JP2699714B2 - Digital signal recording device, recording method and recording medium - Google Patents

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 suitable for high-density recording such as a digital VTR.

[0002]

2. Description of the Related Art In order to prevent deterioration in image quality due to high reproduction image quality and dubbing, a digital VTR for digitizing a video signal and an audio signal and recording the digital signal on a magnetic tape has been put into practical use. Generally, this digital VTR records data on a magnetic tape using a magnetic head mounted on a rotating cylinder. The rotation of the cylinder at this time is controlled based on a synchronization signal extracted from the video signal, for example, a field synchronization signal or a frame synchronization signal. That is, the control is such that the rotation number of the cylinder within one cycle of the reference signal is constant (= N).

[0003] Usually, a rotating cylinder is equipped with M (> 1) or more heads, and two revolutions per cylinder revolution.
M tracks (hereinafter referred to as tracks) are formed on the tape. Therefore, one frame of data is divided into 2M and recorded on the magnetic tape as one track. In this case, each of the divided data is recorded in synchronization with the reference signal based on a recording control signal having a frequency which is M times the frequency of the reference signal. That is, the recording control signal is a binary alternating signal in which one period of the reference signal is equally divided into 2M, and 1 and 0 are inverted for each equal division. At the rising and falling edges of this alternating signal, recording of each divided data starts.

[0004] With such control, data of one frame divided into 2M is recorded as 2M tracks on the tape. Digital V currently in practical use
The TR is for broadcasting, and the generation of such a recording control signal is extremely accurate, and has a sufficient margin for absorbing an error in a data recording start position on a tape due to a physical limit of mechanical accuracy. Therefore, even if editing such as normal recording and insert is performed, the already recorded data is not greatly disturbed.

[0005]

As described above, a digital VTR for broadcasting uses a very high-precision mechanism.
Also, the margin on the tape is large. Therefore, although there is no adverse effect of editing, taking a large margin reduces the effective area on the tape and the recording time, and at the same time, requires an ultra-high-precision mechanism and control signal generation circuit to reduce the size of the device. Becomes difficult and very expensive.

Although these are acceptable for broadcasting digital VTRs where performance is of the utmost importance, they are fatal issues for practical use of home digital VTRs that will become popular in the future. In addition, editing
This is a large function that makes use of the basic features of a digital VTR that does not degrade reproduction image quality, and is indispensable for a home digital VTR. Therefore, a technology that does not require a very high-precision mechanism for editing, has a small margin on a tape, and can be realized at low cost is necessary for practical use of a digital VTR for home use. However, current VTR control mechanisms are based on alternating signals for controlling the rotational frequency of the cylinder. Further, this control mechanism of the current home VTR is very simple, and it is impossible to maintain the position of data to be recorded on the track with high accuracy. Therefore, when rewriting already recorded data at the time of editing, the rewriting position cannot be specified accurately. For this reason, it is necessary to provide a very large buffer area on the track for editing.

As described above, in realizing a home digital VTR, a digital signal recording / reproducing apparatus capable of obtaining the same editing accuracy as that of a broadcast VTR with the mechanical accuracy of the current home VTR is desired. The major challenge is to develop technologies to achieve this. Conversely, a digital VTR for home use cannot be commercialized unless these problems are solved.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital signal recording / reproducing apparatus provided with the following new means for solving the above-mentioned problems indispensable for putting a home digital VTR into practical use. I do.

A digital signal recording apparatus having a recording means for recording a digital signal on a track on a tape-shaped recording medium, wherein a start for specifying an absolute position in the track of valid data or search information on the track. A start position information generating unit for forming position information on the track, wherein the start position information generating unit starts by connecting a plurality of first synchronization blocks each including a first synchronization pattern and a synchronization block number; A digital signal recording device or the like characterized by generating a position information sequence.

[0010]

According to the present invention, a small amount of information is formed on a track on a tape to detect the start position of data on the track with high accuracy. By using this information, the start position of the data on the track can be accurately specified, and high-precision editing can be performed without having to improve the mechanism accuracy.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example for realizing the present invention (FIG. 1)
2 shows a block diagram of the circuit configuration, and FIG. 2 shows a timing chart relating to the operation of FIG. In the present embodiment, first, the overall operation of FIG. 1 will be described, and then, the functions and operations of main circuit blocks constituting (FIG. 1) will be described.

First, the overall circuit operation will be described. In FIG. 1, a recording control signal is input to a control signal generation circuit 1. The control signal generation circuit 1 detects the edge of the recording control signal, generates a recording start signal for one track, and first sends the preamble pattern generation output signal (A) to the preamble generation circuit 2 at the H level. At the same time, the selection signal X is sent to the selection circuit 3, and the preamble pattern sent from the preamble generation circuit 2 is recorded on the tape as the first recording sequence of one track. In addition,
The preamble pattern is a special pattern for facilitating generation of a reproduction clock phase-synchronized with the reproduction data, and does not include special information. When the required number of preambles have been transmitted, the preamble pattern generation output signal (A) falls to L level, and instead, the start information generation signal
(B) is set to H level and sent to the start information generating circuit 4.

Along with this operation, the selection signal Y is supplied to the selection circuit 5.
And the output of the start information generation circuit 4 is sent to the modulation circuit 6 through the selection circuit 5. Further, the selection signal X is supplied to the selection circuit 3
And control is performed so that the output of the modulation circuit 6 becomes the output of the selection circuit 3. The modulation circuit 6 converts the input into a code sequence suitable for the recording / reproducing system, and also, for the type of input signal, ie, start information, for example, a synchronization pattern of 00110000000000111, and for search information, for example, a synchronization pattern of 00011000000000010, audio and video. As for information, for example, a synchronization pattern of 01100000000001101 is added to a modulation sequence corresponding to each input data and transmitted. When the specified amount of start information has been sent, the start information generation signal (B) goes low, the gap data generation signal (F) goes high instead, and the operation of the gap data generation circuit 7 is started. Generate and send data sequentially. At the same time, the selection signal X is sent to the selection circuit 3, and the output of the gap data generation circuit 7 is controlled to be the output of the selection circuit 3. As the gap data, basically, like the preamble pattern, a pattern that facilitates clock reproduction is selected, and does not include any information. When the transmission of the specified amount of gap data is completed, the gap data generation signal (F) is set to L level, and the transmission of gap data is stopped.

The area where the gap data is recorded is:
This is necessary when only the area for recording search information is rewritten. In other words, in terms of mechanism accuracy, it is impossible to completely rewrite only the already-recorded search information area, and a buffer area provided so that even if the rewrite position is slightly shifted does not affect other information. This is a gap region. At the same time that the generation of the gap data is completed, the search information generation signal (C) is set to the H level and sent to the search information generation circuit 8, and the selection signal Y is sent to the selection circuit 5 and the selection signal X is sent to the selection circuit 3. As a result, the output of the search information generation circuit 8 appears at the output of the selection circuit 3 through the modulation circuit 6. Note that this search information, Ri information der about e.g. position on the tape of the data to be recorded such as time code, the tape
This is information used for searching for information recorded in. When the specified amount of search information has been transmitted, the search information generation signal (C) is
Level and stop generating search information. At the same time, the gap data generation signal (F) is set to the H level, the operation of the gap data generation circuit 7 is started, and the gap data is sequentially generated and transmitted. At the same time, the selection signal X is sent to the selection circuit 3, and the output of the gap data generation circuit 7 is controlled to be the output of the selection circuit 3. When the transmission of the specified amount of gap data is completed, the gap data generation signal (F) is set to L level, and the transmission of gap data is stopped.

Simultaneously with the end of the transmission of the gap data, the audio data recording signal (D) is set to the H level, and the audio processing circuit 9 starts outputting the audio data. On the other hand, the selection signal Y is sent to the selection circuit 5 and the selection signal X is sent to the selection circuit 3, and the output data of the audio processing circuit 9 is controlled to be output from the selection circuit 3 through the modulation circuit 6. When the specified amount of audio data has been transmitted, the audio data recording signal (D) is set to the L level, and the transmission of the audio data is stopped. At the same time, the gap data generation signal (F) is set to the H level, the operation of the gap data generation circuit 7 is started, and the gap data is sequentially generated and transmitted.
At the same time, the selection signal X is sent to the selection circuit 3, and the output of the gap data generation circuit 7 is controlled to be the output of the selection circuit 3. When the transmission of the specified amount of gap data is completed, the gap data generation signal (F) is set to L level, and the transmission of gap data is stopped.

At the same time that the transmission of the gap data is completed, the video data recording signal (E) is set to the H level, and the video processing circuit
Causes 10 to start outputting video data. On the other hand, the selection signal Y is sent to the selection circuit 5 and the selection signal X is sent to the selection circuit 3, and the output data of the video processing circuit 10 is controlled to be output from the selection circuit 3 through the modulation circuit 6. When the specified amount of video data has been sent, the video data recording signal (E) is
Level and stop sending video data. at the same time,
The gap data generation signal (F) is set to the H level, the operation of the gap data generation circuit 7 is started, and gap data is sequentially generated and transmitted. At the same time, the selection signal X is supplied to the selection circuit 3
And the output of the gap data generation circuit 7 is
Is controlled so that the output becomes. The output of the last gap data is continued until the next edge of the recording control signal arrives. Thereafter, a series of operations starting from generation of preamble data is repeated, and desired data is regularly recorded on the tape by the circuit of FIG.

Next, the main circuit blocks of FIG. 1 will be described. First, the start information generation circuit will be described. The start information generation circuit 4 is a circuit that generates information for accurately specifying the start position of valid data on one track. The start position information is a valid track recorded on the same track.
Information for specifying the recording position of data or search information
It is. An example of the output form of the start information generation circuit 4 is shown in FIG. In other words, the output of the start information is in the form of a block.
Following the first synchronization pattern, the first auxiliary data
Dummy signal, two types of block numbers, and a second complement
One block is constituted by the second dummy signal as auxiliary data . For example, 43 such blocks constitute one start information recording area in succession. The first in each block
The dummy signal is selected so as to cancel the DC component of the synchronization pattern, and does not diverge the number difference between “1” and “0” in the modulated recording sequence. If the number difference between “1” and “0” in the modulated recording sequence does not diverge, the DC component included in the recording sequence becomes zero. Generally, in a VTR, signals are transmitted and received between a head and a circuit via a rotary transformer. Therefore, the DC component is cut, and if the DC reproduction is not performed correctly, the reproduced data may not be accurately reproduced. For this reason, in the present invention, the operation of setting the DC component of the recording sequence to zero is performed.

The first block number is, for example, 0 to 42.
Is represented by a 6-bit binary value starting from 00. Second
Are the first block numbers "1", "0", "
A bit pattern in which all “0” and “1” are inverted.
By doing so, "1" in the first and second block numbers
And the number difference between “0” and “0” becomes 0, and “1” in the entire recording sequence
There is no divergence of the difference between the numbers "0" and "0". If the number difference between “1” and “0” in the recording sequence does not diverge, the DC component of the recording sequence becomes zero, so that “1” and “0” at the output stage of the modulation circuit 6 are changed. The number difference affects the presence or absence of a DC component. Therefore, at the output of the start information generation circuit 4, it is sufficient to generate and output data such that the sequence after modulation has a desired value. Since the processing in the modulation circuit 6 is uniquely determined, it is easy to determine a modulation input that produces a desired result after modulation. The second dummy signal is used, for example, to control the DC component in one block as a whole. That is,
A pattern necessary for keeping the difference between the numbers "1" and "0" in one block within a predetermined value is selected and used as a second dummy signal.

At the time of reproduction, the above-mentioned synchronization pattern of 00110000000000111 is detected, and the recording area of the start information is specified by extracting the block number. In addition, the detection error of the block number caused by an error at the time of reproduction is caused by the fact that the same block number is recorded in two types, and if the relationship uniquely determined is different, there is an error in the block number. Can be detected. Also, utilizing the fact that the block lengths are equal and the block numbers are continuous, from one detected synchronization pattern or block number,
It is possible to correct an error in a synchronization pattern or an error in a block number relating to a succeeding or preceding block. Therefore, the present invention can correct not only a DC component but also a reproduction error in a block.

As described above, the start position of the audio or video data on the track following the start position information can be relatively accurately specified based on the start position information accurately specified at the time of reproduction. As a result, when rewriting data that has already been recorded, such as editing, it is only necessary that the mechanism has a mechanism accuracy such that the rewriting start position falls within the gap immediately before the data to be rewritten. This is a very easy condition from the point of view of the mechanism accuracy, and the
(Several 100 μs) does not need to be maintained, and there is no practical problem even with a gap length of about 60 μs. Therefore, not only can the effective recording area on the track be greatly enlarged, but also the editing accuracy can be improved more than before. In other words, whereas the conventional control determines the editing start position based on incorrect track start information, the present invention edits the actual recording start position based on the information actually written on the tape. The start position is specified with high accuracy. This is the first object of the present invention, and it is possible to prevent a large increase in mechanism accuracy and circuit scale which is unnecessary for performing high-accuracy editing. That is, by using the present invention, high-accuracy editing can be performed with the same mechanical accuracy as that of a conventional home VTR, that is, while satisfying the conditions of small size, light weight, and low cost.

Next, the search information generation circuit 8 will be described. As described above, in this circuit, for example, a time code or the like is received, changed to a form to be recorded, and generated. FIG. 4 shows a block configuration of an output form of the search information generation circuit 8. For example, 15 blocks shown in FIG. 4 continuously form a search information recording area in one track.
This one block consists of, for example, the above-mentioned synchronization pattern of 0001100000000010, five-word data, parity data for error detection or correction of the five-word data, and a block number. At the time of reproduction, the synchronization pattern of 0001100000000010 is detected, and the recording area of the start information is specified by extracting the block number. In addition, the detection error of the block number caused by the error at the time of reproduction is performed by using one of the correctly detected synchronization pattern or block number by using the fact that the block lengths are equal and the block numbers are continuous. Or, it is possible to correct an error in the synchronization pattern or an error in the block number for the preceding block. Subsequently, the presence / absence of an error in five words in the block is detected by the corresponding parity data. If the error is corrected, the error is corrected, and if the error is not corrected, an error flag is attached and transmitted. Subsequent processing is the same as ordinary error processing, and a description thereof will be omitted. The search information is used for searching for a signal to be reproduced.

Next, the audio and video processing circuits 9 and 10 will be described. For these circuits,
The only difference is whether the content of the data to be recorded is video data or audio data, but the basic processing content and data output form are the same. FIG. 5 shows an output form. In FIG. 5, one block is the synchronization pattern of 01100000000001101 described above, two words of block information, one word of error detection parity data for the block information, 128 words of real data, and eight words of parity data for this data. Consisting of The block information is, for example, a block number or identification information of audio and video. As for the block number, the audio and video blocks are sequentially numbered. For example, 9 blocks of audio and 88 of video
In the case of a block, a block number from 0 to 96 is added to the audio block and the video block. For audio and video identification information, for example, "1" is assigned to audio data, and "0" is assigned to video data. At this time, the audio block numbers are 0 to 8, and the video block numbers are 9 to 96. Therefore, the audio / video identification information and the block number 2
Audio and video can be distinguished by the type of information. This greatly reduces the probability that audio and video will be incorrectly processed due to playback errors.

During reproduction of audio and video data, a synchronization pattern of 01100000000001101 is detected, and the block number and audio / video data are detected.
The subsequent processing path is separated by extracting the video identification information. Note that an error in the block number caused by an error during reproduction can be detected by an error detection parity of the block information. In addition, by utilizing the fact that the block lengths are equal and the block numbers are continuous, from one correctly detected synchronization pattern or block number, an error in the synchronization pattern relating to the succeeding or preceding block, Number errors can be corrected.

As described above, according to the present invention, the synchronization pattern added to various data is changed with a simple circuit configuration, and at the time of reproduction, these synchronization patterns are distinguished from each other and detected to determine the type of the reproduction data. I do. Therefore, for example, the start information is reproduced as video data, and an erroneous image is effectively prevented from being displayed on the screen. Note that the above-mentioned synchronous pattern of 00110000000000111 1 0001100000000010 01100000000001101 indicates a pattern at the detection point. That is, the synchronization pattern on the tape differs depending on the modulation method, and does not always match the synchronization pattern described above. However, the demodulation result, which is the reverse process of the modulation, always matches the above-mentioned synchronization pattern. Therefore, only the pattern of the detection point is sufficient as the synchronization pattern to be defined.

As described above, the present invention enables control comparable to a broadcast VTR with the mechanical accuracy of a conventional home VTR. In the above description, the advantage of making the DC component zero is shown, but a pilot signal can be generated by applying the process of making the DC component zero. The following briefly describes this method.

The pilot signal is obtained by superimposing signals of different frequencies on adjacent tracks, and comparing the crosstalk amount of the pilot frequency from the adjacent track in a certain track (T). Then, based on the difference in the amount of crosstalk, the reproducing head detects the amount of deviation from the track (T) to be traced, and returns the head to the original track. For example, assume that the preamble has a function of generating a pilot frequency. For example, as shown in FIG. 6, a preamble generating a pilot of frequency f ₀ is generated in track 1, a preamble not generating a pilot in track 2, and a pilot having a frequency f ₁ different from f ₀ is generated in track 3. Each preamble to be recorded is recorded.

At this time, as shown in FIGS. 6 (a) and 6 (b), when the head which must correctly trace the track 1 traces toward the track 0, the amount of crosstalk appearing in the output of the head is equal to the track. The pilot frequency f ₀ component from 0 is higher than the pilot frequency f ₁ component from track 2. On the other hand, FIG.
As shown in (c) and (d)), when the head traces the track 1 correctly, the amount of crosstalk appearing in the head output is related to the pilot frequency f ₀ component from the track 0 and the pilot frequency from the track 1. Frequency f ₁
The components are equal. Therefore, the frequency f ₀ component and the frequency f ₁ component of the crosstalk in the head output of the track 1 may be compared, and control may be performed so as to change the relative position of the head with respect to the track 1 so that both components become equal.

"1" and "0" to be recorded on the tape in unit time
Is defined as N and the difference between the numbers is defined as DSV. If DSV is always finite and N becomes infinite, DSV / N
→ It becomes 0. This indicates that the DC component is zero from the definition of the Fourier transform. Further, even if the DSV is always finite, the increase and decrease of the DSV may change periodically. Such a D
The energy of the series of "1" and "0" on the tape where the SV changes periodically concentrates on the frequency which is the reciprocal of the cycle. In other words, the spectrum of this frequency becomes very large as compared with the neighboring frequencies. Therefore, if the increase / decrease cycle of the DSV is controlled to be the reciprocal of the pilot frequency, the recording sequence itself generates a pilot signal. When a pilot signal is simply superimposed on a recording signal as in the related art, the pilot signal is equivalent to noise for the recording signal. Therefore, the effect of improving the error rate of the reproduced signal by reducing the tracking error due to the pilot signal is reduced by the superimposed pilot signal. On the other hand, when the recording signal itself generates the pilot signal, the reproduction error rate does not deteriorate due to the superposition of the pilot signal. From such a viewpoint, it is desirable that the recording sequence itself generates the pilot signal. Since the present invention originally has the ability to perform control to reduce the DC component to zero, by performing the cycle of removing the DC component and the control of DSV at the cycle of the reciprocal of the pilot frequency, the pilot signal can be recorded in the recording sequence itself. Can be generated by

[0029]

According to the present invention, information that can specify a data recording start position is recorded on each track on a tape.
The recording start position of the actual data on the track can be easily specified. Accordingly, editing accuracy equivalent to that of broadcasting can be obtained with the same mechanism accuracy as that of a conventional home VTR, and it can be realized with a small size, light weight, and low price. As described above, the present invention can greatly contribute to performance and cost in realizing a home digital VTR.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of FIG. 1;

FIG. 3 is an explanatory diagram of a recording block of start position information.

FIG. 4 is an explanatory diagram of a recording block of search information.

FIG. 5 is an explanatory diagram of recording blocks of audio and video data.

FIG. 6 is an explanatory diagram of tracking control in the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control signal generation circuit 2 preamble generation circuit 3 selection circuit 4 start information generation circuit 5 selection circuit 6 modulation circuit 7 gap data generation circuit 8 search information generation circuit 9 audio processing circuit 10 video data processing circuit

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-220482 (JP, A) JP-A-57-3280 (JP, A) JP-A-63-113980 (JP, A)

Claims (10)

(57) [Claims] 1. A digital signal recording apparatus having recording means for recording a digital signal on a track on a tape-shaped recording medium, wherein an absolute position in the track of valid data or search information on the track is specified. Position information generating means for forming start position information on the track for starting, the start position information generating means connecting a plurality of first synchronization blocks each including a first synchronization pattern and a synchronization block number. A digital signal recording apparatus for generating a starting position information sequence comprising: 2. The digital signal recording apparatus according to claim 1, wherein the synchronous block number comprises a first block number and a second block number obtained by inverting the first block number. 3. A digital signal recording apparatus having recording means for recording a digital signal on a track on a tape-shaped recording medium, wherein an absolute position of valid data or search information on the track in the track is specified. Position information generating means for forming start position information on the track for the first time, the first position information generating means comprising: first auxiliary data for generating a first synchronization pattern, a synchronization block number, and a pilot signal; A digital signal recording apparatus for generating a start position information sequence formed by connecting a plurality of first synchronization blocks each including second auxiliary data. 4. A digital signal recording apparatus having recording means for recording a digital signal on a track on a tape-shaped recording medium, wherein an absolute position of valid data or search information on the track in the track is specified. Position information generating means for forming start position information on the track for recording, preamble generating means for the recording means to form a pattern suitable for clock reproduction at least at the beginning of the track, and tape of valid data A search information generating means for forming search information for searching for an upper position on the track; and a data generating means for forming the valid data on the track in at least one area. The position information generating means links a plurality of first synchronization blocks each including a first synchronization pattern and a synchronization block number. The search information generation means generates a start position information sequence including a second synchronization pattern different from the first synchronization pattern, a plurality of data, parity for error detection or correction, and a synchronization block number. And generating a search information sequence formed by connecting a plurality of second synchronization blocks.
A digital signal recording apparatus for generating a data sequence formed by connecting a plurality of third synchronization blocks including a third synchronization pattern different from the first synchronization pattern. 5. A digital signal recording method for recording a digital signal on a track on a tape-shaped recording medium, wherein a start position for specifying an absolute position in the track of valid data or search information on the track. A digital signal recording method, wherein information is formed on the track, and the start position information is formed by connecting a plurality of first synchronization blocks each including a first synchronization pattern and a synchronization block number. 6. The digital signal recording method according to claim 5, wherein the synchronous block number comprises a first block number and a second block number obtained by inverting the first block number. 7. A digital signal recording method for recording a digital signal on a track on a tape-shaped recording medium, wherein a start position for specifying an absolute position in the track of valid data or search information on the track. Information is formed on the track, and the start position information includes a plurality of first synchronization blocks each including a first synchronization pattern, a synchronization block number, and first and second auxiliary data for generating a pilot signal. A digital signal recording method characterized by being connected. 8. A table for recording a digital signal on a track.
And a start-point information for specifying an absolute position in the track of valid data or search information on the track, the start position information being a first synchronization information. A recording medium, wherein a plurality of first synchronization blocks each including a pattern and a synchronization block number are connected. 9. The recording medium according to claim 8, wherein the synchronous block number comprises a first block number and a second block number obtained by inverting the first block number. 10. A tape for recording digital signals on tracks
A recording medium having a loop shape , wherein start position information for specifying an absolute position in the track of valid data or search information on the track is formed on the track; A recording medium comprising a plurality of first synchronization blocks each including a synchronization pattern, a synchronization block number, and first and second auxiliary data for generating a pilot signal.