AU627087B2

AU627087B2 - Lens polishing apparatus

Info

Publication number: AU627087B2
Application number: AU65945/90A
Authority: AU
Inventors: Steve Newman
Original assignee: ALOREN NO 59 Pty Ltd
Current assignee: Aloren (no59) Pty Ltd
Priority date: 1989-11-08
Filing date: 1990-11-08
Publication date: 1992-08-13
Anticipated expiration: 2010-11-08
Also published as: AU6594590A

Description

iOr if ~i li i Our Ref: 295610 8270S7

AUSTRALIA

Patents Act FORM COMPLETE SPECIFICATION

(ORIGINAL)

Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: a 0 Applicant(s): Address for Service: Aloren (No.59) Pty Ltd 191 Flinders Street ADELAIDE SA 5001

AUSTRALIA

ARTHUR S. CAVE CO.

Patent Trade Mark Attorneys Level 10, 10 Barrack Street SYDNEY NSW 2000 Complete specification for the invention entitled i "Lens polishing apparatus invention, including the The following statement is a best method of performing it full description of this known to me:- 0 I 0 ^8316 081190 't- 1 5020 0106j i 4 LENS POLISHING SYSTEM AND APPARATUS THEREFOR The present invention relates to an improved lens polishing technique and associated apparatus therefor.

One of the steps in the procedure for preparation of lenses such as contact lenses, involve polishing cf the lens following machining. Among the prior art methods of polishing lenses (especially base curves or back surfaces) includes the formation of a crrved contour in a polishing machine onto which the lens is placed for polishing. The curved contour is f'ormed with a hard and unyielding surface. This formed curved surface is then covered by the polishing cloth or polish carrier and then presented to the lens in a spinning or rocking action. The lap/cloth/polishing medium is formed cz,-h that it must 15 approximate the curve it is going to polish very closely.

If this does not occur, the result will be unpolished surface areas, poor surface quality on and poor optics in the lens. If the curve does not conform to the curve of the .0o lens it will also polish only one surface at a time or just over one surface at a time. Prior art methods such as the 0. aforesaid method suffer from inherent disadvantages. One of the major disadvantages results from the unyielding nature of the material which has been and is presently used for .0 supporting the lens. If the material which is used is unyielding, then by necessity the curvature in the lap must be accurately formed and maintained on a regular basis so 4 that there would be accurate conformity between the lens curvature and the lap curvature during polishing. It also i follows that the curve to be polished must similarly be maintained in the above manner.

8 1 \The reason the prior art laps are unyielding in nature stems from the fact that they are generally made from metal, I plastic, resin and other like substances. According to one .4 embodiment of the prior art methodology the covering is usually applied over the lap in a generally even manner to facilitate the smoothness and evenness of surface quality, to prevent scratching or scouring of the lens and to hold the polish in close contact with the polishing surface.

As an alternative to this, some practitioners of the :4 .sA l-^h c 1.

0106j -2art prefer not to use this covering system but machine their laps to extremely close tolerances and utilise the properties of the lap to polish the surface of the lens.

Thus, a major disadvantage of the prior art methods resides in the generally unyielding nature of the materials used for polishing laps and also due to their surface properties. Also, mismatching of the curvature of the lap and the lens results in introduction of dust or other impurities or foreign bodies to the polishing surface thereby resulting in poor surface quality and scratching.

A further disadvantage is that generally only one curve can be polished at one time thereby slowing the polishing step in lens manufacture. The present invention seeks to overcome the aforesaid B' 15 disadvantages by providing a polishing technique consisting *of a lap (or mandrel/s or chuck/s) detachably or fixedly attached to which is a soft compound formed into a hemisphere of spherical or aspheric or sphero aspheric or sphero-flatshape.

This soft formed shape is moulded, lathed or formed in.

0 another manner such that the contact lens curve or spectacle 4 0° element or optical element curve is polished via a constant, intimate contact over all or part of the surface to be 0polished. Due to the softness of the compound, the lap will 25 mould itself to the curve or curves or'asphericity or flat/s of the lens or base being polished. The result of providing a lap with a compound having different surface properties and mechanical properties from the prior art is that a close moulding action will ensure that an all over even polishing action that pre empts any need for multi lap polishing will be achieved.

Furthermore, the interface between the lap and the article being polished need not be manufactured to close tolerances as the lap will absorb any of these discrepancies when it readily conforms to the contour of the lens being polished.

The moulding action of this system will polish all manner of spherical, multi spherical, sphero-aspheric, i sphere flat, multi sphere aspheric, multi sphere flap, S'.^i 0106j -3 toric, toric-sphere combinations, toric aspheric combinations in one operation and will ensure good surface finish, blending, and a trueness of curvature.

Another advantage of this polishing system over conventional methods of polishing lenses is the ability to repolish surfaces with minimal changes to the curvature or shape factor. With conventional techniques, repolishing usually cannot be achieved without altering or reshaping the curvature or radii. It has been shown that with this polishing techniqud'even complex lens forms can be polished and repolished with little or no deterioration to che lens/surface shape factor.

In one broad form the'-present invention comprises an improved polishing technique for lenses particularly contact Ce., 15 lenses, utilising an apparatus comprising a mandrel over which or in association with, is placed a material of soft compound formed substantially into a hemisphere of spherical Cor aspheric or sphero aspheric or sphero flat shape, wherein when a lens is to be polished, the lens is brought into 20 apposition with or in close proximity to the surface of the S0 soft compound to facilitate polishing of the lens over the I 0 full surface of the area of the lens to be polished.

In its broadest form the present invention comprises a C contact lens cleaning and polishing apparatus adapted for 25 use with a lens polishing machine,, the apparatus comprising; a mandrel over which is placed a soft compound T resiliently flexible membrane for supporting a lens and which conforms the contour of the lens surface when the lens is placed thereon for polishing, wherein when a lens is to be cleaned or polished the j, lens is brought into apposition with or in close proximity to the surface of the soft compound membrane to facilitate even polishing and/or cleaning over the full surface of the area of the lens.

According to the method aspect,, the present invention comprises a method for evenly polishing and/or cleaning a lens using the apparatus as hereinbefore described I comprising the steps of: placing the apparatus on a polishing machine support; 0106j -4 044 0 alSo 0 o 00 00 *0 0 0 00 0

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0000.0 pressurising a fluid inside the apparatus which causes the membrane which is affixed to the mandrel to assume a predetermined contour according to the degree of pressurisation; optionally sealing the surface of the membrane to render the membrane impervious to polishing solvents; placing the lens in a position so that motion imparted to the mandrel causes a surface of the lens to be evenly polished with the said membrane conforming to the contour of the lens surface. In the preferred embodiment, the soft material which makes up the soft lap can be any soft yet resilient material. Preferably the soft substance is made from rubber, PVC, urethane or like materials. In another 15 embodiment the soft material is sealed over its surface from contact with normal polishing or cleaning solvents.

Alternatively, the soft surface is not provided with a sealing surface thereby allowing contact with normal polishing or cleaning solvents.

20 Where the surface is sealed the preferred sealing method is via a resilient covering which is impervious to the rigours of constant polishing and solvents. Certain PVC materials, vinyls or rubber sheeting is suitable for the purpose of sealing the soft surface.

25 According to one embodiment the membrane is fixed to the mandrel by gluing to effect a total seal.

Alternatively, the membrane may be screwed to the mandrel with a sealing hoop sandwiching the membrane between the hoop and mandrel wall.

The invention will now be described in more detail and with reference to the accompanying drawings wherein: Fig 1: shows an apparatus for polishiLng the back surface of a lens according to one embodiment of the present invention.

Fig 2: shows an alternative embodiment of the apparatus of the present invention showing means for pressurising a fluid beneath the soft membrane on the apparatus.

Fig 3: shows an apparatus for polishing the front surface of a lens according to a preferred embodiment.

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0106j Fig 4: shows an apparatus for cleaning/polishing the front surface of a lens according to an alternative embodiment and showing means to enable creation of a vacuum/or fluid buffer beneath the surface of the membrane thereon.

Referring to figure 1 there is shown an apparatus for the purpose of effecting polishing of a back surface of a lens following manufacture of the lens. The apparatus 1 comprises a supporting mandrel 2 made preferably of metal rubber or wood and an upper portion 3 which comprises a soft membrane 4 having there beneath a fluid 5 to enable adjustment to be made to the contour of the membrane 4. The membrane may be attached to..the mandrel by gluing, screwing clamping or other suitable means to create a seal to prevent .9 ~fluid 5 escaping.

o, Figure 2 shows an apparatus 6 similar to the apparatus "1 shown in figure 1 however, this time the apparatus has its supporting mandrel 7 manufactured with valve means 8 to enable pressurisation of a fluid 9 which resides in a space 'o underneath the membrane 10. The membrane 10 can either be of uniform or non uniform thickness so as to enable different shapes to be presented to a surface to be polished according to requirements.

o The supporting mandrels 2 and 7 of both figures 1 and 2 r .respectively can be fabricated from any conventional material with their primary purpose to hold, support and anchor the membrane 4 and 10 respectively and the fluid and 9 respectively. Each mandrel is adapted with a tapered portion 11 as shown in figure 2 in order to provide a means for location that is, axial alignment of the lens where 30 required.

The mandrels are adapted via the tapered portions to i locate on a conventional polishing apparatus which provides the appropriate motion for the polishing activity. The mandrel with the adjustable and readily deformable membrane greatly improves the polishing quality on a lens.

The mandrel may be detachably fixed to a support via the taper on a conventional polishing machine (not shown).

The lens is supported above the membrane by a suitable

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cNT 0 kii ~t o4 0106j -6 support according to conventional means.

Figure 3 shows an apparatus 12 for the purpose of cleaning/polishing a front surface of a lens (not shown).

The apparatus 12 comprises a supportingmandrel 13 and a softer material which is brought into apposition with or in close proximity to a lens to be polished. In this embodiment the membrane 14 is contoured with the assistance of a fluid medium 15 which lies underneath the membrane.

Figure 4 shows an alternative embodiment of an 0 apparatus 16 for the purpose of polishing the front surface of a lens. The apparatus 16 as with the previous embodiments described comprises a mandrel 17 and a membrane o 9 18 which can have uniform thickness or non uniform thickness so as,,to create different shapes. In an alternative 15 embodiment the membrane may be adapted with a sealing 15 a: coating if it is desired that the membrane material not come in contact with polishing apparel. The mandrel 16 has associated therewith valve means 19, which enables the creation of a vacuum in the space under the membrane 18 occupied by fluid 20 As with the embodiments shown in figure 2, the vacuum which can be created in figure 4 is created by conventional means such as by use of a standard valve and motor.

a a The soft resilient nature of the membranes used as 25 polishing laps eliminates any surface mismatching between 25 the lens surface and the lap and prevents the introduction of foreign impurities there between. It also polishes a number of curves or similar in one operation. The surface quality is greatly improved in comparison to the prior art methods used due to the constant intimate relationship between lap and polish surface.

The polishing apparatus can encompass some of the traditional polishing practices in the utilisation of covering cloth, silk, vinyl, etc. (not shown in the drawings) This does not detract from the system but enhances its flexibility in polishing all types of lens surface types.

It allows the operator to use this type of lap on all 1 A4 occasions rather than having specialised types of polishing

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I 0106j 7 systems. The polishing lap is manufactured via moulding, lathing or similar techniques. It is generally attached to a firm support which attaches to any standard polishing machine. The support can be made from metal, plastics or wood, etc. and can be fashioned in any shape or form to suit the particular machine.

Where the membrane surface is sealed, it is preferable that the sealing method is via a resilient covering which is impervious to the rigours of constant polishing solvents.

The fluids described in each of the embodiments shown in figures 1 to 4 of the drawings may be liquid or gas, such as water oil or air.

By applying varying types of pressure to the membranes, the lap can be inflated or swollen to the required size and selected contoured shape and elasticity. This results in a predetermined contour being presented to a surface to be polished.

The contour of the membrane which is achieved is dictated by the pressure applied to the fluid and the 20 inherent elasticity of the membrane. The radii of the curve St can be altered therefore by changes in fluid pressure o according to the characteristics of the lens to be cleaned.

In a preferred embodiment of the polishing apparatus it S"a will be appreciated that various combinations of the above described features both in the drawings and the description '25 can be achieved according to requirements. This provides flexibility in the design of each mandrel and membrane without departing from the intention behind the present invention, The flexibility provided by the pressurisation under the fluid of the membrane enables an operator to create a lap with a spongy surface via a thick membrane with a hard supporting surface underneath where required. This can be provided for both front and back surface polishing applications.

It will be recognised by persons skilled in the art that numerous variations and modifications can be made to the present invention without departing from the overall spirit and scope of the invention as broadly described herein.

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Claims

1. A contact lens cleaning and polishing apparatus adapted for use with a lens polishing machine the apparatus comprising; ~a mandrel over which is placed a soft compound- resiliently flexible membrane for supporting a lens and ~'which conforms the contour of the lens surface when the lens is placed thereon for polishing, wherein when a lens is to be cleaned or polished the lens is brought intc apposition with the surface of the soft a acompound membrane to facilitate even polishing and/or cleaning over the full surface of the area of the lens. a An apparatus accordin 'to claim 1 further comprising a a cavity' formed between the mandrel and membrane for holding a 5 fluid therein at a predetermined pressure which causes the soft compound membrane to assume a contour commensurate with a the degree of pressure exerted thereon by the fluid. a a3. An apparatus according to claim 2 wherein the said soft a a~ compound membrane is formed substantially into a hemisphere Of spherical, aspheric, sphero aspheric or sphero flat shape j according to the fluid pressure exerted thereon. aaa4.s An apparatus according to claim 3 wherein the mandrel alocomprises an adaptor to enable the pressurisation of the fluid introduced into the cavity to enable selective adjustment to -,he contour of the said soft membrane. An apparatus according to claim 4 wherein the membrane is made from rubber urethane or like materials.

6. An apparatus according to claim 5 wherein the surface 24 of the membrane is optionally sealed to provide a barrier between the membrane surface-and cleaning solvents placed thereon.

7. An apparatus according to claim 6 wherein the mandrel has a tapered recess to enable detachable or fixed mounting on a support on a polishing machine and to facilitate axial alignment between the lens axis and the longitudinal axis of the mandrel.

8. An apparatus according to claim 7 wherein the said recess tapers inwardly and upwardly from the base of the mandrel enabling tight interfitting between the mandrel and NTO.' 0106j -9- said support.

9. An apparatus according to claim 8 wherein the membrane is connected to said mandrel by means of gluing, screwing, clamping or other like means. An apparatus according to claim 9 wherein the fluid is gas, water or oil.

11. An apparatus according to claim 10 wherein the fluid is pressurised via a valve associated with an inlet passage in said mandrel.

12. An apparatus adcording to claim 11 wherein the contour of the membrane is dictated both by the inherent elasticity of the membrane and the degree of pressure exerted by the fluid upon pressurisation on the membrane.

13. A~n apparatus according to cla.L... 12 wherein the 000 15polishing of the lens takes place over all or part of the 0.,..surface of the lens to be polished. ci 14. An apparatus according to claim 13 wherein even polishing of the lens takes place ;C ia constant intimate contact between membrane and lens by conformity of the 20membrane with the contour of the service of a lens being polished. An apparatus according to claim 14 wherein the back and/or front surface of a lens is polished by conformity of the membrane contour to the front or back contour of the lens.

16. An apparatus according to claim 15, wherein the fluid is either homogenous or non homogenous.

17. A method of polishing a lens using the apparatus as hereinbefore described comprising the steps of; placing the apparatus on a polishing machine support; pressurising a fluid inside the apparatus which causes the membrane which is affixed to the mandrel to assume a predetermined contour according to the degree of pres surisation; optionally sealing the surface of the membrane to render the membrane impervious to polishing solvents; placing the lens in a rnosition so that motion imparted to the mandrel causes a surface of the lens to be evenly 'S A41 polished with the said membrane conforming to the contour of ~NT 0 0106j 10 the lens surface.

18. An apparatus as hereinbefore described and with reference to the accompanying illustrations.

19. A method as hereinbefore described and with reference to th accompanying illustrations. DATED this 12th day of May, 1992. ALOREN (NO. 59) PTY LTD ,o By Its Patent Attorneys DAVIES COLLISON CAVE 0 a o a 0 0 N o so a 0o 0 B s 6 a ea o F I .i 1, I