Abstract:
An eyeglass lens processing apparatus for processing a periphery of an eyeglass lens, includes: a lens rotating shaft which holds and rotates an eyeglass lens to be processed; an abrasive wheel rotating shaft movable between a retracted position and a processing position; a chamfering abrasive wheel which is attached to the abrasive wheel rotating shaft and which chamfers the lens while receiving a processing load from the lens during processing; a detecting unit which detects the load to the chamfering abrasive wheel; and a control unit which issues a control signal for relatively moving the lens and the chamfering abrasive wheel one from another to reduce the processing load if the detected processing load is higher than a predetermined first level and for continuing the chamfering, and which issues a control signal for ending the chamfering if the detected processing load over the entire periphery of the lens is lower than a predetermined second level.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to an eyeglass lens processing apparatus for processing a periphery (an edge) of an eyeglass lens.  
           [0002]    An eyeglass lens processing apparatus is available, which has a chamfering abrasive wheel for chamfering a lens corner portion after the lens periphery is subjected to processing with a rough abrasive wheel and a finishing abrasive wheel. An eyeglass lens processing apparatus having a grooving abrasive wheel is also proposed.  
           [0003]    In case of processing a lens narrow in vertical width, such as a half-eye lens, the related eyeglass lens processing apparatus does not execute processing if an abrasive wheel interferes with a lens holding member during chamfering process, or only executes limited chamfering to such a degree as to avoid the interference. For this reason, the related eyeglass lens processing apparatus suffers from a problem in that a minimal processing diameter of a lens, which can be subjected to chamfering process, is large.  
           [0004]    The related eyeglass lens processing apparatus controls an amount of chamfering by adjusting the number of rotation of the lens, and thus there are some cases that processing efficiency is not good.  
         SUMMARY OF THE INVENTION  
         [0005]    Accordingly, an object of the present invention is to provide an eyeglass lens processing apparatus, which can efficiently execute chamfering process and which can make a minimal processing diameter of a lens as small as possible.  
           [0006]    The present invention provides the followings:  
           [0007]    (1) An eyeglass lens processing apparatus for processing a periphery of an eyeglass lens, comprising:  
           [0008]    a lens rotating shaft which holds and rotates an eyeglass lens to be processed;  
           [0009]    an abrasive wheel rotating shaft movable between a retracted position and a processing position;  
           [0010]    a chamfering abrasive wheel which is attached to the abrasive wheel rotating shaft and which chamfers the lens while receiving a processing load from the lens during processing;  
           [0011]    a detecting unit which detects the load to the chamfering abrasive wheel; and  
           [0012]    a control unit which issues a control signal for relatively moving the lens and the chamfering abrasive wheel one from another to reduce the processing load if the detected processing load is higher than a predetermined first level and for continuing the chamfering, and which issues a control signal for ending the chamfering if the detected processing load over the entire periphery of the lens is lower than a predetermined second level.  
           [0013]    (2) The eyeglass lens processing apparatus according to (1), wherein the control unit issues a control signal for ending the chamfering if a predetermined time period is elapsed or the lens is rotated predetermined number of times even in a case where the detected processing load over the entire periphery of the lens is not lower than the predetermined second level.  
           [0014]    (3) The eyeglass lens processing apparatus according to (1), wherein the lens rotating shaft includes a first shaft having a cup holder to which a cup attached to the lens is to be attached, and a second shaft having a lens retainer to which a rubber member for abutting against the lens is fixed, and the first and second shafts are relatively moved one from another in a direction of a rotational axis thereof to clamp the lens therebetween.  
           [0015]    (4) The eyeglass lens processing apparatus according to (1), further comprising:  
           [0016]    a first moving unit having a motor, which relatively moves the lens rotating shaft and the abrasive wheel rotating shaft one from another to vary an axis-to-axis distance therebetween;  
           [0017]    a second moving unit having a motor, which relatively moves the lens rotating shaft and the abrasive wheel rotating shaft one from another in a direction of a rotational axis thereof; and  
           [0018]    wherein the control unit issues the control signal to at least one of the first and second moving unit to relatively move the lens and the chamfering abrasive wheel the one from the other.  
           [0019]    (5) The eyeglass lens processing apparatus according to (1), further comprising:  
           [0020]    a first rotating unit having a first motor, which rotates the lens wheel rotating shaft;  
           [0021]    a second rotating unit having a second motor, which rotates the abrasive wheel rotating shaft; and  
           [0022]    wherein the detecting unit detects a load electric current of at least one of the first and second motors.  
           [0023]    (6) The eyeglass lens processing apparatus according to (5), wherein the predetermined second level includes an electric current value not higher than the predetermined first level.  
           [0024]    (7) An eyeglass lens processing apparatus for processing a periphery of an eyeglass lens, comprising:  
           [0025]    a lens rotating shaft which holds and rotates an eyeglass lens to be processed;  
           [0026]    an abrasive wheel rotating shaft movable between a retracted position and a processing position;  
           [0027]    a chamfering abrasive wheel which is attached to the abrasive wheel rotating shaft and which chamfers the lens while receiving a processing load from the lens during processing;  
           [0028]    a detecting unit which detects the load to the chamfering abrasive wheel; and  
           [0029]    a control unit which issues a control signal for relatively moving the lens and the chamfering abrasive wheel one from another to reduce the processing load if the detected processing load is higher than a predetermined first level and for continuing the chamfering, and which issues a control signal for ending the chamfering if the detected processing load over the entire periphery of the lens is lower than a predetermined second level,  
           [0030]    wherein the control unit issues a control signal for ending the chamfering if a predetermined time period is elapsed or the lens is rotated predetermined number of times even in a case where the detected processing load over the entire periphery of the lens is not lower than the predetermined second level.  
           [0031]    The present disclosure relates to the subject matter contained in Japanese patent application No. 2000-134335 (filed on Apr. 28, 2000), which is expressly incorporated herein by reference in its entirety. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]    [0032]FIG. 1 is a diagram illustrating the external configuration of an eyeglass-lens processing apparatus in accordance with the invention;  
         [0033]    [0033]FIG. 2 is a perspective view illustrating the arrangement of a lens processing section disposed in a casing of a main body of the apparatus;  
         [0034]    [0034]FIG. 3 is a schematic diagram of essential portions of a carriage section;  
         [0035]    [0035]FIG. 4 is a view, taken from the direction of arrow E in FIG. 2, of the carriage section;  
         [0036]    [0036]FIG. 5 is a top view of a lens-shape measuring section;  
         [0037]    [0037]FIG. 6 is a left side elevational view of FIG. 5;  
         [0038]    [0038]FIG. 7 is a view illustrating essential portions of the right side surface shown in FIG. 5;  
         [0039]    [0039]FIG. 8 is a cross-sectional view taken along line F-F in FIG. 5;  
         [0040]    [0040]FIG. 9 is a diagram explaining the state of left-and-right movement of the lens-shape measuring section;  
         [0041]    [0041]FIG. 10 is a front elevational view of a chamfering and grooving mechanism section;  
         [0042]    [0042]FIG. 11 is a top plan view of the chamfering and grooving mechanism section;  
         [0043]    [0043]FIG. 12 is a left side elevational view of the chamfering and grooving mechanism section;  
         [0044]    [0044]FIG. 13 is a block diagram of a control system of the apparatus;  
         [0045]    [0045]FIG. 14 is an explanatory diagram showing a lens holding member to be attached to a lens chuck shaft.  
         [0046]    [0046]FIG. 15 is an explanatory diagram as to how to obtain a processing locus of chamfering process.  
         [0047]    [0047]FIG. 16 is a diagram showing an example in which a grooving abrasive wheel interferes with a lens retainer. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0048]    Hereafter, a description will be given of an embodiment of the invention.  
         [0049]    (1) Overall Construction  
         [0050]    [0050]FIG. 1 is a diagram illustrating the external configuration of an eyeglass-lens processing apparatus in accordance with the invention. An eyeglass-frame-shape measuring device  2  is incorporated in an upper right-hand rear portion of a main body  1  of the apparatus. As the frame-shape measuring device  2 , ones that disclosed in U.S. Pat. Nos. 5,228,242, 5,333,412, 5,347,762 (Re. 35,898) and so on, the assignee of which is the same as the present application, can be used. A switch panel section  410  having switches for operating the frame-shape measuring device  2  and a display  415  for displaying processing information and the like are disposed in front of the frame-shape measuring device  2 . Further, reference numeral  420  denotes a switch panel section having various switches for inputting processing conditions and the like and for giving instructions for processing, and numeral  402  denotes an openable window for a processing chamber.  
         [0051]    [0051]FIG. 2 is a perspective view illustrating the arrangement of a lens processing section disposed in the casing of the main body  1 . A carriage section  700  is mounted on a base  10 , and a subject lens LE clamped by a pair of lens chuck shafts of a carriage  701  is ground by a group of abrasive wheels  602  attached to a rotating shaft  601 . The group of abrasive wheels  602  include a rough abrasive wheel  602   a  for glass lenses, a rough abrasive wheel  602   b  for plastic lenses, and a finishing abrasive wheel  602   c  for beveling processing and flat processing. The rotating shaft  601  is rotatably attached to the base  10  by a spindle  603 . A pulley  604  is attached to an end of the rotating shaft  601 , and is linked through a belt  605  to a pulley  607  which is attached to a rotating shaft of an abrasive-wheel rotating motor  606 .  
         [0052]    A lens-shape measuring section  500  is provided in the rear of the carriage  701 . Further, a chamfering and grooving mechanism section  800  is provided in the front side.  
         [0053]    (2) Construction of Various Sections  
         [0054]    (A) Carriage Section  
         [0055]    Referring to FIGS. 2, 3, and  4 , a description will be given of the construction of the carriage section  700 . FIG. 3 is a schematic diagram of essential portions of the carriage section  700 , and FIG. 4 is a view, taken from the direction of arrow E in FIG. 2, of the carriage section  700 .  
         [0056]    The carriage  701  is capable of rotating the lens LE while chucking it with two lens chuck shafts (lens rotating shafts)  702 L and  702 R, and is rotatably slidable with respect to a carriage shaft  703  that is fixed to the base  10  and that extends in parallel to the abrasive-wheel rotating shaft  601 . Hereafter, a description will be given of a lens chuck mechanism and a lens rotating mechanism as well as an X-axis moving mechanism and a Y-axis moving mechanism of the carriage  701  by assuming that the direction in which the carriage  701  is moved in parallel to the abrasive-wheel rotating shaft  601  is the X axis, and the direction for changing the axis-to-axis distance between the chuck shafts ( 702 L,  702 R) and the abrasive-wheel rotating shaft  601  by the rotation of the carriage  701  is the Y axis.  
       Lens Chuck Mechanism and Lens Rotating Mechanism  
       [0057]    The chuck shaft  702 L and the chuck shaft  702 R are rotatably held coaxially by a left arm  701 L and a right arm  701 R, respectively, of the carriage  701 . A chucking motor  710  is fixed to the center of the upper surface of the right arm  701 R, and the rotation of a pulley  711  attached to a rotating shaft of the motor  710  rotates a feed screw  713 , which is rotatably held inside the right arm  701 R, by means of a belt  712 . A feed nut  714  is moved in the axial direction by the rotation of the feed screw  713 . As a result, the chuck shaft  702 R connected to the feed nut  714  can be moved in the axial direction, so that the lens LE is clamped by the chuck shafts  702 L and  702 R.  
         [0058]    A rotatable block  720  for attaching a motor, which is rotatable about the axis of the chuck shaft  702 L, is attached to a left-side end portion of the left arm  701 L, and the chuck shaft  702 L is passed through the block  720 , a gear  721  being secured to the left end of the chuck shaft  702 L. A pulse motor  722  for lens rotation is fixed to the block  720 , and as the motor  722  rotates the gear  721  through a gear  724 , the rotation of the motor  720  is transmitted to the chuck shaft  702 L. A pulley  726  is attached to the chuck shaft  702 L inside the left arm  701 L. The pulley  726  is linked by means of a timing belt  731   a  to a pulley  703   a  secured to a left end of a rotating shaft  728 , which is held rotatably in the rear of the carriage  701 . Further, a pulley  703   b  secured to a right end of the rotating shaft  728  is linked by means of a timing belt  731   b  to a pulley  733  which is attached to the chuck shaft  702 R in such a manner as to be slidable in the axial direction of the chuck shaft  702 R inside the right arm  701 R. By virtue of this arrangement, the chuck shaft  702 L and the chuck shaft  702 R are rotated synchronously.  
         [0059]    Lens holding members are attached respectively to the chuck shaft  702 L and the chuck shaft  702 R. As shown in FIG. 14, in case where a normal lens large in processing diameter is to be processed, a cup holder  750   a  is attached to the chuck shaft  702 L, and a lens retainer  751   a  to which a rubber member  752   a  is fixed is attached to the chuck shaft  702 R. Further, in order to hold the lens LE with the chuck shafts  702 L and  702 R, a cup  760   a  is preliminarily fixed to the lens LE.  
         [0060]    In case where a so-called half-eye lens is to be processed (i.e. a lens narrow in vertical width is to be processed), a cup holder  750   b  smaller in diameter than the cup holder  750   a  is attached to the chuck shaft  702 L, and a lens retainer  751   b  smaller in diameter than the lens retainer  751   a  is attached to the chuck shaft  702 R. Similarly to the lens retainer  751   a , a rubber member  752   b  is fixed to a leading end of the lens retainer  751   b  to be contacted with the lens LE. Further, as a cup fixed to the lens LE, a cup  760   b  smaller in diameter than the cup  760   a  is used.  
       X-axis Moving Mechanism and Y-axis Moving Mechanism of Carriage  
       [0061]    The carriage shaft  703  is provided with a movable arm  740  which is slidable in its axial direction so that the arm  740  is movable in the X-axis direction (in the axial direction of the shaft  703 ) together with the carriage  701 . Further, the arm  740  at its front portion is slidable on and along a guide shaft  741  that is secured to the base  10  in a parallel positional relation to the shaft  703 . A rack  743  extending in parallel to the shaft  703  is attached to a rear portion of the arm  740 , and this rack  743  meshes with a pinion  746  attached to a rotating shaft of a motor  745  for moving the carriage in the X-axis direction, the motor  745  being secured to the base  10 . By virtue of the above-described arrangement, the motor  745  is able to move the carriage  701  together with the arm  740  in the axial direction of the shaft  703  (in the X-axis direction).  
         [0062]    As shown in FIG. 3( b ), a swingable block  750  is attached to the arm  740  in such a manner as to be rotatable about the axis La which is in alignment with the rotational center of the abrasive wheels  602 . The distance from the center of the shaft  703  to the axis La and the distance from the center of the shaft  703  to the rotational center of the chuck shaft ( 702 L,  702 R) are set to be identical. A Y-axis moving motor  751  is attached to the swingable block  750 , and the rotation of the motor  751  is transmitted by means of a pulley  752  and a belt  753  to a female screw  755  held rotatably in the swingable block  750 . A feed screw  756  is inserted in a threaded portion of the female screw  755  in mesh therewith, and the feed screw  756  is moved vertically by the rotation of the female screw  755 .  
         [0063]    A guide block  760  which abuts against a lower end surface of the motor-attaching block  720  is fixed to an upper end of the feed screw  756 , and the guide block  760  moves along two guide shafts  758   a  and  758   b  implanted on the swingable block  750 . Accordingly, as the guide block  760  is vertically moved together with the feed screw  756  by the rotation of the motor  751 , it is possible to change the vertical position of the block  720  abutting against the guide block  760 . As a result, the vertical position of the carriage  701  attached to the block  720  can be also changed (namely, the carriage  701  rotates about the shaft  703  to change the axis-to-axis distance between the chuck shafts ( 702 L,  702 R) and the abrasive-wheel rotating shaft  601 ). A spring  762  is stretched between the left arm  701 L and the arm  740 , so that the carriage  701  is constantly urged downward to impart processing pressure onto the lens LE. Although the downward urging force acts on the carriage  701 , the downward movement of the carriage  701  is restricted such that the carriage  701  can only be lowered down to the position in which the block  720  abuts against the guide block  760 . A sensor  764  for detecting an end of processing is attached to the block  720 , and the sensor  764  detects the end of processing (ground state) by detecting the position of a sensor plate  765  attached to the guide block  760 .  
         [0064]    (B) Lens-Shape Measuring Section  
         [0065]    Referring to FIGS.  5  to  8 , a description will be given of the construction of the lens-shape measuring section  500 . FIG. 5 is a top view of the lens-shape measuring section, FIG. 6 is a left side elevational view of FIG. 5, and FIG. 7 is a view illustrating essential portions of the right side surface shown in FIG. 5. FIG. 8 is a cross-sectional view taken along line F-F in FIG. 5.  
         [0066]    A supporting block  501  is provided uprightly on the base  10 . A sliding base  510  is held on the supporting block  501  in such a manner as to be slidable in the left-and-right direction (in a direction parallel to the chuck shafts) by means of a pair of upper and lower guide rail portions  502   a  and  502   b  juxtaposed vertically. A forwardly extending side plate  510   a  is formed integrally at a left end of the sliding base  510 , and a shaft  511  having a parallel positional relation to the chuck shafts  702 L and  702 R is rotatably attached to the side plate  510   a . A feeler arm  514  having a feeler  515  for measuring the lens rear surface is secured to a right end portion of the shaft  511 , while a feeler arm  516  having a feeler  517  for measuring the lens front surface is secured to the shaft  511  at a position close to its center. Both the feeler  515  and the feeler  517  have a hollow cylindrical shape, a distal end portion of each of the feelers is obliquely cut as shown in FIG. 5, and the obliquely cut tip comes into contact with the rear surface or front surface of the lens LE. Contact points of the feeler  515  and the feeler  517  are opposed to each other, and the interval there between is arranged to be constant. Incidentally, the axis Lb connecting the contact point of the feeler  515  and the contact point of the feeler  517  is in a predetermined parallel positional relation to the axis of the chuck shafts ( 702 L,  702 R) in the state of measurement shown in FIG. 5. Further, the feeler  515  has a slightly longer hollow cylindrical portion, and measurement is effected by causing its side surface to abut against an edge surface of the lens LE during the measurement of the outside diameter of the lens LE.  
         [0067]    A small gear  520  is fixed to a proximal portion of the shaft  511 , and a large gear  521  which is rotatably provided on the side plate  510   a  is in mesh with the small gear  520 . A spring  523  is stretched between the large gear  521  and a lower portion of the side plate  510   a , so that the large gear  521  is constantly pulled in the direction of rotating clockwise in FIG. 7 by the spring  523 . Namely, the arms  514  and  516  are urged so as to rotate downward by means of the small gear  520 .  
         [0068]    A slot  503  is formed in the side plate  510   a , and a pin  527  which is eccentrically secured to the large gear  521  is passed through the slot  503 . A first moving plate  528  for rotating the large gear  521  is attached to the pin  527 . An elongated hole  528   a  is formed substantially in the center of the first moving plate  528 , and a fixed pin  529  secured to the side plate  510   a  is engaged in the elongated hole  528   a.    
         [0069]    Further, a motor  531  for arm rotation is attached to a rear plate  501   a  extending in the rear of the supporting block  501 , and an eccentric pin  533  at a position eccentric from a rotating shaft of the motor  531  is attached to a rotating member  532  provided on a rotating shaft of the motor  531 . A second moving plate  535  for moving the first moving plate  528  in the back-and-forth direction (in the left-and-right direction in FIG. 6) is attached to the eccentric pin  533 . An elongated hole  535   a  is formed substantially in the center of the second moving plate  535 , and a fixed pin  537  which is fixed to the rear plate  501   a  is engaged in the elongated hole  535   a . A roller  538  is rotatably attached to an end portion of the second moving plate  535 .  
         [0070]    When the eccentric pin  533  is rotated clockwise from the state shown in FIG. 6 by the rotation of the motor  531 , the second moving plate  535  moves forward (rightward in FIG. 6) by being guided by the fixed pin  537  and the elongated hole  535   a . Since the roller  538  abuts against the end face of the first moving plate  528 , the roller  538  moves the first moving plate  528  in the forward direction as well owing to the movement of the second moving plate  535 . As a result of this movement, the first moving plate  528  rotates the large gear  521  by means of the pin  527 . The rotation of the large gear  521 , in turn, causes the feeler arms  514  and  516  attached to the shaft  511  to retreat to an upright state. The driving by the motor  531  to this retreated position is determined as an unillustrated micro switch detects the rotated position of the rotating member  532 .  
         [0071]    If the motor  531  is reversely rotated, the second moving plate  535  is pulled back, the large gear  521  is rotated by being pulled by the spring  523 , and the feeler arms  514  and  516  are inclined toward the front side. The rotation of the large gear  521  is limited as the pin  527  comes into contact with an end surface of the slot  503  formed in the side plate  510   a , thereby determining the measurement positions of the feeler arms  514  and  516 . The rotation of the feeler arms  514  and  516  up to this measurement positions is detected as the position of a sensor plate  525  attached to the large gear  521  is detected by a sensor  524  attached to the side plate  510   a , as shown in FIG. 7.  
         [0072]    Referring to FIGS. 8 and 9, a description will be given of a left-and-right moving mechanism of the sliding base  510  (feeler arms  514 ,  515 ). FIG. 9 is a diagram illustrating the state of left-and-right movement.  
         [0073]    An opening  510   b  is formed in the sliding base  510 , and a rack  540  is provided at a lower end of the opening  510   b . The rack  540  meshes with a pinion  543  of an encoder  542  fixed to the supporting block  501 , and the encoder  542  detects the direction of the left-and-right movement and the amount of movement of the sliding base  510 . A chevron-shaped driving plate  551  and an inverse chevron-shaped driving plate  553  are attached to a wall surface of the supporting block  501 , which is exposed through the opening  510   b  in the sliding base  510 , in such a manner as to be rotatable about a shaft  552  and a shaft  554 , respectively. A spring  555  having urging forces in the directions in which the driving plate  551  and the driving plate  553  approach each other is stretched between the two driving plates  551  and  553 . Further, a limiting pin  557  is embedded in the wall surface of the supporting block  501 , and when an external force is not acting upon the sliding base  510 , both an upper end face  551   a  of the driving plate  551  and an upper end face  553   a  of the driving plate  553  are in a state of abutting against the limiting pin  557 , and this limiting pin  557  serves as an origin of the left- and rightward movement.  
         [0074]    Meanwhile, a guide pin  560  is secured to an upper portion of the sliding base  510  at a position between the upper end face  551   a  of the driving plate  551  and the upper end face  553   a  of the driving plate  553 . When a rightwardly moving force acts upon the sliding base  510 , as shown in FIG. 9( a ), the guide pin  560  abuts against the upper end face  553   a  of the driving plate  553 , causing the driving plate  553  to be tilted rightward. At this time, since the driving plate  551  is fixed by the limiting pin  557 , the sliding base  510  is urged in the direction of being returned to the origin of left- and rightward movement (in the leftward direction) by the spring  555 . On the other hand, when a leftwardly moving force acts upon the sliding base  510 , as shown in FIG. 9( b ), the guide pin  560  abuts against the upper end face  551   a  of the driving plate  551 , and the driving plate  551  is tilted leftward, but the driving plate  553  is fixed by the limiting pin  557 . Accordingly, the sliding base  510  this time is urged in the direction of being returned to the origin of left- and rightward movement (in the rightward direction) by the spring  555 . From such movement of the sliding base  510 , the amount of movement of the feeler  515  in contact with the lens rear surface and the feeler  517  in contact with the lens front surface (the amount of axial movement of the chuck shafts) is detected by a single encoder  542 .  
         [0075]    It should be noted that, in FIG. 5, reference numeral  50  denotes a waterproof cover, and only the shaft  511 , the feeler arms  514  and  516 , and the feelers  515  and  517  are exposed in the waterproof cover  50 . Numeral  51  denotes a sealant for sealing the gap between the waterproof cover  50  and the shaft  511 . Although a coolant is jetted out from an unillustrated nozzle during processing, since the lens-shape measuring section  500  is disposed in the rear of the processing chamber and by virtue of the above-described arrangement, it is possible to provide waterproofing for the electrical components and moving mechanism of the lens-shape measuring section  500  by merely providing shielding for the shaft  511  exposed in the waterproof cover  50 , and the waterproofing structure is thus simplified.  
         [0076]    (C) Chamfering and Grooving Mechanism Section  
         [0077]    Referring to FIGS.  10  to  12 , a description will be given of the construction of the chamfering and grooving mechanism section  800 . FIG. 10 is a front elevational view of the chamfering and grooving mechanism section  800 ; FIG. 11 is a top view; and FIG. 12 is a left side elevational view.  
         [0078]    A fixed plate  802  for attaching the various members is fixed to a supporting block  801  fixed to the base  10 . A pulse motor  805  for rotating an arm  820  (which will be described later) to move an abrasive wheel section  840  to a processing position and a retreated position is fixed on an upper left-hand side of the fixed plate  802  by four column spacers  806 . A holding member  811  for rotatably holding an arm rotating member  810  is attached to a central portion of the fixed plate  802 , and a large gear  813  is secured to the arm rotating member  810  extending to the left-hand side of the fixed plate  802 . A gear  807  is attached to a rotating shaft of the motor  805 , and the rotation of the gear  807  by the motor  805  is transmitted to the large gear  813  through an idler gear  815 , thereby rotating the arm  820  attached to the arm rotating member  810 .  
         [0079]    In addition, an abrasive-wheel rotating motor  821  is secured to a rear (left-hand side in FIG. 10) of the large gear  813 , and the motor  821  rotates together with the large gear  813 . A rotating shaft of the motor  821  is connected to a shaft  823  which is rotatably held inside the arm rotating member  810 , and a pulley  824  is attached to the other end of the shaft  823  extending to the interior of the arm  820 . Further, a holding member  831  for rotatably holding an abrasive-wheel rotating shaft  830  is attached to a distal end of the arm  820 , and a pulley  832  is attached to a left end (left-hand side in FIG. 11) of the abrasive-wheel rotating shaft  830 . The pulley  832  is connected to the pulley  824  by a belt  835 , so that the rotation of the motor  821  is transmitted to the abrasive-wheel rotating shaft  830 .  
         [0080]    The abrasive wheel section  840  is mounted on a right end of the abrasive-wheel rotating shaft  830 . The abrasive wheel section  840  is so constructed that a chamfering abrasive wheel  840   a  for a lens rear surface, a chamfering abrasive wheel  840   b  for a lens front surface, and a grooving abrasive wheel  840   c  provided between the two chamfering abrasive wheels  840   a  and  840   b  are integrally formed. The diameter of the grooving abrasive wheel  840   c  is about 30 mm, and the chamfering abrasive wheels  840   a  and  840   b  on both sides have processing slanting surfaces such that their diameters become gradually smaller toward their outward sides with the grooving abrasive wheel  840   c  as the center. (The diameter of the grooving abrasive wheel  840   c  is larger than the outmost diameter of each of the chamfering abrasive wheels  840   a  and  840   b .)  
         [0081]    It should be noted that the abrasive-wheel rotating shaft  830  is disposed in such a manner as to be inclined about 8 degrees with respect to the axial direction of the chuck shafts  702 L and  702 R, so that the groove can be easily formed along the lens curve by the grooving abrasive wheel  840   c . Additionally, the slanting surface of the chamfering abrasive wheel  840   a  and the slanting surface of the chamfering abrasive wheel  840   b  are so designed that the chamfering angles for the edge corners of the lens LE chucked by the chuck shafts  702 L and  702 R are respectively set to 55 degrees and 40 degrees.  
         [0082]    A block  850  is attached to this side on the left-hand side (this side on the left-hand side in FIG. 10) of the fixed plate  802 , and a ball plunger  851  having a spring  851   a  is provided inside the block  850 . Further, a limiting plate  853  which is brought into contact with a ball  851   b  of the ball plunger  851  is fixed to the large gear  813 . At the time of starting the grooving or chamfering, the arm  820  is rotated together with the large gear  813  by the rotation of the motor  805 , so that the abrasive wheel section  840  is placed at the processing position shown in FIG. 12. At this time, the limiting plate  853  is brought to a position for abutment against the ball  851   b.    
         [0083]    A sensor  855  for detecting the origin of the processing position is fixed below the block  850 . As the sensor  855  detects the light-shielded state of a sensor plate  856  attached to the large gear  813  so as to detect the origin of the processing position of the abrasive wheel section  840 , i.e., the position where the limiting plate  853  abuts against the ball  851   b  without application of the urging force due to the ball plunger  851 . This information on the origin of the processing position is used during calibration for defining the distance between the abrasive wheel section  840  and the chuck shafts  702 R and  702 L.  
         [0084]    Further, a sensor  858  for detecting the retreated position is fixed on an upper side of the block  850 . As the sensor  858  detects a sensor plate  859  attached to the large gear  813 , the sensor  858  detects the retreated position of the abrasive wheel section  840  which is rotated together with the arm  820  in the direction of arrow  846 . The retreated position of the abrasive wheel section  840  is set at a position offset rightwardly from a vertical direction in FIG. 12.  
         [0085]    Next, referring to the control block diagram shown in FIG. 13, a description will be given of the operation of the apparatus having the above-described construction. Here, a description will be given of the case in which grooving processing and chamfering processing are performed.  
         [0086]    The shape of an eyeglass frame (or template) for fitting the lens LE is measured by the frame-shape measuring device  2 , and the measured target lens shape data is inputted to a data memory  161  by pressing a switch  421 . The target lens shape based on the target lens shape data is graphically displayed on the display  415 , under which condition the processing conditions can be inputted. By operating switches on the switch panel section  410 , the operator inputs necessary layout data such as the PD of the wearer, the height of the optical center, and the like. Further, the operator inputs the material of the lens LE to be processed and the processing mode. In the case where grooving processing is to be effected, the mode for grooving processing is selected by a switch  423  for processing-mode selection. In the case where chamfering is to be effected, a switch  425  is operated to select the chamfering mode. Although the size of chamfering (the chamfering amount) for each of the lens front surface side and the lens rear surface side is stored in a memory  162  as a set value, in the case where the set value of the chamfering amount is to be changed, a menu screen can be opened by switch operation to the switch panel section  410  to change the contents preliminarily set.  
         [0087]    Upon completion of the necessary entry, the lens LE is chucked by the chuck shaft  702 L and the chuck shaft  702 R. In the case where the half-eye lens is to be processed, the cup holder  750   b  and the lens retainer  751   b  are preliminarily attached to chuck shafts  702 L and  702 R, respectively. Further, the cup  760   b  attached to the lens LE is mounted to the cup holder  750   b , and then the lens LE chucked.  
         [0088]    After the lens LE is completely chucked, the start switch  424  is pressed to operate the apparatus. On the basis of the inputted target lens shape data and layout data, a main control unit  160  obtains radius vector information (rδn, rθn) (n=1, 2, . . . , N) with the processing center as the center, determines processing correction information from positional information on a contact point where the radius vector abuts against the abrasive wheel surface (refer to Re. 35,898 (U.S. Pat. No. 5,347,762)), and stores it in the memory  161 .  
         [0089]    Subsequently, the main control unit  160  executes the lens shape measurement by using the lens-shape measuring section  500  in accordance with a processing sequence program. The main control unit  160  drives the motor  531  to rotate the shaft  511 , causing the feeler arms  514  and  516  to be positioned to the measuring position from the retreated position. On the basis of the radius vector data (rσn, rθn), the main control unit  160  vertically moves the carriage  701  so as to change the distance between the axis of the chuck shafts ( 702 L,  702 R) and the axis Lb connecting the feeler  515  and the feeler  517 , and causes the chucked lens LE to be located between the feeler  515  and the feeler  517 , as shown in FIG. 5. Subsequently, the carriage  701  is moved by a predetermined amount toward the feeler  517  side by driving the motor  745  so as to cause the feeler  517  to abut against the front-side refracting surface of the lens LE. The initial measuring position of the lens LE on the feeler  517  side is at a substantially intermediate position in the leftward moving range of the sliding base  510 , and a force is constantly applied to the feeler  517  by the spring  555  such that the feeler  517  abuts against the front-side refracting surface of the lens LE.  
         [0090]    In the state in which the feeler  517  abuts against the front-side refracting surface, the lens LE is rotated by the motor  722 , and the carriage  701  is vertically moved by driving the motor  751  on the basis of the radius vector information, i.e. the processing shape data. In conjunction with such movement and rotation of the lens LE, the feeler  517  moves in the left-and-right direction along the shape of the lens front surface. The amount of this movement is detected by the encoder  542 , and the shape of the front-side refracting surface of the lens LE (the path of the front-side edge position) after finishing processing is measured.  
         [0091]    In the case where the rear-side refracting surface of the lens LE is to be measured, the main control unit  160  rightwardly moves the carriage  701 , and causes the feeler  515  to abut against the rear-side refracting surface of the lens LE to change over the measuring surface. The initial measuring position of rear-side measurement is similarly at a substantially intermediate position in the rightward moving range of the sliding base  510 , and a force is constantly applied to the feeler  515  such that the feeler  515  abuts against the rear-side refracting surface of the lens LE. Subsequently, while causing the lens LE to undergo one revolution, the shape of the rear-side refracting surface (the path of the rear-side edge position) of the lens LE after the finishing processing is measured from the amount of movement of the feeler  515  in the same way as in the measurement of the front-side refracting surface. When the shape of the front-side refracting surface and the shape of the rear-side refracting surface of the lens LE can be obtained, edge thickness information can be obtained from the two items of the information. After completion of the lens shape measurement, the main control unit  160  drives the motor  531  to retreat the feeler arms  514  and  516 .  
         [0092]    The measurement of edge position for each of the front surface side and the rear surface side of the lens LE is executed at different positions with respect to the radius vector (i.e. the edge position at the outermost diameter, and the edge position inner than the former edge position), and the information on these edge positions is used for calculating the chamfering amount.  
         [0093]    Upon completion of the measurement of the lens shape, the main control unit  160  executes the processing of the lens LE in accordance with the input data of the processing conditions. In a case where the lens LE is a plastic, the main control unit  160  moves the carriage  701  by means of the motor  745  so that the lens LE is brought over the rough abrasive wheel  602   b , and vertically moves the carriage  701  on the basis of the processing correction information to perform rough processing. Next, the lens LE is moved to the planar portion of the finishing abrasive wheel  602   c , and the carriage  701  is vertically moved in the similar fashion to perform finish processing.  
         [0094]    Upon completion of finish processing, the operation then proceeds to grooving processing by the chamfering and grooving mechanism section  800 . After raising the carriage  701 , the main control unit  160  rotates the motor  805  a predetermined number of pulses so that the abrasive wheel section  840  placed at the retreated position comes to the processing position. Subsequently, as the carriage  701  is moved vertically and in the axial direction of the chuck shaft, the lens LE is positioned on the grooving abrasive wheel  840   c  which is rotated by the motor  821 , and processing is effected by controlling the movement of the carriage  701  on the basis of grooving processing data.  
         [0095]    The grooving processing data is determined in advance by the main control unit  160  from the radius vector information and the measured results of the lens shape. The data for vertically moving the carriage  701  is obtained by first determining the distance between the abrasive wheel  840   c  and the lens chuck shaft relative to the angle of lens rotation from the estimated radius vector information (rσn, rθn) and the diameter of the abrasive wheel  840   c  in the same way as for the group of abrasive wheels  602 , and then by incorporating information on the groove depth into it. In addition, as for the data on the groove position in the axial direction of the chuck shaft, since the edge thickness can be known from the shape of the front-side refracting surface and the shape of the rear-side refracting surface based on the measured data on the lens shape, the data on the groove position in the axial direction of the chuck shaft can be determined on the basis of this edge thickness in a procedure similar to that for determining the beveling position. For example, in addition to a method in which the lens edge thickness is divided at a certain ratio, it is possible to adopt various methods including one in which the groove position is offset by a fixed amount from the edge position of the lens front surface toward the rear surface, and is made to extend along the front surface curve.  
         [0096]    The grooving processing is effected while the lens LE is being caused to abut against the abrasive wheel  840   c  by the vertical movement of the carriage  701 . During the processing, the abrasive wheel  840   c  escapes from the origin of the processing position in the direction of arrow  845  in FIG. 12, but since a load is being applied to the abrasive wheel section  840  by the ball plunger  851 , the lens LE is gradually ground. Whether or not the grooving processing has been effected down to a predetermined depth is monitored by the sensor  858 , and the lens rotation is carried out until the completion of the processing of the entire periphery is detected.  
         [0097]    Upon completion of the grooving processing, the main control unit  160  effects chamfering by controlling the movement of the carriage  701  on the basis of the chamfering data.  
         [0098]    A description will be given of the calculation of the processing data at the time of chamfering, i.e. the calculation of the chamfering processing path. When chamfering is provided for the rear surface side and the front surface side of the lens LE, the respective processing data are calculated. A description will be given herein by citing as an example the case of the rear surface side of the lens LE.  
         [0099]    A maximum value of L is determined by substituting the radius vector information (rσn, rθn) (n=1, 2, . . . , N) into the formula given below. R represents the radius of the chamfering abrasive wheel  840   a  at the position where an edge of the rear surface of the lens abuts (e.g., an intermediate position of the abrasive wheel surface), and L represents the distance between the center of rotation of the abrasive wheel and the processing center of the lens LE. 
           L=rσn· cos  rθn+[R   2 −( rσn ·sin  rθn ) 2 ] ½ ( n= 1, 2, 3 , . . . , N )  [Formula 1] 
         [0100]    Next, the radius vector information (rσn, rθn) is rotated by a very small arbitrary unit angle about the processing center, and a maximum value of L at that time is determined in the same way as described above. This rotational angle is set as ξi (i=1, 2, . . . , N). By performing this calculation over the entire periphery, chamfering correction information in the radius vector direction can be obtained as (ξi, Li, Θi) in which a maximum value of L at the respective ξi is set as Li, and rθn at that time is set as Θi.  
         [0101]    The processing information in the axial direction of the lens chuck shaft for chamfering the rear surface side of the lens LE is obtained, as shown in FIG. 15, such that the path of a processing point Q is obtained based on an inclination angle of the lens rear surface (i.e. an inclination angle of a linear line L 1  connecting points P 1  and P 2 ), which is obtained from the edge position information on the two points P 1  and P 1  obtained through the lens shape measurement, a chamfering amount d and an inclination angle f of the chamfering abrasive wheel. The method of obtaining the chamfering processing path is basically the same as that disclosed in commonly assigned U.S. Pat. No. 6,062,947, and thus as to the details of this method, reference should be made on this patent.  
         [0102]    During chamfering processing, the main control unit  160  rotates the lens LE while controlling the vertical movement and lateral (right-and-left) movement of the carriage  701  based on the chamfering processing data, so that the lens LE is brought into contact with the abrasive wheel  840   a  of the abrasive wheel section  840  disposed at the processing position, thereby executing the chamfering processing.  
         [0103]    Here, in the case where the lens LE is a half-eye lens, the abrasive wheel  840   c  abuts against the rubber member  752   c  of the lens retainer  751   b  attached to the chuck shaft  702 R side when a portion of the lens LE, not having sufficient processing diameter, is processed (see FIG. 16). Since the abrasive wheel  840   c  is a diamond abrasive wheel, the abrasive wheel  840   c  can grind the lens retaining member such as the rubber member  752   b  and the like. If the abrasive wheel  840   c  contacts and grounds the rubber member  752   b , then a rotational load larger than that in a normal processing is applied to the motor  821  rotating the abrasive wheel section  840 . An electric current detecting section  165  is connected to the motor  821 , and the output from the detecting section  165  is inputted to the control unit  160 . The control unit  160  always monitors the load electric current of the motor  821  through the electric current detecting section  165 , and if the load electric current of the motor  821  exceeds a predetermined reference value I 1  higher than that in a normal chamfering processing (for example, the load electric current in the normal chamfering processing is about 2.0 A, whereas the predetermined reference value I 1  used to judge the application of the large rotational load is 2.5 A), the judgment is made that the processing load is applied to the abrasive wheel section  840 , upon which the carriage  701  is upwardly moved through drive control of the motor  701  so that the lens LE escapes from the abrasive wheel section  840 . The escape distance in this operation is set to about 0.5 mm, and the time for escape is set to be 3.6 degrees ({fraction (1/100)} rotation) in terms of rotation angle of the lens LE. The rotation angle of the lens LE is controlled based on the drive pulses of the motor  722 .  
         [0104]    After the lens LE is rotated 3.6 degrees, the control unit  160  downwardly moves the carriage  701  again in accordance with the chamfering processing data, and repeats these operations until the load electric current of the motor  821  falls within the reference value I 1 . With this processing, the lens having a small processing diameter, such as the half-eye lens, can be subjected to the chamfering processing as much as possible. That is, a range that the processing is applicable can be enlarged.  
         [0105]    Even in the case of a lens having such a sufficient processing diameter that the chamfering can be applied to the entire periphery of the lens, the control unit  160  monitors the load electric current of the motor  821 , and if the predetermined reference value I 1  is exceeded, the carriage  701  is moved in such a direction as to escape from the abrasive wheel section  840  during the predetermined lens rotation angle, and the chamfering processing is carried out in the state that the load electric current is lower than the reference value I 1 , similarly to the former case. The movement of the carriage  701  is controlled in accordance with the chamfering processing data, and if it is confirmed that the load electric current of the motor  821  over the entire periphery of the lens LE is lower than a reference value I 2  set to be lower than the reference value I 1  (the reference value I 2  may be set to be equal to the reference value I 1 ), the chamfering processing is completed. The processing is completed when lens LE is rotated at three or four times, even if the chamfering amount is set to be 1 mm. By way of the monitoring of the rotation state of the abrasive wheel section  840  and the controlling of the movement of the carriage  701  by the control unit  160 , the efficient processing can be realized using the performance of the abrasive wheel effectively while balancing the rotational load on the motor  821  with the processing amount appropriately.  
         [0106]    On the other hand, in the case of the half-eye lens small in processing diameter, the interference of the abrasive wheel  840   c  with the lens retainer  751   b  side at a portion of the lens LE as mentioned above may cause the load electric current of the motor  821  not to be lower than the reference value I 2  (or the reference value I 1 ) over the entire lens periphery even if the lens LE is rotated several times. To cope with this, the control unit  160  completes the chamfering processing if the lens LE is rotated, for example, five times. The number of rotation of the lens LE for judgment of the processing completion can be determined in relation to a maximum number of rotation of the lens LE by which the entire periphery of the lens LE can be chamfered. The number of rotation of the lens LE can be known based on the drive pulses of the motor  722 .  
         [0107]    In addition, as to the method of detecting the processing load on the chamfering abrasive wheel during chamfering processing, not only a method in which an electric current of an abrasive wheel rotating motor is directly detected as mentioned above, but also a method in which the load is detected based on variation in electric current of a motor rotating the lens LE, can be employed. Alternatively, the rotation state of the abrasive wheel side can be detected optically (see U.S. Pat. No. 6,123,604).  
         [0108]    The description has been given of the case that the chamfering is effected on the lens rear surface side. This is also applied to the case of the lens front surface, such that the load of the motor  821  when the abrasive wheel  840   c  abuts against the cup holder  750   b  and the like is detected, and the carriage  701  is similarly controlled to be moved in the direction away from the abrasive wheel section  840 . Further, such an arrangement may be employed that the abrasive wheel rotation shaft  830  side is relatively moved. Moreover, the component, i.e. the carriage  701  or the abrasive wheel rotation shaft  830  side, may be moved in the direction of the rotation axis.  
         [0109]    The apparatus of this embodiment is arranged such that the grooving abrasive wheel  840   c  is coaxially provided with respect to the chamfering abrasive wheels  840   a  and  840   b . However, even in the case where the abrasive wheel  840   c  is not provided, the outmost diameter portion of the abrasive wheel  840   a ,  840   b  may abut against the cup holder  750   b , the lens retainer  751   b  or the like if the processing is carried out on a lens portion not having the sufficient processing diameter. Accordingly, the similar control for chamfering processing can be applied also to this case. Further, the similar control can be applied to a type in which the chamfering abrasive wheel is provided coaxially with respect to the rough abrasive wheel  602   a  and the like. The chamfering abrasive wheel  840   a ,  840   b  is constructed also as a diamond abrasive wheel, and thus is not substantially influenced by the lens holding member. Since the lens holding member such as the lens retainer  751   b  and the like is of a supply replaceable with a new one, and therefore the damaged lens holding member can be easily replaced with a new one.  
         [0110]    As described above, according to the present invention, a processing diameter of a lens to be chamfered can be made as small as possible, thereby enlarging a range in which the chamfering processing can be applied. Further, the lens processing can be executed efficiently.