JPH0656684B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to, for example, a control track of a video tape (hereinafter referred to as “CTL track”), an address signal together with a control signal (hereinafter referred to as “CTL signal”), and the like. The present invention relates to a magnetic recording / reproducing apparatus for recording the information signal of the above on a magnetic tape.

[Prior Art] FIG. 3 is a block diagram of a control signal recording / reproducing system of a conventional magnetic recording / reproducing apparatus shown in, for example, Japanese Patent Publication No. 60-48811, which is adapted to rewrite the queue signal recorded on a CTL track. It is a circuit diagram. In the figure
(6) is a control head (hereinafter referred to as "CTL head"), (8) is a first switch, (9) is a control amplifier (hereinafter referred to as "CTL amplifier"), (10) is a positive amplifier, ( 11) is a second switch, (12) is a gate pulse generating means, (13) is a queue signal recording circuit, and (14) is a negative polarity amplifier. FIG. 4 is a signal waveform diagram of each part of this conventional example,
FIG. 5 is a diagram showing a recording pattern on a video tape,
(1) is a video tape, (2) is a video signal recording section, (3) is a CTL track, (4) is a video signal recording track, (7)
Is a control signal (hereinafter referred to as "CTL signal").

Next, the operation will be described. In FIG. 3, a CTL head (6) and a CTL amplifier are provided by a switcher (8) which is the first switching means.
When (9) is connected, as shown in FIG. 5, the CTL track (3) recorded on the side end of the video tape (1) is formed.
The reproduced signal is amplified by the CTL amplifier (9) to obtain a reproduced signal A as shown in FIG. 4 (A). The reproduced signal A is a positive polarity amplifier (10) and a negative polarity amplifier (14). In addition, the positive amplifier (10) has a first amplifier as shown in FIG. 4 (B).
Only the CTL signal B _c that becomes a signal is amplified and output.
The negative polarity amplifier 14 amplifies only the negative polarity signal (not shown) and uses it as the queuing signal Q which becomes the second signal.

The CTL signal B _c output from the positive polarity amplifier (10) is used for controlling the rotating head or the capstan, and is applied to the gate pulse generating means (12), as shown in FIG. 4 (C).
As shown in FIG. 5, a gate pulse g is generated which is delayed from the CTL signal B _c by a certain period of time t and ends before the next CTL signal B _c . This gate pulse g is applied to the switcher (11) which is the second switching means, and when the switcher (11) is turned on by the queuing signal write command signal which is a command to create a new second signal, The gate pulse g operates the switch (8) to output the output of the queue signal recording circuit (13), that is, the third signal for creating a new second signal to the CTL head (6) in the section of the gate pulse g. Only apply.

The queue signal recording circuit (13) generates a recording signal r ₁ as shown in FIG. 4 (D) according to the queue signal write command signal and the desired queue signal Q to be written at that time.
In this example, recording is performed in two sections of the CTL signal B _c . In this example, as shown in FIG. 4 (E), the CTL signal C
And the time interval of the queue signal q ₁ are changed from the previous T ₁ to T ₂ and writing is performed. At this time, first, a signal is applied to the CTL head (6) so that the gate pulse g is generated so that the saturation magnetization has the same polarity as the magnetization already saturated and recorded on the video tape (1) (N pole in this case). To do. The queue signal Q to be written next is delayed from the CTL signal C by the time T ₂ and a signal in the opposite direction to the above is applied to the CTL head (6). This makes the videotape
The magnetization of (1) is reversed (from the saturated N pole to the saturated S pole). This reverse signal ends with the end of the gate pulse g. Since the end point of the gate pulse g is set to the original S pole portion, the S pole is left as it is on the CTL track (3) even when the reverse signal is finished. In this way a new queue signal q ₁ is recorded,
When this is reproduced, a new queuing signal q ₁ is obtained as shown in FIG. 4 (E).

Next, as another example, FIGS. 4 (F) and 4 (G) show a case where the time interval between the CTL signal C and the queue signal q ₂ is T ₃ . In this case as well, a new queuing signal is recorded in the same manner as described above. In the above-mentioned conventional example, the magnetization N pole was inverted to the S pole in the middle, but in this example, as shown in FIG.
CT even if the already recorded N pole ends and becomes S pole
Since signals in the same direction are still applied to the L head (6), the S pole on the CTL track (3) during this period is inverted to the N pole. When the signal applied to the CTL head (6) is inverted by the queue signal Q, the magnetization is inverted to the S pole, and when the signal ends, the original S pole remains as it is.

When this is reproduced, as shown in FIG. 4 (G), the CTL signal C
A new queuing signal q ₂ delayed by a time T ₃ is obtained.

[Problems to be Solved by the Invention] By the way, when recording an address signal or a queuing signal in the CTL track (3) or rewriting an already written queuing signal as described above, the video tape
In addition to the case where (1) is recorded / reproduced on the same VTR, the video tape (1) is rewritten on another VTR as described above and is reproduced on the original VTR again, or 3 When the above recording / reproducing is performed between the VTRs of various units, various compatible recording / reproducing may be performed. When such compatible recording / reproduction is performed, if the width of the CTL head (6) varies among these VTRs, the width of the CTL recording track (3) also varies, and the compatible reproduction is performed. At this time, a false signal is generated, the reading of the queue signal is erroneously performed, and the rotation control of the rotary head or the capstan is disturbed. An example will be described below.

FIG. 6 shows a video tape recorded on a first VTR having a narrow CTL head and a second V tape having a wide CTL head.
It is a figure which shows the case where a queue signal is rewritten over TR and this part is reproduced again by this VTR. That is,
As shown in FIG. 6 (A), the first width of the CTL head is narrow.
The width of the CTL track (3) of the video tape (1) recorded by the VTR of No. 1 is a, and the video tape (1) has a wide CTL head (6) as shown in FIG. V of 2
CTL track when rewriting the queue signal in TR
Assuming that the width of (3) is b and this part is reproduced again by this CTL head (6), as shown in FIG. 6 (A), the saturation magnetization N pole part and In the same manner as described above, the recording signal r shown in FIG.
When applied to the TL head (6), a new saturation magnetization N pole portion and S pole are formed in the densely shaded portion of FIG. 6 (A). As can be seen from this figure, the width b of the newly recorded CTL track (3) is wider than the width a of the original CTL track (3), which is (ba) in this example.
When the video tape (1) having the CTL track (3) thus formed is reproduced on the same CTL head (6), C
The reproduction output of the TL amplifier (9) is CT as shown in FIG. 6 (D).
A false signal s appears in addition to the L signal C and the queue signal q. In this example, the level of the false signal s is relative to the level of the CTL signal C. Becomes The standard value of a is 750 μ in the case of a VHS type VTR, but a variation of about ± 100 μ occurs due to the above-mentioned variation in the CTL head width, misalignment of video tape running, and the like.

Therefore, for example, the false signal s when a = 750 μ and b = (750 + 100) μ is Occurs at the level of. Also, a = (750 + 100) μ, b = (7
In the case of (50 + 100) μ, the false signal s reaches -10 dB.

When the CTL signal C including such a false signal s is amplified by the next positive polarity amplifier (10), the false signal s is also a pulse indistinguishable from the CTL pulse B _{c as} shown in FIG. 6 (E). There is a risk that the output will be B _s, and in such a case the control of the rotary head or the capstan will be disturbed and normal operation will not occur.

The width of the CTL track (3) varies as described above, and the contact state between the CTL head (6) and the video tape (1) also varies, so that the head reproduction output from the CTL track (3) also occurs. There are variations. Therefore, in general, CT
The gain of the L amplifier (9) is set sufficiently large, and when the reproduction output of the CTL head is large, the output of the CTL amplifier (9) reaches the saturation region and the peak of the reproduction output is clipped. In this case, the false signal s substantially increases with respect to the CTL signal C, and the false pulse s is more likely to be generated in the output of the positive polarity amplifier (10). Further, since the reproduction output of the CTL head varies as described above, the output level of the CTL amplifier (9) also naturally varies. Therefore, especially when the output level is lowered due to this output level change. However, the threshold level of the positive polarity amplifier (10) is set sufficiently low so that the positive polarity amplifier (10) can always obtain the CTL output pulse. Therefore, even if the false signal s is small, it is amplified. As a result, a false output pulse is generated.

The above example shows an example in which the false signal s appears with the same polarity as the CTL signal C. However, various combinations of the width of the CTL track and the width of the CTL head in the compatible recording / reproducing, the position of the queuing signal to be rewritten, The position of the original queuing signal before being rewritten (in the above example, the position of the original queuing signal was the position indicated by q ₀ in FIG. 6 (B). , The phase has been changed to a position delayed from q ₀ as shown in q).
May appear with the same polarity as the queue signal q.
In this case, a pulse due to the false signal s is generated in the negative polarity amplifier (14) in addition to the queue signal pulse, and if the queue signal is erroneously read, a problem will occur.

The present invention has been made to solve the above problems, and when rewriting, magnetic recording / reproducing capable of avoiding the influence of spurious signals generated by variations in device dimensions such as the width of the control head. The purpose is to provide a device.

[Means for solving problems]

A magnetic recording / reproducing apparatus according to the present invention is a magnetic recording / reproducing apparatus configured to reproduce a signal including a control signal and a rewritable information signal by a control head, wherein the rewritable information signal is controlled by the control head. After rewriting by the control head, the control signal is reproduced by the control head with a threshold value higher than the maximum permissible value of the false signal generated by the rewriting of the information signal due to the variation of the control head width. Alternatively, it is characterized by including a control signal reproducing system having an amplifier for amplifying the information signal.

[Action]

According to this invention, when the control head reproduces the rewritten information signal,
At the time of the above-mentioned rewriting, it is possible to cut the false signal generated due to the variation of the device size, especially the control head width, etc. by the amplifier of the control signal reproducing system, and the original signal can be recorded even when the compatible recording / reproducing is performed. Only the CTL signal can be reproduced and output.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, the same reference numerals as in the conventional example shown in FIG. 3 indicate the same components, respectively, and (15) is a peak value detection circuit,
(16) is a time constant circuit, and (17) is a variable gain CTL amplifier. FIG. 2 is a waveform diagram for explaining the operation of this embodiment. FIG. 2 (A) shows the output waveform of the variable gain amplifier (17).
The figure (B) shows the output waveform of the positive polarity amplifier (10), and the figure (C) shows the output waveform of the negative polarity amplifier (14).

Next, the operation will be described. The case where the queue signal is rewritten as described in FIG. 3 of the above-mentioned conventional example and the output of the CTL head (6) as described in FIG. 6 is obtained will be described. The method is exactly the same as in the conventional example shown in FIG. The signal reproduced from the CTL head (6) is applied to the variable gain CTL amplifier (17) via the switch (8), and its output A (shown in FIG. 4 (A)).
Is guided to the positive polarity amplifier (10), the negative polarity amplifier (14) and the peak value detection circuit (15). The peak value detection circuit (15) is composed of, for example, a diode and a capacitor, detects the peak value of the CTL signal C ₀ or the queue signal q ₀ , and the detection output is applied to the following time constant circuit (16). Is smoothed by. The smoothed output is returned to the variable gain CTL amplifier (17) as a control signal to control its gain. The gain control is
For example, an amplification transistor is used in the amplification stage that constitutes the variable gain CTL amplifier (17), and the base current is changed to hfe
This is performed by controlling the (current amplification factor) and changing the gain. Variable gain CTL amplifier (17), peak detector circuit (15)
By appropriately selecting the loop gain in the feedback loop control system composed of the time constant circuit (16), the maximum value of the signal output of the variable gain CTL amplifier (17) is close to the saturation level for various input level fluctuations. Can be set to, for example, as shown in FIG. 2 (A), CTL
The peak values of the signal C and the queue signal q can be set to slightly less than the saturation level shown by the dotted line. By doing so, for example, the false signals s ₁ and s ₂ having the levels shown in FIG. 2 (A) are -17.5bB or -10bB as described above with respect to the CTL signal C or the queuing signal q. The peak value of the CTL signal C or the queuing signal q is kept at the saturation level even if the reproduction output fluctuation of the CTL head due to the change of the contact state between the video tape (1) and the CTL head (6) occurs. Hold nearby. The output of the variable gain CTL amplifier (17) thus obtained is the positive polarity amplifier of the next stage.
It is amplified by (10) and the negative polarity amplifier (14). The threshold level Vth of these amplifiers (10), (14) is shown in FIG.
The false signal s ₁ or s ₂ shown in (A) has a level, for example, −10.
By selecting above bB, as shown in FIGS. 2 (B) and (C), the CTL signal C and the queuing signal q respectively.
Only the amplified output pulse B _c , Q is obtained. In this case, allowance should be given to the threshold level Vth, and -10d
If the level is set to a level higher than B, for example, about -6 dB, it is possible to cope with a larger variation.

By doing the above, even when the speed of the tape at the time of reproduction changes and the reproduction output of the CTL head fluctuates, that is, the same effect can be obtained for fast-forward reproduction and slow-motion reproduction. Alternatively, the same effect can be obtained in detecting a queuing signal during fast rewinding. Also, a normal VT that does not have a recording or reproducing function of a queue signal
Also in R, the output of the CTL amplifier (17) can be taken out stably, so that the reliability of the control of the rotary head and the like is further increased.

The time constant circuit (16) in the above embodiment changes the time constant according to the speed of the video tape, that is, fast-forward playback, slow playback, fast-forward, fast-rewind, etc. For example, the time constant may be reduced to speed up the response of the feedback loop.

Further, in the above embodiment, the peak value of the output signal of the variable gain amplifier (17) is set to be near the saturation level, but an amplifier is further inserted after this variable gain amplifier (17), Then, the peak value of the output signal may be set near the saturation level.

As described above, according to the present invention, when the control head reproduces the rewritten information signal, the control signal or the information signal which is the reproduction signal is reproduced at the time of the rewriting. , The false signal can be removed (cut) by amplifying with a threshold value higher than the maximum permissible value of the false signal generated due to the device size, especially the variation of the control head width, etc. Even when recording / reproducing, only the original CTL signal can be reproduced and output, and therefore, the reproduction output can be stabilized without disturbing the rotation control of the rotary head or the capstan. Play.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of this embodiment, and FIG. 3 is a CTL signal recording / reproducing system of an original magnetic recording / reproducing apparatus. Block circuit diagram, FIG. 4 is an output waveform diagram of each part of this conventional example, FIG. 5 is a diagram showing a recording pattern of a video tape, and FIG. 6 is for explaining the reason for generation of a false signal during compatible recording / reproducing. It is a waveform diagram of. (6) ... CTL head, (10) ... positive amplifier, (14) ... negative amplifier, (15) ... peak detection circuit, (16) ... time constant circuit, (17) ... variable gain CTL amplifier. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A magnetic recording / reproducing apparatus configured to reproduce a signal including a control signal and a rewritable information signal by a control head, after rewriting the rewritable information signal by the control head. , When the signal is reproduced by the control head, the control signal or the information signal is amplified with a threshold value higher than the maximum allowable value of the false signal which accompanies the rewriting of the information signal due to the variation of the control head width. A magnetic recording / reproducing apparatus comprising a control signal reproducing system having an amplifier.