Disc-shaped information carrier having an insert piece provided with a central bore

Abstract: Round disc-shaped information carrier (12), e.g. a compact-disc (CD), videodisc or the like, adapted to be carried during recording and/or playback by support means provided with a central axis snugly fitting in a bore, present in the centre of the information carrier, the bore being present in an insert piece (14, 14) positioned in a larger bore (13) present in the information carrier, said insert piece comprising a generally cylindrical part (15) extending through the bore present in the information carrier and flanges (16) present at the ends of said cylindrical part, said flanges substantially covering the edges of the bore present in the information carrier.

Description: The invention relates to a round disc-shaped information carrier having a bore at the center of it, in combination with an insert piece comprising a generally cylindrical part extending through the bore and substantially contacting the entire inside edge of the bore, the combination being adapted to be rotated, in a recording and/or reproducing apparatus by drive means having a spindle on which the information carrier is clamped, said spindle snugly fitting in in a bore present in the insert piece. WO 84/04839 and DE-A-3 441 521 both relate to a combination of a round disc-shaped information carrier in combination with an insert piece as defined herein above. It is noted that US-A-2 806 704 discloses a gramophone record provided with an insert piece so as to make the combination of record and insert piece suitable for being clamped on a gramophone turntable. The insert piece snap-fits into the central hole of the record and is to that end provided with slots. These slots, however, extend from the outer peripheral wall of the insert piece in a radially inward direction. During the manufacture by means of press moulding techniques of such an information carrier a central bore is punched out, prior to the removal from a press mould of the ready and cooled product by means of a punching operation. With such an operation it can not always be avoided to a sufficient degree that the final product exhibits a bore of which the quality and the accuracy leaves to be desired. Caused by the punching out of the bore in the thermal plastic material in its still warm, and therefore readily deformable condition, the edge of the bore is pressed away a little to one side, owing to which this edge exhibits an undesirable sharpness or even a somewhat rough structure. In order to solve this problem the invention provides an information carrier of the type described, which is characterised in that said information carrier is made of a stiff material by injection moulding and in that the insert piece consists of an axially slotted hollow cylindrical body having at one end a closed flange and at its other end a radially outwardly extending peripheral rib segmented by the axial slots, said axial slots extending partially into the flange from its inside edge in an outward direction and the rib segments forming together with the flange a gripping channel such that the insert piece snap-fits into the information carrier. The invention also allows press moulding by means of other techniques, e.g. using a ring of small injection openings around a bore. This technique is known as "refuse-free moulding". The fact that this technique is not applied for most information carriers is caused by the fact that the injection points can not or only with a lot of effort be removed in an after-treatment. Now, according to the invention, the insert piece can cover the injection points, so that one can use the refuse-less injection method. It will be clear that such a method has the advantage of using less material. E.g. for information carriers usable from both sides the insert piece may have a symmetrical construction. In this case one may think of an embodiment exhibiting the special feature that the insert piece comprises two parts, the one of which is brought through the bore present in the information carrier from the one side and the other of which from the other side. If both parts are identical, one has only have to use one press mould for the insert piece. The invention will now be explained with reference to the drawing of two arbitrary embodiments to which the invention is not limited. In the drawing: Fig. 1 shows an information carrier having an insert piece and a capstan provided with support means therefore; and Fig. 2 shows an information carrier provided with an alternative embodiment of an insert piece consisting of two identical parts. Fig. 1 shows an information carrier 1, e.g. a compact-disc, that can be carried and during operation rotatably driven by means of a central driving spindle 2, and a support edge 3 coupled therewith. The driving spindle 2 exhibits a stepwise structure having two conically tapering circumferential surfaces 4, 5, for searching and centering the information carrier 1. The information carrier 1 is provided with a central bore 6, in which an insert piece 7 is positioned. This insert piece 7 is provided with a central bore 8, the diameter of which corresponds exactly with the diameter of the lower part 8 of spindle 2. The insert piece 7 exhibits a ring of six resilient locking edges 9, by means of which the insert piece 7 can be pressed into the bore 6 of the information carrier 1, whilst pressing inwardly the locking edges 9, which after having passed the bore in outward direction to form a strong coupling between the insert piece 7 and the information carrier 1 together with a flange edge 10 positioned at the other side. Locking edges 9 are provided with conical searching edges 20 at their edge zones of their upper surfaces extending in outward direction. With reference to the above description it will be clear that the central bore 8 was, up to now, the diameter of the central bore in information carrier 1. With the invention the information carrier 1 has to be provided with a bore having a larger diameter in connection with the thickness at both sides of the generally cylinder-shaped vertical wall part 11 of the insert piece 7. Fig. 2 shows an insert piece consisting of two identical parts 21 and provided with the same locking edges as shown in fig. 1, in which, however, each part 21 is provided with only three equidistant locking edges 9, leaving free intermediate zones 22 which extend over a somewhat larger angle than the locking edges 9 in such a way, that a locking edge of the one part 21 fits in the free zone of the other element. Thus in a first step the one part 21 can lockingly be coupled with the information carrier 12 according to fig. 1 and in a next-following step the other part 21 can be coupled with that information carrier 12.

Claims: Round disc-shaped information carrier (1) having a bore (6) at the center of it, in combination with an insert piece (7) comprising a generally cylindrical part extending through the bore (6) and substantially contacting the entire inside edge of the bore (6), the combination (1, 7) being adapted to be rotated, in a recording and/or reproducing apparatus by drive means having a spindle (2) on which the information carrier (1) is clamped, said spindle (2) snugly fitting in in a bore present in the insert piece (7), characterized in that said information carrier (1) is made of a stiff material by injection moulding and in that the insert piece (7) consists of an axially slotted hollow cylindrical body having at one end a closed flange (10) and at its other end a radially outwardly extending peripheral rib (9) segmented by the axial slots, said axial slots extending partially into the flange (10) from its inside edge in an outward direction and the rib segments (9) forming together with the flange (10) a gripping channel such that the insert piece (7) snap-fits into the information carrier (1). Information carrier according to claim 1, characterized in that the insert piece (7) comprises two parts (14,14), the one of which is brought through the bore (6) present in the information carrier (1) from the one side and the other of which from the other side. Information carrier according to claim 2, characterized in that both pieces (21,21) are identical. Insert piece as part of the combination as defined in any one of the preceding claims.

Inventors: VAN POORTEN ANTONIUS, VAN POORTEN, ANTONIUS
Applicants: GPT AXXICON BV, GPT AXXICON B.V.
Application year: 1986
Main classification: G11B23
IPC codes: G11B23