JPH06338009A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide a magnetic recording/reproducing device whose overwrite performance of an auxiliary track and the erase rate are improved, with hardly increasing the burden of a power source. CONSTITUTION:Recording amplifiers 25-28 are successively selected by a shift register 33, then the recording is performed through recording heads 21-24 connected to each recording amplifier. By a time constant circuit 35, the pulse width of one clock portion outputted from the shift register 33 is switched over to the pulse width of 2-clock or 3-clock by the control of a terminal 36. As the result, the recording strength recorded by a recording head for the auxiliary track is increased than the case for other tracks, or the recording of a specific recording signal is strengthened, therefore, the overwrite performance of the auxiliary track or the erase rate is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention distributes a digital signal to a plurality of tracks on a magnetic tape for recording, and
The present invention relates to a magnetic recording / reproducing apparatus having a dedicated track for recording time, music head information and the like.

[0002]

2. Description of the Related Art In a stereo audio digital magnetic recording / reproducing apparatus using a fixed head as represented by a DCC (Digital Compact Cassette), generally, recording is performed by distributing the recording on a magnetic tape in a plurality of tracks in view of recording density. It Further, in addition to the audio signal track group, an auxiliary track for recording, for example, time information, a start marker indicating the beginning of a song, etc. is provided.

Generally, when recording is performed on these track groups, so-called pulse train current recording is performed in which each track is sequentially recorded in time division. Hereinafter, an example of a conventional magnetic recording / reproducing apparatus will be described with reference to the drawings.

FIG. 5 is a block diagram of a conventional magnetic recording / reproducing apparatus. In FIG. 5, recording heads 1, 2, 3, and 4 show a part of heads of a recording head group consisting of n + 1 units formed in the same chip. Of these, the recording heads 1, 2, 3 record digital audio signals on the 1st, 2nd, and nth tracks, respectively, and record on auxiliary tracks for recording time information, start markers indicating the beginning of music, and the like. The heads 4 are respectively arranged so as to perform recording.

The recording amplifiers 5, 6, 7, and 8 are connected so as to drive the recording heads 1, 2, 3, and 4 of the recording amplifier group consisting of n + 1. Each recording amplifier group has an output control terminal, and each recording amplifier group drives a corresponding recording head group only when an H level signal is input to these output control terminals. .

A clock is input to the terminal 9. Terminal 1
0 is connected to each input terminal of the recording amplifiers 5, 6, 7, and 8, and a digital signal to be recorded is input to the terminal 10 in synchronization with the rising edge of the clock. In addition,
The digital signal input from the terminal 10 constitutes one block with n + 1 bits, and each block has 1, 2,
..., n + 1th bit is 1, 2, ..., n + 1
It shall be configured to be recorded on the second track.

The terminal 11 is supplied with a synchronizing signal in which an H level signal appears for one bit length at the switching portion of each block of the digital signal. The value of the terminal 11 shifts every clock in synchronization with the rising edge of the clock input to the terminal 9, and the output terminals Q1 and Q of the shift register 12
Output to 2, Qn, ..., Qn + 1. Shift register 1
The output terminals Q1, Q2, Qn, ..., Qn + 1 of 2 are connected to the output control terminals of the recording amplifiers 5, 6, 7, and 8, respectively. Note that the configuration related to the tracks other than the above is the same as the above configuration, and is therefore omitted in the drawings.

The operation of the conventional magnetic reproducing apparatus configured as described above will be described below. FIG. 6 is a diagram for explaining the operation of a part of FIG. 5, and the waveforms a, b, c, d, e, f, and g each show an example of the waveform of the same code point in FIG. . Also, at time t1,
, tn, tn + 1 represent the generation sections of the bits D1, D2, ..., Dn, Dn + 1 of the digital signal waveform c, respectively.

The synchronizing signal (waveform b) input from the input terminal 11 is sequentially shifted by the shift register 12 in synchronization with the rising edge of the clock (waveform a) input from the terminal 9, and the output terminals Q1, Q2, ... ., Qn, Qn + 1 have time t1, respectively, as shown in waveforms d, e, f, g.
In the t2, ..., Tn, tn + 1 sections, an H level signal is output for each 1-bit length. Therefore, the recording amplifiers 5, 6, 7 and 8 drive the recording heads 1, 2, 3 and 4 in the intervals t1, t2, tn and tn + 1, respectively.

Here, during the time periods t1, t2, tn, tn + 1, the bits D1, D2, Dn, Dn + 1 of the digital signal (waveform c) are input to the recording amplifiers 5, 6, 7, 8 respectively. Therefore, the recording currents corresponding to the bits D1, D2, Dn, and Dn + 1 respectively flow through the recording heads 1, 2, 3, and 4 for one bit length.

Similarly, since the signals are repeatedly input from the terminals 9, 10 and 11 for each block, the above-mentioned operations are also repeated.

As a result, all magnetic heads have a predetermined value of 1.
This is so-called pulse train current recording in which the recording current is supplied only for bits. It is generally said that the magnetic tape is magnetized continuously if the pulse train current interval is appropriately selected.

[0013]

Generally, the above-mentioned magnetic recording / reproducing apparatus does not have an erasing head. Therefore, when new recording is performed on a recorded magnetic tape, the recording head performs overwriting.

However, since the auxiliary track on which the recording head 4 performs recording has a low recording density and a long recording wavelength, the overwrite characteristic may be inferior to that of the other tracks.
In this case, there is a risk that the error rate after overwriting will become worse and the time information will not be read correctly. In order to solve this problem, it is effective to strengthen the recording, and conventionally, the overwrite characteristic has been improved by slightly increasing the recording current of the auxiliary track.

On the other hand, a method of searching the beginning of a piece of music in a fast-forward rewinding state is practically used in DCC, for example, by recording an auxiliary track of a magnetic tape intermittently, and depending on the shape of a reproduction envelope when the portion is reproduced. Has been converted. In this case, it is necessary to intermittently erase the old recording portion of the auxiliary track. As described above, since there is no erase head, a method of supplying a high frequency digital signal to the recording head 4 to erase the auxiliary track is adopted.

However, as described above, since the auxiliary track has a long recording wavelength, the erasing rate is likely to be insufficient when overwriting at a high frequency, and erroneous detection may occur during high-speed retrieval of the beginning of a song. In order to solve this problem, the erasing rate has conventionally been improved by further increasing the erasing current of the auxiliary track.

As a result, in order to improve the overwrite characteristic or the erasing rate of the auxiliary track, it is necessary to prepare the recording current in three stages depending on the track / recording signal content, and the power supply voltage must be increased only for the auxiliary track. There was a problem of not becoming.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a magnetic recording / reproducing apparatus in which the overwrite characteristic and the erasing rate of the auxiliary track are improved without increasing the burden on the power source. To do.

[0019]

In order to achieve the above object, a magnetic recording / reproducing apparatus of the present invention comprises a plurality of first magnetic heads for dividing a digital signal into a plurality of tracks and recording them on a magnetic tape. A magnetic head group including one or a plurality of second magnetic heads, a selection unit that sequentially switches the magnetic heads of the magnetic head group and selects only a first time width, and the selection unit selected by the selection unit. A first recording circuit for supplying the digital signal to the first magnetic head for the first time width and the first recording circuit for supplying the digital signal to the second magnetic head selected by the selecting means. A time constant circuit for extending the time width to a second time width; and a second recording circuit for supplying the extended digital signal to the second magnetic head according to the output of the time constant circuit. It is intended.

Further, the time constant circuit is provided with a switching means for selectively extending the first or second time width for supplying a digital signal to the second magnetic head to the third time width. is doing.

[0021]

According to the present invention, in the above structure, the pulse width of the pulse train current supplied to the second magnetic head is widened to the second time width to record the track recorded by the second magnetic head. Can be enhanced and the overwrite characteristics can be improved.

Further, by selectively extending the output of the time constant circuit to the third time width, the pulse width of the pulse train current supplied to the second magnetic head is expanded to the third time width. , The specific signal of the track recorded by the second magnetic head can be selectively strengthened to improve the overwrite characteristic by the specific signal.

[0023]

Embodiments of the magnetic recording / reproducing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing the structure of a magnetic recording / reproducing apparatus according to the first embodiment of the present invention. In FIG. 1, print heads 21, 22, 23, and 24 represent a part of heads of a print head group consisting of n + 1 pieces formed in the same chip. Of these, the recording heads 21, 22, 23
Records digital audio signals on the 1st, 2nd, and nth tracks, respectively. For example, the recording head 24 records on auxiliary tracks for recording time information, start markers indicating the beginning of music, and the like. It is arranged.

The recording amplifiers 25, 26, 27 and 28 are n +
Of the recording amplifier group consisting of one recording head 21, 21
2, 23, and 24 are connected so as to drive them, respectively. Each recording amplifier group has an output control terminal, and each recording amplifier group drives a corresponding recording head group only when an H level signal is input to these output control terminals. .

A clock is input to the terminal 29. The terminal 30 is connected to the input terminals of the recording amplifiers 25, 26 and 27 and also connected to the input terminals of the recording amplifier 28 via the latch 31. A digital signal to be recorded is input to the terminal 30 in synchronization with the rising edge of the clock. Here, the digital signal input from the terminal 30 constitutes one block with n + 3 bits, and the 1,2, ..., N + 1-th bit of each block is 1, 2, ..., N + 1-th track. Be configured to be recorded in. In addition, one block is set to have a period of an even fraction of the shortest wavelength to be recorded on the magnetic tape.

The terminal 32 is supplied with a synchronizing signal in which an H level signal appears for one bit length at the switching portion of each block of the digital signal. In synchronization with the rising edge of the clock input to the terminal 29, the value of the terminal 32 shifts every clock to output the output terminal Q1 of the shift register 33,
Output to Q2, ..., Qn, Qn + 1. The output terminals Q1, Q2, Qn of the shift register 33 are connected to the output control terminals of the recording amplifiers 25, 26, 27, respectively, and the output terminal Qn + 1 controls the output of the recording amplifier 28 via the time constant circuit 34. It is connected to the terminal and the control terminal of the latch 31.

The time constant circuit 34 is constructed to extend the 1-bit length H level signal input from the output terminal Qn + 1 of the shift register 33 to the 2-bit length and output it.
The time constant circuit 34 is simply composed of flip-flops and gates, and detailed description thereof will be omitted. The latch 31 latches and outputs the input signal in synchronization with the rising edge of the output of the time constant circuit 34.

It is assumed that the gap length of the recording head is appropriately set in advance so that a gap does not occur in the magnetization on the magnetic tape recorded by the pulse train current.

The operation of the magnetic recording / reproducing apparatus of the first embodiment of the present invention constructed as above will be described below. FIG. 2 shows an operation explanatory diagram for a part of FIG. 1, and shows waveforms h, i, j, k, l, m,
p, q, r, and s respectively show an example of the waveform of the same code point in FIG. Time t1, t2, ..., tn,
tn + 1 is the bit D of the digital signal (waveform j).
.., Dn, Dn + 1 are generated.

Clock input from terminal 29 (waveform h)
The synchronizing signal (waveform i) input from the input terminal 32 is sequentially shifted by the shift register 33 in synchronism with the rising edge of, and the output terminals Q1, Q2, and Qn have the waveform k,
As shown by l and m, the times t1, t2, ...
An H level signal is output for each 1-bit length in the n section. Therefore, the recording amplifiers 25, 26, and 27 are respectively provided in the recording heads 21 and 26 during the time periods t1, t2, and tn.
22 and 23 are driven.

Here, since the bits D1, D2 and Dn of the digital signal (waveform j) are input to the recording amplifiers 25, 26 and 27 in the sections of time t1, t2 and tn, respectively, the recording heads 21 and 22. , 23 has bit D
The recording currents corresponding to 1, D2, and Dn respectively flow by 1 bit length.

By the way, at the output terminal Qn + 1, as shown by the waveform p, an H level signal appears for one bit length in the time period tn + 1 and is supplied to the time constant circuit 34. The output of the time constant circuit 34 is the time tn + 1, tn as shown in the waveform q.
A 2-bit long H level signal appears in the +2 section. Therefore, the recording amplifier 28 drives the recording head 24 in the sections tn + 1 and tn + 2.

On the other hand, in the time period tn + 1, the latch 31 receives the digital signal bit Dn + 1 from the terminal 30 as shown by the waveform j, and the time constant circuit 34 as the H level signal as shown by the waveform q. To enter. Here, when the waveform q passes through the shift register 33 and the time constant circuit 34, a delay of, for example, several tens of nanoseconds occurs. Time tn +
When the H level signal of the waveform q is input to the control terminal of the latch 31 in one section, the bit Dn + 1 of the digital signal shown in the waveform j is already input to the latch 31. Therefore, the latch 31 latches the digital signal Dn + 1 as shown by the waveform r in the time period tn + 1.

Therefore, during the time periods tn + 1 and tn + 2, the recording amplifier 28 is driven and the recording current (waveform s) corresponding to the bit Dn + 1 flows through the recording head 24 over a 2-bit length.

Similarly, since the signals are repeatedly input from the terminals 29, 30, 32 for each block, the above-mentioned operations are also repeated.

As described above, a recording current having a wider pulse width than the other tracks flows through the auxiliary track. Generally, as the pulse width of the pulse train recording current is widened, stronger recording tends to be performed on the magnetic tape even with the same pulse crest value. Furthermore, the overwrite characteristic tends to be improved as the recording strength increases. Therefore, the overwrite characteristic of the auxiliary track having a long recording wavelength is improved.

As described above, according to this embodiment, the time tn +
Even if the recording current (waveform s) flows through the recording head 24 in the 1 and tn + 2 sections over a 2-bit length, it does not overlap with other tracks, so the maximum load current of the power supply does not increase. Further, since the set time of the time constant circuit 34 is synchronized with the clock, a time constant circuit that is not affected by temperature characteristics or element variations can be realized.

Next, a magnetic recording / reproducing apparatus according to a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a circuit diagram showing the configuration of a magnetic recording / reproducing apparatus according to the second embodiment of the present invention. In FIG. 3, recording heads 21, 22, 23, 24, recording amplifiers 25, 2
6, 27, 28, terminals 29, 30, 32, latch 31 and shift register 33 are completely the same in configuration, function, and mutual connection relationship with those of the same reference numerals in FIG. 1 in the first embodiment of the present invention. The description is omitted. Further, the clocks, digital signals, and synchronizing signals respectively input to the terminals 29, 30, 32 are the same as those of the same reference numerals in FIG. 1 in the first embodiment of the present invention, and therefore their explanations are omitted.

The time constant circuit 35 extends the 1-bit length H-level signal input from the output terminal Qn + 1 of the shift register 33 to 2-bit length when the terminal 36 is at L level, and the terminal 36 is at H level. In case of, it is extended to 3 bit length,
It is configured to output to the output control terminal of the recording amplifier 28 and the control terminal of the latch 31. The time constant circuit 35 is simply composed of flip-flops and gates, and detailed description thereof will be omitted.

The operation of the magnetic recording / reproducing apparatus of the second embodiment of the present invention constructed as above will be described below. FIG. 4 is a diagram for explaining the operation of a part of FIG. 3, showing waveforms h, i, j, p, v, w,
x and y each show an example of the waveform of the same code point in FIG. It is obvious that the waveforms of the code points k, l, m in FIG. 3 are equal to the waveforms of the same symbols in FIG. 2 in the first embodiment of the present invention, and the explanation thereof is omitted in FIG. There is. Time t1, t2, ..., tn, tn
+1 represents the generation section of the bits D1, D2, ..., Dn, Dn + 1 of the digital signal (waveform j) in the same block, and the time u1, u2 ,. Bit Z of digital signal (waveform j) in each next block
1, Z2, ..., Zn, Zn + 1 represents the generation section.

Clock input from terminal 29 (waveform h)
The synchronizing signal (waveform i) input from the input terminal 32 is sequentially shifted by the shift register 33 in synchronism with the rising edge of, and the output terminals Q1, Q2, and Qn have time t1, t2, ..., Tn sections, respectively. At, an H level signal is output for each 1 bit length. Therefore, the recording amplifiers 25, 26 and 27 drive the recording heads 21, 22 and 23 during the time periods t1, t2 and tn, respectively.

Here, since the bits D1, D2 and Dn of the digital signal (waveform j) are input to the recording amplifiers 25, 26 and 27 in the sections of time t1, t2 and tn, respectively, the recording heads 21 and 22. , 23 has bit D
The recording currents corresponding to 1, D2, and Dn respectively flow by 1 bit length. The same applies to the next block, and the recording head 2 is used in the time intervals u1, u2, and un.
Recording currents corresponding to the bits Z1, Z2, and Zn of the digital signal (waveform j) flow through the channels 1, 22 and 23 by 1 bit length, respectively.

By the way, it is assumed that the input signal of the terminal 36 is an L level signal in the first block and an H level signal in the next block, as shown by the waveform v. In this case, the output of the time constant circuit 35 is as shown in the waveform w,
2 bits long from time tn + 1 to tn + 2, time un +
A 3-bit long H level signal appears in the section from 1 to un + 3.

On the other hand, the latch 31 receives the bits Dn + 1 and Zn + 1 of the digital signal from the terminal 30 as shown in the waveform j in the intervals tn + 1 and un + 1, respectively, and the waveform w
As shown in, an H level signal is input from the time constant circuit 35. Here, when the waveform w passes through the shift register 33 and the time constant circuit 35, a delay of, for example, several tens of nanoseconds occurs. That is, when the H level signal of the waveform w is input to the control terminal of the latch 31 in the sections of time tn + 1 and un + 1, the bit Dn + of the digital signal shown in the waveform j is shown.
1 and Zn + 1 have already been input to the latch 31. Therefore, the latch 31 receives the digital signal Dn + 1 as shown by the waveform x in the time tn + 1 section and the digital signal Zn + in the time un + 1 section.
Latch 1 respectively.

Therefore, in the first block, the time tn +
In the section 1 and tn + 2, the recording amplifier 28 is driven and the recording current (waveform y) corresponding to the bit Dn + 1 flows through the recording head 24 over the length of 2 bits, and in the next block, the time un + 1, un + 2. , Un + 3, the recording amplifier 28 is driven and the recording current (waveform y) corresponding to the bit Zn + 1 flows through the recording head 24 over a 3-bit length.

Similarly, since the signals are repeatedly input from the terminals 29, 30, 32 for each block, the above-described operation is repeated, and the recording head 2
A pulse train current having a length of 2 bits when the terminal 36 is at the L level and a pulse train current having a length of 3 bits when the terminal 36 is at the H level are supplied to the circuit 4.

As described above, the recording current having a wider pulse width than that of the other tracks flows in the auxiliary track, and the recording current having a wider pulse width can be supplied by switching the input of the terminal 36. Generally, as the pulse width of the pulse train recording current is widened, stronger recording tends to be performed on the magnetic tape even with the same pulse crest value.

That is, by setting the terminal 36 to the H level to make the pulse width of the recording current of the short wavelength for erasing wider than that of other recording signals, the erasing rate of the already recorded portion of the long wavelength which is hard to be erased can be improved. .

As described above, according to this embodiment, the time un +
Even if the recording current (waveform y) flows through the recording head 24 over the length of 3 bits in the section 1 to un + 3, the current does not overlap with other tracks, so the maximum load current of the power supply does not increase.
Further, since the set time of the time constant circuit 35 is synchronized with the clock, a time constant circuit free from the influence of temperature characteristics and element variations can be realized.

[0052]

As described above, according to the present invention, the pulse width of the pulse train current supplied to the first magnetic head (first time width) is different from the pulse width of the pulse train current supplied to the second magnetic head. By extending the second time span,
The recording of the track recorded by the second magnetic head can be strengthened without increasing the load of the power source, the overwrite characteristic is improved, and the reliability of the device is improved.

Further, the present invention comprises a time constant circuit having a switching means for selectively extending the first or second time width for supplying the digital signal to the second magnetic head to the third time width. As a result, the specific signal of the track recorded by the second magnetic head can be selectively strengthened without increasing the load on the power source, so that the overwrite characteristic or the erasing rate by the specific signal is improved, Reliability is further improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a magnetic recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the circuit according to the first embodiment.

FIG. 3 is a circuit diagram showing a configuration of a magnetic recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 4 is a timing chart for explaining the operation of the circuit according to the second embodiment.

FIG. 5 is a circuit diagram showing a configuration of a conventional magnetic recording / reproducing apparatus.

FIG. 6 is a timing chart for explaining the operation of the circuit in the conventional example.

[Explanation of symbols]

 21, 22, 23, 24 recording head 25, 26, 27, 28 recording amplifier 29, 30, 32, 36 terminal 31 latch 33 shift register 34, 35 time constant circuit

Claims (2)

[Claims] 1. A magnetic head group comprising a plurality of first magnetic heads for dividing a digital signal into a plurality of tracks and recording the magnetic tape on a magnetic tape, and one or a plurality of second magnetic heads, The magnetic heads of the magnetic head group are sequentially switched to the first
Selecting means for selecting only the time width, a first recording circuit for supplying the digital signal to the first magnetic head selected by the selecting means for the first time width, and selecting by the selecting means. The first time width for supplying the digital signal to the second magnetic head
And a second recording circuit that supplies the extended digital signal to the second magnetic head according to the output of the time constant circuit. 2. The time constant circuit comprises switching means for selectively extending the first or second time width for supplying a digital signal to the second magnetic head to the third time width. The magnetic recording / reproducing apparatus described.