JPH0740328B2 - Recording method of rotary head type magnetic recording / reproducing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a rotary head type magnetic recording / reproducing apparatus for magnetically recording and reproducing a recording signal on a magnetic tape as a diagonal recording track by a plurality of rotating heads, In particular, it relates to the recording method.

<Outline> The present invention records an erasing signal of a constant frequency output from an erasing signal generating circuit at the end of recording of main information such as audio or video information on the magnetic tape for a certain period of time following the main information. However, the output of noise due to the previously recorded old information is prevented.

<Prior Art> Recently, a magnetic recording / reproducing apparatus for converting an analog signal such as an audio signal into a PCM signal and recording / reproducing it on a magnetic tape has been studied and developed.

As the method, a fixed head is used to record and reproduce as multi-track on a magnetic tape with a fixed head, and a rotary head implemented in a VTR or the like is used to sequentially form diagonal recording tracks on the magnetic tape for recording. There are two types of rotary head types, among them, the latter rotary head type is attracting attention for the reason that the recording amount can be increased.

In this rotary head type, as shown in FIG. 4, the magnetic tape 3 is wound around a rotary drum 1 having two rotary heads 2A and 2B and rotating at a rotational speed V _D at a winding angle of 90 °, and xy The two rotary heads 2A, 2A are slidably contacted with respect to a plane and travel at a speed vt based on the rotation of the capstan 4 in pressure contact with the rotary drum 1 and the pinch roller 5. In 2B, recording tracks TA and TB as shown in FIG. 5 are sequentially recorded and formed.

In the figure, + α ° and −α ° indicate the azimuth angles of the rotary heads 2A and 2B.

The circuit of the conventional recording / reproducing apparatus of such a rotary head type has a circuit configuration as shown in FIG. 6, and at the time of recording, the recording / reproducing switching signal inputted to the input terminal 10 is set to "0" level and the switch 9 is operated. Is turned off and the switches 12A and 12B are turned on through the inverter 11, the analog music or image signal input to the input terminal 6 is converted into a predetermined digital signal by the recording signal processing circuit 7, and amplified by the recording amplifier 8. Recording is performed on the magnetic tape 3 traveling at a constant speed by the rotary heads 2A and 2B through the rotary transformers 13A and 13B.

Further, at the time of reproduction, the recording / reproduction switching signal is set to the "1" level to turn on the switch 9 and turn off the switches 12A and 12B through the inverter 11. The recorded signal is reproduced, and the reproduced signal is reproduced by the rotary transformers 13A and 13A.
After being amplified by a head amplifier 16 through a B and head changeover switch 14, a reproduction signal processing circuit 17 converts the signal into an original analog music or image signal.

During the recording and reproduction, the rotational speed and the rotational speed of the drum motor 21 that drives the rotating drum are detected by the FG and PG detection elements 21A and 21B, respectively, and the drum motor servo circuit 19 and the drum motor driver 20 drive the drum motor 21. In addition to controlling the number of revolutions of the drum motor servo circuit, the head changeover switch 14 is switched every half rotation of the rotary drum by the waveform shaping signal 15 of the PG detection element 21B output from the drum motor servo circuit 19. Capstan motor to drive
Capstan motor servo circuit 22 and capstan motor driver 23 by detecting the rotation speed of 24 with FG detection element 24A
Thus, the rotation speed of the capstan motor 24, that is, the running speed (constant speed running) of the magnetic tape is controlled to be constant.

<Problems to be Solved by the Invention> By the way, in such a rotary head type magnetic recording / reproducing apparatus, in order to erase the information already recorded and newly record the information, generally, the old information of the magnetic tape is used. By overwriting the new information at the position, the old information is erased and the new information is recorded at the same time. In such a recording / reproducing apparatus, a magnetic tape can be wrapped around a rotary drum equipped with a rotary head to record the information. In order to execute the reproduction, the magnetic tape is pulled out from the tape cassette and the tape is wound around the rotating drum (loading), or the tape is separated from the rotating drum and accommodated in the tape cassette (unloading). There is.

However, when the magnetic tape is unloaded and loaded by the operation of the tape loading mechanism, the tape position with respect to the rotating drum is displaced each time due to a malfunction of the tape loading mechanism such as play. Therefore, for example, when loading → first overwrite → unloading → loading → second overwrite, as shown in FIG. 7, the recording end position WD _{1 of the first} overwrite WD ₁ Between the recording start position WD ' ₂ of the _second overwrite DW ₂ and the old main information Wd remains between the _two and the remaining old main information during reproduction.
There is a fear that Wd may be reproduced as noise.

<Means for Solving Problems> The present invention has been made in view of the above-mentioned problems of the related art. A magnetic tape is pulled out from the inside of a tape cassette and wound around a rotary drum at a predetermined angle. In the rotary head type magnetic recording / reproducing apparatus for magnetically recording a recording signal as a diagonal recording track by a plurality of rotating heads, an erasing signal generating circuit for outputting an erasing signal of a constant frequency is provided, and the main information recording is completed. At this time, the erasing signal generating circuit is driven for a certain period of time, and the erasing signal output from the erasing signal generating circuit is recorded on the magnetic tape following the main information by the rotary head. After recording for a certain period of time, the magnetic tape is appropriately run in a direction opposite to the running direction at the time of recording to stop and stop the recording operation.

<Operation> Therefore, according to the recording method of the present invention, by setting the recording time of the erasing signal so that the recording length becomes larger than the maximum positional deviation length of the magnetic tape based on the operation error of the loading mechanism, The new main information can be recorded without leaving the old main information, and there is no possibility that the old main information will be reproduced as noise during reproduction.

<Example> Hereinafter, one example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block circuit diagram of a magnetic recording / reproducing apparatus which embodies the tape position signal recording method according to the present invention. For convenience of explanation, the same parts as those in the prior art are designated by the same reference numerals.

Therefore, in the description of the circuit configuration of the present invention, only the characteristic portion of the present invention different from the conventional circuit will be described.

Reference numeral 25 denotes a pulse generation circuit, which has a function of converting the output (analog signal) of the FG detection element 24A indicating the rotation speed of the capstan motor 24 into a pulse signal.

A control circuit 26 is shown in FIG. 2 as a concrete example of the circuit. An input terminal 27 for inputting an overwrite command signal from an overwrite command circuit (not shown) and first to third controls are provided. Output terminals 29 to 31 for outputting signals, an AND circuit 32 for deriving the first to third control signals to these output terminals, an RS flip-flop (hereinafter referred to as FF) 33, an up / down counter 34.
And inverter circuits 35 and 36 and AND circuits 37 and 38. In particular, the up / down counter 34 performs up-counting and down-counting within a number from 0 to N (100), for example.

Reference numeral 39 denotes an erasing signal generating circuit, which generates an erasing signal having a single frequency of 4.7 MHz, for example.

40 is a signal changeover switch provided between the recording signal processing circuit 7, the erasing signal generating circuit 39 and the recording amplifier 8,
When the second control signal is "1", the signal related to the main information from the recording signal processing circuit 7 is supplied to the recording amplifier 8, and when the second control signal is "0", the erasing signal is generated. The erasing signal from the circuit 39 is supplied to the recording amplifier 8.

The present invention is configured as described above, and its operation will be described next.

Now, load the tape cassette containing the magnetic tape on which the main information is already recorded into the deck of the device, pull out the magnetic tape and load it, and then set the recording operation means on the operation panel (not shown). Then, when an operation to overwrite is performed, the overwrite command signal input from the input terminal 27 to the control circuit 26 becomes the "1" level, so that the control circuit 26 sets the FF33 to the output state. Since the second control signal from 30 is set to "1" level and the output from the inverter circuit 35 is set to "0" level, the output of the AND circuit 32, that is, the first control signal from the output terminal 29 is set to "1" level. The output of the up / down counter 34, that is, the output of the output terminal 31 (third control signal) is set to the "1" level.

Therefore, since the second control signal is at the "1" level, the signal changeover switch 40 is turned on to the upper side to supply the signal related to the main information of the recording signal processing circuit 7 to the recording amplifier 8. The first control signal is "0"
Since it is at the level, the switch 9 which directly receives the first control signal (“0”) is turned off, and the switches 12A and 12B which are received via the inverter circuit 11 are turned on.

Therefore, in this state, when the drum drum 21 and the capstan motor 24 are driven, the rotary drum and the capstan rotate, the magnetic tape runs at a constant speed, and an analog music or image signal is input from the input terminal 6, The analog signal is converted into a digital signal by the recording signal processing circuit 7 and amplified by the recording amplifier 8 as a signal related to the main information, and then supplied to the rotary transformers 13A and 13B, and the rotary heads 2A and 2B. It is recorded on the magnetic tape at (see a ₁ portion of the recording pattern of Figure 3).

At this time, the drum motor 21 detects the FG detection elements 21A, PG
The magnetic tape is run at a constant speed according to the operations of the drum motor servo circuit 19 and the drum motor driver 20 based on each detection output of the detection element 21B, and the magnetic tape is run at a constant speed.

In this way, when the new main information is overwritten on the magnetic tape on which the old main information is recorded, and when the overwriting ends, the above-mentioned overwrite command signal is accompanied by this. It will be converted to "0" level.

Then, based on the fact that this overwrite command signal has become "0" level, in the control circuit 26, the output of the inverter circuit 35 becomes "1", so that the FF 33 is reset and the output terminal 30 outputs the second signal. Control signal is “0”
The level is set and the signal changeover switch 40 is turned on downward to connect the erasing signal generating circuit 39 to the recording amplifier 8.

At this time, the output of the inverter circuit 35 is "1".
At the level, one input of the AND circuit 32 becomes the "1" level, but the output of the up / down counter 34 is at the "1" level, and the other input receiving it via the OR circuit 37 and the inverter circuit 36 Since it is at "0" level, its output is kept at "0" level, and the first control signal output from the output terminal 29 continues to be at "0" level, turning off the switch 9 and turning on the switches 12A and 12B. Connect states.

Therefore, after overwriting the main information, the erasing signal output from the erasing signal generating circuit 39 reaches the recording amplifier 8 based on the switching of the overwriting command signal to the "0" level, and this After being amplified by rotary transformer 13
It is supplied to A and 13B and recorded on the magnetic tape by the rotary heads 2A and 2B.

Also, an inverter circuit that has become "1" level based on the above-mentioned overwrite command signal being converted to "0" level.
Since the output of 35 is input to one side of the AND circuit 38, the AND circuit 38 raises / lowers the pulse signal from the pulse generator 25 accompanying the rotation of the capstan motor 24 in combination with the recording of the erasing signal. Supply to the counter 34, and the counter 34
Let the upcounter run.

Then, when the up-counting operation of the counter 34 proceeds and the count value reaches a predetermined value (N), the output of the up-down counter 34, that is, the third control signal becomes "0" level, On the one hand, this is supplied to the inverter circuit 36 via the OR circuit 37, and is inverted here to become a "1" level signal, which is input to one input terminal of the AND circuit 32 to output the output of the AND circuit 32. The first control signal becomes the "1" level because it is set to the "1" level in combination with the output ("1" level) of the inverter circuit 35, and the switch 9 and the switches 12A and 12B are turned on. In short, the rotary heads 2A and 2B are set to the reproduction state.

On the other hand, when the third control signal output from the up / down counter 34 is switched to the "0" level, the capstan motor driver 23 reverses the capstan motor 24, and the magnetic tape is removed. Run in the opposite direction at a constant speed.

Then, at this time, since the output of the AND circuit 32 becomes the "1" level, such a signal sets the up / down counter 34 to the down count state, so that a pulse is generated due to the reverse running of the magnetic tape. The pulse signal from the device 25 passes through the AND circuit 38 and the up / down counter 34
Is supplied to the counter 34 and causes the counter 34 to count down from the predetermined value N.

When the reverse running of the magnetic tape progresses and the count value of the up / down counter 34 reaches 0, the output (third control signal) of the up / down counter 34 is again "1".
When the level is reached, the capstan driver 23 is stopped and the reverse rotation of the capstan motor 24 is stopped to end the recording operation.

As described above, once the magnetic tape on which the new main information A ₁ and the erasing signal B have been recorded (overwritten) is unloaded and then reloaded, the magnetic tape is positioned on the magnetic tape due to a malfunction of the loading mechanism or the like. Although a shift occurs, since the recording length of the erasing signal is made larger than the position shift length of the magnetic tape at the time of loading, if new main information is overwritten on the magnetic tape after the reloading, beginning of the main information by overwriting becomesゝbe positioned on the recording pattern B of the erasing signal as the recording pattern a ₂ of FIG. 2.

Next, the reproduction state will be described. To obtain the reproduction state, it can be obtained by inputting a "1" level reproduction signal to the input terminal 41.

That is, by the reproduction signal "1", the switch 9 is turned on and the switches 12A and 12B are turned off via the OR circuit 28 to disable the recording system, and the FG output of the FG detection element 25A is directly transferred to the capstan. The motor is supplied to the motor servo circuit 22, and the capstan motor driver 23 is used to drive the capstan motor.
Rotate 24 at a constant speed to run the magnetic tape at a constant speed.

Therefore, according to the drive of the drum motor 21 and the capstan motor 24, the rotary head 2 is moved from the magnetic tape running at a constant speed.
The reproduction signal (digital) detected by A and 2B reaches the reproduction amplifier 16 through the head changeover switch 14 which selectively switches in synchronization with the rotation of the rotary drum, and is amplified by the reproduction signal processing circuit 17 after being amplified by this. Demodulated into an analog signal.

Even if the erasing signal (recording pattern B in FIG. 3) is reproduced during this reproduction, the reproducing signal processing circuit 17 does not perform data processing because the erasing signal has a single frequency of 4.7 MHz. Not played as sound.

<Effect> According to the recording method of the present invention as described above, when the magnetic tape is temporarily unloaded after the recording operation and then the magnetic tape is loaded and the recording operation is restarted, that is, the overwrite operation is started, Even if there is a displacement between the information recording end position and the current recording main information recording start position, the old main information can be surely overwritten without leaving the old main information. It is possible to obtain a noise-free reproduced sound without generation of noise due to the remaining.

[Brief description of drawings]

FIG. 1 is a block-like electric circuit diagram showing an embodiment of a rotary head type magnetic recording / reproducing apparatus according to the present invention, FIG. 2 is an electric circuit diagram showing a concrete example of a control circuit in the same apparatus, and FIG. FIG. 4 is a pattern diagram of a recording track in which a tape position signal is recorded by the device, FIG. 4 is a schematic diagram of a rotary head mechanism portion of a general rotary head type magnetic recording / reproducing device,
FIG. 5 is a pattern diagram of a recording track on which a signal is recorded by a rotary head, FIG. 6 is a block electric circuit diagram of a conventional rotary head type magnetic recording / reproducing apparatus, and FIG. 7 is a block diagram of this conventional recording / reproducing apparatus. FIG. 6 is a recording pattern diagram provided for explaining a defect. 2A (2B): rotary head, 7: recording signal processing circuit, 26: control circuit, 39: erasing signal processing circuit.

Claims (1)

[Claims] 1. A rotary head type magnetic recording apparatus wherein a magnetic tape is pulled out from the inside of a tape cassette, wound around a rotary drum at a predetermined angle, and a plurality of rotary heads magnetically record a recording signal as oblique recording tracks on the magnetic tape. The recording / reproducing apparatus is provided with an erasing signal generating circuit for outputting an erasing signal having a constant frequency, and when the main information recording is completed, the erasing signal generating circuit is driven for a certain period of time, and the erasing signal generating circuit outputs the signal. The erasing signal is recorded on the magnetic tape following the main information by the rotary head, and after the erasing signal is recorded for a certain period of time, the magnetic tape is appropriately run in a direction opposite to the running direction at the time of recording. A recording method for a rotary head type magnetic recording / reproducing apparatus, characterized in that control is performed so as to stop the recording operation.