JPH0442419A - Rotary head cylinder device - Google Patents

Abstract

PURPOSE:To secure uniform contact pressure between a magnetic head and a magnetic tape extending over entire rotating phase by providing a groove part constituted at the outer peripheral cylindrical part of a rotary cylinder, and a groove shape varying means which varies the shape of the groove part corresponding to the rotating phase of the magnetic head. CONSTITUTION:The rotary cylinder 20 is formed in such structure that plural cylindrical members 24 and groove shape varying members 23 are laminated. The groove shape varying member 23 is made of a piezoelectric ceramic element, and is polarized and oriented so as to control the width in a rotating direction by applying a voltage by using the voltage supply means of a slip ring, etc., and the groove part 21 is composed in such a manner that the radius in the outer peripheral cylindrical plane of the groove shape varying means 23 is formed less than that of the outer peripheral cylindrical plane of the rotary cylinder 20. The shape of the groove part 21 can be varied corresponding to the rotating phase of the magnetic head 2. Thereby, since the thickness of an air layer 5 can be uniformalized extending over from the neighborhood of a scan start phase 16 to the neighborhood of a scan end phase 17, the contact pressure of the magnetic tape 4 on the magnetic head 2 can always be uniformalized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotary head cylinder device for magnetic recording and reproduction used in video tape recorders, digital audio tape recorders, and the like.

2. Description of the Related Art In recent years, video tape recorders, digital audio recorders, and the like have been required to have high image and sound quality. Along with this, there is a demand for more advanced basic elemental technology for recording and reproducing magnetic tape using the magnetic head cylinder method.

In particular, the flying height of the magnetic tape from the rotating cylinder is large near the scan start phase and small near the scan end phase, so the contact pressure between the magnetic tape and the magnetic head is insufficient near the scan start phase, resulting in incomplete signal exchange. Furthermore, since the contact pressure is too high near the scanning end phase, there are problems such as premature wear of the magnetic head, damage to the magnetic tape, and increased load on the capstan motor to drive the magnetic tape. In order to solve this problem, it is necessary to maintain the flying height of the magnetic tape from the rotating cylinder at a constant amount from the scan start phase to the scan end phase.

FIG. 8 for explaining a conventional rotary head cylinder device is a side sectional view of the conventional rotary head cylinder device, and FIG. 9 is a view taken along the line LL in FIG. 8 in the direction of arrow a.

In the figure, a magnetic head 2 is attached to the lower end surface of a rotary cylinder 1 in the axial direction. The rotating cylinder 1 is disposed coaxially with and facing the fixed cylinder 3. A groove 6 is provided in the outer cylindrical portion of the rotary cylinder 1 . The magnetic tape 4 is guided by an entry post 8 and an exit post 9, and is wound around the rotary cylinder 1 and the fixed cylinder 3 from a scan start phase 16 to a scan end phase 17. The fixed cylinder 3 is provided with a lead 15 which is a stepped portion for guiding the magnetic tape 4. The rotating cylinder 1 and the rotating shaft 19 are integrally fixed by a disk 7. A motor 18 for rotationally driving the rotary cylinder 1 is fixed to the rotary shaft 19 .

Further, in order to electrically connect the magnetic head 2 and a signal processing circuit (not shown), a rotor core 13 fixed to the disk 7 and rotating integrally with the rotating cylinder 1, and a stator core fixed to the fixed cylinder 3 are provided. 14 are arranged facing each other to form a rotary transformer. A pulse generator 25 that generates a signal according to the rotational phase of the rotary cylinder 1 is provided in the motor 18 . Further, an air layer 5 is formed between the magnetic tape 4 and the rotating cylinder 1.

The operation of the rotary head cylinder device configured as described above will be explained below.

The magnetic tape 4 is guided by an entry post 8 and an exit post 9, is wound around the rotary cylinder 1 and the fixed cylinder 3, and runs in the direction of arrow A. The rotating cylinder 1, with the magnetic tape 4 wound thereon, rotates in the direction of arrow B while being controlled one rotation based on the signal from the pulse generator 25, but since its peripheral speed is different from the running speed of the magnetic tape 4, the magnetic tape 4 is The head 2 scans the magnetic tape 4 relatively. That is, as the rotary cylinder 1 rotates, it comes into contact with the magnetic tape 4 in the scanning start phase 16 and starts scanning the magnetic tape 4.

When the rotary cylinder 1 further rotates by an angle θ, it separates from the magnetic tape 4 at a scan end phase 17, completing one scan. While repeating the above operations, the magnetic head 2 scans the magnetic tape 4 one after another.

Problems to be Solved by the Invention However, in the conventional configuration described above, the air near the outer cylindrical surface of the rotating cylinder is drawn in due to the effect of the viscosity of the air, so the air layer 5 is thick near the scan start phase 16, and the air layer 5 is thick near the scan start phase 16. 17. For this reason, the contact pressure of the magnetic tape 4 to the magnetic head 2 reaches the scan start phase 1.
It is low near phase 6 and becomes high near scan end phase 17.

As a result, the exchange of magnetic signals between the magnetic head 2 and the magnetic tape 4 tends to be incomplete near the scan start phase 16. Furthermore, if the tension of the magnetic tape 4 is increased in order to ensure the contact pressure near the scan start phase 16, the air layer 5 becomes too thin (too thin) near the scan end phase 17.
The magnetic tape 4 may be damaged due to contact with the rotating cylinder 1 near the rotating cylinder 1, the contact pressure between the magnetic tape and the magnetic head 2 may be too high, causing the magnetic head 2 to wear out quickly, and the driving load on the magnetic tape 4 may increase. I had an issue.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a rotary head cylinder device that can ensure uniform contact pressure between a magnetic head and a magnetic tape over all rotational phases from the scan start phase to the scan end phase. do.

Means for Solving the Problems The technical means of the present invention for solving the problems described above includes a groove formed in the outer cylindrical part of the rotating cylinder, and a groove whose shape changes according to the rotational phase of the magnetic head. This is because the shape changing means is provided.

action The effects of the technical means of the present invention are as follows.

That is, by providing the groove formed in the outer cylindrical portion of the rotating cylinder as described above and the groove shape variable means that changes the shape of the groove according to the rotational phase of the magnetic head, the thickness of the air layer can be scanned. Since it is uniform from the vicinity of the start phase to the vicinity of the scan end phase, the contact pressure of the magnetic tape to the magnetic head is also always uniform, making it possible to realize good transmission and reception of magnetic signals. In addition, the magnetic tape does not hit the rotating cylinder even near the scanning end phase, and the contact pressure between the magnetic head and the magnetic tape does not need to be unnecessarily high.
It is possible to prevent damage to the magnetic tape and an increase in the driving load of the magnetic tape, and it is also possible to extend the life of the magnetic head.

EXAMPLE Hereinafter, an example of the rotary head cylinder device of the present invention will be described with reference to the drawings.

FIG. 1 is a side cross-sectional view of a first embodiment of the rotary head cylinder device of the present invention, and FIG. 2 is a cross-sectional view taken along the line JJ in FIG. 1 in the direction of arrow a.

In these figures, the same parts as in the conventional example are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, the rotating cylinder 20 has a laminated structure of a plurality of cylindrical members 24 and a variable groove shape member 23. The variable groove shape member 23 is a piezoelectric ceramic element tank, and is polarized and oriented so that its thickness in the rotation axis direction increases or decreases by applying a voltage using a voltage supply means (not shown) such as a slip ring. , provided in the rotating cylinder 20. The groove portion 21 is formed by making the radius of the outer cylindrical surface of the variable groove shape member 23 smaller than the radius of the outer cylindrical surface of the rotating cylinder 20 . The other configurations are the same as the conventional example.

The operation of the rotary head cylinder device configured as described above will be explained below.

As shown in the figure, the magnetic tape 4 is wound around a rotating cylinder 20 and a fixed cylinder 3 by a magnetic tape loading means (not shown), and attached to a magnetic head 2 attached to the rotating cylinder 20.

The magnetic tape 4 is running in the direction of arrow A.

The rotating cylinder 20 rotates in the direction of arrow B with the magnetic tape 4 wound around it, but since the circumferential speed of the rotating cylinder 20 is different from the running speed of the magnetic tape 4, the magnetic head 2 scans the magnetic tape 4 relatively. do.

As the rotary cylinder 20 rotates, the magnetic head 2 comes into contact with the magnetic tape 4 at a scan start phase 16 and starts scanning. When the rotary cylinder 20 further rotates by an angle θ, the magnetic head 2 separates from the magnetic tape 4 at a scan end phase 17, completing one scan. While repeating the above operations, the magnetic head 2 scans the magnetic tape 4 one after another.

Here, based on the output signal of the pulse generator 25, a voltage corresponding to the rotational phase of the magnetic helad 2 is applied to the variable groove shape member 23, so that the thickness thereof is gradually changed to become thinner. Therefore, the width of the groove 21 becomes wider in the vicinity of the scan start phase 16.
The effect of air viscosity becomes smaller near the air layer 5
is formed thinly, but as the groove 21 becomes narrower toward the scanning end phase 17, the air existing in the groove 21 is pushed out and makes the magnetic tape 4 levitate.
The thickness can be kept uniform over all rotational phases up to near the scan end phase 17.

As described above, the groove 21 formed in the outer cylindrical portion of the rotary cylinder 20 and the groove 21 formed in the outer cylindrical portion of the rotary cylinder 20 and
1, the thickness of the air layer 5 becomes uniform over all rotational phases of the magnetic head.
The contact pressure is always uniform, and it is possible to realize good transmission and reception of magnetic signals.

In addition, the contact pressure between the magnetic head 2 and the magnetic tape 4, which the magnetic tape 4 makes against the rotary cylinder 1 even near the scanning end phase 17, is not required to be unnecessarily high, so that the magnetic tape 4 is not damaged or the magnetic tape 4 is damaged. An increase in driving load can be prevented, and the life of the magnetic head 2 can also be extended.

In this embodiment, the variable groove shape member 23 is made of a piezoelectric ceramic element tank, but as long as its thickness in the direction of the rotation axis can be varied and controlled, other organic piezoelectric materials or shape memory material may be used. An alloy or the like may be used, and the material and structure thereof are not limited.

Next, a second embodiment of the rotary head cylinder device of the present invention will be described with reference to the drawings.

FIG. 3 is a side sectional view of the rotary head cylinder device in the second embodiment. Moreover, FIG. 4 is an enlarged view of part 0 in FIG. 3. FIG. 5 is a cross-sectional view taken along arrow a in FIG. 3.

In these figures, the same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

The rotating cylinder 30 includes a plurality of cylindrical members 34 and spacers 35
It has a laminated structure with. The variable groove shape member 33 has a ring shape made up of a plurality of arc-shaped piezoelectric ceramic elements, and is attached to the outer peripheral surface of the spacer 35, but is not fixed to the cylindrical member 34. A groove portion 31 is formed in the outer peripheral cylindrical portion of the rotating cylinder 30 by a plurality of cylindrical members 34 and a variable groove shape member 33. The variable groove shape member 33 is polarized and oriented so that the radius of its outer cylindrical surface increases or decreases by applying a voltage using a voltage supply means (not shown) such as a slip ring. The other configurations are the same as the first embodiment.

The operation of the rotary head cylinder device configured as described above will be explained below.

As shown in the figure, the magnetic tape 4 is running in the direction of arrow A. The rotating cylinder 30 rotates in the direction of arrow B with the magnetic tape 4 wound around it, but since the circumferential speed of the rotating cylinder 30 is different from the running speed of the magnetic tape 4, the magnetic head 2 scans the magnetic tape 4 relatively. do.

Here, based on the output signal of the pulse generator 25, a voltage corresponding to the rotational phase of the magnetic head 2 is applied to the variable groove shape member 33, thereby changing the depth so that it gradually becomes shallower. Therefore, the groove 31 becomes deeper in the vicinity of the scan start phase 16, so the effect of air viscosity becomes smaller in the vicinity of the scan start phase 16, and the air layer 5 is formed thin, but the groove 31 becomes deeper toward the scan end phase 17. As the groove becomes shallower, the air existing in the groove 31 is pushed out and causes the magnetic tape 4 to float, so that the thickness of the air layer 5 can be kept uniform throughout the pre-rotation phase up to the vicinity of the scan end phase 17. Other operations are the same as in the first embodiment.

As described above, the groove portion 31 formed on the outer cylindrical portion of the rotary cylinder 30 and the groove portion 31 formed on the outer circumferential cylindrical portion of the rotary cylinder 30 and the groove portion depending on the rotational phase of the magnetic head. ! l
By providing the variable groove shape member 33 that changes the depth of the groove 531, the thickness of the air layer 5 becomes uniform over all rotational phases of the magnetic head, so that the contact pressure of the magnetic tape 4 to the magnetic head 2 is reduced. The magnetic field is always uniform, and it is possible to realize good transmission and reception of magnetic signals.

Furthermore, the magnetic tape 4 does not come into contact with the rotating cylinder 1 even near the scanning end phase 17, and the contact pressure between the magnetic head 2 and the magnetic tape 4 does not need to be unnecessarily high. can prevent an increase in drive load,
The life of the magnetic head 2 can also be extended.

In this embodiment, the variable groove shape member 33 is made of a piezoelectric ceramic element, but as long as the depth of the groove 31 is variable and controllable, other organic piezoelectric materials or shape memory alloys may be used. may be used, and the material and structure are not limited. For example, it is obvious that the variable groove shape member 33 may be made of a shape memory alloy that changes the shape of the groove portion 31 into a V shape, an arc shape, or the like.

Furthermore, the shape of the groove 31 may be changed by integrally forming the rotary cylinder 30 including the groove 31 with a shape memory alloy.

Furthermore, in this embodiment, as shown in the arrow view of FIG. 5, the variable groove shape member 33 is formed into a ring shape composed of a plurality of arc-shaped piezoelectric ceramic elements, so that the variable groove shape member 33 can be attached. As shown in the perspective view of FIG. 6 and the side sectional view of FIG. If the film 36 is deformed by the groove shape variable member 37, the groove shape variable member 37 can be constructed by separating a plurality of members as shown in FIG. The mass can be reduced, which has a significant effect on cost reduction and weight reduction.

Effects of the Invention As described above, according to the present invention, a rotary cylinder is provided with a groove formed in the outer cylindrical portion and a groove shape variable member that changes the shape of the groove in accordance with the rotational phase of the magnetic head. As a result, the thickness of the air layer formed between the rotating cylinder and the magnetic tape becomes uniform from the vicinity of the scan start phase to the vicinity of the scan end phase, so the contact pressure of the magnetic tape to the magnetic head is always uniform, resulting in good performance. This makes it possible to exchange magnetic signals.

In addition, the magnetic tape does not hit the rotating cylinder even near the end of the scan phase, and the contact pressure between the magnetic head and the magnetic tape does not need to be unnecessarily high, which prevents damage to the magnetic tape and an increase in the drive load on the magnetic tape. This can also extend the life of the magnetic head.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a rotary head cylinder device according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the J--J cross section in FIG. 1 in the same embodiment, and FIG. Second invention
A side sectional view of a rotating head cylinder device in an embodiment of
FIG. 4 is an enlarged view of part 0 in FIG. 3, FIG.
The figure shows a rotary head cylinder in another embodiment of the invention. 2...Magnetic head, 3...Fixed cylinder,
4...Magnetic tape, 5...Air layer, 16.
... Scanning start phase, 17... Scanning end phase,
20...Rotating cylinder, 21...Groove portion, 2
3... Groove shape variable member, 24... Cylindrical member, 2
5...Pulse generator. Name of agent: Patent attorney Shigetaka Awano 1 person W 8〈Ai Haboro■

Claims (1)

[Scope of Claims] A fixed cylinder that guides a tape-shaped recording medium, a head that sends and receives signals to and from the tape-shaped medium, and a rotary cylinder that is disposed coaxially facing the fixed cylinder and to which the head is attached. A rotary head cylinder device comprising: a groove formed in an outer cylindrical portion of the rotary cylinder; and a groove shape variable means for changing the shape of the groove in accordance with a rotational phase of the head.