JPH0630200B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and more particularly, to a noise feeding means for obtaining a noiseless image by a field still system during reproduction in the apparatus.

[Conventional technology]

Conventionally, there is an apparatus of this type shown in FIG. In the figure, 1 is a time constant circuit composed of a capacitor C1 and a resistor R1 for determining the noise feed start time, 2 is a mono-multi signal for creating the noise multi feed signal for determining the noise feed start time by the constant decided by the time constant circuit 1. A multi-creating circuit, 3 is a switch for giving a still signal to the mono-multi-creating circuit 2, 4 is a noise feed start circuit for generating a signal for starting noise feed, and 5 is noise feed for generating a signal for stopping noise feed. A stop circuit, 6 is a dropout shaping circuit that shapes the dropout noise at the time of stillness into a pulse, 7 is a drive circuit of a capstan motor that starts and stops noise feeding, and 8 is a tape running system.

Next, the operation will be described.

The still signal is generated by the switch 3 and the mono-multi circuit 2 is created.
When the input signal is input to, the charging is started by the time constant of the capacitor C1 and the resistor R1 at the same time as the rising of the still signal, and the monomulti signal is created by the threshold voltage VTH of the monomulti creating circuit 2. Then, the noise feed starting circuit 4 starts its operation at the fall of the mono-multi signal output from the mono-multi creating circuit 2. Then, a pulse having a certain width, which is the output thereof, is input to the capstan coater drive circuit 7, and the tape is intermittently fed by the pulse to send noise. In the noise feed stop circuit 5, almost 100% of the time corresponding to one field
A pulse provided at a certain level, that is, a pulse provided at a time point delayed by about one field from the rising time point of the drum rotation signal (head switching signal), and a pulse pulse-shaped waveform of noise by the dropout shaping circuit 6. If and match, a match pulse is output, and the match pulse is input to the capstan motor drive circuit 7 to stop tape running and noise feed. In this way, a noiseless still reproduction image is obtained.

[Problems to be solved by the invention]

The conventional device is configured as described above, and it may not be possible to send noise or may be excessively sent. In order to suppress this, it is necessary to start the noise feed in anticipation of the time required for the capstan motor to stop at the time of still, but considering the fact that the speed search changes to the still state, it is quite wide. It becomes necessary to manage time constants across a range. In addition, since there are variations in the accuracy of the VTR set (each component), etc., if one tries to manage the time constant in consideration of this as well, it will not be possible to absorb them, and noise feeding will be extremely difficult. There were drawbacks such as being stable.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional ones, and an object thereof is to provide a magnetic recording / reproducing apparatus capable of reliably feeding noise and obtaining a stable noiseless still image.

[Means for solving problems]

A magnetic recording / reproducing apparatus according to the present invention comprises a noise feeding means for driving a capstan motor by inputting a still signal to intermittently feed a tape to feed noise, and an FG signal output according to rotation of the capstan motor. The stop of the capstan motor is detected by the drive, the drive of the capstan motor is started after a certain time from the detection of the stop, and the above-mentioned cap is detected by the comparison result between the noise of the reproduction signal reproduced by the magnetic head and the magnetic head switching signal. The drive of the stun motor is stopped.

[Operation] In the present invention, the noise feed means is started after the stop detection of the capstan motor is detected, and the noise feed means is stopped based on the noise detection of the reproduction signal from the magnetic head. In both normal playback and speed playback, the same time constant can be used to obtain a noiseless still playback image with the minimum required stop time, and the drive characteristics of the capstan motor and the tape position may change. However, the tape can be stopped at the optimum still reproduction start position without being affected by this.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 10 is a motor stop detection circuit for detecting the rotation stop of the capstan motor that runs the tape depending on the presence or absence of the FG signal. It constitutes a noise feed starting means for starting. Where F
The G signal is output by an FG (frequency oscillator) provided in the capstan motor according to the rotation of the motor. Then, in the motor stop detection circuit 10,
T is an NPN transistor, R3 is a resistor connected to the base of the transistor T, R4 is a resistor connected between the base of the transistor T and ground, R2 is a load resistor connected between the collector of the transistor T and the power supply Vcc, C2 Is a capacitor connected between the collector of the transistor T and ground,
D is a diode connected between the collector of the transistor T and the time constant circuit 1.

Other configurations are the same as those of the conventional circuit, 1 is a time constant circuit for determining the noise feed start time, 2 is a mono-multi signal for determining the noise feed start time by the constant determined by the time constant circuit 1. A mono-multi producing circuit 3, a switch for giving a still signal to the mono-multi producing circuit 2, 4 a noise sending start circuit for generating a signal for starting noise feeding, and 5 a noise for generating a signal for stopping noise feeding A feed stop circuit, 6 is a dropout shaping circuit for shaping the noise used to stop the noise feed in a pulse shape, and 7 is a signal from the noise feed start circuit 4 and the noise and stop circuit 5 for tape running. Capstan motor drive circuit to control, 8
Is a tape running system.

Further, FIG. 2 is a timing chart diagram for explaining the operation of the present embodiment. In addition, reference numerals c to g in FIG.
It corresponds to the signals c to g shown in FIG.

Next, the operation will be described.

The still signal is generated by the switch 3 and the mono-multi circuit 2 is created.
2 (see FIG. 2 (c)), charging is started by the time constant of the capacitor C1 and the resistor R1 of the time constant circuit 1. However, the capstan motor does not stop at the same time when the still signal rises, and therefore slightly runs the tape. In this way, when the motor is rotating, the FG signal is input to the base of the transistor T of the motor stop detection circuit 10, so that the mono-multi signal to be generated by the mono-multi creation circuit 2 is erased. When the capstan motor is completely stopped, the transistor T is completely turned off, and the transistor T is completely turned off by the still signal c and the signal d generated by the motor stop detection circuit 10 as shown in FIG. 2 (d). Is formed, and the mono-multi signal e as shown in FIG. 2 (e) is output from the mono-multi creating circuit 2.

The noise feed start circuit 4 operates from the trailing edge of the mono-multi signal e, and a pulse f having a certain width as shown in FIG. 2 (f) is output, which is input to the capstan motor drive circuit 7, Causes the tape to be sent intermittently. A pulse (see FIG. 2 (b)) provided in about 100% of one field in the noise feed stop circuit 5, that is, a drum rotation signal (head switching signal) a as shown in FIG. 2 (a). A pulse b which is always generated at the time when a delay of approximately one field is generated from the rising edge, and a pulse g whose noise is shaped by the dropout shaping circuit 6.
If it matches (see FIG. 2 (g)), a match signal is input from the noise feed stop circuit 5 to the capstan motor drive circuit 7, whereby the tape running is stopped and the noise feed is stopped. In this way, a still reproduced image without noise can be obtained.

As described above, in the apparatus of this embodiment, the noise feed start at the time of still reproduction is performed by detecting the stop of the capstan motor. Therefore, in the case of either still from normal reproduction or still from speed search reproduction, Moreover, with the same time constant, a reliable and highly accurate noiseless still image can be obtained with a minimum required stop time.

〔The invention's effect〕

As described above, according to the present invention, the start of noise feeding is
Start after detecting the stop of the capstan motor,
Since the noise feeding is stopped based on the noise detection of the reproduction signal from the magnetic head, there is an effect that the noise feeding can be surely performed and a stable noiseless still reproduced image can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus for feeding noise according to an embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of the apparatus, and FIG. 3 is a conventional magnetic recording. It is a block block diagram for noise feeding of a reproducing device. 1 …… Time constant circuit, 2 …… Monomulti circuit, 4 ……
Noise feed start circuit, 5 ... Noise feed stop circuit, 6 ...
… Dropout shaping circuit, 7… Capstan motor drive circuit. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A magnetic recording / reproducing apparatus for performing noiseless field still reproduction, comprising noise feeding means for driving a capstan motor by inputting a still signal to intermittently feed a tape to feed noise. In accordance with the FG signal output in accordance with the above, noise feed starting means for detecting the stop of the capstan motor and starting driving of the capstan motor after a fixed time, and noise of the reproduced signal reproduced by the magnetic head A magnetic recording / reproducing apparatus comprising: a noise feed stopping means for stopping driving of the capstan motor when a predetermined phase is reached with respect to a magnetic head switching signal.