JP3142362B2 - Lens grinding apparatus and lens grinding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens grinding apparatus and a lens grinding method for grinding an unprocessed lens into a shape conforming to the lens frame based on shape data of the lens frame of the frame.

[0002]

2. Description of the Related Art In the case of grinding an outer peripheral shape of a circular lens so as to conform to an eyeglass frame, generally, a lens grinding apparatus for grinding the peripheral edge of a lens before processing with a cylindrical grindstone based on lens frame shape data of the eyeglass frame. Is used. For example, WO 88/04974 discloses that a lens is pressed from the front and rear surfaces and held by a lens axis, the lens axis is rotated at a constant speed by an AC motor, and the rotation state of the lens axis is read by an encoder. There is disclosed a lens grinding apparatus that grinds an unprocessed lens into a shape that matches a lens frame while controlling the distance between a grindstone and a lens axis by a Y-axis motor based on the rotation angle information.

[0003] Such a lens grinding apparatus has an advantage that the peripheral processing of the spectacle lens can be directly performed based on the shape measurement data of the lens frame of the spectacle frame.
However, on the other hand, there are the following disadvantages in terms of the efficiency of the grinding process. Here, the problem of the grinding process by the conventional method will be described with reference to FIG.

Conventionally, a cylindrical grindstone 261 has been used for grinding the spectacle lens 201. FIG. 8 shows the distance H between the rotation center Od of the grindstone 261 and the rotation center Os of the spectacle lens 201, and the radius R of the grindstone 261. A spectacle lens 201 is provided on the side of the grindstone 261.
The grinding wheel 261 and the spectacle lens 201 are rotated with respect to each other by bringing the end faces into contact with a predetermined pressure. At this time, eyeglass lens 2
01 (lens axis) is rotated, and at the same time, the eyeglass lens 201 is pressed against the grindstone 261 while driving the Y-axis motor based on the lens frame shape data (θj, rj) to move the lens axis up and down. Eyeglass lens 201
Is ground into the lens frame shape of the frame.

[0005]

However, when the displacement amount Δr / Δθ of the radial distance r of the spectacle lens 201 is large, the driving amount of the Y-axis motor, that is, the spectacle lens 2
Also, the change of the distance H for moving the object 01 in the vertical direction increases.
What is necessary is that the rotation center Od of the grindstone 261 also has the radius R
Is also fixed. Since the rotation of the lens axis and the vertical movement of the lens axis are controlled at the same time, the displacement amount Δr / Δθ of the spectacle lens 201 is smaller than that of the place where the displacement amount of the radial distance rj is small. In big places,
The cutting pressure on the spectacle lens 201 decreases, and the cutting efficiency also decreases.

That is, the radial distance r of the spectacle lens 201
If the rotational speed of the lens axis is uniformly increased with reference to a portion where the displacement amount is small, the remaining cutting will inevitably occur at a portion where the displacement amount of the radial distance rj is large. Thus, in the grinding process, it is necessary to consider the balance between the rotation of the lens axis and the vertical movement of the lens axis,
If the rotation speed of the lens axis is higher than the vertical movement speed of the lens axis, the grinding accuracy of the end surface of the spectacle lens 201 is reduced.

[0007] Therefore, since it is necessary to correct the shape of the ground lens, if the rotation speed of the lens axis is fixed, the grinding time of the spectacle lens 201 becomes longer as a result. On the other hand, if the rotational speed of the lens axis is determined based on the position where the displacement amount of the radial distance is large, the uncut portion is less likely to occur but the grinding time until finishing the eyeglass lens 201 to the final shape becomes longer. there were.

The present invention has been made in view of the above points, and has as its object to provide a lens grinding apparatus in which the processing efficiency of a processed lens is increased by an inexpensive method. Another object of the present invention is to provide a lens grinding method capable of shortening a grinding time.

[0009]

According to the present invention, there is provided a lens grinding apparatus for grinding a lens before processing into a shape corresponding to the lens frame based on shape data of the lens frame of the frame. A shape data setting means for setting shape data including a radial line for each rotation angle from a reference line and a reference point set on the lens frame;
Calculating means for calculating a displacement amount of a radial distance from the reference point which changes at every predetermined rotation angle of the lens frame based on the shape data, and a rotation speed of a lens shaft for holding and rotating the unprocessed lens Speed determining means for determining the magnitude of the displacement amount in inverse proportion to the magnitude of the displacement amount, and controlling the speed of the lens axis according to the rotation speed data determined by the speed determining means to control the grinding by the rotating grindstone. And a lens grinding control means.

According to the present invention, there is provided a lens grinding method for grinding a lens before processing into a shape corresponding to the lens frame based on shape data of the lens frame of the frame in order to shorten a grinding time. Set the shape data including the radial line for each rotation angle from the reference line and the reference point set to, calculate the displacement amount of the radial distance from the reference point for each predetermined rotation angle of the lens frame, A lens grinding method is provided in which the rotational speed of a lens shaft holding the unprocessed lens is controlled with a magnitude inversely proportional to the calculated displacement amount to control grinding by a rotating grindstone. You.

[0011]

A feature of the operation of the present invention is that the rotation speed of the lens axis is controlled in accordance with the amount of vertical movement of the lens axis.
As a result, the time required to grind the spectacle lens into a lens frame shape can be reduced. That is, if the displacement is small, the rotation speed is increased, and if the displacement is large, the rotation speed is decreased. Thus, the grinding accuracy in the lens grinding can be increased and the grinding time can be reduced.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating an example of a lens grinding device.

The lens grinding device includes a shape data measuring means 1
00, a lens grinding means 200, an arithmetic control circuit 300 and a data input means 400 as main elements. The shape data measuring means 100 includes a frame shape measuring unit 110 and a frame shape measuring unit 1 for measuring the shape of the lens frame.
10 and a frame shape measuring circuit 120 connecting the arithmetic and control circuit 300. The shape data measuring means 100 measures shape data of a frame in which the processed lens is framed.

The lens grinding means 200 has a lens grinding section, a motor drive circuit, and the like, and holds a lens to be processed on a rotating shaft coincident with the lens optical center based on grinding data, as will be described later in detail. Lens axis motor 23 for grinding
2 and a Y-axis motor 252, and drive circuits 232a and 252a for driving these motors.

The arithmetic control circuit 300 has a microprocessor configuration, and includes a data correcting means 310, an arithmetic means 3
20, grinding data 330 for controlling the lens grinding means 200, lens axis rotation speed data 340, and radial distance displacement amount calculation means 350. The data correcting means 310 calculates a pair of lens frame shape data of the frame by inverting the shape data of one of the lens frames having the origin at the geometric center of the lens frame with respect to the symmetry axis of the left and right lens frames of the frame, Correction is made to a pair of grinding data 330 having the origin at the lens optical center of the lens frame based on the shift amount data. The calculating means 320 inverts the shape data of one lens frame and converts it into the other shape data, and further the radial distance displacement amount calculating means 350 changes at every predetermined rotation angle of the lens frame based on this shape data. The amount of displacement of the radial distance from the reference point is calculated.

The data input means 400 stores numerical keys (shift amount input means) 401 for inputting the shift amount, a selection key 402 for selecting whether the lens is right or left, and saves the shape data of the frame in an IC card or the like. It comprises an IC card reader (shape data reading means) 403 for reading shape data from this IC card. That is, the shape data is measured by the shape data measuring means 100,
The IC card reader 403 is stored in the C card.
May be read by

FIG. 2 is a detailed view showing the frame shape measuring section 110. In order to set the shape data of the lens frame in which the processed lens is placed, the spectacle frame 111 is fixedly held at a predetermined position on a frame table (not shown) by a frame holding member. At this position, the tracing stylus 112 comes into contact with the inner peripheral groove of the lens frame of the spectacle frame 111. The tracing stylus 112 is fixedly provided on a rotating plate 114 that rotates around a rotating shaft 113, and while being constrained by a sliding plate 115 constituting a sliding mechanism,
It can move along the inner peripheral groove of the lens frame of the spectacle frame 111. The rotation angle when the tracing stylus 112 moves is defined by the angle at which the tracing stylus motor 116 rotates the rotating shaft 113.
The amount of displacement from the reference position of No. 2 is obtained by further converting the amount by which the slide plate 115 slides in the left-right direction in the drawing into a rotation angle.
It is transmitted to the potentiometer 117 and can be measured. The rotation angle of the rotary plate 114 from the reference position is measured by the rotary encoder 118, and the origin position of the tracing stylus motor 116 can be detected by the origin position detection circuit 119 composed of a photo interrupter.

FIG. 3 is a block diagram showing the frame shape measuring circuit 120. Move the tracing stylus 112 to the spectacle frame 11
The motor drive circuit 11 is held in contact with the inner periphery of the first lens frame.
A rotation command is given to 6a to drive the tracing stylus motor 116. The measuring element 112 includes a rotating shaft 113, a rotating plate 114,
And the slide frame 115 and the eyeglass frame 1
11 moves along the inner peripheral groove of the rim. The rotation angle θ of the rotating plate 114 at this time is output from the rotary encoder 118 and counted by the counter 118a. Also,
The displacement amount r of the tracing stylus 112 from the measurement reference position is output from the potentiometer 117, and the A / D conversion circuit 117a
Is converted to a digital value. When the tracing stylus 112 makes one rotation of the inner circumferential groove of the rim of the spectacle frame 111, one rotation signal is output from the counter 118a, and a stop command is given from the arithmetic control means 300 to the motor drive circuit 116a.

The eyeglass frame left / right eye determination circuit 119
a determines whether the tracing stylus 112 is in contact with the rim of the left or right eye of the spectacle frame 111, and determines the count value of the rotation angle θ and the digital value of the displacement amount r by a predetermined value of the arithmetic and control circuit 300 described later. Store in storage area.

In the frame shape measuring section 110, the tracing stylus moves along the inner peripheral groove of the lens frame while maintaining a predetermined contact pressure, and the shape data of the lens frame is read. The displacement amount r of the tracing stylus 112 corresponds to the length of the moving radius of the lens frame of the spectacle frame 111 (hereinafter, simply referred to as the moving radius), and the rotation angle θ of the rotating plate 114 corresponds to the rotation angle of the frame of the spectacle frame 111. Equivalent to.

FIG. 4 is a detailed view showing a lens grinding unit constituting the lens grinding apparatus of FIG. FIG. 5 is a block diagram showing a lens grinding circuit. In the lens grinding unit of FIG. 4, the horizontal direction is the Z axis, and the vertical direction is the Y axis. The lens grinding unit includes a storage box 202 that can move in the Z-axis direction while supporting the lens 201 to be processed. The storage box 202 is moved in the Z-axis direction on the base 203 of the lens grinding unit, and further, the base 203 is moved in the Y-axis direction. Enable. The grinding pressure adjustment mechanism 210 adjusts the grinding pressure of the lens 201 before processing, and positions the base 203 on which the storage box 202 is mounted in the Y-axis direction. The Z-axis direction drive mechanism 220 is
2 together with the unprocessed lens 201 in the left-right direction (Z
Axis). The lens rotation mechanism 230 for processing
A lens shaft 231 for rotating the pre-processing lens 201 is provided.
The lens 40 is rotated while holding the unprocessed lens 201 by 40. The Y-axis direction driving mechanism 250
1 is moved by a predetermined amount while being adjusted by the sensor bar 251 fixed to the base 203 in the Y-axis direction. The diamond wheel 261 is provided so as to be rotatable at a predetermined speed by a diamond wheel rotating mechanism 260 to grind the lens 201 before processing.

The base 203 is connected by wire ropes 211a and 211b of the grinding pressure adjusting mechanism 210 and is always lifted upward so that the lens 201 to be processed contacts the diamond wheel 261 with a predetermined grinding pressure. Is controlled. Therefore, the grinding pressure adjusting motor 21
2, the origin position detection sensor 213 detects the origin positions of the wire ropes 211a and 211b,
The unwinding length of the wire rope 211a by the grinding pressure adjusting motor 212 is detected by a winding amount detection sensor 214. In the middle of the wire ropes 211a and 211b, the cutting pressure adjusting spring 2 inserted in the sleeve 215
16 are provided.

As shown in FIG. 5, the origin position detecting circuit 21
3a and the detection signal of the winding amount detection circuit 214a are output to the arithmetic and control circuit 300, and the arithmetic and control circuit 300 calculates the grinding pressure adjustment signal accordingly. The amount of rotation of the grinding pressure adjustment motor 212 is adjusted according to an adjustment signal input to the motor drive circuit 212a.

The pulse motor 2 of the Z-axis direction drive mechanism 220
According to 21, the pre-processing lens 201 is subjected to a plurality of grinding portions (grinding stones) formed on the outer peripheral surface of the diamond wheel 261, for example, a rough grinding portion for rough-grinding the pre-processing lens 201, and bevel grinding (processing of a V-groove). Is moved to the respective positions of the beveled grindstones. The pulse motor 221 of the Z-axis direction drive mechanism 220 includes a pulley 223a,
The clutch 22 is connected via the belt 222 and the pulley 223b.
4 and the pulley 2 on the opposite side of the clutch 224
25, the moving plate 22
7, the storage box 202 is positioned in the Z-axis direction. The amount of movement of the belt 226 via the pulley 228 is converted to the rotation angle of the light shielding plate 229a, and the origin position in the Z-axis direction is detected by the photo interrupter 229.

As shown in FIG. 5, the photo interrupter 2
The origin position detected by the reference numeral 29 is an origin position detecting circuit 229a.
Is output to the arithmetic control circuit 300, and the arithmetic control circuit 300 calculates a Z-axis position command signal according to the grinding data. Then, the Z-axis pulse motor 221 rotates according to a command signal input to the motor drive circuit 221a.

The lens 201 to be processed is rotated about its lens axis 231 by the lens axis pulse motor 232 of the lens rotating mechanism 230 for processing. The rotation of the lens axis pulse motor 232 includes four pulleys 233a to 233a.
The light is transmitted to the lens shaft 231 by 3d and two belts 234a and 234b. Diamond wheel 261
, The rotation angle of the pre-processing lens 201 is instructed based on the lens axis rotation speed data 340. That is, in the present invention, the encoder is not attached to the lens shaft 231 and the lens shaft 231 is controlled by a pulse motor 232 instead of the conventional AC motor, and therefore, the prior art (WO 88/04974). No.).

The lens pressing motor 241 of the lens chuck mechanism 240 for processing has the lens 2
01, or a motor that rotates so as to remove the processed lens, including a pulley 243a and a belt 242.
And a lens shaft 231 via a pulley 243b.

As shown in FIG. 5, the motor drive circuit 241
a from the arithmetic control circuit 300 to the lens 201 before processing.
Is supplied to the motor drive circuit 241a at a predetermined timing based on the exchange command of the
01 can be exchanged.

The Y-axis servomotor 252 of the Y-axis direction driving mechanism 250 is connected to one end of a screw shaft 254 parallel to the Y-axis by pulleys 255 via pulleys 253a and 253b.
The screw shaft 254 is rotated at a predetermined speed. And
The switching bar 256 screwed to the screw shaft 254 moves in the Y-axis direction by the rotation of the Y-axis servomotor 252, and is configured to press the switching button 257 from below in FIG. . The switching button 257 is provided at one end of the shield bar 257a, and a photo interrupter 257b for detecting the end of grinding is provided at the other end of the shield bar 257a. The shielding bar 257a is movable at the tip end of the sensor bar 251 in the Y-axis direction and is mounted via a predetermined elastic compression spring. The shielding bar 257a comes into contact with the switching bar 256 to push up the sensor bar 251 in the Y-axis direction. And regulates the positions of the storage box 202 and the base 203 in the Y-axis direction. The photo interrupter 257b is a shielding bar 25.
When the shielding bar 257a moves while the shutter 7a is pressed by the switching bar 256, the pressing center position of the unprocessed lens 201 moves downward in FIG. The other end of the screw shaft 254 is a belt 258
Encoder 25 for detecting the position in the Y-axis direction by using
9 are provided.

As shown in FIG. 5, the movement amount detected by the encoder 259 is output from a movement amount detection circuit 259a to a counter circuit 259b, and the counter circuit 259b
The count value at b is sent to the arithmetic and control circuit 300. Thus, the amount of movement of the shielding rod 257a is determined, and the rotation center of the lens 201 before processing and the diamond wheel 261 are determined.
The distance to the center of rotation can be measured. The Y-axis servomotor 252 is driven by lens frame grinding data instructed to the motor drive circuit 252a, and is controlled in relation to the rotation angle θ of the lens 201 before processing. And
When the pre-processing lens 201 is ground over 360 °, the shielding bar 257a is no longer pushed by the switching bar 256 by the photo interrupter 257b for detecting the end of grinding, and a signal is output from the end-of-grinding detection circuit 257c. In response to this signal, the arithmetic and control circuit 300 inverts the rotation direction of the lens 201 before processing, and further instructs the timing to end the grinding.

In the diamond wheel rotating mechanism 260, when the grinding wheel rotating shaft motor 262 is driven, the pulley 264 is driven.
a, the diamond wheel 261 is rotated via the belt 263 and the pulley 264b.
Are simultaneously rotated. As shown in FIG. 5, the rotation of the grindstone rotating shaft motor 262 is controlled at a predetermined speed in accordance with a command from the arithmetic and control circuit 300 to the motor drive circuit 262a. Thus, the grinding is performed while the grindstone is in contact with the peripheral portion of the unprocessed lens 201 and rotates with each other.

FIG. 6 is a block diagram showing an arithmetic and control circuit 300 for controlling the frame shape measuring section 110 and the lens grinding means 200. The CPU 301 performs predetermined arithmetic processing such as a displacement amount of a radial distance from a reference point that changes at every predetermined rotation angle of the lens frame based on input frame shape measurement data and the like, and the processing result is stored in the RAM 302. Is done. The ROM 303 has an arithmetic program for determining the rotation speed of the lens shaft 231 described below, an arithmetic program for inverting the shape data of the lens frame,
A calculation program for obtaining the left and right lens optical centers in the lens frame based on the shift amount data, a calculation program for obtaining the envelope corresponding to the radius value of the diamond wheel 261 from the shape data, and the center axis of the lens axis being the grinding wheel rotation So that it is located on the envelope with respect to the center axis of the shaft,
An arithmetic program for converting the shape data of the lens frame into the grinding data is stored.

Next, the procedure of grinding by the lens grinding apparatus of the present invention shown in FIGS. 1 to 6 will be described.
FIG. 7 is a flowchart illustrating an embodiment of the lens grinding method. In the figure, a numerical value following S indicates a step number. In these processes, the diamond wheel 261 shown in FIG.
The rotational speed and the vertical position are simultaneously controlled.

[S1] A radial distance is determined for each predetermined angle from a reference line and a reference point set on the lens frame, and shape data is set. Shape data is frame shape measurement circuit 1
20 or read from the data input unit 400 using an IC card. Here, the reference line and the reference point can be set arbitrarily.

[S2] The set shape data is corrected by the data correcting means 310 into shape data having the origin at the optical center of the lens set in the lens frame. This correction data is calculated from the shape data given as polar coordinate data, but shape data converted to rectangular coordinate data may be used.

[S3] Based on the shape data in step S2, a displacement amount of the radial distance that changes for each predetermined rotation angle of the lens shaft 231 is calculated. In the calculation of the displacement amount, the shape data in step S1 can be used. However, since the shape data used at the time of lens grinding is correction data with the optical center of the lens as the origin, the calculation process is facilitated. Therefore, it is desirable to use the corrected shape data.

[S4] Based on the displacement of the radial distance obtained in step S3, the lens shaft 231 for each predetermined rotation angle is determined.
Determine the rotational speed of. In determining the rotation speed, a rotation speed table can be used.

That is, the rotation speed ω corresponding to the displacement amount Δr / Δθ of the radial distance r of the unprocessed lens 201 of the glasses is set, and the speed data (ωi, θi) for each rotation angle θ from the reference line is set. ) Is stored in the RAM 302 as lens axis rotation speed data 340. In this case, the displacement amount of the radial distance can be read by the number of pulses instead of the length data.

[S5] The optical center of the unprocessed lens 201 is mounted so as to coincide with the lens axis 231, and the speed of the lens axis 231 is controlled by the speed data determined in step S4. The lens grinding is executed while controlling the position at the position based on the shape data corrected at step S2.

Thus, if the unprocessed lens 201 is ground into the lens frame shape as shown in FIG. 8, the movement amount of the lens shaft 231 in the vertical direction becomes large at a position where the displacement amount Δr / Δθ of the radial distance is large. Even so, the lens shaft 231 can be controlled so as to rotate slowly in proportion thereto, so that the remaining grinding is reduced. Conversely, the displacement amount of the radial distance Δr / Δ
At a position where θ is small, the lens shaft 231 can be rotated at a high speed, and the grinding efficiency is improved.

As described in the present embodiment, even if the set shape data is not corrected (step S2), step S1 is performed.
It is also possible to carry out grinding directly based on the shape data of. However, in this case, it is necessary to mount the unprocessed lens on the lens shaft 231 so as to match the reference point set in step S1. Then, in step S5, the lens axis 231 is set.
The position where the lens is attached to the camera is also determined by this reference point.

Further, according to the present invention, by storing the template data in advance, for example,
For example, the present invention can be applied to a lens grinding apparatus by copying, which is disclosed in Japanese Patent Application Laid-Open No. 9-209. However, it is necessary to use a pulse motor for the lens shaft rotation motor.

[0043]

As described above, according to the present invention, by controlling the rotation speed of the lens axis in accordance with the amount of vertical movement of the lens axis, the Y-axis motor and the lens axis rotation motor can be prevented from having high performance. It is possible to provide a lens grinding apparatus that can reduce the lens grinding time by an inexpensive method.

Further, since the lens grinding method of the present invention can reduce the remaining grinding, the processed spectacle lens can be framed without correction.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a lens grinding device.

FIG. 2 is a detailed view showing a frame shape measuring unit.

FIG. 3 is a block diagram showing a frame shape measuring circuit.

FIG. 4 is a detailed view showing a lens grinding unit constituting the lens grinding device.

FIG. 5 is a block diagram illustrating a lens grinding circuit.

FIG. 6 is a block diagram illustrating an arithmetic control circuit.

FIG. 7 is a flowchart illustrating an embodiment of a lens grinding method.

FIG. 8 is a view showing a processed lens when there is a displacement amount of a radial distance set in a lens before processing.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 shape data measuring means 200 lens grinding means 300 arithmetic control means 340 lens axis rotation speed data 350 radial distance displacement calculating means 400 data input means

Claims (4)

(57) [Claims] 1. A lens grinding apparatus for grinding an unprocessed lens into a shape corresponding to the lens frame based on shape data of the lens frame of the frame, the lens grinding apparatus comprising: a reference line and a reference point set on the lens frame; Shape data setting means for setting shape data including a radial distance for each rotation angle; and a displacement amount of a radial distance from the reference point, which changes at each predetermined rotation angle of the lens frame, based on the shape data. Calculating means for calculating; a speed determining means for determining a rotation speed of a lens axis for holding and rotating the unprocessed lens by a magnitude inversely proportional to the magnitude of the displacement amount; and a rotation determined by the speed determining means. A lens grinding device, comprising: lens grinding control means for controlling grinding by a rotating grindstone by controlling the speed of a lens axis according to speed data. 2. A lens grinding apparatus for grinding an unprocessed lens into a shape corresponding to the lens frame based on shape data of the lens frame of the frame. Shape data setting means for setting shape data including a radial distance for each rotation angle; andshape data correction means for correcting the shape data to grinding data having an optical center of a lens set in the lens frame as an origin. Calculating means for calculating a displacement amount of a radial distance from the reference point or the origin which changes for each predetermined rotation angle of the lens frame based on the shape data or the correction data; and Speed determining means for determining the rotation speed of the lens axis to be held and rotated by a magnitude inversely proportional to the magnitude of the displacement amount; and the rotation determined by the speed determining means. Lens grinding apparatus comprising: the lens grinding control means for controlling the grinding by the grinding wheel that rotates in the speed control of the lens axis in accordance with the speed data. 3. The method according to claim 1, wherein the shape data setting means includes polar coordinate data (θi, r) based on a radial distance ri for each rotation angle θi.
i) Set (i is 0, 1, in ... n), the calculating means, adjacent radial distance r _i, calculates a difference Δri of r _{i + 1,} in the speed determining means, said difference Δri 3. The lens grinding apparatus according to claim 1, wherein a rotational speed ω that is inversely proportional is determined. 4. A lens grinding method for grinding an unprocessed lens into a shape corresponding to the lens frame based on shape data of the lens frame of the frame, wherein the lens is rotated from a reference line and a reference point set on the lens frame. Setting shape data including a radial distance for each angle; calculating a displacement amount of a radial distance from the reference point for each predetermined rotation angle of the lens frame; a magnitude inversely proportional to the calculated displacement amount A method of controlling the rotation speed of the lens shaft holding the unprocessed lens, and controlling the grinding by the rotating grindstone.