JPH0478016A - Head moving mechanism - Google Patents

Abstract

PURPOSE:To realize highly responsive and highly precise control by sticking a rotary head to an upper side drum through a laminated piezoelectric element, and supplying driving voltage to the laminated piezoelectric element. CONSTITUTION:The rotary head 7 is stuck to the upper side drum 1 through the laminated piezoelectric element 28, and by supplying the driving voltage to the laminated piezoelectric element 28, the laminated piezoelectric element 28 is extended and contracted, and the rotary head 7 is moved in the width direction of a track on a magnetic tape. Then, since the laminated piezoelectric element 28 is constructed so as to have high rigidity, the self-resonant frequency of a head moving mechanism is made higher, and even the fall of the self- resonant frequency due to the weight of a member like the rotary head 7, etc., is besides the question. Thus, the highly responsive and highly precise tracking control can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a seven-dom binning mechanism for displacing a rotary head on a rotary drum in the width direction of a track on a magnetic tape.

[Conventional technology]

A rotating head type magnetic recording/reproducing device uses a rotating head to form a recording track that is inclined with respect to the longitudinal direction of the magnetic tape to record and reproduce signals. Tracking control to enable follow-up scanning, and even when performing variable-speed playback at a tape running speed different from that during recording, to make it possible to obtain a playback signal with less guard hand noise. Tracking control is being performed.

As a means for performing the above-mentioned tracking control, there is a head moving mechanism that uses a piezoelectric element to displace the rotary head in the width direction of the recording trunk. FIG. 6 shows a rotary head drum that is equipped with a head moving mechanism and a detector that detects the height position of the rotary head, and that controls the height of the rotary head based on a detection signal.

A central cylindrical portion 4a formed on the lower drum 4 in a fixed state
Bearings 10 and 10' are installed at the top and bottom of the
is provided, and this pair of upper and lower hair rings 10.1
0' supports the shaft 11 fitted inside the central cylindrical portion 4a in the radial direction, and the shaft 11 is rotatably provided with respect to the lower drum 4. A motor rotor 12 is fixedly attached to a portion near the lower end of the shaft 11, while a disk 13 is fixedly attached to a portion near the upper end of the shaft 11.

An upper drum 1 is fixedly attached to the outer periphery of the disk 13, and a slip ring 14 is fixedly attached to the upper part of the upper drum 1.

A head moving mechanism consisting of a light emitting element 3, a rotary head 7 for recording and reproducing, and a bimorph type piezoelectric element 2 is fixedly attached to the lower part of the upper drum 1, and the head moving mechanism consists of a light emitting element 3, a rotary head 7 for recording and reproduction, and a bimorph type piezoelectric element 2. The drive 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 I on the rotating side in the direction of the rotation axis, while a cylindrical core 15 is attached to the central cylindrical portion 4a of the lower drum 4 on the stationary side. A stator side core 16 is attached in the direction of the rotation axis, and constitutes a rotation transformer. Therefore, the rotor-side core 15 and the stator-side core I6 are arranged to face each other, and the size of the gap between them is controlled with high precision. The recording signal is transmitted between the rotor-side core 15 and the stake-side core 16 for rotation and to the throat 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 onto the magnetic tape 8 which is spirally wound along the tape guide lead portion 17.

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

As mentioned above, the bimorph piezoelectric element 2 is attached to the upper drum 1.
The mounting is fixed at the bottom of the. Further, a light emitting element 3 is provided approximately at the center of the surface of the bimorph piezoelectric element 2 facing the upper drum 1, and a rotating head 7 is provided at the left end. On the other hand, the light receiving element 5 is held at a height opposite to 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. This light-receiving element 5 is equipped with two divided light-receiving sections 5a and 5b, and their respective outputs are input to a differential amplifier 33. As the bimorph piezoelectric element 2 is displaced in the ±Z force direction (indicated by arrows in the same figure), the output of the differential amplifier 33 changes in proportion to the amount of displacement as shown in FIG. Accordingly, the height of the rotating head 7 can be detected. Based on the output of the differential amplifier 33, a drive voltage is supplied to the bimorph piezoelectric element 2 to control the height of the rotary head 7, that is, to perform tracking control.

Next, while referring to the process diagrams in FIGS. 9(a) to (g),
The method for attaching the head moving mechanism to the upper drum 1 will be explained below.

After attaching the head core 7a to the head base 22 (FIG. 2(a)), winding 19 is applied to the head core 7a, and the board 2 is attached.
Paste 3 ((b) in the same figure).

In order to finish polish the tip of the hend core 7a of the rotating head 7 as the bed moving mechanism subassembly obtained in this way, it is attached to the polishing jig 24 dedicated to the head moving mechanism subassembly and polished with the polishing tape 9 (same as the head moving mechanism subassembly). Figure (C)). After finishing the final polishing, the bimorph piezoelectric element 2 and the light emitting element 3 are attached with high precision to the rotary head 7 as the head moving mechanism subassembly (FIGS. 3(d) and 3(e)). The head moving mechanism completed as described above is attached to the upper drum 1 with high precision ((f) and (g) in the same figure).

(Problems to be Solved by the Invention) However, in the conventional configuration described above, the bimorph piezoelectric element 2 does not have very high rigidity, so the weight of the light emitting element 3 lowers the self-resonance frequency of the head moving mechanism.
This has the problem that the responsiveness of tracking control deteriorates, making it impossible to perform highly accurate tracking. In particular, as the outer diameter of the upper drum 1 becomes larger and as the rotational speed of the upper drum 1 becomes faster, higher tracking performance is required. The influence of weight cannot be ignored.

(Means for Solving the Problems) In order to solve the above problems, the head moving mechanism of the present invention includes a rotary head drum consisting of a fixed lower drum and a rotating upper drum. The head moving mechanism displaces the rotary head in the width direction of a track on a magnetic tape by displacing the rotary head in the width direction of a track on a magnetic tape by displacing the rotary head in the width direction of a track on the magnetic tape by displacing the rotary head in the width direction of a track on the magnetic tape. It is characterized by the presence of

[Function] According to the above configuration, the rotary head is attached to the upper drum via the laminated piezoelectric element. By supplying a driving voltage to the laminated piezoelectric element, the laminated piezoelectric element expands and contracts, and the rotary head is displaced in the width direction of the track on the magnetic tape. Because it has a much more rigid structure compared to
The self-resonance frequency of the head moving mechanism becomes high, and a decrease in the self-resonance frequency due to the weight of members such as the rotating head does not become a problem, and highly responsive and highly accurate trunking control can be realized.

[Example] An example of the present invention will be described below based on FIGS. 1 to 5. Note that members having the same functions as those shown in the drawings of the conventional example are given the same reference numerals.

In the rotating head drum equipped with the head moving mechanism of this embodiment, as shown in FIG.
A pair of upper and lower hair rings 10 and 10'' are provided respectively, and the shaft 11 fitted inside the central cylinder portion 4a is supported in the radial direction by the pair of upper and lower hair rings 10 and 10''. A shaft 11 is rotatably provided to the shaft 1.A motor rotor 12 is fixedly attached near the lower end of the shaft 1.
A disk 13 is mounted and fixed near the upper end of the shaft 11. The upper drum 1 is fixedly attached to the outer periphery of this disk 13.

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 cylindrical core 15 is attached to the central cylindrical portion 4a of the lower drum 4 on the stationary side. A stator side core 16 is attached in the direction of the rotation axis, and constitutes a rotation transformer. Therefore, 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 controlled with high precision. Then, between the rotor side core I5 and the stator side core 16, a rotating hand door (described later) for recording and reproduction is provided.
The recording signal is transmitted to. 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. This tape guide lead part 17
Signals are recorded helically on the magnetic tape 8, which is spirally wound along the magnetic tape 8, by a rotating hend door.

The head moving mechanism of this embodiment is shown in Figures 1 and 2.
As shown in the exploded perspective view of the figure, a light emitting element 3 is attached to the upper drum 1 and emits light in the direction of the lower drum 4;
A lens holder 26 that holds a collimator lens 26a (shown separately) that converts the light emitted from the light emitting element 3 into parallel light, a head assembly 29 that includes a rotating head 7, and a hollow space that displaces the rotating head 7 up and down. A prism that holds a cylindrical laminated piezoelectric element 28 and a prism 27a (shown in a separate figure) that refracts the light emitted from the light emitting element 3 and passed through the hollow cylindrical portion of the laminated piezoelectric element 28 in a predetermined direction. It is mainly composed of a light receiving element 5 that is attached to the holder 27 and the lower drum 4 and has two light receiving sections 5a and 5b (shown in separate drawings) that receive light refracted by the prism 27a. . In the rotary head drum of this embodiment, only one light receiving element 5 is provided on the lower drum 4, but the above-mentioned rad-moving mechanism for the rotary head 7 and the like other than the light receiving element 5 is provided on the upper drum 1. There are a pair of channels facing each other at 180 degrees, and below, when it is necessary to distinguish between them, CH, A (channel A), CH, B
(Channel B).

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

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

As described above, the optical system includes the light emitting element 3 attached to the upper drum 1, the collimator lens 26a, and the prism 2.
7a, and a light receiving element 5 attached to the lower drum 4 and having two divided light receiving sections 5a and 5b.

The signal detection system includes sample and hold circuits 31a and 31 that 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.
b. Amplifiers 32a and 32b that amplify the signals sampled by the sample and hold circuits 31a and 31b; a differential amplifier 33 that differentially amplifies the detection signals amplified by the amplifiers 32a and 32b; and a switching pulse for the output of the differential amplifier 33. a changeover switch 35 that switches based on 37;
Based on the output of the differential amplifier 33, CHoA and CH,B
It is composed of CH, A and CH, B control circuits 34a and 34b that output drive voltages to the stacked piezoelectric elements 28 of CH9A and CH,B in order to control the height position of the rotating head 7.

In the above configuration, the light emitted from the light emitting element 3 is
It is converted into parallel light by the collimator lens 26a, passes through the hollow part of the laminated piezoelectric element 28, and passes through the prism 27a.
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 is sampled by sample and hold circuits 31a and 31b, respectively, according to a switching pulse 36 generated in synchronization with the timing when the head moving mechanism passes over the light receiving element 5 attached to the lower drum 4 due to 10 rotations of the upper drum. and the amplifier 32a.
After being amplified at 32b, the signal is input to the differential amplifier 33. Note that the amplification factors of the amplifiers 32a and 32b are determined based on the above difference when the head center of the rotary head 7 provided in the head assembly 29 is at the 0 position shown in the figure, that is, when the rotary head drum is assembled. dynamic amplifier 33
The output is adjusted so that it becomes O.

From this state, for example, from the CH, A control circuit 34a,
Assuming that a driving voltage is supplied to the H and A laminated piezoelectric elements 28, the laminated piezoelectric elements 28 contract, and the +Z force direction head assembly 29 shown in the figure is displaced, the prism 27a
Since the light refracted at the left side moves parallel to the left direction in the figure, the output of the light receiving section 5a on the left side becomes larger than the output of the light receiving section 5b, and the output of the differential amplifier 33 becomes a negative voltage depending on the amount of displacement. becomes. In this way, the height position of the rotary head 7 can be detected from the output of the differential amplifier 33. The relationship between the displacement amount of the rotary head 7 in the ±Z force direction and the output of the differential amplifier 33 is shown in FIG.

Differential amplifier 3 according to the amount of displacement in the ±Z force direction of the rotating head 7
The output of No. 3 is input by the changeover switch 35 to the CH, A control circuit 34 a or the CH, B control circuit 34 b.

That is, the changeover switch 35 is activated by the switching pulse 37 that is inverted in response to the switching pulse 36.
By switching, when the head moving mechanism of CH9A is placed above the light receiving element 5, the output of the differential amplifier 33 is input to the CH, A control circuit 34a, and the head moving mechanism of CH9B is placed above the light receiving element 5. When the output of the differential amplifier 33 is reached, 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, CHlA and C
CH, A and CH from H, B control circuits 34a and 34b,
A driving voltage is supplied to the laminated piezoelectric element 28 of B, thereby controlling the height positions of the rotary heads 7 of CH, A and CH, B, and highly accurate tracking control is performed.

As described above, the hollow cylindrical portion 28a of the laminated piezoelectric element 28 is used as the optical path for the light emitted from the light emitting element 3, instead of using the rotary head protruding window 1a as in the conventional case.
(FIG. 1) and because the light receiving element 5 of the lower drum 4 is attached using the hole 4b, the emitted light is neither blocked nor diffusely reflected by the displacement of the helad moving mechanism.

Furthermore, since the laminated piezoelectric element 28 has a highly rigid structure, the self-resonant frequency of the head moving mechanism becomes high, and a decrease in the self-resonant frequency of the head moving mechanism caused by an increase in the mass of the head assembly 29 and the prism holder 27 is also a problem. It is possible to realize highly responsive and highly accurate trunking control without causing any problems.

Next, the method of assembling the head moving mechanism according to the present invention will be explained using FIG. 1 again.

First, the light emitting element 3 is attached from above the upper drum 1. On the other hand, a laminated piezoelectric element 28 to which a lens holder 26 holding a collimator lens 26a and a prism holder 27 holding a prism 27a are attached is attached from below the upper drum 1 and fixed at the upper end. The relay board 25 is inserted and fixed to the terminals 38, 38, 39, and 39 of the light emitting element 3 and the laminated piezoelectric element 28 that protrude from the upper plane 30 of the relay board 25. Thereafter, the head assembly 29 equipped with the rotary hend door is attached with high precision to the brism head nodder 27, which has already been attached to the second drum 1. The light-receiving element 5 is fixedly attached from below the lower drum 4, and the relay board 25'' is inserted into the terminals 40, 40 of the light-receiving element 5 protruding from the reference plane A at the bottom of the lower drum 4. Note that the height position of the head assembly 29 is controlled by the vertical expansion and contraction of the laminated piezoelectric element 28, so that the outer circumference of the laminated piezoelectric element 28 does not come into contact with the hollow part of the upper drum 1. Be careful.

Next, regarding the method of assembling the head assembly 29,
This will be explained with reference to the process diagrams shown in FIGS. 5(a) to 5(c).

After attaching the head core 7a to the hend head 18 ((a) in the same figure), winding 19 is applied to the head core 7a, and the board 2
Paste 0 ((b) in the same figure).

To finish polishing the tip of the head core 7a of the thus obtained hent assembly face 29, go to.

The door assembly 29 is attached to the polishing jig 21, and polished with the polishing chip 19 (FIG. 3(C)). After finishing polishing,
As described above, it is attached with high precision to the prism holder 27, which is already attached to the upper drum 1.

By the way, the assembly process of the hend assembly 29 is the same as the assembly process of the head assembly of a conventional rotary head type magnetic recording/reproducing device that is not equipped with a head moving mechanism, so the assembly equipment etc. are not the same as those of the conventional one. This means that there is no need to introduce new expensive equipment. Further, according to the head moving mechanism of this embodiment, even if a head moving mechanism is introduced into the rotating head drum, the assembly process of the head assembly 29 will not be complicated, and the production efficiency as before can be maintained. can.

〔Effect of the invention〕

As described above, in the blade moving mechanism of the present invention, the rotating head is attached to the upper drum via the laminated piezoelectric element. By supplying a driving voltage to the laminated piezoelectric element, the laminated piezoelectric element expands and contracts, and the rotating head is displaced in the width direction of the track on the magnetic tape. Since the structure is much more rigid than that of the head moving mechanism, the self-resonance frequency of the head moving mechanism is high, and the reduction in the self-resonance frequency due to the weight of components such as the rotating head does not become a problem. This has the effect of realizing accurate tracking control. Therefore, the outer diameter of the upper drum is large;
Further, even when the rotational speed is high, high tracking performance can be obtained.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention. FIG. 1 is a partial sectional view showing the configuration of a rotating hent drum equipped with a head moving mechanism according to this embodiment. FIG. 2 is an exploded perspective view of the head moving mechanism. FIG. 3 is an explanatory diagram showing the configuration of the optical system and the configuration of the signal detection system of the head moving mechanism. FIG. 4 is a graph showing the relationship between the amount of displacement of the rotary head in the ±Z force direction and the output of the differential amplifier. FIGS. 5(a) to 5(C) are assembly process diagrams of the head assembly. 6 to 9 show conventional examples. FIG. 6 is a partial sectional view showing the configuration of a rotating hent drum equipped with a head moving mechanism. FIG. 7 is an explanatory diagram showing the configuration of the optical system of the head moving mechanism and the configuration of the signal detection system. FIG. 8 is a graph showing the relationship between the amount of displacement of the rotary head in the ±Z force direction and the output of the differential amplifier. FIGS. 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 parts, 7 is a rotary head, 8 is a magnetic tape, 26 is a lens holder 26a is a collimator lens, 27 is a collimator lens. Prism holder 27a is a prism,
28 is a laminated piezoelectric element, and 29 is a head assembly. Patent Applicant: Sharp Corporation Jl I Figure 142 Figure -〇Figure Differential F+ Towara Figure (a) Figure (b)

Claims (1)

[Claims] 1. In a rotary head drum consisting of a fixed lower drum and a rotating upper drum, the rotary head is attached to the upper drum via a piezoelectric element, and a driving voltage is supplied to the piezoelectric element. . A head moving mechanism for displacing the rotary head in the width direction of a track on a magnetic tape, characterized in that a laminated piezoelectric element is provided as the piezoelectric element.