JPS63244366A - Magnetic recording and reproducing system - Google Patents

Abstract

PURPOSE:To automatically prevent the generation of a strange sound at the joint of audio signals by starting to record the signal to be recorded,or setting a pause mode or a stop mode, after a PCM audio signal corresponding to 0 level is recorded in a prescribed frame. CONSTITUTION:A control circuit 40 controls respective circuits and means and so on, correspondingly to an input from an inputting means 41, and makes them execute prescribed operations. When a record mode is inputted, before the signal to be recorded is recorded, the PCM audio signal corresponding to 0 level is automatically recorded and the recording of the signal to be recorded is executed subsequently. Besides, at the time of the recording mode, when the pause mode or the stop mode is inputted, the PCM audio signal corresponding to 0 level is recorded automatically in the prescribed frame, and the pause mode or the stop mode is executed after the said recording is finished. Thus, the generation of a noise at the joint can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing method suitable for use in a magnetic recording/reproducing apparatus typified by R-DAT.

[Summary of the invention]

In the present invention, a predetermined frame of a PCM audio signal corresponding to the 0 level is automatically recorded immediately before recording a recording signal or immediately before executing a pause mode or stop mode in the recording mode.

[Conventional technology]

In the R-DAT, information is recorded and reproduced by winding a magnetic tape approximately 90 degrees around a rotating drum on which one rotary heads A and B are mounted 180 degrees apart from each other. 90
A PCM audio signal (PCM) is recorded approximately in the middle of the track corresponding to the angle of degrees, and subcode signals (SUB-1°5UB-2) are recorded before and after it. Furthermore, tracking signals fl to f (ATF signals) are recorded between the subcode signal and the PCM audio signal. fl is a pilot signal (130KHz).

f, is the synchronization signal (522 KHz) of the track (track A) traced by rotary head A, and fl is the synchronization signal (522 KHz) of the track traced by rotary head A.
f4 is a synchronization signal (784 kHz) of a track (track B) traced by rotating head B with an azimuth different from that of , and f4 is an erasure signal (1.5 MHz).

The tracking error signal includes a pilot signal f1 (crosstalk component) that is regenerated from the right track when synchronization signal f2 or f3 is detected, and a pilot signal f1 (crosstalk component) that is regenerated from the left track after a predetermined time has elapsed after detection. It is generated from the level difference between.

[Problem that the invention seeks to solve]

By the way, the recorded audio signal is digitized (P
CM), and is subjected to processing such as addition of an error correction code and interleaving, and is temporarily stored in memory. As a result, if recording of a predetermined audio signal is once stopped and then another audio signal is subsequently recorded, the signals may be mixed and noise may occur at the joint.

Therefore, the present invention is intended to prevent noise from occurring at the joint portion.

[Means for solving problems]

In a magnetic recording/reproduction method, the present invention provides for: when a recording mode is input, before recording a recording signal, or when a pause mode or a stop mode is input during a recording mode, before executing a pause mode or a stop mode: The present invention is characterized in that a predetermined frame of a PCM audio signal corresponding to 0 level is recorded, and after the recording is completed, recording of the recording signal is started or a pause mode or a stop mode is set.

[Effect]

When the recording mode is input, a predetermined frame of a PCM audio signal corresponding to O level is automatically recorded before a recording signal is recorded. Recording of the recording signal is then performed. Alternatively, when pause mode or stop mode is input during recording mode, P corresponding to 0 level before the pause mode or stop mode is executed.
A CM audio signal is automatically recorded for a predetermined frame.

Pause mode or stop mode is executed after this recording is finished.

〔Example〕

FIG. 1 is a block diagram when the magnetic recording/reproducing apparatus of the present invention is applied to an R-DAT. A predetermined mode can be input by operating input means 41 having various switches, buttons, etc.

A control circuit 40 comprising a microcomputer or the like controls each circuit 1 means etc. in response to input from an input means 41,
A predetermined operation (for example, recording mode) is executed.

A clock output from an oscillation circuit 9 made of a crystal oscillation circuit or the like is supplied to various circuits including a generation circuit 10. The generating circuit 1o generates a reference signal of a predetermined frequency in synchronization with the clock. The first frequency reference signal is input to the servo circuit 6, and the second frequency reference signal is input to the servo circuit 8 via the switch 12. Detected by the PG double signal detection circuit 17 generated in synchronization with the rotation of the rotating drum 1,
The detection signal is input to the servo circuit 6. The servo circuit 6 also receives an FG multiplied signal. The servo circuit 6 compares these phase servo and frequency servo signals with a reference signal, and controls the rotation of the rotary drum 1 in response to the error signal.

Since the switch 12 is switched to the contact R side in the recording mode, the servo circuit 8 rotates the capstan 5 at a predetermined speed in response to the input reference signal. The rotation of the reel 3.4 of the magnetic tape 2 is controlled by a servo circuit 7. The recording signal (digital data, subcode data, etc.) that has been subjected to necessary processing such as 8/10 modulation and addition of an error correction code by the encoder 16 is amplified by the amplifier circuit 14, and the switch is switched to the contact R side during recording. 1
1 to the rotary heads A, H. The ATF signal is similarly supplied to the rotary heads A and B via the amplifier circuit 14 and the switch 11. The generation circuit 18 is the detection circuit 1
In synchronization with the output of 7, a head switching pulse (HSWP) for switching between the rotary heads A and B is generated and output. The amplifier circuit 14 is controlled by this head switching pulse and supplies its output to the rotating heads A and B alternately.

In this way, PCM digital data, subcode,
ATF signals and the like are recorded on the inclined tracks on the magnetic tape 2.

When the playback mode is input, the switch 11 is switched to the contact P side. Therefore, the reproduction signal output when the rotary heads A and B trace a track is input to the amplifier circuit 13 via the switch 11. The signal amplified by the amplifier circuit 13 is output to the decoder 15. Decoder 1
In step 5, the signal subjected to processing such as 8/10 demodulation, error correction, and error interpolation is D/A converted and then output to a speaker (not shown) or the like.

The equalizer 29 uses a synchronizing signal f out of the output of the amplifier circuit 13.
2. Emphasize the component of f. Zero cross detection circuit 30
detects the zero cross of the output of the equalizer 29, pulses the signal, and supplies it to the detection circuit 31. The detection circuit 31 detects the rotating head A based on the head switching pulse.
If the timing is when B is tracing the magnetic tape, when a signal with the same period as the synchronizing signal f2 is input (when the synchronizing signal f2 is detected), or when the rotating head B is tracing the magnetic tape, synchronization occurs. When a signal with the same period as the signal f□ is input (when the synchronization signal f is detected), a detection pulse corresponding to the edge of the input signal is output to the timing signal generation circuit 32, and a sample is output to the sample hold circuit 21. Output pulse SPI. The timing signal generation circuit 32 generates the sample pulse SP2 when counting a predetermined number of clocks after the detection circuit 31 outputs the signal (two blocks after the sample pulse SPI is generated). The flag circuit 33 is set by this sample pulse SP2. The flag circuit 33 is cleared immediately when the output signal is issued to the control circuit 4o.

The bandpass filter 19 separates the component of the pilot signal f from the output of the amplifier circuit 13. The output of the bandpass filter 19 is input to a detection circuit 20, and its envelope is detected. The sample and hold circuit 21 samples the output of the detection circuit 2o at the timing of the sample pulse SPI and outputs it as a voice. The output of the sample hold circuit 21 and the output of the detection circuit 20 are the differential amplifier circuit 22.
are input, and the difference is calculated. The sample and hold circuit 23 samples and holds the output of the differential amplifier circuit 22 at the timing of the sample pulse SP2. As a result, the sample hold circuit 23 generates and outputs the difference in the output of the detection circuit 2o at the timing of the sample pulses sP1 and SF3, that is, a tracking error signal.

The tracking error signal is input to the servo circuit 8 via the switch 12. The servo circuit 8 controls the rotation of the capstan 5 in response to the tracking error signal. As a result, the tracking states of the rotary heads A and H are controlled.

When the after-recording mode is input, the switch 11 connects the PCM to the contact P side in the ATF recording area.
It is switched to the contact R side in the recording area (when after-recording a PCM signal) or the subcode recording area (when recording a subcode signal).

In other words, the control circuit 40 outputs a logic 0 signal in the recording mode.
Furthermore, a logic 1 signal is supplied to the switch 12 during the playback mode (including during the after-recording mode). This signal is inverted by an inverter 42 and supplied to the switch 11 via an OR gate 43, which causes the switch 11 to have a logic 0
When a logic 1 is supplied, the switch is switched to the contact P side, and when a logic 1 is supplied, the switch is switched to the contact R side. In the after-recording mode, a logic 0 signal is input to the control circuit 4o via the inverter 42 and the OR gate 43, but the timing signal generation circuit 38 inputs the logic 0 signal via the OR gate 43 in the area corresponding to the recording signal to be after-recorded. 1
During this time, the switch 11 is switched to the contact R side.

The timing signal generation circuit 38 is controlled as follows in order to generate such a timing signal. That is, when the detection circuit 17 detects the PG multiplied signal, the initial counter 35 starts counting clocks. When the count value reaches a predetermined value, the flag circuit 36 is set;
The detection circuit 34 is activated. The detection circuit 34 monitors the RF multiplied signal output by the amplifier circuit 13, and detects the rotating head A,
B's touch on the magnetic tape is detected. When the detection circuit 34 detects a touch on the magnetic tape, the counter 37 is activated, starts counting clocks in synchronization with the output of the timing signal generation circuit 32, and generates a timing signal corresponding to the count value. It is output to the circuit 38. The timing signal generation circuit 38 generates a necessary timing pulse when the count value reaches a predetermined value. For example, the counter value from when the timing signal generation circuit 32 outputs a pulse at a predetermined timing in the ATFI region. When reaches a predetermined value, counter 3
7 causes the timing signal generation circuit 38 to generate a timing signal indicating the starting point of setting data to be recorded in the PCM recording area, and outputs it to the encoder 16, control circuit 40, etc. Further, when the count value from when the timing signal generation circuit 32 generates a pulse in the ATF2 area reaches a predetermined value, the counter 37 causes the timing signal generation circuit 38 to generate a timing signal for recording and reproducing subcode 2. . Also, at this time, the timing signal generation circuit 32
The counter 39 starts counting clocks in synchronization with the pulses output by the counter 39.

The counter 39 outputs a signal to the timing signal generation circuit 38 at a timing corresponding to the position of subcode 1 of the next track. At this time, the timing signal generation circuit 38 generates the timing signal of subcode 1.

In addition to the basic circuits and means described above, the present invention is provided with a detection circuit for detecting a pilot signal and a detection circuit for detecting an RF multiplied signal.

The former includes a comparison circuit 24, a counter 25 . Flag circuit 26
The latter is composed of a detection circuit 27 and a flag circuit 28.

The output of the detection circuit 20 is input to a comparison circuit 24 and compared with a predetermined reference voltage V. This reference voltage V is set to a value greater than the level of the pilot signal obtained as a crosstalk component and smaller than the level of the on-track pilot signal.

Therefore, the comparator circuit 24 outputs a logic 1 signal for the period of the pilot signal having a length of two blocks. The counter 25 counts clocks when a logic 1 signal is input from the comparison circuit 24. It is approximately equal to the length of two blocks, but
When the number of clocks corresponding to a slightly shorter period has been counted, the counter 25 outputs an output. The flag circuit 26 is set by this output. That is, when the pilot signal of the track being traced is detected, the flag circuit 26 is set, and its output is sent to the control circuit 40.
supplied to The flag circuit 26 is reset immediately after issuing an output to the control circuit 4o.

On the other hand, the detection circuit 27 monitors the output of the amplifier circuit 13 and
Detecting the presence or absence of a double signal. When the RF double signal is detected, the flag circuit 28 is set, and its output is sent to the control circuit 4.
It is input to 0.

The control circuit 40 monitors the pilot signal and the outputs of the RF multiplier signal flag circuits 26 and 28, and executes the following control. That is, when the recording mode is input from the input means 41, the control circuit 40 first reproduces a predetermined frame (for example, 2 to 4 frames) of the magnetic tape prior to the recording operation. Then, the recording state of the magnetic tape is determined from the output of the flag circuit 26 (or flag circuit 28). If at least one of the PCM audio signal or the subcode signal has already been recorded, the ATF signal is necessarily recorded (the RF multiplied signal is present). Also, if no signal is recorded, the ATF signal is also not recorded (R
F-fold signal does not exist). Therefore, the flag circuit 26 or 2
The recording state of the magnetic tape can be detected from the output of 8.

If some information has already been recorded, the control circuit 4o
automatically (forcibly) enters after-recording mode (
Set the after-recording mode for both PCM data and subcode data. Then, as described above, the PCM audio signal and subcode signal are recorded in each area.

At this time, since the ATF signal is not recorded, the RF multiplied signal of the recorded signal in the normal case becomes as shown in Figure 12 (a), whereas the RF multiplied signal of the recorded signal in this case is shown in the same figure (b).
It becomes as shown in . AT already recorded in this way
If a recording signal is recorded while tracking is controlled by FIG, the tracks in the ATF area and the tracks in other areas will deviate by about 456 points. However, even if the track is shifted in this way, it is possible to reproduce the data.

During operation in the after-recording mode, the output of the flag circuit 26 is monitored, and when no pilot signal is detected from a predetermined number of consecutive tracks (for example, 4 tracks), the control circuit 40 automatically switches the after-recording mode to the recording mode. . After switching to the recording mode, the ATF signal is also recorded at the same time, so the RF multiplied signal of the recorded signal at that time becomes as shown in FIG. 12(a).

When switching from the after-recording mode to the recording mode, four tracks on which no ATF signal is recorded are formed. However, when this magnetic tape is reproduced, the tracking error signal of the previous track is held, so in practice it is possible to reproduce data with almost no problems.

On the other hand, if the tape has no information recorded on it, or if the recorded information ends midway, the recording mode is automatically set. When the tape end is reached in the recording mode or when a stop mode is input by the input means 41, the control circuit 40 controls the servo circuit 7.8,
While stopping the running of the magnetic tape, the encoder 1
6 to cancel the recording mode.

When the pause mode is input from the input means 41, the control circuit 40 controls the encoder 16 to cancel the recording mode and at the same time set the playback mode. Then, a predetermined number of tracks (for example, four tracks) are reproduced, and the recording state of the magnetic tape is checked again from the output of the flag circuit 26 or 28.

When the determination of the magnetic tape is completed, the control circuit 40 controls the servo circuit 7.8 to rewind the magnetic tape by a predetermined number of tracks. Then, the traveling direction is further reversed, the recording mode is set, and a predetermined frame (for example, two frames) of the PCM digital signal corresponding to the O level of the audio signal is recorded. After this recording operation is completed, a pause mode is set and the running of the magnetic tape is stopped.

Thereafter, when the input means 41 is operated and a command to cancel the pause mode is input, the control circuit 40 sets the after-recording mode or the recording mode in response to the detection immediately before setting the pause mode.

The above operation is shown in a flowchart as shown in FIG.

In the above description, the pilot signal f1 is detected, but the recording state of the magnetic tape can also be determined by detecting the synchronizing signal f2 or f3.

FIG. 6 is a block diagram of a circuit for recording a signal corresponding to the 0 level of a PCM audio signal. The input audio signal is A/D converted by the A/D conversion circuit 51 and then written to the memory 52 or 53 alternately via the switch 55. When data is being written to one of the memories 52, 53, it is read from the other via the switch 56. The read data is input to the interleaving circuit 58 via the switch 57 and interleaved. The interleaved data is temporarily stored in the memory 60, and after an error correction code generated by the additional circuit 59 is added thereto, it is read out as recording data.

A counter 61 counts the number of rising and falling edges of the head switching pulse.

Each time the count value changes, the delay type flip-flop 62
Outputs a pulse to. Therefore, the flip-flop 62 outputs a signal having the same period as the head switching pulse.

This signal switches switches 55 and 56, so that memories 52 and 53 alternately repeat write and read operations.

On the other hand, at the timing of recording the O level signal, the control circuit 40 resets the R-S flip-flop 63. Therefore, the O level signal (digital signal) generated by the generation circuit 54 is selected by the switch 57 and output instead of the PCM audio signal. The counter 61 is reset at the same time as the flip-flop 63, and then outputs an output when it counts a predetermined number of edges, causing the flip-flop 63 to be set. As a result, switch 57 again switches to switch 5.
It can be switched to the 6th side.

FIG. 7 is another block diagram of a circuit for recording a 0 level signal. The control circuit 40 switches the switch 57 to the lower side in the figure when recording a 0 level signal, and to the upper side in the figure at other times. The number of frames in which the 0 level signal has been recorded is detected by the count value of the counter 61.

In R-DAT, as shown in FIG. 8(a), a left channel signal and a right channel signal are recorded in the first half and the second half of one track, respectively. When the second recording signal is recorded following the first recording signal as shown in FIG. 2(b),
The two signals may be erroneously mixed, and the waveform of the reproduced signal at the joint may be distorted as shown in FIG.

However, in the present invention, since substantially 0-level PCM audio data is recorded at the joint as shown in FIG. 8(c), there is a possibility that a large abnormal noise may be generated there or damage to the speaker. is prevented.

In the above, a 0 level signal is recorded immediately before setting the Bose mode, but as shown in the flowcharts in Figures 3 and 4, an O level signal is recorded immediately before setting the stop mode or immediately after starting the recording mode. You may also do so.

If it is necessary to more accurately detect the recording position of a PCM audio signal, subcode signal, ATF signal, etc., the operation shown in the flowchart of FIG. 5, for example, can be performed.

That is, when the recording mode is input from the input means 41, the control circuit 40 records a predetermined frame (for example, 4 to 8 frames) of an O-level PCM audio signal before recording the original PCM audio signal. At this time P
A subcode signal accompanying the CM audio signal is automatically recorded.

After the recording is completed, the magnetic tape is rewound by the recorded amount by the servo circuit 7.8, reversed in the forward direction, and reproduced.

When the rotating drum 1 generates two PG multiplied signals (FIG. 10(a)) during one rotation, the output of the reproducing operation detecting circuit 17 is monitored, and when one of the PG multiplied signals PGl) is detected. The control circuit 40 starts a built-in timer (
Same figure (C)). The control circuit 40 then controls the decoder 15 to detect subcode 1 (FIG. 10(b)).

The value of the timer when subcode 1 is detected is stored in the built-in memory. A similar operation is performed on the other PG multiplied signal P.
O2) is also performed. This stored value is obtained as a result of actually recording data and reproducing it, so it accurately corresponds to the data recording position.

Therefore, the recording positions (timings) of the recording signals of the rotary heads A and B are corrected in accordance with each stored value.

When the rotary drum 1 generates one PG signal (FIG. 11(a)) during one rotation, the recording position of one head is corrected from the subcode starting from the time the PG signal is detected, as in the case described above. 1 ((b) in the same figure) The timer value up to the time of detection ((C) in the same figure) is used as a reference, and the correction for the other head is performed using P.
This can be done based on the timer value ((C) in the same figure) from the midpoint of the count value of the counter that detects the G-time signal interval (one rotation) ((D) in the same figure) to subcode 1 ((C) in the same figure).

〔effect〕

As described above, in the magnetic recording/reproduction method, the present invention executes the pause mode or stop mode before recording a recording signal when the recording mode is input, or when the pause mode or stop mode is input during the recording mode. First, a predetermined frame of a PCM audio signal corresponding to 0 level is recorded.

After the recording is finished, recording of the recording signal is started, or the pause mode or stop mode is set. can be prevented.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the R-DAT of the present invention, Figs. 2 to 5 are its flowcharts, Figs. 6 and 7 are block diagrams of its O level signal recording circuit, and Fig. 8 is its track An explanatory diagram of the pattern, FIG. 9 is its waveform diagram, FIGS. 10 and 11 are its timing charts, and FIG. 12 is its RF multiplied signal waveform diagram. 1... Rotating drum 2... Magnetic tape 3.4... Reel 5... Capstan 6.7.8... Servo circuit 9... Oscillation circuit 10... Generation circuit 11.12 ... Switches 13, 14 ... Amplifier circuit 15 ... Decoder 16 ... Encoder 17 ... Detection circuit 18 ... Generation circuit 19 ... Band pass filter 20 ... Detection circuit 21 ... - Sample hold circuit 22...Differential amplifier circuit 23...Sample hold circuit 24...Comparison circuit 25...Counter 26...Flag circuit 27...Detection circuit 28...Flag circuit 29 ... Equalizer 30.31 ... Detection circuit 32 ... Timing signal generation circuit 33 ... Flag circuit 34 ... Detection circuit 35 ... Counter 36 ... Flag circuit 37 ... Counter 38 ... - Timing signal generation circuit 39... Counter 40... Control circuit 41... Input means 42... Inverter 43... OR gate 51... A/D conversion circuit 52, 53... Memory 54. ...Generation circuit 55, 56, 57...Switch 58...Interleaving circuit 59...Additional circuit 60...Memory 61...Counter 62...Delay type flip-flop 63...R-S More than flip flops

Claims (1)

[Claims] Before recording the recording signal when the recording mode is entered,
Or, when pause mode or stop mode is input during recording mode, before executing the pause mode or stop mode, record a predetermined frame of a PCM audio signal corresponding to 0 level, and after the recording is completed, the recording A magnetic recording and reproducing method characterized by starting recording of a signal or setting the pause mode or stop mode.