Device for mounting a retaining part on an optical surface of an ophthalmic blank

A device for mounting a retaining part on an optical surface of an ophthalmic blank, e.g., before the insertion of the ophthalmic blank into an ophthalmic glass processing machine. The device has at least one viewing unit for parallax-free centering of the ophthalmic blank, at least one retaining device for supporting the ophthalmic blank during centering, and a motion drive for the retaining device for moving the ophthalmic blank from the centering position at the viewing device into a position for mounting the retaining part.

BACKGROUND OF THE INVENTION 
The invention relates to a device for mounting a retaining part on a first 
optical surface of an ophthalmic blank before the ophthalmic blank is 
inserted into an ophthalmic glass processing machine. 
Such retaining parts are required if the second or the other optical 
surface of an ophthalmic blank is to be processed in accordance with the 
required optical values, or if the circumference of the ophthalmic glass 
is to be rimmed in accordance with the shape of a selected spectacle 
frame. 
In order to process the second optical surface of an ophthalmic blank, the 
retaining part must be mounted on an already completely processed first 
optical surface of the ophthalmic blank in a manner which takes account of 
a prescribable preliminary decentering, the position of a reading area, 
and the axial position of a cylindrical or prismatic cut. A similar 
condition also applies in the case of mounting a retaining part for the 
rimming of the ophthalmic blank. Here it is additionally necessary to take 
account of the decentering, that is the positions of the pupils of the 
wearer with reference to the geometric center point of the ophthalmic 
glass openings of the spectacle frame which the spectacle wearer has 
chosen. 
German Patent 42 33 400 from the assignee hereof describes a device for 
parallax free centering of an ophthalmic blank and for applying markings 
and/or for mounting a retaining part before an ophthalmic blank is 
inserted into an ophthalmic glass rim grinding machine. The device 
includes a beam splitter arranged between the eye and the ophthalmic blank 
to superimpose on the image of the ophthalmic blank an image of a template 
or of a spectacle frame opening and of a scale. This device has a bearing 
which is driven by an electric motor and which can be moved up and down. A 
blank holder can likewise be moved up and down and it holds the ophthalmic 
blank on the bearing but permits lateral movements in the bearing plane. A 
proximity detector, which is operationally connected to the drive for the 
bearing and to the blank holder, positions the ophthalmic blank at a 
predeterminable height while the blank is held between the blank holder 
and the bearing. The retaining part to be mounted on the ophthalmic blank 
is mounted on a holder of a pivoted arm, which can be pivoted out and can 
be pivoted into the region of the centered ophthalmic blank that is held 
between the bearing and the blank holder. As a result, the bearing is 
moved upward with the ophthalmic blank and the blank holder until the top 
side of the ophthalmic blank bears against the retaining part and adheres 
to it. This retaining part can be configured as a sucker or an adhesive 
block. Thereafter, the ophthalmic blank with the retaining part fastened 
to it is removed from the device and inserted into an ophthalmic glass rim 
grinding machine. This known device can be used to mount exclusively 
prefabricated adhesive blocks or suckers of small diameter on the 
ophthalmic blank. 
U.S. patent application Ser. No. 08/117,733, filed Sep. 7, 1993, describes 
a further device for mounting a retaining part on one optical surface of 
an ophthalmic blank before it is inserted into a machine for processing 
the second optical surface. The ophthalmic blank is laid with its convexly 
curved first optical surface onto an alignment retaining ring that is 
arranged above a flat LCD screen. The screen shows images of the finished, 
rimmed ophthalmic glass, a reticle and further data required for 
processing the ophthalmic glass. The ophthalmic blank laid onto this fixed 
alignment retaining ring is viewed using a viewing unit and the blank can 
be displaced by hand into a desired or prescribed centering position. 
Thereafter a retaining device in the form of a sucker is lowered onto the 
surface of the ophthalmic blank to be processed and transports the 
ophthalmic blank in the transverse direction to a device for casting a 
plastic retaining part onto the optical surface of the ophthalmic blank. 
The ophthalmic blank is deposited by the retaining device onto a sealing 
ring and is provided from below with the retaining part. This is performed 
such that there is first inserted into a cavity below the sealing ring an 
element of the retaining part which is configured in accordance with a 
receptacle in a machine for processing the optical surface. Then the 
interspace between this element of the retaining part and the optical 
surface of the ophthalmic blank is filled with a thermoplastic material. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a device for mounting a 
retaining part on an optical surface of an ophthalmic blank, by which all 
types of retaining parts can be mounted, and which permits the mounting of 
always similar retaining parts in conjunction with a simple design and 
simple mode of operation, even if the ophthalmic blank is to be given or 
has a prismatic or cylindrical cut. 
A device of the type mentioned above has at least one viewing unit with a 
fixed stop against which the ophthalmic blank is to be laid and the 
viewing unit enables parallax free viewing while centering the ophthalmic 
blank. There is at least one movable retaining device with a bearing for 
the ophthalmic blank. At least one block station is arranged in a plane 
below or above the movable retaining device. A motion drive for the 
retaining device lays the ophthalmic blank held on the bearing against the 
stop into the centering position and from the centering position into a 
position, arranged therebelow or to the side thereof, for mounting the 
retaining part in the at least one block station. 
In contrast with the device in German Patent 42 33 400, the position for 
mounting the retaining part is not situated between the viewing unit and 
the retaining device and above the centering position. It is instead 
arranged below or to the side of the centering position. As a result, it 
is possible to provide a fixed stop on the viewing unit which is intended 
exclusively for centering, but which has no function during mounting of 
the retaining part. The stop can therefore be configured as a simple, 
stable ring, possibly with three pins arranged uniformly around the ring 
opening. As a result, an always constant viewing plane is defined for the 
ophthalmic blank, independently of how the ophthalmic blank is aligned or 
centered. 
If only one position for mounting the retaining part is located below the 
retaining device, it is only necessary for the retaining device to be 
capable of being moved up and down between the centering position and the 
position for mounting the retaining part and also of being pivoted about a 
horizontal axis. 
However, the retaining device can be advantageously displaced transversely 
between a first and a second position for mounting the retaining part, 
making it respectively possible to center an ophthalmic blank and to 
provide a retaining part to a second, already centered ophthalmic blank 
which is in the second position. 
This can be achieved, for example, because two retaining devices are 
arranged kinetically coupled next to one another and can be moved 
alternately into the centering position and the respective position for 
mounting the retaining part. It is possible for the centering position to 
be situated approximately centrally between the two positions for mounting 
the retaining part. 
It is likewise possible to arrange two retaining devices in respective 
positions each for mounting the retaining part, and to arrange the viewing 
unit so that it is capable of moving transversely into each region of a 
respective retaining device. 
It is, however, also possible to arrange a retaining device capable of 
moving alternately into one of two positions for mounting the retaining 
part, and to provide a viewing unit in each of the two positions. 
Finally, it is also further possible to arrange a retaining device and a 
viewing device kinetically coupled and capable of being moved alternately 
into one of two positions for mounting the retaining part. 
The motion drive for the retaining device may be used to raise and/or lower 
the device, respectively as far as the stop on the viewing unit and/or 
into the position for mounting the retaining part. 
If the position for mounting the retaining part is situated below the 
retaining device, the latter can have a pivot drive about a horizontal 
axis, causing the ophthalmic blank received by the retaining device to be 
pivoted upward in order to be brought into the centering position and to 
then be pivoted downward in order to be brought into the position for 
mounting the retaining part. 
It is preferable for the retaining device to have three bearing pins with 
controllable suction heads for holding the ophthalmic blank on the surface 
opposite the optical surface. After alignment or centering of the 
ophthalmic blank, vacuum is applied to the suction heads, for securing the 
ophthalmic blank in place so that during the process, the circumference 
and the already processed optical surface remain completely free. 
If the bearing pins are arranged to be axially displaceable in a resilient 
fashion, the optical surface of the ophthalmic blank always makes contact 
with the stop over its entire area in the centering position, and the 
ophthalmic blank can always be aligned without any problem. 
The retaining device can advantageously comprise a pot shaped carrier with 
an illuminating system and guides for the bearing pins. The pins penetrate 
a ground glass screen and a condenser lens, and there can be a locking 
device for the bearing pins. This locking device holds the bearing pins in 
place in the position which they assume upon centering of the ophthalmic 
blank. As a result, the ophthalmic blank can be moved in this position 
into the position for mounting the retaining part. 
Preferably, the viewing unit, the stop and the retaining device can be 
arranged one above another on a common carriage, and the carriage can be 
moved on a carrier housing alternately into one or the other of the two 
positions for mounting the retaining part. 
In one embodiment, in order to be able both to move the retaining device up 
and down and to pivot it about a horizontal axis, the retaining device has 
axially parallel guide rails. These cooperate with corresponding 
complementary guide rails which are, pivotable about a horizontal axis, on 
parallel retaining arms of the carriage. This enables the retaining device 
to be pivoted and raised and lowered between the centering position with 
an upwardly directed optical surface of the ophthalmic blank and the 
position for mounting the retaining part with an obliquely downwardly 
directed optical surface of the ophthalmic blank. 
Preferably, a device for casting on a wax, plastic or metal alloy retaining 
part can be arranged in the position(s) for mounting the retaining part on 
the optical surface of the centered ophthalmic blank. 
Other features and advantages of the present invention will become apparent 
from the following description of the exemplary embodiments of the 
invention which refers to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
In the exemplary embodiment in accordance with FIGS. 1 to 8, the device has 
a carrier housing 1 with a bevelled front surface on which are arranged 
two spaced apart block stations 2. Each has a central sealing ring 3. An 
arrangement (not represented in detail) is located in the carrier housing 
1 below the block stations 2 for retaining liquid state wax, thermoplastic 
material or a metal alloy. When an ophthalmic blank 16 is placed onto the 
sealing ring 3, the above noted material can be inserted into a mold 
cavity below the ophthalmic blank on the sealing ring 3 and can then be 
cooled there. 
Two parallel guide rails 4 are arranged on a perpendicular or upstanding 
surface of the carrier housing 1. A carriage 5 can be transversely 
displaced along those rails. The displacement can be caused by a geared 
motor 27 which is fastened on the carriage 5 and engages a gear wheel 28 
which in turn meshes with a gear rack 29 on one of the guide rails 4. 
A viewing unit 6 is arranged on the carriage 5. Its optical part can 
correspond to the viewing unit described in German Patent 42 32 400. 
Moreover, parallel retaining arms 7 are arranged on the carriage 5 and 
extend approximately horizontally and parallel to the viewing unit 6 and 
out from the housing 1. A pot shaped carrier 8 is arranged on the end of 
the retaining arms 7. Three resilient, axially displaceable bearing pins 9 
project from one side of the carrier 8. Suction heads 10 are arranged on 
the ends of the pins 9. 
As can be seen in FIG. 7, axially parallel guide rails 11 are fastened at 
the side of the pot shaped carrier 8. The rails 11 cooperate with 
corresponding complementary guide rails 12 on the retaining arms 7. The 
guide rails 12 are pivotable about a horizontal pivot axis 13 extending 
parallel to the guide rails 4. For this purpose, the guide rails 12 are 
mounted in the respective retaining arms 7 with the aid of ball bearings 
24 and are connected to a pivot drive 14 and to a height adjusting drive 
15. The pivot drive comprises a geared motor 20, which is mounted on a 
pivotable arm 7, through a toothed belt wheel 21. A further toothed belt 
wheel 23 is arranged at the pivot axis 13 of the guide rails 12. A toothed 
belt 22 is trained over the toothed belt wheels 21, 23. The height 
adjusting drive 15 comprises a geared motor which is fastened to one of 
the guide rails 12 and which has a gear wheel 25 that meshes with a gear 
rack 26 on the respective guide rail 11. 
In the operating position represented in FIGS. 1 and 2, an ophthalmic blank 
16 can be laid onto the suction heads 10 of the bearing pins 9 such that 
one finally processed optical surface 17 of the ophthalmic blank 16 is 
directed toward the viewing unit 6. Thereafter, the pot shaped carrier 8, 
with the bearing pins 9 and the ophthalmic blank 16 laid onto the suction 
heads 10 is moved up into the position shown in FIG. 3, in which the 
optical surface 17 contacts an annular stop 18 and is positioned by means 
of holders 19 on the viewing unit 6. In this operating position, the 
ophthalmic blank 16 is located in a plane which is defined by the stop 
ring 18 and at which parallax free viewing of a display screen 41 of the 
viewing unit is possible. An image 37 of the ophthalmic blank appears on 
the display screen 41, and a close up viewing area 38 possibly already 
present can likewise be seen. The display screen is preferably configured 
as a transparent LCD screen. It is also possible to image an image of the 
rimmed ophthalmic glass 40 on the display screen 41, as well as to 
represent the position of the possibly decentered optical center point 39, 
the axial position of a prismatic and/or a cylindrical cut. It is also 
possible to mark a preliminary decentering, in order to be able to 
produce, with as small as possible a diameter of the ophthalmic blank, a 
specific ophthalmic glass corresponding to the shape of a selected 
spectacle frame and with the personal optical values of the spectacle 
wearer. The different optical values can be input by means of an input 
keyboard 36 for a conventional control unit (not represented in detail) or 
in another known way, for example by a bar code reader or a diskette. 
As seen in FIG. 8, the pot shaped carrier 8 has on its upper surface a 
condenser lens 30. A ground glass screen 31 is below the lens. Guide 
sleeves 34 for the resiliently axially displaceable bearing pins 9 extend 
through the condenser lens 30 and the ground glass screen 31. 
Each bearing pin 9 is provided with a vacuum or suction connection 33 to 
apply vacuum to the suction heads 10. 
Referring to FIG. 7, after the ophthalmic blank has been aligned and 
centered in the position shown in FIG. 3, a clamping ring 32 is actuated. 
Vacuum is applied to the underside of the ophthalmic blank 16 via the 
vacuum connections 33. The blank 16 is held in place in the position 
specified in the centering position. An incandescent lamp 35 arranged in 
the pot shaped carrier 8 illuminates the ophthalmic blank 16 through the 
ground glass screen 31 and the condenser lens 30 in such a way that the 
ophthalmic blank is clearly visible, including a close up viewing area, 
which is possibly present, on the display screen 41 of the viewing unit 6. 
After the blank is centered, the pot shaped carrier 8 is lowered into the 
position shown in FIG. 4 by actuating the height adjusting drive 15. The 
carrier is subsequently pivoted into the position shown in FIG. 5 by 
actuating the pivot drive 14, and it is lowered into the position shown in 
FIG. 6 by renewed actuation of the height adjusting drive 15. As a result, 
the ophthalmic blank 16 is held sealed off on the sealing ring 3 together 
with its optical surface 17. In this position, wax, or thermoplastic 
material or a metal alloy is inserted into the cavity below the ophthalmic 
blank 16 and between the sealing ring 3 where that material cools down. 
During the cool time, the carriage 5 can already be moved with the viewing 
unit 6 and the retaining device, comprising the pot-shaped carrier 8, the 
bearing pins 9 and the suction heads 10, transversely into the region of 
the second block station 2, where the same operation of centering and 
mounting a retaining part can proceed. 
FIGS. 9 and 10 show two further embodiments of the device which have two 
block stations and two retaining devices 8, 9, 10 rather than one, but 
have only one viewing unit 6. 
In the embodiment in FIG. 9, the retaining devices 8, 9, 10 are arranged on 
a common carriage 42 which can be moved transversely on guide rails 43. In 
the position represented, one retaining device 8, 9, 10 is located below 
the viewing unit 6, that is to say in the centering position, while the 
other retaining device 8, 9, 10 is located above one block station 2, that 
is to say in the position for mounting a retaining part. Thus, while one 
ophthalmic blank 16 is being aligned and centered in the centering 
position, another ophthalmic blank 16 is being held on the sealing ring 3 
of the block station 2 and is being provided with a cast on retaining 
part. 
The ophthalmic blank 16 placed onto the sealing ring 3 can be held in place 
by means of the device in FIG. 9 until the cast on retaining part has 
cooled down and solidified sufficiently in order to be removed from the 
mold. During this time, a second ophthalmic blank 16 can be aligned and 
centered in the centering position. 
After termination of the mounting of the retaining part and of the 
alignment and centering, the two retaining devices 8, 9, 10 are displaced 
to the right by means of a motion drive acting on the carriage 42. This 
causes the aligned and centered ophthalmic blank 16 to be placed onto the 
sealing ring 3 of the second block station 2, enabling another ophthalmic 
blank 16 to be aligned and centered. 
In this embodiment, the distance between the retaining devices 8, 9, 10 is 
half the distance between the two block stations 2, and the viewing unit 6 
is arranged approximately centrally above the two block stations 2. 
FIG. 10 shows two block stations 2 and over each of them there is a 
respective retaining device 8, 9, 10. However, these retaining devices 8, 
9, 10 can only be pivoted and moved up and down, but cannot be moved 
transversely. Instead, the viewing unit 6 is arranged on a carriage 44 
which can be moved to and fro along guide rails 45 on the carrier housing 
1 and transversely between the two block stations 2. In this embodiment 
also, an ophthalmic blank 16 can be aligned and centered in the region of 
one block station, while a further ophthalmic blank 16 is lowered onto the 
sealing ring 3 of the second block station 2 where it is provided with a 
retaining part. 
In all these embodiments, the block stations not only can be set up to cast 
on a retaining part, but can also have holders for prefabricated adhesive 
blocks or suckers onto which the aligned and centered ophthalmic blanks 
can be lowered and in this way connected thereto. 
Furthermore, particularly for the embodiment of FIG. 9, it is possible to 
arrange the block stations 2 in the same plane as the stop ring 18 on the 
carrier housing 1. It is then not necessary to provide pivoting movement 
for the holding device 8, 9, 10, but only up and down movement. 
Although the present invention has been described in relation to particular 
embodiments thereof, many other variations and modifications and other 
uses will become apparent to those skilled in the art. It is preferred, 
therefore, that the present invention be limited not by the specific 
disclosure herein, but only by the appended claims.