DE20111163U1 - Accessory part for information carriers, in particular compact disc or digital versatile disc - Google Patents

Description

Pure high fidelity

Werner Clemens

Heerstrasse 39

41542 Dormagen 2. Wed 2001

Accessory for information media, especially compact disc or Digital Versatile Disc

The invention relates to an accessory which is placed on an information carrier which can be scanned by means of an optoelectronic scanning system, in particular a compact disc (CD) or a digital versatile disc (DVD), with a carrier consisting of metallized plastic which has a side which can be scanned by a laser beam and a back side provided with a print.

The compact disc and the digital versatile disc are circular, disc-shaped information carriers made of metallized plastic, recorded on one side. The music or image information is contained beneath a transparent plastic protective layer in the form of a dense sequence of microscopically small depressions, so-called pits, which are arranged in a spiral. These depressions represent the "images" of a digital pulse code modulation signal into which the analog acoustic or optical information is converted during music or video recording. In the case of the compact disc, this pulse code modulation signal contains not only the music information, but also information about the separation of the two stereo channels and an address section that enables direct access to a specific piece of music on the compact disc.

When playing a compact disc or digital versatile disc, the digital information is read using an optoelectronic scanning system that scans the pits without contact using the focused light beam of a semiconductor laser. When the laser beam hits a pit, it is reflected differently than from the plane between the pits. The laser beam, modulated by the information pattern of the compact disc or digital versatile disc, is directed to a photodiode via a semi-transparent prism.

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There, the light pulses are converted into digital electrical signals, from which the original sound information, the stereo sound signal, is reconstructed in a downstream digital-analog converter. The analog stereo sound signal is then audible in the loudspeaker after amplification. In a similar way, the original image information is recovered as color television images in the Digital Versatile Disc using digital electronics.

The main production stages of a compact disc or digital versatile disc include mastering, electroplating, pressing, metallizing, varnishing, punching and printing. During mastering, a circular, perfectly flat glass disc (glass father) with a light-sensitive coating is exposed to the pattern of the pits by a laser beam. After the exposed parts have been etched away, the disc is coated with silver (metal father). A negative (metal mother) is then produced electroplatingly in a nickel bath, from which several matrices are made that serve as molds for the automatic pressing of the compact disc or digital versatile disc. After pressing, the side with the pit pattern is vapor-coated with aluminum in a vacuum to create a reflective layer. A lacquer coating made of transparent plastic is then applied to the aluminum layer to protect it. The back of the compact disc or digital versatile disc is usually provided with a label printed.

The applicant has determined that when playing conventional compact disks or digital versatile disks, unwanted light reflections or those impaired by the printing (label) often occur. If one looks at conventional compact disks or

If you look at a Digital Versatile Disk from the side to be scanned by the laser beam against a bright light source, you can often see that the writing and/or images on the print are more or less clearly visible through the thin aluminum coating. Part of the laser light shines through the aluminum coating and is reflected at the bottom of the print with varying intensities due to the writing or images on the print. In order to avoid any impairment of the sound or image quality due to such unwanted light reflections,

To avoid this, special electronic error correction circuits are used, which are also intended to minimize the influence of dust, scratches and surface dirt on the playback quality.

The present invention is based on the object of producing an accessory article (White Mirror No. 1) which, when placed on a conventional information carrier, provides a more detailed reproduction quality.

This object is achieved according to the invention in a generic information carrier by placing the accessory part (White Mirror No. 1) from above on the printed label. This means that it is no longer possible for the light from the laser to shine through the label.

The opaque, non-reflective layer prevents the unwanted reflections mentioned above, so that the playback quality of an information carrier coated in this way is significantly improved. Tests by the applicant have shown that a compact disc coated in accordance with the invention delivers a more detailed, high-resolution sound.

A preferred embodiment of the accessory for information carriers according to the invention consists in that the surface area of the opaque, non-reflective layer corresponds essentially to the surface area of the side of the carrier to be scanned by the laser beam. However, it is at least 11.9 cm. The surface area of the inner hole is exactly 1.5 cm.

A further preferred embodiment of the accessory for information carriers according to the invention is characterized in that the light-impermeable, non-reflective layer consists of a special white plastic.

The invention is explained in more detail below using an example and with reference to the accompanying drawing. The figure shows a perspective exploded view of an information carrier that can be scanned by means of an optoelectronic scanning system and that can be a compact disc or a digital versatile disc.

The accessory for information carriers according to the invention has a smooth side and a rougher side. To benefit from the greatest sound improvement, the rougher side of the accessory should be placed on the label. The amount of light shining through the partially transparent label is guided back for information evaluation in a finely differentiated manner by the special surface of the White Mirror No. 1. Light reflections that are difficult to evaluate are thus reduced to a minimum.

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Claims (3)

1. A white opaque film (White-Mirror No. 1) that has a smooth and a rough side. The smooth side has a roughness of approximately 4 to 7 µm. The rough side, which lies on the label, has a roughness of approximately 13 to 16.5 µm. The optimum thickness is 250 µm.
The accessory additionally stabilizes the information carrier to be played, which results in more precise scanning of the data to be read.
Characterized in that an opaque layer (film) ( 3 ) is arranged on the carrier ( 1 ) and the print ( 2 ). (It is placed loosely) 2. Accessory according to claim 1, characterized in that the surface area of the opaque, non-reflective layer ( 3 ) corresponds to the surface area of the side of the carrier ( 1 ) to be scanned by the laser beam. However, it is at least 11.9 cm. 3. Information carrier according to claim 1 or 2, characterized in that the opaque, non-reflective layer ( 3 ) is made of white plastic.