JP2589859B2 - Head moving mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a head moving mechanism for displacing a rotary head on a rotary head drum in a width direction of a track on a magnetic tape.

[Conventional technology]

A rotating head magnetic recording / reproducing apparatus that forms a recording track inclined with respect to the longitudinal direction of a magnetic tape by a rotating head and records and reproduces a signal. In order to obtain a reproduction signal with a small guard band noise even when performing tracking control for enabling the following scanning on the upper side or performing variable speed reproduction at a tape running speed different from that during recording. Tracking control is being performed.

As a means for performing the tracking control, there is a head moving mechanism for displacing a rotary head in the width direction of a recording track by a piezoelectric element. FIG. 6 shows a rotary head drum that includes a head moving mechanism and a detector that detects the height position of the rotary head, and controls the height of the rotary head based on a detection signal.

Central cylindrical portion 4a formed on lower drum 4 in a fixed state
The upper and lower parts are provided with bearings 10 and 10 ', respectively, and the upper and lower pair of bearings 10 and 10' radially support the shaft 11 fitted inside the central cylindrical portion 4a. The shaft 11 is rotatably provided with respect to the lower drum 4. A motor rotor 12 is mounted and fixed near the lower end of the shaft 11, while a disk 13 is mounted and fixed near the upper end of the shaft 11. The upper drum 1 is attached and fixed to an outer peripheral portion of the disk 13, and a slip ring 14 is attached and fixed to an upper portion of the upper drum 1. A head moving mechanism including a light emitting element 3, a rotary head 7 for recording and reproduction, and a bimorph type piezoelectric element 2 is attached and fixed to a lower portion of the upper drum 1, and a voltage applied to the light emitting element 3 and driving of the bimorph type piezoelectric element 2 are provided. The voltage is supplied by the brush 6 via the slip ring 14.

A cylindrical rotor-side core 15 is attached to the hollow cylindrical portion of the upper drum 1 on the rotating side in the direction of the rotation axis, while a central cylindrical portion 4a of the lower drum 4 on the fixed side has a cylindrical shape. The stator-side core 16 is mounted in the direction of the rotation axis, and forms a rotary transformer. For this reason, the rotor-side core 15 and the stator-side core 16 are arranged to face each other, and the size of the gap between them is managed with high precision. Then, a recording signal is transmitted between the rotor-side core 15 and the stator-side core 16 to the rotary head 7 for recording and reproduction. Further, a tape guide lead portion 17 is provided on the outer peripheral portion of the lower drum 4 so as to have a predetermined inclination angle (lead angle) with respect to the reference plane A. A signal is helically recorded by the rotary head 7 on the magnetic tape 8 wound spirally along the tape guide lead portion 17.

FIG. 7 shows a schematic configuration of the optical system and the signal detection system of the head moving mechanism.

As described above, the bimorph piezoelectric element 2 is attached and fixed to the lower part of the upper drum 1. A light emitting element 3 is provided at a substantially central portion on a surface of the bimorph type piezoelectric element 2 facing the upper drum 1, and a rotary head 7 is provided at a left end. On the other hand, the light receiving element 5 is held at a height facing the light emitting element 3 in a section where the magnetic tape 8 and the rotary head 7 do not come into contact with each other. The light receiving element 5 is provided with two divided light receiving sections 5a and 5b, and respective outputs are input to the differential amplifier 33. With the displacement of the bimorph type piezoelectric element 2 in the ± Z direction (indicated by the arrow in the same figure), the output of the differential amplifier 33 changes in proportion to the displacement as shown in FIG. Thus, the height of the rotary head 7 can be detected. Then, based on the output of the differential amplifier 33, a driving voltage is supplied to the bimorph type piezoelectric element 2 to control the height of the rotary head 7, that is, to perform tracking control.

Next, a method of attaching the head moving mechanism to the upper drum 1 will be described with reference to FIGS. 9 (a) to 9 (g).

After attaching the head core 7a to the head base 22 (FIG. 9A), the winding 19 is applied to the head core 7a, and the substrate 23 is attached (FIG. 9B). In order to finish-polish the tip of the head core 7a of the rotary head 7 as the head moving mechanism subassembly obtained in this way, it is attached to a polishing jig 24 dedicated to the head moving mechanism subassembly.
Polishing is performed with a polishing tape 9 (FIG. 3C). After the finish polishing, the bimorph type piezoelectric element 2 and the light emitting element 3 are attached with high precision to the rotary head 7 as the head moving mechanism sub-assembly (FIG. 4D).
(E)). The head moving mechanism completed as described above is mounted on the upper drum 1 with high accuracy (FIGS. (F) and (g)).

[Problems to be solved by the invention]

However, in the above-described conventional configuration, the rigidity of the bimorph type piezoelectric element 2 is not so high, so that the self-resonant frequency of the head moving mechanism is reduced due to the weight of the light emitting element 3, and the responsiveness of tracking control is deteriorated. Tracking cannot be performed. In particular, as the outer diameter of the upper drum 1 increases and as the rotational speed of the upper drum 1 increases, higher tracking performance is required. However, under these conditions, the centrifugal force acts more, so that the light emitting element 3 The effect of the weight of the car cannot be ignored.

Further, in the above-described conventional configuration, the rotary head projecting window 1a is used as an optical path through which light emitted from the light emitting element 3 passes. Therefore, light emitted from the light emitting element 3 is
Depending on the displacement of the rotary head 7, there is also a problem that accurate head position detection cannot be performed due to being blocked or irregularly reflected by the rotary head projecting window 1a, and high-accuracy tracking control cannot be performed. I have.

[Means for solving the problem]

In order to solve the above-mentioned problem, a head moving mechanism of the present invention includes a rotating head mounted on a rotating head drum composed of a fixed lower drum and a rotating upper drum via a piezoelectric element. By supplying a driving voltage to the element, the rotary head is displaced in the width direction of the track on the magnetic tape, and a head moving mechanism that detects a displacement amount of the rotary head using a light emitting element and a light receiving element. While a laminated piezoelectric element having a hollow cylindrical portion inside as a piezoelectric element is provided,
The light emitting element and the light receiving element are provided on a rotary head drum such that light emitted from the light emitting element is received by the light receiving element via the hollow cylindrical portion of the laminated piezoelectric element. .

(Operation)

According to the above configuration, the rotary head is mounted on the upper drum via the multilayer piezoelectric element, and by supplying a driving voltage to the multilayer piezoelectric element, the multilayer piezoelectric element expands and contracts, and the rotary head becomes magnetic. It is displaced in the width direction of the track on the tape. Since the laminated piezoelectric element used here has a structure much higher in rigidity than, for example, a bimorph piezoelectric element, the self-resonant frequency of the head moving mechanism is increased, and the outer diameter of the upper drum is reduced. Even if the rotation speed of the upper drum is high or the rotation speed of the upper drum is high, the decrease in the self-resonance frequency due to the weight of the member such as the rotary head does not cause a problem, and highly accurate tracking control with high responsiveness can be realized.

In addition, according to the configuration, the hollow piezoelectric portion is formed in the multilayer piezoelectric element, and the light emitted from the light emitting element is received by the light receiving element via the hollow cylindrical portion inside the multilayer piezoelectric element. As described above, the light emitted from the light emitting element, as in the conventional configuration using the rotating head projecting window as an optical path through which the light emitted from the light emitting element passes,
Due to the displacement of the rotary head, there is no obstruction or irregular reflection at the rotary head projecting window. Accordingly, regardless of the displacement of the rotary head, accurate head displacement can always be detected, and highly accurate tracking control can be performed.

〔Example〕

One embodiment of the present invention will be described below with reference to FIGS. Members having the same functions as the members shown in the drawings of the conventional example are denoted by the same reference numerals.

In the rotary head drum provided with the head moving mechanism of the present embodiment, as shown in FIG. 1, upper and lower portions of a central cylindrical portion 4a formed on the lower drum 4 in a fixed state are provided with:
Bearings 10 ・ 10 ′ are provided, respectively, and the upper and lower pair of bearings 10 ・ 10 ′ allow the central cylindrical portion 4a
The shaft 11 inserted in the inside is supported in the radial direction, and the shaft 11 is rotatably provided with respect to the lower drum 4. A motor rotor 12 is mounted and fixed near the lower end of the shaft 11, while a disk 13 is mounted and fixed near the upper end of the shaft 11. The upper drum 1 is attached and fixed to an outer peripheral portion of the disk 13.

A rotor-side core 15 having a cylindrical shape is attached to the hollow cylindrical portion of the upper drum 1 on the rotating side in the rotation axis direction, while a cylindrical portion is mounted on the central cylindrical portion 4a of the lower drum 4 on the fixed side. The stator-side core 16 is mounted in the direction of the rotation axis, and forms a rotary transformer. For this reason, the rotor-side core 15 and the stator-side core 16 are arranged to face each other, and the size of the gap between them is managed with high precision. A recording signal is transmitted between the rotor-side core 15 and the stator-side core 16 to a recording / reproducing rotary head 7 (described later). Further, a tape guide lead portion 17 is provided on the outer peripheral portion of the lower drum 4 so as to have a predetermined inclination angle (lead angle) with respect to the reference plane A. A signal is helically recorded by the rotary head 7 on the magnetic tape 8 wound spirally along the tape guide lead portion 17.

The head moving mechanism of the present embodiment is shown in FIGS.
As shown in the exploded perspective view of the figure, a light emitting element 3 attached to the upper drum 1 and emitting light in the direction of the lower drum 4,
A lens holder 26 holding a collimator lens 26a (shown in another figure) for converting the light emitted from the light emitting element 3 into parallel light,
A head assembly 29 having a rotating head 7, a hollow cylindrical laminated piezoelectric element 28 for vertically displacing the rotating head 7,
A prism holder 27 holding a prism 27a (shown in another view) for refracting light emitted from the light emitting element 3 and passing through the hollow cylindrical portion 28a of the laminated piezoelectric element 28 in a predetermined direction, and the lower drum 4 Mounted on the above prism
Light-receiving parts 5a and 5b divided into two to receive the light refracted by 27a
(Shown in another figure). In the rotary head drum of the present embodiment, only one light receiving element 5 is provided on the lower drum 4. However, the head moving mechanism of the rotary head 7 excluding the light receiving element 5 has a 180 degree rotation on the upper drum 1. A pair is provided to face each other. Hereinafter, when it is necessary to distinguish them, they are referred to as CH.A (channel A) and CH.B (channel B).

The applied voltage of the light emitting element 3 and the driving voltage of the laminated piezoelectric element 28 are supplied by the brush 6 via the slip ring 14 (FIG. 1) fixed to the upper part of the upper drum 1.

Next, the configuration of the optical system and the configuration of the signal detection system of the head moving mechanism are shown in FIG. 3, and the operation thereof will be described.

As described above, the optical system includes the light emitting element 3 mounted on the upper drum 1, the collimator lens 26a, and the prism 27a.
And a two-part light receiving unit 5a attached to the lower drum 4.
· It is composed of the light receiving element 5 provided with 5b.

The signal detection system amplifies the signals sampled by the sample and hold circuits 31a and 31b, which sample the respective signals detected by the light receiving sections 5a and 5b of the light receiving element 5 based on the switching pulse 36, and the sample and hold circuits 31a and 31b. Amplifiers 32a and 32b, a differential amplifier 33 that differentially amplifies the detection signal amplified by the amplifiers 32a and 32b, a changeover switch 35 that switches the output of the differential amplifier 33 based on a switching pulse 37, and an output of the differential amplifier 33 Based on CH.A and
CH.A and CH.B control circuits 34a and 34b that output drive voltages to the stacked piezoelectric elements 28 of CH.A and CH.B to control the height position of the rotary head 7 of CH.B. You.

In the above configuration, the light emitted from the light emitting element 3 is converted into parallel light by the collimator lens 26a,
The light passes through the hollow cylindrical portion 28a of the laminated piezoelectric element 28, is refracted by the prism 27a, irradiates the light receiving element 5 attached to the lower drum 4, and is detected by the two divided light receiving sections 5a and 5b. The detection signal indicates that the head moving mechanism is attached to the lower drum 4 by the rotation of the upper drum 1.
In accordance with the switching pulse 36 generated in synchronization with the timing of passing through the above, the signals are sampled by the sample and hold circuits 31a and 31b, respectively, amplified by the amplifiers 32a and 32b, and input to the differential amplifier 33. The amplification factors of the amplifiers 32a and 32b are different from each other when the head sensor of the rotary head 7 provided in the head assembly 29 is at the position 0 shown in FIG. The output of the dynamic amplifier 33 is adjusted to be zero.

In this state, for example, a drive voltage is supplied from the CH.A control circuit 34a to the multilayer piezoelectric element 28 of CH.A, the multilayer piezoelectric element 28 contracts, and the head assembly moves in the + Z direction shown in the drawing.
If the beam 29 is displaced, the light refracted by the prism 27a moves in parallel in the left direction in the drawing, so that the output of the light receiving section 5a on the left becomes larger than the output of the light receiving section 5b, and the differential amplifier 33
Output becomes a negative voltage according to the displacement amount. Thus, the height position of the rotary head 7 can be detected from the output of the differential amplifier 33. FIG. 4 shows the relationship between the displacement amount of the rotary head 7 in the ± Z direction and the output of the differential amplifier 33.

A differential amplifier according to the displacement amount of the rotary head 7 in the ± Z direction
The output of 33 is switched by the changeover switch 35 to the CH.A control circuit 34.
a or is input to the CH.B control circuit 34b. That is, by switching the changeover switch 35 with a switching pulse 37 that is inverted according to the switching pulse 36,
When the CH.A head moving mechanism comes over the light receiving element 5, the output of the differential amplifier 33 is input to the CH.A control circuit 34a, and when the CH.B head moving mechanism comes over the light receiving element 5. The output of the differential amplifier 33 is input to the CH.B control circuit 34b. Then, according to the output of the differential amplifier 33, CH.A and
A drive voltage is supplied from the CH.B control circuits 34a and 34b to the CH.A and CH.B laminated piezoelectric elements 28, whereby the CH.A and CH.B
The height position of the rotary head 7 is controlled, and highly accurate tracking control is performed.

As described above, instead of using the rotating head protruding window 1a as an optical path through which light emitted from the light emitting element 3 passes, the hollow cylindrical portion 28a of the laminated piezoelectric element 28 (FIG. 1) and Mounting hole 4b for light receiving element 5 of lower drum 4
Therefore, the emitted light is not blocked or irregularly reflected by the displacement of the head moving mechanism.

Furthermore, since the laminated piezoelectric element 28 has a high rigidity structure, the self-resonant frequency of the head moving mechanism is increased, and the self-resonant frequency of the head moving mechanism is reduced due to an increase in the mass of the head assembly 29 and the prism holder 27. And high-accuracy tracking control with high responsiveness can be realized.

Next, a method of assembling the head moving mechanism according to the present invention will be described again with reference to FIG.

First, the light emitting element 3 is attached from above the upper drum 1. On the other hand, a lens holder 26 holding a collimator lens 26a and a prism holder 27 holding a prism 27a
Are attached from below the upper drum 1 and fixed at the upper end, and the light emitting element 3 protruding from the upper flat surface 30 of the upper drum 1 and the terminals 38, 38 of the multilayer piezoelectric element 28 are attached.・ Insert the relay board 25 into 39 and 39 and fix it. Thereafter, the head assembly 29 having the rotary head 7 is attached to the prism holder 27 already attached to the upper drum 1 with high accuracy. The light receiving element 5 is attached and fixed from below the lower drum 4, and the relay board 25 'is inserted and fixed to the terminals 40 of the light receiving element 5 protruding from the reference surface A below the lower drum 4. I do. Since the height position of the head assembly 29 is controlled by vertically expanding and contracting the multilayer piezoelectric element 28, care must be taken so that the outer peripheral portion of the multilayer piezoelectric element 28 does not contact the hollow portion of the upper drum 1. .

Next, regarding an assembling method of the head assembly 29,
This will be described with reference to FIGS. 5 (a) to 5 (c).

After attaching the head core 7a to the head base 18 (FIG. 7A), the winding 19 is applied to the head core 7a, and the substrate 20 is attached (FIG. 9B). In order to finish-polish the tip of the head core 7a of the head assembly 29 thus obtained, the head assembly 29 is attached to the polishing jig 21 and polished with the polishing tape 9 (FIG. 3 (c)). After the finish polishing, as described above, it is mounted on the prism holder 27 already mounted on the upper drum 1 with high accuracy.

By the way, since the assembling process of the head assembly 29 is the same as the assembling process of the head assembly of the conventional rotary head type magnetic recording / reproducing apparatus without the head moving mechanism, the conventional assembling apparatus is diverted. It is possible and there is no need to introduce new expensive equipment. Further, according to the head moving mechanism of the present embodiment, even if the head moving mechanism is introduced to the rotary head drum, the assembly process of the head assembly 29 is not complicated, and the same production efficiency can be maintained.

〔The invention's effect〕

As described above, the head moving mechanism of the present invention is provided with a laminated piezoelectric element having a hollow cylindrical portion inside as a piezoelectric element, while the light emitting element and the light receiving element are:
The light emitting element is provided on a rotating head drum such that light emitted from the light emitting element is received by a light receiving element via a hollow cylindrical portion of the laminated piezoelectric element.

Thus, the self-resonant frequency is not reduced due to the weight of the member such as the rotating head, and high-accuracy tracking control with high responsiveness can be realized. Even if the outer diameter of the upper drum is large, Even if it is fast, high tracking performance can be obtained.

Further, as in the conventional configuration using a rotating head protruding window as an optical path through which light emitted from the light emitting element passes, light emitted from the light emitting element is displaced by the rotating head.
Since there is no interruption or irregular reflection at the rotating head projecting window, accurate head displacement detection can always be performed regardless of the displacement of the rotating head, and as a result, highly accurate tracking control can be realized.

[Brief description of the drawings]

1 to 5 show one embodiment of the present invention. FIG. 1 is a partial cross-sectional view showing a configuration of a rotary head drum provided with a head moving mechanism of the present embodiment. FIG. 2 is an exploded perspective view of the head moving mechanism. FIG. 3 is an explanatory diagram showing a configuration of an optical system and a configuration of a signal detection system of the head moving mechanism. FIG. 4 is a graph showing the relationship between the displacement of the rotary head in the ± Z direction and the output of the differential amplifier. 5 (a) to 5 (c) are assembly process diagrams of the head assembly. 6 to 9 show a conventional example. FIG. 6 is a partial sectional view showing a configuration of a rotary head drum provided with a head moving mechanism. FIG. 7 is an explanatory diagram showing a configuration of an optical system and a configuration of a signal detection system of the head moving mechanism. FIG. 8 is a graph showing the relationship between the displacement of the rotary head in the ± Z direction and the output of the differential amplifier. 9 (a) to 9 (g) are assembly process diagrams of the head moving mechanism. 1 is an upper drum, 4 is a lower drum, 3 is a light emitting element, 5 is a light receiving element, 5a and 5b are light receiving sections, 7 is a rotating head, 8 is a magnetic tape, 26 is a lens holder, 26a is a collimator lens, 27 Is a prism holder, 27a is a prism, 28 is a laminated piezoelectric element, 28a is a hollow cylindrical portion, and 29 is a head assembly.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-287915 (JP, A) JP-A-2-230508 (JP, A) JP-A-3-192512 (JP, A) JP-A-3-302 173913 (JP, A) JP-A-3-150717 (JP, A) JP-A-3-113711 (JP, A) JP-A-60-147926 (JP, A) JP-A-60-109774 (JP, A)

Claims (1)

(57) [Claims] 1. A rotary head comprising a fixed lower drum and a rotating upper drum. A rotary head is mounted on an upper drum of the rotary head drum via a piezoelectric element, and a driving voltage is supplied to the piezoelectric element to thereby rotate the rotary head. A head moving mechanism for displacing a head in a width direction of a track on a magnetic tape and detecting a displacement amount of the rotary head using a light emitting element and a light receiving element, wherein a laminated type having a hollow cylindrical portion as the piezoelectric element therein While a piezoelectric element is provided,
The light emitting element and the light receiving element are provided on a rotary head drum such that light emitted from the light emitting element is received by the light receiving element via a hollow cylindrical portion of the laminated piezoelectric element. Head moving mechanism.