JPH1027324A - Recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable securing head contact performance without injuring head life by displacing a gap position to the position extremely enlarging contact force in a magnetic head part. SOLUTION: A magnetic head 1 is fixed to a head base 2, and the head base 2 is attached to an upper drum 4 by an attaching screw 5. At this point, the head base 2 is made freely rotatable around the screw 5. The head base 2 is rotation displaced by displacing a head attitude control member 3. The top 1b and the gap 1a of the magnetic head 1 coincide nearly with each other. When the head base 2 is rotate-displaced, the position of the top 1b isn't changed, and only the position of the gap 1a is displaced in the left direction. In such a manner, the center of rotation of the head base 2 is made coincide with the center of the top shape of the head 1 so that the position of the top of the magnetic head 1 and a projection amount from the upper drum 4 surface aren't changed by rotation displacing the base 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type recording system for recording and reproducing signals on a magnetic tape by using a magnetic head mounted on a rotary head device such as a VTR, a DAT and a data recorder for business use and a consumer use. It relates to a playback device.

[0002]

2. Description of the Related Art An example of a rotary head device used in a conventional recording / reproducing apparatus will be described with reference to FIGS. FIG. 8 is a perspective view of a rotary head device 21 used in a conventional recording / reproducing apparatus. In FIG. 8, a magnetic tape 17 supplied from a supply reel in a cassette passes through several guide posts (none of which are shown), and then passes through an entrance-side guide post 18 and is wound around the rotary head device 21 at a predetermined angle. After being turned, it is wound on a take-up reel (both not shown) in the cassette via the output side guide post 19. FIG. 9 is a sectional view of the rotary head device 21. In FIG. 9, 9 is a fixed lower drum, 8 is a shaft rotatably supported by the lower drum 9, 4 is an upper drum having substantially the same diameter as the lower drum 9 and rotating integrally with the shaft 8, 1 is a magnetic head, 2 is a head base for fixedly supporting the magnetic head 1, 5 is a mounting screw for fixing the head base to the upper drum 4, 7 is a motor for driving the upper drum 4 to rotate, 10 and 11 are between the rotating part and the fixed part. This is a rotary transformer for transmitting and receiving signals. As shown in FIG. 8, the magnetic head 1 protrudes by a predetermined amount from a projecting window 6 provided on the outer peripheral surface of the upper drum 4, and records a signal on a magnetic tape 17 wound around a rotary head device 21.
Regenerate.

[0003]

In recent years, magnetic tapes have become thinner due to an increase in recording capacity, and head contact performance and head life performance have been improved with all conventional thick and thin tapes. Need to secure. Since the upper drum 4 rotates at a high speed relative to the traveling speed of the magnetic tape 17 in the rotating head device 21, air flows between the upper drum 4 and the magnetic tape 17 to form an air layer. The thickness of the air layer is greatest near the entry position of the magnetic tape 17 and decreases as it goes toward the exit position. This air layer affects the contact (head contact) between the magnetic head 1 and the magnetic tape 17. The larger the air layer, the smaller the contact force between the magnetic head 1 and the magnetic tape 17. It is difficult to secure contact performance. Further, since the tape rigidity varies depending on the thickness of the magnetic tape, the contact state between the magnetic tape and the magnetic head also varies.

In a conventional rotary head device of a recording / reproducing apparatus, under the most severe conditions of head contact,
The protrusion amount of the magnetic head is increased so that the head contact performance can be ensured, and the contact force between the magnetic head and the magnetic tape is increased to ensure the head contact performance. However, under conditions where head contact is relatively easy to secure, for example, near the exit position where the air layer is small, the contact state between the magnetic head and the magnetic tape may be considered excessive. Excessive contact between the magnetic head and the magnetic tape causes a problem that the head life cannot be ensured because the magnetic head is worn away quickly. Further, when the amount of protrusion of the magnetic head is reduced in order to secure the head life performance, there is a problem that the head contact performance cannot be secured near a position where a large air layer enters, where it is difficult to secure the head contact performance.

An object of the present invention is to provide a rotary head device of a recording / reproducing apparatus which ensures a head contact performance without impairing a head life performance under all conditions in a system using a plurality of magnetic tapes having different tape rigidities. It is in.

[0006]

In order to solve the above-mentioned problems, a head attitude control member for displacing a magnetic head in a circumferential direction of a rotary head device, a head attitude control member driving circuit for driving the head attitude control member, and And a control circuit for driving and controlling the head attitude control member. The head attitude control member is controlled by the type of magnetic tape, the error rate of the reproduction output, or the reproduction envelope shape.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a recording / reproducing apparatus using an 8 mm cassette will be described below with reference to FIGS.

FIG. 1 is a partial view of the magnetic head mounting portion of the upper drum of the rotary head device of the present embodiment as viewed from the lower drum side, FIG. 2 is a sectional view of the rotary head device, and FIG. 3 shows the state of the magnetic head. FIG. 4 is an explanatory view showing a contact state between the magnetic head and the magnetic tape. 1 and 2, the magnetic head 1 is fixed to a head base 2, and the head base 2 is attached to an upper drum 4 by attaching screws 5. At this time, the head base 2 is freely rotatable about the mounting screw 5. Reference numeral 3 denotes a head attitude control member.
Has a structure that rotates and displaces. The head attitude control member 3
The member is not particularly limited as long as it is a member for displacing the head base 2, and as an example, a laminated piezoelectric element or the like capable of obtaining a displacement by applying a voltage can be cited. Next, the state of the magnetic head 1 due to the rotational displacement of the head base 2 will be described with reference to FIG. FIG. 3A shows that the vertex 1b of the magnetic head 1 and the gap 1a are almost coincident. When the head base 2 is rotationally displaced with respect to FIG.
As shown in FIG. 3B, the position of the vertex 1b does not change, and only the position of the gap 1a is displaced to the left (exit side). As described above, the rotational displacement of the head base 2 causes the position of the top of the magnetic head 1 and the upper drum 4
In order to prevent the amount of protrusion from the surface from changing, the center of rotation of the head base 2 is set to the tip shape (arc) of the magnetic head 1.
Must match the center of the

Next, the contact state between the magnetic head 1 and the magnetic tape 17 near the entry side where it is difficult to ensure the head contact performance will be described. FIG. 4 shows the rotary head device 2
FIG. 2 is an explanatory diagram of one magnetic head 1 viewed from a lower drum 9 direction. The magnetic head 1 projects slightly from the surface of the upper drum 4 and comes into contact with the magnetic tape 17. At this time, the magnetic head 1 moves at high speed from left to right in the drawing. In FIG. 4, reference numeral 1a denotes a gap portion for recording and reproducing signals, and 1b denotes a vertex of the most protruding portion of the magnetic head 1.

FIG. 4A shows a case where a thin tape having low rigidity is run. As shown in FIG. 4A, the magnetic tape 17 has low tape rigidity and is easily deformed.
The magnetic tape 17 is deformed so as to enclose the magnetic head 1. At this time, the tape tension acts in a direction to press the magnetic tape 17 against the magnetic head 1, but the magnetic tape 17 is deformed due to low rigidity, and the magnetic head 1 moves with the magnetic head 1 when moving rightward at high speed. Air flows in between the tape 17. Therefore, as shown in the figure, the contact force is small near the vertex 1b of the magnetic head 1 due to the occurrence of spacing (gap), and the contact force is greatest at the position shifted from the vertex 1b toward the retreating side (left side in the figure). Become. FIG. 4B shows a case where a thick tape having high rigidity is run. As shown in FIG. 4B, the magnetic tape 17 has a high tape rigidity and is hardly deformed, so that the magnetic tape 17 largely deforms with respect to the tip shape (arc) of the magnetic head 1. However, the tape tension acts in the direction of pressing the magnetic tape 17 against the drum side, so that the magnetic head 1 and the magnetic tape 17 are pressed.
And almost no air flows between them, and the contact force becomes highest near the vertex 1b. At this time, as shown in FIG. 4A, the contact force is small at a position shifted to the retreat side from the vertex 1b having the largest contact force of the thin tape.

FIG. 6 shows a reproduction envelope shape. The envelope is a shape of a reproduction output level synchronized with the rotation of the rotary head device 21. The reproduction envelope shape is often used as a criterion for judging the head contact performance. In a good head contact state, the reproduction envelope shape becomes a substantially rectangular shape as shown in FIG. On the other hand, when the head contact performance is degraded on the entry side, the left side (entrance side) as shown in FIG.
And the level is getting smaller.

Therefore, as shown in FIGS. 4A and 4B,
When the gap 1a and the vertex 1b of the magnetic head 1 are substantially the same, and when a thin tape is run, the contact force is small at the gap 1a, so that the approach side (left side) as shown in FIG. The head contact performance is degraded. In the case of thick tape, since the contact force is large at the gap 1a,
As shown in FIG. 6B, a good reproduction envelope shape is obtained. Therefore, in order to obtain a good envelope shape even with a thin tape, as shown in FIG. 4C, the head base 2 is rotationally displaced so that the position of the gap 1a is on the left side, and the position where the contact force is maximized is determined. The gaps 1a may be matched. When a thick tape is used, as shown in FIG.
Are substantially the same, a reproduction envelope shape as shown in FIG. 6B can be obtained.

The optimum deviation L between the gap 1a and the vertex 1b of the magnetic head 1 differs depending on the tape rigidity and the relative speed of the head and the tape. As the speed increases, the shift amount L also increases. For example, an 8 μm thick 8
In the case of a system using a millimeter tape and a relative speed of about 11 m / s, the optimum displacement L is about 50 μm.

The operation of the present invention will be described with reference to FIG. FIG. 5 is a block diagram of the recording / reproducing apparatus of the present invention. Reference numeral 12 denotes a cassette containing the magnetic tape 17, and reference numeral 3 denotes a head attitude control member for displacing the gap 1a of the magnetic head 1. 13 is the type of the magnetic tape 17 in the cassette 12,
Tape type discriminating means for discriminating the thickness is denoted by 15 a head attitude control member drive circuit for driving the head attitude control member, and 14 a control circuit for driving and controlling the head attitude control member 3.

In the recording / reproducing apparatus of the present invention, the cassette 12
Information such as the type and the tape thickness of the magnetic tape 17 in the inside is obtained by the tape type discriminating means 13, and from this information,
The head attitude control member 3 is driven and controlled by the control circuit 14 and the head attitude control member drive circuit 15, and the gap 1a of the magnetic head 1 is displaced.

Here, a method of discriminating the type of the tape is as follows.
A brief description will be given using a millimeter cassette as an example. FIG. 7 is a bottom view of the 8-mm cassette. In FIG. 7, a hole (recognition hole) is provided on the bottom surface of the 8 mm cassette so that the apparatus can recognize the opening and closing of the hole so that information on the cassette 12 can be obtained. In the cassette information, a standard for preventing erroneous erasure, a tape thickness, a tape type, and the like are defined, and the head attitude control member 3 is controlled by the tape thickness and tape type information. Here, the description has been made by taking the 8 mm cassette as an example, but most systems obtain the tape information through the recognition holes as in the case of the 8 mm cassette. As a method other than the recognition hole, there is a method in which an IC memory in which tape information is recorded in a cassette, such as a 6 mm digital cassette, is used, and the tape information is obtained by the IC memory.

As described above, in the first embodiment, since the position of the gap 1a of the magnetic head 1 is rotationally displaced to the position where the contact force is maximized, it is not necessary to increase the protrusion amount of the magnetic head 1. Therefore, the head contact performance can be secured without deteriorating the head life performance due to head wear.

Next, a second embodiment will be described. FIG.
0 is a block diagram of the recording / reproducing apparatus of the second embodiment.
Reference numeral 20 denotes an error rate measuring means for measuring an error rate from the reproduction output from the magnetic head 1. In the first embodiment, the gap position is changed according to the tape type information. However, in the recording / reproducing apparatus of the second embodiment, the magnetic head 1
The head attitude control member 3 is driven and controlled by the control circuit 14 and the head attitude control member drive circuit 15 so that the error rate of the reproduced output from the magnetic head 1 is minimized so that the gap 1a of the magnetic head 1 is reduced. It is configured to be displaced. With the above configuration, it is not necessary to increase the head protrusion amount as in the recording / reproducing apparatus of the first embodiment, so that both the head life performance and the head contact performance can be ensured.

In the recording / reproducing apparatus of the first embodiment, the head attitude control member is controlled by the information of the magnetic tape obtained by the recognition hole of the cassette. However, the information of the magnetic tape obtained by the recognition hole is controlled. Can only obtain information of a rough classification of a thin tape and a thick tape, and an MP tape and an ME tape. Therefore, the position of the gap 1a does not always coincide with the position at which the contact force has the maximum value. However, since the difference is small, there is no significant effect. However, the recording / reproducing apparatus of the second embodiment can more accurately match the position of the gap 1a with the position where the contact force is maximized. Can be ensured.

Next, a third embodiment will be described. FIG.
FIG. 1 is a block diagram of a recording / reproducing apparatus according to a third embodiment.
Reference numeral 21 denotes an envelope observing means for observing a reproduction envelope shape from the magnetic head 1, and 22 denotes a magnetic head 1 and a magnetic tape 17 based on the observation result of the envelope observing means 21.
This is an arithmetic circuit for converting the state into contact with the data. The recording / reproducing apparatus according to the third embodiment converts the contact state between the magnetic head 1 and the magnetic tape 17 according to the envelope shape so that the contact state becomes the best, that is, the reproduction envelope shape is as shown in FIG. Thus, the head attitude control member 3 is driven and controlled by the control circuit 14 and the head attitude control member drive circuit 15 so that the gap 1a of the magnetic head 1 is displaced so as to be substantially rectangular. With the above configuration, it is not necessary to increase the head protrusion amount as in the recording / reproducing apparatuses of the first and second embodiments, so that both the head life performance and the head contact performance can be secured. .

In the first, second and third embodiments, the present invention is applied to a recording / reproducing apparatus using an 8 mm tape. However, the present invention applies to all helical scan recording / reproducing using a rotary head device. It can be employed in the device.

[0022]

According to the present invention, the gap position is shifted to the position where the contact force is the largest in the magnetic head portion, so that the head contact performance can be ensured without impairing the head life performance.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a magnetic head mounting portion of an upper drum of a rotary head device according to an embodiment.

FIG. 2 is a sectional view of a rotary head device.

FIG. 3 is an explanatory diagram showing a state of a magnetic head.

FIG. 4 is an explanatory diagram showing a contact state between a magnetic head and a magnetic tape.

FIG. 5 is a block diagram of a recording / reproducing apparatus according to the first embodiment.

FIG. 6 is an explanatory diagram showing a reproduction envelope shape.

FIG. 7 is a plan view of an 8 mm cassette.

FIG. 8 is a perspective view of a rotary head device of a conventional recording / reproducing apparatus.

FIG. 9 is a sectional view of a rotary head device of a conventional recording / reproducing apparatus.

FIG. 10 is a block diagram of a recording and reproducing apparatus according to a second embodiment.

FIG. 11 is a block diagram of a recording and reproducing apparatus according to a third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic head, 2 ... Head base, 3 ... Head attitude control member, 4 ... Upper drum.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroaki Ono 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the multimedia system development headquarters of Hitachi, Ltd. (72) Inventor Nobuyuki Kaku Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa No.292 Inside Hitachi Multimedia Systems Development Division

Claims (4)

[Claims] 1. A recording / reproducing apparatus in which a magnetic tape is wound at a predetermined angle around a rotary head device having at least one magnetic head mounted thereon, and the magnetic head records and reproduces signals on and from the magnetic tape. A head attitude control member for displacing the head attitude control member in a circumferential direction of the rotary head device, a head attitude control member drive circuit for driving the head attitude control member, and a control circuit for driving and controlling the head attitude control member. A recording / reproducing apparatus characterized by the above-mentioned. 2. A head attitude control device according to claim 1, wherein said head type control means determines a type of a magnetic tape to be used, a head attitude control member for displacing said magnetic head in a circumferential direction of said rotary head device. A recording / reproducing apparatus comprising: a head attitude control member driving circuit for driving a member; and a control circuit for driving and controlling the head attitude control member based on a result of the discrimination by the tape type discriminating means. 3. An error rate measuring means for measuring an error rate from a reproduction signal from said magnetic head, a head attitude control member for displacing said magnetic head in a circumferential direction of said rotary head device, A head attitude control member drive circuit for driving the head attitude control member,
A recording / reproducing apparatus comprising: a control circuit for driving and controlling the head attitude control member based on a measurement result of the error rate measuring means. 4. The magnetic head according to claim 1, wherein an envelope observing means for observing a reproduction envelope shape from said magnetic head, an arithmetic circuit for calculating an observation result of said envelope shape into a magnetic head output, and A head attitude control member for displacing in the circumferential direction of the device,
A recording / reproducing apparatus, comprising: a head attitude control member drive circuit for driving the head attitude control member; and a control circuit for driving and controlling the head attitude control member based on a calculation result of the arithmetic circuit.