JP3580086B2 - Magnetic recording / reproducing device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus having a simultaneous reproduction function of dividing recording data into a plurality of systems for simultaneous recording and reproducing substantially simultaneously with a recording operation.
[0002]
[Prior art]
In video tape recorders for broadcast stations (hereinafter referred to as VTRs for broadcasting), it is often difficult to re-record, so to prevent recording failures, a simultaneous playback function that plays back and confirms the recorded content almost simultaneously during recording is necessary. In order to realize this simultaneous reproduction function, a recording head and a reproduction head arranged close to each other, and a rotary transformer for recording and reproduction for transmitting signals to them simultaneously operate, so that a weak reproduction is performed. It is necessary to suppress the crosstalk interference from the recording signal mixed into the signal to a sufficiently low level.
[0003]
By the way, in order to perform recording with high image quality, the data rate becomes high, and it becomes impossible to perform recording with one recording head. For this reason, the recording data is divided into two systems and simultaneously recorded by a plurality of recording heads. In this case, since two recording signals are simultaneously mixed into the reproduction signal, crosstalk interference is further increased, and it becomes more difficult to realize the simultaneous reproduction function.
[0004]
Hereinafter, a conventional broadcast VTR in which recording data is divided into two systems and recorded simultaneously by a plurality of recording heads will be described with reference to the drawings.
[0005]
FIG. 4 is a schematic diagram showing a head arrangement on a rotary cylinder of a conventional broadcast VTR. In FIG. 4, the rotary cylinder 71 rotates counterclockwise. The rotary cylinder 71 is provided with recording heads 72a, 72b, 73a, and 73b and reproducing heads 74a, 74b, 75a, and 75b. A magnetic tape runs obliquely around the rotary cylinder 71 over a section of approximately half a circumference (180 degrees) (not shown).
[0006]
FIG. 5 is a diagram showing a positional relationship between a recording track pattern on a tape and a head. In FIG. 5, tracks are formed diagonally on the magnetic tape 82. Tracks 80a, 80b, 80c and 80d are tracks already recorded by the recording heads 72a, 72b, 73a and 73b, respectively. Tracks 81a and 81b are certain tracks currently recorded by the recording heads 72a and 72b, respectively, as shown in the figure. At this time, the reproducing heads 74a and 74b trace and reproduce the tracks 81a and 81b slightly behind the recording heads 72a and 72b, respectively. Thereby, reproduction is performed almost simultaneously with recording, and the recording state can be confirmed. Although not shown, tracks recorded by the recording heads 73a and 73b are similarly reproduced by the reproducing heads 75a and 75b almost simultaneously with recording.
[0007]
FIG. 6 is a signal system diagram of a recording / reproducing unit in a conventional VTR. In FIG. 6, digital data to be recorded is divided into two systems in advance, and input as recording data 68a and recording data 68b. The recording clock 70 is also input.
[0008]
The recording data 68a is latched by the recording clock 70 in the latch circuit 69a, and becomes a recording signal 83a synchronized with the recording clock. Similarly, the recording data 68b is latched by the recording clock 70 in the latch circuit 69b and becomes a recording signal 83b.
[0009]
The recording signal 83a is input to a switch 86a controlled by a recording head switch signal 84a synchronized with the rotary cylinder 71. While the recording head 72a is in contact with the magnetic tape, the switch 86a is connected to the upper side. At this time, the recording signal passed through the switch 86a is amplified by the recording amplifier 88a, guided to the recording head 72a on the rotary cylinder 71 via the recording rotary transformer 89a, and recorded on the magnetic tape. Further, during a period in which the recording head 73a is in contact with the magnetic tape, the switch 86a is connected to the lower side. At this time, the recording signal passed through the switch 86a is guided to the recording head 73a on the rotary cylinder 71 via the recording amplifier 94a and the recording rotary transformer 95a, and the signal is recorded on the magnetic tape.
[0010]
In exactly the same way, the recording signal 83b is input to a switch 86b controlled by a recording head switch signal 84b synchronized with the rotating cylinder 71. While the recording head 72b is in contact with the magnetic tape, the switch 86b is connected to the upper side. At this time, the recording signal passed through the switch 86b is amplified by the recording amplifier 88b, guided to the recording head 72b on the rotary cylinder 71 via the recording rotary transformer 89b, and the signal is recorded on the magnetic tape. During the period when the recording head 73b is in contact with the magnetic tape, the switch 86b is connected to the lower side. At this time, the recording signal passed through the switch 86b is guided to the recording head 73b on the rotary cylinder 71 via the recording amplifier 94b and the recording rotary transformer 95b, and the signal is recorded on the magnetic tape.
[0011]
Next, the operation on the reproduction side will be described. The switch 87a is controlled by a reproducing head switch signal 85a synchronized with the rotary cylinder 71, and is on the upper side during the period when the reproducing head 74a is in contact with the magnetic tape, and is on the lower side when the reproducing head 75a is in contact with the magnetic tape. Connected to each other. Therefore, while the reproducing head 74a is in contact with the magnetic tape, the signal reproduced by the reproducing head 74a on the rotary cylinder 71 is amplified by the reproducing amplifier 93a through the reproducing rotary transformer 92a, and is amplified through the switch 87a. Is input to the conversion circuit 100a. During the period when the reproducing head 75a is in contact with the magnetic tape, the signal reproduced by the reproducing head 75a is amplified by the reproducing amplifier 99a via the reproducing rotary transformer 98a and input to the equalizing circuit 100a via the switch 87a. You. In the equalization circuit 100a, the frequency characteristics of the system from recording to reproduction are corrected and equalized so that the code of the recorded data can be discriminated and becomes an equalized signal 103a. The equalized signal 103a is input to a clock recovery circuit 106a, and a clock signal 107a synchronized with the reproduced data is obtained. Further, the equalization signal 103a is input to the discrimination circuit 104a, discriminates the sign of the data at the timing of the clock 107a, and is output as reproduction data 105a.
[0012]
In exactly the same way, the switch 87b is controlled by a reproducing head switch signal 85b synchronized with the rotating cylinder 71, and is turned upward while the reproducing head 74b is in contact with the magnetic tape, while the reproducing head 75b is in contact with the magnetic tape. During this period, they are connected to the lower side, respectively. Therefore, during the period when the reproducing head 74b is in contact with the magnetic tape, the signal reproduced by the reproducing head 74b on the rotary cylinder 71 is amplified by the reproducing amplifier 93b via the reproducing rotary transformer 92b, and is amplified via the switch 87b. Input to the conversion circuit 100b. During the period when the reproducing head 75b is in contact with the magnetic tape, the signal reproduced by the reproducing head 75b is amplified by the reproducing amplifier 99b via the reproducing rotary transformer 98b and input to the equalizing circuit 100b via the switch 87b. You. In the equalization circuit 100b, the frequency characteristics of the system from recording to reproduction are corrected, and equalization is performed so that the code of the recorded data can be discriminated, and becomes an equalized signal 103b. The equalized signal 103b is input to a clock recovery circuit 106b, and a clock signal 107b synchronized with data is obtained. Further, the equalization signal 103b is input to the determination circuit 104b, determines the code of the data at the timing of the clock 107b, and is output as reproduction data 105b.
[0013]
Here, the signals reproduced from the magnetic tape by the reproducing heads 74a, 74b, 75a to 75b are extremely weak, and are about 70 dB lower than the recording current flowing to the recording heads 72a, 72b, 73a to 73b. Therefore, crosstalk interference occurs in which the recording signal leaks into the reproduction signal. At this time, as shown in FIG. 5, for example, the recording heads 72a and 72b operate at the same time. Therefore, in the reproduced signals from the reproducing heads 74a to 75a, crosstalk interference occurs simultaneously from the two recording signals 83a and 83b. I do. Similarly, with respect to the reproducing heads 74b to 75b, crosstalk interference occurs simultaneously in the reproduced signal from the two systems of recorded signals.
[0014]
FIG. 7 is a waveform diagram for explaining the state of interference when crosstalk interference occurs simultaneously from two recording signals.
[0015]
FIG. 7A shows a crosstalk interference waveform in which the recording signal 83a is mixed into the equalized signal 103a from the recording heads 72a to 73a via the reproducing heads 74a to 75a, superimposed in synchronization with the recording clock 70. It is a waveform diagram. Here, T is one period of the recording clock 70. Similarly, FIG. 7 (b) shows that the recording signal 83b is superimposed on the recording clock 70 in synchronism with the recording clock 70, in which the crosstalk interference waveform mixed from the recording heads 72b to 73b into the equalization signal 103a via the reproducing heads 74a to 75a. FIG. Further, FIG. 7 (c) shows a waveform in a case where the crosstalk from the recording signal 83a and the crosstalk from the recording signal 83b are simultaneously present. The waveform of FIG. 7 (a) and the waveform of FIG. 7 (b) are added. Things.
[0016]
Here, as seen in FIGS. 7A and 7B, the amplitude of the crosstalk disturbance from the recording signal 83a and the recording signal 83b becomes maximum at the same time. For this reason, when there is interference from both at the same time, as shown in FIG. 7 (c), the amplitude of the interference is approximately twice as large as in the case of only one of them.
[0017]
[Problems to be solved by the invention]
As described above, when there are two recording signals, the amplitude of the disturbance becomes approximately twice as large as when only one of them is used. That is, in order to realize simultaneous reproduction, it is necessary to reduce the magnitude of crosstalk disturbance per system to half compared to the case where the recording signal is only one system. Therefore, it is difficult to realize the simultaneous reproduction function. Further, if the number of recording signal systems further increases, simultaneous reproduction becomes more difficult.
[0018]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic recording / reproducing apparatus capable of simultaneously recording a plurality of systems of recording data and having a simultaneous reproduction function while suppressing an increase in amplitude of crosstalk interference.
[0019]
[Means for Solving the Problems]
Magnetic recording and reproducing apparatus of the present invention for this purpose, and two or two pairs of recording head for recording on a magnetic recording medium in synchronization with recording digital data signals of two systems to the recording clock, recorded digital data signals a reproducing head for reproducing simultaneous recording operation and a, in which the two at different each other phase of the recording digital data signals of the system so as to supply to the two or two pairs of recording heads.
[0020]
According to the present invention, it is possible to provide a magnetic recording / reproducing apparatus which suppresses the amplitude of crosstalk disturbance and has a simultaneous reproducing function even when a plurality of systems of recording data are recorded simultaneously.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0022]
(Embodiment 1)
The magnetic recording / reproducing apparatus according to the first embodiment of the present invention divides recording data into two systems and records the data at the same time by a plurality of recording heads, as in the prior art. Also, as shown in FIGS. 4 and 5, a total of four recording heads and a total of four reproducing heads are provided on a small rotating cylinder, and a digital tape is mounted on a magnetic tape that runs obliquely around the rotating cylinder. The point of recording and reproducing the data is the same as in the prior art. The only difference from the conventional example is the part related to the processing of the recording data in the signal system. Therefore, only this part will be described.
[0023]
FIG. 1 is a signal system diagram of a recording / reproducing unit according to the present embodiment. Blocks and signals having the same functions as those of the conventional example shown in FIG. The only difference from the conventional example shown in FIG. 6 is that a delay circuit 64 as a phase shift means is newly provided for one recording data.
[0024]
The recording data 68b is latched by the recording clock 70 in the latch circuit 69b, and becomes a signal 83b synchronized with the recording clock 70. The delay circuit 64 delays the signal 83b by a half period of the recording clock to obtain a recording signal 63b.
[0025]
As a result, the signal of the recording signal 63a (same as the recording signal 83a of FIG. 6) changes in synchronization with the recording clock 70, whereas the recording signal 63b is shifted at a time shifted by a half cycle period of the recording clock. The signal changes.
[0026]
FIG. 2 is a waveform diagram for explaining the state of interference when crosstalk interference occurs simultaneously from two systems of recording signals in the present embodiment.
[0027]
FIG. 2A shows a crosstalk interference waveform in which the recording signal 63a is mixed into the equalized signal 103a from the recording heads 72a to 73a via the reproducing heads 74a to 75a in a manner superimposed in synchronization with the recording clock 70. It is a waveform diagram. Here, T is one period of the recording clock 70. Similarly, FIG. 2B shows the recording signal 63b superimposed on the recording clock 70 in synchronism with the recording clock 70 in which the crosstalk interference waveform mixed into the equalized signal 103a from the recording heads 72b to 73b via the reproducing heads 74a to 75a. FIG. Further, FIG. 2C shows a waveform in a case where the crosstalk from the recording signal 63a and the crosstalk from the recording signal 63b are simultaneously present, and the waveform of FIG. 2A is added to the waveform of FIG. Things.
[0028]
Here, as can be seen in FIGS. 2A and 2B, the crosstalk disturbance from the recording signal 63a and the crosstalk disturbance from the recording signal 63b have the maximum amplitude at the time interval of T / 2. Just off. This is because the change time of the signal of the recording signal 63b is shifted by the delay circuit 64 by the period of T / 2 from the change time of the signal of the recording signal 63a.
[0029]
For this reason, as shown in FIG. 2C, the waveform of the crosstalk interference when there is interference from both at the same time does not have the maximum value of the amplitude being twice as large as that of the one, but is about 1.3 times. It is suppressed.
[0030]
Although FIG. 2 illustrates the crosstalk disturbance waveform mixed from the recording signal 63a and the recording signal 63b into the equalized signal 103a, the crosstalk disturbance waveform from the recording signal 63a and the recording signal 63b to the equalized signal 103b is exactly the same. It is.
[0031]
As described above, in the conventional example, as shown in FIG. 7, the amplitude of the interference is approximately double as compared with the case of only one of the recording signals, whereas in the present embodiment it is approximately 1.0. Only about three times. That is, the allowable value of the crosstalk disturbance for realizing the simultaneous reproduction can be increased as compared with the conventional example, and the simultaneous reproduction function can be easily realized.
[0032]
(Embodiment 2)
Next, a magnetic recording and reproducing apparatus according to a second embodiment of the present invention will be described.
[0033]
This embodiment is different from the first embodiment only in the method of realizing the phase shift means for print data, and therefore only this part will be described.
[0034]
FIG. 3 is a signal system diagram of the recording / reproducing unit according to the present embodiment. Blocks and signals having the same functions as those of the first embodiment shown in FIG. The difference from the first embodiment is that a latch circuit 67 and an inversion circuit 66 are used in place of the delay circuit 64 as a phase shift unit for recording data.
[0035]
The recording data 68b is latched by the recording clock 70 in the latch circuit 69b, and becomes a signal 83b synchronized with the recording clock 70. The signal 83b is input to the latch circuit 67. The inverting circuit 66 inverts the recording clock 70 and inputs the inverted clock 65 as a clock for the latch circuit 67. As a result, a recording signal 63b synchronized with the inverted clock 65 is obtained. It is assumed that the duty ratio of the recording clock 70 is approximately 50%.
[0036]
As a result, the signal of the recording signal 63a changes in synchronization with the recording clock 70, whereas the signal of the recording signal 63b changes at a time shifted by about a half period of the recording clock.
[0037]
As a result, the crosstalk interference waveform from the recording signal has the relationship shown in FIG. 2 exactly as in the first embodiment. In other words, in the conventional example, the amplitude of the disturbance is about twice as large as that of only one of the recording signals, whereas in the present embodiment, it is only about 1.3 times. For this reason, the allowable value of the crosstalk disturbance for realizing the simultaneous reproduction is larger than that of the conventional example, and the simultaneous reproduction function can be relatively easily realized.
[0038]
In the above-described first and second embodiments, a two-channel configuration in which recording data is divided into two systems and recording is performed simultaneously by two heads has been described. However, the present invention is not limited to this. That is, in order to perform recording and reproduction at a higher data rate, when recording and reproducing with N channels (N is 2 or more) by further increasing the number of channels, one or several recording data Can be similarly configured by shifting the phase of each other.
[0039]
Further, in the above-described first and second embodiments, an example has been described in which signals per system are alternately recorded or reproduced by a set of two heads located at 180 ° opposite positions. May be recorded or reproduced by a single head. Further, a configuration may be employed in which signals per system are alternately recorded and reproduced by three or more heads.
[0040]
Further, in the first and second embodiments, the magnetic recording / reproducing apparatus in which the head is mounted on the rotary cylinder has been described, but the present invention is not limited to this. That is, a tape recording device using a fixed head, or a device for recording on a rotating medium such as a hard disk may be used.
[0041]
【The invention's effect】
As described above, according to the present invention, even when recording data of a plurality of systems is recorded at the same time, the phase of the recording data is made different from each other to suppress an increase in the amplitude of crosstalk interference, and the simultaneous reproduction function is provided. A magnetic recording / reproducing device provided with the same.
[Brief description of the drawings]
FIG. 1 is a signal system diagram of a recording / reproducing unit of a magnetic recording / reproducing device according to a first embodiment of the present invention. FIG. 2 is a waveform diagram of crosstalk disturbance of the magnetic recording / reproducing device according to the first and second embodiments of the present invention. FIG. 3 is a signal system diagram of a recording / reproducing unit of a magnetic recording / reproducing apparatus according to Embodiment 2 of the present invention. FIG. 4 is a head on a rotary cylinder in Embodiments 1 and 2 of the present invention and a conventional magnetic recording / reproducing apparatus. FIG. 5 is a schematic view showing an arrangement. FIG. 5 is a schematic view showing a relationship between recording tracks on a magnetic tape and a head arrangement in the first and second embodiments of the present invention and a conventional magnetic recording / reproducing apparatus. Signal system diagram of recording / reproducing unit [FIG. 7] Waveform diagram of crosstalk disturbance of conventional magnetic recording / reproducing apparatus [Description of reference numerals]
64 Delay circuit 66 Inverting circuit 67, 69a, 69b Latch circuit 71 Rotating cylinder 72a, 72b, 73a, 73b Recording head 74a, 74b, 75a, 75b Reproducing head 82 Magnetic tape

Claims (3)

And two or two pairs of recording heads for recording digital data signals of two systems for recording on a magnetic recording medium in synchronization with a recording clock, a reproducing head for reproducing digital data signal recording operation at the same time recorded, the two systems Recording digital data signal
Magnetic recording and reproducing apparatus comprising a phase shifting means made different from each other supplied to the two or two pairs of recording heads phase. Phase shifting means, the magnetic recording and reproducing apparatus according to claim 1, further comprising a delay means for delaying only one one cycle period of 2 minutes of recording digital data signal said recording clock of the recording digital data signals of two systems. Phase shifting means comprises a reversing means for generating an inverted clock signal obtained by inverting the write clock signal, and a latch means for latching the one recording digital data signals among the recorded digital data signals of two systems by the inverted clock signal 3. The magnetic recording / reproducing apparatus according to claim 2, wherein:

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