JPS63244301A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To remove the possibility of a malfunction due to an unfinished erasure, etc., by monitoring the recording state of a magnetic tape, and switching automatically the mode so as to correspond to the recording state at the time of a recording mode or an post-recording mode. CONSTITUTION:The recording mode or the post-recording mode is inputted by an inputting means 41. A detecting means 34 monitors and detects a tracking signal or a recording signal. When the recording signal or the tracking signal is detected at the time of the recording mode, a control circuit 40 switches automatically the recording mode into the post-recording mode. Or again, when the tracking error signal comes not to be detected at the time of the post- recording mode, the control circuit 40 switches automatically the post-recording mode into the recording mode. Thus, the malfunction, such that the unfinished erasure is generated, is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device typified by R-DAT.

[Summary of the invention]

In the present invention, the recording state of the magnetic tape is monitored during recording mode or after-recording mode, and the mode is automatically switched in accordance with the recording state.

[Conventional technology]

In R-DAT, a magnetic tape is wound approximately 90 degrees around a rotating drum equipped with a pair of rotating heads A and B spaced apart from each other by 180 degrees, and information is recorded and reproduced690.
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, respectively. Further, tracking signals f4 to f4 (ATF signals) are recorded between the subcode signal and the PCM audio signal. F is the pilot signal (130KHz), f
2 is the track traced by rotating head A (track A
) is a synchronization signal (522KHz), f is a synchronization signal (784KHz) of a track (track B) traced by rotary head B with an azimuth different from that of rotary head A, and f4 is an erasure signal (1.5MHz).

The tracking error signal is the synchronization signal f2 or f.

It is generated from the level difference between the pilot signal f□ (crosstalk component) reproduced from the right track at the time of detection and the pilot signal f1 (crosstalk component) reproduced from the left track after a predetermined time has elapsed.

[Problem that the invention seeks to solve]

By the way, there are cases where information once recorded on a magnetic tape is erased and new information is recorded. In this case, the erased bureaucratic information can be recorded using a dedicated erasing head. However, this requires a special erasing head, which increases the cost.

Therefore, new information may be overwritten (overwritten) on old information. At this time, the original recording signal (PC
Since the ATF signal has a relatively high frequency, there is no problem with the ATF signal, but since the ATF signal has a relatively low frequency, residual erasure may occur. Since the pilot signal f has the lowest frequency and is difficult to erase, its recording level is set lower than that of other signals. However, lowering the recording level too much will not only make detection difficult;
Connect the pilot signal f to another signal (e.g. synchronization signal f2)
When overriding the above signal, other signals will not be sufficiently erased and will remain. As a result, when there is no cancellation residual, an envelope as shown in FIG. 13(b) is detected from the pilot signal shown in FIG. 13(a), but due to interference with the cancellation residual component, the pilot signal is ) (in the case of addition) or (e) (in the case of subtraction), and the respective envelopes become as shown in (d) or (f) in the figure. Therefore, under normal conditions, the level of the pilot signal on the on-track and the pilot signal as a crosstalk component from the left and right tracks is as shown in Figure 14 (a), and the S curve of the tracking error signal is as shown in Figure 14 (b).
When one and the other of the crosstalk components are subjected to subtraction or addition interference, respectively, as shown in Figure 15(a), the figure-8 curve has an offset as shown in Figure 15(b). will occur.

[Means for solving problems]

The present invention provides a magnetic recording and reproducing device that includes: an input means for inputting a recording mode or an after-recording mode; a detection means for detecting a tracking signal or a recording signal in a recording mode or an after-recording mode; A control circuit that switches the recording mode to an after-recording mode when a signal or a tracking signal is detected, or switches the after-recording mode to a recording mode when a tracking signal is no longer detected in the after-recording mode. do.

[Effect]

Recording mode or after-recording mode is input by the input means. The detection means monitors and detects the tracking signal or recording signal. When a recording signal or a tracking signal is detected in the recording mode, the control circuit automatically switches the recording mode to the after-recording mode.

Alternatively, when the tracking error signal is no longer detected in the after-recording mode, the control circuit automatically switches the after-recording mode to the recording mode.

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

A clock outputted 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 generation circuit 10 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 reels 3 and 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 rotary heads A and B. Similarly, the ATF signal is sent to the amplifier circuit 14. It is supplied to the rotary heads A and B via a switch 11. The generation circuit 18 is the detection circuit 1
In synchronization with the output of No. 7, a head switching pulse (H8WP) 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, rotating head A.

A reproduced signal output when B traces the 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. The signal that has undergone processing such as 8/10 demodulation, error correction, and error interpolation in the decoder 15 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 f3 component. The 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. When the detection circuit 31 receives a signal having the same period as the synchronization signal f2 (synchronization signal f
2), or when the rotating head B is tracing the magnetic tape, when a signal with the same period as the synchronizing signal f3 is input (when detecting the synchronizing signal f), the edge of the input signal A detection pulse corresponding to the timing signal generation circuit 32 is outputted, and a sample pulse SPI is outputted to the sample hold circuit 21.

When the timing signal generation circuit 32 counts a predetermined number of clocks after the output from the detection circuit 31 is generated (two blocks after the sample pulse SPI is generated).
Generate sample pulse SP2. The flag circuit 33 is set by this sample pulse SP2. When the flag circuit 33 outputs an output to the control circuit 40, it is immediately cleared.

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 and holds the output of the detection circuit 20 at the timing of the sample pulse SPI. The output of the sample hold circuit 21 and the output of the detection circuit 20 are connected to 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 between the outputs of the detection circuit 20 at the timings of the sample pulses SPI 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 B 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 sub-code recording area (when recording a sub-code signal).

In other words, the control circuit 40 outputs a logic O 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 from the control circuit 40 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, in the ATFI region, when the counter value from when the timing signal generation circuit 32 outputs a pulse at a predetermined timing reaches a predetermined value, the counter 3
7 causes the timing signal generating circuit 38 to generate a timing signal indicating the starting point of setting data to be recorded in the PCM recording area, and the encoder 16 . The signal is output to the control circuit 40 or the like. 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 circuit 1 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 is the comparison circuit 24. 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 signal having a high level in the period of the pilot signal having a length of two blocks. The counter 25 counts clocks when a high level signal is input from the comparison circuit 24. The counter 25 outputs an output when a number of clocks corresponding to a period approximately equal to the length of two blocks but slightly shorter than that is counted. 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 supplied to the control circuit 40. Flag circuit 26 is reset immediately after issuing an output to control circuit 40.

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 multiplied signal is detected, the flag circuit 28 is set.

The output is input to the control circuit 40.

The control circuit 4o 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 40
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 Part 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 controlling tracking using the F signal, the tracks in the ATF area and the tracks in other areas will be misaligned by about 45". However, even if the tracks are misaligned in this way, the data cannot be reproduced. It is possible.

While operating in after-recording mode - the output of flag circuit 26 is monitored and when no pilot signal is detected from a predetermined number of consecutive tracks (e.g. 4 tracks), control circuit 40 automatically switches the after-recording mode to record 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 low recording information ends midway through, 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 Bose mode is input from the input means 41, the control circuit 4o controls the encoder 16 to cancel the recording mode and at the same time set the reproduction 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 circuits 7 and 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 0 level of the audio signal is recorded. After this recording operation is completed, the Bose mode is set and the running of the magnetic tape is stopped.

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

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

In the above description, the pilot signal f□ 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 0 level PCM 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. memory 52
．． When data is written to one side of 53, data is read from the other side via 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.

The counter 61 counts the number of rising and falling edges of the head switching pulse, and outputs a pulse to the delay type flip-flop 62 every time the count value changes. Therefore, the flip-flop 62 outputs a signal having the same period as the head switching pulse. This signal switches the switches 55 and 56, so the memory 5
2 and 53 alternately repeat write and read operations.

On the other hand, at the timing of recording the 0 level signal, the control circuit 40 resets the R-S flip-flop 63. Therefore, the O level signal (digital signal) generated by the generating circuit 54 is selected and output by the switch 57 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, the switch 57 is switched to the switch 56 side again.

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 waveform of the reproduced signal at the joint will 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 pause 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 a 0-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.

During one rotation of the rotating drum 1, two P (dfi number (first
0 (a), the reproduction operation detecting circuit 17
The control circuit 40 starts a built-in timer when one of the PG multiplied signals (PGl) is detected ((C) in the figure). The control circuit 40 is connected to the decoder 15
is controlled 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 for the other PG multiplied signal PO2). 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, the present invention provides a magnetic recording and reproducing apparatus that includes: an input means for inputting a recording mode or an after-recording mode; a detection means for detecting a tracking signal or a recording signal during a recording mode or an after-recording mode; The control circuit includes a control circuit that switches the recording mode to an after-recording mode when a recording signal or a tracking signal is detected, or switches the after-recording mode to a recording mode when a tracking signal is no longer detected in the after-recording mode. So,
If a tracking signal has already been recorded, it is used as is, so there is less risk of malfunction due to unerased data.

[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 0 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 chart, Fig. 12 is its RF multiplied signal waveform diagram, Fig. 13 is a waveform diagram in conventional R-DAT, and Fig. 13 is its waveform diagram. FIGS. 14 and 15 are characteristic diagrams thereof. 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 Flip-Flip Fig. 2 Fig. 30 Fig. 4 Fig. 5 Fig. 6 Fig. 80 (a) (b) (c) Fig. 9 Fig. 10 Fig. 11 (d) -11 Figure 14 (a) (b) Figure 15 (a) (b) Figure 12 (b) Wound H] Oral side Figure 13 (o: (b: (C: (d) (e) (f)

Claims (1)

[Claims] an input means for inputting a recording mode or an after-recording mode; a detection means for detecting a tracking signal or a recording signal in the recording mode or the after-recording mode; and a detection means for detecting the recording signal or the tracking signal in the recording mode. and a control circuit that switches the recording mode to the after-recording mode when the tracking signal is detected, or switches the after-recording mode to the recording mode when the tracking signal is no longer detected in the after-recording mode. magnetic recording and reproducing device.