arrow T1 within the holder body 2a.

[0071] While the work holder 1a is in the open state (standby state) as shown in Figure 6B, the position of the operating projection 412 is temporarily fixed by an actuator or the like. As a result, the ring-shaped cam member 41a holds the tip (contact portion 32) of the holding arm 3a in the second position (position in Figure 6B). In this state, the workpiece is placed in the placement space 5. Subsequently, when the temporary position fixing of the operating projection 412 by the actuator or the like is released, the ring-shaped cam member 41a rotates back to its original position (in the direction of arrow T2, opposite to the direction of arrow T1 in the circumferential direction) due to the elasticity of the elastic member 421a.

[0072] The rotation of the ring-shaped cam member 41a releases the pressing force applied to the pressed portion 313a by the pressing member (pressing pin) 47a, and the elastic biasing force in the direction of arrow T2 due to the elasticity of the elastic member 421a is applied to the pressed portion 313a. As a result, the ring-shaped cam member 41a releases the holding of the tip (contact portion 32) of the holding arm 3a at the second position (Figure 6B), and simultaneously moves this tip back to its original first position (position in Figure 6A).

[0073] In the work holder 1a according to the second embodiment, each of the five elastic members 421a individually biases the tip (contact portion 32) of the connected holding arm 3a toward the first position. As a result, the operation of the operating mechanism 4a, which comprises the five elastic members 421a and a ring-shaped cam member 41a that engages with them, causes the five holding arms 3a, which are distributed in the arrangement space 5, to rotate independently in accordance with the expansion and contraction of the elastic members 421a connected to the holding arms 3a.

[0074] Therefore, regardless of the shape of the outer edge of the workpiece to be held, as each of the five holding arms 3a moves from the second position (position in Figure 6B) back to the original first position (position in Figure 6A), each holding arm 3a independently rotates based on the elasticity of the elastic member 421a until it contacts the outer edge of the workpiece. As a result, in the workpiece holder 1a according to the second embodiment, all the holding arms 3a will hold the outer edge of the workpiece, regardless of the shape of the outer edge of the workpiece to be held. For example, in the example shown in Figure 6C, all of the tips (contact portions 32) of the five holding arms 3a contact the outer edge of an eyeglass lens 20, which is an example of a workpiece located in the arrangement space 5. In this case, the closer the contact position of the tip (contact portion 32) of the holding arm 3a to the eyeglass lens 20 is to the central axis O, the greater the elongation rate of the elastic member 421a connected to that holding arm 3a.

[0075] As described above, the work holder 1a according to the second embodiment is equipped with an elastic member 421a that individually biases the tip portions (contact portions 32) of the plurality of holding arms 3a toward a first position. As a result, in this work holder 1a, regardless of the shape of the outer peripheral edge of the workpiece to be held, the tip portions (contact portions 32) of all the holding arms 3a independently perform a rotational movement based on the elasticity of the elastic member 421a until they contact the outer peripheral edge of the workpiece located in the arrangement space 5, so that the workpiece can be stably held by all of these holding arms 3a. In other words, in this work holder 1a, regardless of the shape of the outer peripheral edge of the workpiece (for example, even if it is elliptical like an eyeglass lens 20), a uniform force can be applied around the workpiece, and distortion occurring in the workpiece can be suppressed, so the workpiece can be stably held.

[0076] In other words, according to the work holder 1a of the second embodiment, a single work holder 1a can accommodate workpieces having a wide variety of peripheral edge shapes, and it can suppress distortion in the workpiece by applying a uniform force to the surroundings when holding the workpiece.

[0077] When removing the workpiece held by the holding arm 3a from the workpiece holder 1a, the operating projection 412 is again gripped by an actuator or the like and moved in the direction of the circumferential arrow T1 to rotate the ring-shaped cam member 41a in the direction of arrow T1. This moves the tip (contact portion 32) of the second arm portion 312a toward the second position (position in Figure 6B), and the workpiece is removed from the holding arm 3a.

[0078] Although the first and second embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and any design changes, etc., that do not depart from the gist of the present invention are also included. Furthermore, the aforementioned examples can be combined by utilizing each other's technologies, as long as there are no particular contradictions or problems in their purpose and configuration.

[0079] Although the aforementioned holder bodies 2 and 2a are shaped to surround the arrangement space 5, the shape of the holder body does not need to surround the entire arrangement space 5 as shown in Figures 1, 2 and 5. It may be shaped to surround the arrangement space 5 while leaving a part of it open. In that case, the holder body may be provided with a C-shaped cam member (not shown) that surrounds the arrangement space 5 while leaving a part of it open, instead of the aforementioned ring-shaped cam members 41 and 41a.

[0080] 1, 1a: Work holder, 2, 2a: Holder body, 3, 3a: Holding arm, 4, 4a: Operating mechanism, 5: Arrangement space, 20: Eyeglass lens, 21, 21a: Cover, 22, 22a: Upper cover, 23, 23a: Lower cover, 32: Contact part (pin), 33: Flange part, 34: Cushioning member, 41, 41a: Ring-shaped cam member, 43, 43a: Guide pin, 45: Washer, 45a, 48a, 422a-2: Bolt, 47a: Pressing member (pressing pin), 221, 221a, 222, 222a, 223a, 232a, 233, 233a, 411C, 411Ca: Blind hole, 422a-12: Hole, 225, 225a, 234, 234a: Disc Part, 227A, 236: Inner circumferential side part, 227B: Space part, 231: Handle part, 313a-1, 422a-11: Protruding part, 226, 235: Outer circumferential side part, 310, 310a: Bending part, 311, 311a: First arm part, 311A, 311Aa: Rotating shaft, 312, 312a: Second arm part, 313: Engaging projection, 313a: Pressed portion, 411A, 411Ba: Cam hole portion, 411Aa, 411B: Guide hole portion, 411A-1, 411A-2: End portion, 412: Operating projection portion, 421, 421a: Elastic member, 422, 423: Engaging member, 422a: Fixing portion, 422a-1: Fixing member, O: Central axis, P: Rotation axis, T1, T2: Arrow

Claims

1. A workpiece holder for holding the outer edge of a workpiece, comprising: a holder body surrounding a space in which the workpiece is placed; a holding arm, partly disposed within the holder body, with its tip movable between a first position approaching the center of the space and a second position away from the center of the space; and an operating mechanism provided within the holder body for operating the holding arm so that its tip moves between the first and second positions, wherein a plurality of holding arms are distributed around the space, and their tips contact the outer edge of the workpiece at least three or more points to hold the workpiece.

2. The work holder according to claim 1, wherein the holder body has a cover that houses the operating mechanism, and the holding arm has a pivot axis that is pivotally supported by the cover.

3. The workpiece holder according to claim 1, wherein the holding arm has a contact portion extending in the thickness direction of the workpiece at its tip, and the contact portion is equipped with an anti-slip cushioning member that contacts the outer edge of the workpiece.

4. The work holder according to claim 1, wherein the operating mechanism is configured such that a ring-shaped cam member that rotates by a predetermined angle surrounds the arrangement space, and the tip moves between the first position and the second position by the rotation of the ring-shaped cam member.

5. The work holder according to claim 4, wherein the operating mechanism comprises an elastic member that individually biases the tip portions of a plurality of holding arms toward the first position, and the ring-shaped cam member holds the tip portions in the second position with rotation in one direction and releases the holding of the tip portions in the second position with rotation in the other direction.

6. The workpiece holder according to claim 1, wherein the thickness of the holder body is greater than the thickness of the workpiece to be held.

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