Source: https://patents.google.com/patent/EP0450629A1/en
Timestamp: 2018-11-17 16:13:03
Document Index: 336563542

Matched Legal Cases: ['art 31', 'art 31', 'art 31', 'art 31', 'art 31', 'art 13', 'art 31']

EP0450629A1 - Recording and reproducing device and recording medium therefor - Google Patents
Recording and reproducing device and recording medium therefor Download PDF
EP0450629A1
EP0450629A1 EP19910105362 EP91105362A EP0450629A1 EP 0450629 A1 EP0450629 A1 EP 0450629A1 EP 19910105362 EP19910105362 EP 19910105362 EP 91105362 A EP91105362 A EP 91105362A EP 0450629 A1 EP0450629 A1 EP 0450629A1
EP19910105362
EP0450629B1 (en )
Takehisa C/O Sony Corporation Ishida
Hiroshi C/O Sony Corporation Takino
Fig. 4, is a sectional view taken along a line III-III of Fig. 3;
Referring now to the drawings, particularly to Figs. 1-6, Fig. 1 shows a magnetic disk recording and reproducing device, wherein a recording medium 1 is installed at a spindle 2 and in turn a head 3 is fixed to an extreme end of a supporting arm 40 of a head driving means 4. A control circuit 41 may output a track position instruction to a drive circuit 42 in response to the track moving information, the drive circuit 42 may supply an electrical power corresponding to the track position instruction to a voice coil motor 43 so as to move the supporting arm 40. The head 3 is moved on the recording medium 1 through an operation of the supporting arm 40 and a head element 30 of the head 3 may oppose against one of a plurality of track patterns, physically formed in advance, in the recording medium 1. in turn, if the spindle 2 is rotationally driven with a motor not shown, the recording medium 1 is rotated in a circumferential direction (a direction indicated by an arrow in Fig. 2) of the spindle 2. As shown in Fig. 2, the head 3 is floated from the recording medium 1 through a dynamic pressure produced by two grooves formed at the lower surface of the slider part 31 of the head 3, floating surfaces 33 positioned outside the two grooves and a viscosity of air through a rotation of the recording medium 1. Date is magnetically recorded in the track patterns 10 to which the head element 30 opposes or the data magnetically recorded in the track patterns 10 is reproduced.
As shown in Fig. 1, the magnetic disc recording and reproducing device of the first preferred embodiment is constructed such that the recording medium 1 is provided with electrical conducting layers corresponding to the track patterns 10 and in turn the slider part 31 of the head 3 is provided with at least a pair of electrodes 50 and 51 opposing to the electrical conducting layers of the electrostatic capacitance sensor 5. Electrostatic capacitances C₁ and C₂ generated between the pair of electrodes 50 and 51 and the electrical conducting layers are detected by the electrostatic capacitance sensor 5. A tracking error (et) corresponding to the sensed electrostatic capacitances C₁ and C₂ is calculated by a calculation means 6. The tracking error (et) of the result of calculation is fed back to the drive circuit 42 and the tracking of the head 3 is controlled.
More practically, the electrical conducting layers are constructed by a physical method that, as shown in Figs. 1 to 4, a plurality of track patterns 10 of different concentric diameters around the fixing hole 12 for the spindle 2 and a contact pattern 13 connecting these track patterns 10 to each other are closely vapor deposited on an entire upper surface of the main body 11 of the disc of the recording medium 1 of glass with layer of magnetic substance having an electrical conduction through a sputtering process, thereafter a resist patterns is formed on the magnetic layer through a photolithography process, a non-required part of the magnetic layer is etched with the resist pattern being applied as a mask and then the resist pattern is removed. An extended pat 13a of the contact pattern 13 extending from the innermost track pattern 10 to the fixing hole 12 is contacted with the spindle 2 by installing the recording medium 1 on the spindle 2 of the track pattern 10 show an earth potential.
As shown in Figs. 1 and 2, the pair of electrodes 50 and 51 are formed situated the side surface of the recording medium by the slider part 31 of the head 3 in such a way as they may oppositely face both side portions in a diameteral direction of one track pattern of the plurality of track patterns 10 opposing against the head element 30. That is, as shown in Fig. 5, under a condition in which the head element 30 oppositely faces against one track pattern 10 while its center is being coincided with a center of one track pattern 10 in its diameteral direction, the opposing areas S₁ and S₂ of the pair of electrodes 50 and 51 are extended from the recording medium surface of the slider part 31 to the side surface of the head element at both sides of the head element 30. Each of the lead patterns 52 and 53 is connected to the input terminal of the electrostatic capacitance sensor 5 shown in Fig. 1 through flexible lead lines 54 and 55, respectively.
As shown in Fig. 1, the calculation means 6 is provided with a subtractor 60 for calculating a pair of electrostatic capacitances C₁ and C₂ of outputs of the electrostatic sensor 5, an adder 61 for calculating a sum C⁺ of the pair of electrostatic capacitances C₁ and C₂ and a divider 62 for calculating a tracking error et = C⁻/C⁺ as a quotient in which the difference C_ is divided by the sum C⁺, and then the tracking error et corresponding to the electrostatic capacitances C₁ and C₂ is calculated as a geometrical mean of the electrostatic capacitances C₁ and C₂.
According to the configuration of the first preferred embodiment, the recording medium 1 is installed on the spindle 2, thereby a plurality of track patterns 10 become an earth potential through the contact pattern 13. Driving of the spindle 2 and input of track moving information to the control circuit 41 cause the head 3 to be floated on the recording medium 1 under an operative condition in which the head element 30 oppositely faces against one of a plurality of track patterns 10 in the recording medium 1, as shown in Figs. 5 and 6, a pair of electrodes 50 and 51 opposite.y face against one track pattern 10. As indicated in the following equations 1 and 2, between the opposing pair of electrodes 50 and 51 and one track pattern 10, are generated the electrostatic capacitances C₁ and C₂ corresponding to the opposing areas S₁ and S₂.
where, d is an amount of floating operation and ε is a dielectric constant of air.
The electrostatic capacitance sensor 5 detects electrostatic capacitances C₁ and C₂ generated between the pair of electrodes 50 and 51 and one track pattern 10, and the calculation means 6 composed of the subtractor 60, adder 61 and divider 62 may calculate the tracking error et corresponding to the detected electrostatic capacitances C₁ and C₂. The tracking error et calculated by the calculation means 6 becomes as follows in reference to the equations (1) and (2).
As apparent from this equation (23), the electrostatic capacitances C₁ and C₂ are detected to calculate the tracking error et not influenced by variation of the floating amount d, this calculated tracking error et is fed back from the calculation means 6 to the drive circuit 42. The drive circuit may supply an electrical power added with the tracking error e t got from the calculation means 6 to the track position instruction from the control circuit 41 to the voice coil motor 43, thereby the operating arm 40 may operate to cause the electrostatic capacitances C₁ and C₂ to be equal in real time. That is under a condition in which the head element 30 oppositely faces one track pattern 10 while its center is being coincided with a radial center of one track pattern 10, it is constructed such that the opposing areas S₁ and S₂ of the pair of electrodes 50, 51 and one track pattern 10 are make equal to each other, so that the tracking error et is fed back from the calculation means 6 to the drive circuit 42, and the head 3 is controlled for its tracking in such a way that a center of the head element 30 is coincided with a center of the track pattern 10 in real time.
A second preferred embodiment of the present invention is shown in Figs. 7 to 11. A feature of the second preferred embodiment, as shown in Fig. 8, is that electrostatic capacitance type additional information patterns 14 are arranged between the track patterns 10 of the recording medium 1A. As shown in Figs. 7 ;and 10, the track patterns 10 are physically formed by material having electrical conducting and magnetic characteristics so as to form the electrical conducting layers corresponding to the track patterns 10 are formed in the recording medium 1A, such that, under a condition in which the head element 30 is oppositely faced against one track pattern 10 while its center is being coincided with a radial center of one track pattern 10, a pair of electrodes 50A and 51A arranged in the slider part 31 may oppose the radial outer part of one track pattern and the radial inner part of its adjoining track pattern 10 and these opposing areas S₁ and S₂ are equal to each other, that as shown in Fig. 9, the sum C⁺ calculated at the adder 61 is extracted as additional information.
Accordingly, the structure of the second preferred embodiment shows that a plurality of track patterns 10 and the additional information patterns 14 as well as the extended part 13a are made of electrical conductive and magnetic material, so that installation of the recording medium 1A on the spindle 2 causes the plurality of track patterns 10 and the additional track patterns 14 to become the earth potential. Thus, as shown in Figs. 10 and 11, under a condition in which the head element 30 is oppositely faced against one of the plurality of track patterns 10 of the recording medium 1A to enable a recording and/or reproducing operation to be performed, a pair of electrodes 50A and 51A oppositely face one track pattern 10 opposing against the head element 30 and its adjacent track pattern 10, respectively. The electrostatic capacitance sensor 5 may detect the electrostatic capacitances C₁ and C₂ generated between the pair of electrodes 50A and 51A and the two track patterns 10. The calculation means 6 may calculate the tracking error et in response to the detected electrostatic capacitances C₁ and C₂ as follows;
The calculation result is fed back to the drive circuit 42 and then the tracking of the head 3 is controlled in such a way that the center of the head element 30 is coincided with the center of one track pattern 10. In cooperation with this controlling operation, in a case that the pair of electrodes 50A, 51A pass above the additional information patterns 14, the electrostatic capacitances C₁ and C₂ are increased by a corresponding area of the pair of electrodes 50A, 51A against the additional information patterns 14 so that, as shown in Fig. 9, the sum C⁺ calculated by the adder 61 is increased in response to the additional information 14. Accordingly, the sum C⁺ from the adder 61 is extracted as additional information, and this information can be utilized as an address information showing to what track pattern 10 the head element corresponds.
Figs. 12 and 13 show a third preferred embodiment according to the present invention. Features of the third embodiment include track patterns 10, physically formed or an electro-conductive and magnetic material to construct an electric conductive layer corresponding to the track patterns 10 in the recording medium 1. An even number of electrodes 50B, 50C, 50D, 50E, 50F, 51B, 51C, 51D, 51E, and 51F, numbering more than four are arranged at a side surface of the recording medium of the slider part 31, such that under a condition in which the head element 30 oppositely faces against one track pattern 10 with its center being coincided with a radial center of one track pattern 10, the electrodes 50B, 50C, 50D, 50E, 50F, 51B, 51C, 51D, 51E, and 51F are oppositely faced against four track patterns 10 adjacent to the electrodes and these opposing areas S₃, S₄, S₅, S₆, S₇, S₈, S₉, S₁₀, S₁₁, S₁₂, (S₁ = S₃ + S₄ + S₅ + S₆ + S₇ + S₈ + S₉ + S₁₀ + S₁₁ + S₁₂) become equal to each other, and the electrodes 50B, 50C, 50D, 50E, 50F, 51B, 51C, 51D, 51E, and 51F opposing one side of a radial direction of several track patterns 10 are connected in parallel at one input terminal of the electrostatic capacitance sensor 5, and several of the electrodes 51B, 51C, 51D, 51E and 51F opposing the other sides in the radial directions of several track patterns 10 are connected in parallel with the other input end of the electrostatic capacitance sensor 5.
Accordingly, the structure of the third preferred embodiment shows that several track patterns 10 and the contact patterns 13 are made of electrical conductive and magnetic material, so that installation of the recording medium 1 on the spindle 2 causes several track patterns to assume an earth potential. Accordingly, under a condition in which the head element 30 oppositely faces against one of several track patterns 10 or the recording medium 1 to enable a recording and/or reproducing operation to be performed, as shown in Fig. 13, an even number of electrodes 50B, 50C, 50D, 50E, 50F, 51B, 51C, 51D, 51E, and 51F oppositely face against one opposing track pattern 10 of the head element 30 and adjoining four track patterns 10, respectively and the electrostatic capacitance sensor 5 may detect the electrostatic capacitances C₃, C₄, C₅, C₆, C₇, C₈, C₉, C₁₀, C₁₁, C₁₂, (C₁ = C₃ + C₄ + C₅ + C₆ + C₇, C₂ = C₈ + C₉ + C₁₀ + C₁₁ + C₁₂) generated among the electrodes 50B, 50C, 50D, 50E, 50F, 51B, 51C, 51D, 51E, and 51F and the five track patterns 10 and then the calculation means 6 may calculate the tracking error as follows in response to the detected electrostatic capacitances C₁ and C₂.
The result of calculation is fed back to the drive circuit 42 and the tracking of the head 3 is controlled such that the center of the head element 30 is coincided with the center of one track pattern 10 in real time. In the third preferred embodiment, an even umber of electrodes more than four 50B, 50C, 50D, 50E, 50F, 51B, 51C, 51D, 51E, and 51F are provided arranges into to equal sets and connected in parallel with the in/out terminal of the electrostatic capacitance sensor 5, so that, as compared with the first and second preferred embodiment, it may detect variation of the electrostatic capacitance of n-times when electrodes of 2.n in number are provided. Thus, even in a case that the floating amount (d) of the head 3 from the recording medium 1 is varied or one electrode is small in size or the like, a sufficient S/N can be assured.
The present invention however, is not limited to the aforesaid embodiments, as shown in Fig. 6, for example, assuming that the potential of the electrode 50 is defined as V₁, its electrical charge is Q₁, a potential of the electrode 51 is V₂ and its electrical charge is Q₂, voltages V₁ and V₂ may be defined as;
and further, assuming that Q₁ = Q₂ is attained, the voltage V₂ becomes;
and a ratio of V₂ : V₁ becomes;
Substituting the equation (4) with the equations (1) and (2) shows the following relation;
Accordingly, the potential V₁ the electrode 50 is kept constant to cause the potential V₂ of the electrode 51 to become an amount proportional to a ratio between the opposing area S₁ and the opposing area S₂. Then, the potential V¹ which corresponds to C¹ is kept constant and a varying amount of the potential V² corresponding to C² is applied as the tracking error et, thereby the calculation means 6 may be eliminated.
As described above, according to the present invention, the head oppositely faces against one of several track patterns in the recording medium to enable a recording and/or reproducing operation to be carried out, wherein the electrostatic capacitances generated between the electrodes and the electrical conducting layers can be controlled in real time in response to a tracking error value corresponding to the detected electrostatic capacitances. In addition, in cooperation with tracking control of the head, an increased amount of the electrostatic capacitance in a case that the electrodes pass over the additional information patters, this increased electrostatic capacitance can be extracted as additional information such as address information. Thus, highly accurate tracking, which can endure against a disturbance may be attained and, in addition, it is easily possible to accomplish recording or a high data capacity through effective utilization of surplus area in the recording medium and the narrow tracking possible according to the invention.
head slider means having at least a pair of electrodes on a bottom surface thereof, said electrodes being opposed to conductive stripes provided on a magnetic disc;
means for detecting capacitances between said electrodes and said conductive stripes;
tracking error signal detecting means connected to said capacitance detecting means for generating tracking error signals; and
means for feeding back said tracking error signal to said head drive means.
A recording and/or reproducing apparatus as set forth in claim 1, wherein said tracking error signal detecting means includes adder means for adding capacitances between said electrodes and said conductive stripes, subtractor means for subtracting capacitances between said electrodes and said conductive stripes, and dividing means for obtaining output ratios of said subtractor means and said adder means.
magnetic tracks provided on said base disc; and
conductive stripes provided on said base disc in relation to said magnetic tracks for detecting tracking error conditions.
A magnetic recording medium as set forth in claim 3, wherein conductive bridge stripes are provided between said adjacent conductive stripes for storing additional information.
In a recording and reproducing device in which a head is position opposing track patterns physically formed in advance in a recording medium so as to perform a recording and/or reproducing operation, an improvement whereby said recording medium is provided with electro-conductive layers corresponding to the track patterns, and said head is provided with a sliding means and at least two electrodes for sensing an electrostatic capacitance so as to control tracking of the head.
In a recording and reproducing device in which a head is position opposing track patterns physically formed in advance in a recording medium so as to perform a recording and/or reproducing operation, an improvement whereby said recording medium is provided with electro-conductive layers corresponding to the track patterns, an additional information pattern of an electrostatic capacitance sensing type being arranged between the track patterns of the recording medium, the slider means of said head being provided with at least a pair of electrodes for use in detecting an electrostatic capacitance to oppose said electro-conductive layer, tracking of said head being controlled thereby, and an increased electrostatic capacitance caused by said additional information pattern is extracted as additional data.
In a recording medium in which the track patterns are physically formed in advance, the improvement comprising:    an additional information pattern of an electrostatic capacitance type is arranged between the track patterns.
EP19910105362 1990-04-06 1991-04-04 Recording and reproducing device and recording medium therefor Expired - Lifetime EP0450629B1 (en)
JP91618/90 1990-04-06
EP0450629A1 true true EP0450629A1 (en) 1991-10-09
EP0450629B1 EP0450629B1 (en) 1995-08-09
EP19910105362 Expired - Lifetime EP0450629B1 (en) 1990-04-06 1991-04-04 Recording and reproducing device and recording medium therefor
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JPWO2008075432A1 (en) * 2006-12-21 2010-04-08 東芝ストレージデバイス株式会社 The magnetic recording medium and magnetic recording device
EP1318513A3 (en) * 2001-12-06 2005-12-28 Samsung Electronics Co., Ltd. Information storage apparatus using charge
EP1538608A3 (en) * 2003-10-20 2007-12-19 Quantum Corporation Electromagnetic void-sensing probes and position control systems
US5488519A (en) 1996-01-30 grant
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