JPH022226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a method for recording index data relating to information at the beginning of information recorded on a magnetic tape of a tape recorder.

(b) Technical background Conventionally, when recording information with a tape recorder, for example, when recording music, index data such as the song number of the music is recorded at the beginning of the music, and the tape recorder records index data such as the song number of the music. In fast forward mode or rewind mode, index data is detected to control music searches and the like.

Recording of such index data is performed by the method shown in FIG. In FIG. 1, the index data consists of 4 bits, and when recording this index data, data signals D4 to _D4 corresponding to each bit of the index data are used.
_D1 , a start bit pulse _P1 provided before the data signal _D4 , and a stop bit pulse _P2 provided after the data signal _D1 . The information is recorded at the beginning and on a different track. Furthermore, in the pulse train shown in FIG.
Each pulse width, data signal width, and interval are set to be equal, and during recording, recording is performed in 50 ms. The index data in Figure 1 is "0001".
The data signals D ₄ , D ₃ , and D ₂ are at the "0" level as shown by the solid lines.

When detecting the pulse train shown in FIG. 1 in fast-forward mode, the pulse train shown in FIG. 2 is detected by the method shown in FIG. Near the end of winding in fast forward mode, the tape speed is about 20 times that of recording, so the pulse width and pulse interval are about 2.5 ms. When reading index data in this state, starting points T ₁ , T ₂ , T ₂ , T ₂ ,
By reading the signals at T ₃ and T ₄ ,
Index data can be read. In the example of FIG. 2, it can be read as "0001".

However, if there is an error in the base point setting or reading interval setting, the error will be accumulated at later reading times, resulting in a discrepancy with the data signal.
There is a risk of a reading error. Furthermore, at the beginning of winding in fast forward mode, the tape speed is approximately 10 times that of recording, and the interval between the pulse and data signal width is 5 ms, and the pulse train shown in Figure 2 is expanded twice in the direction of the arrow. will be done. Therefore, in this case, reading is impossible with the reading interval shown in FIG. 2, and it is necessary to reset the reference point and reading interval.

(C) Disclosure of the Invention The present invention has been made in view of the above-mentioned points, and it provides a synchronous bit pulse before each data signal created based on the content of each bit of index data consisting of a plurality of bits. To provide an index data recording method for a tape recorder which can prevent index data reading errors in fast forward mode by creating a pulse train and recording this pulse train at the beginning of recorded information.

(d) Embodiment FIG. 3 is a waveform diagram showing an embodiment of the present invention.
In the figure, pulses P ₁ to _{P 9} are cue signals,
In order to prevent the tape recorder from malfunctioning due to noise or the like, a pulse train based on index data is provided before recording. When detecting in the fast forward mode, when nine consecutive pulses are detected, this is recognized as a cue signal, and index data is read from the pulse train that arrives thereafter. In this embodiment, the index data consists of 4 bits, and the contents of each bit of the index data are the data signals D 4 , _{4 and 4} , respectively.
Created as D ₃ , D ₂ , D ₁ . That is, when the bit is "0", the data signal does not exist as a pulse, and when the bit is "1", it becomes a pulse. When the data signals D ₄ to _{D 1} are shown by solid lines in FIG. 3, the index data has the content of "0001". Index data to data signal D ₄
When converting into a pulse train of _D1 to D1 and recording, synchronization bit pulses _S1 to _S4 are always provided before each data signal _D4 to _D1 . A pulse train formed by the synchronization bit pulses S ₁ to S ₄ and data signals D ₄ to _{D 1} is provided after the cue signal pulse P ₉ at an interval of one pulse, and these pulse trains are recorded. information is recorded on a different track.

When reading index data in fast forward mode, each synchronous bit pulse S ₁ to S ₄ is detected, the falling edge of each synchronous bit pulse S ₁ to S ₄ is used as a reference point, and a predetermined time t _C has elapsed from that reference point. At that point, read the data. t _C is set to always exist between t ₁ and t ₂ in fast forward mode. Therefore, in principle, the data signals _D4 to _D1 are generated from the falling edge of the synchronous bit pulses _S1 to _S4 .
The relationship between the time t ₁ until the start of the data signal D ₄ and the time t ₂ until the end of the data signal D 4 to D ₁ is set at the time of pulse train creation so that it is equal to the ratio of the minimum speed to the maximum speed of the tape in fast forward mode. Set. For example, in a normal tape recorder, if the tape speed at the beginning of winding in fast forward mode is 1, the tape speed at the end of winding is 2. Therefore,
In this case, _the synchronization bit pulses S ₁ to _{S 4} and the data signals _{D 4} to
Create D ₁ and record it on tape. At the time of recording,
In the case of recording at t ₁ =50 ms and t ₂ =100 ms, the relationship with the data reading time t _C in fast forward mode is shown in FIGS. 4a and 4b.

FIG. 4a shows the sync bit pulse Sn and data signal Dn near the end of the winding in fast-forward mode. Near the end of the tape, the tape speed is 20 times that of recording, so t ₁ is 2.5 ms and t ₂ is 5 ms.
On the other hand, FIG. 4b shows the synchronization bit pulse Sn and data signal Dn at the beginning of winding in fast forward mode. At the beginning of winding, the tape speed is 10 times that of recording, so t ₁
is 5ms, and _t2 is 10ms. Therefore, if the data reading time t _C is set to 5 ms, data will be read at the end of the data signal Dn near the end of the tape, and data will be read at the beginning of the data signal Dn at the beginning of the tape. Even if the speed changes, there will always be a data reading point within the width of the data signal. Also,
As is clear from Figure 4 a and b, at the time of recording, t ₁
50 ms and t ₂ 100 ms, that is, 2t ₁ t ₂ , the reading time t _C is definitely within the data signal. Since the falling edge of each synchronizing bit pulse S ₁ to _{S 4} is used as the base point, there is no need to accumulate errors.

(e) Effects As described above, according to the present invention, before the data signal corresponding to each bit of index data,
By providing a synchronizing bit pulse and recording the pulse train formed by this at the beginning of the recorded information, the synchronizing bit pulse can be detected in fast forward mode, and data can be read using this as a reference point. Therefore, data reading errors can be prevented, and the tape recorder can be controlled without malfunction.

[Brief explanation of drawings]

Fig. 1 is a pulse waveform diagram showing a conventional example, Fig. 2 is a diagram showing a conventional method of detecting pulse waveforms, and Fig. 3 is a diagram showing a conventional pulse waveform detection method.
The figure is a pulse waveform diagram showing an embodiment of the present invention, and FIGS. 4a and 4b are diagrams showing detection pulses at the end and start of tape winding in fast forward mode.

Claims (1)

[Claims] 1. In a method of recording index data consisting of a plurality of bits related to the information at the beginning of the information to be recorded, a data signal corresponding to each bit of the index data is created, and each of the data signals is A method for recording index data in a tape recorder, characterized in that a pulse train formed by arranging a synchronization bit pulse beforehand is recorded at the beginning of the information to be recorded.