Lean presser for holding eyeglass lens and eyeglass lens processing apparatus having the same

A lens presser for holding an eyeglass lens includes: a base member which is to be attached to a distal end of a lens chucking shaft; an abutting member which has an abutting surface which is to be abutted on a rear refractive surface of the lens; a movable member to which the abutting member is to be attached; a circular-arc-shaped concave portion which is formed in one of the base member and the movable member and has a radius center of a circular arc on a central axis of the chucking shaft; and a circular-arc-shaped convex portion which is formed in the other of the base member and the movable member and is fitted into the concave portion so as to slide only in a direction of the circular arc. The movable member is tiltable with respect to the base member.

BACKGROUND OF THE INVENTION

The present invention relates to a lens presser for holding an eyeglass lens, which is used when the eyeglass lens is processed, and an eyeglass lens processing apparatus having the same.

In an eyeglass lens processing apparatus, an eyeglass lens is rotated while being held (chucked) by two lens chucking shafts, and a periphery of the lens is processed by a processing tool such as a grindstone so as to substantially coincide with a desired target lens shape. As a method of holding (chucking) a lens, there are two kinds of methods, optical-center chucking in which the lens is be held so as to conform (align) an optical center of the lens to a holding (rotation) axis of the lens, and boxing center chucking in which the lens is held so as to conform (align) a geometric center (boxing center) of the target lens shape, which is laid out in the lens, to the holding axis of the lens.

In the boxing center chucking, since a lens is held in a position deviated from the optical center, such a lens presser is proposed that can correspond to a curved surface of the rear refractive surface of a lens (refer to JP-A No. 2002-310146). The above lens presser is provided with a movable member to which an abutting member is attached. The movable member is tiltable (rotatable), centered on a position of a base member attached to a lens chucking shaft.

As shown inFIG. 10, another lens presser is proposed in which a bowl-shaped movable member903having an abutting portion901is attached to a curved surface of a base member905attached to a lens chucking shaft900R through a screw907.

In the former lens presser, however, the movable member does not move smoothly and a lens cannot be stably held, because the tilt (rotation) center of the movable member is present in the base member side. On the other hand, in the latter lens presser, the movable member is easily rotated with respect to the lens chucking shaft centered on the holding axis of a lens, and thus the lens cannot be stably held.

In processing a lens, processing water is used for cooling the processed portion of the lens and washing off ground waste of the lens. However, if minute chaff enters between the base member and the movable member of the lens presser, the movable member does not move smoothly. In this case, the base member and the movable member are separated so as to be cleaned, but it is not easy to separate them in the related lens presser.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a lens presser, which can stably hold a lens and in which a base member and a movable member can be easily separated, and an eyeglass lens processing apparatus having the same.

In order to solve the above object, the present invention is characterized by having the following arrangement.

(1) A lens presser for holding an eyeglass lens comprising:

a base member which is to be attached to a distal end of a lens chucking shaft;

an abutting member which has an abutting surface which is to be abutted on a rear refractive surface of the lens;

a movable member to which the abutting member is to be attached;

a circular-arc-shaped concave portion which is formed in one of the base member and the movable member and has a radius center of a circular arc on a central axis of the chucking shaft; and

a circular-arc-shaped convex portion which is formed in the other of the base member and the movable member and is fitted into the concave portion so as to slide only in a direction of the circular arc,

wherein the movable member is tiltable with respect to the base member.

(2) The lens presser according to (1), wherein the concave portion has the radius center of the circular arc in the vicinity of the abutting surface of the abutting member in a state where the base member, the movable member, and the abutting member are assembled.
(3) The lens presser according to (1), wherein the convex portion is fitted into the concave portion with a dovetail joint.
(4) The lens presser according to (1), further comprising a detachable restriction member which prevents the convex portion fitted into the concave portion from coming off.
(5) The lens presser according to (4), wherein the abutting member also serves as the restriction member.
(6) The lens presser according to (1), wherein the abutting surface of the abutting member is substantially elliptical.
(7) An eyeglass lens processing apparatus comprising a chucking shaft to which the lens presser according to (1) is attached.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.FIG. 1is a view showing a schematic configuration of a lens processing portion of an eyeglass lens processing apparatus according to an embodiment of the present invention.FIG. 2is a view showing a schematic configuration of a carriage portion700of the lens processing portion. The carriage portion700including a carriage700and its moving mechanism is mounted on a base10. A lens LE to be processed is held (chucked) and rotated by lens chucking shafts702L and702R, which are rotatably held by the carriage701, and is ground by a grindstone602. The grindstone602of the present embodiment includes a roughing grindstone602afor plastic, a roughing grindstone602bfor glass, and a bevel-finishing and plane-finishing grindstone602c. The grindstone602is rotated by a grindstone rotating motor606. A lens shape measuring portion500is provided at the back side (inner side) of the carriage portion700.

The chucking shafts701L and701R are held by the carriage701so that the central axis thereof is parallel to the central axis of rotation of the grindstone602. The carriage701is movable in a direction of the rotation central axis of the grindstone602(that is, a direction of the central axis of the chucking shafts702L and702R) (X-axis direction). Further, the carriage701is movable in a direction orthogonal to the X-axis direction (that is, a direction in which a distance between the central axis of the chucking shafts702L and702R and the rotation central axis of the grindstone602changes) (Y-axis direction).

The chucking shafts702L and702R are rotatably and coaxially held by left and right arms701L and701R, respectively, of the carriage701. A cup receiver350is attached to a distal end of the chucking shaft702L, and a lens presser300is attached to a distal end of the chucking shaft702R (refer toFIG. 3). A lens chucking motor710is fixed to the right arm701R. The rotation of the motor710is transmitted to a feed screw715via a pulley711attached to the rotating shaft of the motor701, a belt712and a pulley713attached to the feed screw715. Then, a feed nut714screwed to the feed screw715is moved in its axial direction, and the chucking shaft702R coupled with the nut714is moved in its axial direction. When the lens LE is processed, as shown inFIG. 3, a cup50that is a fixture is attached to the front refractive surface of the lens LE. A base of the cup50is mounted to the cup receiver350attached to the chucking shaft702L. Further, by driving the motor710, the chucking shaft702R is moved in a direction in which it approaches the chucking shaft702L, the lens presser300attached to the chucking shaft702R abuts on the rear refractive surface of the lens LE, and the lens LE is held (chucked) by the chucking shafts702L and702R.

A lens rotating motor722is fixed to the left arm701L. The rotation of the motor722is transmitted to the chucking shaft702L via a gear723attached to the rotating shaft of the motor722, a gear724and a gear721attached to the chucking shaft702L. Further, the rotation of the motor722is transmitted to the chucking shaft702R via a pulley726attached to the chucking shaft702L, a belt731a, a pulley703a, a rotating shaft728, a pulley703b, a belt731b, and a pulley733attached to the chucking shaft702R. Accordingly, the chucking shafts702L and702R are rotated synchronously, and the held (chucked) lens LE is rotated.

Next, the lens presser300will be described with reference toFIGS. 3 to 7. The lens presser300includes a base member310which is to be attached and fixed to the distal end of the chucking shaft702R, a movable member320which is to be tilt-adjustably (rotatably) attached to the base member310, and an abutting member330which is to be attached to the movable member302and has an abutting surface303awhich is to be abutted on the rear refractive surface of the lens LE.FIG. 4Ais a perspective view of the base member310, andFIG. 4Bis a side sectional view of the base member310.FIG. 5Ais a perspective view of the movable member320, andFIG. 5Bis a lateral view of the movable member320.FIG. 6Ais a perspective view of the abutting member330, andFIG. 6Bis a side sectional view of the abutting member330.FIG. 7is a sectional view taken along the line A-A ofFIG. 3.

The base member310is formed of metal such as stainless steel. A hole311into which the distal end of the chucking shaft702R is to be inserted is formed inside the base member310. Further, a screw hole312into which a screw for attaching and fixing the base member310to the chucking shaft702R is to be inserted is formed on the side surface of the base member310. A dovetail groove315as a circular-arc-shaped concave portion is formed on the side where the base member310is to be attached to the movable member320. The cross-section of the dovetail groove315, orthogonal to the longitudinal direction thereof, is dovetail-shaped, and the width W1of the cross-section is smaller than the width W2thereof (refer toFIG. 7). Further, a groove surface (inner surface)315aof the dovetail groove315is formed in a circular-arc shape whose radius R1is 10 mm and whose center is set to the center O on the central axis X01of the chucking shaft702R, and both outer surfaces315bof the dovetail groove315are formed in a circular-arc shape whose radius R2is 8.5 mm and whose the center is set to the center O. The center O is almost the same position as the abutting surface330aof the abutting member330when the lens presser300(base member310, the movable member, and the abutting member330) is assembled (refer toFIG. 3). Further, the groove surface315aof the dovetail groove315has a length L1of 16 mm in a direction orthogonal to the central axis X01.

The movable member320is formed of resin having a metallic characteristic and softness, such as Delrin made by du Pond Corporation. In the base member310side of the movable member320, a dovetail325as a circular-arc-shaped convex portion is formed, which is to be slidably fitted only in a circular arc direction of the dovetail groove315. Similar to the cross-section of the dovetail groove315, the cross-section of the dovetail325, orthogonal to the longitudinal direction thereof, is dovetail-shaped, and the width W1of the cross-section is smaller than the width W2thereof (refer toFIG. 7). The top surface325aof the dovetail325is formed in a circular arc shape whose radius r1is 9.9 mm and whose the center is set to the center O, and both outer surfaces323bof the dovetail325are formed in a circular arc shape whose radius r2is 8.5 mm and whose the center is set to the center O. The top surface325aof the dovetail325has a length L2of 19 mm in a direction orthogonal to the central axis X01. Four holes321are formed in the side where the movable member320is to be attached to the abutting member330. Further, a through-hole323is formed in the center of the movable member320.

The abutting member330is formed of elastic resin such as rubber. The abutting member330also serves as a restriction member which prevents the movable member320from coming off from the base member310(detailed descriptions will be made below). Four projections331which are to be respectively fitted into the holes321of the movable member320are formed in the movable member320side of the abutting member330. The shape of the abutting member330in a direction orthogonal to the central axis X01is substantially elliptical, and the abutting member330is to be attached to the movable member320so that the longitudinal direction of the elliptic shape coincides with a circular-arc direction of the dovetail325of the movable member320. The longitudinal length L3of the substantially elliptical abutting member330in a direction orthogonal to the central axis X01is 30 mm, and the short-side length of the substantially elliptical abutting member330in a direction orthogonal to the central axis X01is 17 mm. The substantially elliptic shape of the abutting surface330aof the abutting member330is almost the same as the substantial elliptic shape of the cup50.

A through-hole333is formed in the center of the abutting member330. Further, a hole335with a step, of which the diameter is larger than the through-hole333, is formed in the center of the abutting surface330aof the abutting member330. The holes335and333are set to a discharge port of air when the rear refractive surface of the lens LE abuts on the abutting surface330a, and the air is discharged outside through the hole323of the movable member320and the hole311of the base member310.

The lens presser300having such a construction is assembled as follows. First, the dovetail325of the movable member320is inserted and fitted into the dovetail groove315of the base member310so that the movable member320is attached to the base member310. Next, the projections331of the abutting member330are inserted and fitted into the holes331of the movable member320so that the abutting member330is attached to the movable member320. Since the longitudinal length L3of the abutting member330is larger than the length L1of the dovetail groove315and the length L2of the dovetail325, the movable member320does not come off from the base member310even though being tilted along the dovetail groove315. That is, the abutting member330functions as a restriction member which prevents the movable member320(dovetail325) from coming off from the base member310(dovetail groove315) in the circular arc direction. Moreover, the restriction member may be provided for exclusive use. For example, after the movable member320is attached to the base member310, the restriction member may be attached to either side of the dovetail325(if the movable member320is prevented from coming off in one end of the dovetail groove315, the restriction member is attached only on the end of the dovetail325in the other end side). Further, when the dovetail groove315is larger than the dovetail325, the restriction member may be attached to the dovetail groove315.

The abutting member330is set to be tiltable (rotatable) at about ±30° with respect to the base member310via the movable member320.

Holding of the lens LE by the lens presser300will be described.FIG. 8is a view showing an example of the layout of a target lens shape with respect to an unprocessed lens LE. OL represents the optical center of the lens LE, and OF represents the geometric center (boxing center) of the target lens shape FC. As a method in which the cup50is attached and fixed to the lens LE, there are two kinds of methods, optical center blocking in which the optical center OL is conformed (aligned) to the axis of the cup50, and boxing center blocking in which the geometric center OF is conformed (aligned) to the axis of the cup50. The cup50which has been optical-center-blocked is mounted on the cup receiver350, so that the lens LE is chucked at the optical center by the chucking shafts702L and702R (optical center chucking). The cup50which has been boxing center-blocked is mounted on the cup receiver350, so that the lens LE is chucked at the boxing center by the chucking shafts702L and702R (boxing center chucking). The boxing center blocking is used when the width of the target lens shape FC in the up and down direction is narrow or when the deviation of the boxing center OF with respect to the optical center OL is large. The cup50is attached and fixed to the lens LE by a well-known blocking apparatus. The left and right direction ofFIG. 8is a direction of the distance between the pupils of a wearer (a person who uses a pair of eyeglasses). The deviation of the boxing center OL with respect to the optical center OF is typically larger in the left and right direction than in the up and down direction.

When the cup50is boxing-center-blocked to the lens LE in which the target lens shape FC is laid out, the cup50is attached and fixed so that the longitudinal direction of the substantially-elliptical cup50coincides with the longitudinal direction (left and right direction) of the target lens shape FC. When the lens LE to which the cup50is fixed is held (chucked) by the chucking shafts702L and702R, the cup50is mounted an the cup receiver350so that the longitudinal direction of the cup50coincides with the longitudinal direction of the abutting member330(abutting surface330a). Further, as the chucking shaft702R is moved in a direction in which it approaches the chucking shaft702L, the lens LE is held (chucked). In the lens presser300, since the abutting member330is tiltable in the longitudinal direction via the movable member320, the abutting member330is tilted and abutted so as to correspond to a curved surface corresponding to the longitudinal direction of the target lens shape FC of the rear refractive surface of the lens LE.

Since the dovetail325is guided by the dovetail groove315so as to slide, the movement of the movable member320becomes smooth. Further, as the movable member320is tiltable with respect to the base member310and can be deformed by a chucking pressure due to the movement of the chucking shaft702R, the lens LE is can be stably held. Since the tilt width of the abutting member330is broadened, the abutting area onto the lens LE can be widely secured, and even a lens subjected to super-hydrophobic coating can be stably held.

Based on the target lens shape, the periphery of the lens LE is ground by the grindstone602. Moreover, the apparatus of the present embodiment is such an apparatus which processes a lens by moving the lens with respect to a grindstone. However, the apparatus may be such an apparatus which processes a lens by moving one grindstone or a plurality of grindstones.

When the movement of the movable member320with respect to the base member310is not smooth due to grinding waste (chaff) generated by processing the lens LE, the movable member320is removed from the base member310and is cleaned. That is, first, the projections331of the abutting member330are pulled off from the holes321of the movable member320so that the abutting member330is removed from the movable member320. Next, the dovetail325of the movable member320is taken out of the dovetail groove315of the base member310so that the movable member320is removed from the base member310.

In the above-described embodiment, various modifications can be made. For example, although the concave portion (dovetail groove) is formed in the base member310and the convex portion (dovetail) is formed in the movable member320in the above description, the concave portion may be formed in the movable member320and the convex portion may be formed in the base member310. Further, the respective cross-sections of the circular-arc-shaped concave portion and the circular-arc-shaped convex portion may be formed in a substantial T shape, as shown inFIG. 9. Further, the width W1of the respective cross-sections of the concave portion350and the convex portion351becomes smaller than the width W2, and the convex portion351is to be fitted into the concave portion350so as to slide only in the circular arc direction.