Abrading – Precision device or process - or with condition responsive... – By optical sensor
Reexamination Certificate
2000-08-07
2001-12-25
Banks, Derris H. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
By optical sensor
C451S041000
Reexamination Certificate
active
06332827
ABSTRACT:
The invention relates to spectacle lens machining apparatus, in particular a spectacle lens edging machine, having a housing, a machining chamber in the housing, a spectacle lens holding shaft, a flap outwardly sealing the machining chamber, a holder which, upon closure of the flap, transports a rough-cast lens into the region of the spectacle lens holding shaft, and a sensor for detecting the presence and/or the angular position of the rough-cast lens.
Such an apparatus is described in DE 195 37 692 C2 of the same applicant. In the case of this apparatus, the holder has pincers which grip the rough-cast lens on its circumference at diametrically opposite points, or grip a block or sucker mounted on the rough-cast lens, such that the rough-cast lens can be brought with its optical axis into the axis of the spectacle lens holding shaft in an accurately positioned fashion. In accordance with another embodiment, it is possible for there to be present on the holder a controllable suction device acting on a region of an optical surface of the rough-cast lens outside the region of the surface required for holding the rough-cast lens on the spectacle lens holding shaft, such that with the flap folded open it is possible for a rough-cast lens to be inserted into the pincers on the flap or on the suction device. With this known device, the insertion of the rough-cast lens into the pincers on the flap or on the suction device on the flap must be performed so accurately with regard to the optical midpoint of the rough-cast lens that the rough-cast lens held by the holder passes into the region of the spectacle lens holding shaft when the flap is folded back into the closed position, and the optical axis of the rough-cast lens coincides with the axis of rotation of the spectacle lens holding shaft. The rough-cast lens is then taken over by the spectacle lens holding shaft and can be further machined in the usual way.
A sensor arranged in the machine chamber can be used to detect both the presence of a rough-cast lens in the region of the spectacle lens holding shaft and the angular position of the rough-cast lens, it thereby being possible for the spectacle lens holding shaft to be driven by means of this sensor such that it takes over the rough-cast lens accurately in angular terms. The operator can therefore insert the rough-cast lens into the holder without having to take account of the angular position of the rough-cast lens, but, as already mentioned, the rough-cast lens must be inserted into the holder with regard to its optical axis so accurately that this optical axis of the rough-cast lens corresponds to the axis of rotation of the spectacle lens holding shaft when the rough-cast lens is clamped by means of the spectacle lens holding shaft.
DE 195 27 222 C2 of the same applicant discloses, furthermore, an installation for grinding at least the circumferential edge of spectacle lenses, and a method for taking account by computer of the position of a rough-cast lens held on a holding head of the installation. In this case, the position of a rough-cast lens mounted on a holding head of a rotatable shaft of a CNC-controlled installation for grinding spectacle lenses in accordance with a prescribable outline of the respective spectacle lens is taken into account by computer in such a way that the position of the rough-cast lens, held on the holding head, with regard to the optical axis with reference to the axis of the rotatable shaft and/or the axial position of a cylindrical or prismatic cut, or with regard to conventional markings on the rough-cast lens is measured by means of a detection device which converts measured values into electric signals by means of a converter, the signals are input into the control device, constructed as a computer, of the installation, and the signals are incorporated by calculation into the prescribed outline of the spectacle lens, if appropriate into the axial position of a cylindrical or prismatic spectacle lens and/or into the decentration values in the case of CNC-controlled grinding of the spectacle lens.
In the case of this installation, the detection device is arranged coaxially with the holding shaft, which is constructed as a hollow shaft, and preferably consists of a CCD camera.
Both the spectacle lens machining apparatus in accordance with DE 195 37 692 C2, and the installation in accordance with DE 195 27 222 C2 have proved themselves, but it has emerged that it is desirable to simplify the mounting of a rough-cast lens onto a holder on a flap, and to avoid a complicated detection device coaxial with a hollow spectacle lens holding shaft.
Consequently, the problem on which the invention is based is to create a spectacle lens machining apparatus in the case of which no particular requirements are placed on the skill and accuracy of an operator when inserting a rough-cast lens which is to be machined into the apparatus, the aim being that the apparatus should be of simple design and reliable in manipulation.
Starting from this formation of the problem, it is proposed in the case of a spectacle lens machining apparatus of the type mentioned at the beginning to provide it with a sensor, which measures the position of the rough-cast lens and its angular position on the holder, in the region between the flap and the spectacle lens holding shaft, and with a control device, constructed as a computer, which takes account, by computer using the sensor data, of the position and angular position of the rough-cast lens in the spectacle lens holding shaft during form grinding of the spectacle lens by means of the machining apparatus.
The invention proceeds from the consideration that the position and angular position of the rough-cast lens in the spectacle lens holding shaft are determined by the position and angular position on the holder, and that as the flap swings-in, the rough-cast lens moves on a geometrically predetermined track, with the result that it suffices to measure the position and angular position of the rough-cast lens on the holder in the region between the starting position of the rough-cast lens on the holder with the flap folded open and the spectacle lens holding shaft before the rough-cast lens is taken over by the spectacle lens holding shaft, and take account of this measured value by computer when machining the spectacle lens.
It is therefore sufficient to mount the rough-cast lens by hand on the holder on the flap with the flap open in a fashion requiring little skill and accuracy on the part of the operator, and then close the flap so that the spectacle lens holding shaft can take over the rough-cast lens, the position and the angular position of the rough-cast lens being measured and taken into account by computer.
The sensor can preferably be constructed as a CCD camera which is arranged on the flap or in the swiveling path of the rough-cast lens on the flap outside or inside the grinding chamber.
When the sensor is arranged on the flap, the position and angular position of the rough-cast lens can be determined directly with reference to the holder and be forwarded to the computer of the control device. In this case, the CCD camera moves with the flap and is located in the machining chamber during the machining of the spectacle lens.
If the sensor is arranged fixed on the housing of the spectacle lens machining apparatus in the swiveling path of the rough-cast lens on the flap outside or inside the machining chamber, it is advantageous to arrange an angle sensor, which is connected to the control device, on a hinge for the flap, with the result that the measurement of the position and the angular position of the rough-cast lens on the holder is always triggered by the angle sensor in a specific angular position which can be related to the position and angular position of the rough-cast lens in the spectacle lens holding shaft.
REFERENCES:
patent: 5588899 (1996-12-01), Gottschald
patent: 5727987 (1998-03-01), Gottschald
patent: 5908348 (1999-06-01), Gottschald
patent: 4414784 (1995-11-01), None
patent: 19527222 (1997-01-0
Gottschald Lutz
Luderich Jorg
Banks Derris H.
Ostrolenk Faber Gerb & Soffen
Wernicke & Co. GmbH
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