JP3669310B2 - Magnetic recording / reproducing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a helical recording system in which an information signal is recorded on a magnetic tape by a recording-only rotating head mounted on a rotating drum. The present invention relates to a scan type magnetic recording / reproducing apparatus.
[0002]
[Prior art]
For example, in a helical scan type magnetic recording / reproducing apparatus (VTR) standardized as D-9, the image signal is compressed by digital processing and recorded on a magnetic tape, and this process takes time in units of frames. The decompression process during reproduction also takes the same time. For this reason, when trying to perform image editing, the image on the monitor and the content reproduced on the magnetic tape are shifted, and the accuracy is deteriorated. In order to solve this problem, a head mechanism having a structure in which a recording head and a recording-only head are prepared as a rotating head, and the recording-only rotating head traces a recording track several frames ahead of the recording-only rotating head. (For example, Japanese Patent Laid-Open No. 11-134742: title of invention “tracking control device”).
[0003]
FIG. 4 is a block diagram showing an example of this conventional magnetic recording / reproducing apparatus. In the drawing, first and second rotary heads 2R and 2L constituting a pair head are mounted on the rotating surface of a rotary drum 1 that rotates at a predetermined speed in the counterclockwise direction, with different azimuth angles. In addition, the azimuth angles are different from each other at positions that follow the rotation direction by a predetermined angle (less than 180 degrees) with respect to the rotation direction with respect to the rotation heads 2R and 2L, and are arranged close to each other to form a pair head. Third and fourth rotary heads 3L and 3R are mounted. Further, on the rotating surface of the rotating drum 1, rotating heads 4R and 4L are attached at positions facing the rotating heads 2R and 2L by 180 degrees, and rotating heads 5L are positioned at positions facing the rotating heads 3L and 3R by 180 degrees. And 5R are attached.
[0004]
The rotary heads 2R, 2L, 4R, and 4L are read-only rotary heads, the rotary heads 2R and 4R have the same azimuth angle, and the rotary heads 2L and 4L have the same azimuth angle. The rotary heads 3R, 3L, 5R, and 5L are recording dedicated rotary heads, the rotary heads 3R, 5R, 2R, and 4R have the same azimuth angle, and the rotary heads 3L, 5L, 2L, and 4L are the same azimuth, respectively. Is an angle.
[0005]
The magnetic tape 6 travels in the direction of the arrow 7 while being wound obliquely on the outer peripheral side surface of the rotating drum 1 over a predetermined angle (approximately 180 degrees). The magnetic tape 6 is held between a capstan 8 and a pinch roller (not shown), which will be described later, and travels in the direction of the arrow 7 as the capstan 8 rotates. In FIG. 4, the recording signal processing system is not shown. Further, a signal processing system similar to that in FIG. 4 is provided on the output side of the rotary heads 4R, 4L, and 5R, but the illustration thereof is also omitted. This is to avoid complication of the figure.
[0006]
The recording tracks on the recorded magnetic tape 6 are simultaneously scanned one by one by the rotary heads 2L and 2R constituting so-called pair heads, which are arranged close to each other, and the reproduction signals obtained from the pair of recording tracks are , Separately supplied to preamplifiers 9L and 9R, pre-amplified here, then supplied separately to equalization / quantization circuits 10L and 10R to be converted into digital signals, and further to SYNC / ID extraction circuits 11L and 11R. The synchronization signal (Sync) and address information (ID) in the digital signal are extracted separately.
[0007]
The synchronization signal (Sync) and address information (ID) will be briefly described. In each recording track on the magnetic tape 6, a plurality of data blocks called sync blocks (for example, 356) are synthesized and recorded in time series. Also, on one recording track composed of 356 sync blocks, main information signals relating to image signals and the like are recorded in the form of digital signals, for example, 306 sync blocks, along with subcodes, amble information and other redundant information.
[0008]
Further, each sync block is composed of 112 bytes, a synchronization signal (Sync) is arranged in the first 2 bytes, address information (ID) is arranged in the subsequent 3 bytes, data is arranged in the subsequent 99 bytes, and the remaining This is a format in which parity is arranged in 8 bytes. The synchronization signal (Sync) and address information (ID) in the sync block are the synchronization signal (Sync) and address information (ID) extracted by the SYNC / ID extraction circuits 11L and 11R.
[0009]
The time difference measurement circuit 12 receives the synchronization signal (Sync) and address information (ID) extracted by the SYNC / ID extraction circuits 11L and 11R as inputs, and calculates the time difference between the two synchronization signals or between the two address information. measure. This time difference is zero when the rotary heads 2L and 2R are scanning the recording track with a tracking error of zero. If the rotary heads 2L and 2R are scanning with a tracking error being zero, the time difference is positive or negative depending on the tracking deviation direction. And a value corresponding to the tracking deviation amount.
[0010]
In addition, the time difference measuring circuit 12 is provided with a correction memory 13 for correcting a time difference due to an attachment error of the rotary heads 2L and 2R with respect to the rotary drum 1 as necessary. When the correction memory 13 is provided, the time difference measurement circuit 12 adds the time difference stored in the correction memory 13 to the measured time difference between two synchronization signals or two address information in the reproduction signal. To calculate the true time difference. The time difference measured and calculated by the time difference measurement circuit 12 is accumulated by, for example, n head scans in the time difference memory 14, averaged by the time difference averaging circuit 15, and then input to the terminal a of the switch circuit 16. The
[0011]
The switch circuit 16 is initially connected to the terminal a based on a control signal from the central processing unit (CPU) 17, and supplies the average time difference from the time difference averaging circuit 15 to the capstan servo circuit 20, and its average A servo that controls the rotation of the capstan 8 is applied so that the difference between the time difference and a preset value near zero is minimized, the running control of the magnetic tape 6 is performed, and the tracking control of the rotary heads 2L and 2R is performed. . Thereafter, when the average time difference reaches a predetermined value near zero, the CPU 17 switches the switch circuit 16 to the terminal b side, and performs capstan servo based on the signal from the hill climbing circuit 19.
[0012]
That is, the RF signal reproduced from the magnetic tape 6 by the rotary head 3L is preamplified by the preamplifier 18 and then supplied to the hill-climbing circuit 19 to detect its signal level (RF level). A corresponding control signal is supplied to the capstan servo circuit 20 through the switch circuit 16. The capstan servo circuit 20 controls the rotation of the capstan 8 so that the RF level detected by the hill climbing circuit 19 is maximized.
[0013]
Here, the level (RF level) of the RF signal reproduced from the magnetic tape 6 by the rotary head 3L corresponds to the track shift amount between the rotary head 3L and the recording track, and the track shift between the rotary heads 2L and 2R and the recording track. The relationship is shown in FIG. That is, the above RF level shows the maximum value when the rotary heads 2L, 2R, 3L, and 3R are scanning the center position of the recording track (when the tracking error is zero), and the center position of the recording track. If it deviates from, it will fall rapidly according to the deviation | shift amount.
[0014]
Therefore, the capstan 8 that maximizes the reproduction RF level of the rotary head 3L by the feedback loop including the rotary head 3L, the preamplifier 18, the hill climbing circuit 19, the switch circuit 16, the capstan servo circuit 20, and the capstan 8. By performing this rotation control, it is possible to perform tracking control such that the rotary heads 2L, 2R, 3R, and 3L scan the center position of the recording track.
[0015]
Since the preamplifier 18 only needs to be able to determine the output level, it is not necessary to use an expensive element in which the frequency characteristics and the signal-to-noise ratio are managed. In addition, in this conventional head mechanism, the recording-only rotating head and the reproducing-only rotating head are separated, so that the reproducing head width can be made wider than the recording track width, and the reproduction output fluctuates even if the track is bent. It is possible to obtain a good reproduction condition without any.
[0016]
[Problems to be solved by the invention]
However, in the above-described conventional magnetic recording / reproducing apparatus, as is well known, a rotary transformer 22 is provided between the read-only rotary head 2L and the preamplifier 9L as shown in FIG. The obtained reproduction signal is transmitted to the fixed preamplifier 9L via the rotary transformer 22 (the same applies between the other rotary heads and the preamplifier), but the wiring with the rotary transformer 22 is long and it is easy to pick up noise. There's a problem.
[0017]
In addition, since the recording-only rotating heads 3L, 3R, 5L and 5R and the reproducing-only rotating heads 2L, 2R, 4L and 4R are provided, it is possible to reproduce while recording. It is inevitable that the recording signal that flows through the rotary heads 3L, 3R, 5L, and 5R jumps into the input of the reproduction preamplifiers 9L, 9R, etc., which leads to a decrease in the S / N of the reproduction signal. In the worst case, error correction is performed. It becomes impossible, and reproduction image quality deteriorates remarkably.
[0018]
In order to solve this problem, a preamplifier may be provided on the rotating drum 1 and a reproduction signal from the rotating head amplified by the preamplifier may be extracted from the rotating drum through a rotary transformer. However, in this case, the following problem occurs. In other words, the gain of the preamplifier is preferably large in order to reduce the influence of the amplifier noise, and is often set to 40 dB or more. However, when doing so, the interchannel separation of the rotary transformer includes a short ring between the channels. However, since it is about 40 dB, the amount of the output reproduction signal of the preamplifier on the rotary drum 1 leaking to the input of the preamplifier for the recording dedicated rotary head (18 in FIG. 4) cannot be ignored.
[0019]
In this case, the accuracy of the above-described rotation control (so-called hill-climbing control) of the capstan 8 using the hill-climbing circuit 19 becomes insufficient, and the recording-purpose rotary head 3L or the like cannot be accurately scanned on the recording track. In order to avoid this problem, it may be possible to separate the rotary transformer connected to the recording-dedicated rotary head and the rotary transformer connected to the reproduction-dedicated rotary head. In addition, the entire apparatus becomes expensive.
[0020]
The present invention has been made in view of the above points, and can perform high-precision tracking control by mounting a preamplifier for a read-only rotating head on a rotating drum without separating a rotary transformer for recording and reproducing. An object is to provide a recording / reproducing apparatus.
[0021]
[Means for Solving the Problems]
In order to achieve the above object, the present invention achieves the first and second rotating heads dedicated to the reproduction of the first and second azimuth angles constituting the pair head, and the first and second azimuth angles constituting the pair head. The recording-purpose third and fourth rotating heads are provided at least on the rotating surface of the rotating drum, and are wound around the outer peripheral side surface of the rotating drum obliquely over a predetermined angle range according to the rotation speed of the capstan. In a magnetic recording / reproducing apparatus having a head mechanism for recording or reproducing or recording and reproducing at the same time with respect to a magnetic tape traveling at a high speed, the first and second rotating heads are provided with the first and second rotating heads. First and second preamplifiers connected to each other and mounted on a rotating drum; reproduction signals of first and second rotating heads taken out from the first and second preamplifiers; A rotary transformer for taking out a reproduction signal obtained by using one of the predetermined rotary heads as a reproduction rotary head among the fourth rotary heads through a dedicated channel, a time difference measuring means, a correction memory, The first and second tracking information generating means, the capstan servo circuit, and the first and second control means, and at the time of normal reproduction after the control by the first and second control means, the time difference Based on the value obtained by correcting the time difference measured by the measuring means with the correction time difference information read from the correction memory, the first tracking information generating means generates the first tracking information, and the first tracking information is generated. Information is supplied to the capstan servo circuit, and control is performed so that a difference between a value obtained by correction and a preset value is minimized.
[0022]
Here, the time difference measuring means measures a time difference between specific signals in the reproduced signals output from the first and second preamplifiers taken out by the rotary transformer. The correction memory stores correction time difference information for correcting the time difference measured by the time difference measuring means. The first tracking information generating means includes a correction memory for storing correction time difference information for correcting the time difference measured by the time difference measuring means, and a first memory generated based on the time difference measured by the time difference measuring means. Output tracking information. The second tracking information generating means obtains the second tracking information based on the RF level of the reproduction signal of one predetermined rotary head taken out by the rotary transformer.
[0023]
The capstan servo circuit controls the rotation of the capstan based on the input tracking information. The first control means supplies the second tracking information from the second tracking information generation means to the capstan servo circuit in a state where the power of the first and second preamplifiers is turned off. Control is performed so that the RF level of the reproduction signal of the other rotary head is maximized. Further, the second control means is configured so that after the control by the first control means, the first tracking information from the first tracking information generation means in a state where the power supplies of the first and second preamplifiers are turned on. Is supplied to the capstan servo circuit so that the difference between the time difference measured by the time difference measuring means and the preset value is minimized, and the time difference measured after the control is stored in the correction memory as a time difference for correction. It is memorized as information.
[0024]
In this invention, when recording is performed by the first and second rotary heads while recording is performed by the third and fourth rotary heads, the reproduction signals of the first and second rotary heads are provided on the rotary drum. Since the first and second preamplifiers are preamplified and input to the rotary transformer, they are considerably larger than the level of the recording signal sent to the third and fourth rotary heads. Even if you jump in, you can reduce the effect.
[0025]
Further, since the level of the reproduction signal preamplified by the first and second preamplifiers provided on the rotary drum is large, the reproduction signal is reproduced from the third and fourth rotary heads in the rotary transformer. If the first and second preamplifiers are not operated, tracking control is performed using only the reproduction signal of one of the third and fourth rotary heads in advance. Therefore, the above interference phenomenon can be eliminated.
[0026]
In the present invention, the time difference obtained from the reproduction signals of the first and second rotary heads in a state where the third and fourth rotary heads accurately scan the recording track after the control by the first control means. Can be obtained as attachment error information of the first and second rotary heads and the third and fourth rotary heads, and this time difference is specific to the rotary drum and is written in the correction memory.
[0027]
In order to achieve the above object, the present invention includes the rotary transformer, the time difference measuring means, the correction memory, the first tracking information generating means, and the capstan servo circuit, and is previously extracted by the rotary transformer. Based on a level detection circuit for detecting the RF level of the reproduction signal of one of the determined rotary heads and a signal obtained by sampling and holding the level detection signal output from the level detection circuit, second tracking information is obtained. With the tracking information generating means 2 and the first and second preamplifiers turned on, the first tracking information from the first tracking information generating means is supplied to the capstan servo circuit to measure the time difference. The first control is performed so that the difference between the time difference measured by the means and the preset value is minimized. And the first and second preamplifiers are turned on and off a plurality of times during the period when the third and fourth rotary heads scan the magnetic tape after the control by the first control means. While alternately repeating, during the power-off period of the first and second preamplifiers, the second tracking information generating means performs the sampling operation to generate the second tracking information, and the second tracking information is captured. A second servo is supplied to the stun servo circuit so that the RF level of the reproduction signal of one of the predetermined rotary heads is maximized, and the measured time difference after the control is stored in the correction memory as correction time difference information. Control means, and during normal playback thereafter, based on the value obtained by correcting the time difference measured by the time difference measuring means with the correction time difference information read from the correction memory. Then, the first tracking information is generated by the first tracking information generation means, the first tracking information is supplied to the capstan servo circuit, and the difference between the value obtained by the correction and the preset value is Control is performed so as to be minimized.
[0028]
In the present invention, after the control by the first control means, during the period when the third and fourth rotary heads scan on the magnetic tape, the second and second preamplifiers are turned off during the power-off period. The second tracking information is generated by performing the sampling operation by the tracking information generating means, and the second tracking information is supplied to the capstan servo circuit so that the RF level of the reproduction signal of one rotary head determined in advance is The rotation of the capstan is controlled so as to be maximized, and the measured time difference after the control is stored in the correction memory as correction time difference information.
[0029]
In order to achieve the above object, according to the present invention, the second control means includes the third and fourth rotary heads at least at three positions of the head portion, the center portion and the last portion of the recording track on the magnetic tape. The first and second preamplifiers are turned off during the scanning period, and the first and second preamplifiers are turned on during the scanning period of the other recording tracks. And In the present invention, tracking control by a capstan servo in consideration of the curvature of the track can be performed.
[0030]
Further, in order to achieve the above object, the second tracking information generating means is configured to perform the first and the second multiple times during the period in which the third and fourth rotary heads scan the magnetic tape. Generating an average value of each value obtained by performing a sampling operation of a signal from the level detection circuit during a power-off period of the second preamplifier, or a weighted value as the second tracking information. To do. In the present invention, even if there are variations due to the curvature of the track in each value obtained by performing the sampling operation of the signal from the level detection circuit during the power-off period of the first and second preamplifiers a plurality of times. Thus, the track shift information can be obtained accurately.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of a magnetic recording / reproducing apparatus according to the present invention. In the figure, the same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted. Note that the read-only rotary head is ahead of the recording-only rotary head in the rotation direction, and the preceding time is about 2 frames, so the mounting height position on the rotary drum 1 is the position of the read-only rotary head. Is attached higher than the recording-only rotary head by a predetermined distance (for example, about 1 mm).
[0032]
In FIG. 1, a reproduction signal processing system having the same configuration as in FIG. 1 is provided on the output side of the read-only rotary heads 4L and 4R and on the output side of the record-only rotary head 5R. Illustration is omitted to avoid it. The operation of the reproduction signal processing system is the same as that of the reproduction signal processing system shown in FIG. In FIG. 1, the recording signal processing system for supplying recording signals to the recording-only rotary heads 3L, 3R, 5L, and 5R is not shown. This is because there is no direct relationship with the present invention.
[0033]
In FIG. 1, the rotary drum 1 is equipped with playback preamplifiers 25L and 25R connected to the playback-only rotary heads 2L and 2R, respectively. The reproduction preamplifiers 25L and 25R are connected to a reproduction signal processing system via rotary transformers 26a and 26c. On the other hand, the recording-only rotary head 3L is connected to the preamplifier 18 via the rotary transformer 26c. This preamplifier 18 is a reproduction preamplifier provided corresponding to the recording dedicated rotary head 3L used for reproduction during editing, and is not connected to the reproduction dedicated rotary head, but is mounted on the rotary drum 1. It has not been.
[0034]
Further, the rotary transformers 26a, 26b, and 26c constitute a single rotary transformer 26 as a whole, and are the first-channel, second-channel, and third-channel rotary transformers among them. The rotary transformer of the channel is connected to the recording dedicated rotary head 3L. That is, the configuration of the rotary transformer used in the present embodiment is the same as that of a conventional magnetic recording / reproducing apparatus, and is not a structure in which the rotary transformer is mechanically divided for recording and reproduction.
[0035]
The reproduction preamplifiers 25L and 25R are configured to be supplied with a power supply voltage from the power supply circuit 27 through the switch circuit 28. The power supply voltage may be supplied using a slip ring, or an AC signal may be supplied through a rotary transformer channel and rectified and supplied on the rotary drum 1.
[0036]
Next, the operation of the present embodiment will be described. First, the CPU 29 turns off the switch circuit 28 and connects the switch circuit 16 to the terminal b side. When the recorded magnetic tape 6 is reproduced in this connected state, the reproduction RF signals of the reproduction-only rotary heads 2L and 2R are not operated because the preamplifiers 25L and 25R are disconnected from the power supply voltage. The reproduction RF signal reproduced from the recording track of the magnetic tape 6 already recorded by the recording dedicated rotary head 3L is supplied to the preamplifier 18 through the rotary transformer 26c and preamplified, whereas it is not supplied to the circuits after 26b. Thereafter, the hill climbing circuit 19 is supplied.
[0037]
At this time, since the preamplifiers 25L and 25R on the rotary drum 1 are inactive, those high level reproduction signals do not jump into the rotary head 3L. Only the reproduced RF signal reproduced from the recording track of the tape 6 is input with high accuracy.
[0038]
As described above, the hill climbing circuit 19 detects the input reproduction RF signal level, supplies a control signal corresponding to the detected level to the capstan servo circuit 20 through the switch circuit 16, and rotates the capstan 8 in the hill climbing circuit 19. Control is performed so that the detected RF level becomes maximum.
[0039]
Here, the level of the RF signal reproduced from the magnetic tape 6 by the rotating head 3L is the same as when the rotating heads 2L, 2R, 3L and 3R are scanning the center position of the recording track (when the tracking error is zero). Shows the maximum value, and the feedback loop comprising the rotary head 3L, the preamplifier 18, the hill climbing circuit 19, the switch circuit 16, the capstan servo circuit 20 and the capstan 8 maximizes the reproduction RF level of the rotary head 3L. By performing so-called hill-climbing control for controlling the rotation of the capstan 8 as described above, it is possible to perform tracking control such that the rotary heads 2L, 2R, 3R, and 3L scan the center position of the recording track. When good tracking control can be realized by the above-described hill-climbing control, the servo of the capstan servo circuit 20 is fixed in this state, and the hill-climbing control is finished.
[0040]
In this state, the CPU 29 controls the switch circuit 28 to be on and switches the switch circuit 16 to the terminal a side. As a result, the reproduction signal processing system starts to operate, and the reproduction RF signal reproduced from the recorded magnetic tape 6 by the reproduction-only rotating heads 2L and 2R is preamplified by the preamplifiers 25L and 25R on the rotating drum 1. Thereafter, the signals are supplied to the time difference measuring circuit 12 through the rotary transformers 26a and 26b, the equalization / quantization circuits 10L and 10R, and the SYNC / ID extraction circuits 11L and 11R, respectively, where two synchronization signals (SYNC) or 2 A time difference between two pieces of address information (ID) is measured.
[0041]
This time difference obtained from the reproduction signal of the rotary heads 2L and 2R in a state where the rotary heads 3L and 3R are accurately scanning the recording track is information on the mounting error between the rotary heads 2L and 2R and the rotary heads 3L and 3R. , Inherent to the rotating drum 1. This time difference is written in the correction memory 13.
[0042]
The above procedure may be performed once at the beginning after the rotating drum assembly is mounted on the set. Next, only the reproduction signals of the reproduction-only rotary heads 2R and 2L are used, the time difference measured by the time difference measurement circuit 12 is corrected by the time difference information stored in the correction memory 13, and the output time difference of the time difference averaging circuit 15 is corrected. Is supplied to the capstan servo circuit 20 through the switch circuit 16, so that the recording-only rotary heads 3L and 3R can automatically perform tracking control with high accuracy so as to scan the recording tracks with almost no track deviation. Thereby, insert edit recording can be performed accurately.
[0043]
As described above, in the present embodiment, the recording-only rotating heads 3L, 3R, 5L, and 5R and the reproducing-only rotating heads 2L, 2R, 4L, and 4R are provided, so that playback can be performed while recording. In this case, the reproduction signals of the reproduction-only rotary heads 2L and 2R are pre-amplified by preamplifiers 25L and 25R provided on the rotary drum 1 and input to the rotary transformers 26a and 26b. Since it is considerably larger than the level of the recording signal sent to the heads 3L and 3R, even when jumping from the rotary transformer to the reproduction signal side, the influence is small.
[0044]
Further, since the level of the reproduction signal preamplified by the preamplifiers 25L and 25R provided on the rotary drum 1 is large, the reproduction signal is recorded in the rotary transformer including the rotary transformers 26a, 26b, and 26c as each channel. The decrease in the accuracy of hill-climbing control due to leakage to the reproduction signal of the dedicated rotary head 3L is because the hill-climbing control is performed using only the reproduction signal of the rotary head 3L with the preamplifiers 25L and 25R not operating in advance. It can be eliminated and accurate tracking control becomes possible.
[0045]
Next, a second embodiment of the present invention will be described. FIG. 2 shows a configuration diagram of a second embodiment of a magnetic recording / reproducing apparatus according to the present invention. In the figure, the same components as those in FIG. The embodiment shown in FIG. 2 is characterized in that the time difference is measured at the beginning, center, and end of the recording track in consideration of the bending of the recording track, and the pulse generation circuit 32 and the sampling hold (S / S H) A circuit 33 is provided.
[0046]
Next, the operation of this embodiment will be described with reference to the time chart of FIG. The CPU 31 controls the pulse generation operation of the pulse generation circuit 32 and controls the switching of the switch circuit 34. The pulse generation circuit 32 is a drum pulse which is generated by a known drum pulse generation means (not shown) and is a square wave whose polarity is inverted every rotation of the rotating drum 1 in synchronization with the rotation phase of the rotating drum 1. 3 is received as an input, and based on the output control signal of the CPU 31, a pulse S1 shown in FIG. 3A is generated and supplied to the switch circuit 28 as a switching pulse to control the switching, and the S / H circuit 33 is sampled. It is supplied as a pulse to control its operation.
[0047]
The above-mentioned pulse S1 is a total of three fixed intervals (for example, 100 μs) corresponding to a period during which the recording-only rotary heads 3L and 3R scan (trace) the recorded portion of the recorded magnetic tape 6 at the head portion, the center portion and the end portion of the recording track. This is a high level pulse. The switch circuit 28 is turned off during the high level period of the pulse S1, and is turned on during the low level period. The S / H circuit 33 performs a sample operation during the high level period of the pulse S1, and performs a hold operation during the low level period.
[0048]
As a result, the preamplifiers 25L and 25R provided on the rotary drum 1 are scanned by the recording-only rotary heads 3L and 3R at the three locations of the recording track of the recorded magnetic tape 6: the first portion, the central portion, and the last portion. When the switch circuit 28 is turned off, the power supply voltage from the power supply circuit 27 is cut off, so that the switch circuit 28 is not operated, and the power supply voltage is supplied during the other periods. From the preamplifiers 25L and 25R, as shown in FIG. 3B, the recording-only rotary heads 3L and 3R scan the head portion, the center portion, and the end portion of the recording track of the recorded magnetic tape 6 at three locations. During each period, the reproduction RF signal is not output, and the input reproduction RF signal is amplified and extracted only during other periods.
[0049]
The reproduction RF signal S2 output from the preamplifiers 25L and 25R shown in FIG. 3B is output to the reproduction signal processing system through the rotary transformers 26a and 26b, and is simultaneously reproduced in parallel from the two tracks by the time difference measuring circuit 12. The time difference between the two synchronization signals (SYNC) or address information (ID) is measured. The measured time difference is held in the time difference memory 14 and then averaged by the time difference averaging circuit 15.
[0050]
As in the prior art, the switch circuit 34 is initially connected to the terminal a based on a control signal from the central processing unit (CPU) 31, and the average time difference from the time difference averaging circuit 15 is transferred to the capstan servo circuit 20. Then, a servo for controlling the rotation of the capstan 8 is applied so that the difference between the average time difference and a value near zero set in advance is minimized, and the running control of the magnetic tape 6 is performed, and the rotary heads 2L and 2R are controlled. Tracking control is performed. Thereafter, when the average time difference reaches a predetermined value near zero, the CPU 31 switches the switch circuit 34 to the terminal b side, and performs capstan servo based on the signal from the hill climbing circuit 19.
[0051]
During a period in which the switch circuit 34 is switched and connected to the terminal b side, the preamplifiers 25L and 25R are not operating in the reproduction RF signal reproduced by the rotary head 3L, as indicated by S3 in FIG. In each period in which the recording-only rotating heads 3L and 3R scan the head portion, the center portion, and the last portion of the recording track of the recorded magnetic tape 6, the reproduction RF signals from the preamplifiers 25L and 25R are reproduced RF of the rotation head 3L. Since it does not jump into the signal, it can be obtained at an accurate level according to the tracking error, and the reproduced RF signal from the preamplifiers 25L and 25R has a waveform that jumps in as noise during periods other than the above three locations.
[0052]
The reproduction RF signal S3 reproduced by the rotary head 3L is supplied to the S / H circuit 33 through the rotary transformer 26c, the preamplifier 18 and the hill climbing circuit 19, and is sampled here during the high level period of the pulse S1. This sampling period is a period in which the recording-only rotary heads 3L and 3R described above scan the head portion, the center portion, and the end portion of the recording track of the recorded magnetic tape 6. The S / H circuit 33 samples the reproduction RF signal at an accurate level according to the tracking error without the influence of the reproduction RF signal from the preamplifiers 25L and 25R in the sampling period, and the capstan servo through the switch circuit 34. The capstan servo circuit 20 is hill-climbed and controlled so that the sampling value (RF level) at which the rotation of the capstan 8 is detected by the S / H circuit 33 is maximized.
[0053]
Here, the sampling value processing described above may average a plurality of measurement sampling values between one track, and the beginning and end of the recording track are generally larger in curvature than the center portion, so that recording is performed. It is also possible to perform hill climbing control so that the sampling values at the beginning and end of the track are weighted less and added to the sampling value at the center, and the maximum is obtained.
[0054]
When the above hill climbing control is converged, the CPU 31 writes the measurement time difference of the time difference measurement circuit 12 at that time in the correction memory 13. The measurement time difference at this time is not only the rotation head mounting error but also the time difference including the bending of the recording track.
[0055]
Thereafter, during normal reproduction, the CPU 31 does not generate the pulse S1 from the pulse generation circuit 32, the switch circuit 28 is always turned on, the preamplifiers 25L and 25R are always in an operating state, and only the reproduction signals of the reproduction-only rotary heads 2R and 2L are received. The time difference measured by the time difference measuring circuit 12 is corrected with the time difference information stored in the correction memory 13, and the output time difference of the time difference averaging circuit 15 is supplied to the capstan servo circuit 20 through the switch circuit 34. The recording-only rotary heads 3L and 3R can automatically perform tracking control with high accuracy so as to scan the recording track with almost no track deviation. Thereby, insert edit recording can be performed accurately.
[0056]
In this embodiment, since the time difference written in the correction memory 13 can be measured while both the time difference measuring circuit 12 and the hill climbing circuit 19 are operated, the measurement time can be shorter than that in the first embodiment.
[0057]
Note that the present invention is not limited to the above-described embodiment. For example, in the second embodiment, the S / H circuit 33 is provided from three locations, that is, the first portion, the center portion, and the last portion of one recording track. However, it is a matter of course that four or more reproduction RF signals may be sampled.
[0058]
【The invention's effect】
As described above, according to the present invention, the reproduction signal preamplified by the first and second preamplifiers generated when the first and second preamplifiers are provided on the rotating drum is generated in the rotary transformer. The deterioration of the tracking control accuracy due to leakage of the reproduction signals of the third and fourth rotary heads is caused by preliminarily deactivating the first and second preamplifiers and the rotation of one of the third and fourth rotary heads. By performing tracking control using only the reproduction signal, the above interference phenomenon can be eliminated, and from this, the amount of deviation in the track width direction between the first and second rotary heads and the third and fourth rotary heads can be accurately measured. This can improve the accuracy of tracking control.
[0059]
Further, according to the present invention, since the interference phenomenon can be eliminated, the rotary transformers for the first and second rotary heads dedicated to reproduction and the rotary transformers of the third and fourth rotary heads dedicated to recording are used. Since it is not necessary to divide, it is possible to prevent the rotating drum and the entire apparatus from being enlarged.
[0060]
Furthermore, according to the present invention, each value obtained by performing the sampling operation of the signal from the level detection circuit during the power-off period of the first and second preamplifiers a plurality of times varies due to the curvature of the track. Even if there is an error, the track deviation information can be obtained accurately, so that the S / N of the reproduction signal can be improved and the tracking control can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a first embodiment of a device of the present invention.
FIG. 2 is a configuration diagram of a second embodiment of the device of the present invention.
FIG. 3 is a time chart for explaining the operation of FIG. 2;
FIG. 4 is a configuration diagram of an example of a conventional apparatus.
FIG. 5 is a characteristic explanatory diagram of a hill-climbing circuit.
FIG. 6 is a connection explanatory diagram of a rotary transformer, a rotary head, and a preamplifier.
[Explanation of symbols]
1 Rotating drum
2L, 2R, 4L, 4R Read-only rotating head
3L, 3R, 5L, 5R Recording dedicated rotary head
6 Recorded magnetic tape
8 Capstan
12 Time difference measurement circuit
13 Correction memory
14 Time difference memory
15 Time difference averaging circuit
16, 28, 34 Switch circuit
18 Preamplifier
20 Capstan servo circuit
25L, 25R Preamplifier mounted on rotating drum
26a, 26b, 26c Rotary transformer
29, 31 Central processing unit (CPU)
33 Sampling hold (S / H) circuit

Claims (4)

First and second rotation heads dedicated to reproduction of the first and second azimuth angles constituting the pair heads, and third and fourth rotations dedicated to recording of the first and second azimuth angles constituting the pair heads A magnetic tape that runs at a speed corresponding to the rotational speed of the capstan while being obliquely wound around the outer peripheral side surface of the rotary drum over a predetermined angular range. A magnetic recording / reproducing apparatus comprising a head mechanism for performing recording or reproduction or recording and reproduction simultaneously by the first to fourth rotating heads,
First and second preamplifiers connected to the first and second rotary heads and mounted on the rotary drum;
The reproduction signal of the first and second rotary heads taken out from the first and second preamplifiers and one of the third and fourth rotary heads, which is determined in advance, is used as a reproduction rotary head. And a rotary transformer that takes out the playback signal obtained through each dedicated channel,
A time difference measuring means for measuring a time difference between specific signals in each reproduction signal output from the first and second preamplifiers taken out by the rotary transformer;
A correction memory for storing correction time difference information for correcting the time difference measured by the time difference measuring means;
First tracking information generating means for outputting first tracking information generated based on the time difference measured by the time difference measuring means;
Second tracking information generating means for obtaining second tracking information based on an RF level of a reproduction signal of the predetermined one rotary head taken out by the rotary transformer;
A capstan servo circuit for controlling the rotation of the capstan based on input tracking information;
With the first and second preamplifiers turned off, the second tracking information from the second tracking information generating means is supplied to the capstan servo circuit to supply the predetermined one rotation. First control means for controlling the RF level of the reproduction signal of the head to become maximum;
After the control by the first control means, the first tracking information from the first tracking information generation means is supplied to the capstan servo circuit in a state where the power of the first and second preamplifiers is turned on. And control so that the difference between the time difference measured by the time difference measuring means and a preset value is minimized, and the measured time difference after the control is stored in the correction memory as the time difference information for correction. A second control means for storing, and during normal playback thereafter, based on a value obtained by correcting the time difference measured by the time difference measuring means with the correction time difference information read from the correction memory. The first tracking information generating means generates the first tracking information, and supplies the first tracking information to the capstan servo circuit. Magnetic recording and reproducing apparatus, characterized in that the difference between the preset value and the obtained corrected value is controlled to be minimized. First and second rotation heads dedicated to reproduction of the first and second azimuth angles constituting the pair heads, and third and fourth rotations dedicated to recording of the first and second azimuth angles constituting the pair heads A magnetic tape that runs at a speed corresponding to the rotational speed of the capstan while being obliquely wound around the outer peripheral side surface of the rotary drum over a predetermined angular range. A magnetic recording / reproducing apparatus comprising a head mechanism for performing recording or reproduction or recording and reproduction simultaneously by the first to fourth rotating heads,
First and second preamplifiers connected to the first and second rotary heads and mounted on the rotary drum;
The reproduction signal of the first and second rotary heads taken out from the first and second preamplifiers and one of the third and fourth rotary heads, which is determined in advance, is used as a reproduction rotary head. And a rotary transformer that takes out the playback signal obtained through each dedicated channel,
A time difference measuring means for measuring a time difference between specific signals in each reproduction signal output from the first and second preamplifiers taken out by the rotary transformer;
A correction memory for storing correction time difference information for correcting the time difference measured by the time difference measuring means;
First tracking information generating means for outputting first tracking information generated based on the time difference measured by the time difference measuring means;
A level detection circuit for detecting an RF level of a reproduction signal of the predetermined rotary head taken out by the rotary transformer;
Second tracking information generating means for obtaining second tracking information based on a signal obtained by sampling and holding the level detection signal output from the level detection circuit;
A capstan servo circuit for controlling the rotation of the capstan based on input tracking information;
With the power supplies of the first and second preamplifiers turned on, the first tracking information from the first tracking information generating means is supplied to the capstan servo circuit and measured by the time difference measuring means. First control means for controlling the difference between the set time difference and a preset value to be minimum;
After the control by the first control means, the first and second preamplifiers are turned on and off a plurality of times while the third and fourth rotary heads are scanning the magnetic tape. Are alternately repeated, and during the power-off period of the first and second preamplifiers, the second tracking information generating means performs the sample operation to generate the second tracking information, and the second tracking information is generated. Tracking information is supplied to the capstan servo circuit so that the RF level of the reproduction signal of the predetermined rotary head is maximized, and the measured time difference after the control is stored in the correction memory. A second control unit that stores the time difference information for correction, and reads the time difference measured by the time difference measuring unit from the correction memory during normal playback thereafter. The first tracking information generating means generates the first tracking information based on the value obtained by correcting with the correction time difference information that has been issued, and the first tracking information is sent to the capstan servo circuit. A magnetic recording / reproducing apparatus, wherein the control is performed so that the difference between the value obtained by the correction and the preset value is minimized. The second control means is configured such that the third and fourth rotary heads scan at least three positions of the head portion, the center portion, and the last portion of the recording track on the magnetic tape. 3. The magnetic recording according to claim 2, wherein the power supply of the second preamplifier is turned off, and the power supply of the first and second preamplifiers is turned on during a period during which the other recording track is scanned. Playback device. The second tracking information generation means is configured to perform a plurality of power off periods of the first and second preamplifiers during a period in which the third and fourth rotary heads scan the magnetic tape. The average value of each value obtained by performing the sampling operation of the signal from the level detection circuit or a value obtained by weighting and adding is generated as the second tracking information. Magnetic recording / reproducing device.

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