HK111796A - Reproduction device - Google Patents

Description

The invention relates to a reproduction device which reads data from a rotating plate at a constant speed.

A well-known such player is the CD player, which plays a compact disc with a constant speed. In English, such a system is called a constant linear velocity system. The common abbreviation is CLV system. In contrast, in an analogue record player, which is a constant angular system, the angular speed of the disc is constant.

The speed of the recording of a compact disc in a CD player must therefore correspond to its recording speed. If the compact disc was recorded at a speed of, for example, 1.2 m/s, it must also be played at the same speed of 1.2 m/s. However, where the recording speed may be between 1.2 m/s and 1.4 m/s, each compact disc has its own record-specific record-speed, e.g. 1.2 m/s or 1.3 m/s or 1.4 m/s.

For example, when a one-hour piece of music is recorded on a compact disc, the pit length is greater at a higher recording speed than at a lower recording speed.

The scan speed is derived from the HFS signal in a CD player, which scans a beam of light from the compact disc. In a decoder, the sound signal and a synchronous signal are obtained from the HF signal, which regulates the disc drive to the correct speed. Therefore, in a CD player, each compact disc is rotated with the disc-specific scan speed. The bitrate of the read out bits is kept constant.

However, in order to be able to find a desired place on a record, e.g. a piece of music, and to calculate the number of tracks to be skipped, it is not enough to know that the scan speed is between 1.2 m/s and 1.4 m/s. The more accurately the scan speed for a particular record is known, the more accurately the number of tracks can be calculated.

EP-PS 0 214 256 is known to have a CD player which determines the plate-specific scan speed by deriving the plate speed from the filtered frequency of a focus error signal.

A disadvantage of the well-known CD players which measure the speed of the disc is that it must be determined for each disc inserted, but this process takes time and the operator wants the disc to be played as soon as possible after inserting.

The purpose of the invention is therefore to reduce the time between inserting and playing the disc in a CD player.

The invention solves this problem by providing a memory in the reproduction device to store the specific scan speed of several discs.

The measure to store the plate-specific scan speed for several discs eliminates the need to retest the plate-specific scan speed when a disc already played is inserted back into the CD player for replay, thus significantly reducing the time between inserting and playing the disc.

The individual plates can be identified, for example, by the coded catalogue numbers contained in the subcode of the plate or by individual characteristics of the subcode.

In a magazine player, it is possible to clearly assign the plates to a magazine and to store the plate-specific scan speed in order by plate and magazine.

The figure shows a first example of the invention, which is explained below.

The compact disc CD is scanned by an optical scan device A, which delivers data to a data processing circuit D. The data processing circuit D is connected to the input of an identification circuit I, which evaluates the subcode of the inserted disc CD. In a comparison device V, it is checked whether the received subcode already has the plate-specific scan speed stored in a memory S. If yes, the stored plate-specific scan speed is taken from the memory S SV and made available to the servo circuits of the CD player. If the plate inserted has not yet been stored, the plate-specific scan speed of the inserted disc is first determined, e.g. in accordance with the EP-2254 procedure described in SPS 0 and described in the following table.

In another embodiment of the invention, the operator is given the option of deleting the data in memory S.

The invention is suitable for playback devices, which are known as CLV systems because they scan a disc at a constant speed, such as CDS players, video disc players, DRAW disc players and magneto-optical recording and playback devices.

Claims (5)

1. Reproduction device which reads data from a rotating disk (CD) at constant linear velocity and is equipped with means in order to determine the track-scanning speed specific to the disk, characterized in that a memory (S) is provided in the reproduction device in order to be able to store the specific track-scanning speed for several disks.
2. Reproduction device according to claim 1, characterized in that the user has the option of deleting the contents of the memory (S).
3. Reproduction device according to claim 1 or 2, characterized in that it is a CD player.
4. Reproduction device according to claim 1, 2 or 3, characterized in that it is a cartridge device in which the track-scanning speed specific to a disk can be stored in the memory (S) in order according to disks and cartridges.
5. Reproduction device according to claim 1, 2, 3 or 4, characterized in that a scanning device (A), which reads the data from a disk (CD), is connected to a data-processing circuit (D), the output of which is connected to the input of an identification circuit (I) for identifying the disk (CD), that the output of the identification circuit (I) is connected to a comparison circuit (V) which is connected to the memory (S), that the identification circuit (I) is also connected to a device for determining the track -scanning speed specific to the disk, and that said device for determining the track-scanning speed specific to the disk is also connected to the memory (S).