Abrading – Precision device or process - or with condition responsive... – Computer controlled
Reexamination Certificate
1999-06-30
2001-07-17
Eley, Timothy V. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
Computer controlled
C451S009000, C451S043000
Reexamination Certificate
active
06261150
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an eyeglass lens grinding apparatus for grinding the periphery of an eyeglass lens.
An eyeglass lens grinding apparatus is known. After a subject lens is chucked by two lens rotating shafts, the apparatus controls the axis-to-axis distance between an axis of the lens rotating shafts and an axis of an abrasive wheel shaft of a grinding abrasive wheel on the basis of processing data while rotating the lens, thereby grinding the lens in pressure contact with the abrasive wheel. The apparatus of this type has a processing-completion detecting mechanism for detecting whether or not the entire periphery of the lens has been processed in accordance with processing data. In general, the mechanism is designed to detect, through a mechanical contact or using a sensor, whether the axis-to-axis distance between the lens rotating shafts and the abrasive wheel shaft has reached a predetermined distance based on the processing data.
In the case where the lens chucked by the two lens rotating shafts is processed by being brought into pressure contact with the abrasive wheel, the lens rotating shafts are slightly deflected due to their rigidity in a direction in which the lens rotating shafts escape from the abrasive wheel. The lens is clamped through a suction cup; however, if the rigidity of the suction cup portion is weak, the lens is also slightly deflected in the direction in which it escapes from the abrasive wheel. For this reason, the above-described processing-completion detecting mechanism determines the completion of processing at a stage where the actually ground lens is slightly larger than the intended size. This hinders the accurate processing.
As a conventional countermeasure against this problem, even after the completion of processing is detected, the lens is rotated idly until the deflection or distortion is overcome, to ensure that unprocessed portions will be processed.
However, if the number of idle rotations after detection of the completion of processing is set for the purpose of grinding all the lenses with high accuracy and such setting is made on the basis of thick lenses which are difficult to process, then excessive idle rotation (and thus wasteful processing time) is caused in the case of thin lenses even though the thin lenses have been already processed without any unprocessed portions. Conversely, if the setting of the number of idle rotations is insufficient (small), thick lenses cannot be processed with high accuracy.
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 can accurately detect the completion of processing without any excessive idle rotation, thereby making it possible to perform high-accuracy processing.
To attain the above object, the present invention is characterized by having the following features.
(1) An eyeglass lens grinding apparatus for grinding a periphery of a lens to be processed, the apparatus comprising:
lens rotating means, having a lens rotation shaft, for holding and rotating the lens;
abrasive wheel rotating means, having an abrasive wheel rotation shaft, for rotating a lens grinding abrasive wheel;
axis-to-axis distance varying means for varying a distance between an axis of the lens rotation shaft and an axis of the abrasive wheel rotation shaft so that the lens is brought into pressure contact with the abrasive wheel for processing;
detecting means for detecting a state of rotation of the lens or the abrasive wheel;
judging means for judging whether the lens has been completely processed, based on a result of detection by the detecting means.
(2) The eyeglass lens grinding apparatus according to (1), wherein the detecting means detects a rotational torque of the lens or a rotational torque of the abrasive wheel.
(3) The eyeglass lens grinding apparatus according to (2), wherein the judging means judges whether the lens has been completely processed, based on a comparison in which the rotational torque detected by the detecting means is compared with a certain rotational torque.
(4) The eyeglass lens grinding apparatus according to (1), wherein:
the lens rotating means includes a lens rotating motor for rotating the lens rotation shaft;
the abrasive wheel rotating means includes an abrasive wheel rotating motor for rotating the abrasive wheel shaft; and
the detecting means detects a rotational torque of said lens rotating motor or a rotational torque of said abrasive wheel rotating motor.
(5) The eyeglass lens grinding apparatus according to (4), wherein the detecting means detects an electric current supplied to the lens rotating motor or an electric current supplied to the abrasive wheel rotating motor to obtain the rotational torque.
(6). The eyeglass lens grinding apparatus according to (4), wherein the judging means judges whether the lens have been completely processed, based on a comparison in which the rotational torque detected by the detecting means is compared with a certain rotational torque.
(7) The eyeglass lens grinding apparatus according to (1), wherein the detecting means detects a rotational speed of the abrasive wheel or the abrasive wheel rotating shaft.
(8) The eyeglass lens grinding apparatus according to (1), wherein:
the abrasive wheel rotating means includes an abrasive wheel rotating motor, and a transmission member for transmitting a rotational torque of the motor to the abrasive wheel rotating shaft; and
the detecting means detects a rotational speed of the transmission member.
(9) The eyeglass lens grinding apparatus according to (1), further comprising:
input means for inputting data on a shape of an eyeglass frame to which the lens is to be fitted, and data on a layout of the lens with respect to the eyeglass frame;
arithmetic means for obtaining lens processing data based on the data thus inputted; and
control means for controlling operation of the axis-to-axis distance changing means based on the processing data thus obtained.
(10) The eyeglass lens grinding apparatus according to (1), further comprising:
control means for controlling operation of the axis-to-axis distance changing means based on a result of judgement by the judging means.
(11) An eyeglass lens grinding apparatus for grinding a periphery of a lens to be processed, the apparatus comprising:
a lens rotation shaft which holds and rotates the lens;
a lens rotating device having a lens rotating motor and a first transmission member which transmits a rotational torque of the lens rotating motor to the lens rotation shaft;
an abrasive wheel rotation shaft which rotates a lens grinding abrasive wheel;
an abrasive wheel rotating device having an abrasive wheel rotating motor and a second transmission member which transmits a rotational torque of the abrasive wheel rotating motor to the abrasive wheel rotation shaft;
a moving device which causes a relative movement between the lens rotation shaft and the abrasive wheel rotation shaft to vary an axis-to-axis distance between the lens rotation shaft and the abrasive wheel rotation shaft, thereby brining the lens into pressure contact with the abrasive wheel for processing;
a detector which detects a state of rotation of the lens or the abrasive wheel; and
a controller which judges whether the lens has been completely processed, based on a result of detection by the detector.
(12) The eyeglass lens grinding apparatus according to (11), wherein the detector detects the rotational torque of the lens rotating motor or the rotational torque of the abrasive wheel rotating motor.
(13) The eyeglass lens grinding apparatus according to (12), wherein the detector detects an electric current supplied to the lens rotating motor or an electric current supplied to the abrasive wheel rotating motor to obtain the rotational torque.
(14) The eyeglass lens grinding apparatus according to (12), wherein the controller judges whether the lens has been completely processed, based on a comparison in which the rotational torque detected by th
Mizuno Toshiaki
Obayashi Hirokatsu
Eley Timothy V.
Nguyen Dung Van
Nidek Co. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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