JP2817644B2 - Rotating head type magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type magnetic recording / reproducing apparatus, and more particularly to a rotary head type magnetic recording / reproducing apparatus capable of reproducing a recording medium recorded in a different system such as an NTSC system or a PAL system.

[0002]

2. Description of the Related Art A rotary head type magnetic recording / reproducing apparatus (VT)
In R), there are many devices configured to perform recording and reproduction by alternately using two magnetic heads having different azimuth angles. In such a rotary head type magnetic recording / reproducing apparatus, an auxiliary magnetic head is provided for each of the two magnetic heads so that the magnetic head crosses a plurality of tracks such as fast-forward reproduction and slow-motion reproduction. There is an apparatus that performs reproduction by using the auxiliary magnetic head also at the time of special reproduction in which scanning is performed.

The outline of such a rotary head type magnetic recording / reproducing apparatus will be described below with reference to FIGS.

[0004] As schematically shown in FIG.
Rotation of the rotating head type magnetic recording / reproducing device
Has four magnetic heads 21_A1, 21_B1, 21_B2,
21 _A2Is provided. Of these magnetic heads, the magnetic
Head 21_A1, 21_B1Is the head that is usually used
And the azimuth angles are configured to be different from each other.
Magnetic head 21_A1, 21_B1Provided in the vicinity of
Magnetic head 21_B2, 21_A2Is used during special playback.
The magnetic head 21_B2Is the magnetic head 2
1_A1In contrast, the head has a reverse azimuth,
Head 21_A2Is the magnetic head 21_B1Inverse Azima
Head.

[0005] Like fast forward playback and slow motion playback
During the special playback, the magnetic head 21 _B1, 21_A1By
On the track to be read, the magnetic head 21_A1, 2
1_B1Scanning may occur, but the auxiliary magnetic head
Good 21_B2, 21_A2Are the magnetic heads 21_A1,
21_B1So that tracks that cannot be read
Is placed.

That is, the magnetic head 21 is attached to the rotating head.
_A1, 21 _{if B1} has only two provided with, for example, a magnetic head 21 _A1 is, when crosses the track to be read by the magnetic head 21 _B1 is so that the reproduction output can not be obtained, by providing the auxiliary magnetic heads as described above, when no reproduced output is obtained from the magnetic head 21 _A1 will become the reproduced output from the magnetic head 21 _B2 is obtained, it is possible to better play.

In order to realize such reproduction, it is necessary to select the reproduction output from two magnetic heads. In the conventional rotary head type magnetic recording / reproducing apparatus, the selection is made as follows.
This is performed using the following circuit.

FIG. 4 shows a schematic configuration diagram of a conventional selection circuit.
You. Amplifier 12_A1, 12_B1, 12_A2, 12_B2Each
And the magnetic head 21_A1, 21_B1, 21_A2, 21_B2Output
Is an amplifier for amplifying the signal, as shown in FIG.
Amplifier 12_A1, 12_B1Output from the switching circuit 13₁Enter in
And the amplifier 12_A2, 12_B2Output from the switching circuit 13 _Two
Has been entered.

Switching circuits 13 ₁ and 13 ₂ have terminals P
₃ , a switching signal synchronized with the rotation phase of the rotating head is also input. Each switching circuit 13 outputs the output of the magnetic head 21 in contact with the magnetic tape 22 and in the reproducing state based on the switching signal. , A switching circuit 16 and a comparison circuit 15 (the comparison circuit 15 is supplied to the comparison circuit 15 via the amplifier 14).

That is, at the time of special reproduction, as shown schematically in FIG. 5, two signals S ₁ ′ and S ₂ ′ (for example, the magnetic head 21 _A1) whose magnitude relation changes with time are supplied to the comparison circuit 15. And a signal obtained by amplifying the reproduction output of 21 _B2 ).

The comparing circuit 15 outputs these signals S ₁ 'and S
A signal corresponding to the magnitude relation of ₂ 'output from the terminal P _1, switching circuit receives an input of the signal through the terminal P ₂ passage 16
Outputs the signal S having the higher signal level from the terminal P _{OUT. In} order to stably switch between the signals S ₁ and S ₂ , the comparison circuit 15 outputs the signal S ₁ '
The level difference S ₂ 'is, only when the changes over the level difference T that is set in advance, the operation such as changing the level of the output signal, the circuit having a hysteresis is used.

[0012]

As described above, in a conventional rotary head type magnetic recording / reproducing apparatus having a selection circuit as described above, a rotary head type magnetic recording apparatus having only a pair of heads has been already described. Since more information can be used during special playback compared to playback devices,
Better reproduction can be performed.

However, using a conventional selection circuit,
For example, NTSC (National Televison System Commi
When a magnetic tape on which recording is performed by different methods, such as Ttee) and PAL (Phase Altenation by Line), is reproduced, the following problems occur.

The details of the above problem will be described with reference to FIGS. As described above, the comparison circuit 15 changes the level of the signal output to the terminal P ₁ only when the level difference between the signals S ₁ ′ and S ₂ ′ changes by a level difference T or more that is set in advance. For example, the signals S ₁ ′ and S ₂ ′ input to the comparison circuit 15 are used.
However, if the signal is as shown in FIG. 6A, signal switching is performed at the point indicated by “A” in the figure, and as a result, the reproduced signal output from the switching circuit 16 is ,
The result is as shown in FIG.

Here, it is assumed that the signal level input to the selection circuit is lowered as a whole as shown in FIG. In this case, the comparison circuit 15 also outputs the signal S
Level difference ₁ 'and S _2' is the level difference T that is set in advance
Only when changes above, it changes the level of the signal output to the terminal P _1. For this reason, the comparison circuit 15 instructs the signal switching at the point indicated by "b" in the figure, and the reproduced signal output from the switching circuit 16 becomes as shown in (d). Become.

That is, in the conventional selection circuit, when the input signal level (output signal level of the magnetic head) decreases, for example, when reproducing a magnetic tape of a different recording method, the switching is performed with a delay. That is, the selection circuit outputs a signal in a section where the reproduction signal level is small. As a result, when the reproduction signal level is low, good reproduction cannot be performed as in the case where the reproduction signal level is high.

As a technique for solving such a problem, as described in Japanese Patent Application Laid-Open No. 61-92083, it is also possible to provide an external component to the selection circuit. However, in the case of using external components, there is a problem that the components must be selected and adjusted each time in consideration of the variation of the selection circuit configured as an integrated circuit.

Accordingly, an object of the present invention is to provide a rotating head type magnetic device which does not require selection and adjustment of components, has a simple circuit configuration, and can obtain a good reproduction signal even on recording media having different reproduction signal levels. An object of the present invention is to provide a recording and reproducing device.

[0019]

According to the first aspect of the present invention,
(A) First and second heads for performing azimuth recording on a recording medium, and information stored in tracks that cannot be read by the first head among tracks scanned by the first head during special reproduction such as double-speed reproduction. For the first
A first auxiliary head provided near the magnetic head, and a second auxiliary head provided for reading information stored in a track which cannot be read by the second head among tracks scanned by the second head during special reproduction. (B) a reproduction control signal head for reading a reproduction control signal recorded on a recording medium, and (c) a first head in synchronization with the rotation of the rotation head. Selection output means for selectively outputting the output of the first auxiliary head or the outputs of the second head and the second auxiliary head; and (d) one of two signals output by the selection output means. Switching means for outputting a signal and, when the level difference between the two signals exceeds a set value, switching the output signal;
(E) a set value changing means for changing a set value used in the switching means for judging signal switching in accordance with the reproduction control signal read by the reproduction control signal head;

That is, according to the first aspect of the present invention, the type of the recording medium to be reproduced is determined based on the reproduction control signal, and the condition used for signal selection is changed according to the result of the determination. The rotary head type magnetic recording / reproducing apparatus is configured as described above. Thereby, for example, NTS
It is possible to obtain a rotary head type magnetic recording / reproducing apparatus capable of automatically obtaining a good reproduction output from a recording medium on which recording is performed by different methods such as the C method and the PAL method.

As the set value changing means, means for converting the cycle of the reproduction control signal into a voltage and changing the set value based on the converted voltage can be used.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.

FIG. 1 shows a schematic configuration of a selection circuit used in a rotary head type magnetic recording / reproducing apparatus according to one embodiment of the present invention. As is apparent from FIG.
The conventional selection circuit described with reference to FIG.
, Switching circuit 18, NTSC reference voltage generating circuit 19, and PA
An L reference voltage generation circuit 20 is added, and a circuit that can change the conditions used for comparison by a signal from the switching circuit 18 is used as the comparison circuit 15.

Terminal P connected to voltage conversion circuit 17
Reference numeral ₄ denotes a terminal to which a reproduction control signal (the output of the reproduction control signal head 23 shown in FIG. 3) is input. The voltage conversion circuit 17 is a circuit that outputs a voltage corresponding to the pulse width of the input signal. ing.

That is, when a tape recorded in the NTSC mode is reproduced in the NTSC mode, the pulse cycle of the reproduction control signal is 33 mm / sec, and the PAL
When the tape recorded in the mode is reproduced in the NTSC mode, the pulse cycle of the reproduction control signal is 48 m
m / sec, and the tape recorded in PAL mode is
When reproducing in the TSC mode, the pulse cycle of the reproduction control signal is 48 mm / sec. When reproducing the tape recorded in the NTSC mode in the PAL mode, the pulse cycle of the reproduction control signal is 28 mm / sec. The voltage conversion circuit 17 is a circuit that outputs a voltage corresponding to the pulse period.

The NTSC reference voltage generation circuit 19 and P
The AL reference voltage generation circuit 20 performs the following operations when reproducing magnetic tapes stored in the NTSC mode and the PAL mode, respectively.
The comparison circuit 15 is a circuit for generating a reference voltage suitable for signal comparison, and the switching circuit 18
It is configured to supply a signal from one of the reference voltage generation circuits to the comparison circuit 15 in accordance with an input from the voltage conversion circuit 17.

As described above, it is possible to determine whether the magnetic tape is stored in the NTSC mode or the PAL mode in accordance with the output of the voltage conversion circuit 17. At the time of
The output of the TSC reference voltage generation circuit 19 can be supplied to the comparison circuit 15, and in the PAL mode, the output of the PAL reference voltage generation circuit 20 can be supplied to the comparison circuit 15. Upon receiving the input, the comparison circuit 15 changes the switching characteristics according to the input.

That is, when the input signal level is high, the comparison circuit 15 determines that the level of the signal output to the terminal P ₁ is different when the level difference between the two input signals becomes T ₁ , When the level is low, when the level difference between the two input signals becomes T ₂ (T ₂ <T ₁ ), the operation is performed so that the level of the signal output to the terminal P ₁ is different.

Therefore, in the rotary head type magnetic recording / reproducing apparatus of the embodiment, as shown schematically in FIG. 2, even when the input signal level from each magnetic head is low (c, d), the input signal When the level is large (a, b),
At the same timing, signal switching will be executed,
Good reproduction can always be performed.

[0030]

As described above in detail, according to the present invention, the type of the recording medium to be reproduced is determined based on the reproduction control signal, and the signal selection is performed in accordance with the determination result. If the rotary head type magnetic recording / reproducing apparatus is configured so that the conditions used for the recording are changed, a simple circuit configuration can be used, for example, for a recording medium having a different reproduction output such as the NTSC system and the PAL system. As a result, a rotary head type magnetic recording / reproducing apparatus capable of obtaining a reproduction signal is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a selection circuit used in a rotary head type magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram illustrating an operation of the selection circuit according to the embodiment.

FIG. 3 is a schematic diagram showing a configuration of a rotary head used in a rotary head type magnetic recording / reproducing apparatus.

FIG. 4 is a block diagram showing a configuration of a selection circuit used in a conventional rotary head type magnetic recording / reproducing apparatus.

FIG. 5 is a signal waveform diagram illustrating an operation of a conventional selection circuit.

FIG. 6 is a signal waveform diagram for explaining a problem of a conventional selection circuit.

[Explanation of symbols]

 12, 14 Amplifier 13, 16, 18 Switching circuit 15 Comparison circuit 17 Voltage conversion circuit 19 NTSC reference voltage generation circuit 20 PAL reference voltage generation circuit 21 Magnetic head 22 Magnetic tape 23 Head for reproduction control signal

Claims (3)

(57) [Claims] 1. A first and a second head for performing azimuth recording on a recording medium and a track which is not read by the first head among tracks scanned by the first head during special reproduction such as double-speed reproduction. A first auxiliary head provided near the first magnetic head for reading information; and a first auxiliary head provided for reading information stored in a track which cannot be read by the second head among tracks scanned by the second head during trick play. A rotary head including a second auxiliary head provided in the vicinity of the second magnetic head, a read control signal head for reading a read control signal recorded on the recording medium, and a head synchronized with the rotation of the rotary head. To selectively output the output of the first head and the first auxiliary head or the output of the second head and the second auxiliary head. Output means; and switching means for outputting one of the two signals output by the selection output means, and switching the output signal when the level difference between the two signals exceeds a set value. And a setting value changing means for changing a setting value used by the switching means to determine signal switching in accordance with the reproduction control signal read by the reproduction control signal head. Rotating head type magnetic recording / reproducing device. Wherein said set value changing means, converts the period of the reproduced control signal to a voltage, based on the converted voltage, and characterized in that for changing the said set value according
Item 4. A rotary head type magnetic recording / reproducing apparatus according to Item 1 . Setting value to be changed by the method according to claim 3, wherein said set value changing means, and characterized in that the recording medium recorded by the PAL system and the NTSC system 請
The rotary head type magnetic recording / reproducing apparatus according to claim 1 or 2 .