JPH04286482A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate the need for a complicated circuit for applying special reproduction to a digital video signal. CONSTITUTION:One field of a digital recording signal generated based on a digital video signal subject to A/D conversion by a 1st conversion means 1 is recorded on a surface layer of a magnetic medium 7 while being divided into plural track by a 1st magnetic head 6. On the other hand, an FM modulation means 12 frequency-modulates a low frequency carrier based on an analog video signal to generate an FM modulation recording signal. The said FM modulation recording signal is recorded to a deep layer of the magnetic medium 7 by a 2nd magnetic head 30 in precedence over the 1st magnetic head 6. Switching means 5, 31, 32 select the circuit so that a reproduction output is obtained from the 1st magnetic head 6 at normal reproduction and from the 2nd magnetic head 30 at the special reproduction.

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 recording/reproducing digital video signals onto/from a magnetic medium.

0002

2. Description of the Related Art A main part of a conventional magnetic recording/reproducing apparatus for recording/reproducing digital video signals is schematically shown in FIG. When recording video information, the analog video signal is
The converter 100 converts the signal into a digital video signal. This digital video signal is encoded by an encoder 101, modulated by a modulator 102, amplified by a recording amplifier 103, and then sent to a changeover switch 104 connected to the terminal R11 side.
It is then supplied to the rotating head 105.

On the other hand, during normal reproduction of video information,
The playback output of the rotary head 105 is transmitted to the playback amplifier 110 via the changeover switch 104 connected to the terminal P11 side.
is supplied to The amplified output of the reproduction amplifier 110 is
The signal passes through a changeover switch 111 connected to the terminal N11 side, is demodulated by a demodulator 112, decoded by a decoder 113, and converted into an analog video signal by a D/A converter 114 and output.

[0004] Also, during special playback of video information, the changeover switch 111 is connected to the terminal S11 side, and the playback output of the rotary head 105 is supplied to the special playback processing circuit 115. Note that in order to display the entire image during special playback, it is also possible to store video information from which noise has been removed in a memory, read the video information from the memory, and play it back.

FIG. 4 shows a recording/reproducing scanning pattern of the rotary head 105 on the magnetic tape 106. The illustrated symbol Tn represents a recording track. in this case,
By rotating the rotary head 105 at high speed, one field of video signal is divided into four tracks and recorded.
The rotary head 105 is made smaller.

[0006]

By the way, during special reproduction, by changing the running speed of the magnetic tape 106, the scanning pattern of the rotary head 105 becomes, for example, Ts, which traverses a plurality of tracks Tn.

In this case, the special reproduction processing circuit 115 to which the reproduction output of the rotary head 105 is supplied has a complicated configuration because it performs processing such as signal rearrangement. Particularly, when a digital signal is subjected to compression processing, the signal processing in the reproduction system becomes even more complicated, so there is a problem that the configuration of the special reproduction processing circuit 115 becomes even more complicated.

[0008]Furthermore, the above-mentioned special playback using the memory has the problem that it is difficult to obtain a stable image.

[0009]

[Means for Solving the Problems] In order to solve the above problems, a magnetic recording and reproducing device according to the invention of claim 1 includes a first converting means for converting an analog video signal into a digital video signal and a first converting means for converting an analog video signal into a digital video signal. A second conversion means for converting into an analog video signal is provided, and one field of a digital recording signal generated by performing predetermined signal processing on the digital video signal is divided into a plurality of tracks and recorded.

Furthermore, the magnetic recording and reproducing apparatus according to the first aspect of the invention is characterized in that it includes at least the following means. Namely, (1) a first magnetic head (for example, a first rotary head) that records the digital recording signal on the surface of a magnetic medium (for example, a magnetic tape) by dividing it into a plurality of tracks; and (2) a low-frequency carrier based on the analog video signal. FM modulates the FM signal to generate an FM modulated recording signal.
modulating means; (2) a second magnetic head (for example, a second rotary head) that records the FM modulated recording signal in the deep layer of the magnetic medium before the first magnetic head; (2) normal reproduction at the same frame rate as during recording; Sometimes, switching means (for example, a changeover switch) is used to perform switching so that a playback output is obtained from the first magnetic head, and a playback output is obtained from the second magnetic head during special playback at a frame rate different from that during recording. ).

In order to solve the above-mentioned problem, the magnetic recording/reproducing apparatus according to the second aspect of the present invention is further characterized in that it further includes at least the following means. Namely, (1) a field memory in which a digital video signal corresponding to one field of video information is written; (2) during the special playback, the reproduction output of the second magnetic head supplied via the switching means is FM-demodulated, and an analog video signal is generated; FM demodulation means for outputting a signal; (2) a control section for controlling the write bit rate and read bit rate of the digital video signal to the field memory during recording and special playback;

Furthermore, the magnetic recording and reproducing apparatus according to the second aspect of the invention is characterized by the following configuration. That is, (1) during recording, an analog video signal corresponding to one field of video information via the field memory and the second conversion means is supplied to the FM modulation means; (2) during special playback; The digital video signal passed through the FM demodulation means and the first conversion means is written into the field memory; (3) the control section sets the write bit rate of the field memory to a first bit rate during recording; The read bit rate is set to a second bit rate that is higher than the first bit rate, while during special playback, the write bit rate of the field memory is set to the second bit rate, and the read bit rate is set to the second bit rate. control to set the bit rate to 1 bit rate.

[0013]

According to the structure of claim 1, the digital video signal obtained by A/D-converting the analog video signal by the first converting means is subjected to predetermined signal processing and becomes a digital recording signal. The digital recording signal is divided into a plurality of tracks and recorded on the surface layer of the magnetic medium by the first magnetic head.

The FM modulation means FM modulates the low frequency carrier based on the analog video signal to generate an FM modulated recording signal. Therefore, since the frequency band of the FM modulated recording signal is lower than that of the digital recording signal, the second magnetic head records the FM modulation recording signal deep into the magnetic medium. Note that since the recording operation by the second magnetic head precedes the recording operation by the first magnetic head, the surface layer portion recorded by the second magnetic head is rewritten by the recording by the first magnetic head.

[0015] The switching means is arranged so that during normal playback at the same frame rate as during recording, a playback output is obtained from the first magnetic head, and during special playback at a frame rate different from that during recording, the second magnetic head is activated. Switching is performed so that playback output can be obtained from.

As a result of the above, during special reproduction, the FM modulated recording signal recorded in the deep part of the magnetic medium is read out by the second magnetic head and reproduced as an analog video signal, so that the digital video signal is A complicated circuit configuration for playback becomes unnecessary.

[0017] Furthermore, according to the structure of claim 2, at the time of recording,
An analog video signal corresponding to one field of video information via the field memory and the second conversion means is supplied to the FM modulation means. However, the read bit rate from the field memory is set to a second bit rate that is higher than the first bit rate, which is the write bit rate, by the control operation of the control section.

As a result, the FM modulated recording signal corresponding to one field of video information is recorded as one wide track by the second magnetic head, whereas the FM modulation recording signal corresponding to one field of video information is recorded as one wide track. The digital recording signal is recorded as a plurality of narrow tracks by the first magnetic head.

During the special reproduction, the reproduction output of the second magnetic head supplied via the switching means is FM demodulated by the FM demodulation means to reproduce an analog video signal. This analog video signal is A/D converted by the first conversion means to become a digital video signal, which is written into the field memory at the second bit rate by the control operation of the control section. The read bit rate from the field memory during special playback is set to the first bit rate by the control operation of the control section.

As a result of the above, during special playback, the field memory stores one field of video information based on the FM modulation recording signal recorded in the deep part of the magnetic medium. , the entire image is reproduced stably.

[0021]

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

As shown in FIG. 1, the magnetic recording/reproducing apparatus according to the present invention includes a first rotary head 6 as a first magnetic head.
and a second rotating head 30 as a second magnetic head. The first rotary head 6 converts the analog video signal into a digital video signal, and records the generated digital recording signal through predetermined signal processing on the surface layer of the magnetic tape 7 having a magnetic medium. The second rotary head 30 sends an FM modulated recording signal that is low frequency modulated based on the analog video signal to the deep part of the magnetic tape 7.
Recording is performed prior to the first rotating head 6. Note that the running direction of the magnetic tape 7 is indicated by an arrow A1 in the figure.

First, the configuration of the recording system of the magnetic recording/reproducing apparatus will be explained. The recording system connected to the first rotary head 6 includes an A/D converter 1, an A/D converter 1, and an analog video signal input side.
An encoder 2, a modulator 3, a recording amplifier 4, a terminal R1, and a changeover switch 5 as switching means are connected in this order.

On the other hand, the recording system connected to the second rotary head 30 connects the analog video signal input side to the A/D
converter 1, field memory 10, D/A converter 11,
An FM modulator 12, a recording amplifier 13, a terminal R2, and a changeover switch 31 as a switching means are connected in this order. Also, field memory 1
The write/read bit rate of 0 is controlled by the control unit 20.

The A/D converter 1 is supplied with an analog video signal and functions as a first conversion means for converting the analog video signal into a digital video signal. The encoder 2 encodes the digital video signal according to the number of recording bits. The modulator 3 performs modulation processing optimal for recording and generates a digital recording signal.

In the recording system including the second rotary head 30, the field memory 10 stores and holds one field's worth of video information. The D/A converter 11 functions as a second conversion means for converting a digital video signal into an analog video signal. The above FM modulator 12
functions as an FM modulation means that frequency modulates the low frequency carrier based on the analog video signal output from the D/A converter 11.

Next, the reproduction system connected to the first rotary head 6 includes, from the first rotary head 6 side, a changeover switch 5, a terminal P1, a changeover switch 32 as a switching means, a terminal N1, a reproduction amplifier 33, Demodulator 34
, a decoder 35, and a D/A converter 36 as a second conversion means are connected in order. The reproduction system connected to the first rotary head 6 is used for normal reproduction in which reproduction is performed at the same frame rate as the frame rate during recording.

On the other hand, the reproduction system connected to the second rotary head 30 includes, from the second rotary head 30 side, the changeover switch 31, the terminal P2, and the changeover switch 32.
, terminal S1, reproduction amplifier 40, FM demodulator 41, first
An A/D converter 42 as a conversion means, a field memory 43, and the D/A converter 36 are connected in this order. The reproduction system connected to the second rotary head 30 is used for special reproduction in which reproduction is performed at a frame rate different from the frame rate during recording.

The demodulator 34 demodulates the digital recording signal. The decoder 35 converts the code of the demodulated digital recording signal and outputs the original digital video signal. The output of the decoder 35 is supplied to a D/A converter 36, and an analog video signal is output.

In the reproduction system including the second rotary head 30, the FM demodulator 41 demodulates the FM modulated recording signal that has been appropriately amplified via the reproduction amplifier 40 and outputs an analog video signal. . The field memory 43 also stores and holds one field of video information output from the A/D converter 42, similarly to the field memory 10. The write/read bit rate of the field memory 43 is also controlled by the control unit 20.

In the above configuration, the analog video signal is converted into a digital video signal by the A/D converter 1 and supplied to the encoder 2, and one field worth of digital video signal is written into the field memory 10. . The digital video signal supplied to the encoder 2 is sent to the modulator 3
, the recording amplifier 4, the terminal R1, the changeover switch 5, and the first rotary head 6, and are recorded on the surface layer of the magnetic tape 7.

On the other hand, the digital video signal written in the field memory 10 is read out at a bit rate that is, for example, four times the writing bit rate, by the control operation of the control unit 20, and is then FM modulated via the D/A converter 11. is supplied to the vessel 12. In the FM modulator 12, the low frequency carrier is D/
FM modulation is performed based on the analog video signal output from the A converter 11, and the FM modulated recording signal is sent to the recording amplifier 1.
3, terminal R2, and the changeover switch 31 to the second rotary head 30. Second rotating head 30
records the video information delayed by one field on the magnetic tape 7 in advance of the first rotary head 6.

FIG. 3 shows how the magnetic tape 7 composed of the magnetic layer 7a and the tape base layer 7b is magnetized by the first rotary head 6 and the second rotary head 30. However, the magnetic tape 7 is running along arrow A2 in the figure. Since the frequency of the FM modulated recording signal supplied to the second rotary head 30 is lower than that of the digital recording signal supplied to the first rotary head 6, the magnetic layer 7a is magnetized to its deep layer by the FM modulated recording signal (
(Indicated by B in the figure). On the other hand, since the above digital recording signal has a high frequency, it is recorded in a superimposed manner on the surface layer portion of the magnetic layer 7a (indicated by C in the figure). As a result, the surface layer portion previously recorded by the second rotary head 30 is rewritten by the first rotary head 6.

Furthermore, since the digital video signal written in the field memory 10 is read out at a bit rate four times the writing bit rate, the first rotating head 6
The second rotary head 30 rotates four times to record one field of video information in segments, whereas the second rotary head 30 records one field of video information in one revolution. This is equivalent to compressing the time axis of the FM modulation signal supplied to the second rotary head 30 to 1/4. In other words, the second rotary head 30 does not perform recording in the second to fourth rotations of the first rotary head 6 in one field recording.

In this way, as shown in FIG. 2, one field of digital recording signals generated based on the digital video signal is recorded by four tracks T6, and one field of FM modulation signals is recorded by one field. Recorded by book track T30. Note that the width of the track T30 is set equal to or slightly narrower than four times the width of the track T6.

Next, when the video information is normally reproduced from the magnetic tape 7, the digital recording signal recorded on the surface layer of the magnetic layer 7a is read by the first rotary head 6, and the changeover switch 5, terminal P1, The signal is supplied to the reproduction amplifier 33 via the changeover switch 32 and the terminal N1. The digital recording signal is moderately amplified by a reproduction amplifier 33, and then sent to a demodulator 34, a decoder 35, and a D/A
The signal is converted into an analog video signal via a converter 36 and output. At this time, the changeover switch 31 is connected to terminals R2 and P2.
It is not connected to either and is turned off.

When video information is specially reproduced from the magnetic tape 7, the changeover switch 5 is turned OFF and the changeover switch 31 is connected to the terminal P2. magnetic layer 7
The FM modulation recording signal recorded in the deep part of a is read by the second rotary head 30, and the changeover switch 31
, terminal P2, changeover switch 32, and terminal S1
The signal is supplied to the reproduction amplifier 40 via. The FM modulated recording signal is moderately amplified by the reproduction amplifier 40, and then sent to the FM demodulator 4.
1 and is demodulated to become an analog video signal.

[0038] This analog video signal is sent to the A/D converter 4.
2, the digital video signal is converted into a digital video signal, and one field of the digital video signal is written into the field memory 43.

Contrary to the case of the field memory 10, the digital video signal is read from the field memory 43 at a bit rate that is 1/4 of the write bit rate by the control operation of the control unit 20. One field of digital video signals read from the field memory 43 is converted into an analog video signal by the D/A converter 36.

[0040] Therefore, by successively reading one field of video information stored in the field memory 43, special reproduction can be performed and a stable overall image can also be obtained. This eliminates the need for a complicated circuit configuration required for special reproduction of digital video signals.

[0041]

As described above, the magnetic recording and reproducing device according to the invention of claim 1 includes a first magnetic head that records the digital recording signal on the surface portion of the magnetic medium by dividing it into a plurality of tracks, and the analog FM modulation means for FM modulating a low frequency carrier based on a video signal to generate an FM modulated recording signal; and a second FM modulating means for recording the FM modulated recording signal in a deep portion of the magnetic medium prior to the first magnetic head. During normal playback using the magnetic head and the same frame rate as during recording, a playback output is obtained from the first magnetic head.
During special playback with a frame rate different from that during recording,
The magnetic head is configured to include switching means for switching so that a reproduced output can be obtained from the second magnetic head.

Therefore, during special reproduction, the FM modulation recording signal recorded in the deep part of the magnetic medium is read out by the second magnetic head and reproduced as an analog video signal, so that the digital video signal can be specially reproduced. This has the effect of eliminating the need for a complicated circuit configuration.

As described above, the magnetic recording and reproducing apparatus according to the invention of claim 2 includes, in addition to the structure of claim 1, a field memory in which a digital video signal corresponding to one field of video information is written, and the special During reproduction, an F demodulates the reproduction output of the second magnetic head supplied via the switching means to generate an analog video signal.
M demodulation means; and a control section for controlling a write bit rate and a read bit rate of the digital video signal to the field memory during recording and special playback; An analog video signal corresponding to one field of video information is supplied to the FM modulation means, and during special playback, a digital video signal that has passed through the FM demodulation means and the first conversion means is stored in the field memory. The control unit sets the write bit rate of the field memory to a first level during recording.
bit rate, and the read bit rate is set to a second bit rate that is higher than the first bit rate. During special playback, the write bit rate of the field memory is set to the second bit rate, and the read bit rate is set to the second bit rate, which is higher than the first bit rate. This is a configuration in which control is performed so that the bit rate is set to the first bit rate.

Therefore, during special playback, one field of video information based on the FM modulation recording signal recorded in the deep part of the magnetic medium is stored in the field memory, so even during special playback, This has the effect of stably reproducing the entire image.

[Brief explanation of the drawing]

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

FIG. 2 is an explanatory diagram showing a scanning pattern by a first rotary head and a second rotary head on a magnetic tape.

FIG. 3 is an explanatory diagram showing surface recording by a first rotary head and deep recording by a second rotary head on a magnetic tape.

FIG. 4 is an explanatory diagram showing a recording/reproducing scanning pattern and a special reproduction scanning pattern on a magnetic tape by a rotary head included in a conventional magnetic recording/reproducing apparatus.

FIG. 5 is a block diagram showing the configuration of main parts of a conventional magnetic recording and reproducing device.

[Explanation of symbols]

1 A/D converter (first conversion means) 5 Changeover switch (switching means) 6 First rotating head (first magnetic head) 7 Magnetic tape (magnetic medium) 10 Field memory 11 D/A converter (second conversion means) means) 12
FM modulator (FM modulation means) 30 Second rotating head (second magnetic head) 31 Changeover switch (switching means) 32 Changeover switch (
switching means) 36 D/A converter (second conversion means) 41 FM demodulator (FM demodulation means) 42
A/D converter (first conversion means) 43 Field memory

Claims (2)

[Claims] 1. A first converting means for converting an analog video signal into a digital video signal and a second converting means for converting the digital video signal into an analog video signal, the digital video signal being generated by performing predetermined signal processing on the digital video signal. A magnetic recording and reproducing apparatus that records one field of a digital recording signal by dividing it into a plurality of tracks, the first magnetic head recording the digital recording signal by dividing it into a plurality of tracks on the surface portion of a magnetic medium, and the analogue FM modulation means for FM modulating a low frequency carrier based on a video signal to generate an FM modulated recording signal; and a second FM modulating means for recording the FM modulated recording signal in a deep portion of the magnetic medium prior to the first magnetic head. During normal playback using the magnetic head and the same frame rate as during recording, playback output is obtained from the first magnetic head, and during special playback using a frame rate different from that during recording, playback output is obtained from the second magnetic head. A magnetic recording/reproducing device characterized in that it is provided with a switching means for performing switching so as to obtain a magnetic recording/reproducing device. 2. A field memory in which a digital video signal corresponding to one field of video information is written; and FM demodulation of the playback output of the second magnetic head supplied via the switching means during the special playback; FM demodulation means for outputting an analog video signal; and a control section for controlling a write bit rate and a read bit rate of the digital video signal to the field memory during recording and special playback; The analog video signal corresponding to one field of video information passed through the second conversion means is supplied to the FM modulation means, and during special playback, the analog video signal corresponding to one field of video information is converted into a digital video signal passed through the FM demodulation means and the first conversion means. is written in the field memory, and the control unit sets the write bit rate of the field memory to a first bit rate and sets the read bit rate to a second bit rate higher than the first bit rate during recording.
while setting the bit rate to the second bit rate, during special playback, the write bit rate of the field memory is set to the second bit rate, and the read bit rate is controlled to be set to the first bit rate. Item 1. The magnetic recording and reproducing device according to item 1.