GB2138564A

GB2138564A - Instrument for Discriminating Central Thicknesses of Lenses

Info

Publication number: GB2138564A
Application number: GB08405051A
Authority: GB
Inventors: Fumio Onoki; Sachio Yamakawa; Ken Tsukamoto
Original assignee: Hoya Lens Corp
Current assignee: Hoya Lens Corp
Priority date: 1983-03-15
Filing date: 1984-02-27
Publication date: 1984-10-24
Also published as: GB8405051D0

Abstract

An instrument for discriminating central thicknesses of lenses comprises a plurality of plates 3-A, 3- A', 3-B, 3-B', 3-C, 3-C', 3-D, and 3-D' each having a different thickness and supporting members 1 and 2 to support these plurality of plates whereby, before filing and processing the edge of a lens, a central thickness of the lens after processing can be actually felt and seen. The relevant thickness may be first determined from data tables provided on the support members 1. <IMAGE>

Description

SPECIFICATION Instrument for Discriminating Thickness of Lenses The invention relates to an instrument which is used in the selection of the kinds of frames and lenses to be used for spectacles, and especially to an instrument which is suitable to enable a user actually to feel the different shapes, dimensions and centre thicknesses of the lenses of a pair of spectacles to be made in accordance with a given prescription and to fit a given spectacle frame by means of practical standard models before the lenses are actually made up.

In the adjustment of spectacles, when the number of kinds of spectacle frames (hereinafter referred to simply as frames) and the number of kinds of spectacle-lenses (hereinafter referred to simply as lenses) were small, as was formerly the case, the ranges of choice were narrow and, accordingly, the number of possible combinations of frame and lenses was relatively small. Now, however, since there are a wide variety of frame shapes and materials for lenses, the number of possible combinations of frame and lenses becomes large and there are a variety of and many kinds of such combinations. In some cases, the final states of different pairs of glasses made according to the same prescription may differ considerably. For example, as shown in Fig. 3, there is a difference between the central thicknesses 6 and 7 of two finished lenses 4 and 5 of the same power.The lens 4 is made by a method in which after a lens having a standard diameter of, say, 60 or 70 mm has been made to a given optical power, the peripheral edge portion of the lens is filed and processed to the shape and size of the frame (hereinafter, called the present method). The lens 5 is made by a method in which, after a lens has been made to the given optical power so that the central thickness of the finished lens is as small as is practical, the peripheral edge portion of the lens is ground and processed to the size and shape of the frame (hereinafter called the METS (Minimum Edge Thickness System) method). The central thicknesses of lenses also differ depending upon the materials of the lenses; the higher the refractive index of the material, the thinner the lens can be for a given refractive power.For example, the thicknesses of lenses made of glass and of an optical resin differ depending upon their different physical properties. In addition, the central thicknesses of the lenses also differ depending upon the shapes and dimensions of the frames.

Conventionally, as an aid to estimating the thickness of the finished glasses while selecting lenses and a frame, a table was made and a numerical value was read out from the table and this value was used as a reference for enabling one to estimate the thicknesses of the lenses as they would be when finished. However, it is difficult to visualise the thickness unless one can actually see or feel it.

It is an object of the present invention to provide an instrument with which, when selecting spectacles, it is possible to discriminate with actual feeling by seeing directly, and preferably also by touching, the varying degrees of central thickness that the lenses would have after they had been made up, as a function of the different lens materials, frame shapes, and methods of processing lenses (present method and METS method), before such adjustment and processing have actually been carried out.

The invention provides a kit or device for assessing the central thicknesses of lenses, comprising: means for deriving or enabling a user to derive the thickness of the centre of a lens from data indicating at least one of the size, shape, material, and optical power of the lens and/or other relevant data; and means for providing a direct visual and/or tangible display of the thickness of the centre of the lens.

The invention also provides a kit or device for assessing thicknesses of lenses, comprising: means for deriving or enabling a user to derive the thickness of a selected part of a lens from data indicating at least one of the size, material, and optical power of the lens, and/or other relevant data, according to a plurality of methods of deriving the form of the lens from the data; and means for providing a direct visual and/or tangible display of the thicknesses of the selected part of the lens when the form of the lens is derived by the different methods.

One form of instrument constructed in accordance with the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 shows a front view of the instrument; Fig. 2 shows a side elevation view of the instrument; Fig. 3 is a diagram illustrating the difference that may occur between the thicknesses of lenses processed by different methods; Figs. 4A, 4B, 4C, and 4D are diagrams illustrating standard shapes for spectacle-frames; Fig. 5 is a diagram illustrating the positions on a spectacle-frame at which dimensions are measured; Figs. 6, 7, 8 and 9 are parts of a table indicating the central thicknesses of convex lenses; and Fig. 10 shows the assembly of the table from the parts shown.

Referring now to Figs. 1 and 2 of the drawings, a box 1 is a substantially rectangular box-shaped casing constituted by four side plates 1 A, 1 B, 1 C, and 1 D which may be made of wood or plastics or another suitable material. A holding axis of rod 2 is fixed to one side plate 1 D and a plurality of standard models 3 are attached to this rod 2 to display in a form that can be sensed both by sight and by tough the different central thicknesses of lenses to be made depending upon the differences in frame shapes (standard frame shapes shown in Figs. 4A to 4D), lens materials and methods of processing lenses. In Fig. 1, lenses of the frame shape shown in Fig. 4A are indicated by block I, in which a model 3-A represents a lens made by the present method, while a model 3-A' represents the corresponding lens made by the METS method.In the same manner as above, the models 3-B and 3-B' in block II represent lenses of the frame shape shown in Fig. 4B; the models 3-C and 3-C' in block Ill represent lenses of the frame shape shown in Fig. 4C; and the models 3D and 3-D' in block IV represent lenses of the frame shape shown in Fig. 4D. It is possible from Fig. 1 to discriminate by eye the difference between the central thicknesses of the lenses to be made by the present method, represented by the models 3-A, 3-B, 3-C, and 3-D, and the thicknesses of the lenses to be made by the METS method, represented by the models 3-A', 3-B', 3-C', and 3-D'. These standard models 3 may be made from, for example, a plastics material or the like.

For easy observation of these standard models 3 from the side, the height of the side plates 1 A and 1 C is lower than that of the side plate 1 D to which the rod 2 is fixed and the side plate 1 B opposite it, the bottoms of the models 3 being above the tops of the side plates 1 A and 1 C.

The table shown in Figs. 6, 7, 8 and 9 is attached to one or all of these side plates; this table shows the lens materials, prescription values, frame shapes (FRAME) and dimensions (SIZE), and central thicknesses of the convex lenses to be made by the present and METS methods. With respect to (FRAME (SIZE)) representing the frame shapes and dimensions which are used in the table, for example, G07063 56-14 written in the section of UV (crown lens) of S.V. (single focus) for a male in the table will be described. G07063 indicates the standard shape of the frame, in this case, the shape of Fig. 4A. For 56-14, as shown in Fig. 5, 56 denotes a lateral dimension 8 of the part of the frame surrounding one lens and 14 represents a dimension 9 of the space between the frames on either side of the nose. The table is assembled as shown in Fig. 10.

For example, assuming that the UV (crown lens) of S.V. (single focus) for a maie is used and the prescription values are SPH; +2.00, CYL; +2.00, AXIS; 1800, D/PD; 64.0 and that the frame shape and dimensions are G07063 56-14, there are indicated that a lens to be made by the present method (i.e, conventional method) would have a central thickness (C.T.) of 4.9 mm and a weight of 57.6 g; on the other hand, a similar lens to be made by the METS method would have a central thickness of no more than 3.6 mm and a weight of remarkably much less at only 40.9 g. In addition, the differences in C.T. and weight between the lenses made by the two methods are also shown. In this way, after the central thickness of the lens has been obtained as a numerical value, the previously mentioned plurality of standard models 3 are used to perceive directly the thickness of the lens to be made by sight and/or by touch.

Although the case of convex lenses has been described in the above embodiment, it is also possible to discriminate the central thicknesses of lenses in substantially the same manner as in the case of concave lenses.

Claims

1. A kit or device for assessing the central thicknesses of lenses, comprising: means for deriving or enabling a user to derive the thickness of the centre of a lens from data indicating at least one of the size, shape, material, and optical power of the lens and/or other relevant data; and means for providing a direct visual and/or tangible display of thickness of the centre of the lens.

2. A kit or device for assessing thicknesses of lenses, comprising: means for deriving or enabling a user to derive the thickness of a selected part of a lens from data indicating at least one of the size, material, and optical power of the lens, and/or other relevant data, according to a plurality of methods of deriving the form of the lens from the data; and means for providing a direct visual and/or tangible display of the thicknesses of the selected part of the lens when the form of the lens is derived by the different methods.

3. A kit or device as claimed in claim 2, wherein the deriving means is arranged to derive the central thicknesses of lenses.

4. A kit or device as claimed in claim 2 or claim 3, wherein the deriving means is arranged to derive or enable a user to derive the thicknesses of lenses of at least one predetermined size by methods that correspond to the production of a lens at least by a method that comprises forming a lens blank of a standard size with a predetermined optical power and then shaping it to the said predetermined size, and by a method that comprises forming substantially the thinnest practical lens of the said predetermined size with the said predetermined optical power.

5. A kit or device as claimed in any one of claims 1 to 4, wherein the means for providing a display comprises a plurality of visible elements each having a width corresponding to a possible lens thickness.

6. A kit or device as claimed in any one of claims 2 to 4, or in claim 5 when dependent upon any one of claims 2 to 4, wherein the displayproviding means is arranged to display simultaneously and in juxtaposition corresponding thicknesses for equivalent lens of forms derived by at least two different methods.

7. A kit or device as claimed in claim 5, wherein the visible elements are of progressively differing widths and are arranged in order of thickness.

8. A kit or device as claimed in claim 5 or claim 7, or in claim 6 when dependent upon claim 5, wherein the visible elements are threedimensional objects.

9. A kit or device as claimed in claim 8, wherein the visible elements are plates of a size comparable with the sizes of the lenses the thicknesses of which are to be assessed and the said widths are the thicknesses of the plates.

10. A kit or device as claimed in claim 9, wherein the shapes of the plates projected into planes perpendicular to their said thicknesses are the same as those of the lenses the thicknesses of which are to be assessed.

11. A kit or device as claimed in claim 9 or claim 10, wherein the plates are flat.

12. A kit or device as claimed in anyone of claims 9 to 11, wherein the plates are secured together parallel to one another, spaced apart from one another in the direction of their thicknesses, and generally co-extensive in directions perpendicular thereto.

1 3. A kit or device as claimed in any one of claims 1 to 12, wherein the means for deriving the thickness comprises at least one numerical table.

14. A kit or device as claimed in claim 13, which comprises a plurality of tables each with at least two independent variables, and wherein there are respective tables for each of a plurality of values of at least one other variable.

1 5. A kit or device as claimed in claim 13 or claim 14, which comprises a stand or housing for the means for providing a display and wherein at least one said table is applied to an external surface of the stand or housing.

1 6. A kit or device as claimed in claim 15 when dependent upon claim 14, wherein a plurality of the said tables are applied to an external surface or external surfaces of the stand or housing.

1 7. A kit or device as claimed in claim 16, wherein an upstanding portion of the stand or housing is generally polygonal in plan view and has different tables applied to different sides.

18. A kit or device as claimed in claim 17, the said upstanding portion of which is a cuboidal lower portion of the stand or housing.

19. A kit or device as claimed in claim 17 or claim 1 8 when dependent upon claim 12, wherein the plates are arranged in a horizontal row extending over the said polygonal portion of the stand.

20. A kit or device as claimed in any of claims 1 to 19, wherein the means for providing a display is arranged to display thicknesses appropriate to spectacle-lenses and the deriving means is arranged to derive thicknesses from data appropriate to spectacle-lenses.

21. A kit or device as claimed in claim 20, wherein the deriving means is arranged to derive thicknesses for convex lenses.

22. A kit or device as claimed in claim 21, wherein the deriving means uses the data set out in the table shown in Figs. 6 to 10 of the accompanying drawings.

23. A kit or device for assessing thicknesses of lenses, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

24. Means for providing a direct visual and/or tangible display of the thickness of a selected part of a lens, suitable for use as the said means for providing a display in a kit or device as claimed in any one of claims 1 to 23.

25. Means as claimed in claim 24 for providing the display in a kit or device as claimed in any one of claims 5 to 12, 15 to 20, and 23.

26. A set of parts for a kit or device as changed in any one of claims 1 to 23 or for displayproviding means as claimed in claim 24 or claim 25.

27. An instrument for discriminating central thicknesses of lenses comprising: a plurality of plates each having a different thickness; and a supporting member for supporting said plurality of plates; by means of which before the edge of a lens has been processed a central thickness of the said lens after processing may be discriminated with actual feeling.

28. An instrument as claimed in claim 27, wherein the said plurality of plates comprise plates having the thicknesses equivalent to the respective central thicknesses of the lenses to be obtained by a plurality of methods of adjustmentprocessing the lenses.

29. An instrument as claimed in claim 27 or claim 28, wherein the said plurality of plates further comprise plates having thicknesses equivalent to the respective central thicknesses of lenses processed into a plurality of frame shapes of spectacles.

30. An instrument as claimed in any one of claims 27 to 29, wherein the said supporting member comprises a numerial value table representing the central thicknesses of the lenses after adjustment-processing as a function of at least the materials and optical powers of the lenses.

31. An instrument as claimed in claim 30, wherein the said numerical value table indicates the central thicknesses of the lenses after adjustment-processing as a function of the shapes and dimensions of the spectacle-frames that they are to fit.

32. An instrument as claimed in claim 30 or claim 31, wherein the said numerical value table further indicates the respective central thicknesses of the lenses to be obtained by a plurality of methods of adjustment-processing the lenses.

33. An instrument as claimed in any one of claims 27 to 32 wherein the supporting member comprises a holding axis or rod on which the said plurality of plates are arranged and four side wails, and wherein at least one of the said four side walls is formed integrally with the holding axis.

34. An instrument as claimed in claim 33, when dependent upon any one of claims 30 to 32, wherein one of the said four side walls comprises the said numerical value table.