JP2705114B2 - Rotating magnetic head device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides four rotating magnetic heads on a cylindrical drum, and erases information recorded on a tape by a helical scan method with a rotating erase head. And a rotating magnetic head device for recording a new video signal.

[Summary of the Invention]

The present invention relates to a rotating magnetic head device which includes a cylindrical drum and four magnetic heads and records a new video signal while erasing information recorded on a tape by a helical scan method using a rotating erasing head. Sometimes, the angle position on the cylindrical drum of the rotating magnetic head for first recording is set to 0.
゜, 18 in the direction of rotation of the rotating magnetic head
By attaching a rotary erasing head at a position of an angle θ in the range of 0 ° ≦ θ ≦ 270 °, a track can be always erased ahead of a recording head, and a rotating magnetic head device capable of performing good recording can be provided. provide.

[Prior Art] Helical scan type magnetic recording (reproducing) devices include:
Normally, the rotation direction of the rotating magnetic head and the running direction of the magnetic tape are set to the same direction, and the magnetic tape is wound obliquely so as to run from the top to the bottom of the cylindrical drum to form a track in an oblique direction of the tape. There is known a rotary magnetic head provided with a rotary erasing head capable of applying an erasing magnetic field along a recording track in an oblique direction.

FIG. 5A shows two rotating magnetic heads hd1, hd2 and 1
Shows a cylindrical drum having a plurality of rotary erasing heads fe (flying erase heads. A magnetic tape 1 is wound around an angular range of 180 ° or more around the cylindrical drum 2. The rotary magnetic heads hd1, hd2 are wound around the cylindrical drum. Are provided at the same height at an angle of 180 ° to each other.
The rotating magnetic head hd1 is attached at an angle of 90 ° in the rotation direction of the rotating magnetic head. The rotating magnetic head rotates in the direction of arrow R, and the magnetic tape 1 moves in the direction of arrow F.
, A recording track is formed on the magnetic tape 1 by the rotating magnetic head hd1 or hd2 contacting the magnetic tape 1 every time the rotating magnetic head rotates 180 °.

FIG. 5B shows a state in which the rotary head is arranged as shown in FIG. 5A, that is, the first rotary magnetic head hd.
FIG. 2 is a diagram showing a track formed on the magnetic tape 1 as viewed from the direction of the base tape, at the moment when recording starts. If information previously recorded remains on the track TR1 on which recording is performed by the first rotating magnetic head hd1, an inconvenience occurs during reproduction. Therefore, the information is stored before the first rotating magnetic head hd1 performs recording. Must be erased, so that the rotary erase head fe is the first rotary magnetic head.
The erase operation is performed prior to hd1. The erasing width of the rotary erasing head fe is twice the recording width of the rotating magnetic head, and the two tracks TR1 and TR2 are simultaneously erased, so that the information in the hatched portions is erased. The gap edge of the rotary erase head fe must coincide with the side edge of the track TR1, but on the cylindrical drum 2, the first rotary magnetic heads hd1 and hd1
Since there is an angle difference of 0 °, the rotating magnetic heads hd1 and hd2 must be mounted at a position higher than the height A of the gap edge. The height difference h is represented by h = θ / 180 ° × Tp (1). Where θ is the first rotating magnetic head hd1
Is 90 ° in this case, and Tp is the recording track width of the rotating magnetic head, which is 20.5 μm according to the 8 mm VTR standard.

Subsequently, in the state of FIG. 6 (a) in which the rotating magnetic head has rotated 180 ° in the R direction, the formed track is shown in FIG. 6 (b). The recording of the track TR1 has been completed by the first rotating magnetic head hd1, and the recording is started on the track TR2 by the second rotating magnetic head hd2. The rotating erase head hd is in a non-contact state with the magnetic tape 1, but there is no problem because the track TR2 has already been erased.

Subsequently, while the rotary magnetic head rotates 180 ° in the R direction, information is recorded on the track TR2 by the second rotary magnetic head hd2, and at the moment when the second rotary magnetic head hd2 ends recording, The one rotating magnetic head hd1 is at the recording start position of the next track, and the recording is performed sequentially in the same manner as in the state shown in FIG.

Incidentally, in a VTR having such a configuration, a method for reducing the size of the cylindrical drum in comparison with a standard VTR in order to reduce the overall configuration is disclosed in
Started with 4-89612.

In this method, as shown in FIG. 7 (a), four rotating magnetic heads HD1, HD2, HD3 and HD4 are arranged at the same height on a cylindrical drum 2 while maintaining a 90 ° angular equidistant interval from each other. Then, while reducing the drum diameter of the cylindrical drum 2 to 2/3 times the standard drum diameter, the magnetic tape 1 is wound around the cylindrical drum 2 at a winding angle of approximately 270 ° to reduce the rotation speed of the rotary magnetic head. Speed up 3/2 times.

Here, the azimuth angles of the first and third rotating magnetic heads HD1 and HD3 are selected to be positive angles (for example, + 7 °),
If the azimuth angle of the fourth rotating magnetic heads HD2 and HD4 is selected to be a negative angle (for example, -7 °), the rotating magnetic heads HD1, HD2, and HD are sequentially rotated while the rotating magnetic head rotates three times.
3. By scanning the four recording tracks TR1, TR2, TR3 and TR4 by the HD4, a track pattern having the same format as described above with reference to FIG. 5 can be formed.

That is, as shown in FIG. 7 (b), when the rotating magnetic head rotates 270 ° in the R direction, the recording track T
When R1 is formed by the first rotating magnetic head HD1,
The next 270 ° rotation forms the recording track TR2 on the recording track TR2 by the second rotating magnetic head HD2, followed by a 270 ° rotation forming the recording track TR3 by the third rotating magnetic head HD3, followed by a 270 degree rotation. Recording track TR4
Is formed by the fourth rotating magnetic head HD4. Therefore, these four recording tracks TR1, TR2, TR3 and TR4 are scanned by the rotating magnetic heads HD1, HD2, HD3 and HD4 once each time the rotating magnetic head rotates 1080 °, that is, three rotations.

[Problems to be solved by the invention]

In the rotating magnetic head device thus configured, similarly to the case described above with reference to FIG. 5, when recording is performed by each rotating magnetic head, information already recorded on the track must be erased. For,
It is necessary to provide a rotary erase head so that the erase operation is performed prior to the recording operation. In order to erase four tracks TR1, TR2, TR3 and TR4 simultaneously during one erasing operation, that is, while the rotating magnetic head rotates 270 °, the gap width of the rotating erasing head should be four times the recording track width. , And it takes time and effort to design and manufacture a new rotary erase head, resulting in an increase in cost. Therefore, a rotating erase head having an erase gap width almost twice the recording track width, as conventionally used, is used.

By the way, when the rotary erasing head is mounted on the cylindrical drum 2, the rotary erasing head can be mounted in four ranges between the rotary magnetic heads HD1, HD2, HD3 and HD4, but it is necessary to consider the height with respect to the rotary magnetic head. . When the magnetic recording apparatus starts recording, the first rotating magnetic head that performs recording first is determined by a predetermined circuit in the magnetic recording apparatus. When the point at which the first rotating magnetic head is installed on the cylindrical drum 2 is defined as a reference 0 °,
Assuming that the mounting angle position of the rotary erasing head is θ in the rotation direction of the rotary magnetic head, the height difference h between the rotary erasing head and the rotary magnetic head is given by: h = θ / 270 ゜ × Tp (2) expressed. Here, Tp is the recording track width.
Since the magnetic tape 1 runs obliquely from top to bottom with respect to the cylindrical drum 2, the rotating erase head is mounted at a position higher by h than the rotating magnetic head to perform the erasing operation prior to the rotating magnetic head. There must be.

However, for example, in FIG. 7A, between the fourth rotating magnetic head HD4 and the first rotating magnetic head HD1,
That is, when the rotary erasing head is mounted in the range of 270 ° ≦ θ ≦ 360 °, the height difference h becomes one track width or more. If the difference between the height of the rotating magnetic head and the rotating erase head is large, the contact between the magnetic tape and the rotating magnetic head may be insufficient, or the head may be removed from the microscope's field of view to adjust the head height during manufacturing. The inconvenience of coming off occurs. Therefore, the rotation erasing head is mounted at
However, depending on the mounting angle Suita, there is a problem that the track just recorded is erased.

For example, a case will be described in which the rotary erasing head is mounted at an angular position of θ = 45 °.

FIG. 8 (b) shows the state shown in FIG. 8 (a), that is, the track at the moment when the first rotating magnetic head HD1 starts recording. The first rotating magnetic head HD1 is located at the recording start point of the first track TR1, and the other rotating magnetic heads HD2, HD3, HD4 are arranged at the same height A on the cylindrical drum 2. The rotating magnetic heads HD2, HD3, and HD4 are in contact with the magnetic tape 1, but do not perform recording because no signal is applied. On the track, the rotary erase head FE
Is located 45 ° ahead of the first rotating magnetic head HD1, and the portions indicated by oblique lines of the tracks TR1 and TR2 have already been erased. The gap edge of the rotating erase head FE is
Since it must coincide with the side end of the first track HD1, it needs to be mounted on the cylindrical drum 2 at a position higher by H than the height of the gap edge of the rotary magnetic head.

Next, FIG. 9B shows the track in the state of FIG. 9A in which the rotary magnetic head has rotated 270 ° in the R direction. New information is recorded on the first track TR1 by the first rotating magnetic head HD1, and new information is recorded on the second track TR1.
At the recording start point No. 2, a second rotating magnetic head HD2 is provided. The past information on the second track TR2 has already been erased, and the rotary erase head FE is at a position where it is not in contact with the magnetic tape 1.

Subsequently, the first rotation of the rotating magnetic head 270 ° in the R direction
FIG. 10 (b) shows the track in the state shown in FIG. 10 (a). New information is recorded on the second track TR2 by the second rotating magnetic head HD2, and the third track TR2
The third rotating magnetic head HD3 is disposed at the third recording start point. By the way, since the rotating erase head FE only needs to erase four tracks while the rotating magnetic head rotates three times, it is sufficient to erase 4/3 tracks in one erasing operation. However, since the gap width of the rotary erasing head FE is almost twice the recording track width, in the second and subsequent erasing operations, erasing is performed by overlapping the previously erased track by 2/3 tracks. Therefore, as shown in FIG. 10 (b), the rotary erasing head FE leads the third rotating magnetic head HD3, but follows the second rotating magnetic head HD2. And the second track
On TR2, there is a problem that, of the information just recorded by the second rotating magnetic head HD2, information for 2/3 tracks where the rotating erase head FE overlaps is erased again.

In this case, the rotary erasing head on the cylindrical drum 2
By mounting the FE at a position one track width higher than the height A of the rotating magnetic head, the information just recorded will not be erased.
The difference h between the magnetic head and the rotating magnetic head is large, and the above-described disadvantage has occurred.

Accordingly, the present invention provides a magnetic recording apparatus in which four rotating magnetic heads and a rotating erasing head are mounted on a cylindrical drum, and has an erasing gap width almost twice the recording track width as conventionally used in general. It is an object of the present invention to provide a rotating magnetic head device that reduces costs by using a rotating erase head and that does not cause inconvenience in performance and manufacturing.

[Means for solving the problem]

In order to solve the above problems and achieve the above objectives,
In the rotating magnetic head device according to the present invention, the magnetic tape
に 対 し A total of four rotating magnetic heads using two sets of two rotating magnetic heads having different azimuth angles are arranged at equal intervals of 90 ° from each other on a cylindrical drum wound at an angle of more than one. In addition, in a rotary magnetic head device having a configuration in which a rotary erasing head is provided and each of the rotary magnetic heads is sequentially switched to operate, the angular position of the rotary magnetic head on which recording is performed first on the cylindrical drum is set to 0 as a reference. When ゜, the rotary erasing head is mounted at an angular position θ in the range of 180 ° ≦ θ ≦ 270 ° in the rotation direction of the rotary magnetic head.

[Action]

In the rotating magnetic head device according to the present invention configured as described above, since the information just recorded is not erased due to the overlapping of the rotating erasing head, the information is recorded on the track by the rotating magnetic head device. Before this, the information already recorded on the track can be surely erased. On the cylindrical drum, the height of the rotary erasing head relative to the rotary magnetic head is not more than one track width, so that there is no inconvenience during reproduction due to poor contact between the magnetic tape and the rotary magnetic head.

〔Example〕

1, 2, 3, and 4 show an example of the rotary magnetic head device according to the present invention. The same components as those of the rotary magnetic head device shown in FIG. 8 are denoted by the same reference numerals, and detailed description thereof will be omitted.

Two cylinders having different azimuth angles on a cylindrical drum 2
2 sets of rotating magnetic heads 2 sets of 4 rotating magnetic heads HD1, H
D2, HD3, and HD4 are mounted at the same height, keeping a 90-degree angle between them. The magnetic tape 1 is wound around the cylindrical drum 2 at an angle of approximately 270 °, and the magnetic tape 1 is run obliquely from top to bottom in the same direction F as the rotation direction R of the rotary magnetic head.

In performing recording, the rotary magnetic head unit that starts recording first is determined by a predetermined circuit in the magnetic recording apparatus. In the embodiment, the first rotary magnetic head HD is used.
Let 1 be a rotating magnetic head that performs recording first.

When the rotating magnetic head rotates 270 ° in the R direction after the first rotating magnetic head HD1 starts recording, a first track TR1 is formed, and the recording head is switched to the second rotating magnetic head HD2, Next, the second track TR2 is formed by rotating the rotary magnetic head by 270 °. At the same time, the third rotating magnetic head HD3 and the fourth rotating magnetic head H
By D4, the third track TR3 and the fourth track TR4
Are formed, and four recording tracks are formed while the rotary magnetic head rotates three times.

In the rotating magnetic head device configured as described above,
When the angular position of the first rotary magnetic head HD1 on the cylindrical drum 2 is set to 0 ° as a reference, the rotation direction R of the rotary magnetic head
The rotary erasing head FE is mounted at an angular position θ in a range represented by 180 ° ≦ θ ≦ 270 °. That is, on the cylindrical drum 2, the third
The rotary erase head FE is mounted between the rotary magnetic head HD3 and the fourth rotary magnetic head HD4. Actually, a third rotating magnetic head HD3 and a fourth rotating magnetic head HD4 are mounted at angular positions of 180 ° and 270 °, respectively, and a head base for fixing the head to the cylindrical drum 2 is provided. Takes a lot of space, so the rotary erase head
The range in which the FE can be mounted on the cylindrical drum 2 is further narrowed, and considering the balance of the entire rotating magnetic head, the rotating erasing head FE is located between the third rotating magnetic head HD3 and the fourth rotating magnetic head HD4. It is desirable to attach to the position of 225 ° which is the angular position.

Since a conventionally used rotary erase head FE is used, the gap width of the rotary erase head FE is almost twice the recording track width.

On the cylindrical drum 2, the gap heights of the four rotating magnetic heads HD1, HD2, HD3, and HD4 are the same, but the gap of the rotating erasing head FE is calculated by the equation (2) described above.
Is higher than the rotating magnetic head by the height h represented by For example, according to the 8 mm VTR standard, the recording track width Tp
Is 20.5 μm. Therefore, when the rotational erasing head FE is mounted at the point of θ = 225 °, the rotational erasing head FE is 17.1 μm.
It may be mounted at a position higher by μm, but in practice, a signal leaks slightly from the gap edge of the rotary erasing head FE.

A track formed by the rotary magnetic head device configured as described above will be described.

FIG. 1 (b) shows a track in a state where the rotary head is arranged as shown in FIG. 1 (a). At the moment when the first rotating magnetic head HD1 starts recording on the first track TR1, the rotating erasing head FE is arranged at a position of 225 ° on the first track TR1, and the first track TR1 and the first track TR1 are already located. The portion indicated by the diagonal lines of the track TR2 of No. 2 is deleted. Rotating magnetic heads HD2 and HD other than the first rotating magnetic head HD1
3. HD4 is arranged at the same height as the height A of the first rotating magnetic head HD1 on the cylindrical drum 2 at equal intervals, and the rotating erasing head FE is at a position higher by h than the height A of the rotating magnetic head. It is understood that there is.

Subsequently, the second rotation of the rotating magnetic head by 270 ° in the R direction
FIG. 2B shows the track in the state shown in FIG. At the moment when the second rotating magnetic head HD2 starts recording on the second track TR2, the rotating erasing head FE moves to the second track TR2.
Since it is located at 135 ° on TR2 and is located ahead of the second rotating magnetic head HD2, the second track T
There is no problem if the data is erased by overlapping on R2.

Then, the rotating magnetic head rotates 270 ° in the R direction.
FIG. 3B shows the track in the state shown in FIG. At the moment when the third rotating magnetic head HD3 starts recording on the third track TR3, the rotating erasing head FE moves to the third track TR3.
Since it is arranged at a position of 45 ° on TR3 and is located ahead of the third rotating magnetic head HD3, the third track T
There is no problem even if you erase by overlapping on R3.

Then, the rotating magnetic head is rotated 270 ° in the R direction.
FIG. 4B shows the track in the state shown in FIG. At the moment when the fourth rotating magnetic head HD4 starts recording on the fourth track TR4, the rotating erasing head FE is not in contact with the magnetic tape 1, but the erasing of the fourth track TR4 has already been completed.

Subsequently, when the rotating magnetic head rotates 270 ° in the R direction, the arrangement of the rotating head becomes the same as the state shown in FIG.

By repeating the above, recording is sequentially performed on a predetermined track. Therefore, the rotary erasing head always precedes the recording head, and the information of the track just recorded is not erased.

〔The invention's effect〕

As is apparent from the above description, according to the rotating magnetic head device of the present invention, the rotating erasing head always precedes the recording head. As a result, the data is not erased.

Therefore, it is not necessary to increase the height difference between the rotary magnetic head and the rotary erase head on the cylindrical drum, so that there is no inconvenience at the time of reproduction due to poor contact between the magnetic tape and the magnetic head. Further, the head does not come off from the field of view of the microscope for adjusting the height of the head in manufacturing.

Furthermore, the conventional recording track width of about 2
Since a rotating erase head having a double erase gap width is used, there is no need to design and manufacture a new rotating erase head, so that production costs can be reduced.

[Brief description of the drawings]

FIGS. 1, 2, 3, and 4 show the configuration of a rotary magnetic head device according to the present invention, and FIGS. 5 and 6 show a rotary erasing head on a cylindrical drum having two conventional rotary magnetic heads. FIG. 7 is a block diagram showing a conventional cylindrical drum having four rotating magnetic heads, FIG. 8 and FIG.
FIG. 10 and FIG. 10 are configuration diagrams in which a rotary erasing head is provided between the first rotary magnetic head and the second rotary magnetic head in FIG. In each figure, (a) is a configuration diagram showing a position of a head arranged on a cylindrical drum, and (b) is a configuration in which a track formed in the state of (a) is viewed from a base tape direction of a magnetic tape. FIG. 1 magnetic tape 2 cylindrical drum HD1 first rotating magnetic head HD2 second rotating magnetic head HD3 third rotating magnetic head HD4 fourth rotating magnetic head FE rotating Erase head

Claims (1)

(57) [Claims] 1. A cylindrical drum having four rotating magnetic heads and a rotating erasing head for simultaneously erasing two information tracks recorded by the rotating magnetic head, the magnetic tape having an angle of at least 270 ° or more. In the magnetic recording device wound in contact with the magnetic recording device, when the angular position on the cylindrical drum of the rotary magnetic head for recording first is set to 0 ° as a reference, the rotary erasing head is turned 180 ° toward the rotation direction of the rotary magnetic head. A rotating magnetic head device mounted at an angular position θ in a range of ≦ θ ≦ 270 °.