JPH065594B2 - Digital magnetic recording / reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a digital magnetic recording / reproducing apparatus, and more particularly to a digital magnetic recording / reproducing apparatus for converting an analog signal into a digital signal and recording / reproducing it on a magnetic tape.

[Prior Art] A rotary head type digital audio tape recorder (hereinafter referred to as DAT) will be described below as an example.

FIG. 7 is a diagram showing an arrangement of a drum, a head and a magnetic tape of a conventional digital magnetic recording / reproducing apparatus. In the figure, A magnetic head 502A and B magnetic head 502
B's are mounted on the drum 501 at an angle of 180 ° to each other. The magnetic tape 504 is 2000 r.p.m. p. m. Of two magnetic heads 502A, which have different azimuth angles and are wound around a drum 501 rotating at
A magnetic tape 504 as shown in FIG.
Recording is performed so that tracks are sequentially formed obliquely with respect to the longitudinal direction of the.

FIG. 8 is a diagram showing a magnetization pattern when a signal is recorded on a magnetic tape in a conventional digital magnetic recording / reproducing apparatus. In the figure, an arrow 506 is a running direction of the magnetic tape 504, and an arrow 507 is a magnetic head scanning direction. The magnetization patterns 505A and 505B are A magnetic heads 502A and 502B.
Recording is performed by the magnetic head 502B.

FIG. 9 is a diagram showing signals recorded on one track of the magnetization pattern shown in FIG. In the figure, a signal recorded on one track is composed of 196 blocks, and areas 510 and 516 for recording a constant frequency in a margin portion each of which includes 11 blocks and an area 511 for recording additional information each including 10 blocks. 515, areas 512 and 514 for recording servo signals each consisting of 13 blocks, a signal obtained by converting an audio signal consisting of 128 blocks into a digital signal (hereinafter referred to as an audio symbol), and a redundant signal for error correction. PC to record (hereinafter referred to as check symbol)
It is composed of an M region 513.

FIG. 10 is a diagram showing the structure of one block recorded in the PCM area 513. In the figure, one block consists of 36 symbols (1 symbol = 8-bit digital data), an S area 520 in which a block sync signal consisting of 1 symbol is recorded, and control information such as emphasis presence / absence consisting of 3 symbols. A recorded ID area 521 and a PCM area 5 in which an audio symbol consisting of 32 symbols and a check symbol are recorded
22 and 22.

FIG. 11 shows A magnetic head 502A and B magnetic head 502.
It is a figure which shows the signal waveform recorded and reproduced by B. In the figure, the waveform 523A is recorded and reproduced by the A magnetic head 502A, and the waveform 523B is recorded and reproduced by the B magnetic head 502B. Also, the signal for 196 blocks is 90 ° of the drum.
Recorded or played during the rotation period (= 7.5 msec),
A signalless period occurs in the next 90 ° rotation period. The error-free coding or decoding is performed using this no-signal period.

FIG. 12 is a block diagram showing a conventional DAT recording / reproducing signal processing apparatus. In the figure, the upper part from the center of the drawing shows the signal processing at the time of recording, and the lower part shows the signal processing at the time of reproduction. Two-channel analog signals are input to the terminals 601a and 601b, a recording signal is output to the terminal 620, a reproduction signal is input to the terminal 610, and a terminal 619 is input.
Two-channel reproduced analog signals are output to a and 619b.

FIG. 13 is a diagram showing a time chart for the signal processing operation at the time of recording in FIG. In the figure, the reference signal H indicates the start of recording, and one rotation of the drum (30
It is generated every msec) by the clock generation circuit 618 or the servo circuit that controls the drum.

FIG. 14 is a diagram showing a configuration of a conventional DAT clock generation circuit 618. In the figure, a terminal 701 is a terminal for inputting a channel clock (9.408 MHz), a terminal 707 is a terminal for inputting a reference signal H, and a terminal 708 is a terminal for outputting timing.

The conventional DAT is configured as described above, and in FIG. 12, two-channel analog signals input from terminals 601a and 601b are low-pass filters 602 and A.
It is converted into a digital signal through the D converter 603 and temporarily stored in the memory 604. The audio symbol generated in one rotation period of the drum stored in the memory 604 is
The data is divided into two data groups recorded by the A magnetic head 502A and the B magnetic head 502B, and the error correction of the encoder 606 is encoded in units of the audio symbols recorded on one track, and the data is transmitted to the modulator 607 at the next stage. Sent. The modulator 607 performs 8-bit-10-bit modulation for converting the data from the memory 604 and the data from the control information / additional information generation circuit 621 into 10 bits in units of symbols (8 bits). It is output to the signal synthesis circuit 608 of the stage. In this signal synthesizing circuit 608, a block synchronizing signal, a margin area signal and a servo signal are added and output as a signal of 196 blocks shown in FIG.
Output from the terminal 620 and record with two heads at a channel rate of 8 MHz. The address control circuit 605 controls the write and read addresses of the memory 604, and the data is compressed and read in order to obtain the signal shown in FIG.

Next, the signal processing during reproduction will be described. The signals reproduced by the A magnetic head 502A and the B magnetic head 502B are input from the terminal 610 in the waveform shown in FIG. 10, amplified by the reproduction amplifier 611, and then converted into 8 bits in 10-bit units by the demodulator 612. Then, it is restored to the original digital signal and stored in the memory 613. On the other hand, additional information,
The control information is processed by the sub information reproducing circuit 622. The PCM signal stored in the memory 613 is error-corrected by the decoder 615 in units of one track, and is returned to the original generation order in units of the corrected audio symbols of two tracks, and the DA converter in the next stage. 6
Send to 16. Here, after being converted into an analog signal, a 2-channel reproduced analog signal is output from the terminals 619a and 619b via the low-pass filter 617.

The address control circuit 614 performs memory control for writing demodulated data, reading data for error correction, writing, and reading data to be output to the DA converter 616. Clock generation circuit 61
Reference numeral 8 generates a clock for controlling the entire system.

Memory In the first region, a time as shown in FIG. 13 t ₀
The audio symbol output from the AD converter 603 is stored in the memory 604 during the 30 msec period from ~ t _{4 to} the time.
period t ₄ ~t ₅ performs encoding, the period of time t ₅ ~t ₆ are performed reading the PCM signal included in the recording signal A ₂ is the period of time t ₆ ~t _7, the code again reduction is carried out, the period of time t ₇ ~t ₈ reads the PCM signal subjected to coding is performed.

In the memory second area, signal processing is performed by shifting the signal processing of the memory first area by 30 msec. Writing of audio symbols output from the AD converter 603 and generation of a recording signal alternate between the two memory areas. I am switching to.

As mentioned above, the audio symbol is 90 ° in the non-signal section.
The error is encoded within (7.5 msec) and recorded. Further, the additional information can be similarly encoded and recorded.

Next, in FIG. 14, a symbol clock 702a generated for each symbol is output from the frequency division counter 702, a block clock 703a is generated for each block is output from the frequency division counter 703, and a 196 frequency division counter 704 is output. The timing clock 704a is output every 7.5 msec. Also, a divide-by-2 counter 705
To output an output signal 705a as shown in FIG. The timing generation circuit 706 generates the timing for determining the signal arrangement in one block shown in FIG. 10 by the 6-bit output of the 36-divider counter 703, and the 8-bit output of the 196-divider counter in FIG. The signal area to be recorded on one track is controlled. For example,
In the track format of FIG. 9, when the value of the 196 frequency division counter 704 is 0 to 10, it is a signal processing block for generating a signal in the margin portion, and when it is 11 to 20, it is a signal for recording in the additional information area. Processing clock, 34-
At 161, a signal processing clock for reading the audio symbol and the check symbol in the memory 604 is generated. Also, a divide-by-2 counter 705
Of the output signal 705 of "0", the recording signal is generated,
During the period of "1", signal processing is performed as no signal period.

[Problems to be Solved by the Invention] In the conventional digital magnetic recording / reproducing apparatus as described above,
In order to realize the miniaturization of the system, the smaller the diameter of the drum is, the more advantageous it is. Also, the same pattern is recorded on the tape regardless of the diameter of the drum. Is necessary for. 2 as an example
When a drum with a diameter of 0 mm is used, the distance that the magnetic head traces the tape is 2/3 as compared with the case where a drum with a diameter of 30 mm is used, so the winding angle is 3/2 times 13 times.
By recording or reproducing at 5 ° and a signal channel rate of ⅔, a device compatible with a drum device having a diameter of 30 mm can be realized.

FIG. 2 (M-2) described later shows a recording signal recorded by the magnetic head or a reproduction signal reproduced from the magnetic head at this time. Thus, when the diameter of the drum is changed, the winding angle is changed, It is necessary to record and reproduce a signal at a compression rate according to the diameter of the drum. As shown in the example of the drum having a diameter of 30 mm, a signal section and a non-signal section are created every 90 °, and an arbitrary diameter is created. There was a problem such as not being able to record / playback corresponding to the drum.

The present invention has been made to solve the above problems, and an object thereof is to obtain a digital magnetic recording / reproducing apparatus capable of recording / reproducing without changing the magnetization pattern on the tape even if a drum having an arbitrary diameter is used. And

[Means for Solving Problems] A digital magnetic recording / reproducing apparatus according to the present invention uses an input means for inputting information for identifying a drum diameter and a clock having a frequency corresponding to the drum diameter as input. Output processing means for generating and outputting a recording signal composed of a predetermined bit to be recorded on a track, and a signalless period corresponding to the drum diameter by controlling the count number of the clock corresponding to the identification information of the drum diameter. And a non-signal period generating means for generating.

Further, the digital magnetic recording / reproducing apparatus according to the present invention,
Input means for inputting information for identifying the drum diameter and a clock having a frequency corresponding to the drum diameter are input, and the number of clocks is determined according to the signal acquisition period consisting of a predetermined number of clocks and the identification information of the drum diameter. Signal generating means for generating a window signal having a variable signal acquisition prohibition period, and reproduction signal processing means for returning the digital signal reproduced by the head within the signal acquisition period to the original time axis and outputting it. It is equipped with.

[Operation] In the present invention, since the timing control is performed by the coincidence detection circuit that detects the coincidence between the ROM output and the counter, it is possible to record and reproduce the signal according to the drum diameter with a simple circuit configuration.

[Embodiment] FIG. 1 is a block diagram showing a configuration of a clock generation circuit of a digital magnetic recording / reproducing apparatus according to an embodiment of the present invention, and FIG. 14 when X indicating the number of blocks in a no-signal section is used. The configuration of the circuit corresponding to is shown. In the figure, reference numerals 701 to 708 are the same as those in FIG. One input side of the AND gate 710 is connected to the input terminal 707 of the reference signal H and the other input side is connected to the output side of the reset signal generation circuit 711, and the output side thereof is divided by 10 counters 702, 36. Frequency division counters 703 and 196 Frequency division counters 704 and 2
It is connected to each input side of the frequency division counter 705. The reset signal generation circuit 711 is a ROM 7 that stores the value of the number of blocks X in the non-signal section corresponding to various diameter drums.
12 and the value of the ROM 712 and the value of the 36-frequency division counter 703 and the 196-frequency division counter 704 are determined, and if they match, the coincidence detection circuit 714 that outputs “1” and the NAND gate 715. Composed. The terminal 713 is connected to the ROM 712, and receives a selection signal for selecting the number X of blocks stored in the ROM 712 depending on the diameter of the drum.

Now, the winding angle θ between the tape and the drum for making the patterns on the tape the same, the transmission channel clock f _cf , the block number Y corresponding to the period in which the drum rotates 180 ° and the block number X in the non-signal section are It is determined by the following formula using the diameter D.

θ = 30 / D × 90 degrees (1) f _ch = 9.408 × D / 30 MHz (2) Y = 196 × 2 × D / 30 block (3) X = Y-196 block (4) FIG. 2 is a diagram showing the operation timing of FIG. In the figure, M-2 indicates a portion corresponding to the above X, Y and θ on the signal waveform, and is an example in the case of D = 20 mm. The length of the signal period of one track consisting of 196 blocks is determined by changing the frequency of the channel clock of the recording signal, and the no signal section can be arbitrarily set by the number X of blocks.

FIG. 3 is a diagram showing a parameter table showing concrete numerical values of parameters that change depending on the drum diameter, and the drum diameter D = 30 m.
The parameters obtained by the above equations (1) to (4) for m, 20 mm, and 15 mm are shown below. If the value of the number of blocks X or Y is not an integer, it may be rounded to an integer, but if precision is required, 1 block = 36 symbols, so the fractional part stores the number of symbols in ROM. When D = 20 mm, 65 blocks + 12 symbols (≈ 36 symbols x
0.33 block).

FIG. 4 is a time chart showing the processing contents of the memory.

In the digital magnetic recording / reproducing apparatus configured as described above, the operation will be described below when the drum diameter D = 20 mm.

The value of the number X of blocks of D = 20 mm is the ROM shown in FIG.
Select input terminal 7 if stored at address 0 of 712
Enter 0 from 13. The ROM 712 outputs 65 as the number of blocks 712a and 12 as the number of blocks 712b as the number of blocks X.

In FIG. 2, at time t ₁₀₀ , the 10-frequency dividing counter 702, 36-frequency dividing counter 703, 196-frequency dividing counter 704, 2-frequency dividing counter 705 are all reset and the recording signal of the A magnetic head 502A is reset. Is output. At time t ₁₀₁ , the 36 division counter 703 sets 12, 19
When the divide-by-6 counter 704 reaches 65, the coincidence detection circuit 71
Although a pulse is output from 4, the reset signal is not output from the NAND gate 715 because the output 705a of the divide-by-2 counter 705 is 0. The channel clock input terminal 701 has a channel clock f _ch = 9.408 × 2
/3=6.272 MHz was input, and the drum rotated 135 ° as shown in FIG. 19 at time t ₁₀₂
The divide-by-six counter 704 returns from 195 to 0, the divide-by-2 counter 705 counts up to 1, and the output of the recording signal is stopped. At time t ₁₀₃ , the 36-divider counter 703 and the 196-divider counter 704 respectively show 12 symbols and 65 blocks, and at this time, the NAND gate 715.
The reset clock is output from, the same state as at time t ₁₀₀ is _reached, and the recording signal of the B magnetic head 502B is output.

As described above, although the output of each of the counters 702 to 705 changes in different frequency, the timing generation circuit 706
In this case, since the area of the recording signal is determined based on the value of the counter, the pattern of 196 blocks shown in FIG.
It is formed in a period of 35 °.

At the time of reproduction, the output 705a of the divide-by-2 frequency divider 705 can be used as a window indicating the reproduced signal section, or PCM or additional information can be fetched by using a desired address among addresses 0 to 195 of the 196 frequency divider counter 704. By generating the window of, the playback process can be performed without changing the timing generation circuit even if the drum diameter changes.

FIG. 4 shows a signal processing method in the case where the non-signal section is reduced and the coding time is short, and three systems of memories are used.

In the first memory area, the output of the AD converter is taken in during 30 msec from time t _{10 to} t ₁₁ , and the audio signal included in the recording signal A _{n + 2} is encoded during the period from time t _{12 to} t ₁₃ . After the encoding is finished, the audio symbols generated at the times t _{10 to} t ₁₁ and the check symbols generated by the encoding are read and recorded during the period of the times t _{15 to} t ₁₆ .

As described above, signal acquisition, encoding, and recording signal reading are repeated every 90 msec in the same memory area, and 30 msec in the memory first area to memory third area.
By successively shifting the above processing, audio symbols that are successively generated can be coded and further time-axis compressed and recorded.

In the above embodiment, the case where the number of blocks X is used is shown, but FIG. 5 shows the case where the number of blocks Y is used. In FIG. 5, the 196 frequency division counter 704 and the 2 frequency division counter 705 in FIG. 1 are replaced with a 9-bit binary counter 720 that counts the output of the 36 frequency division counter 703, and the 9-bit output is matched by the reset signal generator 711. To the detection circuit 714 36 division counter 70
3 and the output 703a, and when the number of blocks Y read from the ROM 712 matches, the 10-divider counter 702, 36-divider counter 703, and the 9-bit binary counter 720 are all reset. Further, the timing generation circuit 706 uses a 9-bit binary counter 720.
This can be realized by using 0 to 195 of the output 720a for the signal section control and processing 196 or more as a non-signal section.

FIG. 6 shows an example in which a circuit for detecting the values Y1, ..., Yn corresponding to various drum diameters is provided in place of the coincidence detection circuit of FIG. 5, and the selector 740 selects the corresponding drum diameter. The output 740a of the selector 740 is used as the AND gate 71
The same effect can be obtained by inputting one input side of 0.

Incidentally, it is clear that the selector 740 is not necessary in the device corresponding to only Y ₁ , and it goes without saying that the example using X in FIG. 1 can be realized by the same configuration as that in FIG.

Further, in the above-described embodiment, the value Y obtained by obtaining the number of blocks and the number of symbols corresponding to 180 ° from the reference signal generated once for one rotation of the drum, which indicates the start of the signal, is 19 from this reference signal.
The value X obtained by obtaining the number of blocks and the number of symbols up to the start point of the next signal section is used with the point after 6 blocks as a reference, but the reference signal may be at any position.

For example, if n blocks after the reference signal is used as a reference,
A value Y−n obtained by subtracting n from the value Y obtained by the equation (3) is stored in the ROM, and another counter having a symbol or block clock as an input is provided.
When it matches the value of M, it can be similarly realized by resetting the counters 702 to 705 and starting recording the signal of the B channel.

Also, the same effect can be obtained by externally giving the value output from the ROM.

[Effects of the Invention] As described above, the present invention comprises the input means for inputting the information for identifying the drum diameter and the predetermined bit for recording on one track by inputting the clock of the frequency corresponding to the drum diameter. Output processing means for generating and outputting a recording signal, and no-signal period generation means for generating a no-signal period corresponding to the drum diameter by controlling the count number of the clock corresponding to the identification information of the drum diameter. The present invention further comprises: input means for inputting information for identifying a drum diameter; and a clock having a frequency corresponding to the drum diameter as an input, and a signal acquisition period of a predetermined number of clocks and the drum. Signal generating means for generating a window signal having a signal acquisition prohibition period in which the number of clocks varies according to the diameter identification information; And a reproduction signal processing means for returning the digital signal reproduced by the head to the original time axis and outputting the same within a limited period, and inputting a channel clock having a frequency capable of signal compression corresponding to the drum diameter, Since the timing generation circuit used for the timing generation counter control by designating the number of blocks to be recorded or reproduced within a predetermined time according to the drum diameter is shared, the function can be improved without a large increase in cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing a clock generation circuit of a digital magnetic recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is an operation timing chart of FIG. 1, and FIG. 3 is a specific parameter changing according to a drum diameter. Parameter table showing numerical values,
FIG. 4 is a time chart showing the processing contents of the memory shown in FIG. 1, FIG. 5 is a block diagram showing a clock generating circuit of a digital magnetic recording / reproducing apparatus according to another embodiment of the present invention, and FIG. FIG. 7 is a block diagram showing a clock generating circuit of a digital magnetic recording / reproducing apparatus according to another embodiment of the present invention, FIG. 7 is a layout diagram of a drum, a magnetic head and a magnetic tape of a conventional digital magnetic recording / reproducing apparatus, and FIG. FIG. 9 is a magnetization pattern diagram when a signal is recorded on a magnetic tape by the digital magnetic recording / reproducing apparatus of FIG. 9, FIG. 9 is a signal configuration diagram of one track of the magnetization pattern shown in FIG. 8, and FIG. 10 is a PCM recording area. FIG. 11 is a block diagram of a signal of one block to be recorded, FIG. 11 is a recording / reproducing signal waveform diagram of the conventional digital magnetic recording / reproducing apparatus, and FIG. 12 is a block of the conventional digital magnetic recording / reproducing apparatus. Figure, FIG. 13 timing diagram of a conventional digital magnetic recording and reproducing apparatus, FIG. 14 is a block diagram of a clock generation circuit of a conventional digital magnetic recording and reproducing apparatus. In the figure, 702 ... 10 frequency division counters, 703 ... 36
Frequency division counter, 704 ... 196 Frequency division counter, 705 ...
2 frequency division counter, 706 ... Timing generation circuit, 710
... AND gate, 712 ... ROM, 714 ... Match detection circuit, 715 ... NAND gate. In the drawings, the same reference numerals indicate the same or corresponding parts.

Continuation of the front page (56) References JP-A-60-661 (JP, A) JP-A-62-62476 (JP, A) JP-A-63-213165 (JP, A)

Claims (2)

[Claims] 1. A digital magnetic recording / reproducing apparatus for performing time-axis compression of an input digital signal and recording / reproducing such that a head mounted on a drum together with other signals forms tracks obliquely to the longitudinal direction of the tape. Input means for inputting information for identifying the drum diameter, and output processing means for generating and outputting a recording signal composed of predetermined bits for recording on one track by inputting a clock having a frequency corresponding to the drum diameter, A non-signal period generating means for generating a no-signal period corresponding to the drum diameter by controlling the count number of the clock corresponding to the identification information of the drum diameter, and outputting the recording signal of the predetermined bit. By changing the number of clocks in the subsequent no-signal period according to the drum diameter, the time axis compression corresponding to the drum diameter can be performed. Digital magnetic recording and reproducing apparatus according to claim Ukoto. 2. A signal reproduced by a head attached to a drum from a tape recorded so as to form a track oblique to the longitudinal direction together with other signals by time-compressing the input digital signal. In a digital magnetic recording / reproducing apparatus for time-axis-compressing and outputting the digital signal, input means for inputting information for identifying a drum diameter, and a predetermined clock with a clock having a frequency corresponding to the drum diameter as an input And a digital signal reproduced by the head within the signal capturing period, and a signal generating unit for generating a window signal including a signal capturing period consisting of a number and a signal capturing prohibited period in which the number of clocks varies according to the identification information of the drum diameter. A reproduction signal processing means for outputting the signal back to the original time axis and outputting the digital magnetic field. Recording / playback device.