JP2548246B2 - Video signal digital magnetic recording / reproducing apparatus - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for video signals.

2. Description of the Related Art Various techniques and devices for recording or storing video signals have been put into practical use, and among them, a magnetic recording / reproducing device (hereinafter referred to as "VTR") for video signals using a magnetic tape as a recording medium is for home use. Is beginning to spread rapidly.

The present invention relates to this VTR. Therefore, a conventional example of a VTR will be described below with reference to the drawings.

FIG. 4 is a recording pattern diagram of a magnetic tape in a conventional VTR. In the figure, 9 is a magnetic tape, 34 to 35 are helical scan tracks, and 37 and 38 are linear tracks. (39 will be described later.) In a home VTR, etc., the former is subjected to FM modulation after being separated into the luminance component and the color component in the video signal, and the latter is frequency-converted to the low frequency and recorded on the same track. are doing. By the way, since the frequency bandwidth of the video signal is wide, the helical scan method is adopted, and a licked track is formed on the magnetic tape 9. In this way, the video signal is sequentially recorded on the helical scan tracks 34 to 36 after being subjected to the predetermined processing.

On the other hand, an audio signal or the like is recorded on the linear tracks 37 and 38 because the frequency bandwidth is narrow.

By the way, in the above-mentioned household VTR, signal processing is performed in an analog manner, and magnetic recording is performed in an analog manner.
On the other hand, a method for digitally processing a video signal and an audio signal and further digitally recording them on a magnetic tape has been actively researched, mainly for improving reproduction image quality. The former is called an analog VTR (hereinafter referred to as "AVTR") and the latter is called a digital VTR (hereinafter referred to as "DVTR"). In the DVTR, it is not necessary to record the video signal and the audio signal on separate tracks as in the AVTR, and it is more convenient to record them on the same track in terms of Mushiko signal processing. Therefore, the video signal data and the audio signal data are often multiplexed in some form and recorded on the same helical scan track.

In the recording pattern diagram shown in FIG. 4, in the case of DVTR, if both the video signal and the audio signal are recorded on the helical scan track, the linear tracks 37 and 38 are recorded.
Need not necessarily be provided.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, in the recording / reproducing of the helical scan system, the recording / reproducing characteristics at both ends (both edges in the width direction) of the magnetic tape 9 are usually deteriorated. There is no choice but to use a little space. Recording and reproducing in a space is not preferable in terms of effective use of the recording medium, and the tape consumption increases, which is uneconomical.

The present invention solves the above-mentioned problems and, in addition, can realize high-quality image reproduction at the time of high-speed special reproduction, and obtain an extremely large effect.

SUMMARY OF THE INVENTION Therefore, according to the present invention, a recording side processing means for performing a predetermined digital processing on a video signal, a rotary head for recording the output of the recording side processing means on a magnetic tape, and a recording side processing means. Side rate converting means for rate converting the output of the recording side, a fixed head for recording the output of the recording side rate converting means on a linear track on the magnetic tape, a rotary head and a fixed head for taking out the information recorded on the magnetic tape. A reproduction side rate conversion means for rate conversion of the output of the fixed head, a switch for selecting one of the output of the reproduction side rate conversion means and the output of the rotary head, and a switch for selecting the output of this switch. The above-mentioned switch is provided with a reproducing side processing means for performing digital processing, and the above-mentioned switch converts the reproducing side rate to the rotary head side during normal reproduction during high speed special reproduction. It should be closed on the means side.

With the above-described structure, during high-speed special reproduction, the information from the linear track is restored to the normal rate by the reproduction side rate conversion means, and the complete one-frame data is restored to the reproduction side processing means. Passed. Further, since the output of the reproduction side rate conversion means is updated every relatively short time, a high quality screen can be reproduced even in high speed special reproduction, and the recorded contents can be monitored.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is a video signal input terminal, 2 is an analog-to-digital converter (hereinafter referred to as "A / D", also referred to as "A / D" in FIG. 1), and 3 is recording side processing. Device, 4 a modulator, 5 a recording side rate converter, 6 a modulator, 7 a rotary head, 8
Is a fixed head, 9 is a magnetic tape, 10 is a rotating head, 11 is a fixed head, 12 and 13 are demodulators, 14 is a rate converter on the reproducing side, 15 is a switch, 16 is a processor on the reproducing side, and 17 is digital / analog. A converter (hereinafter referred to as "D / A", also referred to as "D / A" in FIG. 1), and 18 is a video signal output terminal. The video signal to be recorded is supplied to the A / D 2 via the input terminal 1. The analog video signal is digitized by A / D 2 and applied to the recording side processor 3. The recording-side processor 3 performs processing such as band compression and error correction coding, and guides it to the modulator 4 and the recording-side rate converter 5. The modulator 4 digitally modulates the output of the recording side processor 3 in a predetermined manner and records it on the magnetic tape 9 via the rotary head 7. On the other hand, the recording-side rate converter 5 expands the output of the recording-side processing unit 3 on the time axis to reduce the data rate, and applies it to the modulator 6. Modulator 6
Digitally modulates the output of the recording side rate converter 5 in a predetermined manner and records it on the magnetic tape 9 via the fixed head 8.

On the other hand, at the time of reproduction, the information recorded on the magnetic tape 9 is taken out via the rotary head 10 and the fixed head 11 and input to the demodulators 12 and 13, respectively. (Actually, a head amplifier, an equalizer, a clock regenerator, etc. are required between the magnetic head and the demodulator, but these are omitted here to simplify the description.) The signal read via the rotary head 10 is demodulated by the demodulator 12 and applied to one terminal of the switch 15. On the other hand, the signal read out through the fixed head 11 is demodulated by the demodulator 13 and reproduced on the reproducing side rate converter.
Applied to 14. The reproducing side rate converter 14 performs a process reverse to that of the recording side rate converter 5, converts the data applied at a low speed into a normal data rate and data format, and supplies it to the other input terminal of the switch 15. The switch 15 selects either the output of the demodulator 12 or the reproduction side rate converter 14 and inputs it to the reproduction side processor 16. Playback side processor
16 mainly performs processing reverse to that of the recording side processor 3, performs error correction decoding, band compression reverse conversion, error correction, etc., restores to analog video signal at D / A 17, and outputs. A reproduced video signal is transmitted via the terminal 18.

At the time of recording, the video signal is recorded on the magnetic tape 9 via the A / D 2, the recording side processor 3, the modulator 4 and the rotary head 7. On the other hand, the recording side rate converter 5 takes in data of a predetermined interval and a predetermined number of data from the output data string of the recording side processor 3 to reduce the data rate of the data, and the magnetic data is transmitted via the modulator 6 and the fixed head 8. Record on tape 9. Here, the recording side rate converter 5 takes in one frame of data (that is, one frame for every 300 frames) every 10 seconds and lowers the rate to 1/300. The rotary head 7 forms the helical scan tracks 34 to 36 of FIG. 4, and the fixed head 8 forms the linear track 38 of FIG.

On the other hand, during reproduction, the rotary head 10 and the fixed head 11 trace and reproduce the helical scan tracks 34 to 36 and the linear track 38 of FIG. 4, respectively. Therefore, in normal reproduction, the switch 15 is closed on the demodulator 12 side, and a normal reproduction image is obtained via the output terminal 18. Also, the playback side rate converter
From 14, new data for one frame is output every 10 seconds.

2 is a timing chart of FIG. 1, 19 is a frame timing, 20 is an output data string of the recording side processor 3, 21 is an nth frame, 22 is an (n + 300) th frame, 2
3 and 24 are output data strings of the recording side rate converter 5, and 25 is an output data string of the reproducing side rate converter 14. Of the output data string 20 of the recording side processor 3, the data in the period of the nth frame 21 is taken in by the recording side rate converter 5 and the time axis is extended by about 300 times like 23 (the data rate is 1
/ 300). Further, the data of the (n + 300) th frame 22 is also taken in by the recording side rate converter 5 and the time axis is expanded 300 times like 24. On the other hand, these time-axis expanded (rate-converted) data strings 23 and 24 are recorded on the linear track 38 of FIG. At the time of reproduction, the data strings corresponding to the data strings 23 and 24 are read out, and the reproduction side rate converter 14 compresses the time axis to 1/300 (the data rate is increased 300 times) to become the data string 25. . The data string 25 (the one corresponding to 24 is not shown) has a period of just one frame, and has been restored to the original time axis.
In this way, the reproduction side rate converter 14 outputs the data updated every 300 frames.

By the way, during normal reproduction, the rotary head 10 uses the magnetic tape 9
Correctly trace the top helical tracks 34-36. However, when the magnetic tape 9 is run at a speed different from the normal reproduction (hereinafter referred to as "special reproduction"). The rotary head 10 crosses the helical scan tracks 34 to 36 recorded as shown in FIG. 4 and traces as shown by a broken line 39. If this happens, it will not be possible to obtain a normal playback image. However, in the case of the present invention, since data is recorded one after another on the linear track 38 as still images, even if the magnetic tape 9 is run at high speed, the switch 15
Close the playback side rate converter 14 side to the linear track.
Fast forward by using the playback data from 38,
You can reproduce a high-quality screen even with high-speed post feed, and you can check the recorded contents even with high-speed tape feed.

In the embodiment of the present invention, it is assumed that the rate is reduced to 1/300 and recording is performed on the linear track 38. Therefore, when the tape feeding speed is increased by 30 times, one new still image is output per second, At 60 times, still images of recorded contents are output at a rate of 2 sheets per second.

As described above, according to the present invention, the end portion of the magnetic tape 9 is effectively used as a linear track, and at the same time, a high quality reproduced image can be obtained by special reproduction.

By the way, since the relative speed difference between the tape heads of the helical scan tracks 34 to 36 and the linear track 38 is large, it takes a relatively long time to update the still image obtained in special reproduction in which the magnetic tape feeding speed is not so fast. Will be required. Also, in slow or relatively slow special playback, playback of a moving image is required. Therefore, another embodiment of the present invention that meets this demand will be described below with reference to the drawings.

FIG. 3 is a cross-sectional view showing a state of a rotary head portion for helical scanning and its periphery. In the figure, 26
Is a fixed cylinder, 27 is a rotary cylinder, 28 and 29 are electrostrictive elements, 30 and 31 are rotary heads, and arrows 32 and 37 are deviations. Since 26 and 27 are well known, their description is omitted. The electrostrictive elements 28 and 29 are, for example, two materials that are mechanically strained when a voltage is applied, and since the amounts of the strains are different, the tips of the electrostrictive elements 28 and 29 are vertical as shown by arrows 32 and 33. It shifts to. The rotary heads 30 and 31 attached to the ends of the electrostrictive elements 28 and 29 are displaced as indicated by arrows 32 or 33.

With such a structure, the rotary head
Can be traced correctly. That is,
In special reproduction, the trace is normally traced as shown by the broken line 39 in FIG. 4, but since the rotary heads 30 and 31 can be displaced in the direction perpendicular to the head scanning direction as shown in FIG. 3, even in special reproduction,
The helical tracks 34 to 36 can be scanned correctly. In this way, a high quality reproduced image can be obtained.

By the way, there are various restrictions on such complementary colors by the electrostrictive element, and it cannot be applied to high-speed tape feeding and can be applied only to relatively low tape feeding. Therefore, even in special reproduction, a high-quality reproduced image can be obtained by tracing the track with an electrostrictive element in low-speed tape feeding and extracting data from the linear track shown in FIG. 1 in high-speed tape feeding. In addition, the medium speed tape feed will allow you to play a relatively high quality video, though not completely, due to the correction.
In this way, high-quality images can be obtained by any special reproduction from low-speed tape feeding to high-speed tape feeding, and as a matter of course, recorded contents can be confirmed with extremely high-quality images even in high-speed search.

The present invention has been described with the embodiments. By the way, the change ratio in the recording rate converter 5 is assumed to be 300, but the change ratio is not limited to this, and the linear track 37 or both may be used without being limited to the linear track 38. Further, although the rotary heads 7 and 10 are described as forming the helical scan tracks 34 to 36, the present invention can be applied not only to the helical scan but also to other scans such as transversal scan. Also, demodulator 1
The two and thirteen are not necessarily required for the two systems, and they can be shared and placed after the switch 15.

EFFECTS OF THE INVENTION As is clear from the above description, the present invention makes it possible to effectively use a magnetic tape and at the same time obtain a high-quality reproduced image during special reproduction. DV that enables high-quality playback even with tape feed
It provides TR.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory view showing timings and data strings of each part of FIG. 1, and FIG. 3 is a state of a head cylinder part using an electrostrictive element. FIG. 4 is a tape pattern diagram showing the state of tracks in the conventional system and the present invention. 3 ... Recording side processor, 4, 6 ... Modulator, 5 ... Recording side rate converter, 7, 10 ... Rotating head, 8, 11 ... Fixed head, 12, 13 ... Demodulator, 14 ...... Playback side rate converter, 15
...... Switch, 16 …… Reproduction side processor, 28,29 …… Electrostrictive element.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuro Shigesato 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP 63-179679 (JP, A) JP 63- 7084 (JP, A)

Claims (2)

(57) [Claims] 1. A recording side processing means for subjecting a video signal to be recorded to a predetermined digital signal processing, a first modulating means for digitally modulating the output of the recording side means, and an output of the first modulating means. A rotary head for recording on magnetic tape,
Recording side rate converting means for rate converting the output of the recording side processing means, second modulating means for digitally modulating the output of the recording side rate converting means, and output of the second modulating means on the magnetic tape. A fixed head for recording, the above or other rotary head for taking out the information recorded on this magnetic tape, a first demodulating means for digitally demodulating the output of this rotary head, and the above recorded on the magnetic tape. The above or other fixed head for retrieving information
Second demodulating means for digitally demodulating the output of the fixed head, reproducing side rate converting means for rate converting the output of the second demodulating means, output of the reproducing side rate converting means and the first demodulating means. A switch for selecting any one of the outputs and a reproduction side processing means for performing a predetermined digital signal processing on the output of the switch to restore reproduced video data.
The digital magnetic recording / reproducing apparatus for a video signal, wherein the output of the demodulating means is selected and the output of the reproducing side rate converting means is selected during high speed special reproduction. 2. A rotary head used at least during reproduction is attached via an electrostrictive element, and during low speed special reproduction, the voltage applied to the electrostrictive element is controlled to trace on a recorded track. A digital magnetic recording / reproducing apparatus for a video signal according to claim 1, wherein