CA1241744A - Protective rim for storage discs - Google Patents
Protective rim for storage discsInfo
- Publication number
- CA1241744A CA1241744A CA000473768A CA473768A CA1241744A CA 1241744 A CA1241744 A CA 1241744A CA 000473768 A CA000473768 A CA 000473768A CA 473768 A CA473768 A CA 473768A CA 1241744 A CA1241744 A CA 1241744A
- Authority
- CA
- Canada
- Prior art keywords
- substrate
- storage disc
- annular
- disc
- recording layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000003860 storage Methods 0.000 title claims abstract description 69
- 230000001681 protective effect Effects 0.000 title claims abstract description 29
- 239000000758 substrate Substances 0.000 claims abstract description 86
- 230000005855 radiation Effects 0.000 claims abstract description 6
- 239000000463 material Substances 0.000 claims description 10
- 239000004033 plastic Substances 0.000 abstract description 7
- 229920003023 plastic Polymers 0.000 abstract description 7
- 230000008646 thermal stress Effects 0.000 abstract description 2
- 239000000853 adhesive Substances 0.000 description 13
- 230000001070 adhesive effect Effects 0.000 description 13
- 125000006850 spacer group Chemical group 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 6
- 230000004224 protection Effects 0.000 description 6
- 230000035882 stress Effects 0.000 description 6
- 230000035939 shock Effects 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 239000004411 aluminium Substances 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 239000011521 glass Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229920005549 butyl rubber Polymers 0.000 description 2
- 238000013016 damping Methods 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 239000000806 elastomer Substances 0.000 description 2
- 230000033001 locomotion Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000006748 scratching Methods 0.000 description 2
- 230000002393 scratching effect Effects 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000013536 elastomeric material Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000003334 potential effect Effects 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/24097—Structures for detection, control, recording operation or replay operation; Special shapes or structures for centering or eccentricity prevention; Arrangements for testing, inspecting or evaluating; Containers, cartridges or cassettes
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/24015—Air-sandwiched discs
Landscapes
- Optical Record Carriers And Manufacture Thereof (AREA)
- Packaging For Recording Disks (AREA)
Abstract
ABSTRACT:
A storage disc has a transparent substrate (21) on which a recording layer (22) has been deposited, which layer can be modified locally by means of a radiation beam and is covered with a cover disc, for example in the form of an identical second transparent substrate (23) which is spaced from the recording layer and secured to the first substrate by annular means (26, 27) so as to enclose a sealed space (24). Protective circumferential means (25) form part of the annular means (26) to protect the peripheries (29) and (214) of both substrates which are vulnerable to impact forces and thermal stresses. It is essential that spaces (212, 213) are formed between the substrate peripheries and the circumferential means in which no means are present which can transmit undesirably large forces in the case of deformation of the circumfer-ential means. Thus, all forces, or at least such a part of the forces that fracture of the substrates is prevented, are transmitted via the annular means to the flat sides of the substrates only. The circumferential means may be subjected locally to plastic deformation to absorb impact energy.
A storage disc has a transparent substrate (21) on which a recording layer (22) has been deposited, which layer can be modified locally by means of a radiation beam and is covered with a cover disc, for example in the form of an identical second transparent substrate (23) which is spaced from the recording layer and secured to the first substrate by annular means (26, 27) so as to enclose a sealed space (24). Protective circumferential means (25) form part of the annular means (26) to protect the peripheries (29) and (214) of both substrates which are vulnerable to impact forces and thermal stresses. It is essential that spaces (212, 213) are formed between the substrate peripheries and the circumferential means in which no means are present which can transmit undesirably large forces in the case of deformation of the circumfer-ential means. Thus, all forces, or at least such a part of the forces that fracture of the substrates is prevented, are transmitted via the annular means to the flat sides of the substrates only. The circumferential means may be subjected locally to plastic deformation to absorb impact energy.
Description
PHN. 10.943 The invention relates to an optically readable storage disc which comprises:
- a flat transparent substrate with flat sides and a cixcular periphery, - a recording layer which can be modified locally by means of a radiation beam and which is situated on a flat side of the substrate, - a cover disc which is secured to the substrate by annular means with interposed adhesive means such as a layer of adhesive, so as to be spaced from at least that part of the recording layer near the periphery and in such a manner that a sealed space is enclosed between the sub-strate and the cover disc, and - protective circumferential means which form part of the 1~ annular means and which have.a circumference with an outer diameter which is larger than that of the sub-strate.
Such a storage disc is disclosed in, for example, Japanese Patent Application JP-PA 57-74842 (Patents Ab-~tracts of Japan), Vol. 6, No. 156 (P-135)(1034), August 198~. The known storage disc comprises two flat disc members and annular means formed by concentric inner and outer annular spacers which are interposed between said ~isc m~mbers near a centre hole and near the outer circum-~5 exence respectively of the storage disc to.affix saiddisc members to each other by means of an adhesive. The outer.annular spacer comprises protective circumferential means in the form of a cylindrical mounting ring which extends transversely of the interposed portion and between which the two said flat disc members are mounted.
Optical storage discs have a very high informa-tion storage capacity. For example, a storage disc having a PHN. 10.943 2 diameter of 30 cm can store approximately one giga-bit of information on each recording side. Once the storage disc has been provided with information the value of the stor-age disc is no longer equal to the price of a blank storage disc but rather depends on the importance of the informa-tion stored on it. Loss of recorded information may have serious conse~uences.
In optical storage discs the substrate should be o a high optical quality. Moreover, the substrate should comply with some other requirements depending on the radiation-sensitive material used. Currently, substrates of hard glass (see U.S.-PS 4,074,282) or of a high-~uality plastics such as polymethylmetacrylate or poly-carbonate are often used. Both said hard-glass substrates and said plastics substrates are susceptible to damage by forces acting on the outer rim, in the plane of the sub-strate or impact forces. However, the storage disc is not unlikely to be subjected to such impact forces, for example if the storage disc inadvertently slips out of the hands o the user or if during handling the storage disc strikes against objects in its proximity. Moreover, allowance must be made for the fact that storage discs of the type discussed here are usually intended for filing ~urposes, which means that a service life of at least 10 ~5 y~ars is required. During this long period the storage disc may have to be handled many times.
Despite the pressure of the mounting ring the known storage disc is not protected ade~uately against damage by external forces impinging on, for example, the outer rim and caused by falling or shocks, not even if the storage disc is accommodated in a cassette. This is because the impact forces are transmitted directly to the disc members via the cylindrical mounting ring in which they are mounted.
~he likelihood of damage to the storage disc is not always minimized by accommodating the storage disc in P~N 1O943 3 ~ 23-Ol-85 a cassette. This is because the cassette itself has also a certain mass. If the cassette is readily deformable the impact load exerted on the rim of the stora~e disc may be even larger than in the absence of a cassette. However, the cassette does provide satisfactory protection against damage due to forces which ac~ perpendicularly to the plane of the storage disc.
Another disadvantage of the known storage disc is that it may happen that the substrate fractures when the storage disc is subjected to a thermal cycle This is be-cause at its circumference the glass substrate is mounted in the cylindrical mounting ring which will not expand to the ~ame e~tent as the substrate during said thermal cycle.
~or e~ample, if the mounting ring is made of a metal1 this may result in the periphery of the substrate being sub~
jected to substantial faces.
The invention aims at solving this problem of the known storage disc and to this end it is characterized in that between the circumference of the substrate and cir-cumferential means a space is formed which is substantial-ly free of intermediate means which in the case of de-formation of the periphery of the circumferential means can transmit to the periphery of the substrate a force which is directed to the centre of the substrate and which has such a magnitude that it can damage the substrate.
In many cases it will be preferred if the space between the periphery of the substrate and the circumferential means is completely void. In the case of deformation of the circumferential means this ensures that no forces at 30 nll c~n be e~erted on the periphery of the substrate.
However, it is also conceivable that said space is filled with a readily deformable material.
If the outer wall of the protective rim of the storage disc in accordance with the invention is subjected 35 to shocks these are not transmitted to the periphery of the substrate but, via the annular means, to a flat side of the substrate, namely by shear stresses in the adhesive ~2~L~L7~
PHN. 10.943 4 means between the substrate and the annular means. Adhe-sive means such as layers of adhesive, as is known, can withstand shear stresses comparatively well. Since the annular means are very rigid in the plane in which they are situated, the faces exerted on the substrate via the adhesive means will be distributed over the entire area or at least a part of the area covered by the adhesive means.
An embodiment of the invention is characterized in that said annular means and circumferential means to-gether constitute a flat ring having an outer diameter which is larger than that of the substrate. This embodi-ment has several advantages. The combination of annular means and protective circumferential means has the sim-plest shape, namely that of a flat ring. The mass of thesemeans is minimal, which ma~ be important in order to mini-mize the mass inertia and the mass eccentricity of a rapidly rotating storage disc. There are no portions which project from the flat side of the substrate which should
- a flat transparent substrate with flat sides and a cixcular periphery, - a recording layer which can be modified locally by means of a radiation beam and which is situated on a flat side of the substrate, - a cover disc which is secured to the substrate by annular means with interposed adhesive means such as a layer of adhesive, so as to be spaced from at least that part of the recording layer near the periphery and in such a manner that a sealed space is enclosed between the sub-strate and the cover disc, and - protective circumferential means which form part of the 1~ annular means and which have.a circumference with an outer diameter which is larger than that of the sub-strate.
Such a storage disc is disclosed in, for example, Japanese Patent Application JP-PA 57-74842 (Patents Ab-~tracts of Japan), Vol. 6, No. 156 (P-135)(1034), August 198~. The known storage disc comprises two flat disc members and annular means formed by concentric inner and outer annular spacers which are interposed between said ~isc m~mbers near a centre hole and near the outer circum-~5 exence respectively of the storage disc to.affix saiddisc members to each other by means of an adhesive. The outer.annular spacer comprises protective circumferential means in the form of a cylindrical mounting ring which extends transversely of the interposed portion and between which the two said flat disc members are mounted.
Optical storage discs have a very high informa-tion storage capacity. For example, a storage disc having a PHN. 10.943 2 diameter of 30 cm can store approximately one giga-bit of information on each recording side. Once the storage disc has been provided with information the value of the stor-age disc is no longer equal to the price of a blank storage disc but rather depends on the importance of the informa-tion stored on it. Loss of recorded information may have serious conse~uences.
In optical storage discs the substrate should be o a high optical quality. Moreover, the substrate should comply with some other requirements depending on the radiation-sensitive material used. Currently, substrates of hard glass (see U.S.-PS 4,074,282) or of a high-~uality plastics such as polymethylmetacrylate or poly-carbonate are often used. Both said hard-glass substrates and said plastics substrates are susceptible to damage by forces acting on the outer rim, in the plane of the sub-strate or impact forces. However, the storage disc is not unlikely to be subjected to such impact forces, for example if the storage disc inadvertently slips out of the hands o the user or if during handling the storage disc strikes against objects in its proximity. Moreover, allowance must be made for the fact that storage discs of the type discussed here are usually intended for filing ~urposes, which means that a service life of at least 10 ~5 y~ars is required. During this long period the storage disc may have to be handled many times.
Despite the pressure of the mounting ring the known storage disc is not protected ade~uately against damage by external forces impinging on, for example, the outer rim and caused by falling or shocks, not even if the storage disc is accommodated in a cassette. This is because the impact forces are transmitted directly to the disc members via the cylindrical mounting ring in which they are mounted.
~he likelihood of damage to the storage disc is not always minimized by accommodating the storage disc in P~N 1O943 3 ~ 23-Ol-85 a cassette. This is because the cassette itself has also a certain mass. If the cassette is readily deformable the impact load exerted on the rim of the stora~e disc may be even larger than in the absence of a cassette. However, the cassette does provide satisfactory protection against damage due to forces which ac~ perpendicularly to the plane of the storage disc.
Another disadvantage of the known storage disc is that it may happen that the substrate fractures when the storage disc is subjected to a thermal cycle This is be-cause at its circumference the glass substrate is mounted in the cylindrical mounting ring which will not expand to the ~ame e~tent as the substrate during said thermal cycle.
~or e~ample, if the mounting ring is made of a metal1 this may result in the periphery of the substrate being sub~
jected to substantial faces.
The invention aims at solving this problem of the known storage disc and to this end it is characterized in that between the circumference of the substrate and cir-cumferential means a space is formed which is substantial-ly free of intermediate means which in the case of de-formation of the periphery of the circumferential means can transmit to the periphery of the substrate a force which is directed to the centre of the substrate and which has such a magnitude that it can damage the substrate.
In many cases it will be preferred if the space between the periphery of the substrate and the circumferential means is completely void. In the case of deformation of the circumferential means this ensures that no forces at 30 nll c~n be e~erted on the periphery of the substrate.
However, it is also conceivable that said space is filled with a readily deformable material.
If the outer wall of the protective rim of the storage disc in accordance with the invention is subjected 35 to shocks these are not transmitted to the periphery of the substrate but, via the annular means, to a flat side of the substrate, namely by shear stresses in the adhesive ~2~L~L7~
PHN. 10.943 4 means between the substrate and the annular means. Adhe-sive means such as layers of adhesive, as is known, can withstand shear stresses comparatively well. Since the annular means are very rigid in the plane in which they are situated, the faces exerted on the substrate via the adhesive means will be distributed over the entire area or at least a part of the area covered by the adhesive means.
An embodiment of the invention is characterized in that said annular means and circumferential means to-gether constitute a flat ring having an outer diameter which is larger than that of the substrate. This embodi-ment has several advantages. The combination of annular means and protective circumferential means has the sim-plest shape, namely that of a flat ring. The mass of thesemeans is minimal, which ma~ be important in order to mini-mize the mass inertia and the mass eccentricity of a rapidly rotating storage disc. There are no portions which project from the flat side of the substrate which should
2~ face the optical write unit of an apparatus. Thus, contact between the circumferential means on a rotating storage disc and the write unit is precluded.
However, it is also possible to employ a combina-~ion of annular means and circumferential means having a ~5 cross-section in the form of, for example, a letter T
lyin~ on its side, as in the known storage disc, or a letter L lying on its side. Through plastic deformation the additional portions then formed on the outer wall of the circumferential means may contribute substantially to the absorption of impact energy, in particular if this impact face acts at an angle to the substrate.
Storage discs which are not accommodated in cassettes may be employed for simple applications. Then, but also in other cases, it may be advantageous to use an embodiment of the invention which is characterized in that the protective circumferential means are provided with portions which extend around the outer circumference of 7~
the storage disc and over the flat side of said disc situ-ated opposite the annular means. As a result of this the movement of the optical devices with which the storage disc cooperates may be obstructed but this is no-t neces-sarily always so, in particular if the associated appar-atus is constructed to allow for the said shape of the cir-cumferential means. In the above embodiment the circum-ferential means of the storage disc also provides some pro-tection if the storage disc is dropped in a direction 1~ perpendicular to its surface. It also protects the sub-strate surface against scratching when the storage disc is laid down.
If the storage disc is of a type in which the cover is made of a different material than the substrate, for e~ample as described in N.V. Philips' Gloeilampenfabrieken Canadian Patent Applications 4~6,584 and 446,58S, which were filed on February 2, 1984 and which issued as Canadian Patents 1,211,558 and 1,211,559 on Sept. 16, 1986, it may be advantageous to use a further embodiment of the inven-2~ tion in which the cover has a larger outer diameter thanthe substrate and in which the portion of the cover which projects from the substrate serves as the protective cir-cumferential means. In the optically readable storage discs in accordance with the Applicant's previous ~ppli-~5 ~ations the cover is made of, for example, a thin aluminium sheet material. Such a material is particularly suitable ~r ~bsorbin~ local shocks because it has a comparatively low resistance to plastic deformation and can thus absorb the impact energy.
Embodiments of the invention will now be described in more detail, by way of example, with reference to the drawing, in which:
Figure 1 is a perspective view, partly sectional view, of a storage disc which is a first embodiment of the invention, Figure 2 is a similar view of a second embodimentof the invention, 7~
PHN 109~3 6 Figure 3 is a similar view of a third embodiment of the invention, and Figure 4 is a similar view of a fourth embodiment of the invention.
In the various Figures corresponding parts bear the reference numerals to which the Figure numbers have been prefixed.
The optically readable storage disc shown in Figure 1 comprises a transparent substrate 11 having flat sides 17 and 18 and a circular periphery 19. The flat side 17 carries a recording layer 12 which can be modified locally by means of a radiation beam. Spaced from the r~cording layer 12 a cover disc 13 is secured to the sub-strate 11 by annular means comprising an annular spacer 16, so as to form a sealed space 14 enclosed between the sub-strate and the cover disc. On the circumference of the storage disc protective circumferential means in the form of a protective annular rim 15 are arranged for protecting the substrate 11 against damaging by external forces which aet in the plane of the storage disc. The combination of the annular spacer 16 and the protective rim 15 comprises a con~pletely flat ring with an outer wall 110. Between the outer wall 110 of the protective rim 15 and the outer cir-cumferenee 19 of the substrate there are situated no means whi~h ean transmit forces which act on the outer wall 110 to the eireumferenee 19 of the substrate. The storage disc shown in Figure 1 is of a type in which the substrate 11 ~nd the cover 13 have the same diameter and are secured to eaeh other by adhesive means at their circumferences by an interposed annular spacer 16. Near the centre another annular spacer 17 is interposed. The cover 13 comprises a transparent substrate which is identical to the substrate 11 and which in the same way as the substrate 11 has been provided with a recording layer, not shown. As a result of this a double-sided storage disc is obtained and each of the two substrates constitutes a cover for the other sub-strate.
Figure 2 shows a modification of the storage disc shown in Figure l. On its circumference the protective rim 25 is provided with portions 25A which extend perpendicu-larly to the annular surface. In Figure 2 these portions form a cylindrical ring which surrounds the storage disc.
Both the protective rim 15 of the storage disc shown in Fig. 1 and the protective rim 25 of the storage disc shown in Fig. 2 have s~mmetrical shapes. This has advantages with respect to production engineering. Such annular pro-ducts can be manufactured for example by means of an impact-e~trusion process employing an annular preform of butt-welded aluminium wire. The symmetrical shape of the annular product thus formed minimizes the risk of warping due to inevitable internal stresses. Another advantage is that the overall mass distribution of the storage disc re-mains symmetrical. The cylindrical rim 25A in Fig. 2 hasan overall height which is smaller than the distance be-tween the outer surfaces of the two substrates 21 and 23.
Therefore, the protective rim will not obstruct the move-ment of the optical recording and reproducing means of an apparatus on which the storage disc is to be used. Obvi-ously the same applies to the protective rim of the storage disc shown in Fig. 1. In principle, it is possible to give the protective rim a different circumferential shape which m~y be symmetrical or asymmetrical. If the cross-sectional sha~e of the protective rim 25 shown in Fig. 2 is described ~s that of a lying T, alternative shapes may be used in the form of a lyin~ L,Y,W etc. A protective rim such as the rim 25A is better capable of absorbing impact energy acting on the circumference of the storage disc. A part of the energy can then be absorbed by plastic deformation of the annular rim. Moreover, owing to the presence of the an-nular rim, a better protection is obtained against external impact forces which do not act exactly in the plane of the storage disc but which are directed obliquely relative to this plane. External impact forces on the protective rim 15 or the protective rim 25 give rise to shear stresses in the layers of adhesive between the spacer 16 and 26, respectively and the respective substrates. In general, ~c~r~
layers of an adhesive are much ~e~E capable of withstand-ing shèar stresses than tensile stresses, so that in suc`h cases the layers of adhesive are subjected to comparatively favourable load. The annular spaces 212 and 213 situated between the circumference 29 and 214 and the inner wall 25A
may be filled, if desired, with a material which cannot transmit undesirably large forces.
The storage disc shown in Fig. 3 is of a different construction than those shown in ~igs. 1 and 2. The stor-age disc comprises a single transparen-t substrate 31 pro-vided with a radiation-sensitive layer 32. The cover 33 is made of a thin aluminium sheet formed into a shallow hat-shaped part. The trim of the hat constitutes the annular means 36 and is affixed to the substrate 31 by means of an adhesive. The protective circumferential means 35 are sprung over the edge of the substrate. The centre portion of the cover 33 is spaced from the recording layer 32, so that a sealed space 34 is formed between the substrate and the cover. Optically readable storage discs of this type ~a have been described in the Applicant's afore-mentioned Canadian Patent Applications 446,58~ and 446,585. The aluminium sheet material used is thin and is not in direct contact with the outer wall 39. Thus, impact energy acting on the circumference of the storage disc will be absorbed ~5 ~ d~formation of the circumferential means. Additional protection is provided by an elastic ring 315. This has t}la ~dc~itional advantage that the external surface 318 of the substrate 31 is protected against scratching when the stora~e disc s placed with the substrate facing down.
This ~ay happen in particular in the case of storage discs of a simpler type, for example those intended for use in perpipheral equipment of small office computers, personal computers or home computers, when the storage disc is not accommodated in a cassette. The ring 315 may be made of an elastomeric material, preferably a material with optimum damping properties. Specific elastomers such as butyl rubber have suitable properties in this respect.
Another possibility of providing a storage disc 7~
PHN. 10.943 9 resembling ~hat shown in Fig. 3 with protective circumfer-ential means is shown in Fig. 4. The storage disc shown in this Figure is practically identical to that shown in Fig. 3 except for a modification near the circumference.
The outer edge portion of the cover 44 has not ~een sprung over the substrate 41.
Various modifications are possible within the scope of the present invention. It is always preferred to provide an optimum protection of the circumference of the substrate by absorbing shocks with the aid of the protec-tive circumferential means. Care mus-t be taken that the eireumferential means eannot give rise to thermal stresses in the substrate. Plastic deformation of the protective circumferential means is a method of absorbing the energy of a shock. However, it is essential that substantially no forces can be transmitted to the circumference the sub-strate by such a design that a space is formed between the circumferenee of the substrate and the circumerential means and that this spaee does not eontain any means which can ~0 transmit undesirably lar~e impact forces. All forces, or praetieally all forces, are transmitted to a flat side or to both flat sides of the substrate or substrates. The cir-eumerential means may be modified by providing slits or apertures, not shown, so that they may be deformed more 2~ ~asily. Instead of providing eircumferential means having a eontinuous eircumference, the circumference may thus be ~ivided in a plurality of parts which may each be deformed ~ndividùally. Any resulting remaining deformation of the proteetive eireumferential means will generally not inter-fere with further use of the storage disc and is certainlypreferable over damage to the substrate. When neeessary, it is often possible to restore at least approxima-tely damaged circumferential means to the original shape. Elas-tie deformation may provide additional protection. A stor-age disc which drops on its circumference may bounce backand subsequently eome down in a less undesirable orienta-tion. Some elastomers such as the afore-mentioned butyl rubber, are well-known for their damping and eonsequently PHN 1~43 10 shock-absorbing properties, so that they are suitable for the present purpose.
The proteetive circumferential means of the stor-age disc in accordance with the invention may also be used for balancing the storage disc when neeessary. This poten-tial use forms the subject of the Applicant's Canadian Patent Application 473,765 whieh was filed on February 7, 1~85. Locally, small balancing masses may be provided, which could locally transmit impact forces from the cir-1~ eumferenee to the substrate. Although this is preferablyprecluded, such a small risk may be acceptable.
However, it is also possible to employ a combina-~ion of annular means and circumferential means having a ~5 cross-section in the form of, for example, a letter T
lyin~ on its side, as in the known storage disc, or a letter L lying on its side. Through plastic deformation the additional portions then formed on the outer wall of the circumferential means may contribute substantially to the absorption of impact energy, in particular if this impact face acts at an angle to the substrate.
Storage discs which are not accommodated in cassettes may be employed for simple applications. Then, but also in other cases, it may be advantageous to use an embodiment of the invention which is characterized in that the protective circumferential means are provided with portions which extend around the outer circumference of 7~
the storage disc and over the flat side of said disc situ-ated opposite the annular means. As a result of this the movement of the optical devices with which the storage disc cooperates may be obstructed but this is no-t neces-sarily always so, in particular if the associated appar-atus is constructed to allow for the said shape of the cir-cumferential means. In the above embodiment the circum-ferential means of the storage disc also provides some pro-tection if the storage disc is dropped in a direction 1~ perpendicular to its surface. It also protects the sub-strate surface against scratching when the storage disc is laid down.
If the storage disc is of a type in which the cover is made of a different material than the substrate, for e~ample as described in N.V. Philips' Gloeilampenfabrieken Canadian Patent Applications 4~6,584 and 446,58S, which were filed on February 2, 1984 and which issued as Canadian Patents 1,211,558 and 1,211,559 on Sept. 16, 1986, it may be advantageous to use a further embodiment of the inven-2~ tion in which the cover has a larger outer diameter thanthe substrate and in which the portion of the cover which projects from the substrate serves as the protective cir-cumferential means. In the optically readable storage discs in accordance with the Applicant's previous ~ppli-~5 ~ations the cover is made of, for example, a thin aluminium sheet material. Such a material is particularly suitable ~r ~bsorbin~ local shocks because it has a comparatively low resistance to plastic deformation and can thus absorb the impact energy.
Embodiments of the invention will now be described in more detail, by way of example, with reference to the drawing, in which:
Figure 1 is a perspective view, partly sectional view, of a storage disc which is a first embodiment of the invention, Figure 2 is a similar view of a second embodimentof the invention, 7~
PHN 109~3 6 Figure 3 is a similar view of a third embodiment of the invention, and Figure 4 is a similar view of a fourth embodiment of the invention.
In the various Figures corresponding parts bear the reference numerals to which the Figure numbers have been prefixed.
The optically readable storage disc shown in Figure 1 comprises a transparent substrate 11 having flat sides 17 and 18 and a circular periphery 19. The flat side 17 carries a recording layer 12 which can be modified locally by means of a radiation beam. Spaced from the r~cording layer 12 a cover disc 13 is secured to the sub-strate 11 by annular means comprising an annular spacer 16, so as to form a sealed space 14 enclosed between the sub-strate and the cover disc. On the circumference of the storage disc protective circumferential means in the form of a protective annular rim 15 are arranged for protecting the substrate 11 against damaging by external forces which aet in the plane of the storage disc. The combination of the annular spacer 16 and the protective rim 15 comprises a con~pletely flat ring with an outer wall 110. Between the outer wall 110 of the protective rim 15 and the outer cir-cumferenee 19 of the substrate there are situated no means whi~h ean transmit forces which act on the outer wall 110 to the eireumferenee 19 of the substrate. The storage disc shown in Figure 1 is of a type in which the substrate 11 ~nd the cover 13 have the same diameter and are secured to eaeh other by adhesive means at their circumferences by an interposed annular spacer 16. Near the centre another annular spacer 17 is interposed. The cover 13 comprises a transparent substrate which is identical to the substrate 11 and which in the same way as the substrate 11 has been provided with a recording layer, not shown. As a result of this a double-sided storage disc is obtained and each of the two substrates constitutes a cover for the other sub-strate.
Figure 2 shows a modification of the storage disc shown in Figure l. On its circumference the protective rim 25 is provided with portions 25A which extend perpendicu-larly to the annular surface. In Figure 2 these portions form a cylindrical ring which surrounds the storage disc.
Both the protective rim 15 of the storage disc shown in Fig. 1 and the protective rim 25 of the storage disc shown in Fig. 2 have s~mmetrical shapes. This has advantages with respect to production engineering. Such annular pro-ducts can be manufactured for example by means of an impact-e~trusion process employing an annular preform of butt-welded aluminium wire. The symmetrical shape of the annular product thus formed minimizes the risk of warping due to inevitable internal stresses. Another advantage is that the overall mass distribution of the storage disc re-mains symmetrical. The cylindrical rim 25A in Fig. 2 hasan overall height which is smaller than the distance be-tween the outer surfaces of the two substrates 21 and 23.
Therefore, the protective rim will not obstruct the move-ment of the optical recording and reproducing means of an apparatus on which the storage disc is to be used. Obvi-ously the same applies to the protective rim of the storage disc shown in Fig. 1. In principle, it is possible to give the protective rim a different circumferential shape which m~y be symmetrical or asymmetrical. If the cross-sectional sha~e of the protective rim 25 shown in Fig. 2 is described ~s that of a lying T, alternative shapes may be used in the form of a lyin~ L,Y,W etc. A protective rim such as the rim 25A is better capable of absorbing impact energy acting on the circumference of the storage disc. A part of the energy can then be absorbed by plastic deformation of the annular rim. Moreover, owing to the presence of the an-nular rim, a better protection is obtained against external impact forces which do not act exactly in the plane of the storage disc but which are directed obliquely relative to this plane. External impact forces on the protective rim 15 or the protective rim 25 give rise to shear stresses in the layers of adhesive between the spacer 16 and 26, respectively and the respective substrates. In general, ~c~r~
layers of an adhesive are much ~e~E capable of withstand-ing shèar stresses than tensile stresses, so that in suc`h cases the layers of adhesive are subjected to comparatively favourable load. The annular spaces 212 and 213 situated between the circumference 29 and 214 and the inner wall 25A
may be filled, if desired, with a material which cannot transmit undesirably large forces.
The storage disc shown in Fig. 3 is of a different construction than those shown in ~igs. 1 and 2. The stor-age disc comprises a single transparen-t substrate 31 pro-vided with a radiation-sensitive layer 32. The cover 33 is made of a thin aluminium sheet formed into a shallow hat-shaped part. The trim of the hat constitutes the annular means 36 and is affixed to the substrate 31 by means of an adhesive. The protective circumferential means 35 are sprung over the edge of the substrate. The centre portion of the cover 33 is spaced from the recording layer 32, so that a sealed space 34 is formed between the substrate and the cover. Optically readable storage discs of this type ~a have been described in the Applicant's afore-mentioned Canadian Patent Applications 446,58~ and 446,585. The aluminium sheet material used is thin and is not in direct contact with the outer wall 39. Thus, impact energy acting on the circumference of the storage disc will be absorbed ~5 ~ d~formation of the circumferential means. Additional protection is provided by an elastic ring 315. This has t}la ~dc~itional advantage that the external surface 318 of the substrate 31 is protected against scratching when the stora~e disc s placed with the substrate facing down.
This ~ay happen in particular in the case of storage discs of a simpler type, for example those intended for use in perpipheral equipment of small office computers, personal computers or home computers, when the storage disc is not accommodated in a cassette. The ring 315 may be made of an elastomeric material, preferably a material with optimum damping properties. Specific elastomers such as butyl rubber have suitable properties in this respect.
Another possibility of providing a storage disc 7~
PHN. 10.943 9 resembling ~hat shown in Fig. 3 with protective circumfer-ential means is shown in Fig. 4. The storage disc shown in this Figure is practically identical to that shown in Fig. 3 except for a modification near the circumference.
The outer edge portion of the cover 44 has not ~een sprung over the substrate 41.
Various modifications are possible within the scope of the present invention. It is always preferred to provide an optimum protection of the circumference of the substrate by absorbing shocks with the aid of the protec-tive circumferential means. Care mus-t be taken that the eireumferential means eannot give rise to thermal stresses in the substrate. Plastic deformation of the protective circumferential means is a method of absorbing the energy of a shock. However, it is essential that substantially no forces can be transmitted to the circumference the sub-strate by such a design that a space is formed between the circumferenee of the substrate and the circumerential means and that this spaee does not eontain any means which can ~0 transmit undesirably lar~e impact forces. All forces, or praetieally all forces, are transmitted to a flat side or to both flat sides of the substrate or substrates. The cir-eumerential means may be modified by providing slits or apertures, not shown, so that they may be deformed more 2~ ~asily. Instead of providing eircumferential means having a eontinuous eircumference, the circumference may thus be ~ivided in a plurality of parts which may each be deformed ~ndividùally. Any resulting remaining deformation of the proteetive eireumferential means will generally not inter-fere with further use of the storage disc and is certainlypreferable over damage to the substrate. When neeessary, it is often possible to restore at least approxima-tely damaged circumferential means to the original shape. Elas-tie deformation may provide additional protection. A stor-age disc which drops on its circumference may bounce backand subsequently eome down in a less undesirable orienta-tion. Some elastomers such as the afore-mentioned butyl rubber, are well-known for their damping and eonsequently PHN 1~43 10 shock-absorbing properties, so that they are suitable for the present purpose.
The proteetive circumferential means of the stor-age disc in accordance with the invention may also be used for balancing the storage disc when neeessary. This poten-tial use forms the subject of the Applicant's Canadian Patent Application 473,765 whieh was filed on February 7, 1~85. Locally, small balancing masses may be provided, which could locally transmit impact forces from the cir-1~ eumferenee to the substrate. Although this is preferablyprecluded, such a small risk may be acceptable.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An optically readable information storage disc comprising a transparent, planar substrate with flat sides and a circular periphery, a recording layer which can be modified locally by means of a radiation beam, said record-ing layer being disposed on one of said flat sides of said substrate, a disc-shaped member in superposed relationship with said recording layer, annular means disposed between said disc-shaped member and said substrate for maintaining said member spaced from at least a portion of said sub-strate with said recording layer thereon so that said recording layer is disposed between said member and said substrate, means for securing together said annular means, said member and said substrate, said annular means having a protective rim which is spaced from said circular periphery of said substrate in a direction parallel to the plane of said substrate and extends about said substrate so as to form a space between said circular periphery and said pro-tective rim which is substantially free of intermediate material which, in ease of deformation of said protective rim, can transmit to said circular periphery a force which acts in the plane of said substrate, which is directed to the center of the substrate and which has a magnitude sufficient to damage the substrate.
2. An optically readable storage disc as claimed in Claim 1, characterized in that said annular means and cir-cumferential means together constitute a flat ring having an outer diameter which is larger than that of the sub-strate.
3. An optically readable storage disc as claimed in Claim 1, characterized in that the circumferential means comprise portions which extend around the circumference of the substrate and beyond the flat side of the substrate which is situated opposite the annular means.
4. An optically readable storage disc as claimed in Claim 1, of a type in which the cover is made of a dif-ferent material than the substrate, characterized in that the cover has a larger outer diameter than the sub-strate and the portion of the cover which projects beyond the substrate is provided with an annular flange which serves as the circumferential means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8400476 | 1984-02-14 | ||
| NL8400476A NL8400476A (en) | 1984-02-14 | 1984-02-14 | OPTICALLY READABLE MEMORY DRIVE. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1241744A true CA1241744A (en) | 1988-09-06 |
Family
ID=19843488
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000473768A Expired CA1241744A (en) | 1984-02-14 | 1985-02-07 | Protective rim for storage discs |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS60140235U (en) |
| BE (1) | BE901719A (en) |
| CA (1) | CA1241744A (en) |
| DD (1) | DD228381A5 (en) |
| DE (1) | DE3505015A1 (en) |
| ES (1) | ES8606710A1 (en) |
| FR (1) | FR2559607A1 (en) |
| GB (1) | GB2155684B (en) |
| IT (1) | IT1183232B (en) |
| NL (1) | NL8400476A (en) |
| SU (1) | SU1487826A3 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2343784B (en) * | 1998-11-16 | 2001-08-01 | Leung Ching Yuen | Irregular optical disc |
| US20020136155A1 (en) * | 2001-03-06 | 2002-09-26 | Chieh-Ho Chen | CD safe to hold |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE190908C (en) * | ||||
| DE203656C (en) * | ||||
| GB335768A (en) * | 1929-10-24 | 1930-10-02 | Jacoviac Maurice | Improvements in protecting devices for gramophone disc records |
| DE883811C (en) * | 1951-06-08 | 1953-07-20 | Hermann Geiselhart | Ring made of rubber as plate protection |
| US4331966A (en) * | 1980-10-06 | 1982-05-25 | Storage Technology Corporation | Information storage device and method of forming same |
| JPS5774842A (en) * | 1980-10-24 | 1982-05-11 | Mitsubishi Electric Corp | Optical information recording disk |
| US4376963A (en) * | 1980-12-19 | 1983-03-15 | International Business Machines Corporation | Composite magnetic recording disk |
| JPS57150155A (en) * | 1981-03-09 | 1982-09-16 | Matsushita Electric Ind Co Ltd | Magnetooptic disc |
| JPS57172541A (en) * | 1981-04-15 | 1982-10-23 | Toshiba Corp | Information storage medium |
| JPS57172542A (en) * | 1981-04-15 | 1982-10-23 | Toshiba Corp | Information storage medium |
| FR2528216B1 (en) * | 1982-06-08 | 1988-01-08 | Thomson Csf | PROTECTED OPTICAL DISC WITH FREE LAYER |
| JPS5987636A (en) * | 1982-11-10 | 1984-05-21 | Toshiba Corp | Information storage medium |
-
1984
- 1984-02-14 NL NL8400476A patent/NL8400476A/en not_active Application Discontinuation
-
1985
- 1985-02-07 CA CA000473768A patent/CA1241744A/en not_active Expired
- 1985-02-11 IT IT19458/85A patent/IT1183232B/en active
- 1985-02-11 ES ES540285A patent/ES8606710A1/en not_active Expired
- 1985-02-12 BE BE0/214507A patent/BE901719A/en not_active IP Right Cessation
- 1985-02-12 FR FR8501934A patent/FR2559607A1/en active Pending
- 1985-02-12 DD DD85273212A patent/DD228381A5/en unknown
- 1985-02-13 GB GB08503678A patent/GB2155684B/en not_active Expired
- 1985-02-13 SU SU853862706A patent/SU1487826A3/en active
- 1985-02-13 JP JP1985017893U patent/JPS60140235U/en active Pending
- 1985-02-14 DE DE19853505015 patent/DE3505015A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| NL8400476A (en) | 1985-09-02 |
| DD228381A5 (en) | 1985-10-09 |
| IT8519458A0 (en) | 1985-02-11 |
| GB8503678D0 (en) | 1985-03-13 |
| GB2155684A (en) | 1985-09-25 |
| IT1183232B (en) | 1987-10-15 |
| FR2559607A1 (en) | 1985-08-16 |
| ES8606710A1 (en) | 1986-04-01 |
| SU1487826A3 (en) | 1989-06-15 |
| BE901719A (en) | 1985-08-12 |
| DE3505015A1 (en) | 1985-08-14 |
| JPS60140235U (en) | 1985-09-17 |
| GB2155684B (en) | 1988-11-02 |
| ES540285A0 (en) | 1986-04-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AU2018201419B2 (en) | Multi-Buffering Safety Helmet | |
| CA1094685A (en) | Radiation-sensitive record with protected sensitive surface | |
| EP0049821B1 (en) | Data recording medium | |
| CA1241441A (en) | Optically readable storage disc | |
| US4564850A (en) | Radiation-sensitive record disc with improved internal structure | |
| EP3391765B1 (en) | Safety helmet with rotary impact buffering function | |
| CA1241744A (en) | Protective rim for storage discs | |
| EP0119809B1 (en) | Cover assembly for optical recording medium | |
| US6249509B1 (en) | Optical device with protective cover | |
| US3543922A (en) | Container with external shock absorbing structure | |
| KR910006083B1 (en) | Process for producing information recording discs | |
| US4742421A (en) | Magnetic recording disc having tensioned and elastically-supported recording surface | |
| CN2447910Y (en) | CD storage case | |
| JPS61233481A (en) | Cartridge | |
| JP2550869B2 (en) | Magnetic disk drive | |
| EP1733396A1 (en) | Recording medium storage package having improved rosette | |
| CN1003100B (en) | Optically readable storage disc | |
| JPS5971145A (en) | Information recording medium | |
| JPH0430650Y2 (en) | ||
| JPS62248180A (en) | Optical disk | |
| JPS63268146A (en) | Optical disk | |
| JPH0433556Y2 (en) | ||
| JPH03125349A (en) | Optical information recording carrier | |
| JPH01208745A (en) | Information storing medium | |
| JPH01199335A (en) | Optical disk medium |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |