Abstract:
An eyeglass lens grinding apparatus for grinding a periphery of a lens. A processing device has abrasive wheels, and processes the lens while depressing the lens onto at least one of the abrasive wheels rotatingly driven by an abrasive wheel rotating motor. The lens is fixedly mounted to a first lens chuck shaft through a lens fixing cup. A second lens chuck shaft has a lens pressing holder, and is arranged coaxially with respect to the first lens chuck shaft. A rotating device has a motor and a transmission member that transmits rotational force of the motor to the first lens chuck shaft. A chucking device clamps the lens by relatively moving the second lens chuck shaft with respect to the first lens chuck shaft in a direction of an axis of rotation with a moving mechanism. A first detector detects an angle of rotation of the second lens chuck shaft when the second lens chuck shaft is rotatingly driven by the first lens chuck shaft rotated by the rotating device in a state where the lens is clamped by the first and second lens chuck shafts. A controller controls processing based on a result of detection by the first detector.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an eyeglass lens grinding apparatus for grinding the periphery of an eyeglass lens. 
     An apparatus is known, in which a subject lens is clamped by two lens rotating shafts, the lens is rotated by synchronously rotating these two lens rotating shafts by mechanically linking them by means of pulleys, gears, and timing belts, and the lens is ground by moving the lens rotating shafts relative to an abrasive wheel. 
     In processing, a mounting jig such as a suction cup secured to the front surface side of the lens is fitted to a cup holder provided on one lens rotating shaft, the other lens rotating shaft having a lens holder is moved toward the cup holder to press and clamp the lens. An angle of rotation of the lens during grinding is controlled using a pulse motor which rotates the lens rotating shafts synchronously. 
     If the force (chuck pressure) with which the lens is pressed by the two lens rotating shafts is weak, the so-called axial offset occurs in which an actual axial angle of the lens is not coincident with an intended angle of rotation of the lens. 
     Major factors causing this axial offset are a processing error that occurs due to the deformation of a rubber portion of the mounting jig caused by the processing resistance applied by the abrasive wheel during lens grinding, and an error that occurs in the controlled angle of the axis of rotation of the lens due to an insufficient rigidity of a lens rotating mechanism section. The axial offset deteriorates the accuracy of the axial angle of the lens and hinders the accurate reproducibility of the finished shape. 
     The reduction of the axial offset depends solely on the reduction of the deformation amount of the rubber portion by increasing the chuck pressure to apply a strong pressure to the rubber portion of the mounting jig. However, if an excessively large chuck pressure is applied, the coating film or layer on the lens surface is damaged or broken and, in the case of a glass lens, the lens itself is broken. 
     SUMMARY OF THE INVENTION 
     In view of the above-described problems, it is an object of the present invention to provide an eyeglass lens grinding apparatus which makes it possible to effect highly accurate grinding by preventing an axial offset, lens breakage, and coating breakage. 
     The present invention provides the followings: 
     (1) An eyeglass lens grinding apparatus for grinding a periphery of a lens, the apparatus comprising: 
     processing means, having abrasive wheels, for processing the lens while depressing the lens onto at least one of the abrasive wheels or vice versa; 
     a first lens chuck shaft to which the lens is fixedly mounted through a lens fixing cup; 
     a second lens chuck shaft having a lens pressing holder, which is arranged coaxially with respect to the first lens chuck shaft; 
     rotating means for rotating the first lens chuck shaft; 
     chucking means for clamping the lens by relatively moving the second lens chuck shaft with respect to the first lens chuck shaft in a direction of an axis of rotation; 
     first detection means for detecting an angle of rotation of the second lens chuck shaft when the second lens chuck shaft is rotatingly driven by the first lens chuck shaft rotated by the rotating means in a state where the lens is clamped by the first and second lens chuck shafts; and 
     control means for controlling processing based on a result of detection by the first detection means; 
     (2) The eyeglass lens grinding apparatus according to (1), wherein the first and second chuck shafts are rotatable independently of each other. 
     (3) The eyeglass lens grinding apparatus according to (1), wherein the second lens chuck shaft is not rotated by the rotating means when the lens is not clamped, whereas the second lens chuck shaft is rotated in synchronism with the first lens chuck shaft by the rotating means when the lens is clamped. 
     (4) The eyeglass lens grinding apparatus according to (1), further comprising: 
     second detection means for detecting an angle of rotation of the first lens chuck shaft; 
     calculation means for obtaining an angular deviation between the angle of rotation detected by the first detection means and the angle of rotation detected by the second detection means; 
     varying means for varying processing pressure based on the angular deviation thus obtained. 
     (5) The eyeglass lens grinding apparatus according to (4), wherein the rotating means includes a pulse motor, and the second detection means detects the angle of rotation of the first lens chuck shaft driven by the pulse motor. 
     (6) The eyeglass lens grinding apparatus according to (4), wherein the processing means includes moving means, having a motor, for moving the first and second lens chuck shafts toward the abrasive wheels, and the varying means varies rotational torque of the motor based on the angular deviation thus obtained. 
     (7) The eyeglass lens grinding apparatus according to (1), wherein the processing means includes moving means for moving the first and second lens chuck shafts toward the abrasive wheels, and the control means controls the moving means based on the result of detection by the first detection means. 
     (8) The eyeglass lens grinding apparatus according to (7), wherein the control means controls the moving means so as to vary a axis-to-axis distance between a rotational axis of the lens and a rotational axis of the abrasive wheels. 
     (9) An eyeglass lens grinding apparatus for grinding a periphery of a lens, the apparatus comprising: 
     a processing device having abrasive wheels, which processes the lens while depressing the lens onto at least one of the abrasive wheels rotatingly driven by an abrasive wheel rotating motor, or vice versa; 
     a first lens chuck shaft to which the lens is fixedly mounted through a lens fixing cup; 
     a second lens chuck shaft having a lens pressing holder, which is arranged coaxially with respect to the first lens chuck shaft; 
     a rotating device having a motor and a transmission member which transmits rotational force of the motor to the first lens chuck shaft; 
     a chucking device which clamps the lens by relatively moving the second lens chuck shaft with respect to the first lens chuck shaft in a direction of an axis of rotation with a moving mechanism; 
     a first detector, which detects an angle of rotation of the second lens chuck shaft when the second lens chuck shaft is rotatingly driven by the first lens chuck shaft rotated by the rotating device in a state where the lens is clamped by the first and second lens chuck shafts; and 
     a controller, which controls processing based on a result of detection by the first detector. 
     (10) The eyeglass lens grinding apparatus according to (9), wherein the moving mechanism includes a motor and a motion-converting member which converts rotational motion of the motor to a linear motion in a direction of an axis about which the first and second lens chuck shafts are rotatable. 
     (11) The eyeglass lens grinding apparatus according to (9), wherein the first and second lens chuck shafts are rotatable independently of each other. 
     (12) The eyeglass lens grinding apparatus according to (9), further comprising: 
     a second detector, which detects an angle of rotation of the first lens chuck shaft; 
     wherein the controller obtains an angular deviation between the angle of rotation detected by the first detector and the angle of rotation detected by the second detector, and varies processing pressure based on the angular deviation thus obtained. 
     (13) The eyeglass lens grinding apparatus according to (12), wherein the motor included in the rotating device is a pulse motor, and the second detector detects the angle of rotation of the first lens chuck shaft driven by the pulse motor. 
     (14) The eyeglass lens grinding apparatus according to (12), wherein the processing device includes a moving device having a lens moving motor, which moves the first and second lens chuck shafts toward the abrasive wheels, and the controller controls rotational torque of the lens moving motor based on the angular deviation thus obtained. 
     (15) The eyeglass lens grinding apparatus according to (9), wherein the processing device includes a moving device having a lens moving motor, which moves the first and second lens chuck shafts toward the abrasive wheels, and the controller controls the moving device based on the result of detection by the first detector. 
     (16) The eyeglass lens grinding apparatus according to (15), wherein the controller controls the moving device so as to vary an axis-to-axis distance between a rotational axis of the lens and a rotational axis of the abrasive wheels. 
     In accordance with the present invention, since processing is controlled while monitoring (detecting) the axial angle of the subject lens which actually rotates, processing becomes possible in which the possibility of axial offset is extremely small. 
     Further, by monitoring (detecting) the angle of offset between the drive shaft and the subject lens (the driven shaft), the lens can be processed with an optimum load suitable for the lens, and the processing can be performed efficiently in the shortest time while maintaining the processing accuracy. 
     Moreover, it is possible to lower the chuck pressure, and process the lens while avoiding the lens breakage and coating breakage. 
     The present disclosure relates to the subject matter contained in Japanese patent application No. Hei. 10-148726 (filed on May 29, 1998), which is expressly incorporated herein by reference in its entirety. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a perspective view illustrating an overall configuration of an eyeglass lens grinding apparatus in accordance with the present invention; 
     FIG. 2 is a schematic diagram illustrating the construction of an abrasive-wheel rotating section and a carriage section; 
     FIG. 3 is a view, taken in the direction of A in FIG. 1, of the carriage section; 
     FIG. 4 is a diagram illustrating a lens chuck mechanism; 
     FIG. 5 is a block diagram of essential portions of a control system; and 
     FIG.  6 A and FIG. 6B are diagrams for explaining the operation of changing the lens rotation corresponding to an unprocessed amount. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the accompanying drawings, a description will be given of an embodiment of the present invention. FIG. 1 is a perspective view illustrating an overall configuration of an eyeglass lens grinding apparatus in accordance with the present invention. Arranged on a body base  1  are an abrasive-wheel rotating section  2  for rotating an abrasive wheel group  20 , a carriage section  3  for bringing the subject lens clamped by two lens chuck shafts into pressure contact with the abrasive wheel group  20 , and a lens-shape measuring section  4 . An eyeglass-frame measuring section  5  is incorporated in an upper rear portion of the apparatus, and a display section  6  for displaying results of measurement and processing information as well as an input section  7  having various input switches are arranged on the front surface side of the apparatus casing. 
     Next, a description will be given of the construction of the major sections with reference to FIGS. 1 to  4 . FIG. 2 is a schematic diagram illustrating the construction of the abrasive-wheel rotating section  2  and the carriage section  3 . FIG. 3 is a view, taken in the direction of A in FIG. 1, of the carriage section  3 . FIG. 4 is a diagram illustrating a lens chuck mechanism. 
     Abrasive-wheel Rotating Section 
     The abrasive wheel group  20  includes a rough abrasive wheel  20   a  for glass lenses, a rough abrasive wheel  20   b  for plastic lenses, and a finishing abrasive wheel  20   c  for beveling and plano-processing, and its abrasive-wheel rotating shaft  21  is rotatably held by a spindle unit  22  secured to the base  1 . A pulley  23  is attached to an end of the abrasive-wheel rotating shaft  21 , and the pulley  23  is linked to a pulley  25  attached to a rotating shaft of an AC motor  26  for the rotation of the abrasive wheel through a belt  24 . Consequently, the abrasive wheel group  20  is rotated as the motor  26  is rotated. 
     Carriage Section 
     A substantially H-shaped carriage  300  is arranged to chuck and rotate a subject lens (a lens to be processed) L using two lens chuck shafts  302 L and  302 R. The carriage  300  is rotatable and slidable with respect to a shaft  350  secured to the base  1  and extending in parallel to the abrasive-wheel rotating shaft  21 . Hereafter, a description will be given of a lens chuck mechanism, a lens rotating mechanism, a mechanism for moving the carriage  300  along an X-axis and a mechanism for moving the carriage  300  along a Y-axis, by assuming that the direction in which the carriage  300  is moved in parallel to the abrasive-wheel rotating shaft  21  is the X-axis, and that the direction in which the shaft-to-shaft distance between the lens chuck shafts ( 302 L,  302 R) and the abrasive-wheel rotating shaft  21  is changed by the rotation of the carriage  300  is the Y-axis. 
     (a) Lens Chuck Mechanism 
     As shown in FIG. 4, the left chuck shaft  302 L and the right chuck shaft  302 R are held rotatably and coaxially by a left arm  301 L and a right arm  301 R of the carriage  300 , respectively. The operator aligns and fixes a suction cup  50 , i.e., a fixing jig, to the front surface of the lens L, and mounts an end portion of the suction cup  50  on a cup receiver  303  provided on an end of the left chuck shaft  302 L. 
     A feed screw  310  is rotatably held inside the right arm  301 R and located at the rear of the right chuck shaft  302 R. A pulley  312  is attached to the shaft of a chuck motor  311  secured to the center of the carriage  300 . The rotation of the pulley  312  is transmitted to the feed screw  310  through a belt  313 . A feed nut  315  is disposed inside the feed screw  310  to threadingly engage the feed screw  310 . The rotation of the feed nut  315  is regulated by a key way  318  formed in a screw guide  317 , so that the rotation of the feed screw  310  causes the feed nut  315  to be moved in the chuck shaft direction (i.e. in the X-axis direction). A cup ring  320  is provided for rotatably connecting the right chuck shaft  302 R to a tip of the feed screw  310 . Therefore, the right chuck shaft  302 R is rotatable, and is moved in the axial direction of the chuck shaft by the feed nut  315 . A lens holder (a lens pushing member)  321  is attached to a distal end of the right chuck shaft  302 R, and upon receiving a moving force in the leftward direction in FIG. 4 the lens holder  321  presses the lens L to chuck the lens in cooperation with the left chuck shaft  302 L. The chuck pressure at this time is detected as an electric current flowing across the motor  311 , and the chuck pressure is controlled by supplying a current corresponding to a necessary chuck pressure. 
     The right chuck shaft  302 R is slidably fitted into a pulley  330  rotatably held by bearings. The right chuck shaft  302 R is designed to transmit its rotating force to the pulley  330 . 
     (b) Lens Rotating Mechanism 
     A pulley  340  is attached to the left chuck shaft  302 L which is rotatably held inside the left arm  301 L of the carriage  300 . This pulley  340  is linked to a pulley  343  of a pulse motor  342  which is secured to the rear side of the carriage left arm  301 L through a belt  341 . When the motor  342  rotates, the left chuck shaft  302 L is rotated, and the rotating force of the left chuck shaft  302 L is transmitted to the chucked lens L through the cup receiver  303  and the suction cup  50 , thereby rotating the lens L. During chucking, since the right chuck shaft  302 R is pressed against the lens L through the lens holder  321  as described above, the right chuck shaft  302 R is rotated in accordance with and in synchronism with the angle of rotation of the lens L. The rotation of the right chuck shaft  302 R is transmitted to an encoder  333 , which is attached to the rear of the right arm  301 R, through the pulley  330 , a belt  331 , and a pulley  332 , so that the encoder  333  detects the angle of rotation of the right chuck shaft  302 R. 
     (c) Mechanism for Moving the Carriage in the X-Axis Direction 
     A lower central section of the carriage  300  is held by the bearings  351  and  352  rotatably and slidably with respect to the shaft  350  secured to the base  1 , and an intermediate plate  360  is rotatably secured to an end portion of the left-side bearing  351 . Two cam followers  361  are attached to a rear end of the intermediate plate  360  at a lower portion thereof, and these cam followers  361  nip a guide shaft  362  fixed to the base  1  in parallel positional relation to the shaft  350 . Consequently, the carriage  300  can be moved in the lateral direction (X-axis direction) together with the intermediate plate  360  while being guided by the shaft  350  and the guide shaft  362 . This movement is effected by a pulse motor  363  for the X-axis movement, which is secured to the base  1 . A belt  366  is suspended between a pulley  364  attached to the rotating shaft of the motor  363  and a pulley  365  rotatably supported by the base  1 . A linking member  367  for linking the belt  366  and the intermediate plate  360  is secured to the belt  366 . With this arrangement, the motor  363  can move the carriage  300  in the X-axis direction. 
     (d) Mechanism for Moving the Carriage in the Y-Axis Direction 
     A servo motor  370  for the Y-axis movement is fixed to the intermediate plat  360  to rotate the carriage  300  about the shaft  350 . The motor  370  has an encoder  371  for detecting the angle of rotation. A gear  372  is attached to the rotating shaft of the motor  370 , and the gear  372  meshes with a gear  373  fixed to the bearing  351 . Accordingly, the carriage  300  can be rotated about the shaft  350  as the motor  370  is rotatingly driven, thereby making it possible to control the Y-axis movement, i.e. the shaft-to-shaft distance between the abrasive-wheel rotating shaft  21  and the lens chuck shafts (the chuck shafts  302 L and  302 R) (see FIG.  3 ). Since the servo motor is used for the Y-axis movement, it becomes possible to provide accurate control of the amount of movement and control of rotational torque in comparison with a pulse motor which has the possibility of undergoing an out-of-step state. The encoder  371  detects the amount of movement of the carriage  300  in the Y-axis direction on the basis of the angle of rotation by the motor  370 . 
     A sensor plate  375  is provided in the rear of the left arm  301 L of the carriage  300 , and as its position is detected by a sensor  376  fixed to the intermediate plate  360 , the position of the original point of the rotation of the carriage  300  can be ascertained. 
     Next, referring to a block diagram of essential portions of a control system shown in FIG. 5, a description will be given of the operation of the apparatus. First, the shape of an eyeglass frame to which a lens is to be fitted is measured by the eyeglass-frame measuring section  5 . If a NEXT DATA switch  701  of the input section  7  is pressed, the measured data is stored in a data memory  101 , and a target lens shape F is simultaneously displayed on a display of the display section  6 . The operator inputs layout data, such as the PD value of the wearer, the FPD value of the eyeglass frame, and the optical center height, by operating the switches of the input section  7 . The operator also enters processing conditions including the material of the lens, the material of the frame, and the processing mode, and the like. 
     Upon completion of the entry of the processing conditions, the operator mounts the lens L with the suction cup  50  attached thereto onto the cup holder  303  on the left chuck shaft  302 L side, and then presses a CHUCK switch  702 . A control section  100  moves the right chuck shaft  302 R by driving the motor  311  through a driver  110  so as to chuck the lens L. Since the chuck pressure at this time is detected as the current flowing across the motor  311 , the control section  100  controls the electric power supplied to the motor  311 , in order to set the chuck pressure to a predetermined level set so as not to cause coating breakage and lens breakage. 
     After completion of the preparation of processing, the operator presses a START switch  703  to start processing. The control section  100  sequentially performs the lens shape measurement and the designated processing in accordance with a processing sequence program on the basis of the inputted data, processing conditions, and the like. 
     The control section  100  obtains processing radius vector information on the basis of the inputted lens data and layout data (refer to U.S. Pat. No. 5,347,762). Subsequently, the control section  100  measures the shape of the lens L using the lens-shape measuring section  4 , and determines whether the lens L can be processed into the target lens shape. The rotation of the lens L is controlled by driving the motor  342  connected to a driver  111 , the movement of the carriage  300  in the Y-axis direction is controlled by driving the motor  370  connected to a driver  113 , and the movement of the carriage  300  in the X-axis direction is controlled by driving the motor  363  connected to a driver  112 , to thereby move the lens L to a measuring position. Subsequently, the lens-shape measuring section  4  is operated to obtain shape information based on the processing radius vector information (the construction of the lens-shape measuring section  4  and the measuring operation are basically similar to those described in U.S. Pat. No. 5,347,762). 
     Upon completion of the lens shape measurement, grinding is performed in accordance with the designated processing mode. First, processing starts with rough grinding. The control section  100  moves the carriage  300  using the motor  363  so that the lens L is located above the rough abrasive wheel  20   a  for glass lenses or the rough abrasive wheel  20   b  for plastic lenses depending on the designated lens material. Subsequently, the carriage  300  is moved toward the abrasive wheel side by the motor  370 , and rough grinding is performed while rotating the lens L. 
     Since the control section  100  has obtained data on the shaft-to-shaft distance between the lens chuck shafts and the abrasive-wheel rotating shaft with respect to the angle of rotation of the lens, the control section  100  controls the movement of the carriage  300  in the Y-axis direction by the rotation of the motor  370  in accordance with the shaft-to-shaft distance data. As the carriage  300  is moved, the lens L chucked by the two lens chuck shafts is brought into pressure contact with the rough abrasive wheel, and is subjected to grinding. 
     During lens grinding, the lens L is rotated by the rotatively driving force on the left chuck shaft  302 L side, and is ground while receiving the grinding resistance from the abrasive wheel. At this time, if the processing resistance is large with respect to the retaining force of the chuck-pressure on the right chuck shaft  302 R, the rubber portion of the suction cup  50  is deformed, so that the actual angle of rotation of the lens deviates from the controlled angle of the pulse motor  342  for lens rotation. However, since the right chuck shaft  302 R is pressed against the lens L and rotated in accordance with the left chuck shaft  302 L, the right chuck shaft  302 R rotates in synchronism with the angle of rotation of the lens L. This angle of rotation is detected by the encoder  333 , and the control section  100  manages the processing configuration in accordance with the detected angle of rotation. This makes it possible to eliminate the axial offset and perform the high-accuracy processing even if the suction cup  50  is somewhat deformed and/or an excessively large chuck pressure is not applied. 
     In the event that a large angular deviation (not smaller than a predetermined angular deviation) is found between the rotation of the drive shaft (i.e. the left chuck shaft  302 L) driven by the pulse motor  342  and the rotation of the driven shaft (i.e. the right chuck shaft  302 R) detected by the encoder  333 , a determination is made such that a large load is applied to the lens L, on the basis of which the motor  370  for moving the carriage  300  is controlled to lower the processing pressure and avoid the application of the large load. Alternatively, the large load applied to the lens L may be removed by stopping the rotative driving of the motor  342  or slightly reversing the motor  342 . This makes it possible to continuously apply an optimum processing load to the lens without changing the chuck pressure depending on the difference in lens material. Accordingly, processing can be effected efficiently in the shortest time while maintaining the processing accuracy. 
     In addition, during the lens grinding, the rotational torque of the motor  370  (motor load current) is detected by the driver  113  and fed back to the control section  100 . The control section  100  controls the rotational torque of the motor  370  through electric power applied thereto, thereby controlling the processing pressure of the lens L upon the abrasive wheel. This makes it possible to continuously process the lens with an appropriate processing pressure while preventing lens breakage without the need of a complex relief mechanism. 
     Further, the control section  100  obtains the amount of movement of the carriage  300  (the shaft-to-shaft distance between the lens chuck shafts and the abrasive-wheel rotating shaft) on the basis of the detection signal inputted from the encoder  371  provided on the motor  370 , and thereby obtains information on the current configuration of the lens being processed with respect to the angle of rotation of the lens. The control section  100  changes the processing pressure (the set value of the rotational torque of the motor  370 ) in accordance with the current configuration thus obtained. That is, if the distance from the lens chuck shafts to a point at which the processing is complete is large, the processing is started with a weaker processing pressure caused by the lowering of the carriage  300 , and as the distance to the processing complete point is shorter, the processing pressure is gradually increased. In general, if the processing diameter of the lens is large, the resistance against the lens chuck shafts is large. Therefore, by changing the processing pressure depending on the processing diameter of the lens in the above-described manner, the lens can be processed while suppressing the axial offset with respect to the retaining force of the chucking. 
     Concurrently, the control section  100  can obtain the amount of movement of the carriage  300  on the basis of the detection signal inputted from the encoder  371 , to thereby obtain, from this amount of movement and the amount of movement until completion of rough grinding recognized from the processing radius vector information, the information on how degree the unprocessed portion (the unprocessed amount) remains with respect to the angle of rotation of the lens. Since the unprocessed amount can be obtained as quantitative information, it is possible to perform such a processing that a portion of the lens where the unprocessed amount is large is ground in a concentrated manner, whereas a portion of the lens where the unprocessed amount is small is ground with the increased speed of the lens rotation. This makes it possible to shorten the overall processing time. 
     For example, if the lens L is processed into a lens shape f 1  while being rotated as shown in FIG. 6A, the rotating speed of the lens is made faster than the initial speed when such a portion (or range) B of the lens where the unprocessed amount is smaller than a predetermined reference (where the unprocessed amount is sufficiently small such that the processing will be complete only by a single rotation of the lens) is ground. As shown in FIG. 6B, when the processing completion is partially obtained on the lens L (or when there appears a portion where the remaining unprocessed amount is sufficiently small such that the processing will be complete only by another single rotation of the lens), the rotating direction of the lens may be changed for that portion, such as a processing-completed portions C 1  and C 2 , during the processing of the lens. In this case as well, the control section  100  obtains information on the processing-completion portions on the basis of the detection signal from the encoder  371 , and reversely rotates the lens by reversing the motor  342  through the driver  111  so as not to process such processing-completion portions (so as to eliminate the waste movement of the abrasive wheel group  20  with respect to the lens L). Consequently, it is possible to reduce the amount of rotation of the lens which is not associated with the grinding. Therefore, the grinding efficiency with respect to the rotation of the lens is heightened, thereby making it possible to reduce the overall processing time. 
     Upon completion of rough grinding, the operation proceeds to finish processing using the finishing abrasive wheel  20   c.  At this time as well, the processing configuration is managed and controlled on the basis of the angle of rotation of the right chuck shaft  302 R detected by the encoder  333 . During the finish processing as well, the efficient processing with high accuracy can be realized by changing the processing pressure and the rotating direction and rotating speed of the lens in accordance with the configuration of the lens being processed and the unprocessed amount in the same way as during rough grinding.