JPH067416B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus such as a video tape recorder, and more particularly to a magnetic recording / reproducing apparatus for reproducing information at a recording speed of, for example, 1.5 times. .

[Prior Art and Its Problems] In a magnetic image recording / reproducing apparatus, a so-called video tape recorder (VTR), in reproducing an already recorded image signal, the traveling speed of the magnetic tape is set higher than that in the normal reproducing speed. There is a so-called video search function for viewing images in a short time. In order to understand the contents of the audio recorded at the same time as the video reproduction, the tape speed should be reduced to about 1.5 to 2 times. The problems of the conventional reproducing device when the running speed of the magnetic tape is 1.5 times the speed will be described below.

FIG. 2 shows a control block diagram in a conventional tape running system.

Reference numeral 1 is a magnetic tape, 2 is a capstan motor for feeding the magnetic tape 1, and 2a is a capstan shaft of the capstan motor. G is a frequency generator for detecting the rotation speed of the capstan motor 2,
The detection signal of the frequency generator G is amplified by the amplifier 3 and then frequency / voltage converted by the frequency discriminator 9,
It is input to one input terminal of the summing amplifier 4.

The control signal recorded for phase control on the magnetic tape 1 is read by the control head 5, amplified by the amplifier 6, and then input to the phase comparator 7. The phase comparator 7 compares the control signal with the reference signal, and the comparison result is input as a voltage value to the other input terminal of the summing amplifier 5. As a result, the addition amplifier 4 performs addition calculation of the speed signal and the phase signal, and drives the capstan motor 2 based on the calculated value.

As described above, by providing the speed control unit that processes the signal from the frequency generator FG and the phase control unit that processes the signal from the control head 5, the running of the magnetic tape 1 is speed-controlled and at the same time the rotary head moves. The phase relationship of the magnetic tape 1 is controlled with respect to the rotational position so that synchronization is maintained.

However, for reproduction at 1.5 times speed, capstan motor 2
When only the rotational speed of is increased 1.5 times, the track pattern recorded on the magnetic tape 1 and the locus due to the movement of the reproducing head cannot be synchronized, and naturally, they do not match, and the azimuth of the head during recording and the azimuth of the head during reproducing Due to the coincidence and non-coincidence, a track pattern that should be reproduced is not reproduced and a track pattern that should not be reproduced is reproduced and appears as noise on the reproduction screen.

In order to solve this problem, conventionally, noiseless reproduction was performed by displacing the rotary head up and down in accordance with the running of the magnetic tape, but this method requires a rotation speed and a rotation attitude that require accurate rotation. There was a structural problem because the head was mechanically moved up and down.

[Object of the Invention] The present invention has been made to eliminate the above-mentioned problems, and enables noiseless reproduction by controlling the phase of the running of the magnetic tape and the rotation of the rotary head even at the time of reproducing at 1.5 times speed. It is an object of the present invention to provide a magnetic recording / reproducing device having the above structure.

[Structure of the Invention] The present invention provides a tape feeding means (2) for running a magnetic tape.
And a frequency generator (G) that detects the tape running speed
And, based on the detection frequency from the frequency generator (G),
A speed control section for sending a predetermined speed signal to the tape feeding means (2), a reproducing means for reproducing a recording signal on the magnetic tape, and a phase detecting means for detecting the control signal recorded on the magnetic tape ( 5) and based on the frequency of the control signal detected by the phase detecting means (5), a predetermined phase signal is sent to the tape feeding means (2) in order to control the phase between the magnetic tape and the reproducing means. In a magnetic recording / reproducing apparatus equipped with a phase control unit, the frequency detected by the frequency generator (G) is divided by 2/3 to divide the detected frequency in order to reproduce at a tape running speed 1.5 times that of recording. A frequency divider (8) and a frequency divider (10) for dividing the frequency of the control signal detected by the phase detection means (5) into 1/3 times.

[Embodiment] FIG. 1 shows a control block diagram of a tape running system in an embodiment of the present invention, in which the same parts as those in the conventional example are designated by the same reference numerals.

In the speed controller, the signal amplified by the amplifier 3 is input to the frequency divider 8. The frequency divider 8 outputs the signal from the amplifier 3 as it is at the time of normal reproduction, but when a 1.5 × speed signal is inputted to the frequency divider 8, the frequency of the input signal is doubled and then divided by 3 minutes. Output after lap. The output signal of the frequency divider 8 is input to one input terminal of the summing amplifier 4 via the frequency discriminator 9. The frequency discriminator 9 discriminates the frequency of the input signal. If the frequency divider 3 does not divide the frequency of the signal, the input signal is output as it is.
A predetermined signal for double speed is output.

In the phase controller, the output signal of the amplifier 6 is the frequency divider 1
Input to 0. This frequency divider 10 outputs the signal from the amplifier 6 as it is during normal reproduction, but when a 1.5 × speed signal is input to this frequency divider 10, the reproduction head and the recording track pattern on the magnetic tape 1 are separated. In order to maintain the positional relationship, the control signal, which is track information obtained from the control head 5, is divided into three. The output signal of the frequency divider 10 is input to the other one input terminal of the summing amplifier 4 via the phase comparator 7.

In the above-mentioned control block diagram, in the case of normal reproduction, the frequency dividers 8 and 10 and the frequency discriminator 9 output the input signal as they are, as described above. Therefore, the circuit configuration shown in FIG. It is the same, and normal reproduction is performed as described in the conventional example.

Next, the operation at the time of reproduction at 1.5 times speed will be described.

When the 1.5 × speed signal is input to the frequency divider 8 and the frequency divider 10, the frequency corresponding to the rotation speed from the frequency generator FG is converted into 2/3 by the frequency divider 8 as described above. Since this reduced signal frequency is input to the addition amplifier 4, the addition amplifier 4 outputs a drive signal for multiplying the rotation speed of the capstan motor 2 by 3/2 (= 1.5). In this way, the speed controller feeds the magnetic tape 1 at 1.5 times the normal reproduction speed.

In the phase controller, the control signal divided by 3 is input to the phase comparator 7, so that the phase relationship between the reproducing head and the recording track pattern on the magnetic tape 1 is maintained at 1.5 times speed.

As a result, the phase relationship between the recording track pattern on the magnetic tape 1 and the locus pattern of the reproducing head is maintained even when the reproducing speed of the magnetic tape 1 is increased by 1.5 times, and noiseless reproduction at 1.5 times speed is possible.

[Effects of the Invention] As described above, the present invention not only controls the running speed of the magnetic tape at the time of reproducing at 1.5 times speed, but also controls the positional relationship between the recording track pattern on the magnetic tape and the locus of the reproducing head, that is, the phase control. As a result, noiseless playback is possible even when playing back at 1.5 times speed.

[Brief description of drawings]

FIG. 1 is a control block diagram of a magnetic tape running system according to an embodiment of the present invention, and FIG. 2 is a control block diagram of a conventional magnetic tape running system. 1 ... Magnetic tape, 2 ... Capstan motor, 3, 6
...... Amplifier, 4 …… Adding amplifier, 5 …… Control head, 7 …… Phase comparator, 8,10 …… Divider, 9 ……
Frequency discriminator.

Claims (1)

[Claims] 1. A tape feeding means for running a magnetic tape.
(2) and a frequency generator that detects the tape running speed (
G) and a speed control section for sending a predetermined speed signal to the tape feeding means (2) based on the detection frequency from the frequency generator (G), and a reproducing means for reproducing the recording signal on the magnetic tape. , Phase detection means (5) for detecting a control signal recorded on the magnetic tape, and phase control of the magnetic tape and the reproduction means based on the frequency of the control signal detected by the phase detection means (5) Therefore, in a magnetic recording / reproducing apparatus equipped with a phase control unit for transmitting a predetermined phase signal to the tape feeding means (2), a frequency generator (in order to reproduce at a tape running speed 1.5 times that at the time of recording) G) which divides the detection frequency by 2/3 times, and a frequency divider (10) which divides the frequency of the control signal detected by the phase detecting means (5) by 1/3 times. ) And a magnetic recording / reproducing apparatus.