CN1268240A - Apparatus for protecting and/or repairing an optical surface - Google Patents

Abstract

The present invention relates to a device for protecting and/or repairing damage to optical surfaces, the device comprising a thin-film member having a protective film (1) provided with an optical coupling medium (2) that is adapted to adhere to the surface with a resilient fit and adhesiveness.

Description

Devices for protecting and/or repairing optical surfaces

The present invention relates to devices for protecting and/or repairing surface damage to optical components, and more particularly to such devices in the form of composite thin film components.

Many optical devices contain surfaces whose uniformity depends on the corrective function of the device. For example, camera lenses, precision mirrors, optical storage devices, etc., if the optical surfaces of these devices are damaged, such as scratched, then the corrective function of the device can be adversely affected.

Taking optical storage devices (OSDs) as an example, these devices generally include disc-shaped transparent substrates on which optically recorded data are carried, and it is desirable to optically interrogate these devices in order to recover the data recorded on these substrates. Examples of such devices are (non-limiting) optical recording discs such as compact discs (CD).

OSDs such as CDs are generally durable, but are sensitive to minor scratches and other surface damage that easily exceed in size the typical size of the recorded data strings. Of course, there are some fairly sophisticated error recovery routines that can be built into electronic systems that wish to play back and/or reproduce most units of recorded data from such devices, but such systems have limited capabilities and they can be overwhelmed by damage. Frustrated, damage is extensive and/or of a certain type. For example, on a CD, damage from arcuate walking along the recorded track is usually much more severe than similar extensive damage from radial walking across the track. Therefore, there is a need to provide a film-shaped member that can be applied to a new OSD to protect its surface from damage, and/or if applied to the surface of an OSD that has already been damaged, it can at least reduce the risk of such damage. Adverse effects, as this impairment affects data integrity when played back from the OSD via optical interrogation.

My British patent GB-B-2279799 describes and claims a film-shaped member in which a fluid medium is provided between a protective plastic film and the interrogated surface of the OSC, the arrangement being such that the plastic film has a surface close to the OSD substrate The refractive index, or at least the portion of the substrate, through which it is desired to retrieve optically recorded data by means of interrogation, for example by laser readout. The fluid medium has a similar refractive index, and acts as an effective optical coupler, which flows into the surface topography of the OSD's substrate, thus filling scratches and other defects in the surface. The cohesive forces present in the fluid medium allow diffusion into the film between the plastic film and the OSD whereby, as a result of surface tension, the OSD prevents the plastic film from separating from the OSD in a direction perpendicular to the surface of the plastic film. If desired, another layer of film can be applied to the opposite side of the OSD, and if an edge locking mechanism is used, the two films can be conveniently locked in place at their edges by a common mechanism. However, since the fluid medium acts as an optical coupler between the plastic film and the OSD, such a coupler tends to go to the periphery of the disc under centripetal/centrifugal forces during use, eventually spreading away from the edge of the disc or at least in the Variable effects are produced over the surface area of the OSD. Obviously this is not desired.

My International Patent Application WO 96/21928 describes a system for providing an OSD housing, with a similar purpose to the above UK patent, however, here the fluid optical coupler can be replaced by a malleable solid material capable of spreading into surface defects . The housing is composed of properly arranged cooperating and mating parts, since other means of holding the OSD together with the film-shaped member may not be sufficient, namely being pushed by the high shear forces that would occur during the use of the OSD, the solid ductility The cohesive and electrostatic "snap-to-film" type forces within the coupler do not provide sufficient resistance to lateral sliding and separation between the film-shaped member and the OSD, thus requiring an enclosure. To generate such high shear forces, for example on a CD, it is rotated in use at high speeds relative to the readout conditions defined by the laser beam falling on the disc. However, using the entire housing to protect the OSD presents disadvantages, lack of space being an issue, and/or manufacturing cost issues.

The object of the present invention is to overcome the disadvantages of the above arrangements.

According to one aspect of the present invention, there is provided a device for protecting and/or repairing damage to an optical surface, said device comprising a film-shaped member having a resiliently bonded and adhesive device adapted to be adhesively retained on said surface. protective film for optical coupling media.

In this regard, it should be understood that it is the inherent viscosity of the coupling medium that causes the bond to remain on the optical surface.

The adhesive viscosity of the coupling medium significantly enhances the resistance to shear forces that would cause the film-shaped member to slide laterally relative to the device surface. So far, for reasons to be discussed below, it has been considered that the desired properties of the film-form member, especially with regard to the optimization of its refractive index and the requirements for the conformability of the optical coupling medium, are of great importance for the use of film-form member adhesives. Sticky hold has a big impact on the OSD. The invention allows this advantageous arrangement to be realized.

In this regard, the viscosity of the optical coupling medium is preferably sufficient to resist separation of the coupling medium, thereby resisting separation of the film-shaped member from the optical surface under normal operating conditions, while allowing manual removal of the film from the surface if necessary or desired shape components. When removing the film-form member from the optical surface, the optical coupling medium is preferably removed cleanly without leaving residues, so that a new film-form member can be applied without cleaning the optical surface.

The viscosity of the coupling medium is further preferably sufficient to overcome the internal resilience of the coupling medium, which will pull the coupling medium from any surface imperfections in the optical surface.

The optical surface can be provided as part of an optical storage device (OSD). In this case, the optical coupling medium is therefore preferably sufficiently viscous to avoid lateral sliding of the film-shaped member from the OSD during normal use of the OSD, while allowing manual removal of the film-shaped member.

Typically, although not necessarily, the surface will be one through or from which the information carried by the device can be derived by optical interrogation. Therefore, the film-shaped member is preferably formed of an optical gray scale material such as polycarbonate. However, any other suitable material may be used, including optical grayscale cellulose films.

According to another aspect of the present invention there is provided a method of protecting and/or modifying damage to the surface of an optical member, said method comprising the steps of:

(a) providing a protective film;

(b) providing a protective film having an optical coupling medium comprising a resiliently conformable and adhesive material to form the film-shaped member; and

(c) Adhesively fixing a film-shaped member to said surface through said optical coupling medium.

The optical coupling medium and protective film may be separate elements, and the optical coupling medium is applied to the film by a reverse gravure coating process to form the film-shaped member. On the other hand, the optical coupling medium can be formed integrally with the film by curing the two surfaces of the material from which the film-shaped member is made to different degrees, thereby providing an adhesive surface and a non-adhesive surface.

The invention also includes a device provided in sheet form according to the above, an OSD produced by the method described above, and/or incorporating a device as described above into the first aspect of the invention. The invention further includes optical coupling media for use with such an apparatus or such a method.

In order to understand the present invention more clearly and to facilitate the implementation of the present invention, specific embodiments will be described below by way of example only and with reference to the accompanying drawings, wherein:

FIG. 1 shows a plan view of an example of a film-shaped member according to the present invention, on which an easily peelable protective portion is attached.

FIG. 2 shows a cross-sectional view (not to scale) of a film-shaped member with a protective portion as shown in FIG. 1 .

Before referring to the drawings in detail, a general description of the invention is given.

Therefore, for simplicity and to avoid undue repetition, the present invention makes reference to CDs. However, as already described above, the present invention can be applied to any member having a surface, the optical properties of which have an important function, such as data scanners, lenses, mirrors, copiers and the like. Those skilled in the art will appreciate that refinements of detail are required to produce film-shaped members suitable for these other applications.

For application to CDs, then, the present invention provides a flat toroidal film-shaped member (comprising a protective film with optical properties similar to those of the CD itself and the resilient conformal viscous optical coupling medium) for at least the protection of the OSD Designed with the expectation that the surface will be interrogated or "read out" by a laser beam. The present invention also advantageously provides the auxiliary function of repairing small damage to the surface described above, allowing the resilient conformal viscous optical coupling medium to extend into scratches and the like.

The advantage of having an optical coupling medium is that the intensity of the laser beam drops by at least 5% as it passes over any surface, the "loss" of light intensity being caused by the light being spread out horizontally along the surface. Where a CD or other optical surface without an optical coupling medium is provided with a protective element, the light intensity will drop by at least 15% on each path through the protective element and the optical surface (there are three active surfaces through which light passes). Thus, when reading a CD, the intensity of the laser beam of the CD player will be reduced by at least 30% on the path between the laser beam of the CD player and the pickup device. This does not take into account other light intensity attenuation effects. However, in CD technology, when light passes through the disc substrate, the light intensity is further reduced due to absorption. Indeed, a further percentage of light is lost directly through the CD silver oxide coating, and such coatings are progressively thinned to reduce manufacturing costs. The term "reflectance" is used in the prior art as a measure of the percent decrease in the intensity of light falling on a CD. As an example, a CD without a protective cover has a maximum reflectivity of approximately 90% (5% reduction in light intensity entering the CD and 5% reduction upon exiting the CD).

The minimum acceptable reflectance for proper CD operation is believed to be about 70%, it should be understood that there is no optical coupling medium between the film-shaped protective member and the surfaces of the CD to reduce dispersion of light along these surfaces, the same exists in light extraction. The problem.

The optical coupling medium of the film-shaped member is fixed by its adhesiveness to both the protective film and the protected surface of the CD, having sufficient strength to resist forces acting during CD handling and playback that would pull the film-shaped member away from the CD . Specifically, not only peel forces acting in a direction substantially perpendicular to the protected surface, but also shear forces acting in the plane of the protected surface are blocked without further clamping or encapsulation of the device.

However, the viscosity of the optical coupling medium allows the film-shaped member to be removed, and the optical coupling medium can be stripped from the CD if replacement is required. Preferably, the film-shaped member can be peeled off the CD manually without damaging the CD and without leaving any residue of the optical coupling medium on the CD, so a new film-shaped member can be applied to the CD without Do cleaning work.

The refractive index of the optical coupling medium can be reasonably closely matched (at least within 20%, preferably within 10%, ideally within 5%) of the refractive index of the CD's transparent substrate, and when retrieved on the disc data, an interrogating laser beam passes through the disc substrate. CDs typically employ polycarbonate substrates with a refractive index of about 1.5, and suitable candidates for optical coupling media in these cases are silicone-based compounds. Furthermore, for CD applications, the optical coupling medium should have a birefringence of less than 100 nm.

However, there are significant obstacles to the use of this compound for this purpose. Recall that the optical coupling medium is ideally able to fill scratches etc. so that it adheres to the surface and repairs its small damages, providing the critical adhesive retention of the protective film to the surface being protected, and it is immediately noted that previously known silicone Compounds generally do not exhibit adhesive properties, instead they are commonly used as mold release agents and perform other anti-stick functions.

However, the present inventors have devised the following procedure which does enable the use of silicone-based compounds with the object of the present invention.

First, the catalyst is used in such a way as to prevent the overall curing of the silicone compound. Under partially cured conditions, the compounds exhibit resiliency and adhesion to the substrate and film materials used herein.

In one example, the silicone-based product DC781 (Dow Corning), which is a clear acetoxysilane-containing elastomer, was mixed with a higher viscosity level of 20% silicone fluid and cured at room temperature for about 1 hour. This prevents the DC781 product from fully curing so it remains adhesive and resilient. However, to speed up the partial cure time to the order of seconds, which is an advantage of commercial products, one can dilute the silicone product with a lot of solvent, and this is not a preferred process, mainly for environmental reasons.

In a more preferred embodiment, for example for an optical storage device in the form of a CD, the optical coupling medium comprises:

a) A large proportion (consisting of the maximum by weight) of the following materials:

1) Silicon dielectric gel (refractive index 1.4074), transparent low-viscosity silicone capsules. The gel is designed to create shock-absorbing, self-closing, resilient qualities; or

2) Silicone elastomers based on glycidoxy and trimethoxysilane organo groups (glycidoxypropyltrimethoxysilane, refractive index 1.428). This is a fast-curing silicone elastomer that is placed into a conformal coating; or

3) a silicone polymer mixed in a hydrocarbon solvent (refractive index about 1.5); and

b) A small proportion of silicone fluid, which is a clear colorless liquid, almost odorless, preferably with a viscosity between 0 and 2000η. The refractive index of this fluid is about 1.5, which is related to viscosity. Using a small proportion of silicone fluid increases the overall adhesion of the optical coupling medium. Reduction of catalyst elements (see below) will result in improved contact bonding quality.

A more specific composition included 15 parts by weight ("pbw") of Silcolease 426 (Rhone Poulenc Chemicals), two fast-acting catalysts, Catalyst 62a and Catalyst 62b (Rhone Poulenc Chemicals), 0.75 pbw each, 40 pbw of Toluene (a common commercial solvent), and 5 pbw of silicone oil Flll-10000 (with a high viscosity rating, supplied by Ambersil Ltd.). This mixture produces an optical coupling medium with the correct refractive index (1.55) for polycarbonate-based OSDs, which exhibits the other important properties discussed above.

Additional specific components are:

(A) 40 pbw of Sylgard 527A and B silicone dielectric gel (Dow Corning), 10 pbw of silicone oil (Dow Corning), and 20 pbw of toluene. This composition exhibits a refractive index of about 1.4.

(B) 40 pbw of DC781, 10 pbw of silicone oil and 30 pbw of toluene.

Both DC 781 and Sylgard 527 are based on silicone elastomers, the use of elastomers in the optical coupling medium allows the coupling medium to conform well to the surface topography of the OSD to be repaired/protected. It will be noted that the coupling medium is resilient/elastic so it is able to extend into the scratches rather than flow and creep into them. Therefore, the viscosity of the coupling medium should preferably be strong enough to resist the natural tendency of the coupling medium material to pull out of the scratch.

A further composition includes a Rhone Poulenc product called Poly200. This is a UV curable epoxy silicone. UV curing has the advantage that it does not require heat for curing, thus avoiding possible damage to the protective film and especially increasing its brittleness. In addition, UV curing can make the production process cheaper and faster, does not involve solvents, and is therefore environmentally friendly. The normal composition of this product is 100 parts polymer to 2.5 parts catalyst. The optical coupling medium was formed by reducing the catalyst by about 10% and adding 1 part silicone fluid.

Although the above advocates the use of silicone-based materials as optical coupling media, the present invention is not entirely contemplated for such use, e.g. contact adhesives could be used instead as long as their refractive index is suitable and in the surface area above is consistent.

In another embodiment, the film-shaped member may be integrally formed with the optical coupling medium. In this regard, the device can take the form of an optical film having the correct refractive index for the surface to be attached and having a birefringence level of less than 100 nm. Films can be produced using liquid compounds of the described properties, partially cured on one side and fully cured on the other side. This will result in a film with a tacky optical coupling medium surface on one side, and the other side is cured to be non-tacky, providing the necessary protective elements. A UV sensitive catalyst can be used for this purpose, where exposing one side of the film to UV light will cause that side to fully cure while the other side will remain semi-cured and tacky.

Description will now be made with specific reference to the accompanying drawings.

Conveniently, by means of a reverse gravure cylinder, the optical coupling medium is produced at 6 grams per square meter with a thickness of 6 microns, providing a protective film with the optical coupling medium 2, typically a polycarbonate film 1 of thickness 125 microns ( for CD protection). Of course, such dimensions can be varied to suit the application in which it is desired to produce a film-shaped member. In particular, the weight of the coupling medium may differ from the weight quoted above, it being noted that generally the heavier the weight, the easier it is for the optical coupling medium to adhere to the surface to be protected. It is preferable to carry out the process of applying the coupling medium in a clean room to reduce the risk of impurities or other undesirable inclusions in the optical coupling medium, which must be as smooth as possible once cured.

For transport and storage, the film-shaped member can be conveniently incorporated in a "sandwich" structure between inexpensive protective films with release agents. To this end, throughout the production process, the arrangement is as follows:

A 100 micron thick film 3 of polyester or similar inexpensive material is coated with a thin (eg 2 micron) and very low viscosity level contact adhesive. This material is then laminated with adhesive to a transparent polycarbonate film 1 (smooth on both sides), constituting the protective film element of the filmic structure 1, 2, thus having a thickness of 125 micrometers as previously described. A protective mask is provided starting on one or both sides of the smooth surface of the polycarbonate film; if provided, the mask is removed on one side to allow the application of the polyester film 3 so that it constitutes the carrier tape.

The mask (if provided) on the other smooth surface of the polyelastate film 1 is then removed and an optical coupling medium 2 of thickness 6 micrometers is applied on it, as described above preferably in a clean room, so , forming an adhesive and bonded optical coupling medium of the film-shaped members 1, 2. A protective release liner 4 is then applied to the media to maintain its finish and integrity with a thickness of approximately 36 microns. It should be understood that the release liner can be any convenient material that does not react with silicone and can be made smooth enough that the optical coupling medium does not begin to adhere to it. However, release liners are usually polyester.

The "sandwich material" thus constituted is then annularly cut, producing media of the appropriate shape and size for use in CDs. To this end, the release liner 4, the optical coupling medium 2 and the polycarbonate film 1 were cut from the above materials with a blade, resulting in an inner diameter of 42 mm and an outer diameter of 120 mm. A release tab 5 is formed on the outer edge of the release liner 4 to facilitate its removal by the end user.

The polyester carrier tape 3 is cut from below to an inner diameter of 15 mm and the same outer diameter of 120 mm +/- as for the other elements. Carrying out such cuts precisely, in the same center as the annular cuts made through the elements 1, 2 and 4, forms a pair of peel-off tabs 6, 7 on the outer edge of the carrier tape 3, on diametrically opposite sides of each other, to aid in the final User removal.

The end user applies the film-shaped member to the CD in the following manner.

The OSD should be clean, then place the recorded side (blank and bright) into a normal CD storage case (often called a "jewel" case). The release liner 4 is then removed from the optical coupling medium 2 of the film-shaped member 1, 2, by utilizing the release tab 5 on the release film 4 and the two release tabs 6, 7 on the polyester carrier tape 3, avoiding In contact with the surface of the optical coupling medium. The film-shaped members 1, 2 are then placed with the optical coupling medium side down on the CD, through their 15 mm co-operation, the film-shaped members are centered by means of the central pivot in the jewel box, centered in the carrier tape 3 cut hole. Once the film-shaped member is properly in place on the CD, the polyester carrier tape 3 is removed, again using the peel tabs 6,7 formed thereon, and the film-shaped member 1,2 is checked for proper seating. Squeeze out any visible air bubbles between the film-shaped member and the CD by applying light radial downward pressure with the thumb. If necessary, the top surface of the protective element 1 of the film-shaped member can be cleaned and the CD is then ready to be played.

It should be understood that the illustrated embodiments are indicative of the invention in some form for use as described. In fact, the present invention can be applied in many different structures, and the detailed embodiments are directly left to those skilled in the art. For example, the dimensions of the various components may be changed as desired. Furthermore, while the film-shaped member is preferably formed from a plastic material such as polycarbonate, any suitable alternative material may be used.

Claims (20)

1. a protection and/or repair device to the optical surface damage is characterized in that described device comprises film shape member, has to be provided with to be suitable for the bonding protective film that remains on the optical coupled medium of described lip-deep resilience applying and viscosity.

2. device as claimed in claim 1 is characterized in that: described protective film is a plastic material.

3. device as claimed in claim 1 or 2 is characterized in that: described optical coupled medium is a silicone based material.

4. device as claimed in claim 3 is characterized in that: described optical coupled medium comprises catalyzer, and its quantity allows silicone partly solidified.

5. as one of above-mentioned claim described device, it is characterized in that: in described protective film and described optical coupled medium, comprise the protective film that is easy to open at least one.

6. as the described device of one of above-mentioned claim, it is characterized in that: described surface is will be by it or from the surface of its derived information by optical challenge.

7. as one of above-mentioned claim described device, it is characterized in that: provide with sheet form.

8. as one of above-mentioned claim described device, it is characterized in that: the optical coupled medium is to be suitable for a bonding individual course that remains on the protective film.

9. as one of above-mentioned claim described device, it is characterized in that: the refractive index of protective film and/or optical coupled medium is similar to the refractive index of optical surface.

10. as one of above-mentioned claim described device, it is characterized in that: the optical coupled medium comprises that the permission resilience fits to the elastic body on the optical surface.

11. as one of above-mentioned claim described device, it is characterized in that: optical surface is optical memory device (OSD), and the viscosity of optical coupled medium is such:

1) stop film shape member to separate in normal working conditions with OSD;

2) allow to go up the manual film shape member of removing from OSD;

3) be enough to overcome the inside screen resilience of optical coupled medium, it will draw back the optical coupled medium from any surface imperfection of optical surface.

12. a protection and/revise method to the optical component surface damage, it is characterized in that described method comprises step:

(a) provide protective film;

(b) provide the protective film that has the optical coupled medium, to form a film shape member, described optical coupled medium comprises the material of resilience applying and viscosity.

(c) by described optical coupled medium film shape member is adhesively secured on the described surface.

13. method as claimed in claim 12 is characterized in that: described optical coupled medium is to be applied on the described film by reverse intaglio printing coating process.

14. as claim 12 or 13 described methods, it is characterized in that: the optical coupled medium is a silicone based material.

15. as the described method of one of claim 12 to 14, it is characterized in that: the optical coupled medium is by described silicone based material is formed by quantitatively mixing mutually with catalyzer, to allow it partly solidified, allow the optical coupled medium to be adhered on the optical surface at least thus.

16. as the described method of one of claim 12 to 15, it is characterized in that: the film that will be convenient to open during storage and transmission is applied on the film of being protected and/or optical coupled medium.

17. an optical storage is characterized in that: described device be loaded with according in the claim 1 to 11 any one device and/or by the film shape member that produces according to the method for any one in the claim 12 to 16.

18. the optical coupled medium of resilience applying and viscosity is characterized in that: described optical coupled medium in the claim 1 to 11 any one device and/or claim 12 to 17 in any one method use.

19. protect and/or repair device, it is characterized in that basically with reference to the accompanying drawings as previously mentioned for one kind to the optical surface damage.

20. protect and/or repair method, it is characterized in that basically with reference to the accompanying drawings as previously mentioned for one kind to the optical surface damage.

Images