JP2961930B2 - VTR - 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 VT for converting a video signal into digital data and recording and reproducing it on a magnetic tape.
It relates to a VTR suitable for application to R.

[0002]

2. Description of the Related Art A helical scan type rotary head device transfers a video signal or the like on a magnetic tape at a time of one unit time.
A digital VTR that digitizes and records and reproduces a video signal has been put to practical use when forming and recording diagonal tracks for each book, and reproducing this. This is because recording and reproduction of high-quality images can be performed by digitization.

[0003] Magnetic tapes (video tapes) used in such VTRs have the same format.
Even if it is used for TR, there are individual differences in characteristics. Ideally, according to the characteristics of each magnetic tape,
It is preferable to adjust the recording system circuit and the reproduction system circuit.

[0004]

However, in practice, many magnetic tapes perform recording / reproducing with the same characteristics, ignoring the difference between the individual characteristics of the magnetic tape. Even if the recording system circuit and the reproduction system circuit are changed, a
A variety of characteristics were prepared, and a tape cassette loaded with a magnetic tape was provided with a projection or the like indicating any of the tape characteristics, so that the characteristics of the circuit could be switched to several levels. Due to the difference in the characteristics, it has not been possible to finely change the characteristics of the circuit. Therefore, it could not be said that the characteristics of the magnetic tape were best utilized.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a VTR capable of easily setting optimum circuit characteristics according to the characteristics of a magnetic tape to be used.

[0006]

According to the present invention, as shown in FIG. 1, for example, a VT for recording a video signal on a magnetic tape 1 and adding a subcode to the video signal for recording.
In R, at the time of recording, the frequency characteristic of the magnetic tape 1 is measured by the measuring circuit 34, and data on the measured frequency characteristic is recorded as a subcode.

[0007]

With this arrangement, the optimum adjustment state of the recording circuit and the reproduction circuit can be determined from the data on the frequency characteristics of the magnetic tape included in the subcode. Even so, the circuit can always be adjusted to an optimum state.

[0008]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

This embodiment is applied to a digital VTR for recording a digital video signal, and is configured as shown in FIG. First, the recording system circuit will be described.
1 is supplied to an analog / digital converter 12 to be 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 configuration 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. Then, the digital video signal output from the parity generation circuit 14 is
, And mixes audio data and sub-code described later.

In the figure, reference numeral 16 denotes an analog audio signal input terminal. The audio signal obtained at the input terminal 16 is supplied to an analog / digital converter 17 and converted into a digital audio signal. And the analog / digital converter 17
Is supplied to the digital audio processing circuit 18 to perform predetermined digital signal processing,
It is a digital audio signal having a data configuration for recording. Then, the digital audio signal output from the digital audio processing circuit 18 is supplied to the parity generation circuit 19. Also,
Reference numeral 20 denotes a subcode generation circuit, and the subcode generated by the subcode generation circuit 20 is used as a parity generation circuit 1
9. In this case, in this example, data relating to the frequency characteristics of the magnetic tape is included as the subcode generated by the subcode generation circuit 20. The data on the frequency characteristics may be supplied from the system controller 25 of the VTR, or may be supplied from a subcode detection circuit 46 described later.

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

Then, the digital data output from the mixer 15 is supplied to the modulation circuit 21 to perform modulation for recording. Then, the modulated digital data is supplied to the mixer 22, and a pilot signal for ATF (automatic track following control) obtained at the terminal 23 is synthesized. Then, the digital data output from the mixer 22 is supplied to the equalizer 24 to perform equalization suitable for the recording characteristics of the magnetic tape. In this case, in this example, the equalizer 24 has its equalization characteristics controlled by the system controller 25 so that various equalization characteristics can be selected. And the equalizer 24
Are supplied to recording magnetic heads 3 and 4 attached to a rotary head drum via recording amplifiers 26 and 27 and a rotary transformer (not shown), and are recorded on the magnetic tape 2. In this case, the magnetic heads 3 and 4 is equivalent to the mounted on the rotary head drum the preceding head H _L and the following head H _T to be described later.

Next, the configuration of the reproducing side will be described. The signals reproduced from the magnetic tape 2 by the reproducing magnetic heads 5 and 6 other than the recording magnetic heads 3 and 4 are transmitted to a rotary transformer (FIG. (Not shown) and supplied to the equalizer 33 via the reproducing amplifiers 31 and 32, and the equalizer 33 restores the original signal. 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 supplies the PLL circuit 3
6 performs demodulation in synchronization with the clock detected from the reproduction signal. Further, the reproduction data demodulated by the demodulation circuit 35 is supplied to the time base collector 37, and the time base collector 37 corrects the time axis in synchronization with the clock detected by the PLL circuit 36 to remove the time axis fluctuation component. I do.
Then, the reproduction data output from the time base collector 37 is supplied to error correction circuits 38 and 39, the error correction circuit 38 corrects the error of the video data (digital video signal) in the reproduction data, and the error correction circuit 39 reproduces the data. Error correction of audio data and subcode in data is performed.

The digital video signal output from the error correction circuit 38 is supplied to a digital video processing circuit 40, where the digital video signal is subjected to a predetermined digital signal processing to convert the digital video signal having the data structure for recording into the original digital video signal. Convert. Then, the digital video signal output from the digital video processing circuit 40 is supplied to a digital / analog converter 41 to be converted into an analog video signal, and the converted analog video signal is supplied to an output terminal 42.

The audio data output from the error correction circuit 39 is supplied to a digital audio processing circuit 43, which performs predetermined digital signal processing, and converts the digital audio signal having the data structure for recording into the original digital audio signal. I do. Then, the digital audio signal output from the digital audio processing circuit 43 is converted into a digital / analog converter 44.
And converts the analog audio signal into an analog audio signal, and supplies the converted analog audio signal to the output terminal 45.

The sub-code output from the error correction circuit 39 is supplied to a sub-code detection circuit 46, and the contents of the sub-code reproduced and reproduced by the sub-code detection circuit 46 are determined. Then, when there is data on the frequency characteristics of the magnetic tape among the determined data, the data on the frequency characteristics is supplied to the subcode generation circuit 20, the system controller 25, and the equalizer 33.

In the figure, reference numeral 34 denotes a frequency characteristic measuring circuit.
32 output signal is supplied, and the magnetic tape 2
Measure the frequency characteristics of

The output signals of the reproducing amplifiers 31 and 32 are supplied to an ATF circuit 46, and a tracking error signal is generated from the level of the beat component of the reproduced pilot signal. Supply to servo circuit.

A display unit 28 such as a liquid crystal display is connected to the system controller 25. Based on the data on the frequency characteristics determined by the subcode detection circuit 46, the frequency characteristics of the magnetic tape being recorded / reproduced are read. (Or an equalization amount corresponding to this frequency characteristic) is displayed on the display unit 28 in characters, graphics, or the like.

Here, the magnetic head used in the VTR of this embodiment is
Of heads 3, 4, 5, 6 on the rotating head drum
This will be described with reference to FIG. 2. In FIG.
1 shows a head drum.
Air tape 2 is wrapped around the 180 °
Magnetic head H with different angles_LAnd H_TMounting in close proximity
One set of double azimuth heads (first double azimuth
Head). At this time, the leading head H_LAnd after
Row head H_TGL, and the preceding head H_L
And the following head H_TIs the height direction for one track pitch
(The rotation axis of the ram). And further
At 180 ° to the first double azimuth head.
Position with another set of double azimuth heads (second dub
Luazimas head). This second double door
Jimas head is similar to the first double azimuth head
Leading heads H with different azimuth angles_L´ and the following
H_T′, And their positional relationship is also the first
Same as double azimuth head (ie, interval GL, step 1
Rack pitch). Note that both leading heads H_L,
H _L′ Have the same azimuth angle, and both trailing heads H_T, H
_T′ Is the same. And in this example
Is the preceding head constituting the first double azimuth head
H_L, Following head H_TTo the magnetic head for recording shown in FIG.
3 and 4 to form the second double azimuth head
Leading head H_L', Trailing head H_T′, As shown in FIG.
The raw magnetic heads 5 and 6 are used.

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

FIG. 3A shows an 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. The shaded area is a margin or IBG (interblock gap) where no data is recorded. In the preamble or postamble, for example, a pulse signal having a frequency equal to the bit frequency of data is recorded, so that a PLL provided on the reproducing side for extracting a bit clock is easily locked.

An ATF is provided at the end of one track on the head entry side.
Is recorded. The encoded video data and audio data are recorded in the next section. Further, a recording section for only audio data is provided after the video and audio sections. Then, the sub data (sub code) 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, next, a sync block SB for identifying the block is located, and next, ADR
A threshold value THR for determining the number of allocated bits of C is located. The subsequent block address BA is for an address on the screen. In addition, NEXT
Indicates the length of the block. The encoded data generated by the ADRC includes a dynamic range DR 'and a minimum value MI.
N ', a set of code signals corresponding to each pixel BPL. Also, audio data is
It is inserted in a section separated from the image data. The parity of the error correction code is arranged at the end of the sync block. The array of sync blocks shown in FIG. 3B is an example, and a sync block of a data array (not shown) is also used in consideration of the amount of video data, the amount of audio data, and the amount of parity data.

The recording section of only audio data and the recording section of sub data have the same data arrangement as described above. FIG. 3C shows a data array of sync blocks in a sub data section.

At the head, a block synchronization signal indicating the start of a block is located, an ID signal is located next, and sub data (sub code) is located next. In this example, data relating to the frequency characteristics of the magnetic tape is recorded in a part of the sub data recording area. The parity of the error correction code is arranged at the end of the sync block. The ID signal includes a code for identifying a sub data area, a start ID, a frame ID, a track address, a skip ID, a program number, a block number, and the like. This ID signal is required not only at the time of normal reproduction but also at the time of restoring an image using reproduced data at the time of high-speed reproduction.

Next, the operation of recording and reproducing with the VTR constructed as described above will be described focusing on the control of the equalizer. First, the operation mode of the equalizer set by the VTR will be described. In this example, two types of modes, a reference mode and an auto mode, can be set, and the system is operated by operating a predetermined key (not shown). One of the modes is set in the controller 25. In the reference mode, the equalizing amounts of the equalizers 24 and 33 are set to standard values.

In the auto mode, each equalizer 2
The equalization amounts of 4, 33 are automatically adjusted to optimal values. The adjustment state in the auto mode will be described below. First, at the time of recording, for example, when an unrecorded magnetic tape 2 on which no signal is recorded is used as the magnetic tape 2 to be recorded, the equalizer 24 is equalized by the control of the system controller 25. The amount is initially set to a standard value. In this state, the video signal obtained at the input terminal 11 and the audio signal obtained at the input terminal 16 are recorded on the magnetic tape 2 as digital data. At this time, the system controller 25 supplies the data relating to the frequency characteristics of the magnetic tape corresponding to the currently set equalization amount to the subcode generation circuit 20 and causes the magnetic tape 2 to record this data in the subcode.

In this embodiment, since the reproducing magnetic heads 5 and 6 are provided separately from the recording magnetic heads 3 and 4, reproduction can be performed simultaneously with recording, and signals recorded by the magnetic heads 3 and 4 can be obtained. Is immediately reproduced by the magnetic heads 5 and 6. Then, the frequency characteristic measuring circuit 34 measures the frequency characteristic of the magnetic tape 2 from the reproduced signal at this time. Then, the measurement result is supplied to the system controller 25, and it is determined whether the equalization amount currently set by the system controller 25 is appropriate. At this time, when it is determined that the currently set equalization amount is appropriate, the recording process based on this equalization amount is performed continuously. When it is determined that the currently set equalization amount is not appropriate, the equalization amount of the equalizer 24 is gradually changed from a standard value, and the equalization amount that can be determined to be appropriate from the measurement result of the frequency characteristic measurement circuit 34. Thereafter, recording is performed with this equalization amount. At this time,
Following the change in the equalization amount, the subcode generation circuit 2
The value of the data relating to the frequency characteristic of the magnetic tape in the subcode generated at 0 is also changed.

When a new video signal or the like is to be recorded on the magnetic tape 2 on which a certain signal has already been recorded, the previously recorded signal is reproduced first, and the sub-code contained in the reproduced signal is reproduced. Is detected by the subcode detection circuit 46. Then, data relating to the frequency characteristics of the magnetic tape included in the detected subcode is supplied to the system controller 25, and the equalizer 24 of the recording system is set to a corresponding equalization amount, and recording of a new video signal or the like is performed. Let it be done with equalization amount. Further, data relating to the frequency characteristics of the magnetic tape 2 included in the subcode detected by the subcode detection circuit 46 is supplied to the subcode generation circuit 20 so that the data is recorded on the subcode which is simultaneously recorded when a new signal is recorded. Then, data relating to the same frequency characteristics as those reproduced is added. In addition,
Even if a new signal is recorded on a magnetic tape on which a signal has already been recorded, if there is no data recorded on the frequency characteristics of the magnetic tape in the subcode, the case where the unrecorded tape described above is used Do the same.

At the time of reproduction, the equalization amount of the reproduction system equalizer 33 is set by the data relating to the frequency characteristics of the magnetic tape included in the subcode detected from the reproduction signal of the magnetic tape 2, and the reproduction is performed with this equalization amount.

As described above, the equalization amount of the equalizers 24 and 33 at the time of recording and reproduction is automatically set, so that the optimum equalization amount suitable for the characteristics of the magnetic tape 2 is always set. Mounted magnetic tape 2
Recording / playback is performed by making the best use of the characteristics of. Therefore,
This VTR can perform good recording and reproduction using magnetic tapes having various characteristics.

In the above-described embodiment, only the equalization amount of the equalizer is changed. However, if it is better to change the characteristics of other circuits depending on the characteristics of the magnetic tape, the other circuits are similarly changed. The characteristics of the circuit may also be changed based on the data on the frequency characteristics recorded in the subcode.

[0034]

According to the present invention, the optimum adjustment state of the processing circuit can be determined from the data on the frequency characteristic of the magnetic tape included in the subcode, and the recording system circuit and the reproduction system circuit are always adjusted to the optimum state. This makes it possible to always record and reproduce optimal signals using magnetic tapes having various characteristics.

[Brief description of the drawings]

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

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

FIG. 3 is an explanatory diagram illustrating a data configuration according to an embodiment;

[Explanation of symbols]

 Reference Signs List 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 24 equalizer 25 system controller 28 display unit 33 equalizer 34 frequency characteristic measurement circuit 42 Analog video signal output terminal 45 Analog audio signal output terminal 46 Subcode detection circuit

Claims (1)

(57) [Claims] 1. A VT for recording a video signal on a magnetic tape and adding a subcode to the video signal for recording.
R, at the time of recording, measuring a frequency characteristic of the magnetic tape, and recording data relating to the measured frequency characteristic as the subcode.
TR.