JP2609731B2 - 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 and reproducing apparatus for performing insert editing using a multi-channel magnetic head mounted on a rotating drum.

[Conventional technology]

Insert editing is editing in which a part of a previously recorded track is rewritten with another signal, and is one of the effective functions in a VTR (video tape recorder) in which video and audio signals are recorded and reproduced. The servo system of so-called 8 mm video using an 8 mm tape employs a 4-frequency pilot system.
There is one shown in No. 60-79550.

In a conventional recording / reproducing apparatus employing a pilot signal system, at least one magnetic head is additionally provided in addition to two normal recording / reproducing magnetic heads installed at a position of 180.degree. Also at the time of editing, the track pattern is made continuous and uniform.

 Hereinafter, description will be made with reference to the drawings.

FIG. 4 is a layout view of a magnetic head installed on a rotating drum, and two normal recording / reproducing magnetic heads 21 and 22 are
The magnetic heads 21 and 2
Another pair of magnetic heads 23 and 24 on the same plane as 2
Are installed at positions rotated by 90 ° with respect to the magnetic heads 21 and 22, respectively.

FIG. 5 shows a circuit configuration of a rotary head type VTR to which the magnetic recording / reproducing apparatus according to the present invention is applied. Fifth
In the figure, reference numeral 19 denotes a first circulating frequency generator which generates a signal of four frequencies for each field in a cycle of four fields by a head switching pulse input to an input terminal 1.

These four frequencies are, for example, NTSC (National Telel)
When recording a video signal of the vision system committee) system, f ₁ = f _osc / 58, f ₂ = f _osc / 50, f ₃ = f as f _osc −378fh (fh: frequency of the horizontal synchronization signal). _osc / 36, and f ₄ =
Choose like f _osc / 40. The output of this frequency generator 19 is
The superimposed signal is superimposed on the modulated video signal input to the input terminal 3 by the addition circuit 2, and the superimposed signal is passed through the recording amplifier 4, the switch 5, and the rotary transformer 20, and
2 to record on the magnetic tape. The recording pattern is recorded by circulating F1 to F4 as shown in FIG.

 Next, normal reproduction will be described.

Reference numeral 8 denotes a regenerative amplifier. The output of the regenerative amplifier is filtered by a low-pass filter (hereinafter abbreviated as LPF) 9 to remove a video signal component and extract a pilot signal component. A pilot signal component extracted by the LPF 9 and an output of a circulating frequency generator 19 for sequentially generating frequencies f ₁ , f ₂ , f ₃ , f ₄ for each field according to a head switching pulse are mixed with a mixer 10.
Is input to The output of the mixer 10 is passed through a first band-pass filter (hereinafter, abbreviated as BPF) 11 and a second BPF 12, whereby the signal frequency of the peripheral force of the circulating frequency generator 2 and the pilot signal of the LPF 9 are output. A difference frequency signal component from the frequency of the component is obtained.

By the way, in the case of NTSC video signal, f _osc 5.95MHZ
z, f ₁ , f ₂ , f ₃ and f ₄ are f ₁ 102 KHz, f ₂ 119 KH
z, f ₃ 165 KHz and f ₄ 149 KHz. Thus, f ₂ −f ₁
f ₃ −f ₄ 16.5 KHz and f ₄ −f ₁ f ₃ −f ₂ 46.5 KHz.
Therefore, the pass band of the first BPF 11 is set to around 16.5 KHz,
Suppose that the pass band of BPF12 is selected near 46.5 KHz. Sixth
As shown in the figure, when the magnetic head 21 is tracking the track of F1, a signal having an amplitude proportional to the magnitude of the pilot signal (frequency f ₂ ) component of the track of F2 is the first signal.
A signal having an amplitude proportional to the magnitude of the pilot signal (frequency f ₄ ) component of the track of F4 is obtained from the second BPF 12.

The outputs of the first BPF 11 and the second BPF 12 are envelope-detected by the second detector 14 of the first detector 13, and the outputs of the first and second detectors 13 and 14 are subtracted. 6, a voltage level corresponding to the amount of left or right displacement of the magnetic head 21 from the track center in FIG. 6 is obtained as the output of the subtractor 15.

The and 6 Figure recording _{pattern, f 1, f 2, f} 3 and, as is apparent from the frequency of f _4, and when the magnetic head 21 is tracking the F1 or F3 in Figure 6, F2 or F4
And the polarity of the output of the subtractor 15 with respect to the displacement of the magnetic head 21 from the track center is reversed. Therefore, if the output of the subtracter 15 and the signal obtained by inverting the output of the subtractor 15 by the inverting amplifier 16 are selected by switching the head switching pulse period with the switch 17,
An output voltage proportional to the amount of displacement of the magnetic head 21 from the track center is obtained from the output terminal 18. By feeding back the signal obtained from the output terminal 18 to a capstan motor (not shown), good tracking can be obtained.

Next, the configuration and operation at the time of insert editing will be described.

Reference numeral 25 denotes a switch for supplying the reproduction output of the magnetic head 23 or the magnetic head 24 to the reproduction amplifier 8 at the time of insert editing. 26 is a delay circuit for shifting the phase of the head switching pulse by 90 °, and 27 is a vapor delay circuit. f ₁ described above on the basis of the output of 26, f _2, a second circulation frequency generator for generating a frequency of f ₃ and f _4, 28 is a mixer the output of the second circulation frequency generator 27 during insert editing A switch 29 for supplying the signal to the first detector 13 or the second detector 14 for each field based on the output of the delay circuit 26 is provided.
Is a switch for selecting the output of the amplifier 30 and supplying the output to the amplifier 30, and 31 is a switch for supplying the output of the amplifier 30 to the output terminal 18 during insert editing.

At the time of insert editing, the output of the first circulating frequency generator 19 is superimposed on the video signal derived from the input terminal 3, and this signal is recorded by the recording amplifier 4, switch 5 and rotary transformer 20.
Through the magnetic tape TP by applying to the magnetic heads 21 and 22
Record on top. On the other hand, the magnetic head 23 and the magnetic head 24
To reproduce the signal on the magnetic tape TP, and supplies this signal to the reproduction amplifier 8 through the rotary transformer 20 and the switch 25.

At the start of signal recording in insert editing, first, the tape running control in the normal reproduction described above is performed, and after entering synchronous control, the mode is switched to the insert editing mode at a desired recording start point. At this time, the positional relationship between the recording pattern on the magnetic tape TP and each of the magnetic heads 21 to 24 is, for example, as shown in FIG. The magnetic head 21 is located at the leading end of the F1 track, and the magnetic head 22 is located at the trailing end of the F4 track. Accordingly, since the magnetic head 23 has the positional relationship as shown in FIG. 4, it is located at the center of the track and on the boundary between the F4 track and the F1 track. The delay circuit 26 shifts the phase of the head switching pulse by 90 °, and the switching position of the magnetic head 23 or the magnetic head 24 is
Alternatively, head switching is performed such that the magnetic head 22 is at the same position as the head switching position in the tape width direction. Furthermore the delay circuit 26 is f _1, f _2, sequentially generates signals of frequencies f ₃ or f ₄ in a predetermined order from the second circulating frequency generator 27 at its output. Now in the magnetic head position shown in FIG. 6, f ₄
Is generated by the second circulating frequency generator 27. At this time, the first circulating frequency generator 19 outputs f ₄
Switching to generate a frequency f ₁ from the frequency of the.

In the position of the magnetic head 23 shown in FIG. 6, the signal reproduced from the magnetic head 23, a pilot signal component and the head width of the frequency of the magnitude of f ₁ corresponding to the half of the head width 1 / 2 includes frequency components of f ₄ of the corresponding magnitude. The two pilot components are extracted by the LPF 9 and added to the mixer 10. On the other hand, since the occurrence frequency of f ₄ of the second circulation frequency generator 27, a signal having an amplitude difference frequency components between f ₁ is corresponding to half of the head width is obtained from the second BPF12 Can be When the magnetic head 24 is located on the boundary between the F1 track and the F2 track in FIG. 6, that is, the magnetic head 21 is located above the tape width of the F1 track, but the magnetic head 22 is located above the tape width of the track F2. in the case of there downward, since the second circulation frequency generator 27 is generating a signal of a frequency of f _1, head difference frequency components between f ₁ and f ₂ are riding F2 track A signal having an amplitude proportional to the width is obtained from the first BPF 11.

When the frequency of the second circulating frequency generator 27 is controlled by the signal obtained by shifting the head switching pulse obtained by the delay circuit 26 by 90 ° in phase, the magnetic head 23
The second BPF12 is located on the boundary between the F4 and F1 tracks or on the boundary between the F2 and F3 tracks.
A signal having an amplitude proportional to the amount of displacement from the boundary line of the magnetic head 23 is obtained from the above, and when the magnetic head 24 is on the boundary line between the F1 track and the F2 track or on the boundary line between the F3 track and the F4 track, From the first BPF 11, a signal having an amplitude proportional to the amount of displacement from the boundary of the magnetic head 24 is obtained.

Therefore, if the output of the delay circuit 26 is used to select the output of the first detector 13 or the output of the second detector 14 with the switch 29, the output is proportional to the amount of displacement from the boundary of the magnetic head 23 or 24. Voltage can be obtained. This means that the voltage value is equivalently shown in proportion to the amount of displacement of the magnetic head 21 or 22 from the track. This signal is supplied to an amplifier 30 to give an appropriate DC offset and an amplifier gain to the output terminal 18 through a switch 31.

When the output of the second circulation frequency generator 27 is fixed to the frequency of f _1, shows the output voltage of the output terminal 18 with respect to the position deviation amount of the tape longitudinal direction of the magnetic head 24 in FIG. 7. In Figure 7, the gradually integrates the output voltage in the tape longitudinal direction becomes V _1. The output voltage at the desired tracking position is
V ₀ , and the lock range when the control loop is formed is obviously limited. Therefore, if synchronization is performed in the normal playback mode before the start of the insert editing, even if the mode shifts to the insert editing mode, the control ability for the small signal component is sufficient and the control can be performed without any trouble. Therefore, according to the above, a uniform and continuous recording pattern can be obtained even during insert editing.

[Problems to be solved by the invention]

Since the conventional magnetic recording / reproducing apparatus is configured as described above, it is necessary to add at least one magnetic head in addition to the normal recording / reproducing head, which increases the cost and makes it difficult to reduce the size of the drum. There were problems such as.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a digital recording / reproducing apparatus capable of insert editing in which a track pattern is continuous and uniform without adding a magnetic head. I do.

[Means for solving the problem]

A magnetic recording / reproducing apparatus according to the present invention is an apparatus for recording or reproducing N tracks in one cycle of information, wherein a multi-channel magnetic head is used to reproduce a signal for at least one track and N tracks in one cycle. A minute signal is recorded, a magnetic tape running control is performed during reproduction, and N tracks are recorded during recording.

[Action]

According to the present invention, by performing reproduction and recording in one cycle using a multi-channel magnetic head, it is possible to control the running speed of the magnetic tape from at least the reproduction signal of one track, and to record the N tracks on the track. It can be performed so that the pattern is continuous and uniform.

〔Example〕

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

In FIG. 1, 51 is an input terminal for a modulated video / audio signal, 52 is an input terminal for a pulse synchronized with the rotation of the drum,
53 is a servo pilot signal generation circuit, 54 is an addition circuit, 55 is a recording amplifier, 56 is a recording / reproduction switch,
57 is a rotating drum, 58 and 59 are 2 with different azimuth angles
A channel magnetic head, 60 is a tracking actuator for vertically moving the magnetic heads 58, 59 on oblique tracks, 61 is a magnetic tape wound 180 ° around a rotating drum 57, 62 is a capstan motor, 63 is a reproduction amplifier, 64 Is a tracking error signal detection circuit, 65 is a capstan servo circuit, and 66 is a tracking servo circuit.

Next, the operation will be described with reference to the track pattern diagram of FIG. 2 and the time chart of FIG.

In this embodiment, one cycle period corresponds to one image frame (NTSC
1/30 second in the system) and recording on two tracks. The video / audio signal input from the input terminal 51 is triggered by the drum rotation pulse (60 Hz in this case) shown in FIG. Occur. However, in FIG. 3D, the portion written as W is a recording period, and since the magnetic heads 58 and 59 are two-channel heads as described later, F1, F2 and F3, F4 are provided for each W. Occur alternately. The pilot signal is superimposed on the video / audio signal by the adder circuit 54, and then passes through a recording amplifier 55, a changeover switch 56, a rotary transformer (not shown), and magnetic heads 58, 59.
Is recorded on the magnetic tape 61. The magnetic head shown in FIG.
Is a movable head. During normal recording, recording is performed with the position of the tracking actuator 60 fixed. The tracks recorded in this manner are shown in the track pattern diagram of FIG. FIG. 2A is a schematic view thereof, and FIG. 2B is an enlarged view during recording. In FIG. 2 (b), the head
I and II correspond to the magnetic heads 58 and 59, respectively, have different azimuth angles, and the head width is slightly wider than the track width.

Now, a description will be given of a case where the magnetic tape recorded in this manner is insert-edited. First, two rotations are performed in one cycle period (here, one frame). That is, the drum rotation pulse in FIG. 3A is set to 60 Hz, and at least one track is reproduced in the first rotation. Here, reproduction servo is applied using the reproduction signal of the magnetic head 59. The reproduction signal from the magnetic head 59 is input to the tracking error signal detection circuit 64 via the changeover switch 56 and the reproduction amplifier 63. The tracking error signal is obtained by the method described in the conventional example,
Capstan motor 62 by capstan servo circuit 65
To control the tape feed speed. On the other hand, the tracking servo circuit 66 drives the tracking actuator via a slip ring (not shown) in accordance with a signal as shown in FIG.

The second rotation is recorded on two tracks as follows. Since the tape feed is performed in the playback mode, the tape is running at a constant speed. In the tracking servo circuit 66, if the recording is performed by generating the driving voltage generated one rotation before as shown in FIG. 3 (c), the track pattern is continuous and uniform, and the track bend is the same as the reproduced track. .

FIG. 2C shows the state of the magnetic head and the track pattern for recording and reproduction. Until insert editing is performed, the vehicle runs in the reproduction mode, so that the pattern recorded by the head I is reproduced by the head II. In this case, the azimuth angle is different, but since the pilot signal is a low frequency signal,
A sufficient signal level can be secured. In the insert part the second
As shown in FIG. 3C, recording is performed by the heads I and II shaded in the second rotation of the previous cycle, and reproduction is performed in the first rotation of the next cycle. In this case, the recording pattern width of the head I in the area reproduced by the head II is slightly reduced, but there is no effect since the pilot signal has a low frequency. Also, a part of the signal reproduced by the head II on the head I side reproduces the recording pattern after the insert editing, but since the pattern before the insert editing is reproduced from the part opposite to the head I side, No problem. It should be noted that a magnetic head having three or more channels can fully reproduce a pattern before insert editing.

In the above embodiment, a magnetic head of 2 channels × 1 is used, but this may be any channel head.

Further, in the above-described embodiment, the case where N tracks are scanned twice during one cycle has been described. However, it is sufficient that the number of scans is two or more, and one of them may be assigned to recording.

Further, in the above embodiment, the case where the movable head is used has been described, but a fixed head may be used as long as it does not follow the track bending.

〔The invention's effect〕

As described above, according to the present invention, at least one track of a signal is reproduced and N tracks of a signal are recorded during one cycle period. There is an effect that an insert edit that can be continuously and uniformly performed can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram mainly showing servo signals of a magnetic recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a track pattern diagram thereof, FIG. 3 is a time chart diagram of servo signals, and FIG. FIG. 5 is a block diagram of the conventional magnetic recording / reproducing apparatus with a focus on servo signals, FIG. 6 is a diagram showing the track pattern and the state of the magnetic head, FIG. Figure is an output voltage diagram for the magnetic tape longitudinal position deviation when the fixed signal frequency of the circulating frequency generator to f _1. 57 is a rotating drum, 58 and 59 are magnetic heads, 60 is a tracking actuator, 64 is a tracking error signal detection circuit, 65 is a capstan servo circuit, and 66 is a tracking servo circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A multi-channel magnetic head on which information such as a video or audio signal is mounted on a rotating drum.
In a helical scan type magnetic recording / reproducing apparatus that performs recording / reproducing of N tracks (N: integer) during a cycle period, a running control of a magnetic tape is performed by a tracking error signal obtained by reproducing at least one track within one cycle period. , And then perform recording on N tracks.