JPH0519863Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a magnetic recording/reproducing device typified by an R-DAT, a video tape recorder, and the like.

[Summary of the idea]

In the present invention, the level of the tracking error signal for correcting the phase error of the capstan motor is limited.

[Conventional technology]

In R-DAT, 8mm video tape recorders, etc., a pilot signal for tracking is recorded on a tilted track on which original information is recorded and reproduced. Therefore, when reproducing information, a pilot signal is detected, a tracking error signal is generated, and phase servo of the capstan is performed. On the other hand, since a tracking error signal cannot be obtained during information recording, a phase error signal is generated from pulses generated in synchronization with the rotation of the capstan, and phase servo is performed.

[Problem that the invention attempts to solve]

However, if the program recorded on the magnetic tape ends during information reproduction, or if for some reason a correct tracking error signal is no longer generated, there is a risk that the capstan motor will run out of control.

[Means for solving problems]

The present invention provides a magnetic recording/reproducing device that includes a capstan for running a magnetic tape, a motor for rotating the capstan, a pulse generating means for generating pulses synchronized with the rotation of the motor, and a speed error corresponding to the output of the pulse generating means. Speed servo means for generating a signal, tracking means for generating a tracking error signal, addition means for adding the tracking error signal and speed error signal, and drive means for driving the motor in response to the output of the addition means. and a limiting means for limiting the level of the tracking error signal added to the speed error signal.

[Effect]

The capstan motor is driven by a signal obtained by adding the reproduction speed error signal and the tracking error signal. When the level of the tracking error signal exceeds a predetermined range, the level is limited.

〔Example〕

FIG. 2 is a block diagram of the magnetic recording/reproducing apparatus of the present invention. In the figure, reference numeral 1 denotes a rotating head that records and reproduces information by tracing a magnetic tape (not shown) (the recording system is omitted in the figure for convenience). Reference numeral 2 denotes a reproduction means that demodulates and processes the reproduction signal output from the rotary head 1, converts it from a digital signal to an analog signal, and outputs the analog signal. 3 is a tracking means which detects a pilot signal for tracking from the output of the reproducing means 2 and generates a tracking error signal. Reference numeral 5 denotes a control means consisting of a microcomputer or the like, which executes commands inputted from an input means 6 consisting of a keyboard, a switch, etc.

Reference numeral 10 denotes a capstan for running the magnetic tape, and is rotated by a motor 9. 11 is a pulse generating means, which includes a motor 9 (capstan 10);
Generates pulses (PG, FG) synchronized with the rotation of the One pulse per revolution (PG output) outputted by the pulse generating means 11 is input to the phase servo means 12 including a PLL circuit, etc., and a phase error signal is generated. The output of the frequency generator (FG output) output by the pulse generation means 11 is input to the speed servo means 13 including a frequency-voltage conversion circuit, etc., and a speed error signal is generated.

Either the tracking error signal or the phase error signal is selected by the switching means 4 and added to the speed error signal by the adding means 7. Addition means 7
The output of is supplied to a drive means 8 which drives a motor 9.

However, when a recording mode is input from the input means 6, a recording signal is inputted to the rotary head 1 from the recording means (not shown) and recorded on the magnetic tape.
At this time, the control means 5 switches the switch 4 to the contact R side. As a result, a free-running loop is formed.

That is, the pulse generating means 11 outputs PG pulses and FG pulses in synchronization with the rotation of the motor 9 that rotates the capstan 10. After the FG pulse is input to the speed servo means 13 and subjected to F/V conversion,
A speed error signal is generated when compared to a predetermined reference voltage. PG pulse is PLL of phase servo means 12
A phase error signal is generated by, for example, comparing a control voltage of a voltage controlled oscillator that is input to a circuit and constitutes a PLL circuit with a predetermined reference voltage. The phase error signal is inputted to the adding means 7 via the switch 4, added to the speed error signal supplied from the speed servo means 13, and outputted to the driving means 8 as a driving signal. The drive means 8 drives the motor 9 (and thus the capstan 10) in response to the drive signal.

Next, when the input means 6 is operated to enter the playback mode, the playback signal output from the rotary head 1 is input to the playback means 2, which processes this signal, converts it to D/A, and outputs it. . Also, at this time, the control means 5 switches the switch means 4 to the contact P side.

The tracking means 3 generates a tracking error signal from the reproduction signal output from the reproduction means 2.

FIG. 3 shows a more detailed block diagram of this tracking means 3. The reproduced signal is input to the low-pass filter 21, and the pilot signal component f ₁
are separated. This pilot signal is sent to the rectifier circuit 2.
2 (FIG. 4d) and input to a sample hold (S/H) circuit 23 and a differential amplifier 24.

On the other hand, the bandpass filter 25 separates the tracking synchronization signal component f ₂ or f ₃ from the reproduced signal. When the detection circuit 26 detects this synchronization signal f ₂ or f ₃ , it outputs a detection signal (FIG. 4a) to the sampling pulse generation circuit 27 . The sampling pulse generation circuit 27 generates a first sampling pulse (FIG. 4b) in synchronization with the rising edge of the detection signal, and generates a second sampling pulse (FIG. 4c) when a predetermined time has elapsed since then. occurs. The first sampling pulse is output to the sample hold circuit 23, and the second sampling pulse is output to the sample hold circuit 28. On the magnetic tape, at the timing when the first sampling pulse is generated, a pilot signal is reproduced as a crosstalk component from the slope track adjacent to the right, and at the timing when the second sampling pulse is generated, a pilot signal is reproduced from the slope track adjacent to the left. Each signal is recorded so that it is reproduced as a crosstalk component. Therefore, the sample-and-hold circuit 23 samples and holds the level of the pilot signal from the right-adjacent slope track using the first sampling pulse. This hold value is input to the differential amplifier 24, and the difference between it and the output of the rectifier circuit 22 is calculated. At the timing when the second sampling pulse is generated, the output of the rectifier circuit 22 corresponds to the level of the pilot signal from the adjacent slope track on the left, so the differential amplifier 24 outputs the hold value (the level of the pilot signal from the right track). The difference between the level of the pilot signal from the left track and the level of the pilot signal from the left track is output. This level difference is sampled and held by the second sampling pulse in the sample and hold circuit 28. This level difference serves as a tracking error signal.

This tracking error signal is input to the adder circuit 7 and added to the speed error signal from the speed servo means 13. Therefore, the rotation of the capstan (travel of the magnetic tape) is controlled in response to the tracking error signal.

FIG. 1 shows a more detailed circuit diagram of the adder circuit 7. The tracking error signal is transmitted through resistor 3.
1 and 32, a diode 41, an operational amplifier 37, and a bias voltage generation circuit 39, the signal is input to an inverting amplifier (constituting a limiting means) and is inverted and amplified. The amplified signal is passed through an adding resistor 33,
It is added to the speed error signal input via the addition resistor 34. This addition signal is generated by resistors 35, 3
6, operational amplifier 38, bias voltage generation circuit 40
The signal is input to a non-inverting amplifier, amplified and output. The bias voltage generation circuits 39 and 40 that generate the bias voltage E=(Vcc/2) are provided in order to operate the operational amplifiers 37 and 38 in class A with a single power supply (Vcc), and the positive and negative 2
It is not necessary when operating with power supply (±Vcc).

When the rotary head 1 is reproducing the signal recording area, the tracking error signal output by the tracking means 3 is within a predetermined dynamic range D around a predetermined voltage E, as shown in FIG. change within. When the rotary head 1 reproduces an area in which no signal is recorded, no tracking error signal is generated, so the hold capacitor (not shown) of the sample and hold circuit 28 is gradually discharged and its output is reduced. When this voltage drops below a predetermined value, the output of the operational amplifier 37 constituting the inverting amplifier becomes at a higher level than its inverting input, the diode 41 is turned on, and the amount of feedback increases. Therefore, the output of the inverting amplifier is limited to a predetermined value (voltage E and diode 4
1).

If it is desired to prevent the output of the inverting amplifier from becoming smaller than a predetermined value, a bidirectional diode such as a triac may be used as the diode 41.

〔effect〕

As described above, the present invention provides a magnetic recording and reproducing apparatus which includes: a capstan for running a magnetic tape; a motor for rotating the capstan; and a pulse generating means for generating pulses synchronized with the rotation of the motor.
speed servo means for generating a speed error signal in response to the output of the pulse generation means; tracking means for generating a tracking error signal; addition means for adding the tracking error signal and the speed error signal; This device is equipped with a drive means that drives the motor in accordance with the output, and a limiter that limits the level of the tracking error signal that is added to the speed error signal. It is possible to prevent the motor from running out of control.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of the adder circuit of the present invention, Figure 2 is a block diagram of its magnetic recording/reproducing device, Figure 3 is a block diagram of its tracking means, Figure 4 is its timing chart, and Figure 5 is its FIG. DESCRIPTION OF SYMBOLS 1...Rotating head, 2...Reproducing means, 3...Tracking means, 4...Switching means, 5...Controlling means, 6...Inputting means, 7...Adding means, 8...
... Drive means, 9 ... Motor, 10 ... Capstan, 11 ... Pulse generation means, 12 ... Phase servo means, 13 ... Speed servo means, 21 ... Low pass filter, 22 ... Rectifier circuit, 23 ... Sample and hold circuit, 24...Differential amplifier, 25...
...Band pass filter, 26...Detection circuit, 27
...Sampling pulse generation circuit, 28...Sample hold circuit, 31 to 36...Resistor, 3
7, 38... operational amplifier, 39, 40... bias voltage generation circuit, 41... diode.

Claims (1)

[Scope of utility model registration request] A capstan that runs a magnetic tape, a motor that rotates the capstan, a pulse generator that generates pulses synchronized with the rotation of the motor, and a speed servo that generates a speed error signal in response to the output of the pulse generator. tracking means for generating a tracking error signal; addition means for adding the tracking error signal and the speed error signal; driving means for driving the motor in response to an output of the addition means; A magnetic recording/reproducing apparatus comprising: limiting means for limiting the level of the tracking error signal added to the speed error signal.