JPH10172198A - Magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a correct VISS signal even when reproducibility of a waveform of a control signal is wrong by providing a capstan FG detecting circuit and a threshold level variable circuit. SOLUTION: The control signal recorded on a magnetic tape 11 in the longitudinal direction is amplified by a control signal amplifier circuit 13. A VISS discriminating signal required for discriminating whether the input control signal is the VISS signal or a normal signal is generated by a VISS discriminating signal generating circuit 14. The duty of the VISS discriminating signal is measured by a VISS detecting circuit 15 to decide the VISS signal or the normal signal. The number of revolutions of a capstan 17 for traveling the magnetic tape 11 is detected by the capstan FG detecting circuit 18, and a threshold level in the VISS discriminating signal generating circuit 14 is variably controlled by the threshold variable circuit 16 when the number of revolutions of the capstan 17 exceeds a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for determining whether a control signal is a VISS signal or a normal signal.

[0002]

2. Description of the Related Art A conventional magnetic recording / reproducing apparatus will be described below.

FIG. 2 is a block diagram relating to a VISS detection function in a conventional magnetic recording / reproducing apparatus. In FIG. 2, reference numeral 21 denotes a magnetic tape, and reference numeral 22 denotes a magnetic tape.
A control head for reproducing a control signal recorded in the longitudinal direction of the control head;
A control signal amplifying circuit for amplifying the control signal from the control signal amplifier 24 generates a VISS determination signal necessary for determining whether the control signal amplified by the control signal amplifying circuit 23 is a VISS signal or a normal signal. In the VISS determination signal generation circuit, the threshold level for generating the VISS signal is a fixed value. 25
A VISS detection circuit measures the duty of the signal generated by the VISS determination signal generation circuit 24 and determines whether the signal is a VISS signal or a normal signal.

The operation of the conventional magnetic recording / reproducing apparatus configured as described above will be described below.

In FIG. 2, a control signal recorded in the longitudinal direction of the magnetic tape 21 is transmitted to the control head 2.
Play with 2. The reproduced control signal is amplified by the control signal amplifying circuit 23 and input to the VISS determination signal creating circuit 24. In VISS discrimination signal generating circuit 24, a control signal as shown in FIG. 3 (a) to be input, to create a VISS discrimination signal as shown in Figure based on the threshold level V _t1 3 (b). VIS created
The S determination signal is input to the VISS detection circuit 25, and the duty is measured to determine whether the signal is a VISS signal or a normal signal.

[0006]

However, in the above-mentioned conventional configuration, when the magnetic tape is running at a high speed, FIG.
As shown in (a), the waveform reproducibility of the control signal output from the control signal amplifier circuit 23 deteriorates,
When you create a VISS discrimination signal based on the threshold level V _t1 of FIG from such signals VISS discrimination signal generating circuit 24 4 (a), will not become a desired duty as shown in FIG. 4 (b), VISS detection circuit VISS at 25
There was a problem that detection was not performed correctly.

The present invention solves the above-mentioned conventional problems. A VISS discrimination signal generating circuit makes a threshold level variable so that a correct VISS discrimination signal can be generated even when waveform reproducibility of a control signal is poor. It is an object of the present invention to provide a magnetic recording / reproducing apparatus capable of performing the above-mentioned operations.

[0008]

According to the present invention, there is provided a control signal amplifying circuit for amplifying a control signal recorded in a longitudinal direction of a magnetic tape, and an output from the control signal amplifying circuit. VIS based on a predetermined threshold level of the control signal
A VISS determination signal generation circuit for generating an S determination signal, and a VISS determination signal generated by the VISS determination signal generation circuit.
A capstan for running the magnetic tape, a capstan FG detecting circuit for detecting the number of revolutions of the capstan, and a capstan for detecting the VISS signal by measuring the duty of the discrimination signal; FG
A threshold level variable circuit for controlling a threshold level in the VISS signal determination signal generation circuit when the rotation speed of the capstan exceeds a predetermined value in a detection circuit.

With this configuration, it is possible to create a correct VISS discrimination signal even when the waveform of the control signal in the control signal amplifier circuit is poor.
VISS detection can be performed correctly.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a control signal amplifier circuit for amplifying a control signal recorded in the longitudinal direction of a magnetic tape, and a signal output from the control signal amplifier circuit. A VISS determination signal generation circuit for generating a VISS determination signal based on a predetermined threshold level of the control signal;
A VISS detection circuit for measuring the duty of the VISS determination signal generated by the determination signal generation circuit and detecting the VISS signal; a capstan for running the magnetic tape; and a cap for detecting the rotation speed of the capstan. A stud FG detection circuit, and the capstan FG detection circuit, when the rotation speed of the capstan exceeds a predetermined value,
A threshold level varying circuit for controlling the threshold level in the ISS signal discriminating signal generating circuit, so that even if the control signal amplifying circuit section has poor reproducibility of the control signal waveform, the correct VI
It is possible to create an SS discrimination signal, and
SS detection can be performed.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram showing the configuration of a magnetic recording / reproducing apparatus according to the present embodiment, and FIGS. 3 and 4 are waveform diagrams. In FIG. 1, reference numeral 11 denotes a magnetic tape, 12 denotes a control head for recording and reproducing a control signal recorded in the longitudinal direction of the magnetic tape 11, and 13 denotes a control signal amplifier for amplifying a control signal from the control head 12. The circuit 14 receives the control signal amplified by the control signal amplifier circuit 13 and
A VISS determination signal generation circuit for generating a VISS determination signal required to determine whether the signal is a normal signal or a normal signal;
The VISS detection circuit 16 measures the duty of the VISS determination signal generated by the ISS determination signal generation circuit 14 and determines whether the signal is a VISS signal or a normal signal. The VISS detection circuit 16 varies the threshold level in the VISS determination signal generation circuit 14. A threshold level variable circuit for controlling, a capstan 17 for running the magnetic tape 11 and a capstan FG detecting circuit 18 for detecting the rotation speed of the capstan 17 by FG.

The operation of the magnetic recording / reproducing apparatus of the present embodiment configured as described above will be described below.

The control signal recorded in the longitudinal direction of the magnetic tape 11 is reproduced by the control head 12.
The reproduced control signal is amplified by the control signal amplifying circuit 13 and input to the VISS determination signal creating circuit 14. In VISS determination signal generating circuit 14, a control signal as shown in FIG. 3 (a) to be input, to create a VISS discrimination signal as shown in Figure based on the threshold level V _t1 3 (b). The created VISS discrimination signal is VI
The duty is input to the SS detection circuit 15 and its duty is measured to determine whether it is a VISS signal or a normal signal.

Here, the rotation speed of the capstan 17 is detected by a capstan FG detection circuit 18, and when the rotation speed exceeds a predetermined value, the threshold level variable circuit 16
The ISS determination signal generation circuit 14 is controlled so as to vary the threshold level. In other words, when the vehicle travels at a high speed such that the rotation speed of the capstan 17 exceeds a predetermined value, FIG.
As shown in (a), the waveform reproducibility of the control signal may be deteriorated.
When input to the SS determination signal generation circuit 14, the threshold level variable circuit 16
Is controlled so as to increase the threshold level Vt1 at _Vt2 to a higher level _Vt2 than _Vt1 . In VISS discrimination signal generating circuit 14, VISS based on the threshold level V _t2
By creating the signal, a correct VISS signal can be created as shown in FIG. 4C, and the VISS detection circuit 15 can detect the correct VISS signal.

[0015]

As described above, according to the present invention, when the waveform reproducibility of the control signal is poor, the VISS determination signal can be correctly generated by changing the threshold level of the VISS determination signal generation circuit. This provides an excellent effect that VISS detection becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional magnetic recording / reproducing apparatus.

FIG. 3A is a waveform diagram of an input control signal. FIG. 3B is a waveform diagram of a VISS signal created based on the control signal.

4A is a waveform diagram of a control signal having poor waveform reproducibility; FIG. 4B is a waveform diagram of a VISS signal generated by a VISS signal generation circuit in a conventional magnetic recording / reproducing apparatus; Waveform diagram of VISS signal created by magnetic recording / reproducing device

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Magnetic tape 12 Control head 13 Control signal amplifier circuit 14 VISS discrimination signal creation circuit 15 VISS detection circuit 16 Threshold level variable circuit 17 Capstan 18 Capstan FG detection circuit

Claims (1)

[Claims] 1. A control signal amplifying circuit for amplifying a control signal recorded in a longitudinal direction of a magnetic tape, and a VIS based on a predetermined threshold level of a control signal output from the control signal amplifying circuit.
A VISS determination signal generation circuit for generating an S determination signal, and a VISS determination signal generated by the VISS determination signal generation circuit.
A capstan for running the magnetic tape, a capstan FG detecting circuit for detecting the number of revolutions of the capstan, and a capstan for detecting the VISS signal by measuring the duty of the discrimination signal; FG
A magnetic recording / reproducing apparatus comprising: a threshold level variable circuit for controlling a threshold level in the VISS signal determination signal generation circuit when the rotation speed of the capstan exceeds a predetermined value in a detection circuit.