JPH04192109A - Transducer device for converting information signal and information signal recording and reproducing device using this transducer device - Google Patents

Abstract

PURPOSE:To allow high-accuracy tracking by providing a function to finely move a transducer. CONSTITUTION:Detecting electrodes 10, 13 and driving electrodes 11, 14 are successively and respectively disposed form the free end mounted with the transducer 26 on the outside surface of a 1st mechano-electro conversion element 3 and on the imide surface of a 1st mechano-electro conversion element 4. Namely, these electrodes are preferably provided near the 2nd mechano-electro conversion element 16 or right above the elemen 16 in ordre for the vibration of the 2nd mechano-electro conversion element 16 and the displacement quantity of the transducer 26 to be sensibly detected. Further, common electrodes 12, 15 are formed as patterns on the inside surface of the 1st mechano-electro conversion element 3 facing the 1st mechano-electro conversion element 4 and the outside surface of the 1st mechano-electro conversion element over the etire surface thereof. The high-accuracy tracking is executed by adding the functions to finely move the transducer 26 in such a manner.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a video tape recorder (hereinafter referred to as VTR).
The present invention relates to an information conversion transducer suitable for use in information signal recording and reproducing devices such as hard disk drives (hereinafter referred to as HDDs), particularly magnetic recording and reproducing devices, and an information signal recording and reproducing device using the same. .

[Summary of the invention]

The present invention provides a method for fixing a pair of first mechanical-electrical conversion elements to a substrate with a predetermined interval, and connecting the free ends of these elements with a second mechanical-electrical conversion element. - fixing a transducer for information signal conversion to at least one free end of the electrical transducer;
A transducer device for information signal conversion, in which a detection electrode is provided directly above or in the vicinity of a mechanical-electrical conversion element, a drive electrode is provided in another part, and a common electrode is provided on the other surface, and this transducer device the information signal converting transducer is mounted, the detecting electrode detects coarse and fine movement displacement of the information signal converting transducer during reproduction, and the detected signal is applied to a first mechanical-electrical converting element to convert the information signal converting transducer. This is an information signal recording and reproducing device that controls fine movement displacement and scans the recording track as faithfully as possible.

[Conventional technology]

Conventional information signal recording and reproducing devices (hereinafter simply referred to as "recording and reproducing devices"), such as rotating magnetic head type VTRs, include:
A magnetic head is supported by a mechanical-electrical transducer such as a piezoelectric bimorph, and a control signal is applied to the mechanical-electrical transducer so that the magnetic head scans the magnetic track as faithfully as possible during reproduction. Some models employ an auto-tracking method that controls the

Furthermore, HDDs use a flying head that supports a magnetic head with a bimorph. During playback, this flying head is roughly moved by a voice coil motor (hereinafter referred to as "coarse movement"), and a control signal is applied to the bimorph. Some devices employ an auto-tracking method in which the magnetic track is scanned as faithfully as possible by making minute movements (hereinafter referred to as "fine movements").

However, in such a recording/reproducing device, the magnetic track width is wide, ranging from several 10 μm to 10 μm for the number of pages, and the number of magnetic tracks per pair is therefore a recording density of several hundred to several hundred. The above-mentioned auto-tracking method was also effective in a recording/reproducing device having a recording density of this level.

However, in high-density recording/reproduction devices where the magnetic track width is 10 μm or less or the number of magnetic tracks per pair is 1000 or more, the conventional auto-tracking method described above takes time to improve tracking accuracy and access time. Problems such as this arise. Further, the above-mentioned tracking method in the HDD has a large structure, and therefore has drawbacks such as long access time.

[Problem to be solved by the invention]

Therefore, in the present invention, a transducer device for converting information signals (hereinafter simply referred to as "transducer device") can reproduce even information signals recorded at high density as faithfully as possible.
The object of the present invention is to obtain a recording/reproducing device using the same.

[Means to solve the problem]

Therefore, the present invention supports an information signal conversion transducer (hereinafter simply referred to as "transducer") with two types of mechanical-electrical conversion elements, and supports the transducer with one mechanical-electrical conversion element. It is configured and controlled so that coarse movement is made by one element, and fine movement is made by the other mechanical-electric conversion element.

[For production]

Therefore, according to the present invention, even an information signal recorded at high density can be scanned finely, and a good reproduced information signal can be obtained.

〔Example〕

Hereinafter, a transducer device of the present invention and a recording/reproducing device using the same will be explained using the drawings.

FIG. 1 shows an embodiment of the transducer device of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a sectional view taken along line L-X2 in FIG.

First, its configuration will be explained. 1 is mounting hole 2
This is a rectangular parallelepiped base having a through hole, and substrates 5 and 6 having reference surfaces 5a and 6a are attached to the inner surface thereof with a predetermined distance therebetween. One end of the first mechanical-electrical conversion elements 3 and 4 is adhesively fixed to each of the reference surfaces 5a and 6a, and a second mechanical-electrical conversion element 16 is fixed between the other free ends thereof. are connected via a reinforcing plate 19 made of a material such as ceramics, and are bonded and fixed to each other.

In this embodiment, the first mechanical-electric conversion elements 3 and 4 have a so-called structure in which two piezoelectric plates that expand and contract in the length direction are bonded together, and when one expands, the other contracts, causing bending displacement as a whole. It is made up of bimorphs. Such a bimorph has a large displacement and responds at a low response frequency of several KHz. The shape of these elements was made into a trapezoid so as to have good response characteristics.

Further, the second mechanical-electric conversion element 16 has a structure of a laminated piezoelectric material in which several dozen or more ceramic piezoelectric materials each having a thickness of about several tens of micrometers are laminated. In this embodiment, for convenience, five piezoelectric bodies 21 to 25 are shown. As shown in the figure, the actual internal structure is such that electrode films are embedded in layers at intervals of several tens of micrometers inside the piezoelectric crystal and are connected alternately, and are drawn out to the outside as electrodes 17 and 18. ing. This second mechanical-electric conversion element 16 expands and contracts in the thickness direction of each of the electrodes 17 and 18 by applying a voltage to them, that is, utilizes the piezoelectric longitudinal effect.

Features include: 1) Can be made ultra-small 2) Displacement of several μm occurs when low voltage is applied 3) Number of 10
High-speed response can be obtained even when driven at KHz; 4) Positioning resolution is 0.01 μm, so positioning accuracy is high.

A transducer 26 is adhesively fixed to the surface of the free end of the first mechanical-electric conversion element 3 . In this embodiment, a magnetic head is illustrated as the transducer 26. 27-29
is the lead wire of the coil wound around the magnetic head.

A plurality of transducers can be adhesively fixed to the surface of the free end of the first mechanical-electrical transducer 3 by an information signal recording/reproducing method, and a plurality of transducers can be adhesively fixed to the surface of the free end of the first mechanical-electrical transducer 4. Adhesive fixation can be made both on the end surfaces and also on the free end surfaces of both first mechano-electrical transducer elements 3 and 4.

The outer surface of the first mechanical-electrical transducer 3 and the inner surface of the first mechanical-electrical transducer 4 are sequentially provided with sensing electrodes 10 and 13 and a driving electrode, respectively, from the free end where the transducer 26 is attached. Electrodes 11 and 14 were arranged.

That is, it is placed near the second mechanical-electrical transducer 16 so that vibrations of the second mechanical-electrical transducer 16 and displacement of the transducer 26 can be easily detected. Preferably, it is provided directly above the second mechanical-electric conversion element I6. Further, common electrodes 12 and 15 are formed on the inner surface of the first mechanical-electrical transducer 3 facing the first mechanical-electrical transducer 4 and on the outer surface of the first mechanical-electrical transducer in a pattern as shown in the figure. It is formed of.

Reference numerals 7 and 8 are single lead wire passing grooves provided in the center portions of the substrates 5 and 6, and 9 is a lead wire passing hole.

A terminal board 30 is adhesively fixed to the upper surface of the base 1, and each electrode pattern is formed on this. That is, the lead wires 27 to 29 of the transducer 26 are connected to the electrodes 39 to
41, lead wires from the detection electrode 10, drive electrode 11, and common electrode 12 of the first mechanical-electric conversion element 3 are connected to the electrode 31.
33, and the lead wires of the detection electrode 13, drive electrode 14 and common electrode 15 of the first mechano-electric conversion element 4 are connected to electrodes 36-38. Lead wires from electrodes 17 and 18 of second mechano-electric conversion element 16 are then connected to electrodes 34 and 35.

Next, the operation of the transducer device of the present invention and the recording/reproducing device using the same will be explained using FIG.

FIG. 2 shows the applied voltage-displacement static characteristics of the bimorph constituting the first mechanical-electrical transducer 3.4 and the laminated piezoelectric material constituting the second mechanical-electrical transducer 16. Similarly, FIG. 3 shows the dynamic characteristics of the applied voltage and the amount of displacement of each element.

As is clear from these characteristics, for example, if you want to obtain a predetermined displacement amount of 50 μm, the first mechanical-electrical conversion element 3
A voltage of 50V may be applied to and 4. Therefore, when comparing the amount of displacement of the first mechanical-electrical conversion elements 3 and 4 and the second mechanical-electrical conversion element 16 depending on the applied voltage, it is found that when the applied voltage is varied by ±IOV with respect to 50V, the first The displacement amount of mechanical-electric conversion elements 3 and 4 is 50μm±10μ
m. If the second mechanical-electrical transducer 16 is to be displaced by ±1 μm when the first mechanical-electrical transducer 16 has a predetermined displacement amount of 50 μm, an applied voltage of 20 V is applied to the second mechanical-electrical transducer 16. Good. That is,
In the configuration of the transducer device shown in FIG.
The ratio of the change in applied voltage of the mechanical-electrical conversion elements 3 and 4 and the second mechanical-electrical conversion element 16 was set to 10 times. The amount of displacement due to the applied voltage of the first mechanical-electrical conversion elements 3 and 4 and the second mechanical-electrical conversion element 16 is 1 μm/V, respectively.
, 0.1 μm/V.

As is clear from this, the first mechanical-electrical transducers 3 and 4 have a large displacement amount but a low response frequency, so they are used for coarse movement of the transducer 26, and the second mechanical-electrical transducer 16 is used for coarse movement of the transducer 26. Although the amount of displacement is small, the response frequency is high (several tens of KHz), so it was used for fine movement of the transducer 26.

Next, as an example of the use of the transducer device of the present invention shown in FIG.
A tracking method for reproducing information signals from recorded recording tracks will be described with reference to FIGS. 4 and 5, taking into consideration the dynamic characteristics shown in FIG. 3.

FIG. 4 is a block diagram of a tracking method using the transducer device of the present invention, and FIG. 5 is a waveform diagram for explaining the operation of each part in FIG. 4. The information signal processing circuit system is omitted in FIG. 4 because conventional techniques can be applied depending on the information signal recording method.

First, during recording, a voltage of 50 V DC is applied from the drive amplifier 52 between the drive electrodes 11 and 14 and the common electrodes 12 and 15 of the transducer device in FIG. 3 and 4 coarsely, while
No voltage is applied to the second mechanical-electric conversion element 16. In this state, an information signal is supplied to the transducer 26, and the information signal is sequentially recorded at a predetermined truck pitch on the recording medium 50 consisting of the substrate 50a and the recording magnetic material 50b, thereby creating a recording track (track width W) 51. control to form sequentially.

Next, a case will be described in which the recording track 51 formed in this manner is sequentially scanned by the transducer 26 and an information signal is reproduced.

The operation of the transducer 26 is, in principle, an application of a general auto-tracking method using wobbling.

In FIG. 4, as in the case of recording, a voltage of 50 V DC is applied from the drive amplifier 52 between the drive electrodes 11 and 14 and the common electrodes 12 and 15 of the transducer device, and the first mechanical-electric The transducer 26 is controlled to scan a predetermined recording track 51 by coarsely moving the transducer elements 3 and 4, and then the electrodes 17, 18 and the drive amplifier 5
4, an AC voltage of 50 V at several hundred to several thousand Hz is applied from the wobbling oscillator 53 to the second mechanical-electric conversion element 16. Then, the transducer 26 vibrates minutely in the stacking direction of the second mechanical-electric transducer 16, and vibrates in the width direction of the recording track 51, that is, in the tracking direction.

FIG. 5A-a shows a state in which the transducer 26 accurately tracks the recording track 51 while vibrating with an AC signal of period T applied to the second mechanical-electrical transducer 16. There is.

Therefore, in this case, the RF multiplied signal reproduced from the transducer 26 is obtained in the form of a waveform shown in FIG. It will be done. A signal having an output waveform A-c shown in FIG. 5A-c obtained from the output of the envelope detector 56 is sent to one input of a synchronous detector 57. On the other hand, the detection electrode 10 (or 13
゜It is not necessary to use the detection electrode 13 in the embodiment of FIG. An alternating current signal with a period T is detected and sent to the other input of the synchronous detector 57, and the signal of the output waveform A-c is synchronously detected using this signal. A signal with a waveform as shown in FIG. 5A-d is obtained at the output of the synchronous detector 57, and when this output signal A-d is applied to the low-pass filter 58, the voltage becomes zero, and the drive amplifier 52 has no voltage. No voltage is added either, so the transducer 26 continues to track normally.

If the tracking of the transducer 26 is
-a state to the state shown in FIG. 5 B-a (in the drawing,
5), the reproduced RF signal from the transducer 26 becomes as shown in FIG. 5B-b, and conversely, as shown in FIG. 5C-a ( 5), the reproduced RF signal from the transducer 26 is as shown in Fig. 5c-b.
The amplitudes and frequencies of both RF signals are the same, but their phases are opposite to each other. R
When the envelope of the F-fold signal -b or the RF-fold signal -b is detected by the envelope detector 56, FIG. 5B-c or FIG. 5C is obtained.
An output waveform B-c or an output waveform C-c having an exactly opposite phase as shown in FIG.

Then, the displacement amount of the first mechanical-electrical transducer 3.4 detected by the detection electrode 10 (or 13) and a signal having the same frequency as the vibration frequency of the second mechanical-electrical transducer 16 are detected by a synchronous detector 57. output waveform B-c or output waveform C-
When the signal of c is synchronously detected, as a result, the synchronous detector 57
An error signal B-d or error signal C-d having mutually opposite polarities as shown in FIG. 5B-d or FIG. 5C-d is obtained at the output.

This error signal is smoothed by a low-pass filter 58, and
A DC error voltage Be (E volts) or a DC error voltage Ce (E volts) having different polarities as shown in FIG. 5B-e or 5C-e is generated. This DC error voltage E is supplied to the drive amplifier 52 and superimposed on a predetermined DC drive voltage of 50V.
and 15 to control the first mechanical-electric conversion elements 3 and 4. In this way, transducer 2
6 performs continuous control so that the recording track 51 is correctly tracked.

As described above, it is detected that the phase of the reproduced RF signal from the transducer 26 becomes an opposite phase depending on the direction of deviation of the transducer 26 with respect to the recording track 51, and an error signal based on this is generated. The error signal allows the transducer 26 to auto-track.

〔Effect of the invention〕

The transducer device of the present invention has a function of slightly moving the transducer, so it can track with high precision, and therefore can highly reproduce information signals recorded at high density with a recording track width of 0 μm or less. Can be done with fidelity.

In addition, when a magnetic head is used as a transducer, the magnetic head is supported by the free ends of a pair of first mechanical-electrical transducers arranged in parallel, so that even if the first mechanical-electrical transducer is deformed, Because of the parallel movement, there is no elevation angle between the recording medium and the gap surface of the magnetic head, which also has the advantage that good contact can be maintained between the two.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the transducer device of the present invention, in which A is a plan view and B is a plan view of X, -X! A cross-sectional view along the line, FIG. 2 shows the static characteristics of the applied voltage-displacement amount of the bimorph constituting the first mechanical-electrical transducer and the laminated piezoelectric body constituting the second mechanical-electrical transducer, and FIG. 3 shows the static characteristics of the applied voltage-displacement amount. Similarly, the dynamic characteristics of applied voltage and displacement amount of each element are shown. FIG. 4 is a block diagram of a tracking method using the transducer device of the present invention, and FIG. 5 is a waveform diagram for explaining the operation of each part in FIG. 4. (Explanation of symbols) l...Base 2...Mounting hole 3.4...First mechanical-electric conversion element 5.6...Substrate 5a, 6a...Reference surface 7.8 .9...Lead wire groove 10.13...Detection electrode 11.14...Drive electrode 12.15...Common electrode 16...Second mechanical-electric conversion element 17.18...Electrode 19... Reinforcement plates 21-25... Piezoelectric bodies 27-29... Lead wires 30... Terminal plates 31-41... Electrodes 50... Recording medium 50a... Substrate 50b... Recording magnetic material 51...Recording track 52.54...Drive amplifier 53...Wobbling oscillator 56...Envelope detector 57...Synchronized detector 58...Low pass filter %2 Figure 1 machine - Is it an electric support element ()? Ref) 3.
4. Second mechanical map - Electrical transducer element (6 applied voltage for laminated piezoelectric material - Static characteristics of transformation amount

Claims (1)

[Claims] 1. A pair of first mechanical-electrical transducers are fixed to a substrate at a predetermined interval, and the free ends of the elements are connected by a second mechanical-electrical transducer; 1. A transducer device for converting information signals, characterized in that a transducer for converting information signals is fixed to at least one free end of a mechanical-electric conversion element. 2. A detection electrode is provided on one surface of at least one of the first mechanical-electrical conversion elements directly above or in the vicinity of the second mechanical-electrical conversion element, and a driving electrode is provided on the other part,
The transducer device for information signal conversion according to claim 1, characterized in that a common electrode is provided on the other surface of the element. 3. The first mechanical-electrical conversion element is configured to apply a voltage to cause a coarse displacement, and the second mechanical-electrical conversion element is configured to cause a fine displacement by applying a voltage. An information signal recording and reproducing device comprising the information signal conversion transducer device according to scope 1. 4. During recording, no voltage is applied to the second mechanical-electrical transducer, but a voltage is applied to the first mechanical-electrical transducer to hold the information signal converting transducer in a predetermined position and convert the information signal. When recording and reproducing, the first machine -
Claim 3, characterized in that the information signal conversion transducer reproduces the information signal while controlling the position by applying a voltage to both the electrical conversion element and the second mechanical-electrical conversion element. The information signal recording and reproducing device described in . 5. During reproduction, the coarse displacement of the information signal converting transducer is detected by the detection electrode provided on the first mechanical-electrical conversion element, and the detection signal is applied to the second mechanical-electrical conversion element to convert the information signal. 5. The information signal recording/reproducing apparatus according to claim 4, wherein the converting transducer is moved slightly to scan the recording track. 6. At the time of reproduction, a coarse displacement of the first mechanical-electrical transducer and a fine displacement of the second mechanical-electrical transducer are simultaneously detected by a detection electrode provided on the first mechanical-electrical transducer. An information signal recording and reproducing device according to claim 4.