Method and device for monitoring recorded data.

p0001The present invention relates to a method and apparatus for recording data on a rewritable disk.

p0002It is generally known to store data on a rewritable data carrier and read out from this. Such a re-recordable disk, for example, a magnetic tape, a recordable optical disc such as a magneto-optical disc to be (MOD), a mini disc (MD) or the like. The relevant data, the audio information, video information and / or data for electronic data processing may contain, can be impressed on the disk in digital or analog manner.

p0003In the cases in which the data carrier as a tape, such as is provided as a magnetic tape, is formed, the data is recorded in tracks whose position is predetermined by the position of a write head. The data is read by a read head, which can be mechanically rigidly connected to the stylus.

p0004It has been found that disks that were recorded some time ago from a data recording system, as an audio, video or data recorder, have a loss of information. This is partly due to physical effects under the influence of heat, for example in transportable mode or inside a motor vehicle caused or by a relative displacement of the read head relative to the location of the recorded tracks.

p0005It is the object of the present invention to detect a possible data loss that can occur due to physical effects in a storage medium, mechanical tolerances or the like within wide limits and, if necessary, to reduce.

p0006This object is achieved by a method according to the main claim and by a device according to the first product claim.

p0007According to the invention, a data recording device comprising means for writing data of the mentioned type, also briefly referred to below as write head, called a corresponding data carrier and a respective means for reading these data, including read head, as described below, changed.

p0008The level of the read out by the read head the data is compared with a setpoint value. This may be a measure for a minimum average level of the readout data, a minimum maximum level and / or the like. Falls below the corresponding level of the read data to said target value, so it is assumed that the threat of data loss and generates an appropriate warning signal.

p0009In a preferred further development of the warning signal is used to initiate a so-called refresh mode. In this mode, a signal containing the data to be processed is read from the Datent lively by the read head and rewritten by the write head on the disk. The read or aufzuschreibenden signals are amplified such that at a later reading of the "refreshed" signals at a level above the required target level is to be expected. A comparison of the corresponding gain factor can be adjusted by a test run, which comprises predetermined portions of the disk.

p0010If the read or write head or both heads of unwanted reasons are out of adjustment, it is possible that they describe or read different tracks. This can lead to malfunction of the method described above. Such misalignment of the heads with each other can be detected by a test mode. In this test mode of the write head a predetermined signal, preferably having a known level, written and read by the read head. If the result is a deviation between the set and written to the read level, a corresponding error signal is generated. This can serve to indicate this deviation a user optically and / or acoustically or in another example. Further, the error signal can also be used for automatic position correction of at least one of the two heads.

p0011In a tape recorder, the refresh operation is advantageously carried out by the end of the strip towards its beginning. This is particularly useful for devices with a so-called tape monitoring on in which, seen in the strip running direction, the read head is disposed behind the stylus and with only a slight delay in normal operation reads the written data to the control. Since reading out of data and then a corresponding writing of this data is first necessary for the refresh mode, the data band, based on the read / write heads, running in reverse direction compared to the normal operation should be. It returns the same data tracks are to be regarded in two modes, ie in each case those for which one or ones of the other tape direction.

p0012To avoid a change in the strip running direction, which seems also justified in terms of the technical and financial efforts, the use of additional read and write heads to offers that may be assigned locally to the corresponding read and write heads, that each reading head is a recording head, each Stylus assigned a reading head. When using two combined read / write heads, ie twice a combined read / write head, the effort is reduced even further. The heads can be exchanged electronically or mechanically by suitable switching means. The stylus can be used as a reading and the reading head used for confidence monitoring as stylus. Thus a movement direction change of the strip or a physical exchange of the heads is omitted.

p0013Although intended for a recording Vormagnetischerung can also cause a deletion, an erasing head for at least is in one embodiment between the two read / write heads at least one track to be cleared, or a so-called Vollöschkopf mounted, the magnetic tape before recording the refreshed data in at least a track or deletes the entire width. The clearing process is important in the case of recorded analog data, as may the refreshed data can be greatly affected by a non-negligible remanence of the "old" data in their quality.

p0014Further features, details and advantages of the invention will be described in the following embodiments with the aid of the figures. It shows

p00151 shows a preferred embodiment.

p0016Before the embodiments are explained in detail, the description, it should be noted that the may be combined in the figures for better understanding of the invention, steps shown separately also in other stages of an integrated circuit, hybrid circuit, or the like. At least one of these steps can also be implemented by a microcomputer or by a suitable for its control program.

p0017Medium contained the following in a stage may also be performed separately.

p0018Figure 1 shows a preferred embodiment as part of a tape recorder for digital data recording, for example, a Digital Compact Cassette is (DCC) executed. Only those agents have been shown, which serve to illustrate the invention and the embodiment. Other means, such as those for the tape drive, have been omitted for the sake of clarity.

p0019In normal operation (Nb), a magnetic tape 10 is moved from left to right. In this case, data packets 1, ..., 4 is read out by a read head 11 and amplified by an amplifier 12th A first amplified by this amplifier 12 signal is sent to means, which are indicated by a block 13 and process the data read from the tape 10 and provide data corresponding to audio and / or video information to a user, the.

p0020The data packets 1, ..., 4 may have been written during the same or during any previous belt travel from a write head 14 on the tape 10th The head 14 receives appropriate signals from a signal source 15 which may be for example a tuner, an external audio and / or video source or the like. The signals supplied by the signal source 15 are, if necessary, digitized by a conditioning stage 16, and guided to a prescribed level to the recording head fourteenth

p0021The data packets 1, ..., 4 may also have been a different operating according to similar procedures recording unit written on the tape 10th

p0022Further, a control unit 17 is also provided to which a second signal of the amplifier 12 is supplied. The control unit 17 compares a mean level value of this second signal to a predetermined setpoint. If the level value less than the setpoint, then the control unit 17 generates a corresponding warning signal to an operator stage 18, the acoustically to the user or further means and / or optically signaled or otherwise a corresponding level state. The user is thus prompted to initiate a refresh mode on the stage 18 or to allow at least.

p0023After the user has made a corresponding input, the belt 10 is wound in this embodiment, to the end, that is to say as far as possible to the right (Nb). Subsequently, the tape for performing the refresh mode in the opposite direction (Am) is moved at a predetermined speed. The recorded data are first moved past the read head 11 and the controller 17 contains a corresponding signal from the amplifier 12. The control unit 17 checks this signal in level and amplifies it so far until a predetermined level is reached. With this level the signals are applied to the stage 16, which drives the write head 14 accordingly. The control unit 17 can check the 12 received by the stage digital signals to errors and correct them if necessary accordingly.

p0024By the refresh mode is carried out on the belt 10, a shift of the data packets 1, ... 4, the tape end, and namely by the distance corresponding to the distance between the read head 11 and write head 14. As a result, if the tape 10 already to was described at the end to the loss of data. However, this is comparatively small, since the distance between the heads a maximum in the range of a few centimeters is, during the entire strip length typically amounts to a few hundred meters. In order for a loss of data, which may be equivalent to a loss of music enjoyment or the like, but may also be a loss of control data, for example, for a data processing system mean, does not lead to unpleasant surprises is, in the described embodiment, the release on the stage 18 interposed.

p0025In another embodiment, can be caused by the warning signal, a check is determined by whether the tape is recorded 10 to the end or if there is enough space for refreshing is available. The corresponding result can be displayed to the user or automatically lead to the refresh mode.

p0026Further, the non-recorded tape end can be used to check the relative position between the two heads 11 and 14, for example, by the controller 17, the stage 16 drives with predetermined signals, which lead to a corresponding record. The appropriate test signals can be varied in frequency and / or level. In addition, where appropriate, be corrected, a bias of the tape 10th

p0027The test signals can also existing data 1, ..., 4, are used, which are read out, processed and re-stamped in accordance with the band 10th By operating in Nb-direction these refreshed data can then be checked.

p0028In a further refinement of the embodiment described, a memory is provided in which the output from the stage 12 to the control device 17 signals are latched. By reading and properly time-controlled routing over the step 16 and read in via stylus 14, the data packets 1, ..., 4, in their rejuvenated form is written to the same location of the belt 10, where they were present before. This is a shifting of the data packets to the back end of the tape, and thus a loss of data is avoided. In this configuration, the refresh mode (Am) carried out both in the one direction of the tape (Nb) and in the other tape direction.

p0029In a further embodiment, a tape device is used with an analog signal recording. In this case, analog signals can be refreshed by the controller 17th Preferred is a digitization of analog signals played backwards for caching. The subsequent reconverting to analog signals and to transfer to the belt 10 prevents rejuvenated in shape or reduced data loss.

p0030In a further embodiment of the recording apparatus for discs, such as MOD or MD is suitable. Even in these cases can threaten a loss of data, for example by radiation influences such as thermal, electromagnetic or other radiation or waves. The comparison to a desired level and optionally subsequent refresher and test mode is performed similarly to the embodiment of FIG. 1