JPH0719328B2 - Rotating magnetic head - Google Patents

Description

The present invention relates to a rotary magnetic head suitable for use in a video tape recorder capable of recording and reproducing on a metal powder tape at a plurality of tape speeds.

[Outline of Invention]

The present invention relates to a rotating magnetic head for a video tape recorder capable of recording and reproducing on a metal powder tape at a plurality of tape speeds, in which a double azimuth head in which a metal head and a ferrite head are arranged close to each other is rotated. By installing two sets on the head drum, separated by 180 degrees,
A rotary magnetic head capable of inexpensively obtaining a good image and a low-noise image at a plurality of tape speeds.

[Conventional technology]

Conventionally, a double azimuth head, in which two magnetic heads having different azimuth angles are arranged close to each other, is used as a rotating magnetic head for a video tape recorder for recording / reproducing at a plurality of tape speeds. There are two sets that are isolated. FIG. 1 is a view showing such a rotating magnetic head. The rotating head drum (1) to which the magnetic head is attached has one side where the first and second magnetic heads (2) and (3) are close to each other. , 180 ° apart, the third and fourth magnetic heads (4) and (5) are close to each other, and the first magnetic head (2), the third magnetic head (4) and the second magnetic head are located. (3) and the fourth magnetic head (5) are located symmetrically with respect to the rotation center O. And each magnetic head (2), (3),
The azimuth angles of (4) and (5) are different between the first and second magnetic heads (2) and (3) and the third and fourth magnetic heads (4) and (5) which are close to each other. The first and third magnetic heads (2) and (4) and the second and fourth magnetic heads (3) and (5), which are azimuth angles and are symmetrical with respect to the rotation center O, also have azimuth angles. Is wrong. That is, one is the azimuth angle A,
Letting the other be the azimuth angle B, the first and fourth magnetic heads (2) and (5) are the azimuth angle A, and the second and third magnetic heads (3) and (4) are the azimuth angle B. . Here, for example, in the case of a video tape recorder for recording / reproducing at two kinds of tape speeds, the first and third magnetic heads (2) and (4) are set to the first tape speed (hereinafter referred to as standard mode). Corresponding gear gap widths are provided, and the second and fourth magnetic heads (3) and (5) are gear gap widths corresponding to a second tape speed (hereinafter referred to as a long time mode) lower than the first tape speed. More specifically, the first
The magnetic head (2) has a gear step width such that crosstalk between tracks does not become a problem during variable speed reproduction of slow mode, still mode, etc. in the long time mode, and a good image is obtained in recording and reproduction in the standard mode. The magnetic head (3) of the third magnetic head (4) has such a gear width that the crosstalk between tracks does not become a problem during the reproduction in the long time mode, and a good image can be obtained in the still reproduction in the standard mode. Is a gear width that allows a good image to be obtained during recording and reproduction in the standard mode, and the fourth magnetic head (5) may have a gear width such that crosstalk between tracks does not pose a problem during long-time mode reproduction. When normal recording / reproducing is performed in the standard mode, the tape is alternately scanned by the first and third magnetic heads (2) and (4), and normal recording / reproducing is performed in the long-time mode. In this case, the second and fourth magnetic heads (3) and (5) are alternately scanned on the tape. Also,
During variable speed reproduction such as still reproduction, slow reproduction, and high speed search, the combination of two magnetic heads used alternately is appropriately changed. An example of the combination of the two magnetic heads used alternately will be shown below.

By properly changing the combination of magnetic heads used as shown in the above table, you can use dedicated magnetic heads for standard mode recording / playback and long-time mode recording / playback, respectively. A good image can be obtained. Also, during still playback and high-speed search,
Since the tape speed is different from that during recording, the difference between the track recorded on the tape and the track of the magnetic head is dealt with by changing the scanning magnetic head, and the noise generation during variable speed reproduction is reduced. is doing.

On the other hand, with the recent increase in recording density of video tape recorders, high coercive force tapes such as metal powder tapes have been developed and put to practical use in so-called 8 mm videos. By the way, the metal powder tape causes a saturation phenomenon at the time of recording in a magnetic head using ferrite, and the characteristics as a high coercive force tape cannot be fully utilized. Therefore, a metallic magnetic head using a ferromagnetic metal such as sendust or amorphous having a high saturation magnetic flux density is used as a core material.

[Problems to be solved by the invention]

However, there is a drawback that the ferromagnetic metal such as sendust and amorphous is very expensive, and the magnetic head made of ferromagnetic metal is several times as expensive as the magnetic head made of ferrite. In particular, as a video tape recorder using a metal powder tape, when a double azimuth head is composed of four magnetic heads as shown in the above-mentioned example of FIG. 1, the expensive metal-based magnetic head is twice as large as usual. Since the number of individual pieces is also required, the cost required for the magnetic head structure is significantly increased.

The present invention has been made in view of the above points, and an object thereof is to provide a rotating magnetic head capable of inexpensively forming a double azimuth head using four magnetic heads.

[Means for solving problems]

The rotary magnetic head of the present invention is a rotary magnetic head capable of recording and reproducing on a metal powder tape at a plurality of tape speeds. In the rotating magnetic head, recording and reproducing metal heads (3) and (5) and this metal system head can be used. Heads (2) and (4) for reproduction of reverse azimuth, which are different from heads (3) and (5)
Two sets of double azimuth heads arranged in close proximity to each other are provided on the rotary head drum (1) at an angle of 180 °.

[Action]

The rotating magnetic head of the present invention can perform recording on a metal powder tape at a plurality of tape speeds satisfactorily without causing a saturation phenomenon by performing recording with two metal-based heads, and at the same time, for reproduction, a metal-based head and a ferrite system. By doing both heads, a double azimuth head for a video tape recorder can be constructed that produces good and noise-free images at multiple tape speeds.

〔Example〕

An embodiment of the rotating magnetic head of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a double azimuth head composed of four magnetic heads as described in the conventional example. The rotary magnetic head of this embodiment is the rotary magnetic head of FIG. 1 in which the first and third magnetic heads (2) and (4) are ferrite magnetic heads having a core of ferrite. The fourth magnetic heads (3) and (5) are metal magnetic heads having a core made of a metal such as amorphous or sendust. Each magnetic head (2),
With regard to the gap widths of (3), (4) and (5), for example, the standard mode video track width is 20μ and the long time mode video track width is 10μ among recording / reproducing at two kinds of tape speeds. Then, the first magnetic head (2) ... 20 .mu. Second magnetic head (3) ... 13 .mu. Third magnetic head (4) ... 25 .mu. Fourth magnetic head (5) ... 13 .mu.

The circuit connected to the rotating magnetic head configured as above,
This will be described below. In FIG. 2, (2), (3),
(4) and (5) show the above-mentioned first, second, third and fourth magnetic heads. Further, in FIG. 2, (6) shows a recording system video signal processing circuit, and a recording signal obtained by the recording system video signal processing circuit (6) is passed through amplifier circuits (7) and (8). Supply to the second and fourth magnetic heads (3) and (5). Further, the reproduction signals obtained at the second and fourth magnetic heads (3) and (5) are supplied to the first and second switching switches (13) and (13) through the amplifier circuits (9) and (10), respectively. One fixed contact (13b) and (14) of (14)
b) and one of the input terminals of the head switch discrimination circuits (19) and (20). The reproduction signals obtained in the first and third magnetic heads (2) and (4) are transferred to the first and second switching switches (13) and (14) via the amplifier circuits (11) and (12), respectively. ) Other fixed contact (13c) and (14
c) and the other input terminals of the head switching determination circuits (19) and (20), respectively. The movable contacts (13a) and (14) of the first and second switching switches (13) and (14) are then
The reproduction signals obtained in a) are supplied to the reproduction signal input terminals of the reproduction system video signal processing circuit (15). A signal required for mode discrimination in a reproduction signal such as an auto tracking signal and a control track signal obtained by the reproduction system video signal processing circuit (15) is supplied to the mode discrimination circuit (16). Further, the recording mode instruction signal at the time of recording obtained by the recording mode instruction circuit (22) is supplied to the mode discrimination circuit (16). Further, the operation signals for recording, reproduction, still reproduction, high-speed search, etc. obtained by the system control circuit (18) are supplied to the mode discrimination circuit (16) and a head switching control circuit (17) described later. And mode discrimination circuit (16)
Knows whether it is during playback or recording by the operation signal, and when playing back, the signal from the playback system video signal processing circuit (15) and the signal from the recording mode instruction circuit (22) To determine. The mode signal discriminated by the mode discrimination circuit (16) is supplied to the head switching control circuit (17). The head switching discrimination circuits (19) and (20) described above are circuits for discriminating which of the signals supplied to one and the other input terminals has a larger output, and outputting a head switching signal according to this discrimination. is there. The head switching signals of the head switching discrimination circuits (19) and (20) are supplied to the head switching control circuit (17). Reference numeral (21) shows a drum pulse generation circuit, which generates a pulse signal which is switched for each half rotation of the rotary drum, that is, for each scanning period of the magnetic head. The pulse signal of this drum pulse generation circuit (21) is applied to the head switching control circuit (17).
Supply to. The head switching control circuit (17) is the above-mentioned first
And a circuit for controlling the switching of the second switching switches (13) and (14). And the drum pulse generation circuit (21)
The switching of the first and second switching switches (13) and (14) is controlled by determining the supplied mode signal, operation signal and head switching signal every time the pulse signal is switched. The table below shows the combinations of the magnetic heads at the time of reproduction used by connecting the switching switches (13) and (14).

As shown in the above table, the head switch control circuit determines which magnetic head the reproduction signal supplied to the reproduction system video signal processing circuit (15) is, the switching switch (13),
It is controlled by switching (14).

With the above configuration, when recording a video signal, the video signal is supplied from the tuner or the like to the recording system video signal processing circuit (6) at any tape speed in the standard mode and the long time mode, and the recording system is recorded. A video signal is supplied from the video signal processing circuit (6) to the second magnetic head (3) and the fourth magnetic head (5) through the amplifier circuits (7) and (8), and the second and fourth magnetic heads are supplied. Recording is performed alternately on the tape by the magnetic heads (3) and (5).

Next, when reproducing the recorded tape at a normal speed, first, an operation signal designating a normal reproduction speed is supplied from the system controller (18) to the head switching control circuit (17). Then, the speed and the magnetic head (2), (3), either in the standard mode or the long time mode on the tape,
The mode discriminating circuit (16) discriminates whether the recording mode is the standard mode or the long time mode by scanning the scanning signals in (4) and (5), and the discriminating mode signal is sent to the head switching control circuit 17). If it is determined that the mode is the long time mode, the head switching control circuit (17) supplies a switching signal to the first and second switching switches (13) and (14) to move the movable contacts (13a) and (14a) is connected to one fixed contact (13b) and (14b), respectively. When the standard mode is determined, the head switching control circuit (1
In response to the switching signal from 7), the movable contacts (13a) and (14a)
a) is connected to the other fixed contacts (13c) and (14c) respectively. By connecting the first and second switching switches (13) and (14) as described above, in the case of the long time mode, the metallic second and fourth magnetic heads (3) and (5) are connected. ) Supplies the read recording signal to the reproduction system video signal processing circuit (15) through the amplification circuits (9) and (10). In the standard mode, the first and third ferrite systems are supplied.
The read recording signal is supplied from the magnetic heads (2) and (4) to the reproducing system video signal processing circuit (15) through the amplifier circuits (11) and (12). By supplying this recording signal,
A video recording signal is reproduced by connecting the reproduction system video signal processing circuit (15) to a television receiver or the like.

When reproducing the recorded tape next, first, an operation signal designating still reproduction is supplied from the system controller (18) to the head switching control circuit (17). And
The mode is discriminated by a signal from any one of the magnetic heads (2), (3), (4) and (5) to the mode discrimination circuit (16) via the reproduction system video signal processing circuit (15), According to the discriminated mode, the head switching control circuit (17) controls the first and second switching switches (13) and (1).
4) Connect. That is, in the long time mode, the movable contact (13a) of the first switching switch (13) is connected to the other fixed contact (13c) and the movable contact (14a) of the second switching switch (14) is connected. ) Is connected to one fixed contact (14b), and the recording signals read by the first magnetic head (2) and the fourth magnetic head (5) are amplified by amplifier circuits (11) and (1).
It is supplied to the reproduction system video signal processing circuit (15) via (0) and the still video recording signal is reproduced. In the standard mode, the movable contact (13) of the first switching switch (13)
a) is connected to one fixed contact (13b), the movable contact (14a) of the second switching switch (14) is connected to the other fixed contact (14c), and the second magnetic head (3) is connected. The recording signal read from the third magnetic head (5) is supplied to the reproducing system video signal processing circuit (15) via the amplifier circuits (9) and (12), and the stationary video recording signal is reproduced.

When performing a high speed search next, first, the system controller (18) supplies a forward or reverse high speed search operation signal to the head switching control circuit (17), and the mode discrimination circuit is operated in the same manner as at other speeds. The signal from (16) is used to discriminate between standard and long time. During this high-speed search, the output signal from the first magnetic head (2) via the amplifier circuit (11) and the output signal from the second magnetic head (3) via the amplifier circuit (9) are sent to the head. Switching discrimination circuit (19)
And the control signal is supplied to the head switching control circuit (17) so that the first switching switch (13) is connected to the magnetic head side having a large output signal. In addition, an output signal from the third magnetic head (4) via the amplifier circuit (12) and an output signal from the fourth magnetic head (5) via the amplifier circuit (10) are switched to a head switching determination circuit ( 20), the control signal is supplied to the head switching control circuit (17) so that the second switching switch (14) is connected to the magnetic head side having a large output signal. The head switching control circuit (17) is supplied with the control signals from the respective head switching determination circuits (19) and (20).
Switches the first and second switching switches (13) and (14) in synchronism with the rotation of the drum from the rotary drum (21), that is, in synchronization with the pulse signal switched by switching the head.
By connecting the first and second switching switches (13) and (14) in this way, a recording signal with a large output signal is always supplied to the reproduction system video signal processing circuit (15), and high-speed search is performed. The video recording signal of is reproduced.

As described above, the use of the magnetic head as described above is different from the conventional one in that the second and fourth magnetic heads (3) and (5) are used in both the standard mode and the long time mode during recording. The first and third magnetic heads (2),
(4) is a reproduction-only head. Since the second and fourth magnetic heads (3) and (5) have a gear width of 13 μ as described above, they may be slightly overlapped when recording in a long mode with a track width of 10 μ. Although recorded, there is no problem with crosstalk between tracks at this level and there is no problem. Also, there is a guard band in which no signal is recorded when recording in the standard mode with a track width of 20μ, but during playback, a magnetic head that matches the track width in the standard mode is used, so that the video track is scanned reliably. Therefore, it is possible to obtain a good reproduced image as in the conventional case. Furthermore, during variable speed reproduction, a reproduced image with less noise can be obtained as in the conventional case.

As described above, although two of the four magnetic heads (2) and (4) are dedicated to reproduction,
It is possible to obtain a good reproduced image or a reproduced image with less noise as in the conventional case. For this reason, when a metal powder tape is used as a video tape recorder using this head configuration, only two expensive metal-based heads are required, and the other two are only for playback, so a metal powder tape is used. Even at that time, an inexpensive ferrite head that can be used for regeneration can be used, and the cost for head construction can be reduced. Further, since the connection from the recording system video signal processing circuit (6) to the magnetic head does not need to be connected to the first and third magnetic heads (2) and (4) dedicated to the reproduction, the circuit configuration is accordingly. Will be easier.

Although the video track widths of the standard mode and the long time mode are 20 μ and 10 μ respectively in the above-mentioned embodiment, various other combinations are possible, for example, the video track width of the standard mode and the long time mode is 60 μ, respectively. When 20μ is set, the cap width of each magnetic head is as follows: first magnetic head (2) ... 40μ second magnetic head (3) ... 30μ third magnetic head (4) ... 60μ fourth magnetic head (4) 5) ... It is possible to set it to 30μ. The combination of heads used in each reproduction state is also an example, and for example, high-speed search in the long time mode may be performed only by the combination of the second and fourth magnetic heads (3) and (5). . In any case, a combination that can obtain a good image and an image with less noise is preferable. Furthermore, the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

〔The invention's effect〕

As is apparent from the above embodiments, the rotating magnetic head according to the present invention makes it possible to inexpensively construct a double azimuth head for a metal powder tape, which can obtain a good image and an image with less noise.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the rotating magnetic head of the present invention, and FIG. 2 is a circuit configuration diagram of the example of FIG. (1) is a rotating head drum, (2) is a first magnetic head, (3) is a second magnetic head, (4) is a third magnetic head, and (5) is a fourth magnetic head.

Claims (1)

[Claims] 1. A rotary magnetic head capable of recording and reproducing on a metal powder tape at a first speed and a second speed higher than the first speed, and a first gap width capable of recording and reproduction. A double azimuth head in which a metal-based head having the following and a ferrite-only head for reproduction having a second gap width wider than the first gap width and having a reverse azimuth with the metal-based head are arranged in proximity to each other are provided. , Two sets are provided on the rotary head drum, separated by 180 degrees, and the metal-based head is used as a recording head at the first and second speeds and a reproducing head at the second speed, and the ferrite-based head is used as the first head. A rotary magnetic head characterized by being a read-only head at a speed of 1.