Such a packaging unit is described in the publication WO/97/38919. It consists of an approximately square, flat casing and a kind of envelope inserted therein in a drawer-like manner, which envelope is obstructed from being extracted more than approximately half of its size. The envelope is preferably punched in one piece and folded, and also presents a separation plate and an underlying bottom plate. A disc can be put on top of the separation plate and is retained thereon by at least one flap in the separation plate, which is folded over the edge of the disc. By means of one or more flaps in the separation plate and a lid flap, the disc is kept in place in the packaging unit, almost fixed. A folder, so-called booklet, can be inserted between the separation plate and the bottom plate.

It has appeared that a certain disadvantage with this construction arises at some extreme climate conditions. Due to the downwardly folded retaining flaps, which by necessity cannot be placed completely symmetrically and, if placed e. g. at the open- ing end, also would interfere with taking out and reinserting the disc, a certain bend- ing moment will rest against the disc. This bending moment may be magnified due to the fact that the compact disc of necessity also supports itself against the fondation with a ring, casted in the compact disc, around the middle hole. When storing at high temperatures during an extended time period, this can lead to a permanent, plastic bending deformation, so that the disc, when being played,"flaps" and does not keep a constant distance to a recording head. The size of this effect is dependent upon the material used, the time during which an elastic deformation of the disc lasts, and the storing temperature. This means that also a very good material can be permanently deformed if the storing time is long, even if the temperature is a

moderate room temperature. For a simpler plastic material, where the general requirements are lower, the deformation problem is greater.

According to the invention, this problem is solved and the advantages of the inven- tion is obtained by a packaging unit of the kind mentioned in the beginning,- presenting the features stated in the characterizing part of claim 1. Thereby it is obtained, among other things, that the packed disc is not subjected to other forces than those arising due to its own mass and weight. When the disc in the packaging unit is stored standing, something, which must be considered to be normal, these forces can be regarded as negligible. At least as long as the packaging unit itself is not subjected to outer deformations, the deformation damages in question can thereby hardly arise any more.

According to a preferred embodiment of the invention, it is additionally desired to avoid, as far as possible, that the information-carrying layer of the disc touches the foundation, making friction damages possible. It is in itself enough if elevated supporting elements at the periphery support the disc at areas that are unrecorded.

When discs are recorded, starting from close to the centre and outwards, the margin at the periphery will often be wide. However, according to valid standards, the margin does not have to be wider than 1.7 mm, concerning the normal compact disc and similar standard discs. To ensure, in this case, that the information layer clears the foundation, it is arranged in an alternative embodiment the supporting elements as elevations with its highest points located on a circle, which is larger than the outer periphery of the disc, whereby the edge of the disc will come to rest against the parts of these elevations that face and slope towards the centre.

The remaining sub-claims state further preferred embodiments of the invention.

The invention will now be described with reference to a non-limiting embodiment example with the aid of the attached drawings. Fig. 1 shows a material for an enve- lope. Fig. 2 shows a material for a casing for the envelope. Fig. 3 shows, partly

sectioned, a folded and composed device with a compact disc inserted. Fig. 4 shows a second embodiment of a material for an envelope. Fig. 5 shows a third embodiment of a material for an envelope. Fig. 6 shows schematically and in a partial sectioned view how a compact disc is supported in an envelope according to the second or the third embodiment. Fig. 7 shows a readily folded envelope according to the second embodiment, with a disc inserted.

The material of cardboard or the like, shown in Fig. 1, has a bottom plate 80, over which a lid flap 73 is folded via folds 71,72 which determine the thickness of the envelope, a separation plate 74 which is folded over the bottom plate and which can have a circular contour, and flaps 76,76'and 76". The folding line 75 of the separa- tion plate, forming a boundary between the bottom plate 80 and the separation plate 74, is located outside both folding lines 77,78 belonging to the punched flap 76, and the distance of which approximately corresponds to the thickness of the comp- leted envelope, as well as the fold lines 71,72 mentioned earlier. The flap 76 also forms a blocking flap, this being addressed closer here below. A folding line 79 serves to ease the control of a packed disc, after the partial extraction of the envelope from the casing.

The material for a casing, shown in Fig. 2, has a bottom part 84 and an upper part of the same size, both corresponding and adapted to insertion of the bottom plate 80 with parts of the envelope part belonging thereto. Assembled and glued together via side flaps, it has an inwardly folded flap 81 at its opening. This flap will spring downwards, and also the flap 76 (Fig. 1) will spring upwards, and at extraction they will hook onto each other and prevent a continued extraction. This appears clearer in the partly sectioned view in Fig. 3, which shows a partly extracted envelope with a separation plate, supporting a disc P.

For a good grip at the extraction of the envelope, this has a hollow 85 (see Fig. 3), which, in the inserted position, coincides with a hollow 89 (see Fig. 2) in the casing at its opening.

In Fig. 3, it also appears clearly how the disc P is prevented from sideway motions, by means of the flaps 76,76'and 76", and one can easily understand that, in an inserted position, a further side obstacle will be formed by the downwardly folded lid flap 73, and also the narrow walls of the casing.

According to the present invention, small stampings 86 have been made on the edge of the separation plate, according to Fig. 1, which stampings create elevations at the edges, against which the disc rests at the outer periphery. Additionally, the fold notches for the flaps have, which is apparent in Fig. 1, been doubled, which means that they no longer squeeze an inserted disc against the surface of the separation plate.

According to a preferred embodiment, the elevations are arranged as bosses, with its centres located outside the edge of the disc, so that the disc rests against the bosses at inwardly sloping parts. As is apparent from Fig. 4 and 5, this means that the separation plate 74'cannot have the same form as the disc, instead, at least in some parts, it will extend beyond the disc. Thereby, in Fig. 4, such bosses 88 are pressed into the cardboard material, something, which can be performed in connection with the punching itself. Otherwise, the material in Fig. 4 resembles the material in Fig.

1. The material in Fig. 5 has additionally its bottom plate provided with bosses 89, which have to be pressed out from the opposite direction, generally causing a further manufacturing stage for the material.

Alternatively, the booklet-meaning the usually enclosed folder-may possibly be provided with corresponding bosses (not shown in the figure).

Fig. 6 shows schematically how a disc is located according to the preferred embodiment of the invention. A disc P is put on a separating plate 74', and what is shown is only a part of the disc P with its circular rim R, extending around the centre which is not shown, and an information area I, located outside the rim, and

also the margin part M, which is empty of information, and according to valid standards may not be below 1.7 mm. The figure is essentially to scale. A boss 88 has its symmetry line 90 located just outside the edge of the disc, resulting in that the edge of the disc will be supported against the inwardly sloping part of the boss 88, which thereby supports the disc together with the rim R. From the figure it can also be seen that a certain small side movement may be permitted, within the manufacturing accuracy obtained regarding the location of the tongues 76', 76"and 73, in particular.

Fig. 7 shows an envelope prior to insertion in a casing, with a disc P supported by bosses 8 and by the (not shown) circular rim at the middle. Apart from what has been described earlier, it should be noticed that the bottom part has side recesses 100, which are located in front of the side edges of the disc, making possible a firm grip across the disc P, when the envelope is extracted to the stop position.

In most cases the space under the separating plate is readily used for packing a small folder, which, concerning music, may contain texts, different articles and other things, as well as, for computer discs, short manual-like descriptions. However, according to an aspect of the invention, the possibility to, in a corresponding pro- tective way, pack a second compact disc under the separating plate is foreseen. It is then suitable also in this case, consequently on the bottom plate 80, to arrange elevations of the same nature, such as bosses 87, as shown in Fig. 1. Taken into consideration that the material in Fig. 1 shall be folded, the bosses must, if they are to be formed as stampings, be stamped in opposite directions, since both the bosses 86 and the bosses 87 must be directed upwards in the completed envelope according to Fig. 3. In case no special flaps are arranged for retaining the disc, which is unnecessary if the disc is not fully recorded and consequently has a wider unrecorded peripherical margin, it is suitable to make the supporting elements larger in the bottom plate, so that they execute their supporting task even despite the greater movability, especially in the extraction direction of the envelope.

Even if, at present, a preferred way to obtain supporting elements such as supporting bosses 86 and 87,88,89, respectively, is to use stamping tools, preferably with a plunger and a dye, the supporting elements can be arranged in many different ways, for example by attaching drops of adhesive, arranged by _ small, cross-cutting flaps, etc., all being variations that are immediately available to the person skilled in the art.