JPH04315807A - Vtr - Google Patents

Abstract

PURPOSE:To immediately judge the state of a magnetic tape to be used at the time of recording and reproducing in a VTR. CONSTITUTION:In the VTR in which a video signal is recorded on a magnetic tape, a subcode is added to the video signal and recorded, the damaged state of the magnetic tape is detected by detecting means 48 and 52 and the data of the detected damaged state are recorded as subcode at the time of recording.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a digital VT system that converts a video signal into digital data, records it on a magnetic tape, and plays it back.
The present invention relates to a VTR suitable for application to R.

0002

[Prior Art] A helical scan type rotary head device transmits video signals and the like onto a magnetic tape once every unit time.
2. Description of the Related Art Digital VTRs have been put into practical use, which record and reproduce diagonal tracks by digitizing video signals. This is because digitalization allows recording and reproduction of high-quality images.

[0003] By the way, the magnetic tapes (video tapes) used in such VTRs are not always perfect, and sometimes those in poor condition are used. If a magnetic tape in poor condition is used for recording or playback, many dropouts occur during playback of recorded video signals, resulting in unsightly playback of video. Furthermore, in the worst case, some damage may be caused to the tape running mechanism on the VTR side.

0004

[Problem to be Solved by the Invention] Conventionally, however, such dropouts occur when the actually recorded video signal is played back and the video displayed on the screen of a monitor receiver or the like is viewed. This was something that could only be known for the first time, and it was not possible for the person performing the recording operation to judge the tape condition during recording.

In view of the above, the present invention provides a VTR that can immediately determine the condition of a magnetic tape used during recording and playback.
The purpose is to provide

[0006]

[Means for Solving the Problems] The present invention is a VTR that records a video signal on a magnetic tape 1 and also adds a subcode to the video signal to detect a damaged state of the magnetic tape 1 during recording. The damage state is detected by means 48 and 52, and data regarding the detected damage state is recorded as a subcode.

[0007] Furthermore, when the detected damage state of the magnetic tape is below a predetermined level, recording is stopped.

Furthermore, when the detected damage state of the magnetic tape is below a predetermined level, the recording mode is changed to one with a lower recording density.

[0009] Furthermore, when the detected damage state of the magnetic tape is below a predetermined level, the recording position is skipped by a predetermined section.

[0010] The present invention also provides a VTR that records and reproduces video signals on a magnetic tape and also adds a subcode to the video signal. This is what I did.

[0011]

[Operation] By doing this, when using a magnetic tape on which data regarding the damage state is recorded in the subcode, it is possible to determine the state of the tape based on the data regarding the damage state included in the subcode that is played back. It can be immediately determined whether there is any tape damage, and the negative effects of tape damage can be minimized.

[0012] Furthermore, by stopping recording, changing to a mode with lower recording density, and skipping a predetermined section of the recording position depending on the detected damage state, appropriate processing can be carried out according to the damage state. be exposed.

Furthermore, by recording the number of times the magnetic tape has been recorded or played back in the subcode, the condition of the magnetic tape can be determined from the number of times the magnetic tape has been used.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

This example is applied to a digital VTR that records digital video signals, and is configured as shown in FIG. First, to explain the recording system circuit, the input terminal 11
The analog video signal supplied to the analog/digital converter 12 is supplied to the analog/digital converter 12 and converted into a digital video signal. Then, the digital video signal output from the analog/digital converter 12 is supplied to the digital video processing circuit 13,
A predetermined digital signal processing is performed to obtain a digital video signal having a data structure for recording. Then, the digital video signal output from the digital video processing circuit 13 is supplied to the parity generation circuit 14, and a correction code is added thereto. The digital video signal output from the parity generation circuit 14 is then transferred to a mixer 15.
and mixes audio data and subcode, which will be described later.

Further, reference numeral 16 in the figure indicates an analog audio signal input terminal, and the audio signal obtained at this input terminal 16 is supplied to an analog/digital converter 17 and converted into a digital audio signal. And analog/digital converter 17
supplies the digital audio signal outputted by the digital audio processing circuit 18 to perform predetermined digital signal processing,
A digital audio signal with a data structure for recording. The digital audio signal output from the digital audio processing circuit 18 is then supplied to the parity generation circuit 19. Also, 2
0 indicates a subcode generation circuit, and the subcode generated by this subcode generation circuit 20 is sent to the parity generation circuit 19.
supply to.

In this case, in this example, the subcode generated by the subcode generation circuit 20 includes data regarding the damage state of the magnetic tape and data regarding the number of times of recording and reproduction. Data regarding the damage state and data regarding the number of times of recording/playback may be supplied from the system controller 25 of the VTR or from a subcode detection circuit 46, which will be described later. The data supplied from the system controller 25 is data regarding the damage state of the magnetic tape, and the damage state of the magnetic tape is determined by the system controller 25 based on the output data of the dropout counter 48 and the damage detection circuit 52, which will be described later. is recorded. This damage state is, for example, data indicating which rank it is among four ranks. Further, the data supplied from the subcode detection circuit 46 is data regarding the number of times of recording and reproduction of this magnetic tape (the sum of the number of recordings and the number of reproductions). The data obtained by adding one time to the detected number of recording/playback times is added to the subcode as new data.

The parity generation circuit 19 adds a correction code to the supplied digital audio signal and subcode. Then, the digital audio signal and subcode outputted by the parity generation circuit 19 are supplied to the mixer 15, and the digital video signal, digital audio signal, and subcode are
Digital data of the same series.

Then, the digital data output from the mixer 15 is supplied to a modulation circuit 21 to be modulated for recording. Then, the modulated digital data is supplied to the mixer 22, and the ATF (automatic track following control) obtained at the terminal 23
Combine pilot signals, etc. And mixer 2
The digital data output by the magnetic tape 2 is supplied to an equalizer 24 to perform equalization suitable for the recording characteristics of the magnetic tape. and,
The output signal of the equalizer 24 is supplied to recording magnetic heads 3 and 4 attached to a rotating head drum via recording amplifiers 26 and 27 and a rotary transformer (not shown).
Record on magnetic tape 2. In this case, the magnetic heads 3, 4
correspond to a leading head HL and a trailing head HT attached to a rotating head drum, which will be described later.

Note that this recording system circuit records two tracks almost simultaneously using a double azimuth head, which will be described later, so each circuit is actually designed to be able to process two systems of recording data at the same time.

Next, to explain the configuration of the reproducing side, the signal reproduced from the magnetic tape 2 by the reproducing magnetic heads 5 and 6, which are different from the recording magnetic heads 3 and 4 mentioned above, is transferred to the rotary transformer (Fig. (not shown) and reproduction amplifiers 31 and 32 to an equalizer 33, and the equalizer 33 returns the signal to the original signal. Then, the output signal of the equalizer 33 is supplied to a demodulation circuit 35 and a PLL circuit (phase locked loop circuit) 36, and the demodulation circuit 35 outputs the signal to the PLL circuit 3.
6 performs demodulation in synchronization with the clock detected from the reproduced signal. Furthermore, the reproduced data demodulated by the demodulation circuit 35 is supplied to the time base collector 37, and the time base collector 37 performs time axis correction in synchronization with the clock detected by the PLL circuit 36 to remove time axis fluctuation components. do. Then, the playback data outputted by the time base collector 37 is supplied to error correction circuits 38 and 39, the error correction circuit 38 performs error correction on the video data (digital video signal) in the playback data, and the error correction circuit 39 performs playback. Corrects errors in audio data and subcodes in the data.

Then, the digital video signal output from the error correction circuit 38 is supplied to the digital video processing circuit 40 to perform predetermined digital signal processing, and convert the digital video signal in the data configuration for recording into the original digital video signal. Convert. Then, the digital video signal outputted by the digital video processing circuit 40 is supplied to the digital/analog converter 41 to be converted into an analog video signal, and the converted analog video signal is supplied to the output terminal 42.

The audio data output by the error correction circuit 39 is then supplied to the digital audio processing circuit 43 to perform predetermined digital signal processing and convert the digital audio signal having the data structure for recording into the original digital audio signal. do. Then, the digital audio signal outputted by the digital audio processing circuit 43 is supplied to the digital/analog converter 44 to be converted into an analog audio signal, and the converted analog audio signal is supplied to the output terminal 45.

The subcode output from the error correction circuit 39 is supplied to a subcode detection circuit 46, and the subcode detected by the subcode detection circuit 46 determines the content of the reproduced subcode. Among the determined data, if there is data regarding the damage state of the magnetic tape and data regarding the number of times of recording/playback, the respective data are supplied to the subcode generation circuit 20 and the system controller 25.

Further, in the figure, numeral 34 indicates an envelope detection circuit, and this envelope detection circuit 34 is connected to the reproduction amplifier 3.
1 and 32 output signals are supplied, and the detected output is supplied to a dropout counter 48. This dropout counter 48 counts the number of occurrences of dropouts in which the envelope detection level temporarily decreases, and supplies the data counted by the dropout counter 48 to the system controller 25.

Further, the output signals of the reproducing amplifiers 31 and 32 are supplied to an ATF circuit 46, which generates a tracking error signal from the level of the beat component of the regenerated pilot signal, and uses this tracking error signal as a signal for adjusting the phase of a capstan servo, for example. Supplies the servo circuit.

Note that this reproduction circuit reproduces two tracks almost simultaneously using a double azimuth head, which will be described later, so in reality, like the recording circuit, each circuit can process two systems of reproduction data at the same time. It's like this.

In the figure, reference numeral 51 denotes a photosensor, which is placed on the running part of the magnetic tape 2 and detects the state of the edge portion of the magnetic tape 2 based on the reflected state of the light irradiated onto the magnetic tape 2. Monitor. Then, the output of the photosensor 51 is supplied to a damage detection circuit 52, and the damage detection circuit 52 determines from the output of the photosensor 51 whether or not the magnetic tape 2 is normal. That is, if the edge of the magnetic tape 2 is partially stretched or the tape condition is deteriorated, this is detected. Then, the detection data of the damage detection circuit 52 is supplied to the system controller 25. This detection by the damage detection circuit 52 is performed both during recording and during reproduction.

Further, a display unit 28 made of a liquid crystal display or the like and arranged on the front panel of the VTR is connected to the system controller 25, and displays data regarding the damage state of the magnetic tape determined by the subcode detection circuit 46. Based on the data regarding the number of recordings and reproductions, the display unit 28 displays the damage state of the mounted magnetic tape 2 and the number of recordings and reproductions using characters, figures, etc. Furthermore, when data regarding the damage state of the magnetic tape is not recorded in the subcode, the data counted by the dropout counter 48 and the damage detection circuit 52
The system controller 25 judges the detection data of
The display unit 28 displays the current damage state of the attached magnetic tape 2.

Now, the arrangement of the magnetic heads 3, 4, 5, and 6 used in the VTR of this example on the rotary head drum will be explained with reference to FIG. 2. In FIG. 2, 1 is the rotary head drum. A magnetic tape 2 is wound around the circumferential surface of the rotary head drum 1 at 180 degrees, and magnetic heads HL and HT having different azimuth angles are mounted in close proximity to form a pair of double azimuth heads (first double azimuth head) is constructed. At this time, the preceding head HL
The spacing between the leading head HL and the trailing head HT is set to GL, and the leading head HL and the trailing head HT are fixed with an offset in the height direction (direction of the drum's rotation axis) by one track pitch. Furthermore, this first double azimuth head and 18
Another set of double azimuth heads (
A second double azimuth head) is constructed. This second
Like the first double azimuth head, the preceding head HL has a different azimuth angle.
' and a trailing head HT', and the positional relationship between them is the same as that of the first double azimuth head (that is, the interval GL, the step difference is one track pitch). It is assumed that the azimuth angles of both the leading heads HL and HL' are the same, and the azimuth angles of both the trailing heads HT and HT' are also the same. In this example, the leading head HL and trailing head HT constituting the first double azimuth head are the recording magnetic heads 3 and 4 shown in FIG. 1, and the leading head constituting the second double azimuth head Let HL' and trailing head HT' be the reproducing magnetic heads 5 and 6 shown in FIG.

Next, the track pattern on the magnetic tape of data recorded and reproduced by the VTR having the configuration shown in FIG. 1 will be explained with reference to FIG.

FIG. 3A shows the arrangement of data recorded on one track (or one segment). In the figure, the left end of the track is the head entry side, and the right end is the head separation side. Furthermore, the shaded area is a margin or IBG (interblock gap) where no data is recorded. For example, a pulse signal having a frequency equal to the bit frequency of data is recorded in the preamble or postamble to facilitate locking of a PLL provided on the reproduction side for bit clock extraction.

[0033] ATF at the end of one track on the head entry side.
The pilot signal for The encoded video data and audio data are recorded in the next section. Furthermore, a recording section for only audio data is provided after this video and audio section. Then, subdata (subcode) is recorded in the recording section closest to the head separation side.

The video and audio sections consist of a number of sync blocks, and a more detailed data arrangement of the sync blocks is shown in FIG. 3B. At the beginning, a block synchronization signal indicating the start of a block is located, followed by a sync block SB for identifying the block, and then an ADR.
A threshold value THR for determining the number of bits allocated to C is located. The subsequent block address BA is for the address on the screen. Furthermore, NEXT is
Indicates the length of the block. The encoded data generated by ADRC includes dynamic range DR', minimum value MIN
', a group BPL of code signals corresponding to each pixel. Furthermore, audio data is inserted into a section separate from image data within this section. The parity of the error correction code is placed at the end of the sync block. The arrangement of the sync blocks shown in FIG. 3B is an example, and in consideration of the amount of video data, the amount of audio data, and the amount of parity data, sync blocks with a data arrangement not shown are also used.

The recording section for only audio data and the recording section for sub-data also have the same data arrangement as described above. FIG. 3C shows the data arrangement of the sync block in the sub-data section.

At the beginning, a block synchronization signal indicating the start of a block is located, followed by an ID signal, and then subdata (subcode). In this example, data regarding the damage state of the magnetic tape and data regarding the number of times of recording/playback are recorded in a part of the sub-data recording area. The parity of the error correction code is placed at the end of the sync block. The ID signal includes a code for identifying the sub-data area, a start ID, a frame ID, a track address, a skip ID, a program number, a block number, etc. This ID signal is required not only during normal playback but also when restoring an image using playback data during high-speed playback.

Next, the recording and reproducing operations of the VTR constructed in this manner will be explained, focusing on the detection of the state of the magnetic tape. First, during recording, the recording system circuit from the input terminals 11 and 16 to the magnetic heads 3 and 4 records video signals and the like on the magnetic tape 2, and at the same time, the recorded signals are transferred to the magnetic head for reproduction.
. Further, detection data of the damage detection circuit 52 (data indicating whether the tape edge is normal or not) is also supplied to the system controller 25. Then, the system controller 25 judges each of the supplied data and ranks the damage state of the magnetic tape being recorded into four levels (ranks 1, 2, 3, and 4). Of these four ranks, rank 1 is the normal state, and as the number of dropouts and the number of distorted tape edges increases, rank 1 → rank 2 → rank 3 → rank 4
The operation at each rank is determined in advance as shown in Table 1 below.

[0038]

[Table 1]

As shown in Table 1, in the state of rank 1, normal recording continues, and in the state of rank 2, the magnetic tape 2 is fast-forwarded by, for example, the number of seconds that data can be recorded, and this section is skipped. Continue recording. This is done because the damage state of the magnetic tape is reduced.
This is because it is often temporary. In the state of rank 3, the recording mode is changed to a mode with a lower recording density and recording is continued. This low recording density mode may be a mode in which the pitch of the tracks formed on the magnetic tape is the widest, or a mode in which the transmission rate of the recorded digital video signal is the lowest even though the track pitch is the same. Note that when recording is already being performed in the mode with the lowest recording density, the recording mode is not changed at rank 3. When the rank is 2 or 3, a warning is given that the damage state of the magnetic tape is in a bad rank. This warning is given in text or the like on the display section 28 connected to the system controller 25. It is determined that the rank 4 condition has deteriorated to the extent that recording is no longer possible, so recording is stopped and the tape cassette containing the magnetic tape is transferred to the VTR.
Make an eject operation to eject the product from the main body.

In parallel with these operations, the system controller 25 supplies the determined rank data to the subcode generation circuit 20, and records the determined rank as data regarding the damage state of the magnetic tape included in the subcode. .

Furthermore, when recording a new signal on a magnetic tape on which a video signal or the like has already been recorded, the subcode detection circuit 46 of the reproduction system detects the number of recording/playbacks from the reproduced subcode. The detected number of recording/playbacks is displayed on the display unit 28 under the control of the system controller 25.
At the same time, the subcode generation circuit 20 generates a subcode that includes the data of the number of times added by one to the number of times of recording/playback.
This subcode is recorded on the magnetic tape 2.

Furthermore, during reproduction, the subcode detection circuit 4
Detects the number of recording/playbacks from the subcode played by 6,
The system controller 2
5, the subcode is displayed on the display unit 28, and the subcode generation circuit 20 generates a subcode containing data of the number of times added by one to the detected number of recording/playbacks, and only this subcode is recorded on the magnetic tape 2. let That is, when only this subcode is recorded, only the subdata area (block) shown in FIG. 3C is rewritten and updated, and the video data and audio data are not rewritten.

By performing the control during recording and playback in this manner, the recording control shown in Table 1 is performed according to the state of occurrence of tape damage during recording, and the state of occurrence of tape damage is It is recorded as a code, preventing recording even when the magnetic tape is in a bad state of damage, and allowing good recording and playback. Further, when this magnetic tape is subsequently used, the damage state can be determined from the recorded data of the subcode, which is convenient for use. Furthermore, since the occurrence status of this tape damage is displayed on the display section 28, the VTR operator is also notified of this, and the operator can decide whether to replace the tape, etc. can. Furthermore, the number of times the magnetic tape is used (the number of times it is recorded/played) is also displayed based on the subcode data, so it is convenient to judge the condition of the magnetic tape from this point as well.

[0044] When performing the above-mentioned ranking,
The determination may also include data regarding the number of times of recording and reproduction in the reproduced subcode. That is, in the case of a magnetic tape that has been recorded and reproduced many times, it may be determined that it has a worse rank than a magnetic tape that has been recorded and reproduced less frequently. Further, it is not necessary to perform all the operations in each rank described above, and the operations in some ranks shown in Table 1 may be omitted. For example, recording may be stopped at the next rank shown in rank 1 where normal recording/reproduction is performed, and ranks 2 and 3 shown in Table 1 may be omitted. In this case, only the state of occurrence of tape damage may be displayed on the display section 28 in a finer number of stages. Furthermore, detection of tape damage may be performed using other methods. For example, the number of errors occurring in the reproduced digital data may be counted, and if the number of errors occurring is large, it may be determined that there is a lot of damage to the tape.

[0045]

According to the present invention, it is possible to immediately determine what condition the tape is in based on the damage condition data included in the reproduced subcode, and the adverse effects of tape damage can be minimized.

[0046] Also, by stopping recording, changing to a mode with lower recording density, and skipping a predetermined section of the recording position depending on the detected damage state, appropriate processing can be carried out according to the damage state. be exposed.

Furthermore, by recording the number of times the magnetic tape has been recorded or played back in the subcode, the condition of the magnetic tape can be determined from the number of times the magnetic tape has been used.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a rotary head drum according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a data structure according to one embodiment.

[Explanation of symbols]

2 Magnetic tape 3,4 Magnetic head for recording 5, 6 Magnetic head for reproduction 11 Analog video signal input terminal 16 Analog audio signal input terminal 20 Subcode generation circuit 25 System controller 28 Display section 34 Envelope detection circuit 42 Analog video signal output terminal 45 Analog audio signal output terminal 46 Subcode detection circuit 48 Dropout counter 51 Photo sensor 52 Damage detection circuit

Claims (5)

[Claims] Claim 1: A VT that records a video signal on a magnetic tape and adds a subcode to the video signal.
A VTR characterized in that, during recording, a damaged state of the magnetic tape is detected, and data regarding the detected damaged state is recorded as the sub-code. 2. The VTR according to claim 1, wherein recording is stopped when the detected damage state of the magnetic tape is below a predetermined level. 3. A first method characterized in that when the detected damage state of the magnetic tape is below a predetermined level, the recording mode is changed to one with a lower recording density.
VTR described in section. 4. The magnetic tape according to claim 1, wherein when the detected damage state of the magnetic tape is below a predetermined level, the recording position is skipped by a predetermined section.
T.R. 5. A VTR that records and plays back a video signal on a magnetic tape and adds a subcode to the video signal, wherein the subcode records the number of times the magnetic tape is recorded or played back. A VTR characterized by: