JPH06267010A - Rotary head type recording/reproduction device - Google Patents

Abstract

PURPOSE:To obtain a digital signal recording/reproduction device which can record compressed digital video signal as it is and can extend the recording time of one tape by four hours or longer. CONSTITUTION:At least four magnetic heads 101-104 with a narrow track width are provided on a rotary cylinder. Then, two modes are provided, namely a first mode for running a recording medium at a first feed rate for recording and reproduction and a second mode for recording and reproducing by running it at a second feed rate which is 2/3 times faster than the first feed rate. Further, the rotary cylinder is rotated at 0.54X10<6>divided by Mdivided by NX30 per minute, where the natural number M is the number of data within one packet in an interframe signal and N packets of signals are transmitted within one field. Therefore, by setting M=148 and N=60 and using the second mode, signal can be recorded for 240 minutes, namely four hours, using a 160-minute tape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal recording / reproducing apparatus for recording / reproducing a signal using a rotary head,
In particular, the present invention relates to an apparatus for recording / reproducing a compressed digital video signal.

[0002]

2. Description of the Related Art As a high-definition screen television, the Television Society of Japan, Vol. 46, No. 3, (1992), pages 276 to 28.
As described on page 3, a digital broadcasting system for compressing and transmitting a digital video signal has been considered.

FIG. 2 shows a method of compressing a digital video signal. Reference numerals 21 and 22 represent one frame of the television screen. The video signal is compressed by compressing all the image information in the frame for every 9th frame as indicated by diagonal lines, and for the other frames, only the difference information is obtained by using the prediction from the data of the previous or subsequent frame. The amount of transmission is reduced by performing compression. In the following description, the former is referred to as an intra frame and the latter is referred to as an inter frame, and the packets are configured and transmitted.

When recording a video signal sent by such a digital broadcast, if the compressed digital video signal is recorded as it is, the recording capacity is small and efficient recording can be performed.

The transmission rate of the compressed video signal is 17.28 Mbps for the intra frame and 4.32 Mbps for the inter frame, and the total transmission rate is 20 Mbps (bit / s).
It is considered to be possible to record using a home VTR, for example, a conventional standard VTR.

However, in order to record a video signal having a transmission rate of 20 Mbps, it is necessary to record on a tape at a frequency of about 20 MHz, and the conventional VTR currently recorded at a frequency of 7 to 8 MHz is used as it is. When used, it cannot be recorded.

In view of this, the number of recording heads for recording video signals is increased to four or more as compared with the current number of two, and the recording frequency is increased by simultaneously recording on a large number of tracks in one scan. It is possible to reduce the number, and it is possible to record the digital video signal as it is.

[0008]

However, if the number of heads is increased, it becomes necessary to increase the tape feeding speed or reduce the track width.

When the tape feeding speed is increased, the recording time becomes short, and it becomes impossible to record on a tape for 4 hours or more, for example.

Further, if the track width is narrowed, it becomes difficult to obtain a good reproduction signal during reproduction, which makes practical use impossible.

When a conventional standard VTR is used,
Since the transmission rate of the digital video signal and the frame frequency of the VTR are asynchronous, it is impossible to record the video signal without excess or deficiency.

An object of the present invention is to provide a rotary head type recording / reproducing apparatus capable of directly recording a compressed digital video signal by using a conventional standard VTR and capable of recording a single tape for 4 hours or more. To provide.

[0013]

SUMMARY OF THE INVENTION The above object is to achieve a narrow track width on a rotating cylinder in a conventional standard VTR.
A first mode in which at least four magnetic heads are provided and the recording medium is run at a first feed speed for recording / reproducing; and a second mode in which the recording medium is 2/3 times the first feed speed. There are provided two kinds of modes, that is, a second mode in which the vehicle is driven at a feeding speed of 5 to record and reproduce, and the rotating cylinder is used with natural numbers M and N, and 0.54 × 10 ⁶ ÷ M ÷ N × min. It can be achieved by rotating at 30.

Here, the natural number M is the number of data in one packet in the interframe signal, and it is assumed that N packets are transmitted in one field.

[0015]

[Function] The tape feed speed is set to the standard speed, and four tapes are used.
When recording is performed using a narrow track width magnetic head in the double mode, the recording area on the tape is ⅔ of the normal recording area.
Therefore, the tape feeding speed can be increased to 2/3 times, and the recording time can be extended to 3/2 times (1.5 times). As a result, when a 160-minute tape is used, recording can be performed for 240 minutes, that is, 4 hours.

In addition, the rotary cylinder has an interframe transmission rate of 4.32 MHz (0.54 MHz ×).
By rotating in synchronization with 8), it is possible to record a digital video signal of N packets × M bytes in one field without excess or deficiency.

[0017]

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

FIG. 1 shows the structure of a rotary head type recording / reproducing apparatus of the present invention, and 5 is a recording / reproducing apparatus part using a conventional standard VTR.

Reference numeral 1 is an antenna, 4 is a receiver for receiving the transmitted digital video signal, 6 is a receiving circuit for receiving the signal, 7 is a demodulating circuit for demodulating the digital signal from the received signal, and 8 is a transmitting circuit. An error correction circuit that corrects an error that sometimes occurs, 9 is a video processing circuit that expands a compressed video signal, 10 is an audio processing circuit that processes an audio signal transmitted together with the video signal, 11 is a switching circuit, 1
An interface circuit 2 inputs and outputs signals to and from the recording / reproducing apparatus. Reference numeral 5 is a recording / reproducing device for recording the transmitted digital video signal, 13 is an interface circuit for inputting / outputting a signal to / from a receiving device, 14 is a recording processing circuit for generating a recording signal from the input digital video signal, Reference numeral 15 is a reproduction processing circuit for demodulating a digital signal from a reproduction signal, 17 is a rotating cylinder, 18 is a magnetic tape,
Reference numeral 19 is a servo circuit for controlling the feeding speed of the magnetic tape 18 and the rotational speed of the rotary cylinder 17.

Further, 101 to 104 are magnetic heads, which are magnetic heads 1 for video in a conventional standard VTR.
The magnetic heads 102 and 104 are added to 01 and 103. Here, 3 in the conventional standard VTR
A recording head having a track width of 19 μm, which is a double mode (hereinafter referred to as EP mode) track width, is used.
Since the audio signal is included in the output signal from the interface circuit 12, it is not necessary to separately record the video signal and the audio signal.
The magnetic head 4 for audio in the conventional VTR of the conventional standard may be replaced with a head for video 4.

Reference numeral 105 designates a selection circuit for selecting whether the reference signal given to the servo circuit 19 is from the reproduction processing circuit 14 or the recording processing circuit 15, and is switched depending on the recording mode or the reproduction mode.

Reference numeral 106 denotes a mode selection input terminal for selecting a tape feed speed mode during recording.

In the receiving device 4, at the time of normal reception, the switching circuit 11 selects the output of the demodulation circuit 7, and the video signal and the audio signal are output from the output terminals 2 and 3, and at the same time, via the interface circuit 12. The compressed digital video signal is output to the recording / reproducing device 5. When reproducing the recorded signal, the switching circuit 11 selects the output of the interface circuit 12, and the recording / reproducing device 5
The signal reproduced in step 3 is input to the error correction circuit 8. The error correction circuit 8 performs error correction using the error correction code added to the received digital video signal. After that, the video processing circuit 9 and the audio processing circuit 10 perform processing such as expansion and output from the output terminals 2 and 3.

By recording the signal before error correction,
The error correction circuit 8 can correct an error generated at the time of transmission, and at the same time, can detect and correct an uncorrectable error generated in the recording / reproducing device 5.
For an uncorrectable error generated in the recording / reproducing apparatus 5, a flag indicating the error may be received from the recording / reproducing apparatus 5 together with the reproduction signal. Of course, the output of the error correction circuit 8 may be recorded in the recording / reproducing device 5.

In the error correction device 5, at the time of recording, the recording processing circuit 14 adds a recording error correction code, a synchronizing signal, etc. to the digital video signal input from the receiving device 4 to generate a recording signal, and the rotating cylinder It records on the magnetic tape 18 by 17. During reproduction, the signal reproduced by the rotary cylinder 17 is input to the reproduction processing circuit 15,
The digital signals are demodulated by correcting errors that occurred during recording and reproduction. Then, it outputs to the receiving circuit 4.

FIG. 3 shows an example of a signal output from the interface circuit 12 to the recording / reproducing apparatus 5. The interface circuit 12 separates the digital video signal into a high priority signal and a low priority signal and outputs them.
The data 62 and the data 64 have a packet configuration. The packet is composed of a high priority data packet (H packet) and a low priority packet (L packet). The transmission rates of the H packet data and the L packet data are 4.32 Mbps and 17.28, respectively.
Mbps, and the ratio of data amount is 1: 4.
Then, the H synchronization signal 61 and the L synchronization signal 63 are added to each of the H packet data and the L packet data.

The H packet is, for example, intra frame data which can be expanded only by the data of the frame or a control signal of high importance, and the L packet is, for example,
It is composed of inter-frame data and audio data that are expanded using the data of the previous or subsequent frame.

The recording / reproducing apparatus 5 may separate the high priority and the low priority. Further, the H packet and the L packet may be output separately.

FIG. 4 shows the structure of the packets 62 and 64, which consists of 148 bytes. Reference numeral 65 denotes a header, which is composed of a data type, a frame number, position information within the frame, and the like. Reference numeral 66 is data, which is composed of a digital video signal and an error correction code added during transmission. The transmission frequency of the H packet is 3.65 kHz (4.
32 MHz ÷ 8 ÷ 148), and the transmission frequency of the L packet is 14.60 kHz (17.28 MHz ÷ 8 ÷ 14).
8).

When the conventional recording apparatus having only two heads records both the H packet data 62 and the L packet data 64 having the above-mentioned data amount, 20 MH
Since a recording frequency of about z is required, as shown in FIG. 1, it is assumed that two heads are mounted on the rotary cylinder 18 so as to face each other by 180 degrees and simultaneous recording on two tracks is performed by one scanning.

When the number of heads is increased, it is necessary to increase the tape feeding speed or narrow the track width. However, if the track width is narrower than the current one, good reproducing characteristics cannot be obtained. It is necessary to use the track width of 19 μm in the EP mode in the conventional standard VTR.

In this case, since the number of heads is doubled, it is necessary to double the tape feeding speed.
Therefore, if the tape feeding speed is set to 22.24 mm / sec, which is twice as fast as the EP mode in the conventional VTR, it is possible to perform good recording and reproduction. Hereinafter, the recording / reproducing mode at the tape feeding speed of 22.24 mm / sec is referred to as a long time mode.

FIG. 5 shows a recording pattern on the magnetic tape 18 in the long time mode.

Reference numerals 54 to 57 respectively indicate one track. For example, the track 54 is simultaneously recorded by the magnetic head 101, the track 55 is simultaneously recorded by the magnetic head 102, the track 56 is simultaneously recorded by the magnetic head 103, and the track 57 is simultaneously recorded by the magnetic head 104. Will be recorded. In the long time mode, as shown in the figure, recording is performed without gaps between the tracks.

In this long time mode, the tape feeding speed is 2/3 times as high as that in the standard mode in the conventional standard. Therefore, when a 160-minute tape is used, recording / reproducing for 4 hours becomes possible.

FIG. 6 shows a magnetic tape 1 at a standard speed of 33.36 mm / sec, which is the same as the conventional standard.
8 is a recording pattern. In this case, since the same track width as in the long time mode is used and the tape feeding speed is 1.5 times faster, as shown in the figure, a gap is generated between the tracks and crosstalk from the adjacent tracks is reduced.
The recording / reproducing characteristics are better than those in the long time mode.

By the way, in order to record all the H packet data 62 and the L packet data 64 without excess or deficiency, a field cycle is constituted by a constant number of input H packets, and the rotary cylinder 17 is driven at a frequency synchronized with this field cycle. Need to rotate. In that case, it is easier to control by setting the frequency close to the television field frequency in the conventional standard.

Therefore, the input time for 50 to 70 H packets is set as a packet field cycle, and the rotary cylinder 17 is rotated at a speed twice the packet field cycle. Packet field cycle (number of H packets = N)
And the number of rotations (W: minute speed) of the rotary cylinder 17 are: W = 4.32 × 10 ⁶ ÷ (8 × 148 × 2 × N) × 60 = 0.54 × 10 ⁶ ÷ 148 ÷ N × It can be represented by 30.

Typical packet period and rotating cylinder 17
Table 1 shows the relationship between the rotational speeds (speeds per minute).

The rotational speed of the rotary cylinder in the conventional standard VTR is 1798.2 [rpm].

[0041]

[Table 1]

FIG. 7 shows the recording timing when the packet field period is 60H packet. Reference numeral 71 is a signal indicating the switching timing of the magnetic heads 101 and 103.
When 1 is L, it indicates that the magnetic head 103 is in a recording state, and is synchronized with the rotary cylinder 17. Reference numeral 72 is a reference that is given to the servo circuit 19 that controls the rotation of the rotary cylinder 18 and the like, and is a signal that is inverted every input of 60 H packets, and is generated by the recording processing circuit 15. By the servo circuit 19, the reference signal 73,
The rotation of the rotary cylinder 17 is synchronized.

Input H packet data 74 and input L
Since the ratio of the transmission rate of the packet data 75 is 1: 4, one packet field cycle is 240L packet cycle. Therefore, as a standard for one packet field period, L packet is used instead of H packet data as described above.
Packet data may be used.

Reference numeral 76 is a recording timing on the magnetic tape 18 by the magnetic heads 101 and 103 (represented by A head in the figure), and 77 is magnetic tape 18 by the magnetic heads 102 and 104 (represented by B head in the figure). The recording timing to the above is shown respectively. Here, B head 1
02 and 104 with respect to the A heads 101 and 103,
It is assumed that they are attached at a position shifted by 60 °. The magnetic tape 18 is divided into 60 blocks × 3 recording areas and recorded in units of blocks to be described later.

As shown in FIG. 7, L packet data is recorded in the first two areas of each track, and H packet data is recorded in the third area by the A heads 101 and 103. In the figure, a shaded portion 78 is a margin amble portion for absorbing the rotation jitter of the rotating cylinder 17. In addition, the third area 79 of the B heads 102 and 104 is not used.
Packet data may be recorded in multiplex.

During reproduction, the rotation of the rotary cylinder 17 is controlled by the servo reference signal 73 generated by the reproduction processing circuit 14.

FIG. 8 is a block diagram of blocks constituting each area of FIG. 81 is a sync signal consisting of 1 word, 8
2 is a 3-word ID signal including a block number indicating a block position, and 83 is 148-word packet data. Reference numeral 84 is a parity composed of 4 words for performing error detection and correction of the packet data 83. Each block consists of 156 words. When 8-10 modulation is used as the modulation method during recording, one word consists of 10 bits.

FIG. 9 shows the interleaving relationship between the input packet data and the recording data in each area consisting of 60 blocks shown in FIG. Each line in the figure shows the packet data 83 in FIG. 8, and each one represents one word.

A horizontal line 85 indicates each data of one input packet. As shown in FIG. 9, each data of one packet is distributed and recorded in all 60 blocks.
By doing so, even if a burst error occurs due to a dropout on the tape during reproduction, the error can be dispersed into a large number of packets, and the error correction circuit 8 of the receiving device 4 can be used.
Can be corrected by. Each data of the next packet is shown by the diagonal line 86.

FIG. 10 shows the configuration of the recording processing circuit 14. 123 and 129 are storage circuits, 122 and 128 are packet detection circuits, 124 and 130 are parity generation circuits, and 1
Reference numerals 25 and 131 are recording signal generation circuits. The H packet data output from the interface circuit 13 is input from the input terminal 121 to the H packet detection circuit 122, and the L packet data is output from the input terminal 127 to the L packet detection circuit 1.
28 is input. The packet detection circuits 122 and 128 detect the head of the packet from the H synchronization signal 61 and the L synchronization signal 63, and store them in the respective storage circuits 123 and 129. The parity generation circuits 124 and 130 generate the C1 parity 84 from the packet data stored in the storage circuits 123 and 129. In the recording signal generation circuit 76, the synchronization signal 31 and the ID signal 32 are added to the packet data and the C1 parity so that the block format of FIG.
After being modulated, the magnetic heads 101 and 103 are output from the output terminal 126, and the magnetic heads 102 and 1 are output from the output terminal 132.
Output to 04.

When the H-packet detection circuit 122 and the L-packet detection circuit 128 are operated independently of each other, as shown in FIG.
H packet data 74 and L packet data 75 shown in FIG.
It becomes impossible to control the phase of the packet field. Therefore, a mode signal is input from the mode input terminal 133 and, for example, during reproduction, the H packet detection circuit 122
By setting the L packet detection circuit 128 to the reset state and starting the operation from the time when the reproduction is changed to the recording, the phases of the fields of the H packet data 74 and the L packet data 75 can be synchronized.

FIG. 11 shows the structure of the reproduction processing circuit 15. 143 and 149 are storage circuits, 142 and 148 are block reproduction circuits, 144 and 150 are error correction circuits, 14
5, 151 are packet output circuits. Magnetic head 10
The reproduced signals reproduced by 1 and 103 are input to the A block reproducing circuit 142 from the input terminal 141, and the reproduced signals reproduced by the magnetic heads 102 and 104 are input to the B block reproducing circuit 148 from the input terminal 147. . The block reproduction circuits 142 and 148 detect the synchronization signal 81 and the ID signal 82, and the storage circuit 1
Store in place on 43 and 149. The error correction circuits 144 and 149 correct the error in the packet data using the C1 parity 84 stored in the storage circuits 143 and 149. At the same time, a pointer indicating an error state is generated and stored in the storage circuits 144 and 149. The packet output circuits 145 and 151 read the packet data from the storage circuits 143 and 149 and output the packet data from the output terminals 146 and 152.

The block reproduction circuits 142 and 148
The output data may be stored in the storage circuits 143 and 149 after being directly subjected to error correction by the error correction circuits 144 and 149.

When the H packet data is recorded in multiplex, first the pointer for the H packet data is read to check whether there is an uncorrectable error. If there is an uncorrectable error, the H packet data in the other area in which multiple recording is performed is read and output. Further, at the time of outputting the packet data, a pointer may be added and output so that the receiving device 4 can confirm the presence or absence of an error during recording and reproduction.

Although only the C1 parity 84 is added as an error correction code in the above description, a C2 parity may be added to form a double code. Figure 1
2 shows the structure of each track when C2 parity is added. In the figure, C2 parity 141
Are placed on both sides of the track, but they may be placed together at the beginning or the end.

[0056]

According to the present invention, it is possible to record a compressed digital video signal as it is by replacing the magnetic head and changing the rotational speed of the rotary cylinder by using a VTR of the conventional standard. it can. Also, it is possible to record for 4 hours using a 160-minute magnetic tape.

[Brief description of drawings]

FIG. 1 is a configuration of a digital signal recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a digital video signal compression method.

FIG. 3 shows a recording / reproducing device 5 from an interface circuit 12.
It is a timing diagram of the signal output to.

FIG. 4 is a configuration diagram of packets 62 and 64.

FIG. 5 is a recording pattern diagram on the magnetic tape 18 in a long time mode.

FIG. 6 is a recording pattern diagram on a magnetic tape 18 in a standard speed mode.

FIG. 7 is a timing chart showing an input timing and a recording timing of packet data.

FIG. 8 is a configuration diagram of a block of recording data.

FIG. 9 is a diagram showing interleaving with input packet data recording data.

10 is a configuration diagram of a recording processing circuit 14. FIG.

11 is a configuration diagram of a reproduction processing circuit 15. FIG.

FIG. 12 is a configuration diagram of each track when C2 parity is added.

[Explanation of symbols]

 4 ... Receiving device, 5 ... Recording / reproducing device, 12 ... Interface circuit, 13 ... Interface circuit, 14 ... Recording processing circuit, 15 ... Reproduction processing circuit, 19 ... Servo circuit, 105 ... Selection circuit, 101 ... Magnetic head, 102 ... Magnetic head, 103 ... Magnetic head, 104 ... Magnetic head, 106 ... Mode selection input terminal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiichi Saito 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture

Claims (21)

[Claims] 1. A recording / reproducing apparatus for recording / reproducing on / from a recording medium by using at least four magnetic heads on a rotary cylinder, and a first mode for recording / reproducing by traveling the recording medium at a first feeding speed. Further, there are provided two kinds of mode selection means of a second mode in which the recording medium is run at a second feed speed which is ⅔ times the first feed speed to record and reproduce. Rotating head type recording / reproducing device. 2. The first feed rate is approximately 33.4 mm /
2. The rotary head type recording / reproducing apparatus according to claim 1, wherein the second feeding speed is approximately 22.2 mm / sec. 3. The rotary head type according to claim 1, wherein the recording track width on the recording medium is the same in both the first mode and the second mode. Recording / playback device. 4. The rotary head type recording / reproducing apparatus according to claim 3, wherein the recording track width is approximately 19 μm. 5. The recording medium and the first feeding speed conform to a conventional VTR standard.
The rotary head type recording / reproducing apparatus described. 6. The first mode is used when an analog signal is recorded and reproduced on the recording medium, and the second mode is used when a digital signal is recorded and reproduced on the recording medium. The rotary head type recording / reproducing apparatus according to claim 1. 7. A recording / reproducing apparatus for recording / reproducing using a rotary head, wherein the rotation speed of the rotary head is 0.54 × 10 ⁶ ÷ M ÷ N × 30 per minute using natural numbers M and N. A rotary head type recording / reproducing device characterized in that 8. The rotary head type recording / reproducing apparatus according to claim 7, wherein the natural number M is 148. 9. The rotary head type recording / reproducing apparatus according to claim 7, wherein the natural number N is 60, and the rotation speed of the rotary head is approximately 1824.3 rotations / minute. 10. The rotary head type recording / reproducing apparatus according to claim 7, wherein the natural number N is 64, and the rotary speed of the rotary head is approximately 1710.3 rpm. 11. A recording / reproducing apparatus for recording a digital signal forming a packet by the natural number N of digital data, wherein the rotation is performed at a time for transmitting the digital signal in an amount of the natural number M × 2 packets. The rotary head type recording / reproducing apparatus according to claim 7, wherein the head rotates once. 12. The rotary head type recording / reproducing apparatus according to claim 7, 8 or 9, 9 or 10 or 11, wherein the rotary head complies with a conventional VTR standard. 13. A recording / reproducing apparatus for recording / reproducing on / from a recording medium by using at least four magnetic heads on a rotating cylinder, and a first mode for recording / reproducing by traveling the recording medium at a first feeding speed. And the recording medium is the first
Of the second mode of recording and reproducing by traveling at a second feed speed which is ⅔ times the feed speed of the rotary cylinder, and the rotation number of the rotary cylinder is a natural number M or N.
The rotary head type recording / reproducing apparatus is characterized in that: 0.54 × 10 ⁶ ÷ M ÷ N × 30. 14. The first feed rate is approximately 33.4 mm.
14. The rotary head type recording / reproducing apparatus according to claim 13, wherein the second feeding speed is approximately 22.2 mm / sec. 15. The rotary head type recording / reproducing apparatus according to claim 13 or 14, wherein a recording track width on the recording medium is approximately 19 μm. 16. The first mode is used when an analog signal is recorded and reproduced on the recording medium, and the second mode is used when a digital signal is recorded and reproduced on the recording medium. The rotary head type recording / reproducing apparatus according to claim 13. 17. The rotary head type recording / reproducing apparatus according to claim 13, wherein the natural number M is 148. 18. The rotary head type recording / reproducing apparatus according to claim 17, wherein the natural number N is 60, and the rotation speed of the rotary head is about 1824.3 rotations / minute. 19. The rotary head type recording / reproducing apparatus according to claim 17, wherein the natural number N is 64, and the rotation speed of the rotary head is about 1710.3 rotations / minute. 20. A recording / reproducing apparatus for recording a digital signal forming a packet by the natural number N of digital data, wherein the rotation is performed at a time for transmitting the digital signal in an amount of the natural number M × 2 packets. 14. The rotary head type recording / reproducing apparatus according to claim 13, wherein the head rotates once. 21. The rotary head type recording / reproducing apparatus according to claim 13, wherein the recording medium, the first feed speed, and the rotary head comply with a conventional VTR standard.