JP2000354222A - Magnetic reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To process an information signal by accurately detecting the information signal with a maximum level that is reproduces with a reproduction head reaching a completely on-track state among information signals recorded in a long play mode. SOLUTION: An envelope detection circuit 110, an integration circuit 120, and a sample-and-hold circuit 130 apply integral processing to an envelope of a reproduction output for each recording track and sample and hold the output. First, second delay circuits 140, 150 and an arithmetic circuit 155 generate an arithmetic output with a large level difference corresponding to each recording track on the basis of three sample and hold outputs. A maximum hold circuit 160, a 1/2 circuit 165, a comparator 170 and a senary counter 180 apply on/off control to a mute switch 200 in a timing when a maximum ari thmetic output is detected to select only an information signal with a maximum level and an information data reproducing processing system 3 of a post-stage processes the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to, for example, D-VHS
The present invention relates to a magnetic reproducing apparatus suitable for a magnetic recording / reproducing apparatus for recording / reproducing an information signal based on the (registered trademark) system, and particularly to information recorded in a long play mode such as 3 ×, 5 × and 7 × speed. And a magnetic reproducing apparatus capable of reproducing at a precise timing.

[0002]

2. Description of the Related Art A D-VHS magnetic recording / reproducing apparatus for digitally recording an information signal on a magnetic tape based on a D-VHS recording format has been known. This magnetic recording / reproducing apparatus is provided with a long play mode such as 3 ×, 5 ×, 7 ×, etc.
A magnetic tape (420) capable of recording information signals for 7 hours when recording at a normal recording speed (standard mode)
When recording is performed in the long play mode at 7 × speed using a minute tape), information signals for 49 hours can be recorded.

[0003] Specifically, this magnetic recording / reproducing apparatus includes:
As shown in FIG. 6, two recording / reproducing heads A and
B, for example, at the time of recording in the 7 × speed long play mode, the rotation speed of the rotating drum 300 is controlled to the same rotation speed as in the standard mode, and the running speed of the magnetic tape is 1 in the standard mode.
The traveling speed is controlled to a traveling speed of / 7.

FIG. 7A shows a drum flip-flop signal (DFF signal: a repetitive signal that goes high and low every time the rotating drum 300 makes a half turn) during recording in the 7 × speed long play mode, This is a time chart showing the recording / reproducing heads A and B for tracing on the tape and the timing at which the recording / reproducing heads A and B are turned on. As can be seen from FIG. After the recording / reproducing head A is turned on at the timing when the recording / reproducing head A traces on the magnetic tape, the recording / reproducing heads A and B are turned off while the rotating drum 300 rotates three times. After the rotation, the recording / reproducing head B is turned on at the timing when the recording / reproducing head B traces on the magnetic tape.

More specifically, after the magnetic tape is traced by the recording / reproducing head A to record information signals, the recording / reproducing heads A and B are turned off while the rotary drum 300 rotates three times to perform an empty trace. After the three rotations, the operation of turning on the recording / reproducing head B and recording the information signal by the recording / reproducing head B is repeatedly performed.

Thus, the rotating drum 300 is rotated three times while the rotating speed of the rotating drum 300 is the same as that in the standard mode, and the running speed of the magnetic tape is 1/7 that in the standard mode. The magnetic tape was alternately traced by each of the recording / reproducing heads A and B every half, and the information amount was reduced to 1/7 so that adjacent recording tracks had different azimuth angles as shown in FIG. The recording of the information signal is performed.

FIG. 7 (b) shows the reproduction output level of the information signal recorded in the long play mode at 7 × speed, the DFF signal, and the recording / reproducing heads A and B for tracing the recording track. 6 is a time chart showing an output ratio of information signals reproduced by reproduction heads A and B, and presence or absence of signal processing. When reproducing the information signal recorded in the 7 × speed long play mode, the rotating drum 300
Is controlled to the same rotational speed as in the standard mode, and the running speed of the magnetic tape is 1 in the standard mode.
/ 7. Also, the rotating drum 300
The recording / reproducing heads A and B are turned on all the time.

In this state, the information signals recorded on the magnetic tape are alternately traced and reproduced by the recording and reproducing heads A and B. The recording track A recorded by the recording and reproducing head A shown in FIG. If the recording / reproducing head A is traced in an on-track state (during just track), the output ratio is "1" as shown in FIG.
And the maximum reproduction output is obtained.

Next, the running of the magnetic tape is controlled so as to advance by a distance of 1/7 of that in the standard mode, whereby the recording / reproducing head B traces 6/7 of the recording track A. At the same time, 1/7 of the recording track B adjacent to the recording track A is traced. As described above, since the recording and reproducing heads A and B have different azimuth angles, the information signal of the recording track A recorded by the recording and reproducing head A is not reproduced by the recording and reproducing head B at the time of recording. Only the information signal of the recording track B recorded by the recording / reproducing head B is reproduced by the recording / reproducing head B. Therefore, in this case, 1 /
The reproduction output of the recording track B on which No. 7 is traced is obtained, and the output ratio becomes "1/7", and the lowest reproduction output is obtained.

Next, the running of the magnetic tape is controlled so as to advance by a distance of 1/7 of that in the standard mode. With this operation, the recording / reproducing head A traces 5/7 of the recording track A. At the same time, 2/7 of the recording track B adjacent to the recording track A is traced. Therefore, from the difference in the azimuth angle, 5 /
A reproduction output of the recording track A on which No. 7 is traced is obtained, and the output ratio is "5/7" (the reproduction output level is 5/7 of the maximum value).

Next, when the running of the magnetic tape is further controlled so as to advance by a distance of 1/7 of that in the standard mode, the recording / reproducing head B moves the magnetic tape 4/4 of the recording track A.
7 is traced, and 3/7 of the recording track B adjacent to the recording track A is traced. As a result, a reproduction output of the recording track B in which 3/7 is traced is obtained, and the output ratio is "3/7" (the reproduction output level is 3/7 at the maximum).

Next, when the running of the magnetic tape is further controlled so as to advance by a distance of 1/7 of that in the standard mode, the recording / reproducing head A makes 3/3 of the recording track A.
7 is traced, and 4/7 of the recording track B adjacent to the recording track A is traced. As a result, a reproduction output of the recording track A in which 3/7 is traced is obtained, and the output ratio is "3/7" (the reproduction output level is 3/7 of the maximum value).

Next, when the traveling of the magnetic tape is further controlled so as to advance by a distance of 1/7 of that in the standard mode, the recording / reproducing head B causes the recording tape A to travel 2/1/2 of the recording track A.
7 is traced, and 5/7 of the recording track B adjacent to the recording track A is traced. As a result, a reproduction output of the recording track B in which 5/7 is traced is obtained, and the output ratio is “5/7” (the reproduction output level is 5/7 at the maximum).

Next, when the traveling of the magnetic tape is further controlled so as to advance by a distance 1/7 of that in the standard mode, the recording / reproducing head A causes the recording / reproducing head A to move 1 / of the recording track A.
7 is traced, and 6/7 of the recording track B adjacent to the recording track A is traced. As a result, a reproduction output of the recording track A in which 1/7 is traced is obtained, and the output ratio becomes "1/7" (the reproduction output level becomes 1/7 of the maximum value).

Next, when the running of the magnetic tape is further controlled so as to advance by 1/7 of the distance in the standard mode, the recording track B adjacent to the recording track A is traced by the recording / reproducing head B in the just track state. Is done. As a result, it is possible to obtain a reproduction output with the output ratio “1”.

That is, at the time of this reproduction, the rotating drum 3
The recording track is traced in a just-track state by one of the recording / reproducing heads A or B at a rate of once every two rotations of 00. For this reason, while the rotating drum 300 makes four rotations, the output ratio becomes “1” →
"1/7" → "5/7" → "3/7" → "3/7" →
It changes in the order of “5/7” → “1/7” → “1”.

The conventional magnetic recording / reproducing apparatus sequentially compares the thus-changed reproduction output levels, and detects an information signal of the maximum reproduction output level, that is, an information signal whose output ratio is "1" ( Only the information signal having the maximum reproduction output level is reproduced by performing predetermined information data reproduction processing in a subsequent stage such as A / D conversion processing, error correction processing, D / A conversion processing, and the like. Supply to the monitor device. Thus, the information signal recorded in the 1/7 × long play mode can be reproduced and displayed on the monitor.

[0018]

However, in the conventional magnetic recording / reproducing apparatus, when reproducing the information signal recorded in the long play mode, the information for a predetermined period sequentially reproduced by the recording / reproducing heads A and B is used. Among the signals, the information signal having the maximum reproduction output level (in the example of reproducing the information signal recorded in the 7 × long play mode, the information signal obtained during three and a half rotations of the rotating drum 300) is used. Since detection (maximum value detection) is performed, the following problem occurs.

That is, in the example in which the information signal recorded in the 7 × speed long play mode is reproduced, the information signal having the maximum reproduction output level among the information signals obtained while the rotating drum 300 rotates three and a half times. Is an information signal whose output ratio is "1", and the next information signal whose reproduction output level is the next is an information signal whose output ratio is "5/7". In addition, there has been a problem that erroneous detection occurs in the detection of the maximum value. When this erroneous detection occurs, S / S signals other than the information signal of the reproduction output level
An information signal having a poor N-ratio is subjected to the information data reproduction processing, thereby causing a problem of reproduction.

Further, the information data reproducing process at the subsequent stage needs to be performed using a synchronous signal having a timing that matches the phase of the reproduced information signal. For this reason, the phase locked loop circuit (PLL circuit) reproduces the information data. The phase of the reproduced information signal is detected to form a synchronization signal at a timing that matches the phase of the reproduced information signal.
Due to the difference in the azimuth angle, the output ratio of the information signal before and after the information signal having the output ratio of “1” is as small as “1/7”.
Since the PLL circuit detects the phase error of the reproduced information signal and forms the synchronization signal, the response becomes unstable when the output ratio decreases to "1/7". The unstable response of the PLL circuit does not recover the information signal having the output ratio "1" in a short period of time until the information data reproducing process. There has been a problem that information data is reproduced with a stable synchronization signal and is not reproduced accurately.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to accurately detect and reproduce an information signal having a maximum reproduction output level from information signals recorded and reproduced in a long play mode. It is another object of the present invention to provide a magnetic reproducing apparatus capable of improving the responsiveness of a PLL circuit and reproducing an information signal with accurate timing synchronization response characteristics even when the reproduction output level is reduced.

[0022]

According to a first aspect of the present invention, there is provided a magnetic reproducing apparatus according to the present invention, wherein a tape-shaped magnetic recording medium has a normal traveling speed of 1 / n, and different azimuth angles provided on a rotating drum. The information recorded obliquely on the magnetic recording medium by the at least two recording heads so that adjacent recording tracks have different azimuth angles at a rate of once every n / 2 rotations of the rotary drum. Assuming a magnetic reproducing apparatus (n is an odd number of 3 or more) for reproducing the data, the following characteristic means are provided as means for solving the above-mentioned problem.

That is, the magnetic reproducing apparatus is provided on the rotating drum with running control means for controlling the running speed of the magnetic recording medium to 1 / n of the normal speed as in the case of recording information. At least two reproducing heads having azimuth angles corresponding to the azimuth angles of the heads, rotation control means for controlling the rotation of a rotary drum provided with each of the reproducing heads at the same rotational speed as when recording the information, and Signal processing means for performing predetermined signal processing on reproduction information reproduced by a head, and supply / non-supply control means for controlling supply / non-supply of reproduction information supplied from each of the reproduction heads to the signal processing means And

In addition to these means, an envelope detecting means for detecting an envelope of the reproduction information reproduced by each of the reproducing heads, and an integrating means for performing an integration process for each envelope detection output from the envelope detecting means. And sequentially adding / subtracting three consecutive integrated outputs among the integrated outputs sequentially supplied from the integrating means, detecting a timing at which the output becomes the maximum among the n consecutive integrated outputs, and Control means for controlling the supply / non-supply of the reproduction information in the supply / non-supply control means with reference to the timing when the maximum value is obtained.

The magnetic reproducing apparatus according to the first aspect of the present invention detects an envelope for each information of each recording track, and integrates this envelope detection output, so that an integrated output is output to each recording track. Get the corresponding information level. Accordingly, even when the envelope detection output has various shapes such as a pincushion shape, a drum shape, and a taper shape, the difference in the shape of each envelope detection output can be absorbed by the integration process (the shape is averaged). It is possible to detect an accurate information level for each recording track. Therefore, in the control means, of the continuous n integrated outputs,
The timing at which the output becomes maximum can be accurately detected.

Further, the control means controls the reproduction head so that the reproduction information is supplied from the reproduction heads to the signal processing means at the timing when the output of the continuous n integration outputs is maximized. By controlling the supply / non-supply control means, only the reproduction information having the maximum value among the reproduction information reproduced by each reproduction head can be accurately supplied to the signal processing means. For this reason, it is possible to prevent the inconvenience of reproducing information having a poor S / N ratio being supplied to the signal processing means and causing a malfunction.

Next, in a magnetic reproducing apparatus according to the present invention, a tape-shaped magnetic recording medium is set to a normal traveling speed of 1 / n, and at least two azimuth angles different from each other provided on a rotating drum. One recording head reproduces information obliquely magnetically recorded on a magnetic recording medium such that adjacent recording tracks have different azimuth angles once every time the rotary drum rotates n / 2 times. Assuming a magnetic reproducing apparatus (n is an odd number of 3 or more) to perform, the following characteristic means are provided as means for solving the above-described problems.

That is, the magnetic reproducing apparatus is provided on the rotating drum with running control means for controlling the running speed of the magnetic recording medium to 1 / n of the normal speed as in the case of recording information. At least two reproducing heads having azimuth angles corresponding to the azimuth angles of the heads, rotation control means for controlling the rotation of a rotary drum provided with each of the reproducing heads at the same rotational speed as when recording the information, and It has signal processing means for performing predetermined signal processing on the reproduction information reproduced by the head, and envelope detection means for detecting the envelope of the reproduction information reproduced by each reproduction head.

Further, together with these means, an integrating means for performing an integration process for each envelope detection output corresponding to one recording track from the envelope detecting means, and a continuous output among the integrated outputs sequentially supplied from the integrating means. A timing detecting means for sequentially adding and subtracting the three integrated outputs thus obtained to detect a timing at which the output becomes maximum among the continuous n integrated outputs, and a clock having a frequency corresponding to an input signal to the signal processing means. And a phase error signal indicating a phase error between a clock from the clock generation unit and reproduction information reproduced by each of the reproduction heads, to the clock generation unit with first or second response characteristics. The phase error output means to be input, and the timing at which the output detected by the timing detection means becomes maximum is used as a reference. And a response characteristic switching means for switching between a first response characteristic and a second response characteristic in the phase error output means Te.

In such a magnetic reproducing apparatus, the response characteristic switching means includes: a first response characteristic in the phase error output means;
Switching between the second response characteristic and the phase error output means outputs a phase error signal based on each response characteristic.

A time constant for determining the first response characteristic for the reproduction information at the maximum value level and a time constant for determining the second response characteristic for the reproduction information other than the reproduction information at the maximum value level are provided. By switching the time constant, it is possible to perform stable lock signal processing without being affected by the level of the reproduction information.

Next, in a magnetic reproducing apparatus according to the present invention, a tape-shaped magnetic recording medium is set to a normal traveling speed of 1 / n, and at least two azimuth angles different from each other provided on a rotating drum. One recording head reproduces information obliquely magnetically recorded on a magnetic recording medium such that adjacent recording tracks have different azimuth angles once every time the rotary drum rotates n / 2 times. Assuming a magnetic reproducing apparatus (n is an odd number of 3 or more) to perform, the following characteristic means are provided as means for solving the above-described problems.

That is, the magnetic reproducing apparatus is provided on the rotating drum with running control means for controlling the running of the magnetic recording medium to 1 / n of the normal running speed as in the case of recording information. At least two reproducing heads having azimuth angles corresponding to the azimuth angles of the heads, rotation control means for controlling the rotation of a rotary drum provided with each of the reproducing heads at the same rotational speed as when recording the information, and Signal processing means for performing predetermined signal processing on reproduction information reproduced by a head, and supply / non-supply control means for controlling supply / non-supply of reproduction information supplied from each of the reproduction heads to the signal processing means And

In addition to these means, an envelope detecting means for detecting an envelope of the reproduction information reproduced by each of the reproducing heads, and an integrating means for performing an integration process for each envelope detection output from the envelope detecting means. A timing detecting means for sequentially adding and subtracting three consecutive integrated outputs among the integrated outputs sequentially supplied from the integrating means, and detecting a timing at which the output becomes maximum among the n consecutive integrated outputs; Clock generating means for supplying a clock having a frequency corresponding to an input signal to the signal processing means; and a phase error signal indicating a phase error between the clock from the clock generating means and the reproduction information reproduced by each reproduction head. Phase error output means for inputting the clock signal with the first or second response characteristic to the clock generation means; The supply / non-supply of the reproduction information is controlled by the supply / non-supply control unit with reference to the timing at which the output detected by the detection unit is maximum, and the first response characteristic of the phase error output unit is Control means for switching between the second response characteristic and the second response characteristic.

In such a magnetic reproducing apparatus, the supply / non-supply control means supplies only the maximum level of reproduction information to the signal processing means for signal processing, and the control means controls the first response characteristic of the phase error output means. Switches the second response characteristic. As a result, the reproduced information at the maximum value level can be signal-processed with a stable clock.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Embodiment> A magnetic reproducing apparatus according to the present invention has a D
The present invention can be applied to a magnetic reproducing apparatus that reproduces a video signal recorded in a long play mode of the VHS system.
As the long play mode of the D-VHS system, for example, three times speed, five times speed, and seven times speed are known.
The description will be made by taking as an example the operation of reproducing the video signal recorded in the 7 × speed long play mode described with reference to FIG. The technical concept of the playback operation of the video signal recorded in the 3 × and 5 × long play modes is the same as that of the video signal recorded in the 7 × long play mode described below. See the description below.

"Overall Configuration of First Embodiment" First, FIG. 1 is a schematic configuration diagram of a magnetic reproducing apparatus according to a first embodiment of the present invention. As can be seen from FIG. 1, the magnetic reproducing apparatus according to the first embodiment reproduces the video signal recorded on the magnetic tape in the 7 × long play mode, and reproduces the video signal with the reproducing head 1. A preamplifier 2 for amplifying the output video signal with a predetermined gain and outputting the video signal, a video process processing system 3 for performing a predetermined video process process on the video signal from the preamplifier 2 and reproducing the video signal, and a video signal for a predetermined period from the preamplifier 2 Among them, the video signal having the maximum reproduction output level is detected, and only the video signal having the maximum reproduction output level is supplied to the video process processing system 3 at the subsequent stage. And a maximum value detection system 4 for controlling supply / non-supply of the video signal to the video signal.

"Configuration of Reproducing Head 1"
Reproducing heads A and B having different azimuth angles face the rotating drum so that recording heads having different azimuth angles can alternately correspond to recording tracks recorded on the magnetic tape during recording. The arrangement is arranged.

[Configuration of Video Process Processing System 3] The video process processing system 3 is digitized by an A / D converter 230 for digitizing a video signal supplied as an analog signal from the preamplifier 2 and an A / D converter 230. Equalizer 250 for performing a predetermined equalizing process on the obtained video signal, and a demodulation circuit 270 (1 + D) for performing a demodulation process corresponding to the predetermined modulation process performed on the equalized video signal during recording.
And an error correction circuit 290 (ECC circuit) for performing error correction processing on the video signal demodulated by the demodulation circuit 270.
And a phase locked loop circuit 5 (PLL) for forming a clock to be supplied to each section of the video processing system 3.
Circuit).

The PLL circuit 5 includes an A / D converter 230
And the voltage variable oscillator 260 (VC
A phase error detection circuit 240 for detecting a phase error by comparing the phase of the clock from O), and performing a predetermined filtering process on a phase error detection output from the phase error detection circuit 240 with a predetermined time constant. A loop filter 220 for forming an error voltage indicating the phase error, and a clock having a phase for canceling the phase error detected by the phase error detection circuit 240 based on the error voltage from the loop filter 220 to form the equalizer 250 , A demodulation circuit 270, a variable voltage oscillator 260 (VCO) which supplies the ECC circuit 290, and the like.

"Configuration of Maximum Value Detection System 4"
Is provided between the preamplifier 2 and the A / D converter 230 so that only the video signal showing the maximum value among the video signals reproduced by the reproducing head 1 is supplied to the A / D converter 230. Mute switch 200 on / off controlled
And an envelope detection circuit 110 for detecting an envelope of a video signal for each recording track from the preamplifier 2.
And a drum flip-flop signal (DFF) that repeats a high level and a low level every time the reproducing head 1 makes a half turn.
And an edge detection circuit 125 for detecting a rising edge and a falling edge of the signal.

The maximum value detection system 4 further includes a delay circuit 135 (DL) that performs a predetermined delay processing described later on the edge detection output from the edge detection circuit 125 and outputs the result.
The edge detection output delayed by the delay circuit 135 is used as a reset pulse, and the envelope from the envelope detection circuit 110 during the half rotation (180 degree rotation) of the reproducing head 1 until the reset pulse is supplied. It has an integrating circuit 120 for integrating the detected output, and a sample and hold circuit 130 (S / H) for sampling and holding the integrated output from the integrating circuit 120 and outputting the sampled output.

The maximum value detection system 4 delays the sample-and-hold output from the S / H circuit 130 for the time required for the reproducing head 1 to make a half turn (180 ° rotation = 1/60 sec). First delay circuit 140 (1/60)
secDL) and the sample-and-hold output from the S / H circuit 130 is subjected to a delay process for the time required for the reproducing head 1 to make one rotation (360 ° rotation = 1/30 sec).
And the current sample-hold output and the second delay circuit from the sample-hold output that has been subjected to the delay processing for the half-turn of the reproducing head 1 by the first delay circuit 140 and the delay circuit 150 (1/30 secDL). The arithmetic circuit 155 performs a subtraction process on the sample-and-hold output that has been delayed by the rotation time of the reproduction head 1 by 150.

The maximum value detection system 4 includes an arithmetic circuit 1
Max hold circuit 160 (MAX HOLD) for holding and outputting the maximum value of the arithmetic output from 55, and す る for adjusting the maximum value hold output from max hold circuit 160 to レ ベ ル and outputting it Circuit 1
65, the inverted output value of the maximum value hold output (1/2 maximum value hold output) whose level has been adjusted by the 1/2 circuit 165, and the sample hold output from the arithmetic circuit 155, and outputs this comparison output. Comparator 170
When the value of the operation output from the operation circuit 155 is larger than the value of the １ ／ maximum value hold output whose polarity has been inverted, the comparison output output from the comparator 170 is used as a reset pulse, and the DFF signal And a hexadecimal counter 180 that outputs a switching pulse for turning on the mute switch 200 at the timing when the DFF signal is counted six times.

[Operation of First Embodiment] In the magnetic reproducing apparatus of the first embodiment having such a configuration, when the reproducing operation is started, the reproducing head 1 rotates at the same rotational speed as during recording. , And the running of the magnetic tape is controlled at the same running speed as that during recording. in this case,
Since this is an example in which a video signal is recorded in the 7 × speed long play mode at the time of recording, the running of the magnetic tape is controlled at a running speed of 1/7 of the normal speed.

Next, when the rotation of the reproducing head 1 is controlled at the same rotational speed as during recording and the magnetic tape is controlled to run at 1/7 the normal running speed, each of the reproducing heads disposed opposite to the reproducing head 1 is controlled. The recording tracks are alternately traced by the heads A and B, and the respective reproduction outputs are supplied to the mute switch 200 via the preamplifier 2. The mute switch 200 is controlled to be turned on by a switching pulse from a hexadecimal counter 180 described later. Therefore, only the video signal (the maximum-value video signal) reproduced in a completely on-track (just-track) state by each of the reproducing heads A and B is supplied to the subsequent video process processing system 3. I have.

The video signal supplied to the video processing system 3 is digitized by an A / D converter 230 and supplied to an equalizer 250 and a phase error detection circuit 240. The equalizer 250 performs a predetermined equalizing process on the video signal from the A / D converter 230, and supplies this to the demodulation circuit 270 (1 + D). The demodulation circuit 270 performs a demodulation process corresponding to a predetermined modulation process performed at the time of recording on the video signal from the equalizer 250, and subjects the video signal to ECC via a Viterbi decoding circuit 280.
Circuit 290. The ECC circuit 290 performs a predetermined error correction process on the video signal demodulated by the demodulation circuit 270, and supplies this to, for example, a monitor device via a D / A converter. As a result, an image corresponding to the video signal recorded and reproduced in the 7 × speed long play mode is displayed on the monitor device.

The PLL circuit 5 forms an operation clock to be supplied to each section 230, 250, 270, 290, etc. of the video processing system 3. Specifically, in the phase error detection circuit 240, the phase of the video signal from the A / D converter 230 and the voltage variable oscillator 260 (VC
The phase of the clock formed in O) is compared, a phase error detection output indicating the phase error between the two is formed, and this is supplied to the loop filter 220. Loop filter 220
Performs a predetermined filtering process on the phase error detection output with a predetermined time constant to form an error voltage corresponding to the phase error between the two. Variable voltage oscillator 260
The (VCO) forms a clock having a phase for canceling the phase error between the two based on the error voltage, and supplies the clock to the units 230, 250, 270, 290 and the like.

[Operation of Maximum Value Detection System 4] Next, the maximum value detection system 4 detects the timing of the video signal having the maximum value and controls the switching of the mute switch 200 as described below.

That is, when a video signal from the preamplifier 2 as shown in FIG. 2B is supplied to the envelope detection circuit 110, the envelope detection circuit 110 detects the envelope of this video signal, and The envelope detection output shown in FIG.

On the other hand, the edge detection circuit 125 is supplied with a DFF signal as shown in FIG. 2A which repeats a high level and a low level every time the reproducing head 1 makes a half turn. The edge detection circuit 125 detects the rising edge and the falling edge of the DFF signal, and supplies the edge detection output to the delay circuit 135 and the S / H circuit 130. The delay circuit 135 performs a delay process for the time described below on this edge detection output, thereby
A reset pulse as shown in (e) is formed and supplied to the integration circuit 120.

The integration circuit 120 integrates the envelope detection output from the envelope detection circuit 110 until the reset pulse is supplied from the delay circuit 135,
An integral output is formed as shown in FIG.
It is supplied to the H circuit 130. The S / H circuit 130 samples and holds the integrated output to form a sample / hold output as shown in FIG. 2 (f), and outputs the sample / hold output to the arithmetic circuit 155, the first delay circuit 140 and the second delay circuit. Circuit 1
50 respectively.

The timing of the integration process and the sample hold process will be described in more detail. The edge detection circuit 125 forms an edge detection output at the edge timing of the DFF signal shown in FIG.
This edge detection output is output from the delay circuit 135 as shown in FIG.
As shown in FIG. 3B, a delay process for one pulse of the edge detection output is performed and supplied to the integration circuit 120 as a reset pulse, and without being subjected to the delay process as shown in FIG. The signal is supplied as it is to the S / H circuit 130 as an S / H pulse.

That is, the S / H circuit 1 outputs the S / H circuit 1 pulse earlier than the reset pulse by one pulse of the edge detection output.
30. As a result, FIG.
The integration circuit 120 is reset immediately after sampling and holding the peak value of the integration output as shown in FIG.
The integrated output of the envelope detection output of the video signal during the half rotation of the reproducing head 1 can be accurately detected and sampled and held.

The envelope detection output has various shapes such as a pincushion shape, a drum shape, and a taper shape. In the magnetic reproducing apparatus of this embodiment, the envelope detection output for a predetermined period is integrated. Therefore, the difference in the shape of each envelope detection output can be absorbed (the shapes can be averaged), and the adverse effect of the difference in the shape of each envelope detection output on the reproduction operation can be reduced.

Next, the first delay circuit 140 delays the sample-and-hold output from the S / H circuit 130 for the time required for the reproducing head 1 to make a half turn (180 ° rotation = 1/60 sec). As a result, as shown in FIG. 2 (g), a sample-and-hold output which is delayed by one clock of the DFF signal is formed with respect to the sample-and-hold output output from the S / H circuit 130 as it is, and 14
Supply 0. In addition, the second delay circuit 150 has an S / H
By subjecting the sample and hold output from the circuit 130 to delay processing for the time required for the reproduction head 1 to make one rotation (360 ° rotation = 1/30 sec), as shown in FIG. The sample-and-hold output directly output from the circuit 130 is formed as a sample-and-hold output delayed by two clocks of the DFF signal.
40.

That is, the arithmetic circuit 155 uses the sample and hold output, which has been delayed by the first delay circuit 140 for half the rotation of the reproducing head 1, as a reference, and the sample which is about one clock of the DFF signal is used as a reference. Hold outputs will be supplied respectively. Arithmetic circuit 15
Reference numeral 5 denotes a current sample-and-hold output from the sample-and-hold output which has been subjected to the delay processing for the time required for the reproduction head 1 to make a half turn by the first delay circuit 140 serving as the reference, and a reproduction head by the second delay circuit 150. The arithmetic output as shown in FIG. 2 (i) is formed by subtracting the sample-and-hold output subjected to the delay processing for one rotation of one, and this is output to the non-inverting of the max-hold circuit 160 and the comparator 170. Supply to input terminal (+).

For example, as shown in FIGS. 2 (f) to 2 (h), the sample and hold output of the first delay circuit 140 serving as the reference, which has been subjected to the delay processing for the time required for the reproduction head 1 to make a half turn, is performed. The output level is “1”, the output level of the current sample hold output is “7”, and the second delay circuit 1
50, the output level of the sample-and-hold output subjected to the delay processing for one rotation of the reproducing head 1 is "5".
In this case, the arithmetic processing in the arithmetic circuit 155 forms an arithmetic output having an output level of "-11" shown in FIG. 2I (1-7-5 = -11). Hold circuit 160 and comparator 170
Is supplied to the non-inverting input terminal (+).

Similarly, as shown in FIGS. 2 (f) to 2 (h), the sample and hold output which has been subjected to the delay processing for the time for the reproduction head 1 to make a half rotation by the first delay circuit 140 serving as the reference. Is "7", the output level of the current sample hold output is "1", and the second delay circuit 1
50, the output level of the sample-and-hold output subjected to the delay process for one rotation of the reproducing head 1 is "1".
In this case, the arithmetic processing in the arithmetic circuit 155 forms an arithmetic output with an output level of "+5" shown in FIG. 2 (i) (7-1-1 = + 5), and this arithmetic output is used as the max hold circuit. 160 and the non-inverting input terminal (+) of the comparator 170.

Similarly, as shown in FIGS. 2 (f) to 2 (h), the sample and hold output which has been subjected to the delay processing for the time required for the reproduction head 1 to make a half rotation by the first delay circuit 140 serving as the reference. Is "5", the output level of the current sample hold output is "3", and the second delay circuit 1
50, the output level of the sample-and-hold output subjected to the delay process for one rotation of the reproducing head 1 is "1".
In this case, the arithmetic processing in the arithmetic circuit 155 forms an arithmetic output having an output level of "+1" shown in FIG. 2 (i) (5-3-1 = + 1). 160 and the non-inverting input terminal (+) of the comparator 170.

Next, the half circuit 165 outputs the maximum value hold output from the max hold circuit 160 to, for example, 1 /
By adjusting the level to a level of 2, a 1/2 maximum value hold output is formed and supplied to the inverting input terminal (-) of the comparator 170. For example, in this example, as shown by a dotted line in FIG.
Although the value of the maximum value hold output held by 0 is “5”, the 回路 circuit 165 reduces the value of “5” to の for the comparison process in the comparator 170 described below. By setting the value, a half-maximum value hold output of the value of “2.5” indicated by the solid line in FIG. 2I is formed and supplied to the inverting input terminal (−) of the comparator 170. Therefore, a half maximum value hold output of the value of “−2.5” appears at the inverting input terminal (−) of the comparator 170.

Next, the comparator 170 compares the inverted output value of the half maximum value hold output from the half circuit 165 with the arithmetic output value from the arithmetic circuit 155, and compares the comparison output with a hexadecimal counter. 180.

In this example, the inverted output value of the 1/2 maximum value hold output from the 1/2 circuit 165 is "-2.
5 ”, and if the operation output value from the operation circuit 155 is“ −11 ”, the inverted output value of the 最大 maximum value hold output is larger, so that the comparator 170
, The low-level comparison output as shown in FIG. 2 (j) is supplied to the hexadecimal counter 180.

Similarly, when the operation output value from the operation circuit 155 is "+5", the inverted output value of the 1/2 maximum value hold output is smaller, so that the comparator 170
, The high-level comparison output as shown in FIG. 2 (j) is supplied to the hexadecimal counter 180.

When the operation output value from the operation circuit 155 is "+1", the inverted output value of the 1/2 maximum value hold output is smaller, but in this case, the difference between them is "-2". .5 + 1 = -1.5 ", which is a very small difference. For this reason, this difference is absorbed as an error range of the comparator 170, and even when the inverted output value of the 1/2 maximum value hold output is smaller, the low-level comparison output is output as shown in FIG. It is supplied from 170 to a hexadecimal counter 180. Therefore, as in the case where the operation output value from the operation circuit 155 is “+5” (in this case, the difference between the two is −2.5 + 5).
= + 2.5), and the comparator 170 supplies a high-level comparison output to the hexadecimal counter 180 only when the difference between them is large to some extent.

Next, the hexadecimal counter 180 is shown in FIG.
When a high-level comparison output is supplied from the comparator 170 as shown in (2), the count value is reset by using this as a reset pulse as shown in FIG.
Start counting the FF signal. Then, a high-level switching pulse as shown in FIG. 2H is formed at the timing when the count value becomes “6”, and this is supplied to the mute switch 200. Mute switch 200
Is normally turned off, but is turned on when a high-level switching pulse is supplied from the hexadecimal counter 180 so that the video signal from the preamplifier 2 is supplied to the video processing system 3 at the subsequent stage. It has become.

The timing at which a high-level switching pulse is output from the hexadecimal counter 180 is determined by the video signal (the maximum-value video signal) reproduced by each of the reproducing heads A and B in a completely on-track (just-track) state. Is output from the preamplifier 2.
Therefore, in the video processing system 3 at the subsequent stage, the above-described video processing can be performed only on the video signal reproduced in the just-track state by the reproducing heads A and B.

That is, as shown in FIG. 2B, when the recording track is completely on-tracked and traced by one of the reproducing heads A and B, the reproduced output (video signal) is obtained.
Indicates the maximum value (maximum output period). During the period before and after this maximum output period, only one-seventh of the recording track is traced by one of the reproducing heads A and B corresponding to the azimuth angle. Because it is not done (Fig. 7 (b)
), The reproduction output before and after the maximum output period shows the lowest value (the minimum output period).

For this reason, when the arithmetic circuit 155 detects the difference between the sample-and-hold output during the maximum output period and the sample-and-hold output during the minimum output period before and after the maximum output period, the DFF signal of the DFF signal is counted from the timing of the maximum output period. An operation output having a value of “5” is obtained with a delay of the clock. The delay of one clock of the DFF signal is used to detect the difference between the reproduced output value during the maximum output period and the reproduced output value during the minimum output period before and after the maximum output period.
0, 150 is a delay caused by performing a delay process on each reproduction output.

From the timing of this maximum output period, the DFF
The operation output of the value "5" appearing one clock later of the signal becomes the maximum value including the operation outputs (+1, -5, -11, etc.) of other periods. This is for subtracting the sample and hold output of the minimum output period before and after the sample and hold output of the maximum output period. Comparator 1
70 detects this “5” period. As a result, as shown in FIG.
A reset pulse is supplied from the comparator 170 to the hexadecimal counter 180 with a delay of one clock of the FF signal.

The hexadecimal counter 180 outputs the DFF at the timing when the reset pulse is supplied as shown in FIG.
The count value of the signal is reset, and counting of the DFF signal is newly started.

In this example, the running of the magnetic tape is controlled at a running speed of 1/7 of the normal speed, and during the maximum output period, the recording track is traced in a just track state by one of the reproducing heads A and B. Appear when done.
For this reason, once the maximum output period appears, and then the maximum output period appears, the maximum output period appears only in the D period corresponding to the period next to the maximum output period.
This is the timing of the seventh DFF signal counted from the FF signal. However, as described above, the maximum output period is detected by the comparator 170 with a delay of one DFF signal clock from the timing of the maximum output period. Therefore, the next maximum output period appears at the timing when six DFF signals are counted after the detection of the maximum output period.

Therefore, the hexadecimal counter 180 is
As shown in (j) and (h), when the count value is reset by a reset pulse supplied one clock of the DFF signal from the timing of the maximum output period (count value 0), the DFF signal supplied after the reset is performed. Are counted (count values 1 to 6), and the mute switch 200 is turned on at the timing when the DFF signal is counted six times. As a result, as shown in FIGS. 2B and 2H, any one of the reproducing heads A,
The mute switch 200 can be turned on at the timing when the video signal (the maximum value video signal) reproduced in the state where B is a just track is output from the preamplifier 2, and only the maximum value video signal is output to the subsequent video process. It can be supplied to the processing system 3.

[Effects of the First Embodiment] As is clear from the above description, the magnetic reproducing apparatus according to the first embodiment of the present invention detects the envelope of the reproduction output and outputs the envelope detection output. The DFF signal is integrated for one clock period, and the integrated output is sampled and held to form a reproduced output for detecting the maximum value video signal in each period of one DFF signal clock. It has become. For this reason, even when the envelope detection output has various shapes such as a pincushion shape, a drum shape, and a taper shape, the difference in the shape of each envelope detection output can be absorbed by the integration processing (the shape is averaged). It is possible to accurately detect the reproduction output for each period. Accordingly, an accurate detection operation of the video signal having the maximum value can be performed.

Further, the magnetic reproducing apparatus according to the first embodiment has a reproduction output (first delay circuit 14) for a reference period.
0 sample-and-hold output) and subtracting the reproduction signal (the sample-and-hold output supplied from the sample-and-hold circuit 130 in real time and the sample-and-hold output of the second delay circuit 150) of the period before and after that from each other, , An operation output having a large level difference (operation output of the operation circuit 155) is formed, and the period of the video signal having the maximum value is detected based on the operation output. By the output, the video signal having the maximum value can be accurately detected from the video signals recorded and reproduced in the long play mode.

Further, in the magnetic reproducing apparatus according to the first embodiment, only the video signal having the maximum value can be supplied to the subsequent video processing system 3 and processed by the mute switch 200. The inconvenience of supplying the video signal of another period having a poor ratio to the video process system 3 can be prevented, and the malfunction of the magnetic reproducing device can be prevented.

<Second Embodiment> Next, a second embodiment of the present invention will be described.
The magnetic reproducing apparatus according to the embodiment will be described. The magnetic reproducing apparatus according to the second embodiment has a video processing system 3
As the loop filters provided in the PLL circuit 5, two loop filters having different time constants are provided, and both are switched according to the reproduction output value of the video signal. It should be noted that the above-described first embodiment differs from the second embodiment only in this point,
Hereinafter, only this difference will be described, and redundant description will be omitted.

[Structure of the Second Embodiment] That is, in the magnetic reproducing apparatus of the second embodiment, as shown in FIG. A first loop filter 191 having a large time constant and a second loop filter 191 having a small time constant for video signals other than the video signal having the maximum value.
And a changeover switch 210 for switching the output from each of the loop filters 191 and 192 according to the output from the hexadecimal counter 180 and supplying the output to the variable voltage oscillator 260.

In the magnetic reproducing apparatus according to the second embodiment, the mute switch 200 is omitted, and all reproduction outputs from the preamplifier 2 are supplied to the video processing system 3.

[Operation of Second Embodiment] In the magnetic reproducing apparatus of the second embodiment, the video signal from the preamplifier 2 is digitized by the A / D converter 230,
The video signal is subjected to the above-described video processing and output, and is also supplied to the phase error detection circuit 240. Note that, after the video data subjected to the video process processing, video signals other than the video signal having the maximum value are cut (muted) at a subsequent stage. Therefore, only the video signal of the maximum value is supplied to the monitor device or the like.

The phase error detection circuit 240 detects a phase error of the video data from the A / D converter 230, and supplies this phase error detection output to each of the loop filters 191 and 192. The first loop filter 191 performs a predetermined filtering process on the phase error detection output with a large time constant for the maximum value video signal, thereby forming an error voltage for the maximum value video signal, and switches the same. Supply to switch 210. Further, the second loop filter 192 performs a predetermined filtering process on the phase error detection output with a small time constant for video signals other than the video signal having the maximum value, so that , And supplies this to the changeover switch 210.

Here, the output from the hexadecimal counter 180 is output at the timing when the video signal having the maximum value is output from the preamplifier 2 as described with reference to FIGS. 2B and 2H. For this reason, the changeover switch 210
Until the output from the hexadecimal counter 180 is supplied, an error voltage for a video signal other than the video signal having the maximum value formed by the second loop filter 192 is selected and a voltage variable oscillator is selected. 260 and the hexadecimal counter 1
At the timing when the output from 80 is supplied, the maximum error voltage for the video signal formed by the first loop filter 191 is selected and supplied to the voltage variable oscillator 260.

Thus, the clock having the phase for canceling the phase error of each video signal is supplied to the voltage variable oscillator 260.
(VCO) can drive the video processing system 3 and enable video processing to be performed on video signals in each period at accurate timing.

[Effects of the Second Embodiment] As described with reference to FIG. 2B, the period before and after the period during which the video signal having the maximum value is reproduced (the maximum output period) is the minimum value. This is a period during which the video signal is reproduced (minimum output period). When the minimum output period is reached, the value of the video signal decreases.
Although the response of the L circuit 5 becomes unstable, the magnetic reproducing apparatus according to the second embodiment has an error for the maximum value video signal formed by the loop filters 191 and 192 having different time constants. Since the voltage and the error voltage for the video signal other than the maximum value video signal are switched and supplied to the voltage variable oscillator 260, the response of the PLL circuit 5 can be stabilized even in the minimum output period. it can. For this reason, the video processing system 3 can be driven by a stable clock regardless of the reproduction level of the video signal, and the video signal of each period can be subjected to the video processing at an accurate timing. The same effect as in the first embodiment can be obtained.

<Third Embodiment> Next, a third embodiment of the present invention will be described.
The magnetic reproducing apparatus according to the embodiment will be described. The magnetic reproducing apparatus according to the third embodiment includes the mute switch 200 described in the first embodiment and the first and second loop filters 19 described in the second embodiment.
1 and 192 are provided together. It should be noted that each of the above-described embodiments is different from the third embodiment only in this point, and therefore only the difference will be described below, and redundant description will be omitted.

[Structure of Third Embodiment] That is, in the magnetic reproducing apparatus of the third embodiment, a mute switch 200 is provided between a preamplifier and an A / D converter 230 as shown in FIG. The first and second loop filters 19 are provided after the phase error detection circuit 240 of the PLL circuit 5.
1, 192 and a switch 210 for switching the output of each loop filter 191, 192. As described below, in the magnetic reproducing apparatus according to the third embodiment, only the video signal having the maximum value is supplied to the video process processing system 3. For this reason, the time constant of the first loop filter 191 is a large time constant for the maximum value video signal, and the second loop filter 192 is a small time constant for the time when the video signal is not supplied. Has become.

[Operation of Third Embodiment] The magnetic reproducing apparatus of the third embodiment has the structure shown in FIGS. 2B and 2H.
As described above, the output from the hexadecimal counter 180 is output at the timing when the video signal having the maximum value is output from the preamplifier 2, and is supplied to the mute switch 200 and the changeover switch 210, respectively. As a result, only the video signal having the maximum value is supplied to the video processing system 3 at the subsequent stage. Video processing system 3
Performs the above-described video processing on the video signal having the maximum value, and supplies the video signal to a monitor device or the like. This allows
An image corresponding to the image signal recorded in the 7 × speed long play mode can be displayed on a monitor device or the like.

On the other hand, the PLL circuit 5 detects the phase error between the phase of the video signal having the maximum value and the phase of the clock formed by the variable voltage oscillator 260 by the phase error detection circuit 240, and The detection output is supplied to first and second loop filters 191 and 192, respectively. As described above, the first loop filter 191 has a large time constant for the maximum-value video signal. With this large time constant, a predetermined filtering process is performed on the phase error detection output of the maximum-value video signal. By applying this, an error voltage for the video signal having the maximum value is formed, and this is changed by the changeover switch 210
To supply.

The changeover switch 210 is provided as shown in FIG.
As described with reference to (h), based on the output from the hexadecimal counter 180 supplied at the timing when the maximum value video signal is output from the preamplifier 2, the error voltage for the maximum value video signal is calculated. And supplies it to the variable voltage oscillator 260. This makes it possible to perform video process processing on the maximum value video signal at an accurate timing.

Here, in the magnetic reproducing apparatus of the third embodiment, only the video signal of the maximum value is supplied to the video processing system 3, and during the other periods, the video processing is performed. Since no video signal is supplied to the system 3, the PLL circuit 5, which requires a phase error detection output for servo lock, starts pulling in the phase after the video signal of the maximum value is supplied and responds. May be delayed.

For this reason, the magnetic reproducing apparatus according to the third embodiment has a small time constant during a period (no signal period) other than the period during which the video signal of the maximum value is supplied to the video processing system 3. The second loop filter 192 forms an error voltage. Then, the changeover switch 210 selects the error voltage formed by the second loop filter 192 and supplies it to the variable voltage oscillator 260.

As a result, even in the non-signal period, the PLL
Since the circuit 5 can always be operated, the PLL
The circuit 5 can pull in the phase with good responsiveness at the timing when the video signal of the maximum value is supplied, and can form a clock with an accurate phase in the variable voltage oscillator 260.

[Effects of the Third Embodiment] As is clear from the above description, the magnetic reproducing apparatus of the third embodiment of the present invention selects only the video signal having the maximum value and performs the video process processing. Clocks for video processing can be provided with first and second clocks having different time constants.
Are formed in accordance with the error voltages formed by the loop filters 191 and 192 of the above, so that the video process processing system 3 can be driven at an accurate timing to perform video process processing on the video signal having the maximum value. The same effects as in the above embodiments can be obtained.

[Modification of the Present Invention] Finally, in the description of each of the above embodiments, the maximum value detection system 4 is realized by hardware, but this is realized by, for example, a DSP (Digital Signal Processor). It may be realized by software control.

In the above embodiment, only the reproduced video signal has been described. However, when an audio signal is recorded together with the video signal on the magnetic tape, the audio signal is also transmitted together with the video signal in the above-described configuration. It goes without saying that it is processed in

In addition, the present invention is not limited to each of the above-described embodiments described as examples, and a range other than the above-described embodiments does not depart from the technical idea of the present invention. Of course, various changes are possible according to the design and the like.

[0097]

According to the magnetic reproducing apparatus of the present invention, the envelope is detected every time the rotary drum makes a half turn, and the envelope detection output is integrated to perform integration. The information level corresponding to the reproduction head trace is obtained as an output. Accordingly, even when the envelope detection output has various shapes such as a pincushion shape, a drum shape, and a taper shape, the difference in the shape of each envelope detection output can be absorbed by the integration process (the shape is averaged). And it is possible to detect an accurate information level for each trace.
Therefore, the control means can accurately detect the timing at which a predetermined value of reproduction information is supplied from each reproduction head to the signal processing means.

In addition, of the integrated outputs sequentially supplied from the integrating means, successive three integrated outputs are sequentially added / subtracted to form an information level corresponding to each trace. Detection of the maximum information level by the means can be facilitated.

Further, the control means supplies reproduction information from each of the reproduction heads to the signal processing means with reference to the timing at which the maximum output is detected from the continuous n integrated outputs. Further, by controlling the supply / non-supply control means, it is possible to accurately supply only the reproduction information of a predetermined value to the signal processing means among the reproduction information reproduced by the respective reproduction heads. For this reason, S /
Reproduced information having a poor N ratio is supplied to the signal processing means, thereby preventing an inconvenience of malfunction.

Further, in the magnetic reproducing apparatus according to the present invention, at the timing at which the reproduction information of the maximum level is reproduced by each reproduction head, the phase based on the first response characteristic for the reproduction information of the maximum level is obtained. The signal processing means is driven by the clock generated by the error signal, and when reproduction information other than the maximum level reproduction information is reproduced, a second response characteristic for the reproduction information other than the maximum level reproduction information. And the signal processing means is driven by the clock generated by the phase error signal. Thus, it is possible to perform signal processing with a stable clock without being affected by the level of the reproduction information.

In the magnetic reproducing apparatus according to the third aspect of the present invention, the supply / non-supply control means supplies only the maximum level reproduction information to the signal processing means for signal processing, and the maximum level reproduction information. A block based on the phase error signal obtained by switching between the first response characteristic for the reproduction and the second clock for the reproduction information other than the reproduction information of the maximum level is supplied to the signal processing means. As a result, only the maximum level of reproduction information can be signal-processed with a stable phase synchronization signal.

[Brief description of the drawings]

FIG. 1 is a block diagram of a magnetic reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a time chart showing signal outputs of respective units of the magnetic reproducing apparatus according to the first embodiment.

FIG. 3 is a time chart for explaining timings of an integration process and a sample hold process performed on a reproduction output of the magnetic reproducing device according to the first embodiment.

FIG. 4 is a block diagram of a magnetic reproducing apparatus according to a second embodiment of the present invention.

FIG. 5 is a block diagram of a magnetic reproducing apparatus according to a third embodiment of the present invention.

FIG. 6 is a diagram for explaining a rotary head provided in a conventional magnetic recording / reproducing apparatus of the D-VHS system.

FIG. 7 illustrates a conventional magnetic recording / reproducing device 7 of the D-VHS system.
5 is a time chart for explaining recording timing and reproduction timing of an information signal in a double speed long play mode.

FIG. 8 is a schematic diagram showing recording tracks of information signals recorded on a magnetic tape by a conventional magnetic recording / reproducing apparatus of the D-VHS system.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 playback head 2 preamplifier 3 information data playback processing system 4 maximum value detection system 5 PLL circuit 110
Envelope detection circuit, 120: integration circuit, 125: edge detection circuit, 130: sample and hold circuit, 135
... delay circuit, 140 ... first delay circuit, 150 ... second delay circuit, 155 ... arithmetic circuit, 160 ... max hold circuit, 165 ... 1/2 circuit, 170 ... comparator,
180 hexadecimal counter, 191 first loop filter, 192 second loop filter, 200 mute switch, 220 loop filter, 230 A / D converter, 240 phase error detection circuit, 250 equalizer , 260 ... variable voltage oscillator, 270 ... demodulation circuit, 2
80: Viterbi decoding circuit, 290: Error correction circuit

Claims (3)

[Claims] 1. A tape-shaped magnetic recording medium which is 1 / n of a normal
And at least two recording heads provided on the rotating drum and having different azimuth angles, the adjacent recording tracks have different azimuth angles at a rate of once every time the rotating drum rotates n / 2 times. (N is an odd number of 3 or more) for reproducing information obliquely magnetically recorded on a magnetic recording medium such that
Traveling control means for controlling traveling at a traveling speed of: at least two reproducing heads provided on the rotating drum, each having an azimuth angle corresponding to the azimuth angle of each of the recording heads; and a rotation provided with each of the reproducing heads. Rotation control means for controlling the rotation of the drum at the same rotation speed as at the time of recording the information; signal processing means for performing predetermined signal processing on the reproduction information reproduced by each of the reproduction heads; Supply / non-supply control means for controlling supply / non-supply of reproduction information supplied to the signal processing means; envelope detection means for detecting an envelope of reproduction information reproduced by each of the reproduction heads; and envelope detection means. An integrating means for performing an integration process for each envelope detection output of, among the integrated outputs sequentially supplied from the integrating means, Three consecutive integrated outputs are sequentially added / subtracted to obtain a continuous n
Control means for detecting a timing at which the output becomes maximum among the integrated outputs, and controlling supply / non-supply of the reproduction information in the supply / non-supply control means with reference to the timing at which the output is maximum; A magnetic reproducing device comprising: 2. A tape-shaped magnetic recording medium having a 1 / n
And at least two recording heads provided on the rotating drum and having different azimuth angles, the adjacent recording tracks have different azimuth angles at a rate of once every time the rotating drum rotates n / 2 times. (N is an odd number of 3 or more) for reproducing information obliquely magnetically recorded on a magnetic recording medium such that
Traveling control means for controlling traveling at a traveling speed of: at least two reproducing heads provided on the rotating drum, each having an azimuth angle corresponding to the azimuth angle of each of the recording heads; and a rotation provided with each of the reproducing heads. Rotation control means for controlling the rotation of the drum at the same rotation speed as when recording the information; signal processing means for performing predetermined signal processing on the reproduction information reproduced by the reproduction heads; and reproduction by the reproduction heads Envelope detection means for detecting the envelope of the reproduced information obtained, integration means for performing integration processing for each envelope detection output from the envelope detection means, and three continuous outputs among the integration outputs sequentially supplied from the integration means. The integration output is sequentially added / subtracted to obtain a continuous n
Timing detection means for detecting a timing at which the output becomes maximum among the integrated outputs; clock generation means for supplying a clock having a frequency corresponding to an input signal to the signal processing means; and a clock from the clock generation means. Phase error output means for inputting a phase error signal indicating a phase error between the data and the reproduction information reproduced by each of the reproduction heads to the clock generation means with first or second response characteristics, and detection by the timing detection means And a response characteristic switching means for switching between the first response characteristic and the second response characteristic in the phase error output means with reference to the timing at which the output becomes maximum. 3. A tape-shaped magnetic recording medium is set to 1 / n of a normal
And at least two recording heads provided on the rotating drum and having different azimuth angles, the adjacent recording tracks have different azimuth angles at a rate of once every time the rotating drum rotates n / 2 times. (N is an odd number of 3 or more) for reproducing information obliquely magnetically recorded on a magnetic recording medium such that
Traveling control means for controlling traveling at a traveling speed of: at least two reproducing heads provided on the rotating drum, each having an azimuth angle corresponding to the azimuth angle of each of the recording heads; and a rotation provided with each of the reproducing heads. Rotation control means for controlling the rotation of the drum at the same rotation speed as at the time of recording the information; signal processing means for performing predetermined signal processing on the reproduction information reproduced by each of the reproduction heads; Supply / non-supply control means for controlling supply / non-supply of reproduction information supplied to the signal processing means; envelope detection means for detecting an envelope of the reproduction information reproduced by each of the reproduction heads; An integrating means for performing an integration process for each envelope detection output of, among the integrated outputs sequentially supplied from the integrating means, Three consecutive integrated outputs are sequentially added / subtracted to obtain a continuous n
Timing detection means for detecting a timing at which the output becomes maximum among the integrated outputs; clock generation means for supplying a clock having a frequency corresponding to an input signal to the signal processing means; and a clock from the clock generation means. Phase error output means for inputting a phase error signal indicating a phase error between the data and the reproduction information reproduced by each of the reproduction heads to the clock generation means with first or second response characteristics, and detection by the timing detection means The supply / non-supply of the reproduction information is controlled by the supply / non-supply control means based on the timing at which the output is maximized, and the first response characteristic and the second response characteristic of the phase error output means are controlled. And a control means for switching between and.