JPH0752536B2 - Rotating head type magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type magnetic recording / reproducing apparatus having a rotary head, and more particularly to a video tape recorder and a PC.
The present invention relates to a recording / reproducing device suitable for tracking control of an M recorder.

[Background of the Invention]

The rotary head type magnetic recording / reproducing apparatus is widely used as a consumer device such as a video tape recorder and an audio PCM recorder. The rotary head type magnetic recording / reproducing apparatus forms and records an oblique track on a magnetic tape as a recording medium. Further, in order to increase the recording density, no guard band is provided between the adjacent tracks, and crosstalk from the adjacent tracks during reproduction is reduced by causing the azimuth angle of the recording / reproducing head to be different between the adjacent tracks and by azimuth loss. .

In such a rotary head type magnetic recording / reproducing apparatus, the reproducing head needs to accurately trace the track recorded on the magnetic tape, and the tracking control for controlling it plays an important role.

Conventionally, tracking control of a video tape recorder is performed by using a dedicated track for recording a control signal for control. This method does not interfere with the image signal, which is the main signal, but it requires a dedicated area on the tracking control head and magnetic tape, and is different from the track on which the main signal is actually recorded. However, there is a hardware and performance defect that the performance is not suitable for high density recording and reproduction.

In order to improve this, as a conventional method that does not require a recording track of control signals, the pilot signals are spatially arranged as in Japanese Patent Publication No. 56-20621 and Japanese Patent Publication No. 54-3507. There is a system in which a main signal is frequency-multiplexed and recorded, and a tracking error signal is obtained by using a crosstalk amount of a pilot signal from an adjacent track during reproduction. However, in this method, since the pilot signal is recorded on the PCM signal or the image signal which is the main signal by frequency multiplexing, there is essentially interference that the pilot signal gives to the main signal, and in order to reduce the effect, the pilot signal There is no choice but to lower the recording level to the level of the main signal.
For this reason, the S / N of the reproduced pilot signal becomes insufficient and stable tracking control cannot be performed.

Further, when recording / reproducing with two rotary magnetic heads A and B having different azimuth angles, in the method of the above literature, the spatial arrangement pattern of the pilot signal recorded by the A head and the spatial arrangement pattern recorded by the B head are Since they are the same, even when the track recorded by the A head is reproduced by the B head, it becomes a stable point of tracking control, and the main signal is not reproduced. Therefore, such a track identification function is not provided in the pilot signal itself, and there is a drawback that it is necessary to provide another means.

[Object of the Invention]

An object of the present invention is to reduce the area on the magnetic tape where the pilot signal for tracking control is recorded, without interfering with the PCM digital signal or the image signal which is the main signal,
It is an object of the present invention to provide a rotary head type magnetic recording / reproducing apparatus capable of discriminating tracks during 2-head azimuth recording / reproducing.

[Outline of Invention]

In the rotary head type magnetic recording / reproducing apparatus according to the present invention, the recording track area is divided into an area in which a main signal of a PCM signal or an image signal is recorded and an area in which a control signal for tracking control is recorded to prevent mutual interference. The track control area is reduced and the track identification is performed by using the pilot signals of the frequencies ₁ and _{2 which} have no effect of azimuth loss for each track as the control signal for the tracking control. It is in.

Example of Invention

Hereinafter, as one embodiment of the present invention, 2 having different azimuth angles will be described.
A PCM recorder using one rotating magnetic head will be described.

FIG. 1 shows a block diagram of the PCM recorder of the present invention. The rotary magnetic heads 1 and 2 for recording / reproducing are rotary transformers, and the signal of the rotary magnetic head 1 corresponds to the signal line 6 and the signal of the rotary magnetic head 2 corresponds to the signal line 7. 16 is a motor for rotating the rotary magnetic heads 1 and 2, 17 is a rotation speed detector for detecting the rotation speed of the motor, and 20 is an output of the rotation speed detector 17 to obtain a signal of a frequency corresponding to the rotation speed. To be 18 is a rotation speed control circuit of the motor 16, and 19 is an output of the rotation speed control circuit 18 to drive the motor 16. 4 is a magnetic tape of the recording medium 5
Is a recording track to be recorded on the magnetic tape 4, 21 is a motor for feeding the magnetic tape, 22 is a rotation speed detector of the motor 21, 23 is an output of the rotation speed detector 22, and 25 is a motor 21.
The rotation speed control circuit, 24 drives the motor 21 by the output of the rotation speed control circuit 25. 8 and 9 are switches for switching between recording and reproduction, and recording is performed on the 8R and 9R sides and reproduction is performed on the 8P and 9P sides. 15L and 15R are analog signal input terminals, 14A is an A / D converter for converting an analog signal into a digital signal, 14B is a recording system signal processing circuit for apologizing detection / correction code, adding a sync signal, etc., 12 and 13
Is for tracking control and has no effect on azimuth loss 2
Oscillators that generate pilot signals of frequencies ₁ and ₂ , 10 and 1
1 is a switch for switching, and 9A is a recording amplifier. 26 and 27 are reproduction amplifiers, 28 is a changeover switch, 29 is a tracking control circuit, 30 is a waveform equalization circuit, 31 is a comparator for discriminating "1" or "0" of data, and 32A is an error of a reproduced digital signal. A reproduction system signal processing circuit for performing processing such as detection and correction,
32B is a D / A converter that converts a digital signal into an analog signal, and 33L and 33R are analog signal output terminals. Also, 34
Is a clock generation circuit that supplies the clock to each part.
Reference numerals 5 and 38 are reference clocks for the reproduction and recording signal processing circuits 32A and 14B, and 36 is a clock having a duty ratio of 50% that is the same frequency as the rotation frequency of the motor 16, and the rotation speed control circuits 18 and 2 are provided.
5, in addition to the tracking control circuit 29, the switch 28,
Control 11 37 is a clock for controlling the switch 10,
Switches 10, 11, 28 are 10 when the control clock is at "1" level.
When “0” level is set on A, 11A, 28A side, 10B, 11B, 28B side is selected.

The operation of FIG. 1 during recording will be described with reference to the timing chart of FIG. The numbers on the left side of FIG. 2 correspond to the reference numerals of the respective parts of FIG.

Left and right 2 channel analog signals are input terminals 15L, 15R
In addition, the signal is converted into a digital signal by the A / D converter 14A and added to the recording system signal processing circuit 14B. Recording system signal processing circuit 14B
Then, based on the clock 38 generated by the clock generation circuit 34, a code for error detection and correction is added to the digital signal, interleaved, and a synchronization signal is added. The recording system signal processing circuit 14B further stores these data in a RAM (writeable / readable memory), and intermittently synchronizes with the clock 36 of the clock generation circuit 34 as shown in FIGS.
Output M data. On the other hand, the oscillators 12 and 13 that generate the pilot signals for tracking control are shown in FIG.
As shown in 0A, frequency _{1, 2} appear alternately in synchronism with the clock 36 by the switch 11. In the switch 10, switching is controlled by the clock 37 of the clock generation circuit 34 in order to add the pilot signal 10A before and after the intermittent PCM data 10B, and the signal shown in FIG. 2 is obtained. This signal is a recording amplifier
9A, rotary magnetic heads 1 and 2 for recording and reproduction via switches 8 and 9
And is recorded on the magnetic tape 4. At this time the motor
The rotation speed detector 17 and the rotation speed control circuit 18 control 16 so that the output 20 of the rotation speed detector 17 and the clock 36 are in phase with each other so that the rotation speed is the same as the frequency of the clock 36. Therefore, as shown in FIG. 2, the rotary magnetic heads 1 and 2 perform recording while the head 1 contacts the magnetic tape 4 when the clock 36 is at "1" level, and the head 2 when the clock 36 is at "0" level. Makes contact with the magnetic tape 4 to perform recording.
Further, the magnetic tape 4 is sequentially fed by a tape feeding motor 21, and a recording track 5 is formed on the magnetic tape 4. The shape of the recording track 5 thus recorded on the tape is shown in FIG. In FIG. 3, T _P is the track pitch, Hw is the head width of the rotary magnetic heads 1 and 2, θ is the track angle from the tape edge, and α is the deviation between adjacent tracks caused by forming an oblique track. The length is α = TP / tan θ. When the rotating magnetic head 1 contacts the magnetic tape 4, first, the pilot signal frequency
After recording ₁ , write PCM data, and finally write ₁ again.
Is recorded to form a track. Next, when the rotary magnetic head 2 contacts the magnetic tape 4, the pilot signal frequency ₂ is recorded, PCM data is written, ₂ is recorded again, and another track is formed. Therefore, as shown in FIG. 3, the pilot signal is written from the tape edge, and the frequency changes from ₁ to ₂ for each track.

The track shape shown in FIG. 3 was obtained by the above operation of the recording system. The operation of the reproducing system for properly tracing this track and reproducing the signal will be described below.

In FIG. 1, the switches 8 and 9 are connected to the 8P and 9P sides during reproduction, and the signal from the rotary magnetic head 1 is sent to the playback amplifier 27 and the rotary magnetic head 2
Signal is added to the reproduction amplifier 26. Rotating magnetic head 1,2
Is rotated by the motor 16 at the same frequency as the clock 36 as during recording. Therefore, a reproduction signal appears in the reproduction amplifiers 26 and 27 only while the rotary magnetic heads 1 and 2 are alternately in contact with the magnetic tape 4. The switch 28 switches the alternately reproduced signals by the clock 36 to form one reproduced signal. The output of the switch 28 is applied to the waveform equalization circuit 30 and the tracking control circuit 29. The reproduced signal, which has been compensated for the phase amplitude on the transmission line by the waveform equalizing circuit 30, is shaped into a digital signal by the comparator 31, and is added to the reproducing system signal processing circuit 32A. The reproduction system signal processing circuit 32A takes in the input digital signal, deinterleaves it, detects an error,
The data is corrected and added to the D / A converter 32B, and an analog signal is output to the output terminals 33L and 33R. Thus, in order to obtain the reproduction signal, the rotary magnetic heads 1 and 2 must properly trace the track, and the tracking control circuit 29 works to control it. The output signal of the switch 28 is added to the tracking control circuit 29, and the tracking error signal is detected by using the signals of pilot signal frequencies ₁ and ₂ . The tracking error signal is the rotation speed control circuit 25
In addition, by changing the number of rotations of the motor 21 in accordance with the tracking error signal, the feeding speed of the magnetic tape 4 is changed so that the tracking error does not occur.

Hereinafter, the tracking control circuit 29 will be described in detail. FIG. 4 shows a configuration diagram of the tracking control circuit 29, and FIG. 5 shows a timing chart of each part in FIG. In Figure 4
40 is an input terminal for the signal from the switch 28 in FIG.
42 is a band pass filter of frequency ₂ and ₁ , 43 and 44
Is an envelope detection circuit that detects the envelope of the signal, 45 and 46 are switches controlled by the clock of the input terminal 56, 47 is a clipper circuit, 48 is a 2-bit shift register, and 481Q and 481 are the first bits of the shift register 48. , 482Q, 482 is the positive / negative output of the second bit of the shift register 48, 50 and 51 are AND circuits, 49 is the clock input terminal of the register 48, 56 is the input terminal of the clock 36 in FIG.
52 and 53 are sample hold circuits, 54 is an analog subtraction circuit, and 55 is an output terminal of a tracking error signal. Further, the symbols attached to the left side of FIG. 5 correspond to the symbols of the respective parts of the circuit of FIG. 4 and represent the output signals of the respective circuits. The circuit operation of FIG. 4 will be described below. The signal applied to the input terminal 40 of FIG. 4 is first adjacent to the left side because the pilot signal frequencies ₁ and ₂ have no azimuth loss when the rotary magnetic head 1 comes into contact with the magnetic tape 4 due to the recording track shape of FIG. Pilot signal ₂ from the truck is detected as crosstalk, then the pilot signal of the home truck
₁ appears, and then the pilot signal ₂ from the right adjacent track is detected as crosstalk. After detecting the PCM data, the rotary magnetic head 1 again detects the pilot signal ₂ from the left adjacent track and the pilot signal _{2 from} the right adjacent track as ₂ as crosstalk.
After the rotary magnetic head 1 traces, the rotary magnetic head 2
Detects a signal similarly to the rotary magnetic head 1, but the crosstalk of the pilot signal from the adjacent track is ₁ . Therefore, the outputs of the band pass filters 41 and 42 in FIG. 4 are from the adjacent tracks before and after the output of 42 which is the output of the pilot signal frequency _{1 in} the reproduction of the rotary magnetic head 1 as shown in FIGS. The output 41 of the pilot signal frequency ₂ appears due to crosstalk. In reproducing the rotary magnetic head 2, the pilot signal frequency ₂ output 41
Before and after, the output 42 of the pilot signal frequency ₁ appears due to the crosstalk from the adjacent tracks. As shown in FIG. 3, when the rotary magnetic head 1 shifts toward the left adjacent track, the level of the first half is high and the level of the second half is low. On the contrary, when the track shifts to the right adjacent track, the level of the first half is low and the level of the second half is high. Bandpass filter 41,4
The output of 2 is added to the envelope detection circuits 43 and 44, and is shown in FIG.
The waveform is shown by 43,44. The outputs of the envelope detection circuits 43 and 44 are switched by the clock applied to the clock input terminal 56 by the switches 45 and 46 as shown in FIG. As shown in FIG. 5, the output of the switch 45 selects the output of the envelope detection circuit 43 when the clock input terminal 56 is at "1" level, and selects the output of the envelope detection circuit 44 when it is at "0" level.
Select the output of. Therefore, the output of the switch 45 is the envelope of the pilot signal obtained by the crosstalk from the adjacent tracks. Since the switch 46 is the reverse of the selection of the switch 45, the envelope of the pilot signal of the home track is obtained, and when added to the clipper circuit 47, the waveform of FIG. Clipper circuit 47
The output of is added as data in shift register 48.
A clock having a higher frequency than the output pulse of the clipper circuit 47 is applied to the clock input terminal 49 of the shift register 48,
The rising edge detection signal of the output pulse of the clipper circuit 47 is output to the output of the AND circuit 50. Further, the AND circuit 51 outputs the falling edge detection signal of the output pulse of the clipper circuit 47. The pulse outputs of the AND circuits 50 and 51 are added as sample and hold pulses of the sample and hold circuits 53 and 52, and the output signal of the switch 45 is set at each timing.
Hold on. This timing is shown in FIGS. 45, 50 and 51 in FIG. 5, and the sample and hold circuit 53, which samples and holds with the output pulse of the AND circuit 50, shows that the first half of the crosstalk pilot signal from the adjacent track, that is, the rotary heads 1 and 2 Hold the level corresponding to the amount of shift to the left adjacent track. The sample-hold circuit 52 that samples and holds with the output pulse of the AND circuit 51 has a level corresponding to the second half of the crosstalk pilot signal from the adjacent track, that is, the amount by which the rotary heads 1 and 2 deviate to the right adjacent track. Hold on. Therefore, in the analog operation circuit 54, as shown in FIG.
Tracking error signal output 55, subtracting the output of 2,53
Is a signal indicating how much the rotary magnetic heads 1 and 2 are displaced in the adjacent track direction to the right when the voltage is positive and to the left when the voltage is negative. By controlling the number of rotations of the tape feeding motor 21 shown in FIG. 1 using the tracking error signal 55, the rotary magnetic heads 1 and 2 can be correctly traced on the track.

FIG. 6 shows a block diagram of the tracking control circuit of the present invention for detecting the levels ₁ and _{2 by} the converter method. In FIG. 6, 60 and 61 are local oscillators, 62 is a multiplication circuit for frequency conversion, 63 and 64 are bandpass filters of a and 2a frequencies, respectively, and other symbols are the same as those in FIG. Has the same function. It is assumed that the pilot signal frequencies ₁ and ₂ have a relationship of ₁ > ₂ . Frequency of local oscillator 60 ₁ l and frequency of local oscillator 61
₂ The value of l, as shown in FIG. 7 ₁ l ₌ 2 1 _- 2 =
_{1 + a, 2 l = 2} 2 - a _{1 =} 2 -a. When the signal applied to the input terminal 40 has a pilot frequency of _{1 on} the home track and a pilot frequency of ₂ due to crosstalk from an adjacent track, the local oscillator 60 with the switch 45
Is selected and the frequency ₁ l is added to the multiplication circuit 62. Therefore, the pilot signal frequency ₁ of the home truck is ( ₁ l-
₁ ) = a and appears in the output of the bandpass filter 63, and the pilot signal frequency ₂ due to crosstalk becomes ( ₁ l− ₂ ) 2a and the bandpass filter 64
Appears in the output of. The home truck has a pilot frequency of ₂ and the crosstalk has a pilot frequency of _1.
, The local oscillator 61 is selected by the switch 45, and the frequency
₂ l is added to the multiplication circuit 62. Therefore, the pilot signal frequency _second home track, _{(2 l-2)} = a, and the pilot signal frequency ₁ by crosstalk becomes _{(2 l-1)} = 2a, the band-pass filter
Appears at 63 and 64 respectively. That is, the local oscillator 60,
By switching 61, the level of the pilot signal of the home track appears in the bandpass filter 63, and the level of the pilot signal due to crosstalk from the adjacent track appears in the bandpass filter 64. Therefore, as in FIG. 4, these levels can be detected and a tracking error signal can be obtained.

The above tracking control circuit operates by detecting the crosstalk pilot signal level from the left adjacent track at the rising edge of the home track pilot signal and crossing from the right adjacent track at the falling edge of the home track pilot signal level. The talk pilot signal level will be detected. Therefore, if there is a section of α or more as shown in FIG. 3 as the area for recording the pilot signal, the pilot signal level of the crosstalk from the left and right adjacent tracks can be detected regardless of the size of the recording area, and the storage area is It can be small. Track identification when recording / reproducing with two rotary magnetic heads having different azimuth angles is carried out by the rotary magnetic head 1 recording a pilot signal frequency ₁ at the time of recording, as is apparent from FIGS. 2 and 3 of the above embodiment. The rotary magnetic head 2 records the pilot signal frequency _2, and the head tracing the pilot signal frequency ₁ from FIG. 5 at the time of reproduction is the rotary magnetic head 1 and the head tracing the pilot signal frequency ₂ is the rotary magnetic head 2. Operate. Therefore, track identification is possible and stable tracking control can be performed.

The rotary head type magnetic recording / reproducing apparatus for recording / reproducing a PCM digital signal has been described in the embodiment of the present invention, but in the case of recording / reproducing an image signal, the A / D converter 14 of FIG.
A, the recording system signal processing circuit 14B becomes the video signal modulation circuit, the waveform equalization circuit 30, the comparator 31, the reproduction system signal processing circuit 32A, the D / A converter 32B becomes the car video signal demodulation circuit. Obviously, the same operation is performed as in the case of signals.

Further, in the embodiment of the present invention, the pilot signal is inserted at the beginning and the end of the track, but by controlling the output timing of the recording system signal processing circuit 14B and the switching timing of the switch 10, a plurality of pilot signals are provided on the track. It is possible to insert it, and it is apparent that the tracking control circuit shown in FIG. 4 operates in this case as well.

〔The invention's effect〕

According to the present invention, the track area is divided into an area for recording a main signal of PCM data and an image signal and an area for recording a pilot signal for detecting a tracking error, and the frequency of the pilot signal is azimuth. By alternating the two frequencies, which have no loss effect, for each track, the recording area of the pilot signal can be narrowed, the main signal is not disturbed, track identification is possible, and stable tracking control is performed. There is an effect that it can be used as a rotary head type magnetic recording / reproducing apparatus.

[Brief description of drawings]

FIG. 1 is a block diagram of a rotary head type magnetic recording / reproducing apparatus of the present invention, FIG. 2 is a timing chart at the time of recording of the rotary head type magnetic recording / reproducing apparatus of the present invention, and FIG. 3 is a rotary head type of the present invention. FIG. 4 is a diagram showing a signal shape of a magnetic tape recorded by a magnetic recording / reproducing apparatus, FIG. 4 is a diagram showing a configuration of the tracking control circuit 29 of FIG. 1, and FIG. 5 is a diagram showing signals of respective parts of FIG. FIG. 6 is a timing diagram for omitting, FIG. 6 is a configuration diagram of the first tracking control circuit 29 by the conversion method, and FIG. 7 is a diagram showing spectra of the local oscillators 60 and 61 of FIG. 1,2 …… Rotary magnetic head, 16,21 …… Motor, 18,25 …… Motor speed control circuit, 12,13 …… Pilot signal oscillator, 29 …… Tracking control circuit, 41,42 …… Band pass , Filter, 43,44 Envelope detection circuit, 47 …… Clipper circuit, 52,53 …… Sample hold circuit, 60,61 …… Local oscillator, 62 …… Multiplier circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Furihata Takashi Furihata 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Home Appliance Research Institute, Hitachi, Ltd. (72) Inventor Fujio Okamura 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Inside the Hitachi Home Appliances Research Laboratory (72) Inventor Akira Terada 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Inside the Hitachi Home Appliances Research Laboratory (72) Inventor Takao Arai 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Home Appliance Research Laboratory, Hitachi, Ltd. (56) References Japanese Patent Laid-Open No. 54-3507 (JP, A)

Claims (1)

[Claims] 1. A rotary head system in which two rotary heads having different azimuth angles are used to record and reproduce an image or a PCM digital signal on each recording track which is sequentially adjacently recorded as an oblique track at a certain angle in the longitudinal direction of the magnetic tape. In the magnetic recording / reproducing apparatus, the track area of each recording track is recorded on the image or PC.
A first area for recording / reproducing an M digital signal, and recording signal switching control means for separately recording in a second area in which only the tracking control signal for the rotary head to trace the track is recorded / reproduced. A timing detection signal of a first frequency is recorded in the second area of every other recording track of each of the recording tracks, and the recording tracks on both sides of the recording track on which the timing detection signal is recorded are recorded. A tracking control signal recording means for recording a pilot signal of a second frequency different from the first frequency in the second area is provided, and tracking of the magnetic tape recorded by the recording signal switching means and the tracking control signal recording means is performed. A control device, which detects the timing detection signal, and the detection device which detects both of the adjacent signals. Timing generating means for generating first and second timings at which the respective pilot signals from the second area of the track are detected; and the second timing of one of the adjacent recording tracks by the first timing signal. A first pilot detecting means for detecting the level of the recorded pilot signal, and a second pilot detecting means for detecting the level of the pilot signal recorded in the other second area of the adjacent recording tracks by the second timing signal. It is characterized by comprising pilot detecting means and control means for controlling the positional relationship between the magnetic tape and the rotary head so that the output signals of the first and second pilot detecting means are at the same level. Rotating head type magnetic recording / reproducing device.