JPH09204602A - Helical scanning type magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a helical scanning type recording and reproducing device which records an information signal in the state of high reliability by eliminating overwriting at the time of starting the recording of an already recorded magnetic tape without the use of a flying erase head. SOLUTION: The envelope of a reproduced signal is detected by an envelope detection circuit 18, and in the case of an already recorded tape, a magnetic tape corresponding to a physical distance between a fixed erasing head 2 and a magnetic head 4 is detected by a capstan control circuit 21 in conformity with a tape running command outputted from a system controller 22 before recording, and after the erasure of the above-mentioned same distance is performed by the fixed erasing head 2, recording is started. Or, a magnetic tape corresponding to the above-mentioned physical distance is rewound, and after the erasure of the above-mentioned same distance is performed by the fixed erasing head 2, recording is started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scanning type magnetic recording / reproducing apparatus, and more particularly, at the time of recording, prior to recording, a fixed erasing head erases a previous magnetic tape record and then records. The present invention relates to a helical scanning type magnetic recording / reproducing apparatus for recording in a highly reliable state.

[0002]

2. Description of the Related Art There is a video telephone system (or a video conference system) as a means for transmitting video and audio information using a transmission line having a low transfer rate. This is one that uses the current analog signal telephone line due to the development of video information compression technology, and transfers moving images or still images at a transfer rate of about 14.4 kbps to 28.8 kbps. When a digital line network (ISDN or the like) is used, a transfer rate n times 64 kbps can be realized, and higher quality video information can be transmitted.

By the way, in addition to the above-mentioned video telephone system, in a surveillance system for crime prevention and an observation system for a long time phenomenon, monitoring / observation video information, music information and digital information accompanying these are monitored at a remote place. There is a request to be able to record / play back. These requests are transmitted by transmitting video / audio compression information to a remote place using a telephone line or the like by the video and audio compression transmission technology applying the above video telephone system, and transmitting the transmitted information intermittently called a time lapse VTR. This can be realized by recording and reproducing in a compatible recording / reproducing device. A low transfer rate digital information recording / reproducing apparatus using this time-lapse VTR has been proposed in Japanese Patent Application No. 6-138521 "Digital Information Recording / Reproducing Apparatus".

As a recording / reproducing apparatus for recording intermittently recorded data such as the time lapse VTR, which records the digital signals, a helical scanning type magnetic recording / reproducing apparatus for obliquely winding and recording a magnetic tape on a rotating cylinder having a magnetic head attached. Is mentioned.

FIG. 2 is a schematic view showing the mechanism of a helical scanning type magnetic recording / reproducing apparatus. In FIG. 2, the magnetic tape 1 wound on the supply reel 61 is pulled by the pinch roller 65 and the capstan 5 and wound on the take-up reel 62. In the meantime, the fixed erasing head 2,
A rotary cylinder 3 to which a magnetic head 4 for recording / reproducing is attached, and a C for recording / reproducing a CTL signal.
There is a TL head 64 and the like, and the magnetic tape 1 comes into contact with these heads to erase, record, and reproduce signals. Further, there are guide posts 63 for keeping the tape running path correct.

In recording an information signal, first,
The fixed erasing head 2 erases the previous information signal, and then the magnetic head 4 records the information signal.
Here, a certain length L (the portion shown by the thick line in FIG. 2) exists between the fixed-width erasing head 2 and the magnetic head 4 in the rotating cylinder 3. In the case where the magnetic tape is a recorded tape, at the start of recording, the fixed erasing head 2 erases previously recorded information by the length L.
Will not be erased and will be overwritten and recorded. As a matter of course, in the overwritten and recorded portion, the S / N of the reproduction signal deteriorates because the previous recording signal remains to some extent.

In the analog signal, the quality of the reproduced signal deteriorates in proportion to the deterioration of the S / N of the reproduced signal, but in the case of the digital signal, when the S / N of the reproduced signal deteriorates to a certain level or lower, an error correction process is performed. Is no longer possible and the quality of the reproduced signal is significantly reduced. The running time of this length L is a few seconds in terms of time in a conventional so-called general VTR and a magnetic recording device that writes 60 tracks per second, so there is no great influence, but an intermittent write of one track every few seconds. In the case of a magnetic recording device, the time is about tens of minutes, and the influence is large. From the above matters, in order to use the helical scanning type magnetic recording / reproducing apparatus as a recording / reproducing apparatus for intermittent recording, which is referred to as the time lapse VTR for recording the digital signal or the like, the recording of the recorded magnetic tape is performed. The problem of overwriting at the start cannot be understated.

[0008]

As a method for completely eliminating this overwriting, a flying erase head is arranged in front of the recording / reproducing head on the rotary cylinder, and the previous recording signal is erased for each track. There is a way to do it. However, placing the flying erase head increases the production cost. An object of the present invention is to provide a helical scanning type magnetic recording / reproducing apparatus which records a recording signal in a highly reliable state on a magnetic tape without overwriting, without disposing a flying erase head.

[0009]

In order to achieve the above object, as a first means, the present invention is provided with a magnetic head for recording or reproducing an information signal on a magnetic tape, and the above magnetic head. It has a rotary cylinder, a drive means for running the magnetic tape, and a fixed erasing head for erasing the signal recorded on the magnetic tape, and at the time of recording, the magnetic head diagonally tracks on the magnetic tape. To record an information signal, and at the time of reproduction, the magnetic head scans the track to reproduce the information signal. A running distance detecting means for detecting a running distance, a running control means for controlling the driving means for driving the running of the magnetic tape, and the fixed erasing head. The erase signal generating means for providing the erase signal to be provided.

As a second means, the present invention is a magnetic head for recording or reproducing an information signal on a magnetic tape, a rotary cylinder to which the magnetic head is attached, and a driving means for running the magnetic tape. And a fixed erasing head for erasing a signal recorded on the magnetic tape, and at the time of recording, the magnetic head forms an oblique track on the magnetic tape to record an information signal, and at the time of reproduction. In a helical scanning type magnetic recording / reproducing apparatus in which the magnetic head scans a track to reproduce an information signal, a magnetic tape state detecting means for detecting whether the magnetic tape has been recorded or not recorded. When,
A travel distance detecting means for detecting a travel distance of the magnetic tape traveled by the drive means, and a travel control means for controlling the drive means for driving the travel of the magnetic tape;
An erase signal generating means for providing an erase signal to the fixed erase head is provided.

By the first means, the magnetic tape is made to run by the running control means before the information signal is recorded so as not to overwrite the previous recording signal, and at the same time the fixed erasing head and the magnetic head are physically moved. The magnetic tape corresponding to the distance is detected by using the traveling distance detecting means and is erased by the erase signal generated by the erase signal generating means.

Alternatively, in order not to overwrite the previous recording signal, a magnetic tape corresponding to the physical distance between the fixed erasing head and the magnetic head is recorded by using the running distance detecting means before recording the information signal. The same distance is rewound by using the running control means, the running tape is run by the running control means, and the magnetic distance corresponding to the physical distance between the fixed erasing head and the magnetic head is detected. The tape is detected by the running distance detecting means and erased by the erase signal generated by the erase signal generating means.

Further, by the second means, the magnetic tape is reproduced by the magnetic head, the envelope of the reproduced signal is detected, and the level of the envelope is
By comparing with a predetermined reference value, the magnetic tape state detection means by envelope detection or the like for detecting the magnetic tape state, the magnetic tape state detection means before recording the information signal, the magnetic tape to be recorded Determine whether the tape is unrecorded or recorded. If the magnetic tape to be recorded is an unrecorded tape, overwriting will not occur, and recording can be performed as it is.

On the other hand, if the magnetic tape to be recorded has already been recorded, the traveling control means causes the magnetic tape to run and fixed erasure before recording the information signal so as not to overwrite the previous recording signal. The magnetic tape corresponding to the physical distance between the head and the magnetic head is detected by using the running distance detecting means and erased by the erase signal generated by the erase signal generating means, or before recording the information signal, A magnetic tape corresponding to the physical distance between the fixed erasing head and the magnetic head is detected by the traveling distance detecting means, the same distance is rewound by the traveling control means, and then by the traveling control means. While running the magnetic tape, a magnetic tape corresponding to the physical distance between the fixed erasing head and the magnetic head,
It is detected by the traveling distance detecting means and is erased by the erase signal generated by the erase signal generating means.

Furthermore, by the above first and second means,
A part or all of the track is erased by the fixed erasing head, which has no meaning as information at the time of reproduction, and is generated when a new recording is made on the magnetic tape. The length of the portion perpendicular to the longitudinal direction of the track is controlled by the running distance detecting means and the running control means to control the running distance of the magnetic tape, and the erasing signal generating means is used to adjust the erasing amount. By doing so, tracking can be easily performed by making the number of tracks approximately an integral multiple. By the means and actions described above, it is possible to realize a helical scanning type magnetic recording / reproducing apparatus which realizes recording of a recording signal without overwriting without disposing a flying erase head, which is an object of the present invention. Become.

[0016]

Embodiment 1 of the present invention will be described. Here, a magnetic recording / reproducing apparatus called a time-lapse VTR compatible with intermittent recording will be described as an example of the helical scanning type magnetic recording / reproducing apparatus.

FIG. 1 is a block diagram showing the construction of a helical scanning type magnetic recording / reproducing apparatus using the present invention. FIG.
, 1 is a magnetic tape, 2 is a fixed erasing head that erases the entire width of the magnetic tape, 3 is a rotating cylinder, 4 is recording
A magnetic head for reproducing, 5 a capstan for running a magnetic tape, 6 an information signal input terminal, 7 a recording processing circuit for processing the information signal into a signal form suitable for recording, 8 a recording amplifier, 9 fixed. An erase signal generation circuit for giving an erase signal to the erase head 2, 10 a DFG signal generation circuit, 11 a DPG signal generation circuit, 12 a drum motor, 13 a drum control circuit, 14 a switch for switching between recording and reproduction,
Reference numeral 15 is a reproduction amplifier, 16 is a reproduction processing circuit which restores a signal reproduced from a magnetic tape to an original information signal, 17 is an information signal output terminal, 18 is an envelope detection circuit, 19
Is a capstan motor, 20 is a CFG signal generation circuit, 2
Reference numeral 1 is a capstan control circuit, and 22 is a system controller.

First, the flow of a series of information signals will be described. In FIG. 1, in the case of signal recording, the information signal input from the information signal input terminal 6 is supplied to the recording processing circuit 7. The recording processing circuit 7 converts the information signal into a signal form suitable for recording. The converted signal is amplified by the recording amplifier 8 and recorded on the magnetic tape 1 by the magnetic head 4 via the switch 14. On the other hand, at the time of signal reproduction, the signal reproduced from the magnetic tape 1 by the magnetic head 4 is reproduced by the reproduction amplifier 15 via the switch 14.
And is supplied to the reproduction processing circuit 16. The reproduction processing circuit 16 performs a process of restoring the signal from the magnetic head 4 to the original information signal, and outputs it via the information signal output terminal 17.

FIG. 3 shows the capstan control circuit 21 of FIG.
FIG. 3 is a block diagram showing the configuration of FIG. In FIG. 3, 23 is a CFG signal input terminal and 24 is a system controller 22.
Mode signal input terminal, 25 is a CFG signal detection circuit, 26 is a clock generation circuit, 27 is a mode analysis circuit,
28 is a counter, 29 is a CFG signal counter, 30 is a speed detection circuit, 31 is a target CFG count number setting circuit, 3
2 is a target CFG speed setting circuit, 33 is a decoder, 34,
Reference numeral 35 is a comparison circuit, 36 is a drive pulse generation circuit, 37 is a characteristic compensation circuit, 38 is a DA converter (shown as DAC),
39 is a switch, 40 is a motor driver amplifier (MD
41 is an error number output terminal, and 42 is a capstan control signal output terminal.

Of the tape running, the capstan control for intermittent running will be described with reference to FIG. FIG.
CFG output from the capstan motor 19 shown in FIG.
The signal is supplied to the CFG signal detection circuit 25 via the CFG signal input terminal 23. The CFG signal is a frequency signal generated in proportion to the rotation frequency of the capstan motor 19. The capstan motor control circuit 21 runs the tape by one track width at the time of recording and reproducing accompanied by frame feeding.

This is performed in response to the frame advance request signal supplied from the system controller 22 shown in FIG.
This request signal is supplied to the counter 28 and the drive pulse generation circuit 36 via the mode analysis circuit 27. The counter 28 is reset by the request signal from the mode analysis circuit 27. Then, the input CFG signal is counted. The count value of the counter 28 is supplied to the decoder 33, and when the count value reaches a predetermined value, the decode signal is supplied to the drive pulse generation circuit 36. FIG. 4 shows a timing chart of each pulse in the drive pulse generating circuit and the tape traveling speed at that time.

In FIG. 4, (1) is a drive pulse,
(2) is the acceleration pulse and deceleration pulse, and (3) is the tape running speed. The drive pulse generation circuit 36 generates the acceleration pulse shown in (2) of FIG.
In accordance with the decode signal supplied from the decoder 33, the acceleration pulse is stopped and the deceleration pulse of a predetermined time corresponding to the acceleration pulse period is generated. Acceleration pulse and
The deceleration pulse is MD through the B input terminal of the switch 39.
It is supplied to A40, and after power amplification, it is supplied to the capstan motor 19.

Of the tape running, the capstan control when running continuously will be described. The CFG signal detected by the CFG signal detection circuit 25 is supplied to the speed detection circuit 30 and the CFG signal counter 29. Speed detection circuit 3
0 uses the clock generated by the clock generation circuit 26 to obtain the speed from the CFG cycle. Speed detection circuit 3
The speed obtained by 0 is compared with the target speed setting circuit 32 determined by the mode analysis circuit 27 and the comparison circuit 35.
Then, a comparison operation is performed to generate a speed error signal. The generated speed error signal is subjected to characteristic compensation by the characteristic compensation circuit 37 and supplied to the DAC 38. DAC38
Converts the capstan control signal supplied from the characteristic compensation circuit 37 into an analog signal and supplies the analog signal to the MDA 40 via the A input terminal of the switch 39. The MDA 40 amplifies the power of the capstan control signal and supplies it to the capstan motor 19 to rotate the capstan 5 at a predetermined speed.

On the other hand, regardless of whether the tape is running intermittently or continuously, the CFG signal counter 29 counts each time the CFG signal is sensed, and supplies the counted CFG count number to the comparison circuit 34. The target CFG count number setting circuit 31 generates the target count number obtained by the mode analysis circuit 27 and supplies the target count number to the comparison circuit 34. The comparison circuit 34 uses the above-mentioned CFG.
A comparison with the count number is performed, and the error number, which is the difference, is sent to the system controller 22 via the error number output terminal 41.

FIG. 5 is a block diagram showing the configuration of the drum control circuit 13 of FIG. In FIG. 5, 43 is D
FG signal input terminal, 44 is DPG signal input terminal, 45 is a mode signal input terminal from the system controller 22,
46 is a phase reference signal input terminal, 47 is a DFG signal detection circuit, 48 is a DPG signal detection circuit, 49 is a mode analysis circuit, 50 is a switch, 51 is a speed detection circuit, 52 is a phase detection circuit, and 53 is a target speed setting circuit. , 54 is a target phase setting circuit, 55 is a comparison circuit, 56 is a comparison circuit, 57 is an addition & characteristic compensation circuit, 58 is a DA converter (shown as DAC), 59 is a motor driver amplifier (shown as MDA), and 60 is a drum. This is a control signal output terminal.

Next, the drum motor control will be described with reference to FIG. The DFG signal output from the drum motor 12 shown in FIG. 1 is supplied to the DFG signal detection circuit 47. The DFG signal is a frequency signal generated in proportion to the rotation frequency of the drum motor 12. The DFG signal detected by the DFG signal detection circuit 47 is the speed detection circuit 51.
Is supplied to. The speed detection circuit 51 detects the rotation speed of the drum motor 12 by measuring the period of the DFG signal, and supplies the speed detection information to the comparison circuit 55. The speed target setting circuit 53 generates a rotation speed target of the drum motor 12, and supplies the speed target information to the comparison circuit 55. The comparison circuit 55 compares the speed detection information with the above speed detection information, and supplies speed error information, which is the difference, to the addition & characteristic compensation circuit 57.

On the other hand, D output from the drum motor 12
The PG signal is supplied to the DPG signal detection circuit 48. D
The PG signal is a phase signal that synchronizes with the rotation of the drum motor 12 and has a predetermined phase relationship with the rotation phase of the magnetic head 4. The DPG signal detected by the DPG signal detection circuit 48 is supplied to the phase detection circuit 52. Phase detection circuit 5
2 detects the rotation phase of the drum motor 12 by detecting the phase of the DPG signal, and supplies the phase detection information to the comparison circuit. During recording, the target phase setting circuit 54 generates target phase information using the reference signal supplied from the recording processing circuit 7 via the reference signal input terminal 46, and supplies it to the comparison circuit 56. The comparison circuit 56 performs subtraction with the above phase detection information, and supplies the phase error information which is the difference to the addition & characteristic compensation circuit 57.

The addition & characteristic compensation circuit 57 adds the speed error information and the phase error information, performs characteristic compensation filter processing such as phase delay compensation so as to obtain a desired servo characteristic, and supplies it to the DAC 58. It DAC58
Converts the drum control signal supplied from the addition & characteristic compensation circuit 57 into an analog signal and supplies the analog signal to the MDA 59.
The MDA 59 amplifies the power of the drum control signal and supplies it to the drum motor 12 to rotate the rotary cylinder 3 at a predetermined speed in a predetermined phase. The phase reference signal during reproduction is supplied from the mode analysis circuit 49 to the target phase setting circuit 54 via the switch 50.

The system controller 22 issues commands according to modes such as intermittent recording, reproduction and continuous tape running. The capstan control, the drum control, and the erase signal generation circuit read the command output from the system controller and control the command output.

The above is the description of the operation of each block for implementing the present invention. Next, the recording operation, which is the central part of the present invention, will be described in detail. The operation mode during recording is assumed to be intermittent recording.

FIG. 6 shows a flow chart of a series of operation procedures relating to the first embodiment. FIG. 7 shows a summary of the operation of each control device for each mode described in FIG. Further, regarding the first embodiment, a timing chart of each signal in a series of operations is shown in FIG. 8, (1) shows the tape running speed with respect to time, (2) shows the output timing of the erase signal in the fixed erase head, and (3) shows the output timing of the reproduction signal and the recording signal in the magnetic head. .
The detailed operation during recording will be described with reference to FIGS. 6, 7, and 8 described above. When I started recording, first of all,
The drum motor 12 and the drum control circuit 13 rotate the rotary cylinder 3 at a high speed at a constant speed, and the magnetic head 4 reads the recording signal of the magnetic tape 1. The read recording signal is amplified by the reproduction amplifier 15 and sent to the reproduction processing circuit 16 and the envelope detection circuit 18. The envelope detection circuit 18 detects the envelope of the sent recording signal and compares the envelope signal level with a predetermined reference value. As a result of the comparison, when the envelope signal level is equal to or higher than the reference value, the magnetic tape is determined to be a recorded tape, and when the envelope signal level is lower than the reference value, the magnetic tape is determined to be an unrecorded tape.

When it is judged that the magnetic tape to be recorded is an unrecorded tape, the recording state of the information signal is entered,
Intermittent recording of information signals becomes possible. When it is determined that the magnetic tape to be recorded is a recorded tape, the following operation is performed before recording the information signal.

First, the capstan control circuit 21 receives a forward 1x speed traveling command from the system controller 22. The 1x speed is the running speed of the magnetic tape during reproduction or recording of a so-called general VTR. The tape running speed is not particularly limited here as long as the tape position control by counting the CFG signal described below is possible. The capstan control circuit 21 containing the running command rotates the capstan 5 so as to advance the magnetic tape 1 in the forward direction. Also, the system controller 2
An erase command is input to the erase signal generation circuit 9 from 2.

The erasing signal generating circuit 9 outputs a erasing signal to the fixed erasing head 2 to erase the recording signal of the magnetic tape 1. At the same time, by the CFG signal counter 29,
Count the CFG signals. The magnetic tape 1 is run until the detected count value becomes equal to the CFG signal count number corresponding to the predetermined physical distance between the fixed erasing head and the magnetic head. A stop command is issued from the system controller 22 so that the detected count numbers become equal, and the capstan control circuit 21 stops the rotation of the capstan 5.

FIG. 9 is a diagram showing the positional relationship between the magnetic tape and the magnetic head, fixed erasing head, capstan, etc. in the first embodiment and the state of the magnetic tape during recording of the recording state of the tape. In FIG. 9, (1)-
(3) shows the positional relationship between the magnetic tape and the magnetic head, the fixed erasing head, the capstan, and the like in each operation, and the recording state of the tape. Further, the tape area A is a portion of the previously recorded information signal which is desired to be recorded,
In this recording, information signal recording is performed after this part. The tape area B is a portion of the previously recorded information signal that is erased and newly recorded. The tape area C is a portion where the fixed erasing head 2 erases. The tape area D is a portion where an information signal is newly recorded this time. The tape area C ′ is a non-recorded portion of a triangle formed by newly recording an information signal in the tape area C.

The positional relationship between the magnetic tape shown in (1) of FIG. 9 and the magnetic head, fixed erasing head, capstan, etc., and erasing from the magnetic tape in the recording state of the tape by the fixed erasing head, and then stopped The positional relationship between the magnetic tape and the magnetic head, fixed erasing head, capstan, etc. at the stage and the recording state of the tape are as shown in (2) of FIG.

In the state of (2) in FIG. 9, the state of the magnetic tape 1 scanned by the magnetic head 4 is erased from the previous record by the fixed erasing head, so that the magnetic tape 1 is not overwritten. In this state, the information signal recordable state is entered, and the intermittent recording can be started from the recording start track position shown in (2) of FIG. As a result, the positional relationship between the magnetic tape and the magnetic head, fixed erasing head, capstan, etc., and the recording state of the tape are as shown in (3) of FIG.

In (3) of FIG. 9, part or all of the track is erased by the fixed erasing head, and when newly recorded on the magnetic tape, a portion between the previously recorded portion and the newly recorded portion, Although B and C'parts are formed, this part has no meaning as information at the time of reproduction and is an unnecessary part. The recording in the first embodiment is intermittent recording, but it is obvious that normal 1 × speed recording may be performed. When the magnetic tape has been recorded, the tape may be made to run by the running control means and the magnetic tape state detection means, and the CTL signal count and the presence or absence of the CTL signal may be checked. As described above, in the case of a recorded magnetic tape, the recorded signal is erased by the fixed erasing head before recording, and then recording is started, so that the recording signal is recorded in a highly reliable state without overwriting. can do.

Next, the second embodiment will be described. A block diagram showing the hardware configuration, names and the like are the same as those in FIG. 1 used in the first embodiment. The flow of a series of information signals, capstan control, and drum control are also the same as in the first embodiment. The operation of recording an information signal different from that of the first embodiment will be described below. The operation mode during recording is assumed to be intermittent recording. FIG. 10 shows a flowchart of the procedure of a series of operations for the second embodiment. FIG. 7 shows a summary of the operation of each control device for each mode described in FIG.
Further, FIG. 11 shows a timing chart of each signal in a series of operations. In FIG. 11, (1) is the tape running speed with respect to time, (2) is the fixed erasing head,
The erase signal output timing, (3) shows the reproduction signal and the recording signal output timing in the magnetic head. The detailed operation at the time of recording will be described with reference to FIGS. 7, 10, and 11 described above. The difference between the second embodiment and the first embodiment is that before the operation of running and erasing the magnetic tape among the series of operations performed in the case of the recorded magnetic tape of the first embodiment. In addition, the following rewinding operation is added.

A running command of 1 × speed in the rewinding direction enters into the capstan control circuit 21 from the system controller 22. The 1x speed is the running speed of the magnetic tape during reproduction or recording of a so-called general VTR. The tape running speed is not particularly limited here if the CFG signal described below can control the tape position by counting. The capstan control circuit 21 containing the running command,
The capstan is rotated so as to advance the magnetic tape 1 in the rewinding direction.

Incidentally, the system controller 22 does not issue an erasing command and does not erase the magnetic tape. At the same time, the CFG signal counter 29 causes C
Count the FG signals. The magnetic tape 1 is run until the detected count value becomes equal to the CFG signal count number corresponding to a predetermined physical distance between the fixed erasing head 2 and the magnetic head 4. A stop command is issued from the system controller 22 so that the detected count numbers become equal, and the capstan control circuit 21
The rotation of the capstan 5 is stopped.

FIG. 12 is a diagram showing the positional relationship between the magnetic tape and the magnetic head, fixed erasing head, capstan, etc. in the second embodiment, and the state of the magnetic tape during recording of the recording state of the tape. In FIG. 12, (1)
(4) is a magnetic tape and a magnetic head in each operation,
The positional relationship with the fixed erasing head, capstan, etc., and the recording state of the tape are shown. Further, the tape area A is a portion of the previously recorded information signal which is desired to be recorded. In this recording, the information signal recording is performed after this portion. The tape area B is one of the previously recorded information signals.
This is a part to be erased and newly recorded. The tape area C is
This is the part that has been erased by the fixed erasing head 2. The tape area D is a portion where an information signal is newly recorded this time. The tape area C ′ is a non-recorded portion of a triangle formed by newly recording an information signal in the tape area C.

The positional relationship between the magnetic tape shown in (1) of FIG. 12 and the magnetic head, fixed erasing head, capstan, etc. and the magnetic tape in the recording state of the tape are controlled by the capstan control circuit and the capstan. The positional relationship between the magnetic tape and the magnetic head, the fixed erasing head, the capstan, and the like when the magnetic tape is rewound and the recording state of the tape are as shown in (2) of FIG.

After the above rewinding operation, the same operation as in the first embodiment is performed. The positional relationship between the magnetic tape and the magnetic head, the fixed erasing head, the capstan, etc., when erased by the fixed erasing head, and the recording state of the tape are as shown in (3) of FIG. In the state of (3) in FIG. 12, the state of the magnetic tape 1 scanned by the magnetic head 4 is not overwritten because the fixed erasing head 2 has erased the previous record. The recording state of the information signal is entered, and the intermittent recording can be started from the recording start track position shown in (3) of FIG. As a result, the positional relationship between the magnetic tape and the magnetic head, fixed erasing head, capstan, etc., and the recording state of the tape are as shown in (4) of FIG.

In (4) of FIG. 12, part or all of the track is erased by the fixed erasing head, and when newly recorded on the magnetic tape, a portion between the previously recorded portion and the newly recorded portion, That is, B and C'parts are formed, but this part has no meaning as information during reproduction and is an unnecessary part. If the length of this portion is an integral multiple of one track during playback, tracking becomes easy.

This is, for example, the CFG per track.
If the signal count number is 36, the target rewind CFG signal count number or the target erase CFG count number is 3
If set to every multiple of 6 and rewound or erased in accordance with this target value, the length of the unnecessary portion at the time of reproduction becomes an integral multiple of one track, and the track width of the unnecessary portion at the time of reproduction becomes the track width. Since there is no disturbance, tracking during playback becomes easy. As one specific example, the number of CFG signal counts per track is set to 36 because the capstan rotation frequency at normal reproduction 1 × speed is 3 Hz, CF is
G rate 720, 6 recording tracks per second
Assuming 0 tracks / second, 720 × 3 = 216 per second
This is because there are 0 CFG signal counts and the CFG signal count per track is 2160 ÷ 60 = 36.

As in the case of the first embodiment, the recording in the second embodiment is intermittent recording, but it may be normal forward 1 × speed recording, or the CFG rate or the like. It is obvious that is not limited to the above values. Also,
When the magnetic tape has been recorded, the tape may be made to run by the running control means and the magnetic tape state detection means, and the CTL signal count and the presence or absence of the CTL signal may be checked.

As described above, in the case of the recorded magnetic tape, the recorded signal is erased by the fixed erasing head before the recording, and then the recording is started, so that the recording is performed in a highly reliable state without overwriting. The signal can be recorded. Further, in the case of the second embodiment, it is necessary to rewind a specific amount as compared with the first embodiment. However, by performing the rewinding operation before erasing the magnetic tape, the magnetic tape is wasted. 12, that is, in FIG. 12, the B portion is reduced among the B and C ′ portions, and there is an advantage that the magnetic tape can be used more effectively.

[0049]

As described above, according to the present invention, it is possible to record an information signal on a magnetic tape in a highly reliable state without overwriting without disposing a flying erase head which is expensive to produce. .

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a specific example of a helical scanning magnetic recording / reproducing apparatus according to a first embodiment and a second embodiment.

FIG. 2 is a diagram simply showing a mechanism of a helical scanning type magnetic recording / reproducing apparatus.

FIG. 3 is a block diagram showing a configuration of a capstan control circuit.

FIG. 4 is a diagram showing each pulse in a drive pulse generation circuit and a magnetic tape running speed at that time.

FIG. 5 is a block diagram showing a configuration of a drum control circuit.

FIG. 6 is a flowchart summarizing the procedure of a series of operations in the first embodiment.

FIG. 7 is a chart showing an operation list of each control device for each mode.

FIG. 8 is a timing chart summarizing the timing of each signal in a series of operations in the first embodiment.

FIG. 9 is a diagram showing a positional relationship between a magnetic tape and a magnetic head, a fixed erasing head, a capstan and the like in the first embodiment, and a state of the magnetic tape at the time of recording the recording state of the tape.

FIG. 10 is a flowchart summarizing the procedure of a series of operations in the second embodiment.

FIG. 11 is a timing chart summarizing the timing of each signal in a series of operations in the second embodiment.

FIG. 12 is a diagram showing a positional relationship between a magnetic tape and a magnetic head, a fixed erasing head, a capstan and the like in the second embodiment, and a state of the magnetic tape at the time of recording the recording state of the tape.

[Explanation of symbols]

 1 magnetic tape 2 fixed erasing head 3 rotating cylinder 4 magnetic head 5 capstan 6 information signal input terminal 7 recording processing circuit 8 recording amplifier 9 erasing signal generating circuit 10 DFG signal generating circuit 11 DPG signal generating circuit 12 drum motor 13 drum control circuit 14 switch 15 reproduction amplifier 16 reproduction processing circuit 17 information signal output terminal 18 envelope detection circuit 19 capstan motor 20 CFG signal generation circuit 21 capstan control circuit 22 system controller 23 CFG signal input terminal 24 mode signal input terminal 25 CFG signal detection circuit 26 Clock Generation Circuit 27 Mode Analysis Circuit 28 Counter 29 CFG Signal Counter 30 Speed Detection Circuit 31 Target CFG Count Number Setting Circuit 32 Target CFG Speed Setting Circuit 33 Decoder 34 Comparison Circuit 35 Comparison Circuit 36 Drive Pulse Generation Circuit 37 Characteristic Compensation Circuit 38 DAC 39 Switch 40 MDA 41 Error Count Output Terminal 42 Capstan Control Signal Output Terminal 43 DFG Signal Input Terminal 44 DPG Signal Input Terminal 45 Mode Signal Input Terminal 46 Phase Reference Signal Input Terminal 47 DFG signal detection circuit 48 DPG signal detection circuit 49 Mode analysis circuit 50 Switch 51 Speed detection circuit 52 Phase detection circuit 53 Target speed setting circuit 54 Target phase setting circuit 55 Comparison circuit 56 Comparison circuit 57 Addition & characteristic compensation circuit 58 DAC 59 MDA 60 Drum control signal output terminal 61 Supply reel 62 Take-up reel 63 Guide post 64 CTL signal recording / reproducing head 65 Pinch roller

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[Procedure amendment]

[Submission date] January 31, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment will be described. Here, a magnetic recording / reproducing apparatus called a time-lapse VTR compatible with intermittent recording will be described as an example of the helical scanning type magnetic recording / reproducing apparatus.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Okada 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Multimedia system development headquarters

Claims (6)

[Claims] 1. A magnetic head for recording or reproducing an information signal on a magnetic tape, a rotary cylinder to which the magnetic head is attached, driving means for moving the magnetic tape, and a signal recorded on the magnetic tape. Has a fixed erasing head for erasing data, and at the time of recording, the magnetic head forms a track obliquely on the magnetic tape to record an information signal, and at the time of reproduction, the magnetic head scans the track. In a helical scanning type magnetic recording / reproducing apparatus for reproducing an information signal, a running distance detecting means for detecting a running distance of the magnetic tape run by the driving means and a driving means for driving the running of the magnetic tape are controlled. Traveling control means,
Erasing signal generating means for giving an erasing signal to the fixed erasing head is provided, and the magnetic tape is run by the running control means before recording of the information signal, and a physical distance between the fixed erasing head and the magnetic head. The magnetic tape equivalent to is detected using the above-mentioned running distance detection means,
A helical scanning type magnetic recording / reproducing apparatus, wherein erasing is performed by an erasing signal generated by the erasing signal generating means. 2. A magnetic head for recording or reproducing an information signal on a magnetic tape, a rotary cylinder to which the magnetic head is attached, driving means for moving the magnetic tape, and a signal recorded on the magnetic tape. Has a fixed erasing head for erasing data, and at the time of recording, the magnetic head forms a track obliquely on the magnetic tape to record an information signal, and at the time of reproduction, the magnetic head scans the track. In a helical scanning type magnetic recording / reproducing apparatus for reproducing an information signal, a running distance detecting means for detecting a running distance of the magnetic tape run by the driving means and a driving means for driving the running of the magnetic tape are controlled. Traveling control means,
Equipped with an erasing signal generating means for giving an erasing signal to the fixed erasing head, prior to the recording of the information signal, a magnetic tape corresponding to the physical distance between the fixed erasing head and the magnetic head is detected using the running distance detecting means The same distance is rewound by using the running control means, the running tape is run by the running control means, and the magnetic distance corresponding to the physical distance between the fixed erasing head and the magnetic head is detected. A helical scanning type magnetic recording / reproducing apparatus characterized in that a tape is detected by the traveling distance detecting means and erased by an erase signal generated by the erase signal generating means. 3. A magnetic head for recording or reproducing an information signal on a magnetic tape, a rotary cylinder to which the magnetic head is attached, driving means for moving the magnetic tape, and a signal recorded on the magnetic tape. Has a fixed erasing head for erasing data, and at the time of recording, the magnetic head forms a track obliquely on the magnetic tape to record an information signal, and at the time of reproduction, the magnetic head scans the track. In a helical scanning type magnetic recording / reproducing apparatus for reproducing an information signal, a running distance detecting means for detecting a running distance of the magnetic tape run by the driving means and a driving means for driving the running of the magnetic tape are controlled. Traveling control means,
An erasing signal generating means for giving an erasing signal to the fixed erasing head and a magnetic tape state detecting means for detecting whether the magnetic tape is recorded or unrecorded are provided. In the first mode for recording, and before recording the information signal on the recorded tape, the running control means causes the magnetic tape to run, and the fixed erasing head and the magnetic head physically operate. A second mode in which a magnetic tape corresponding to a distance is detected by the running distance detecting means and is erased by an erasing signal generated by the erasing signal generating means. Prior to recording the signal, based on the detection result of the magnetic tape state detecting means,
A helical scanning type magnetic recording / reproducing apparatus characterized by switching between a first mode and a second mode. 4. A magnetic head for recording or reproducing an information signal on a magnetic tape, a rotary cylinder to which the magnetic head is attached, driving means for moving the magnetic tape, and a signal recorded on the magnetic tape. Has a fixed erasing head for erasing data, and at the time of recording, the magnetic head forms a track obliquely on the magnetic tape to record an information signal, and at the time of reproduction, the magnetic head scans the track. In a helical scanning type magnetic recording / reproducing apparatus for reproducing an information signal, a running distance detecting means for detecting a running distance of the magnetic tape run by the driving means and a driving means for driving the running of the magnetic tape are controlled. Traveling control means,
An erasing signal generating means for giving an erasing signal to the fixed erasing head and a magnetic tape state detecting means for detecting whether the magnetic tape is recorded or unrecorded are provided. In the first mode for performing recording, and before recording an information signal on a recorded tape, a magnetic tape corresponding to the physical distance between the fixed erasing head and the magnetic head is used by the running distance detecting means. And rewinding the same distance by using the running control means, and then running the magnetic tape by the running control means and corresponding to the physical distance between the fixed erasing head and the magnetic head. The magnetic tape has a second mode in which it is detected by the traveling distance detecting means and is erased by an erase signal generated by the erase signal generating means. A helical scanning type magnetic recording / reproducing apparatus, which switches between a first mode and a second mode based on a detection result of a state detecting means. 5. The magnetic tape state detecting means according to claim 3 or 4, wherein the magnetic tape is reproduced by the magnetic head, the envelope of the reproduced signal is detected, and the level of the envelope is a predetermined standard. A helical scanning type magnetic recording / reproducing apparatus characterized by using a magnetic tape state detecting means by envelope detection for detecting a magnetic tape state by comparing with a value. 6. A magnetic head for recording or reproducing an information signal on a magnetic tape, a rotary cylinder to which the magnetic head is attached, drive means for running the magnetic tape, and a signal recorded on the magnetic tape. Has a fixed erasing head for erasing data, and at the time of recording, the magnetic head forms a track obliquely on the magnetic tape to record an information signal, and at the time of reproduction, the magnetic head scans the track. A helical scanning type magnetic recording / reproducing apparatus for reproducing an information signal, comprising: a traveling distance detecting means for the magnetic tape, a traveling control means for the magnetic tape, and an erasing signal generating means for giving to the fixed erasing head. For the magnetic tape from which part or all of the track was erased by the head, the previously recorded area that would occur when newly recorded The length of the portion between the lay recorded portion, substantially helical scan type magnetic recording reproducing apparatus of the be adjusted to be an integer multiple claim 1 or 2, wherein the one track.