JPH09120605A - Magnetic recorder/player - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record pilot signals with specific regularity on a video tape based on an encipher signal and to keep the recorded information secret through a simple constitution. SOLUTION: An enciphering signal is synchronized with an RFSW through a flip-flop circuit 32 and delivered, as a control signal, to a switch SW4. According to the control signal, the switch SW4 selects a pulse having polarity inverted through the RFSW or an inverter 34. Output from the switch SW4 is delivered, as a control signal CS3, to a switch SW3. On the other hand, a switch SW2 is provided with a control signal CS2 obtained by subjecting the RFSW to ÷2 frequency division. When the switches SW2 and SW3 are controlled, subtractors 24a, 24b are fed with frequency signals fa, fb at a predetermined timing and a track, including pilot signals Pa, Pb, is formed on a video tape based on the frequency signals fa, fb.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and more particularly, for example, DAT (Digital Audio Tape recorder).
r), 8 mm VTR, consumer digital VTR, professional digital VTR, etc., the pilot signal is recorded on the magnetic tape based on the encrypted signal and the control pulse whose level is switched for each track, and its magnetic field is recorded. The present invention relates to a magnetic recording / reproducing device that adjusts tracking based on a pilot signal reproduced from a tape.

[0002]

2. Description of the Related Art In order to control tracking when reproducing a magnetic tape, a plurality of types of pilot signals are used in FIG.
A magnetic recording / reproducing apparatus for recording on a helical track has been proposed in the past and has been put to practical use in 8 mm VTR and DAT. Regarding the digital VTR, Japanese Patent Application Laid-Open No. 4-25596 filed on September 10, 1992
No. 9 [G11B 20/14, H03M 7/3
0] discloses an example thereof.

[0003]

Such a magnetic recording / reproducing apparatus is characterized in that anyone can faithfully reproduce the information recorded on the video tape. Therefore, the information recorded on the video tape cannot be reproduced. It was impossible to keep confidential. Here, a method of scrambling the recorded information in order to keep confidentiality and descrambling at the time of reproduction is also conceivable, but this causes a problem that the circuit configuration becomes complicated and costly.

Therefore, a main object of the present invention is to provide a magnetic recording / reproducing apparatus capable of maintaining confidentiality of recorded information with a simple structure. Another object of the present invention is to provide a magnetic recording / reproducing apparatus capable of appropriately adjusting tracking when a specific person reproduces a magnetic tape with confidentiality.

[0005]

According to a first aspect of the present invention, one of a plurality of pilot signals used for tracking adjustment during reproduction is selected based on an encrypted signal and a control pulse whose level is switched for each track. A magnetic recording / reproducing apparatus for recording a plurality of pilot signals on a magnetic tape so that the recording pattern has a predetermined regularity by means of a signal generating means for generating an encrypted signal and a control pulse, and inverting the polarity of the control pulse. Inverter means for generating the inverted pulse thus generated, first selecting means for selecting one of the control pulse and the inverted pulse according to the encrypted signal,
And a magnetic recording / reproducing apparatus including second selecting means for selecting one of the plurality of pilot signals based on the output of the first selecting means.

A second aspect of the present invention reproduces a pilot signal recorded on a magnetic tape so as to have a predetermined regularity based on an encrypted signal and a control pulse whose level is switched for each track, and based on the pilot signal. A magnetic reproducing device for adjusting tracking by means of a signal generating means for generating a decryption signal and a control pulse corresponding to an encrypted signal,
Based on the decoding signal and the control pulse, the first pulse is at a predetermined level only when a track where the pilot signal is continuously recorded is traced and when a track other than the pilot signal is continuously recorded is traced. And a second pulse generating means for generating a second pulse having a predetermined level only when the track on which the pilot signal is recorded is traced based on the decoding signal and the control pulse. A sample pulse generator that generates a sample pulse based on the second pulse, and a sample hold unit that samples and holds a correlation signal that correlates with a pilot signal according to the sample pulse, and adjusts tracking by the sample hold signal. It is a playback device.

[0007]

In the first aspect of the invention, the signal generation means generates the encrypted signal and the control pulse, and the polarity of the control pulse is inverted by the inverter means. Then, the control pulse and the inversion pulse are given to the first selecting means. The first selecting means selects either the control pulse or the inversion pulse according to the encrypted signal, and the second selecting means selects any of the plurality of pilot signals based on the output of the first selecting means. As a result, a plurality of pilot signals are recorded on the magnetic tape so that the recording pattern has a predetermined regularity.

In the second invention, for example, when the pilot signal recorded on the magnetic tape according to the first invention is reproduced, the signal generating means controls the decrypted signal corresponding to the encrypted signal and the same control as in the first invention, for example. Generate pulses and.
The first pulse generating means and the second pulse generating means generate the first pulse and the second pulse based on the decoded signal and the control pulse.
Generate a pulse. Of these, the first pulse becomes high level, for example, only when a track where a pilot signal is continuously recorded is traced and when a track where a signal other than the pilot signal is continuously recorded is traced, and the second pulse Becomes high level, for example, only when the track on which the pilot signal is recorded is traced. The sample pulse generating means outputs a sample pulse that becomes high level, for example, only when a track including a pilot signal is arranged on both sides and a track including a signal other than the pilot signal is traced, the first pulse and the second pulse. , And the sample and hold means samples and holds the correlation signal correlated with the pilot signal according to the sample pulse. As a result, for example, an ATF error signal is output from the sample hold means, and tracking is adjusted according to the ATF error signal.

[0009]

According to the first aspect of the invention, a plurality of pilot signals are recorded on the magnetic tape so that the recording pattern has a predetermined regularity based on the encrypted signal and the control pulse. Then, the tracking during playback is disturbed, and the playback video is also disturbed. That is, the confidentiality of the recorded information can be maintained with a simple configuration.

According to the second invention, since the correlation signal correlated with the pilot signal is sampled and held by the sample pulse based on the decoding signal and the control pulse, and the tracking is adjusted by the sample and hold signal, the confidentiality is maintained. Tracking can be properly adjusted only when a specific person plays the magnetic tape.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a digital V of this embodiment is used.
TR10 includes a parallel / serial conversion circuit 12,
As a result, the digital information word to be recorded on the video tape is converted into serial data and given to the 1-bit digital word adding circuits 14a and 14b. Additional circuit 14a
Adds the 1-bit digital word "0" to the information word, and the adding circuit 14b adds the 1-bit digital word "1" to the digital information word. By thus it is 1-bit digital word "0" and "1" is added, a pilot signal P _b of the pilot signals P _a and frequency f _b of the frequency f _a is inserted into the digital information word. The respective digital information words are then converted by the precoders 16a and 16b into the channel words CW _a and CW _b , which are directly applied to the switching decision circuit 20 and the delay circuit 1
It is applied to the switch SW1 via 8a and 18b.

The switching determination circuit 20 also includes a microcomputer 19
The head switching signal (RFSW), the frequency signals f _a and f _b, and the encrypted signal output from the above are provided. Among them, the encrypted signal is a pulse having a cycle according to the key input signal output from the remote controller 21. That is,
When the key input signal "4" is output by operating the ten-key pad 21a provided on the remote controller 21, the cycle of the encrypted signal is as shown in FIG. 4 (A) as shown in FIG. 4 (C). 4 times (4 m) of RFSW shown in.
The switching determination circuit 20 outputs a control signal CS1 based on these input signals, and the switch SW1 is switched by this control signal CS1. This causes the channel word CW _a or CW from the switch SW1.
_b is output and recorded on the video tape 13 as shown in FIG.

The structure of the switching determination circuit 20 is shown in FIG. H
Channel CW_aAnd CW_bIs the integrating circuit 22
a and 22b, and the integrated data is subtracted by the subtractor 24a.
And 24b. Subtractors 24a and 24b
In addition, the pilot signal P _aAnd P_bSame frequency as
Frequency signal f with_aOr f_bIs switch SW2 and
And the frequency signal f_aOr f_b
The integrated data is subtracted from. The switch SW2
Is the frequency obtained by dividing the RFSW by 1/2 by the 1/2 divider circuit 30.
Control signal CS2 (when FIG. 4 (B) is at high level)
Frequency signal f_aControl signal CS2 is
Frequency signal f at the -level_bSelect Also, Sui
Switch SW3 is output from switch SW4 and
The control signal CS3 shown in (D) becomes high level.
It is turned on when it hits. Output from subtractors 24a and 24b
The applied subtraction data is the square / level detection circuit 26a and
And the subtracted data are squared and
That level is detected. The comparison circuit 28 outputs the detected data
The channel word C that is compared and corresponds to the detection data having a large value
W_aOr CW_bSwitch SW1 to select
The control signal CS1 is output.

It should be noted that the flip-flop circuit 3
2, signal processing in the phase inversion circuit 34 and the switch SW4. The encrypted signal is RFSW shown in FIG.
Is applied to the flip-flop circuit 32, which causes the phase to be synchronized with the RFSW as shown in FIG. The synchronized encrypted signal is given to the switch SW4 as the control signal CS5, and the switch SW4
4 selects an inversion pulse whose polarity is inverted by the RFSW or the inverter 34 according to the control signal CS5. That is, the switch SW4 selects RFSW when the encrypted signal is at the high level, and selects the inversion pulse when the encrypted signal is at the low level. Thereby, the switch S
A control signal CS3 shown in FIG. 4D is output from W4.

The switch SW3 is a control signal CS3.
Is turned on when is at high level, so switch SW3
And the frequency signal f at the timing shown in FIG._aAnd
And f _bIs output. This frequency signal f_aAnd f_bTo
Based on this, the comparison circuit 28 outputs the control signal CS1.
By doing so, as shown in FIG.
Shows the pilot signal P at the timing shown in FIG._a
And P_bIs recorded.

FIG. 3 shows the structure of the reproducing system of the digital VTR 10. The reproduction signal reproduced from the video tape 13 is subjected to noise removal by the pre-filter 36 and then given to the band pass filters (BPF) 38a and 38b.
The pilot signals P _a and P _b are respectively extracted. After that, the levels of pilot signals P _a and P _b are detected by level detection circuits 40 a and 40 _b , and level data is applied to switches SW5 and SW6. Switches SW5 and SW6 connect RFSW to 1 /
It is controlled by the control signal CS4 obtained by dividing the frequency by 2 in the frequency dividing circuit 46.
Therefore, each of the switches SW5 and SW6 selects the level data from the level detection circuit 40a and the level data from the level detection circuit 40b when the control signal CS4 is at the high level, and the level detection circuit when the control signal CS4 is at the low level. The level data from 40b and the level data from the level detection circuit 40a are selected. The selected level data is compared by the comparison circuit 42, and the level difference data is given to the sample hold circuit 44. Sample hold circuit 44
Samples and holds the level difference data according to the sample pulse, and outputs the held data as a tracking control signal. This adjusts the tracking well.

What should be noted is the processing for generating the sample pulse based on the decoded signal and RFSW output from the microcomputer 19. The microcomputer 19 generates RFSW based on a rotation detection signal from a cylinder (not shown), and responds to a key input signal from the remote controller 21.
The decrypted signal is generated in the same manner as the encrypted signal is generated. That is, when the microcomputer 19 receives the key input signal “4”, as shown in FIG.
generate a decoded signal with m). The decoded signal is synchronized with the control signal CS4 by the flip-flop circuit 48 using the control signal CS4 as a clock, and the decoded signal having the phase shown in FIG. 4F is output from the flip-flop circuit 48. This decoded signal is directly applied to the EXOR circuit 50, and is also applied to the EXOR circuit 50 via the delay circuit 52 for one cycle of RFSW. The decoded signal is also input to the EXOR circuit 56, whose output is inverted, via the delay circuit 54 for one half cycle of RFSW. RFSW is also input to the EXOR circuit 56. As a result, the EXOR circuit 50 outputs the data shown in FIG.
4 is output, and the EXOR circuit 56 outputs the pulse shown in FIG.
The pulse shown in (J) is output.

As can be seen from FIGS. 4I and 4J, the EXOR circuit 50 output goes high when the track containing the pilot signals P _a and P _b is traced, and the EXOR circuit 56 output outputs the pilot signal P. It becomes high level when _a and P _b are continuous for 2 tracks and when _a signal not including pilot signals P _a and P _b is continuous for 2 tracks. When the NOR circuit 58 receives such a pulse, the NOR circuit 58 operates as shown in FIG.
The pulse shown in (K) is output as a sample pulse.
This sample pulse consists of pilot signals P _a and P _b.
Has a track including each of them on both sides and is high level only when a track not including the pilot signals P _a and P _b is traced. In accordance with such a sample pulse, the sample hold circuit 44
Sample-holds the comparison data and outputs the held signal as a tracking control signal.

At the beginning of reproducing the video tape 13,
Requires the phase of the control signal CS3 and the decoded signal.
The sushi also looks like Fig. 4 (E) and (F).
Instead, the phase gradually increases as the tracking is adjusted.
Changes, and finally the timing of each signal
It converges like. Digital information word on videotape
When recording, key in the microcomputer 19 from the remote control 21
When the force signal “6” is given, the microcomputer 19 operates as shown in FIG.
As shown in (C), it outputs an encrypted signal with a cycle of 6 m.
You. The switch SW4 follows the phase-adjusted encrypted signal
Select RFSW or inversion pulse with
The control signal CS3 is output. by this,
The tracks formed on the video tape are shown in Fig. 6 (D).
Pilot signal P_aAnd pilot credit
No.P _bIs recorded.

When a key input signal "6" is inputted to the microcomputer 19 from the remote controller 21 when reproducing this video tape, the microcomputer 19 outputs a decoding signal having a cycle of 6 m as shown in FIG. 6 (F). To do. This decoded signal and R
Based on the FSW, the EXOR circuits 50 and 56 output the pulses shown in FIGS. 6 (I) and (J), respectively, and the NOR circuit 58 outputs the pulses shown in FIG.
The sample pulse shown in (K) is generated. FIG.
“K” and “x” shown in (K) represent the phase relationship between the pilot signals P _a and P _b located on both sides of the track corresponding to the rising pulse. That is,
When "x" is shown in the rising pulse, the pilot signal P is provided to the left and right of the corresponding track.
_{When a} track including _a and a track including the pilot signal P _b are formed and the rising pulse indicates “y”, the track including the pilot signal P _b and the track including the pilot and the pilot corresponding to the rising pulse A track is formed which contains the signal P _a .

When a key input signal "468" is output from the remote controller 21 when recording a digital information word on a video tape, the microcomputer 19 causes the cycle to be in the order of 4 m, 6 m and 8 m as shown in FIG. 7C. Generate an encrypted signal that circulates and changes. The phase of this encrypted signal is adjusted by the flip-flop circuit 32, whereby the switch SW
The control signal CS3 changes as shown in FIG. Therefore, the pilot signals P _a and P _b are recorded on the video tape at the timing shown in FIG. When playing this video tape, the microcomputer 1
When the key input signal "468" is given to 9, the microcomputer 19 outputs a decryption signal having the same period as the encrypted signal. By processing the decoded signal and RFSW, each of the EXOR circuits 50 and 52 is processed as shown in FIG.
The pulses shown in (I) and (J) are output, and based on this, the NOR circuit 58 generates the sample pulse shown in FIG. 7 (K).

According to this embodiment, the numeric keypad 2 is used for recording.
When an arbitrary key input signal is given to the microcomputer 19 by operating 1a, the microcomputer 19 generates an encrypted signal corresponding to this. Then, based on this encrypted signal, pilot signals P _a and P _b are recorded on the video tape so as to have a predetermined regularity. When reproducing such a video tape, the sample pulse becomes high level at a predetermined timing only when the same key input signal as that at the time of recording is given to the microcomputer 19. That is, if the key input signal at the time of reproduction is different from that at the time of recording, the sample pulse may rise or the pilot signal P _a may be traced when a track in which the pilot signal P _a or P _b is recorded on only one side is traced in some cases. Alternatively, the sample pulse rises when the track on which P _b is recorded is traced, and the tracking is adjusted based on this, so that the reproduced image becomes messy. As described above, the confidentiality of the recorded information can be maintained with a simple configuration, and the tracking can be appropriately adjusted only when a specific item is reproduced.

The present invention reproduces from a plurality of tracks.
Video for one frame is formed by the reproduced signal
It has a particularly remarkable effect in a digital VTR. Figure
8, a digital VTR 10 according to another embodiment is
Switches SW5 and SW6 are omitted in the playback system
The output of the 1/2 divider circuit 46 is given to the NOR circuit 58.
Digital VT shown in FIGS. 1 and 2 except that
Since it is similar to R10, only different points will be explained
However, duplicate description of similar points will be omitted. FIG.
With reference to the 1/2 divider circuit 46, EXOR circuit 50,
And 56 to the patterns shown in FIGS. 6 (E), (I) and (J).
The AND circuit 58 shown in FIG.
The sample pulse shown is output. Also, a 1/2 divider circuit
46, EXOR circuits 50 and 56 to FIG.
When the pulses shown in (I) and (J) are output, N
From the OR circuit 58, the sample pulse shown in FIG.
Is output. Compared with FIG. 6 (K) and FIG. 7 (K),
As can be seen, the sample pulses in this example are adjacent.
Pilot signal P included in the track_aAnd P _bBut
Only rises when it has a phase corresponding to "x"
Therefore, the polarity of the comparison data from the comparison circuit 42 is inverted.
The switches SW5 and SW6 are not required.

According to this embodiment, since the switches SW5 and SW6 can be omitted, the confidentiality of the recorded information can be maintained with a simpler configuration than the digital VTR 10 of the embodiment shown in FIGS. The tracking can be adjusted appropriately only when In these embodiments, the key input signals "4", "6" and "46".
Although the case where 8 "is given to the microcomputer 19 has been described, it goes without saying that any code can be used as the key input signal. However, when the key input signal" 1 "is given, the control signal CS3 is always high. When the level is reached and the key input signal "2" is given, the control signal CS3 changes every two tracks. In such a case, since tracking adjustment during reproduction is impossible, such a code needs to be avoided. .

Further, in these embodiments, the digital VT is used.
Although described using R, it goes without saying that the present invention can be applied to 8 mm VTR and DAT in addition to consumer and commercial digital VTRs.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a part of an embodiment of the present invention.

FIG. 2 is a block diagram showing a part of FIG. 1 embodiment.

FIG. 3 is a block diagram showing another part of the embodiment of the present invention.

FIG. 4A is a waveform diagram showing RFSW, and FIG.
Is a waveform diagram showing the control signal CS2, (C)
FIG. 4 is a waveform diagram showing an encrypted signal, (D) is a waveform diagram showing a control signal CS3, (E) is a waveform diagram showing a control signal CS4, and (F) is a waveform diagram showing a decrypted signal. Yes, (G) is a waveform diagram showing the output of the delay circuit 54, (H) is a waveform diagram showing the output of the delay circuit 52, (I) is a waveform diagram showing the output of the EXOR circuit 50, (J) is a waveform diagram showing an output of the EXOR circuit 56, and (K) and (L) are waveform diagrams showing a sample pulse.

FIG. 5 is an illustrative view showing a part of the operation of the embodiments in FIGS. 1 to 3;

FIG. 6A is a waveform diagram showing RFSW, and FIG.
Is a waveform diagram showing the control signal CS2, (C)
FIG. 4 is a waveform diagram showing an encrypted signal, (D) is a waveform diagram showing a control signal CS3, (E) is a waveform diagram showing a control signal CS4, and (F) is a waveform diagram showing a decrypted signal. Yes, (G) is a waveform diagram showing the output of the delay circuit 54, (H) is a waveform diagram showing the output of the delay circuit 52, (I) is a waveform diagram showing the output of the EXOR circuit 50, (J) is a waveform diagram showing an output of the EXOR circuit 56, and (K) and (L) are waveform diagrams showing a sample pulse.

FIG. 7A is a waveform diagram showing RFSW, and FIG.
Is a waveform diagram showing the control signal CS2, (C)
FIG. 4 is a waveform diagram showing an encrypted signal, (D) is a waveform diagram showing a control signal CS3, (E) is a waveform diagram showing a control signal CS4, and (F) is a waveform diagram showing a decrypted signal. Yes, (G) is a waveform diagram showing the output of the delay circuit 54, (H) is a waveform diagram showing the output of the delay circuit 52, (I) is a waveform diagram showing the output of the EXOR circuit 50, (J) is a waveform diagram showing an output of the EXOR circuit 56, and (K) and (L) are waveform diagrams showing a sample pulse.

FIG. 8 is a block diagram showing a part of another embodiment of the present invention.

FIG. 9 is an illustrative view showing one portion of an operation in the related art;

[Explanation of symbols]

 10 ... Digital VTR 19 ... Microcomputer 20 ... Switching determination circuit 32, 48 ... Flip-flop circuit 34 ... Phase inversion circuit 52, 54 ... Delay circuit 50, 56 ... EXOR circuit 58 ... NOR circuit

Claims (3)

[Claims] 1. A recording pattern has a predetermined regularity by selecting one of a plurality of pilot signals used for tracking adjustment during reproduction based on an encrypted signal and a control pulse whose level is switched for each track. A magnetic recording / reproducing apparatus for recording the plurality of pilot signals on a magnetic tape, the signal generating means generating the encrypted signal and the control pulse, and generating an inversion pulse by inverting the polarity of the control pulse. Inverter means for selecting, one of the control pulse and the inversion pulse for selecting one of the control pulse and the inversion pulse according to the encrypted signal, and any one of the plurality of pilot signals based on the output of the first selecting means A magnetic recording / reproducing apparatus comprising a second selecting unit for selecting. 2. A pilot signal recorded on a magnetic tape so as to have a predetermined regularity is reproduced based on an encrypted signal and a control pulse whose level is switched for each track, and tracking is performed based on the pilot signal. A magnetic reproducing apparatus for adjusting, wherein the signal generating means generates a decryption signal corresponding to the encrypted signal and the control pulse, when a track in which the pilot signal is continuously recorded is traced, and the pilot signal. A first pulse generating means for generating a first pulse having a predetermined level based on the decoded signal and the control pulse only when a track in which signals other than is continuously recorded is traced, and the pilot signal is recorded. A second pulse, which is at a predetermined level only when a track is traced, is applied to the decoded signal and the control. Second pulse generating means for generating a pulse based on the pulse, a sample pulse generating means for generating a sample pulse based on the first pulse and the second pulse, and a correlation signal correlating with the pilot signal according to the sample pulse. A magnetic reproducing device that includes a sample and hold means for sampling and holding, and adjusts tracking by a sample and hold signal. 3. The first pilot signals having different frequencies
A first track including a pilot signal and a second pilot signal, including the first pilot signal, the second track
In the case where the second track including the pilot signal and the third track including the signals other than the first pilot signal and the second pilot signal are consecutive in a predetermined order,
The apparatus further comprises third pulse generating means for generating a third pulse when the third track is traced, wherein the sample pulse generating means is based on the first pulse, the second pulse and the third pulse. The magnetic reproducing apparatus according to claim 2, which generates