Method and apparatus for visualizing a signature mark on a spectacle lens

Abstract

A method and an apparatus serve for visualizing a signature mark on a spectacle lens. In order to identify the signature mark, an illumination light beam is directed onto the spectacle lens, which impinges on the spectacle lens, after impinging on the spectacle lens is reflected at a retroreflector, impinges once again on the spectacle lens, and finally is passed as an observation light beam to a camera. A reflection region of the illumination light beam on the reflector is varied by means of a moved first optical element.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the priority of German patent application DE 10 2011 119 806.0, filed Nov. 25, 2011 and of U.S. provisional patent application No. 61 / 563,661, filed Nov. 25, 2011.BACKGROUND OF THE INVENTION[0002]The invention relates to a method for visualizing a mark or signature mark on a spectacle lens, in which, in order to identify the signature mark, an illumination light beam is directed onto the spectacle lens, which impinges on the spectacle lens, after impinging on the spectacle lens is reflected at a reflector embodied as a retroreflector, impinges once again on the spectacle lens, and finally is passed as an observation light beam to a camera.[0003]The invention furthermore relates to an apparatus for visualizing a mark or signature mark on a spectacle lens, comprising an illumination light source arranged on a first side of the spectacle lens and sewing for generating an illumination light beam, for identifying the si...

AI Technical Summary

Benefits of technology

[0034]If the reflection region on the reflector is moved, then a homogeneous background is produced, from which the signature marks stand out significantly more clearly and thus with higher contrast. The spectacle, lenses to he tested appear uniformly bright during the measurement. However, at the edges of the signature marks scattering occurs to such a great extent that the scattered light no longer meets the retroreflection condition, with the consequence that the signature marks appear dark on a bright background. As a result of the movement of the first optical element and thus of the reflection region on the retroreflector, the structure of the retroreflector blurs and waves, inhomogeneities, contaminants, etc. of the retroreflector itself are no longer disturbing.

[0073]In further refinements of the invention, the illumination light beam and the measurement light beam have different light wavelengths. This measure, too, has the advantage that both light beams can be separated exactly from one another with regard to the electronic further processing. Preferably, the illumination light beam is generated as red light, i.e. in particular in a wavelength range of 650 to 750 nm, and the measurement light beam is generated as green light, i.e. in particular in a wavelength range of 490 nm to 575 nm.

Problems solved by technology

Therefore, it is difficult to identify the position of a signature mark on a spectacle lens during the production process.

What is disadvantageous about this known procedure, in particular during automatic identification of the signature marks, is that the grating is imaged with different magnifications depending on the power of the spectacle lens examined, namely depending on the respective dioptric power of the spectacle lens.

It is therefore necessary, for identifying the signature marks, to implement a considerable complexity with regard to the algorithms used.

Known methods hitherto have not led to totally reliable automatic identification.

However, even with these methods the marks themselves can only be discerned unclearly, with the result that errors are possible in the positioning and orientation of the respective spectacle lens.

This disadvantage is likewise manifested in a reduction of the productivity of the video-assisted, manually actuated stamping machines.

What is disadvantageous about this known procedure is that it can lead to problems in the case of spectacle lenses having very different flexures.

Therefore, for structural reasons it is not possible to arrange the retroreflector very far behind the plane of the spectacle lens in this case.

The known apparatus is therefore relatively complex in terms of operating control.

This can lead to disturbances during the evaluation.

This apparatus has the disadvantage that the marking, depending on the type of lens, is displaced by the local prismatic effect thereof or is demagnified or magnified by the converging or diverging effect of the lens.

However, such movements, particularly if they are to be performed with a high frequency, can be balanced only with difficulty, and so the outlay in terms of apparatus is very high.