JPS58139353A - Recording medium driving device - Google Patents

Abstract

PURPOSE:To reduce the time to be stable (settling time), by sampling an output of a reference period function generator with a servo pulse, providing an output to a drive control circuit, and controlling the moving phase of a recording medium. CONSTITUTION:A servo pulse P1 is applied to a sample hold circuit 4 being a phase comparator as a sampling pulse. A reference period function signal P2 is applied to the circuit 4 from a reference period function generator 6. A clock CK is given from a clock generating circuit 5 to the circuit 6 and a reference signal P2 is formed based on the clock CK. A phase error signal generated from the circuit 4 is applied to a summing circuit 7 to be summed with a speed error signal from a speed detection circuit 8. A pulse having a frequency proportional to the number of revolution is applied to the circuit 8 from a tachogenerator 9 rotated incorporatedly with a capstan motor 12 and the speed error signal in response to the frequency of the pulse is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording medium drive device that controls the motion phase of a recording medium such as a magnetic tape, magnetic disk, or the like.

For example, when recording and reproducing digital audio signals using a fixed head using a magnetic tape, the magnetic tape is run at a specified speed, and a servo pulse for phase detection at a constant frequency is applied to a control track extending in the longitudinal direction of the magnetic tape. is recorded, and during reproduction, this servo pulse is reproduced, its phase is compared with the servo reference signal, and the comparison output controls the rotational speed of the capstan motor, thereby controlling the running of the magnetic tape.

By the way, when sprite editing or simple electronic editing using full-width erasure is performed, the phase of the servo pulse reproduced at the joint of the signal becomes discontinuous, and a large phase difference may occur between the servo pulse and the servo reference signal. This phase difference is corrected after a predetermined period of time, but in the process, the running speed of the magnetic tape changes more than the specified speed, and the frequency of the reproduced data also changes correspondingly with the speed change. Problems arise in that extraction cannot be performed or that a time base error cannot be corrected by a TBC (time base correction device).

The purpose of this invention is to suppress the change in running speed at the joint of a magnetic tape during playback when the phase of the servo pulse becomes discontinuous at the joint due to splice editing or simple electronic editing as described above. It is. The present invention is also applicable to cases in which video signals are recorded and reproduced in addition to audio signals, and to cases in which recording and reproduction are performed using a rotary head.

In one embodiment described below, the present invention is applied to a fixed head type PCM tape recorder. As shown in FIG. 1, in this example, j data tracks TD to TD7 and two analog tracks 'r*i
, TAL, a control track Tc, and a time code track TT.

In this one data track TD, -TD, each audio PCM signal of the j channel is recorded by predetermined encoding. As shown in FIG. 2A, the recording positions of the data track TD (TDoNTD7) and the control track TC' coincide with each other in the width direction in l sector units. Data of $2a is included in the l sector of the data track TD. Figure 2B
As shown in Figure 2, the / transmission block (simply / / (referred to as pugasatsuku) is constructed. In the data synchronization signal section, 2a of 3-pits F
A mixed address signal is inserted, and both the output address signal and the data are subject to error detection by C'RC. Also, Conte Seal Track Tc
1 sector consists of a t-bit synchronization signal (indicated by a hatched area), a 76-bit control word, a d-bit sector address signal, and a 16-bit CRC code. control) w-word is the sampling frequency of the PCM audio signal to be recorded, recording 7
This is for identifying Omatsu F, and the sector address is O
This is an absolute address that is incremented from the address, and this control word and sector address are subject to error detection by CRC. As a modulation method for recording on the data track TD, a method capable of high-density recording such as the 3PM method is used.As a modulation method for recording on the control track TC, a method such as the FM method is used. It will be done. Least significant bit 19 of sector address signal
6 is made to match the most significant bit of each block address signal of the double block included in that sector. In other words, the block address [BtBo) is [8@'00] (8oO/
]C5o10) (8o//).

As shown in FIG. 3, the head arrangement is such that the recording head HR1, the reproducing head HP, and the recording head HR are positioned in sequence with respect to the running direction of the magnetic tape 1. Each head has 70 heads arranged in-line in the width direction of the magnetic tape 1.
It has g magnetic gaps for recording or reproduction, g of which correspond to data tracks TD6 to TD,
The other two correspond to the control seal track TC and the time code track TT, respectively. The first recording on the magnetic tape 1 is performed by the recording head HR, and the recording head HR is used for sync recording, cut-in/out, etc. The track TC once formed by the recording head HR is not rewritten, but only the data track is rewritten.

For the control track TC described above, a recording/reproducing CTL head shown at 2 in FIG. 1 is provided. The reproduction signal of the C''I'L head 2 is supplied to the control signal detection circuit 3 via a reproduction amplifier, a demodulation circuit, etc. (not shown), and a double servo pulse is taken out as its output.Control The f-hoharus P1 is generated at a rate of one per sector corresponding to the timing at which the synchronization signal of the track TC is detected.This servo pulse P1
is supplied as a sample pulse to a sample hold circuit 4 serving as a phase comparator.

The sample and hold circuit 4 is supplied with a reference periodic function, for example, a reference signal P2 whose digital signal value gradually increases with time, from a reference periodic function generation circuit 6. The reference periodic function generating circuit 6 is supplied with the VCK CK from the p-tower generating circuit 5, and the reference signal P2 is generated based on this clock CI. Here, the frequency f1 of the servo pulse P1 when the traveling speed of the magnetic tape 1 is the specified one in the forward operation is an integral multiple of 2 or more, for example, a multiple (4'
The reference signal P2 has a frequency f2 of ft). In other words, within one period of the servo pulse P1, the reference signal P
It will include two cycles, and the servo pulse P1 will be:
A signal having one of these cycles is sampled.

The phase error signal generated from the sample-and-hold circuit 4 is supplied to an adder circuit 7, where it is added to the speed error signal from the speed detection circuit 8. This speed detection circuit 8 includes a tacho generator 9 that rotates together with the capstan motor 12.
, a pulse with a frequency proportional to the rotational speed is supplied, and a speed error signal with a magnitude corresponding to the frequency of this pulse is generated. Since the error signal obtained from the output of the adder circuit 7 is a digital signal, it is converted into an anamig signal by the "/A conversion circuit 10," and is sent to the DC motor configuration via a Schieha X filter (not shown) and a servo amplifier 11. The signal is supplied to the cab motor 12.The speed error may be detected from the frequency of the servo pulse P1.

To further explain one embodiment of the present invention, as shown in FIG. 3, an m-bit counter 13 and a D-type flip 7
The sample hold circuit 4 and the reference periodic function generation circuit 6 described above are realized by the 0-tube circuit 15.

The counter 13 is supplied with four clocks CK from the terminal 14, and m from the most significant bit Ql to the least significant bit.
The output is repeatedly generated from all bits being 0's to all bits being l's.

The (m-j) bits of the counter 13 excluding the upper two bits Q1 and Q2 are used as the reference signal P2. Figure A shows the top two of the outputs of the counter 13.
Bit Q1, (indicates the change in h, which represents q modes from 0 to 3.

In addition, Fig. B shows the output pitch of the counter 13) Qs~
Changes in the axes (reference signals p and o) are converted into analog values and shown. These output bits Q3 to Qln range from a negative value to a positive value by 2, for example, with O as the center.
It changes in m-2 steps. Click C
If the frequency of K is f3, then (f.

= νtXt, ).

The D-type 7-rip flip circuit 15 consists of m D-type 7-rip 70 flips of l)tNpm, each of which is supplied with the m-bit output of the counter 3 mentioned above as its data input, and the 7-rip 7o flip 1) x -A clock CK is supplied as the first clock input, and a servo pulse P1 is supplied to the p-clock enable terminal, and at the timing of this servo pulse P1, the output of the counter 3 is taken in by the clock & CK, and as R1 to RIn. Output. The servo pulse P1 transmits the reproduction control signal shown in FIG. 7A from the terminal 16 to the D-type flip 70 knob 17.1.
8, an inverter 9, and a NAND gate 20. In other words, from inver 19 to l
A pulse delayed by a clock period and inverted (FIG. 7B) is produced, and a pulse delayed by a clock period (FIG. 7C) is produced from the 7-lip-flop 18, both of which are supplied to the NAND gauge 20. As a result, a signal pulse P1 having a pulse width of one click period at the timing of the falling edge of the reproduced fund roll signal as shown in FIG. 7 is formed.

FIG. 6C shows an example of the servo pulse P1. The running of the magnetic tape is the reference signal P! When the phase is completely locked to the reference signal P! The value of O is sampled by the servo pulse P1, and when a phase shift exists, the 7-rip 7p-tub circuit 15 generates a value that causes a speed change to correct the phase shift. The second figure shows the sampling outputs R3 to Rm generated from this 7-rib, 70-tube circuit 15 converted into analog values. Further, the upper two bits of the output of the 7-rip, 70-tube circuit 15 indicate the mode to which of the l reference signals the phase is locked, as shown in FIG.

Here, because of the splice editing, if the phase of the reproduced servo pulse P10 changes rapidly as shown in Figure C, the locked state to the O mode is released. In the illustrated example, the fourth reference signal and the servo pulse p+ are phase-compared, that is, the 3 mode is established, and the initial state is a high level signal from the 7-rip 7p-tub circuit 15 as shown in the 6th diagram. Sampling output R3~
Rm is generated, and its upper two bits R1 and R
1 indicates the p-tock mode, as shown in Figure E. The phase of the servo pulse P1 generated thereafter is compared with the fourth reference signal, and after a predetermined time, the magnetic pulse 1
The running condition of No. 1 becomes stable.

Note that as the reference signal P2, one having a waveform as shown in FIG. 1 can be used. Figures 1A and 1B are
The trapezoidal waveform is shown in FIG. 1C, and the first diagram is a sine waveform. When the sample and hold circuit 4 has an analog configuration consisting of a switching element and a holding capacitor, an analog waveform is used as the reference signal P2, and when it has a digital configuration as described above, the value is digitally determined. A changing signal is used. 1' As understood from the above description of the embodiment, according to the present invention, the maximum value of the speed change of the recording medium that occurs when the phase of the reproduced servo pulse changes discontinuously can be reduced. The time taken to reach a stable state (settling time) can be shortened. If the number of reference signals is n, the maximum value of speed change is (n = /
) can be suppressed to 1 compared to the case of

[Brief explanation of drawings]

1 and 2 are schematic diagrams used to explain the track pattern and data structure of a multi-channel tape recorder to which the present invention can be applied; FIG. 3 is a route map showing the head arrangement; FIG. 5 is a block diagram showing a specific structure of an embodiment of the present invention; FIGS. 7 and 7 are time charts used to explain the operation of an embodiment of the invention; FIG. 1 is a waveform diagram showing a modified example of the reference signal. 1...magnetic tape, 2...CTL hefdonode...sample hold circuit, 6...
...Reference cycle period 1 sporadic generation circuit, 12... Capstan motor. Agent Masaaki Sugiura Figure 2 Figure 4 Figure 5 1

Claims (1)

[Claims] A reference periodic function generator comprising means for detecting a servo pulse for phase detection of a recording medium from the recording medium and a circuit for driving control of the recording medium, and having a frequency that is an integral multiple of 2 or more of the frequency of the servo pulse at a predetermined speed. A recording medium driving device that samples the output of the recording medium using the servo pulse and applies the sampling output to the drive control circuit to control the motion phase of the recording medium.