JPS61196472A - Rotating head type recording or reproducing device - Google Patents

Abstract

PURPOSE:To effectively detect that a digital information signal is stored by providing a means for comparing a data error generating probability of the digital information signal picked up by a rotating head with a prescribed probability. CONSTITUTION:A recording condition discriminating circuit 35, by the use of a reproducing output of a head 3 and an output of a CRCC condition discriminating circuit 37, discriminates whether an audio signal is recorded in respective areas, a video signal is recorded and further not recorded. A signal A is a pulse signal to an area where the head 3 reproduces a PCM audio signal and a signal V is a pulse signal to an area where the head 3 reproduces a video signal. By these pule signals, whether the audio signal and the video signal are reproduced from which area may be discriminated by using a window pulse.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a rotary head type recording or reproducing device, and in particular to recording or reproducing a digital information signal using a rotary head in a region extending in the longitudinal direction of a tape-shaped recording medium. The present invention relates to a device that performs playback.

(#Seiyangon no Masu 111) In recent years, high-density recording has been pursued in the field of magnetic recording, and video tape recorders (VTRs) are also trying to reduce the running speed of the tape and perform even higher-density magnetic recording. It has become. Therefore, if audio signals were recorded using a fixed head as in the past, the relative speed could not be kept high and the reproduced sound quality would deteriorate. One solution to this problem is to make the length of the track formed by the rotary head longer than before, and to sequentially record time-base compressed audio signals on the extended portion.

For example, in a rotating two-head helical scan type VTR, the magnetic tape was conventionally wound around the rotating cylinder by more than 180 degrees;
θ) A VTR has been devised that records an audio signal converted into PCM and time-axis compressed in the excess winding portion. Fig. 2 is a diagram showing the tape running system of such a VTR, and Fig. 3 is a diagram showing the recording locus on the magnetic tape by the VTR shown in Fig. 2. In Fig. 0, 1 is the magnetic tape, and 2 is the rotating cylinder. , 3.4 are heads having mutually different azimuth angles that are attached to the cylinder 2 with a phase difference of 1800, 5 is a video area portion of a track formed on the tape 1, and 6 is an audio area portion.

Video area 5 is 180" of rotating cylinder 2 and head 3
．． 4 is the portion where the tape was traced, and audio area 6 is the portion where the head 3.4 traced the tape at 00 minutes of the rotary cylinder 2. In addition, f and ~f4 in FIG. 3 indicate the frequencies of tracking pilot signals superimposed on each track using the well-known four-frequency method, and the frequency relationship is (f2-fl)" f3 f a '= f □
, where fH indicates the horizontal scanning frequency of the video signal.

The sound quality when playing back the audio signal which has been converted into PCM and time axis compressed in the audio area in this way is quite high and is comparable to the sound quality of an audio dedicated device that records and plays back analog signals.

On the other hand, a proposal has been made to record another audio signal in the video area 5 of the above-mentioned VTR. That is, for example, when θ=36, if the rotary head rotates by 180 degrees, the audio area 6 will be expanded to 5 other areas.
There will be one. By recording time-base compressed audio signals independently in each area, an audio-only tape recorder capable of recording a total of six channels of audio signals can be obtained.

Hereinafter, this tape recorder will be briefly explained. FIG. 4 is a diagram showing the tape running system of the above-mentioned tape recorder, and FIG. 5 is a diagram showing the recording locus on the tape by this tape recorder. Note that the numbering is the same as in FIGS. 2 and 3.

In FIG. 5, CHI to CH6 are audio signals during the period when head 3 or head 4 is tracing from A to B, B to C1C, D to E, E to F, and F to G in FIG. This is the area where is recorded. It is possible to record audio signals separately in each area, and so-called azimuth overwriting is performed in each area, but the tracks in each area CHI to CH6 do not need to be on the same straight line, and each area Pilot signals for tracking control are recorded in each region, but it is assumed that they are recorded in a predetermined rotation (ft→f2→f3→fa) for each region, and there is no correlation between the regions.

Further, the area indicated by CHI-CH3 is recorded and reproduced when the tape 1 is running at a predetermined speed in the direction indicated by arrow 7 in FIG. 3, and the area indicated by CH2-CH2 is similarly recorded by arrow 9.
Recording and playback are performed when the vehicle is traveling in the direction shown. Therefore, as shown in FIG. 5, the slope of each track in the area CHI to CH3 is slightly different from the slope of each track in the area CH2 to CH2. However, regarding the difference in relative speed at this time, compared to the difference due to the rotation of heads 3 and 4, tape 1
The water-based components are extremely small and should not be a problem.

Figure 6 shows the recording and playback time of the tape recorder as described above.
"The phase detection pulse (
PG), “high level (H)” and “
It is a 30 Hz rectangular wave that repeats a low level (L). Also, (b) is a PG with the opposite polarity to PG (a).

Here, PG (a) is H while head 3 rotates from B to G in Figure 4, and PG (b) is H while head 4 rotates from B to G in the same way.
It is assumed that the state is H during the rotation.

Figure 6 (C) is the data reading pulse obtained from PG (a), which corresponds to one field of the video signal (1/60 second).
This is for sampling the audio signal every other field in the period corresponding to the period corresponding to the period.

In FIG. 6(d), H indicates the signal processing period for adding redundant code for error correction or changing the arrangement of one field of sampled audio data using a RAM, etc. Figure 6(e) shows the data recording period H.
, which indicates the timing at which the recording data obtained by the above-described signal processing is recorded on the tape 1.

For example, if we follow the flow of the signal in time using Fig. 6, t
Data sampled during a period of tNts (while head 3 is moving from B to G) is from t3 to t5 (when head 3 is moving from G to A)
Signal processing is performed at t5 to t6 (head 3 is A-B)
recorded over a period of That is, C in FIG.
Recorded in the HI area. On the other hand, data sampled while pc(b) is H is signal-processed at the same timing and recorded in the CHI area by the head 4.

PG (a) at a predetermined phase (here, 36° for one region)
The phased PG is shown in Figure 6(f), hereinafter referred to as PG (f)
A case will be described in which an audio signal is recorded using a PG (not shown) having the opposite characteristics. Figure 6 t2-t4
The sampled data is subjected to signal processing according to the signal shown in FIG. 6(g) during t4 to t6, and recorded according to the signal shown in FIG. 5(h) during t6 to t7. That is, data is recorded by the head 3 in the area indicated by CH2 in FIG. 5 during the period when the head 3 traces B to C. The data sampled during the period t4 to t7 is recorded by the head 4 in the area indicated by CH2.

Next, the operation of reproducing the signal recorded in the area indicated by CH2 will be explained.

The reading of data on one tape by the head 3 is shown in Figure 6 (
t6 to t7 (same for tl to t2) according to the signal shown in h)
t7 to t8 (
From t2 to t3), signal processing opposite to that during recording is performed. That is, error correction and the like are performed during this period, and a reproduced audio signal is output from t8 to t9 (t3 to t6) in accordance with the signal shown in FIG. 6(j). Of course, the reproduction operation by the head 4 is performed with a phase difference of 180 degrees from the above-mentioned operation, and thus a continuous reproduction audio signal is obtained.

It goes without saying that for the other channels CH3 to CH6, it is sufficient to phase PG(a) by n x 36 degrees and perform the above-mentioned recording/reproducing operation based on this. Direction independent.

In this way, the VTR can be used as a dedicated multi-channel audio device.
can be used.

<Problems to be Solved by the Invention> Although it is possible to record extremely long audio signals with the above-mentioned device, on the other hand, there is a high possibility of erroneous operation if the recording situation is not grasped. , there are recorded and unrecorded parts of the audio signal for each channel, and a video signal may also be recorded on CH2-CH2, and there is also an unerased part of the video signal. Therefore, it is difficult to accurately determine the recording status.

Moreover, if a video signal is mistakenly recorded on such a recording medium, all audio signals from CH2 to CH2 will be erased.

Also, CH2-CH2 is added to the medium on which the video signal is recorded.
If an audio signal is recorded on even one channel, the video signal itself becomes invalid.

Therefore, it is possible to determine the recording status of each area, but it is difficult to determine whether the recorded signal is a digital audio signal or a video signal. However, it is not preferable to separately record an identification signal for this judgment because it will interfere with high-density recording, and if the identification signal is superimposed on the digital audio signal and recorded, the recording of the digital audio signal will be interrupted. The error rate during playback increases.

In view of the above-mentioned problems, the present invention provides a rotation method that can reliably determine that a digital information signal is recorded in an area extending in the longitudinal direction of a tape-shaped recording medium without recording a special signal. The purpose of the present invention is to provide a head type recording or reproducing device.

<Means for Solving the Problems> In view of the above problems, the present invention provides means for comparing the data error occurrence probability of the digital information signal picked up by the rotary head with a predetermined probability.

<Function> By using the output of the above-mentioned comparison means, it has become possible to reliably detect that a digital information signal is recorded.

<Embodiment> FIG. 1 is a diagram showing a schematic configuration of a tape recorder as an embodiment of the present invention. Components in FIG. 1 that are similar to those in FIGS. 2 to 5 are given the same numbers.

PG obtained from the rotation detector 11 of the rotating cylinder 2 is supplied to the cylinder motor control circuit 15.

The cylinder 2 is rotated at a predetermined rotation speed and a predetermined rotation phase. 12 is the flywheel 14 of the capstan 13
The output of the rotation detector 12 is supplied to a capstan motor control circuit 25, which controls the capstan 13 to a predetermined rotation speed during recording.

On the other hand, the above-mentioned PG is supplied to the window pulse generation circuit 16. FIG. 7 is a timing chart for explaining the phase relationship between the window pulse and the gate pulse with respect to PG.

FIG. 7(a) shows PG, which is at a high level while the head 3 is moving from point B to point G in FIG. Figure 7 (b
) to (g) are window pulses indicating the recording/reproducing timing of each area CHI to CH'6, respectively. In FIG. 7, the solid line is for head 3, and the dotted line is for head 4.
It is about.

By manually operating the operation unit 1B, an operation mode such as recording and reproduction, and an area to be recorded and reproduced are specified. This data is supplied to the system controller 27, which controls each part of the device.

The region designation circuit 19 supplies region designation data to the gate pulse generation circuit 17 to obtain a desired gate pulse. Note that when a video signal recording or playback command is issued using the operation unit 18, the area specifying circuit 19 automatically specifies CHI based on the output of the system controller 27.

The control gate pulse of the gate circuit 20 is applied to the head 3 based on the area designation data. For each head 4, the aforementioned window pulses (shown in FIGS. 7(b) to 7(g)) are selectively supplied. Now, if the area shown in FIG. 5 CH2 is designated, the gate circuit 20 is designated as shown in FIG.
) is controlled by the window pulse shown in ).

During recording, the analog audio signal input from the terminal 21i is supplied to the PCM audio signal processing circuit 22,
The signal is sampled by the circuit 22 at the above-described timing related to the window pulse (C), converted into digital data, and then subjected to the above-described signal processing. The recording audio data obtained in this way is combined with the tracking pilot signal generated by the pilot signal generation circuit 23 in a rotation of f1 → f2 → f3 → f4 for each field and the adder 2.
4 is added. The output of the adder 24 is appropriately gated by the gate circuit 20 as described above, and written into the area CH2 by the head 3.4.

During playback, the playback signal from the head 3.4 is also supplied to the lobal filter (LPF) 25 and the PCM audio circuit 22 via the gate circuit 20 using the window pulse (C). In the PCM audio circuit 22, signal processing such as error correction, time axis extension, and digital-to-analog conversion is performed in the opposite direction to recording, and a reproduced analog audio signal is output from the terminal 21o.

The ATF circuit 26 is a circuit for obtaining a tracking error signal using a well-known four-frequency method, and uses a reproduced tracking pilot signal and a pilot signal generated by the pilot signal generation circuit 23 in the same rotation as during recording. As is well known. However, in this case, since tracking is performed on the area specified by the area specifying circuit 19, the tracking error signal must be sampled and held during the period when the head 3.4 is tracing the specified area. Incidentally, when a video signal is also recorded and reproduced at the same time, a tracking error signal is obtained using a conventional method.

The tracking error signal thus obtained is supplied to the motor control circuit 15, which controls the running of the tape l during playback via the capstan 13, thereby performing tracking control.

Hereinafter, recording and reproducing of a video signal when recording and reproducing of a video signal is instructed will be explained. The video signal inputted from the terminal 28i is subjected to well-known signal processing in a video signal processing circuit 29, added to a tracking pilot signal in an adder 31, and recorded via a post-gate circuit 30. The gate circuit 30 is controlled by the PG, and the video signal is sequentially and continuously recorded by the head 3.4. The video signal reproduced from the head 3.4 is converted into a continuous signal by the gate circuit 30 and inputted to the video signal processing circuit 29. In the video signal processing circuit 29, the reproduced video signal is returned to its original signal form. At the same time, the reproduced pilot signal is supplied to the ATF circuit 26 to obtain a tracking error signal. Since this tracking error signal is a continuous signal, there is no need for sampling and holding, and it is supplied to the capstan motor control circuit via the LPF.

37 is a CRC corresponding to the detection means and comparison means of the present invention.
A C state determination circuit that detects whether an error exists in each data block of a PCM audio signal using a well-known CRCC check code, and determines whether the block error rate is larger or smaller than a predetermined error rate. Determine whether

CRC is used in PCM audio signals to detect or correct errors added on the recording medium during playback.
A cyclic code called C is added in advance to the recorded data. This CRCC records the recorded data of the PCM audio signal corresponding to the time of one field of the video signal, for example, in the NTSC system, 132 blocks, C
In the CIR method, the information is divided into 157 blocks and added to each block.

This CRCC is calculated as "0" as the CRCC operation result when no error is added to the reproduced data, and as data other than "0" when an error is added. The calculation method of CRCC is originally determined so that the probability of false detection due to the addition of errors is extremely low. Therefore, it can be asserted with an extremely high probability that the data string for which the CRCC calculation result is "θ" matches the data string at the time of recording. Furthermore, if the i-minute video signal, which has a wide spectrum width different from the original data string, is converted into PCM.
The possibility that this is input to the reproduced signal processing circuit and erroneously detected as a correct data string is further reduced.

FIG. 8 is a diagram showing a specific example of the CRCC state determination circuit shown in FIG. 1, in which 90 is an amplifier for amplifying the RF signal reproduced from the head 3, and 91 is a waveform equalization circuit. 92 is a circuit that extracts a clock component from the output of the PCM audio signal obtained from the waveform equalization circuit 91; 93 is a clock regeneration circuit that newly generates a control clock based on the extracted clock component; and 94 is a circuit that generates a new control clock based on the control clock. a bit synchronization circuit for restoring each bit of data, 9
5 is a synchronization signal detection circuit, and 96 is a well-known CRCC calculation circuit.

Since the CRCC operation result is usually valid data only at the final bit of the CRCC check point of the input data, a latch pulse indicating this timing is generated using the above-mentioned synchronization signal and the above-mentioned control clock. Assuming that "θ" is output when there is no error as a result of the CRCC operation, this is gated by the logic gate 98 with a latch pulse, and the counter lo
supply to t. The counter 101 counts up each time information indicating that there is no error is input, and if no error occurs in any data block, the counter 101 counts up to, for example, 132 in the NTSC system and 157 in the CCIR system. The reset pulse generation circuit 106 operates based on the PG, and the counter 101 is reset by a reset pulse generated by the reset pulse generation circuit 106 each time the head 3 enters each area.

On the other hand, the data generation circuit 102 outputs predetermined data, for example, 30. In the CCIR method, about 40 pieces of data are generated, and when the counter 101 counts up more than this data, the digital comparator 103
generates an H output. Incidentally, here, 6 of the counter 101
It is also possible to replace this digital comparator with an OR gate that outputs H if any of the data after the bit is "1". This time is equivalent to the case where the output data from the data generation circuit 102 is set to 32.

The sampling pulse generation circuit 104 generates sampling pulses based on the PG at a predetermined timing while the head 3 is tracing each of the aforementioned regions (here, the timing at which the head 3 traces the center of each region). This sampling pulse is gated in the sampling circuit 105 by the output of the digital comparator 103, and is 0UTl
is output as Note that this sampling pulse itself is output as 0UT2. Here, if a sampling pulse is output at 0UTI, it can be determined that a PCM audio signal is recorded in the area, and if it is not output, it can be determined that a PCM audio signal is not recorded.

35 is a recording state determination circuit, and this circuit 35
Whether an audio signal is recorded in each area using the playback output of and the output of the above-mentioned CRCC state determination circuit 37
It discriminates whether the video signal is recorded or not.

FIG. 9 is a diagram showing an example of a specific configuration of the recording state determination circuit. 40 is OUT 1 of the CRCC state determination circuit 38
．． 41 is the reproduction output signal of the head 3, and 45 is 0 of the circuit 38.
The reproduced output signal of the head 3 is supplied to the LPF 42 at the terminals to which the UT2 is respectively supplied. The LPF 42 is for extracting the RF signal component from the reproduced signal, and after being detected by the RF multiplied signal detection circuit 43, it is compared with a predetermined voltage (vth) by the comparison circuit 44. Therefore, the output of the comparison circuit 44 becomes high level (H) when the head 3 traces the portion where the video signal or PCM audio signal is recorded.

On the other hand, the above-mentioned sampling pulse inputted from the terminal 45 is delayed by a minute time in the delay circuit 46, and then supplied to the AND gate 47 and gated by the output of the above-mentioned comparison circuit 44. Of the delayed sampling pulses output from the AND gate 47, those in the PCM audio signal recording area are muted by the AND gate 48. That is, the monomulti 57 is triggered by the sampling pulse of the PCM audio signal recording area, and the inverter 58 becomes L during the period including the timing at which the AND gate 47 outputs the sampling pulse.

Therefore, the signal indicated by A in the figure is a pulse signal for the area where the head 3 is reproducing the PCM audio signal, and the signal indicated by ▪ is the pulse signal for the area where the head 3 is reproducing the video signal. From these pulse signals, it is possible to determine from which area the audio signal and video signal are being reproduced using the window pulses described above.

Window pulses corresponding to CHI to CH6 are supplied to AND gates 51 to 56, and when a reproduced audio signal is obtained from a certain area, the AND gate corresponding to that area is applied once every rotation of the rotating head 3. Outputs H. On the other hand, the window pulses corresponding to CH2 to CH6 are supplied to AND gates 62 to 66. Similarly, when a reproduced video signal is obtained from a certain area, the AND gate corresponding to that area is Outputs H once. Here, it is assumed that no video signal is recorded or reproduced on the CHI.

Monomulti (MM) 71 to 76 and 82 to 86 are for holding the output signals of each AND gate 51 to 56 and 62 to 66, and the holding period of H can be retriggered at a rotation period of the head 3 or more. shall be taken as a thing. Therefore, the area where the audio signal is recorded in CH2-CH2 is CH2-CH2 in Figure 8.
This can be determined by the terminals I to CH6 becoming H. Also, the area in CH2-CH2 where the video signal is recorded can be determined by looking at the outputs of MM82-86, but since the video signal is valid only after it is recorded in all CH2-CH2, these It can be determined whether or not a valid video signal is being recorded by the logical sum of the outputs of the MMs 82 to 86. In other words, when the output of the AND gate 49 is H, it means that a valid video signal is being recorded.

The output of this discrimination circuit 35 (CHI to CH6 and V[DE
O) is displayed on the display 36.

According to the above-described apparatus, it has become possible to reliably confirm whether or not a digital audio signal is recorded on each channel without superimposing an identification signal.

In the above embodiment, PCM is used as the digital information signal.
Although the present invention has been described using an example of an audio signal, the present invention is not limited to this, and the present invention can be applied to, for example, a DigiMole image signal, a single character signal, etc., with great effect.

Further, since the portion indicated by 100 in the above-mentioned CRCC state determination circuit 38 is normally provided in the PCM audio signal reproduction processing circuit, it is also possible to configure the system to use this circuit. However, since this circuit is for generating audio signal playback output in l-field period units, and the CRCC calculation circuit is also configured to operate only in a specific area, the method of supplying the control clock must be changed. By changing this, it becomes possible to determine the recording status for all areas in one revolution of the head 3. However, if the head 3 is rotated six times, this concern can be eliminated, as explained above, according to the present invention, the rotary head type recording or reproducing device can reliably determine the recording status of the digital information signal without using any special signals. I was able to get

[Brief explanation of drawings]

Fig. 1 is a diagram showing a schematic configuration of a tape recorder as an embodiment of the present invention, Fig. 2 is a diagram showing a tape running system of a conventional VTR, and Fig. 3 is a diagram showing the magnetic tape by the VTR shown in Fig. 2. , L is a diagram showing recording trajectories. FIG. 4 is a diagram showing a tape running system of a multi-channel tape recorder, and FIG. 5 is a diagram showing a recording locus on a magnetic tape by the tape recorder shown in FIG. 4. Fig. 6 is a time chart of recording and reproduction of the tape recorder shown in Fig. 4, Fig. 7 is a timing chart for explaining the phase relationship of the window pulse with respect to PC, and Fig. 8 is a diagram of the CRCC status determination circuit in Fig. w41. A diagram showing a specific example. FIG. 9 is a diagram showing a specific example of the recording state discriminating circuit in FIG. 1. 1 is a magnetic tape as a recording medium, 3 and 4 are rotary heads, 22 is a PCM audio signal processing circuit, 35 is a recording state determination circuit, 38 is a CRCC state determination circuit, 96 is a CRCC calculation circuit, and 101 is a counter. , 103 are digital comparators, and CHI-CH6 are regions extending in the longitudinal direction.

Claims (1)

[Claims] An apparatus for recording or reproducing a digital information signal using a rotating head in a region extending in the longitudinal direction of a tape-shaped recording medium, the apparatus comprising means for detecting data errors in the digital information signal picked up by the rotating head. . A rotary head type recording or reproducing apparatus, comprising means for comparing an error occurrence probability during a period when the head is crossing the area with a predetermined probability based on the detection means.