JPS6390050A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain accurate search by controlling a rotational speed by the frequency change of a reference signal and fixing the speed of a rotary head at a constant value in a non-signal part. CONSTITUTION:A D-flip flip (FF) 19 outputs an 'H' level signal when a recording signal exists on a magnetic tape 1, and in a non-signal part outputs an 'L' level signal. A change-over switch 20 sends an output of a maximum value holding circuit 14 to a subtractor 22 when an input from the FF 19 is in an 'H' level, and in case of an 'L' level, sends an output from an ideal value generating circuit 21 to the circuit 22. The circuit 22 outputs a difference between the ideal value and a value inputted through the switch 20 to a drum control circuit 24 as an error signal. The circuit 24 controls the rotational speed of a drum 15 based on the error signal obtained from the circuit 22 so that the frequency of an automatic track finding signal is equal to the frequency required at the time of recording. Since the rotational speed is fixed in the non-signal part, accurate search can be attained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is characterized in that a reference signal is recorded as a subcode signal on a magnetic tape, and when the magnetic tape is played back, a reference signal is recorded as a subcode signal. The present invention relates to a magnetic recording/reproducing apparatus configured to control the rotational speed of the rotary head, and particularly to a rotary head type magnetic recording/reproducing apparatus capable of performing a search while running a magnetic tape at high speed.

(Prior Art) Conventionally, a magnetic recording and reproducing system has been designed in which a detection signal is recorded on a magnetic tape, and by detecting this signal, the beginning of the recorded signal recorded on the magnetic tape is found. A device has been proposed.

Among such magnetic recording and reproducing devices, those using a rotating head read the detection signal recorded on the magnetic tape, and based on this signal, the rotational speed of the rotating head and the running speed of the magnetic tape are determined. need to be synchronized.

That is, if the rotational speed of the rotary head is constant, the relative speed between the rotary head and the magnetic tape, including its direction, will be different from that during recording. Therefore, the frequency of the reproduced signal also fluctuates accordingly, and P L L (I'haseLocded Loc) for demodulating the digital signal occurs.
operation range may be exceeded. Therefore, if you start cueing in this state, the speed of the magnetic tape will differ between the beginning and the end of the magnetic tape and the error will become large.In order to reduce this error, the rotational speed of the rotary head should be adjusted to the speed of the magnetic tape. It is necessary to change (ideally synchronize) according to the driving speed.

(Problem to be Solved by the Invention) However, when attempting to search a magnetic tape in which there is a no-signal portion (i.e., a portion where no detection signal exists on the magnetic tape) between recorded signals, When this no-signal portion is reached during a search, there is no control signal (signal for detection), making it impossible to control the rotational speed of the rotary head, which poses a problem in that an accurate search cannot be performed.

(Means for Solving the Problems) In the magnetic recording and reproducing apparatus of the present invention, a reference signal is recorded as a subcode signal on a magnetic tape, and when the magnetic tape is reproduced, it is based on the recorded reference signal. In the magnetic recording/reproducing apparatus, the rotational speed of the rotary head is controlled in accordance with a frequency change of the reference signal when the magnetic tape runs at high speed; When the magnetic tape reaches a portion where the reference signal is not recorded, the rotation speed of the rotary head is fixed constant.

(Function) When the magnetic tape runs at high speed, a reference signal recorded as a subcode signal on the magnetic tape is detected, and the rotational speed of the rotary head is controlled in accordance with the frequency change of the reference signal. Furthermore, when the magnetic tape reaches a portion where the reference signal is not recorded (no-signal portion), that is, when the mj rotary head reaches the no-signal portion, the rotational speed of the rotary head at that point is set to zero. Fixed during the signal part. This results in
When the magnetic tape reaches the part where the reference signal is recorded again, the rotational speed of the rotary head can be smoothly controlled by the reference signal, and an accurate search can be performed.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of a magnetic recording/reproducing apparatus according to the present invention.

In the figure, 1 is a magnetic tape, 2 is a rotating head, and 3 is a magnetic tape.
is a head amplifier, 4 is a waveform shaping circuit, 5 is a reference signal detection circuit, 6 is an envelope detection circuit, 7 is a slice circuit,
8 is an AND circuit, 9 is a section pulse detection circuit, 10 is a clock counter, 11 is a minimum value detection circuit, 12 is a minimum value holding circuit, 13 is a maximum value detection circuit, 14 is a maximum value holding circuit, 15 is a rotating drum, 16 is a drum rotation detection circuit, 17
18 is an SR-flip-flop, 18 is an N-divider circuit, 19 is a D-flip-flop, 20 is a changeover switch, 21 is an ideal value generation circuit, 22 is a subtraction circuit, 23 is a D/A conversion circuit, and 24 is a drum control circuit. It is.

Further, FIG. 2 shows a recording pattern of signals recorded on the magnetic tape l using the rotary head section 2. As shown in FIG.

In the same figure, information such as a music signal is recorded on a recording track 1a, and recording tracks lb, lb on both sides of this recording track 1a have ^, T, F (Automatic
IC Track Finding) signal (130
k) 1z analog signal) is recorded. Also, I
C is a portion where no signal is recorded (no signal portion). The ^, T, and F signals are used to control the rotational speed of the capstan motor (not shown) and the rotary head section 2 so that the recording signal can be read accurately.

Next, while running the magnetic tape 1 at high speed, the A and T
, P signal and performs cueing operation will be explained.

Signals recorded on a magnetic tape 1 running at high speed are read by a rotating head section 2 and amplified by a head amplifier 3. The signal amplified by the head amplifier 3 is sent to the waveform shaping circuit 4
After the waveform is shaped by A, the reference signal detection circuit 5
, T, and F signals are detected. This detected A, T
, F signal is transmitted through the enrope detection circuit 6 and the slice circuit 7.
are input respectively. Here, the output waveform of the envelope detection circuit 6 is shown in FIG. 3(ta+), and the output waveform of the slice circuit 7 is shown in FIG. 3(b). These signals are input to an AND circuit 8. The AND circuit 8 outputs the output from the slice circuit 7 as is only while the envelope is being detected by the envelope detection circuit 6. This AND
Signals from the circuit 8 are supplied to a clock counter 10 and a section pulse detection circuit 9, respectively. The clock counter 10 counts the reference clock from the rising edge of the human input signal from the AND circuit 8 to the next rising edge, and outputs the counted value to the minimum value detection circuit 11.

On the other hand, the interval pulse detection circuit 9 also receives a signal from the envelope detection circuit 6, is reset at the rising edge of the signal from the envelope detection circuit 6, and starts counting the pulses of the signal from the AND circuit 8. For example, the output signal from the input of the second pulse to the input of the fourth pulse is set to the rHJ level, and when the fourth pulse is input, the output signal is set to the rLJ level.

The minimum value detection circuit 11 compares the count value from the clock counter 10 with the previously detected and held value, and determines that the current input value is smaller and that the input from the interval pulse detection circuit 9 is at the rHJ level. In certain cases, the current count value is held and output to the minimum value holding circuit 12. Note that if the current count value is larger than the previous value, the minimum value detection circuit 11 holds the previous value. In addition, the minimum value detection circuit 1
The held value of 1 is cleared by an output pulse from the drum rotation detection circuit 16 (see FIG. 3 tc+) which outputs one pulse every two rotations of the rotating drum 15.

The minimum value holding circuit 12 holds the value before the output of the minimum value detection circuit 11 is cleared using the output pulse from the drum rotation detection circuit 16, and outputs this value to the maximum value detection circuit 13.

The maximum value detection circuit 13 compares the previously held value with the input value from the minimum value holding circuit 12, and if this input value is larger than the previous held value and there is an output pulse from the drum rotation detection circuit 16. The input value from the minimum value holding circuit 12 is held, and this input value is output to the maximum value holding circuit 14. Furthermore, the value held by the maximum value detection circuit 13 is determined by the N frequency division circuit 1.
Cleared by the output pulse from 8 [see Figure 3 (dl)].

The maximum value holding circuit 14 holds the input value from the maximum value detection circuit 13 using the 'input pulse from the N frequency dividing circuit 18, and outputs it to the terminal a of the changeover switch. Note that the N frequency dividing circuit 18 divides the frequency of the input from the drum rotation detection circuit 16 by N and outputs the result.

The SR-flip-flop 17 is set at the rising edge of the signal waveform from the envelope detection circuit 6 (tl in FIG. 3), and is set at rH from the output terminal Q at 2 even with a delay.
It outputs a J level signal, is reset at the rising edge (t3) of the pulse signal from the drum rotation detection circuit 16, and outputs an rLJ level signal from the output terminal Q at t4 with a delay [see Fig. 3 (el) ].

The D-flip-flop 19 is connected to the SR-flip-flop 1 at the rising edge of the pulse signal from the N frequency divider circuit 18.
The input signal from 7 is held [see Fig. 3 jfl]. That is, when the pulse from the N frequency divider 18 is input at t3, the output of the SR-flip-flop 17 at that time is still at the rHJ level due to the delay, so the output from the output terminal Q of the D-flip-flop 19 is The output is delayed from the pulse input from the N frequency divider circuit 18 and reaches the rHJ level at t4. Since the output of the SR-flip-flop 17 is at rLJ level at the rising edge of the pulse from the N-divider circuit 18 (t5), the output of the D-flip-flop 19 is delayed from the pulse input from the N-divider circuit 18. then t
6 is the rLJ level. Note that the above signal processing uses the delay of the flip-flop itself, but if this delay time is not sufficient, the SR-flip-flop 1
An appropriate delay circuit (not shown) may be inserted between D-flip-flop 7 and D-flip-flop 19. As a result, the D-flip-flop 19 outputs a signal at the rHJ level when there is a recording signal on the magnetic tape 1, and outputs a signal at the rHJ level when there is no signal.
A J level signal will be output.

The changeover switch 20 is configured to switch the input from the D-flip-flop 19 to the rHJ level, that is, to send the output of the maximum value holding circuit 14 to the subtraction circuit 22 in the recording portion of the magnetic tape 1 (terminals a to C). -Flip-flop 1
When the input from 9 is at the rLJ level, that is, in a no-signal portion, the output from the ideal value generating circuit 21 is switched to be sent to the subtracting circuit 22 (terminals b-c).

The subtraction circuit 22 uses the difference between the ideal value and the value input via the changeover switch 20 as an error, and outputs the difference to the D/A conversion circuit 23.
Output to. The D/A conversion circuit 23 converts the digital output from the subtraction circuit 22 into an analog signal and outputs it to the drum control circuit 24 as an error signal. Drum control circuit 24
A, based on the error signal from the D/A conversion circuit 23,
The rotational speed of the rotary drum 15 is controlled so that the frequencies of the T and F signals are equal to the recording frequency.

(Effects of the Invention) As explained above, according to the magnetic recording and reproducing apparatus of the present invention, when the magnetic tape reaches a no-signal section, the rotational speed of the rotary head is fixed at that point, so that the next It is possible to improve the responsiveness of controlling the relative speed between the rotary head and the magnetic tape when reading necessary information from the recorded portion.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a magnetic recording and reproducing apparatus of the present invention;
FIG. 2 is a diagram showing a recording pattern of a magnetic tape, and FIG. 3 is a diagram showing signal waveforms at various parts of the magnetic recording/reproducing apparatus shown in FIG. 1. 1... Magnetic tape 2... Rotating head section 3.
...Head amplifier 4...Waveform shaping circuit 5...
Reference signal detection circuit 6...Envelope detection circuit 7...Slice circuit 8...AND circuit 9...
- Section pulse detection circuit 10...Clock counter 11...Minimum value detection circuit 12...Minimum value holding circuit 13...Maximum value detection circuit 14...Maximum value holding circuit 15...Rotating drum 16 ...Drum rotation detection circuit 17...SR-flip-flop 18...N frequency division circuit 19...D-flip-flop 20...Switch switch 21...Ideal value generation circuit 22...Subtraction Circuit 23...D/A conversion circuit 24...Drum control circuit

Claims (1)

[Claims] 1) A reference signal is recorded as a subcode signal on a magnetic tape, and when the magnetic tape is reproduced, the rotational speed of the rotary head is controlled based on the recorded reference signal. In the magnetic recording and reproducing device made, when the magnetic tape runs at high speed, the rotational speed of the rotary head is controlled in response to a frequency change of the reference signal, and the magnetic tape is configured such that the reference signal is not recorded on the magnetic tape. 1. A magnetic recording and reproducing apparatus, characterized in that the rotational speed of the rotary head is fixed constant when the rotational head reaches a certain point.