BE1017286A6 - DEVICE FOR VISIBLEING A BRAND ON A GLASS OF GLASSES. - Google Patents

Abstract

Apparatus for rendering visible a spectacle lens (16) provided with a mark (18) and placed on a support (12), with a lighting source (20) for producing a lighting beam (22) with a camera (36) for receiving an observation light beam (34), with first optical means (24) for guiding the light beam of illumination to and through the spectacle lens and through the mark and with second optical means for guiding the illuminating light beam which has passed through the eyeglass lens as an observation light beam to the camera, the spectacle lens being coated with a phototropic coating (19 ) and provided below the coating of the mark, the light source of illumination being a point light source.

Description

The invention relates to a device for making visible a spectacle lens provided with a mark, comprising a spectacle lens placed on a support, a light source of illumination. for producing a light beam of illumination, a camera for receiving an observation light beam, first optical means for guiding the light beam of illumination from the light source to the spectacle lens and for passing through the spectacle lens as well as the mark (18; 52) and second optical means for guiding the illuminating light beam having passed through the eyeglass lens as an observation light beam towards the camera.

A device of the type mentioned above is known from DE 103 33 426 A1.

Eyeglass lenses, in particular so-called progressive lenses, are provided with marks the position of which is detected and processed during the production of the spectacle lens to tighten, machine, mark and check the spectacle lens in a correct position and finally for the place in the glasses of the end consumer. Marks are permanently applied to spectacle lenses and in fact by a diamond etching process, by shaping when molding glasses of plastic glasses or by laser marking.

In the context of the present application for "spectacle lenses", it is also intended to include contact lenses and other comparable optical components.

So that the wearer of glasses is not disturbed by the marks when using the glasses, these marks are made so as to be identifiable only in very special light conditions. Identifying the position of a mark on a spectacle lens during the production process is therefore difficult.

This is particularly true when the spectacle lens is provided with a phototropic coating. Such spectacle lenses are also referred to as HIP (High Index Phototropic) in the technical field. Phototropic coatings of the type of interest here are relatively thick. The layer thickness is about 30 μm, while the other layers of refinement (anti-reflective layers, etc.) have a layer thickness of the order of only about 2-3 μm. The marks are applied on the lens bodies before the ennoblement. They are therefore covered by the ennobling layers applied later. While for the usual thin layers of ennoblement, this poses no significant problem for the identification of the mark, there is a problem when the mark is covered by a thick phototropic layer. As a result, the mark is in particular optically erased, that is to say that the edges of the mark are blurred. It only appears as a phenomenon of low frequency unlike a situation with only thin layers.

For control of progressive lenses at the point of reference of distance vision and near vision, it is necessary to measure the action of progressive lenses at coordinates determined on the spectacle lens according to the applied marks. For manual measurement or automatic measurement, the marks must be made visible. This is done in the context of known methods and devices using rhombic grids or striped patterns that have a fuzzy configuration and whose light / dark transitions make the mark identifiable.

The disadvantage of this known procedure, in particular during the automatic identification of the marks, lies in the fact that the grid is imaged with a different magnification depending on the action of the spectacle lens studied, namely according to the dioptric action in question of glasses glass. This is why it is necessary for the identification of the mark to carry out a considerable work with regard to the algorithms used. The known methods have not led so far to a fully reliable automatic identification. Therefore, in current practice, it is necessary that a specially trained workforce intervenes in the production process and corrects the errors detected even in automated verification facilities.

But the situation is similar, even when the marks are identified through a manual audit operation as part of a production process. In this case, different lighting is used to make the marks visible according to the marking method used. In known devices, this is done by manual switching of lighting units. Even with these manual processes, however, the marks themselves are only vaguely identifiable, so that errors in the positioning and orientation of the glasses lens in question are possible. This also applies in particular to the time available for the identification of the mark. For these reasons, it is necessary, in particular for glasses of plastic glasses, to hand mark spectacle lenses by means of a felt or the like ("to draw points") before the actual identification of brand, which requires work and extra time.

Corresponding considerations also apply to another field in the context of the machining of such spectacle lenses, namely for stamping machines which, according to the state of the art, also require the assistance of an operator. The latter observes the spectacle lenses on a screen in order to manually correct mark positions in the system that are not automatically identified, for example by means of an input with the trackball. This disadvantage also results in a decrease in the productivity of manually operated, video-assisted marking machines.

Document DE 103 33 426 A1 cited at the beginning discloses a device that overcomes to a certain extent the problems mentioned above in that the light beam of illumination is guided through the spectacle lens, is reflected on the the opposite side of a moving retroreflector, is guided again through the spectacle lens and brought as an observation light beam to the camera. When the retroreflector is moved, a more homogeneous background is generated, the background of which the marks stand out much more clearly and therefore in a more contrasted manner than previously known. The glasses glasses to check appear uniformly clear during the measurement. On the edges of the mark, however, appears a dispersion so strong that the scattered light no longer fulfills the condition of retroreflection with the result that the marks appear dark on the background light. Thanks to the movement of the retroreflector, its structure becomes blurred and the undulations, inhomogeneities, dirt, etc., of the retroreflector itself are no longer disturbing.

This known procedure has been proven for normal spectacle lenses without finishing layers or with thin layers of finishing (a few μm thick). However, it reaches its limits for the reasons mentioned above when the spectacle lens is coated with thick layers (approximately 30 μm thick), such as phototropic layers.

The invention therefore has the task of improving a device of the type mentioned at the beginning so that the disadvantages mentioned are avoided. In particular, it is possible to also treat spectacle lenses with thick layers during a production process, in the sense that on the one hand the applied marks will be identified in the right place, but that on the other hand A measurement of the spectacle lens as part of this same process and also in the same device will be possible. All this must be done with as simple a means as possible in terms of apparatus and process.

In the case of a device of the type mentioned at the beginning, the problem is solved according to the invention because the spectacle lens is coated with a phototropic coating and is provided with the mark below the coating, and the fact that the light source of illumination is a point light source.

The problem underlying the invention is completely solved in this way.

The use of a point-shaped light source (called an "artificial star") has the consequence that low-frequency disturbances are identifiable. The identifiable image of the marks is therefore sharper in the edge region.

In a preferred embodiment of the invention, the point light source has, with respect to the mark, an aperture ratio of less than 1/200, preferably less than 1/500.

This measure has the advantage that an optimal compromise between ideal spot lighting apparatus and a practically feasible lighting fixture can be found. In a practical embodiment of an opening ratio of 1/500, it is possible, for example, to use a high-efficiency light-emitting diode with a selective diaphragm, which has a diameter of 1 mm and a distance of 500 mm from the surface. glasses of glasses provided with the mark.

It is further preferred that the point light source has a wavelength at or outside the visible region, preferably less than 400 or more than 750 nm.

This has the advantage that stray and ambient light can be conveniently removed by a filter on the receiver side.

A particularly good effect is furthermore obtained when a video signal generated in the camera from the observation light beam is detached by contrast from the finished neighborhoods by at least one convolution operation. In doing so, the high place frequencies will be more strongly detached than the low place frequencies, for example due to a differentiating effect.

The video signal produced from the observation light beam in the camera can, according to the invention, be used for different purposes. On the one hand, it can be used to determine the brand through brand recognition. On the other hand, it can be used to determine a position of the spectacle lens on a support and then to determine a dioptric action of the spectacle lens.

According to the invention, the different paths of the beam can be gathered in whole or in part to be able to implement the method in a space as small as possible.

In a first variant, the illumination light beam is integrated in the trajectory of the observation light beam. In a second variant, the measurement light beam is integrated in the trajectory of the observation light beam. In a third variant finally, the measurement light beam is integrated in the path of the light beam of illumination.

This is done in embodiments of the device according to the invention preferably through corresponding beam splitters or other suitable optical means, for example pierced mirrors.

In relation to the beam splitter used, it is preferred to provide a light trap for a fraction of the light beam concerned which passes through the beam splitter.

When a beam splitter is provided for integrating the illumination light beam into the path of the observation light beam, this is preferably done in such a way that an entrance pupil of the camera and an exit pupil of the lighting source are combined with this beam splitter.

In other preferred embodiments of the invention, the illuminating light beam and the measuring light beam are produced with different wavelengths of light.

This measurement also has the advantage that the two light beams can be separated exactly from each other with respect to the subsequent electronic processing.

The lighting light beam is produced as red light and the measuring light beam is produced as green light.

In addition, it is preferably possible for the measuring light beam falling on the sensor to be guided through a filter which acts as a stop filter for the light wavelength of the illuminating light beam.

This measurement also helps to separate the two beam paths from each other.

The retroreflector may finally be configured flat or bent.

Other advantages emerge from the description and the accompanying drawing.

It is understood that the features mentioned above and the characteristics which are yet to be explained below may be used not only in the combination indicated but also in other combinations or alone, without departing from the scope of the present invention. .

Exemplary embodiments of the invention are shown in the drawing and will be explained in more detail in the description which follows.

Fig. 1 shows an extremely schematic side view of a first exemplary embodiment of a device according to the invention, and

Fig. 2 shows a side view also schematized of a second embodiment of a device according to the invention, namely a measuring device of a focometer index, optical means being further provided for measuring a glass of glasses.

In Figure 1, 10 generally denotes a first embodiment of a device according to the invention.

There is provided in the device 10 a support 12 with a central opening 14. On the support 12 and above the opening 14 is a spectacle lens 16.

As can be seen in the enlarged section in FIG. 1, the eyeglass lens 16 is provided with a mark indicated by 18. The mark is applied in the surface of the eyeglass lens 16. The spectacle lens 16 is furthermore provided with a thick coating 19, particularly phototropic, which covers the mark 18. The thickness of the coating 19 is about 30 pm.

A lighting light source 20 is preferably oriented perpendicularly to the optical axis of the spectacle lens 16 which coincides, in the example shown, with the optical axis 21 of a camera 36. The illumination light source is a point light source. It has with respect to the upper surface of the bezel glass 16 in Figure 1 an opening ratio of less than 1/200, preferably less than 1/500. When the illumination light source 20 is formed by a high efficiency light emitting diode (for example, of the SFH4230 type from Osram) with a selective diaphragm placed in front of it, the diameter of the diaphragm can be 1 mm and the distance from the The diaphragm with respect to the surface of the spectacle lens 16 provided with the mark 18 may be 500 mm for an opening ratio of 1/500.

The light source of illumination preferably operates at a wavelength which lies outside or at the margins of the visible field and which is therefore for example less than 400 or more than 750 nm.

The illumination light source 20 emits an illumination light beam 22. It arrives on a beam splitter 24, for example a partially transparent mirror, and is reflected there in the direction of the optical axis 21 of the beam. The camera 36. A fraction of the illumination light beam 22 emerging from the illumination light source and passing through the beam splitter 24 is absorbed by a light trap 26 which is arranged behind the beam splitter 24.

The illumination light beam 22 passes through the spectacle lens 16 and arrives on a retroreflector 30 which, in the representation according to FIG. 1, is arranged below the spectacle lens 16. The retroreflector 30 is provided with a retroreflective coating 32 It can also be configured as a retroreflective sheet that is usually commercially available or as a retroreflector with regularly arranged triple mirrors or triple prisms with a reflective layer.

The illuminating light beam 22 reflected by the retroreflector 30 again crosses - in the opposite direction - the spectacle lens 16 and is then directed as observation light beam 34 towards the camera 36, for example a CCD camera. The camera 36 is focused on the spectacle lens 16 and produces an image of the spectacle lens 16 in which the mark 18 is visible in front of the background of the retroreflector 30.

The retroreflector 30 is connected by an active connection indicated in an extremely schematic manner, in the example shown a drive shaft, to a drive motor 38. The drive motor 38 rotates the retroreflector 30 about an axis vertical which is preferably aligned on the axis 21 of the camera and on the axis of the illumination light beam 22. This is illustrated in Figure 1 by the arrow 39.

In the embodiment shown in Figure 1, the retroreflective coating 32 is formed continuously in the region of the vertical axis of rotation of the retroreflector 30. For this reason, a pattern which however is only slightly disturbing in practice can, therefore, remain identifiable in the region of the axis of rotation and in a small circular neighborhood in adverse circumstances, it should be indicated already at this point that the retroreflector 30 can also, for this reason, be configured in the form of a circular ring, as is the case for the embodiment of Figure 2 which remains to be explained below.

Instead of rotating the retroreflector 30 in its entirety about a vertical axis, it can also be oscillated linearly and transversely to the axis 21. When, in this case, retroreflectors are used with a uniform pattern of retroreflective elements, care must be taken to give an appropriate direction to the linear oscillatory movement with respect to the pattern.

Finally, it is also possible in another variant to make the retroreflector perform a parallel rotary translation similar to the oscillating movement of a grinding disc of an oscillating grinder.

On the whole, it is essentially during the movement of the retroreflector 30 that the regular structures of the retroreflector 30 and a dirt adhering therein if necessary fade in motion blur. It has already been mentioned that the main components of the movement of the retroreflector 30 must essentially run transversely to the optical axis 21 of the camera 36.

For the retro-reflective coating 32 of the retroreflector 30, a uniform pattern of individual elements, for example triple prisms or triple mirrors arranged in a uniform manner, is preferably used. It is then useful to couple the movement of the retroreflector 30 to the vertical synchronization pulses of the camera 36.

The circuit shown in FIG. 1 is used for this purpose. The circuit consists of a control device 40 which is connected by a first line 41 to the camera and by a second line 42 to the drive motor 38. The electronic control device 40 in turn gives instructions to the motor 38 via a third line 43.

The vertical synchronization pulses of the camera 36 are transmitted to the electronic control unit 40 by the first line 41. The motor 38 provides by the second line 42 coding pulses which are compared in the electronic control unit 40 with the vertical synchronization pulses. A control signal for the current or voltage of the drive motor 38 that is transmitted through the third line 43 is derived from this comparison. The adjustment can, in this case, have the effect of synchronizing the speed of rotation, that is to say that the rotational speed of the drive motor 38 is adapted to the frequency of the vertical synchronization pulses. However, a phase-locked coupling is also particularly preferred, which ensures a predetermined phase position between the periodic movement of the driving motor 38 (for example the rotary movement) and the vertical sync pulses of the camera 36.

By virtue of the use of a moving retroreflector 30, the background, in front of which the spectacle lens 16 is imaged in the camera 36, is homogeneous. This avoids the disadvantage of known arrangements in which another fuzzy structure is still superimposed on the mark to be identified, a structure that can even have the order of magnitude of the mark to identify. When, on the other hand, the retroreflector 30 is moved in the manner described, a homogeneous basic image can be extracted during image processing. This is not possible with known devices because the inhomogeneous background pattern is reproduced in different sizes depending on the difference in curvature of the spectacle lenses.

It is particularly advantageous when viewing the contrasting image that the video signal of the camera is furthermore passed through a contrast enhancement device. This leads, for example, to an operation of local convolution of gray values with a kernel function that has differentiation characters in several directions. Details on this can be found in DE 103 33 426 A1 cited at the beginning.

In the embodiment according to Figure 2, 44 designates a device, namely a focometer, with a housing 46 tight to light.

In the embodiment according to Figure 2, a device 44 having an opening 48 is shown. A spectacle lens is designated 50. The spectacle lens 50 is on a support 54 and corresponds concretely to the spectacle lens 16 of FIG. 1, that is to say that it is also provided with a thick lens. phototropic coating (not shown in Figure 2).

In addition, only a mark 52 is shown in Figure 2. In reality, however, there are two marks that are at a predefined distance above and below the plane of the drawing. The two marks define by their position the location of the spectacle lens 50 where a physical property, for example the power of the spectacle lens 50, must be measured. A measuring light beam 64 is directed at this location. For this purpose, the eyeglass lens 50 is placed by an operator on a tubular support 54 and is manually oriented thereon with respect to the marks 52. In this case, it may be a generally commercially available focometer. For the measurement, the spectacle lens 50 is positioned in this focometer so that the contrasting display marks 52 are placed at a predetermined location in the image of the camera. The marks are not at the point of measurement but in a geometric relation determined with respect to it.

The housing 46 has only on the right side of Figure 2 the opening 48 accessible from the outside. In this opening 48 there is a housing for spectacle lens 50 which is provided with marks 52.

Below the eyeglass lens 50 is a circular ring retroreflector 56, indicated only schematically herein, which can be rotated by means of a drive means (not shown), as indicated by arrow 58. On this point, what has been explained above for the embodiment according to Figure 1 also applies here.

In the housing 46 is an upper chamber 60 at the left end of which a measuring light source 62 is disposed. The measurement light source 62 emits a measuring light beam 64. This first passes through a first color filter 66 and then a diaphragm 68 before being deflected downwards in a prism 70 or a corresponding mirror. The measuring light beam 64 passes through a prismatic compensator 72 and a hole in a pierced mirror 73 and meets the upper side of the spectacle lens 50. It passes through the spectacle lens 50 as well as the support 54 and then passes through a second filter color 74 provided in the preferred embodiment of the invention before encountering a sensor 76.

In a central chamber 77 of the housing 46 is a lighting light source 78 three embodiments of which will be further explained below on the basis of Figures 3 to 5.

The illumination light source 78 emits a light illumination beam 79. This first arrives on a deflection mirror 80 and then on a semi-transparent mirror acting as beam splitter 81. A fraction of the light beam The illumination beam 79 passing through the beam splitter 81 is absorbed by a light trap 75 which is disposed behind the beam splitter 81. The illumination light beam 79, however, is essentially deflected to the right by the beam splitter. 81 to meet the prism 82 or a mirror that deflects the illumination light beam 79 downwards. After a new deviation by a deflection mirror 83, the illuminating light beam 79 passes through a window 84 of the aperture 48 and encounters the pierced mirror 73 which again deflects the illumination light beam 79 downwards where it meets the spectacle lens 50 and illuminates the mark 52.

The illumination light beam 79 reflected by the spectacle lens 50 or the mark 52 then forms an observation light beam 85 which first runs upwards and arrives via the pierced mirror 73, the mirror of FIG. deviation 83, the prism 82 and the beam splitter 81 to another prism 86 and or a corresponding mirror which deflects the observation light beam 85 downwards where it reaches via a lens 87 to a CCD camera 88. prism 86, the lens 87 and the CCD camera 88 are in a left chamber 89 of the housing 46.

The entrance pupil of the objective 87 and the exit pupil of the illumination light source 78 are conjugated to one another with respect to the beam splitter 81.

The device 44 according to FIG. 2 operates as follows:

In a measuring circuit, the measuring light beam 64 is emitted in the manner described by the measuring light source 62 on the spectacle lens 50, passes therethrough and reaches the sensor 76. Physical properties of the spectacle lens can be measured this way. To better differentiate it from the illuminating light beam 79 or the observation light beam 85, the measuring light beam 64 is emitted at another wavelength, for example as a green light. For this purpose, the first color filter 66 is made as a green filter. However, the second color filter before the sensor 76 has the function of a stop filter which does not allow other light wavelengths to pass, in particular those of the illumination light source 78. this way that another light, with the exception of the measuring light beam 64, arrives on the sensor 76.

At the same time, the illumination light beam 79 is directed in the manner described by the illumination light source 78 on the eyeglass lens 50 to illuminate the mark 52. The reflected image of the mark 52 then reaches so much light observation beam 85 to the CCD camera 88 and is processed from there as a video signal.

While this is going on, the retroreflector 56 below the eyeglass lens 50 is set in motion (arrow 58) and in the manner already described, namely rotatively around the carrier or in a parallel rotational translation.

The frequency of one of the aforementioned periodic movements of the retroreflector 56 is then again chosen so that it is adapted to a reading frequency of the camera 88.

It is also understood here that an improvement of the contrast by convolution operations of the type explained above can be obtained.

A measurement of a physical parameter of the spectacle lens 50 can be performed, instead of or in addition to the sensor, by evaluating the video signal of the CCD camera 88.

In general, however, efforts are made to decouple the measuring circuit and the lighting / observation circuit from one another.

Claims (16)

Apparatus for rendering a spectacle lens (16; 50) with a mark (18; 52) visible with a spectacle lens (16; 50) placed on a support (12; 54) with a source illumination light (20; 78) for producing a light illumination beam (22; 79) with a camera (36; 88) for receiving an observation light beam (34; 85) with first optical means (24; 73, 80, 81, 82, 83) for guiding the illumination light beam (22; 79) from the light source (20; 78) to the spectacle lens (16; 50) and through the spectacle lens (16; 50) and through the mark (18; 52), and with second optical means (82, 83, 85, 86) for guiding the illumination light beam (22; 79) which has passed through the spectacle lens (16; 50) as an observation light beam (34; 85) to the camera, characterized in that the spectacle lens (16; 50) is coated with a phototropic coating (19) and is provided with use of the coating (19) of the mark (18; 52) and in that the illumination light source (22; 79) is a point light source. 2. Device according to claim 1, characterized in that the point light source has with respect to the mark (18; 52) an opening ratio of less than 1/200, preferably less than 1/500. 3. Device according to claim 1 or 2, characterized in that the point light source has a wavelength at the edge or outside the visible field, preferably less than 400 or more than 750 nm. Device according to one or more of claims 1 to 3, characterized in that the illumination light source (20; 78) is arranged on a first side of the spectacle lens (16; 50), in that a reflector (30; 56) is disposed on the side of the spectacle lens (16; 50) opposite the first side, and in that the reflector (30; 56) is connected to a drive motor (40) for movement (42). 58) the reflector (30; 56). 5. Device according to claim 4, characterized in that the reflector (30; 56) is configured as a retroreflector. Device according to one or more of claims 1 to 5, characterized in that a measuring light source (62) is provided which is architecturally different from the illumination light source (78) for producing a measuring light beam ( 64) for a measurement of a physical property of the spectacle lens (50), a sensor (76), third optical means (54, 66, 68, 70, 72) for guiding the measuring light beam (64) of the measurement light source (62) to the spectacle lens (50) and spectacle lens (50) to the sensor (76). Device according to Claim 6, characterized in that the measuring light source (62) and the illumination light source (78) as well as the first optical means (73, 80, 81, 82, 83) and the third optical means (73, 80, 81, 82, 83) and the third optical means (54, 66, 68, 70, 72) are each architecturally different units. 8. Device according to one or more of claims 1 to 7, characterized in that a beam splitter (24; 81) is provided for integrating the illuminating light beam (22; 79) into the path of the light beam. observation (34; 85). 9. Device according to claim 8, characterized in that a light trap (76; 75) is provided for a fraction of the illuminating light beam (22; 79) passing through the first beam splitter (24; 81). Device according to claim 8 or 9, characterized in that an entrance pupil of the camera (36; 88) and an exit pupil of the illumination light source (20; 78) are arranged in a conjugated manner. relative to the beam splitter (81). Device according to one or more of claims 1 to 10, characterized in that an optical means (73) is provided for integrating the measuring light beam (64) into the path of the observation light beam (85). Device according to one or more of claims 1 to 11, characterized in that an optical means (73) is provided for integrating the measuring light beam (64) into the path of the illuminating light beam (79). 13. Device according to claim 12, characterized in that the light source of illumination (78) has means which diaphragment the light beam of illumination (79) at least in the zone of incidence of the measuring light beam (64). ) on the spectacle lens (50). Device according to one or more of claims 1 to 13, characterized in that the illumination light source (78) and the measuring light source (62) emit light beams (64, 79) of light wavelength different. 15. Device according to claim 14, characterized in that a filter which acts as a stop filter for the light wavelength of the illuminating light beam (79) is placed upstream of the sensor (76). Device according to one or more of Claims 1 to 15, characterized in that the reflector is curved.