JP2004220743A - Information recording device, information recording control method, information reproducing device, information reproduction control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize good recording/reproducing considering surface-wobbling of a disk type optical recording medium. <P>SOLUTION: This device is provided with a storage part 31 storing surface-wobbling quantity of the prescribed radius of a disk type optical recording medium 51, a near field light emitting part 7 converging a light beam emitted from a light source 3 and emitting a light beam converged when it is arranged at a near field for an information recording plane of the disk type optical recording medium 51 as near field light, a first control part 30 generating a control signal by multiplying surface-wobbling quantity read out from the storage part 31 by the prescribed gain and controlling the near field light emitting part 7 so that the near field light emitting part 7 follows to surface-wobbling quantity, and a second control part 40 controlling the near field light emitting part 7 so as to keep the prescribed distance in the near field for the information recording plane based on a linear characteristic of return light quantity of the near field light. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an information recording device and an information recording control method for performing recording and reproduction using evanescent light, and an information reproduction device and an information reproduction control method.
[0002]
[Prior art]
Of the recording media, a removable optical disc that is mounted on a device and subjected to recording processing or reproduction processing is held by the apparatus by clamping the center of the disc, so that recording or reproduction is performed by a rotational movement. In addition, the optical disk tends to oscillate up and down with the clamp point as a fulcrum.
[0003]
The cause of such a run-out on the removable recording medium may be caused by disturbances such as tilting of the clamp portion and distortion of the recording medium caused by pinching dust or the like during clamping.
[0004]
If a rotating optical disc is deflected, a focus error is likely to occur mainly during recording or reproduction. Therefore, in a removable optical disk, a certain amount of runout is allowed in the format, and the runout allowed by a focus servo mechanism of a device for mounting, recording, or reproducing the optical disk is addressed. For example, in a DVD (Digital Versatile Disc) or the like, a deviation of ± 300 μm is allowed in the format.
[0005]
By the way, in a device that records or reproduces predetermined information by irradiating a recording medium such as an optical disk with light, the use of evanescent light enables high-density recording and reproduction beyond the diffraction limit of light. Has been devised.
[0006]
As a technique for recording on a recording medium and reproducing from the recording medium using evanescent light, a technique using SIL (Solid Immersion Lens) for an evanescent light generating lens is widely known.
[0007]
In order to realize the recording and reproduction by the evanescent light, the SIL and the aspherical lens are combined and used as a second group lens so that the numerical aperture NA is 1 or more, and the distance (gap) to the information recording surface of the recording medium is reduced. ) Must be less than half the wavelength of the light beam incident on the SIL. For example, if the wavelength λ of the light beam is 400 nm, the gap is 200 nm or less.
[0008]
Further, in order to perform good recording and reproduction, it is necessary to keep the gap constant. Therefore, a method has been devised in which an optical head equipped with the above SIL is used to servo-control an actuator of the optical head to follow an information recording surface by using a difference in return light amount as an error signal. (For example, refer to Patent Document 1).
[Patent Document 1]
JP 2001-76358 A
[0009]
[Problems to be solved by the invention]
As described above, in order to achieve good recording and reproduction using evanescent light, the gap, which is a very short distance on the order of nanometers, is kept constant and the optical head follows the information recording surface of the recording medium. You need to control.
[0010]
When the recording medium is removable, the above-described disturbance occurs due to disturbance as described above. In a system using such evanescent light, it is necessary to maintain a gap on the order of nanometers. There is a problem that it becomes large.
[0011]
For example, assuming that the gap is 100 nm and the allowable gap error is ± 1%, it is necessary to suppress the gap error to ± 1 nm or less. In such a system, when a deviation of about ± 300 μm, which is an allowable range in a DVD or the like, occurs, the DC gain required for the servo control is 100 dB or more, but the DC gain required for the servo control is 100 dB or more. In general, it is very difficult to design a stable control system while ensuring the above.
[0012]
To cope with this, if the amount of surface deviation of the recording medium is suppressed to, for example, ± 10 μm or less in advance, there is a problem that the removable property of the recording medium is lost.
[0013]
Although it is conceivable to relax the condition of the allowable gap error, there is a problem that good recording and reproduction cannot be realized, such as deterioration of a reproduction RF signal.
[0014]
Therefore, the present invention has been devised in order to solve the above-described problem, and it is possible to perform good recording and reproduction by using a removable recording medium in consideration of the influence of surface shake due to disturbance. It is an object to provide an information recording device and an information recording control method, and an information reproducing device and an information reproduction control method.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, an information recording apparatus according to the present invention comprises a mounting means for mounting a removable disk-shaped optical recording medium, and rotating the disk-shaped optical recording medium mounted on the mounting means at a predetermined rotation speed. Rotation driving means for generating the pulse signal, N (N is a natural number) pulse signal generation means for generating N (N is a natural number) pulse signals at a predetermined period during one rotation of the disk-shaped optical recording medium by the rotation driving means, Counting means for counting the N pulse signals generated by the means; and a surface deviation amount having a predetermined radius detected at a timing at which the pulse signal is generated by the pulse signal generating means. Storage means for storing the light beam having a predetermined wavelength modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium. A light source and a light beam emitted from the light source are condensed, and the information beam is focused on the information recording surface of the disc-shaped optical recording medium when the information beam is disposed in a near field with respect to the information recording surface. Near-field light emitting means for emitting the light beam, and detecting radial position information indicating a radial position of an information recording surface of the disc-shaped optical recording medium to which the near-field light emitting means irradiates the light beam. Means, gain generating means for generating a predetermined gain corresponding to the radial position information detected by the radial position information detecting means, and the storage means according to the count value of the pulse signal counted by the counting means. A surface shake amount reading means for reading the stored surface shake amount, and the surface shake amount read by the surface shake amount read means, are generated by the gain generation means. A first control unit that generates a control signal by multiplying the predetermined gain by the predetermined gain, and controls the near-field light emitting unit to follow the surface shake amount; Returning light amount detecting means for detecting the returning light amount of the near-field light; and the near-field light emitting means based on the linear characteristic of the returning light amount of the near-field light detected by the returning light amount detecting means, with respect to the information recording surface. And a second control means for controlling so as to maintain a predetermined distance in the near field.
[0016]
In order to achieve the above object, an information recording control method according to the present invention includes a mounting step of mounting a removable disk-shaped optical recording medium, and a rotation step of rotating the mounted disk-shaped optical recording medium at a predetermined rotation speed. A driving step, a pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined period during one rotation of the disk-shaped optical recording medium by the rotation driving step, and a pulse signal generating step. A counting step of counting the generated N pulse signals, and a surface deviation amount of a predetermined radius detected at a timing when the pulse signal is generated in the pulse signal generating step corresponds to the count value in the counting step. And a storage step of storing the information in a storage means, and a predetermined light output from a light source after being modulated by recording information to be recorded on an information recording surface of the disc-shaped optical recording medium. A near-field light emitting unit disposed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, and emits the focused light beam as near-field light to the information recording surface. A near-field light emitting step, and a radial position information detecting step of detecting radial position information indicating a radial position of an information recording surface of the disc-shaped optical recording medium on which the near-field light emitting unit irradiates the light beam. A gain generating step of generating a predetermined gain corresponding to the radial position information detected by the radial position information detecting step; and a gain value stored in the storing step according to a count value of the pulse signal counted by the counting step. A surface blur amount readout step for reading out the surface blurring amount, and the surface blurring amount read out in the surface blurring amount reading out step, wherein A first control step of generating a control signal by multiplying the near-field light by the constant gain and controlling the near-field light emitting means to follow the surface shake amount; and a near-field light emitted to the information recording surface. The near-field light emitting means and the information recording surface are close to each other based on a linear characteristic of the return light amount of the near-field light detected by the return light amount detection step. And a second control step of performing control so as to keep a predetermined distance in the hall.
[0017]
In order to achieve the above object, an information recording apparatus according to the present invention comprises a mounting means for mounting a removable disk-shaped optical recording medium, and rotating the disk-shaped optical recording medium mounted on the mounting means at a predetermined rotation speed. Rotation driving means for generating the pulse signal, N (N is a natural number) pulse signal generation means for generating N (N is a natural number) pulse signals at a predetermined period during one rotation of the disk-shaped optical recording medium by the rotation driving means, Counting means for counting the N pulse signals generated by the means, and the amount of surface deviation detected at the timing at which the pulse signal is generated by the pulse signal generating means, Storage means for storing information in association with information; and a light beam having a predetermined wavelength modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium. A light source for emitting light, and a light beam emitted from the light source. The light beam emitted from the light source is focused on the information recording surface of the disc-shaped optical recording medium. Near-field light emitting means for emitting to a recording surface, and a radial position for detecting radial position information indicating a radial position of an information recording surface of the disc-shaped optical recording medium to which the near-field light emitting means irradiates the light beam. Reading the amount of surface deviation stored in the storage unit according to the information detection unit, the count value of the pulse signal counted by the counting unit, and the radial position information detected by the radial position information detection unit; The near-field light emitting unit is configured to follow the surface shake amount based on the surface shake amount read unit and the surface shake amount read by the surface shake amount read unit. First control means for controlling, return light quantity detection means for detecting return light quantity of near-field light emitted to the information recording surface, and linear characteristic of return light quantity of near-field light detected by the return light quantity detection means And a second control unit for controlling the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on the above.
[0018]
In order to achieve the above object, an information recording control method according to the present invention includes a mounting step of mounting a removable disk-shaped optical recording medium, and a rotation step of rotating the mounted disk-shaped optical recording medium at a predetermined rotation speed. A driving step, a pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined period during one rotation of the disk-shaped optical recording medium by the rotation driving step, and a pulse signal generating step. A counting step of counting the generated N pulse signals; and a face shake amount detected at a timing at which the pulse signal is generated in the pulse signal generating step is calculated by using the count value in the counting step, radial position information, And a storage step of storing the information in the storage means in association with the light emitted from the light source modulated by the recording information recorded on the information recording surface of the disc-shaped optical recording medium. A light beam having a predetermined wavelength is condensed, and near-field light emitting means arranged in a near field with respect to the information recording surface of the disc-shaped optical recording medium, uses the condensed light beam as near-field light to generate the near-field light. Emitting near-field light, and detecting radial position information indicating a radial position of the information recording surface of the disc-shaped optical recording medium on which the near-field light emitting means is irradiating the light beam. A step of reading out the amount of the runout stored in the storage step according to the step, the count value of the pulse signal counted in the counting step, and the radial position information detected in the radial position information detecting step. And controlling the near-field light emitting means to follow the surface shake amount based on the surface shake amount read in the amount readout step and the surface shake amount readout step. 1, a return light amount detecting step of detecting a return light amount of the near-field light emitted to the information recording surface, and a linear characteristic of the return light amount of the near-field light detected by the return light amount detection step. A second control step of controlling the near-field light emitting means to maintain a predetermined distance in the near field with respect to the information recording surface.
[0019]
In order to achieve the above object, an information recording apparatus according to the present invention is provided with a mounting means for mounting a removable disk-shaped optical recording medium, and information modulated by recording information to be recorded on an information recording surface of the disk-shaped optical recording medium. A light source that emits a light beam having a predetermined wavelength, an optical unit that collects a light beam emitted from the light source and emits the information beam to an information recording surface of the disk-shaped optical recording medium, and an optical unit that emits the light beam. Surface shake amount detection means for detecting the surface shake amount of the disc-shaped optical recording medium from the return light of the light beam, and condensing the light beam emitted from the light source to the information recording surface of the disc-shaped optical recording medium A near-field light emitting unit that emits the condensed light beam to the information recording surface as the near-field light when arranged in the near field, and a return light amount of the near-field light emitted to the information recording surface. The returning light amount detecting means and the surface shake amount detected by the surface shake amount detecting means are equal to or greater than a first threshold, and the near-field light emitting means is set to the surface shake amount based on the surface shake amount. A first control unit for controlling to follow, and a return of the near-field light detected by the return light amount detection unit when the surface deviation detected by the surface deviation detection unit is smaller than the first threshold value. A second control unit configured to control the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on a linear characteristic of a light amount.
[0020]
In order to achieve the above object, an information recording control method according to the present invention includes a mounting step of mounting a removable disk-shaped optical recording medium, and modulation by recording information to be recorded on an information recording surface of the disk-shaped optical recording medium. A light beam of a predetermined wavelength emitted from the emitted light source is condensed, and the amount of surface deviation of the disc-shaped optical recording medium is detected from the return light of the light beam emitted to the information recording surface of the disc-shaped optical recording medium. And a near-field light emitting unit disposed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, the light beam emitted from the light source being condensed, A near-field light emission step of emitting a beam as the near-field light to the information recording surface, a return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface, and a surface shake amount detection step Yo A first control step of controlling the near-field light emitting means to follow the above-mentioned surface shake amount, and detecting the surface shake amount by the surface shake amount detection step. If the detected surface shake amount is smaller than the first threshold value, the near-field light emitting unit is controlled to emit the near-field light based on the linear characteristic of the return light amount of the near-field light detected in the return light amount detection step. And a second control step of performing control so as to maintain a predetermined distance in the near field.
[0021]
In order to achieve the above object, an information reproducing apparatus according to the present invention comprises a mounting means for mounting a removable disk-shaped optical recording medium, and rotating the disk-shaped optical recording medium mounted on the mounting means at a predetermined rotation speed. Rotation driving means for generating the pulse signal, N (N is a natural number) pulse signal generation means for generating N (N is a natural number) pulse signals at a predetermined period during one rotation of the disk-shaped optical recording medium by the rotation driving means, Counting means for counting the N pulse signals generated by the means; and a surface deviation amount having a predetermined radius detected at a timing at which the pulse signal is generated by the pulse signal generating means. A light source that emits a light beam of a predetermined wavelength for reproducing predetermined information recorded on the disk-shaped optical recording medium; A near-field that converges the light beam emitted from the optical disc and emits the condensed light beam as near-field light to the information recording surface when disposed in the near field with respect to the information recording surface of the disc-shaped optical recording medium Light emitting means; radial position information detecting means for detecting radial position information indicating a radial position of an information recording surface of the disc-shaped optical recording medium to which the near-field light emitting means is irradiating the light beam; Gain generation means for generating a predetermined gain corresponding to the radial position information detected by the position information detection means; and a surface stored in the storage means according to the count value of the pulse signal counted by the count means. A surface blur amount reading means for reading a blur amount, and the predetermined amount generated by the gain generating means on the surface blur amount read by the surface blur amount reading means. First control means for generating a control signal by multiplying the gain and controlling the near-field light emitting means to follow the surface shake amount, and returning the near-field light emitted to the information recording surface; A near-field light emitting unit configured to detect the near-field light emitting unit in the near field with respect to the information recording surface based on a linear characteristic of a returning light amount of the near-field light detected by the returning light amount detecting unit; And second control means for controlling the distance to be maintained.
[0022]
In order to achieve the above object, an information reproduction control method according to the present invention includes a mounting step of mounting a removable disk-shaped optical recording medium, and a rotation step of rotating the mounted disk-shaped optical recording medium at a predetermined rotation speed. A driving step, a pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined period during one rotation of the disk-shaped optical recording medium by the rotation driving step, and a pulse signal generating step. A counting step of counting the generated N pulse signals, and a surface deviation amount of a predetermined radius detected at a timing when the pulse signal is generated in the pulse signal generating step corresponds to the count value in the counting step. And a light source for emitting a light beam of a predetermined wavelength for reproducing predetermined information recorded on the disk-shaped optical recording medium. A light beam emitted from a light source is condensed, and a near-field light emitting unit arranged in a near field with respect to an information recording surface of the disc-shaped optical recording medium, uses the collected light beam as a near-field light to record the information. A near-field light emitting step of emitting light to a surface, and radial position information for detecting radial position information indicating a radial position of an information recording surface of the disk-shaped optical recording medium to which the near-field light emitting means is irradiating the light beam. A detecting step; a gain generating step of generating a predetermined gain corresponding to the radial position information detected by the radial position information detecting step; and the storage means according to a count value of the pulse signal counted by the counting step. In the gain generation step, the surface blur amount read out in the surface blur amount reading step for reading the surface blur amount stored in A first control step of generating a control signal by multiplying the predetermined gain to be performed and controlling the near-field light emission step to follow the surface shake amount; and outputting the control signal to the information recording surface. Returning light amount detecting means for detecting the returning light amount of the near-field light, and the near-field light emitting means based on the linear characteristic of the returning light amount of the near-field light detected by the returning light amount detecting step. And a second control step of performing control so as to maintain a predetermined distance in a near field with respect to.
[0023]
In order to achieve the above object, an information reproducing apparatus according to the present invention comprises a mounting means for mounting a removable disk-shaped optical recording medium, and rotating the disk-shaped optical recording medium mounted on the mounting means at a predetermined rotation speed. Rotation driving means for generating the pulse signal, N (N is a natural number) pulse signal generation means for generating N (N is a natural number) pulse signals at a predetermined period during one rotation of the disk-shaped optical recording medium by the rotation driving means, Counting means for counting the N pulse signals generated by the means, and the amount of surface deviation detected at the timing at which the pulse signal is generated by the pulse signal generating means, Storage means for storing in association with information, a light source for emitting a light beam of a predetermined wavelength for reproducing predetermined information recorded on the disk-shaped optical recording medium, The light beam emitted from the recording light source is condensed, and when placed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, the condensed light beam is emitted to the information recording surface as near-field light. Near-field light emitting means, radial position information detecting means for detecting radial position information indicating the radial position of the information recording surface of the disc-shaped optical recording medium to which the near-field light emitting means is irradiating the light beam, A surface blur amount reading unit that reads the surface blur amount stored in the storage unit according to the count value of the pulse signal counted by the counting unit and the radial position information detected by the radial position information detecting unit. A first control unit that controls the near-field light emitting unit to follow the surface shake amount based on the surface shake amount read by the surface shake amount read unit. Control means, a return light quantity detecting means for detecting a return light quantity of the near-field light emitted to the information recording surface, and a linear characteristic of the return light quantity of the near-field light detected by the return light quantity detection means. A second control unit that controls the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface.
[0024]
In order to achieve the above object, an information reproduction control method according to the present invention includes a mounting step of mounting a removable disk-shaped optical recording medium, and a rotation step of rotating the mounted disk-shaped optical recording medium at a predetermined rotation speed. A driving step, a pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined period during one rotation of the disk-shaped optical recording medium by the rotation driving step, and a pulse signal generating step. A counting step of counting the generated N pulse signals; and a face shake amount detected at a timing at which the pulse signal is generated in the pulse signal generating step is calculated by using the count value in the counting step, radial position information, A storage step of storing the information in the storage means in association with the optical disk, and light of a predetermined wavelength emitted from a light source for reproducing predetermined information recorded on the disk-shaped optical recording medium. A near-field light emitting means disposed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, wherein the near-field light emitting means emits the focused light beam as near-field light to the information recording surface. A field light emitting step, and a radial position information detecting step of detecting radial position information indicating a radial position of an information recording surface of the disc-shaped optical recording medium to which the near-field light emitting step is irradiating the light beam; A count value of the pulse signal counted by the counting step, and a surface blur amount reading step of reading the surface blur amount stored in the storage step according to the radial position information detected by the radial position information detecting step. A first control step of controlling the near-field light emission step to follow the surface shake amount based on the surface shake amount read in the surface shake amount reading step; A return light amount detecting step of detecting a return light amount of the near-field light emitted to the information recording surface; and the near-field light emission based on a linear characteristic of the return light amount of the near-field light detected by the return light amount detection step. A second control step of controlling the step to maintain a predetermined distance in the near field with respect to the information recording surface.
[0025]
In order to achieve the above object, an information reproducing apparatus according to the present invention includes a mounting means for mounting a removable disk-shaped optical recording medium, and a predetermined information recorded on an information recording surface of the disk-shaped optical recording medium. A light source that emits a light beam of a predetermined wavelength to be reproduced; an optical unit that collects a light beam emitted from the light source and emits the information beam to an information recording surface of the disk-shaped optical recording medium; Surface shake amount detection means for detecting the surface shake amount of the disc-shaped optical recording medium from the returned light of the light beam, and condensing the light beam emitted from the light source to form an information recording surface of the disc-shaped optical recording medium. A near-field light emitting unit that emits the condensed light beam as near-field light to the information recording surface when disposed in a near-field with respect to the information recording surface, and detects a return light amount of the near-field light emitted to the information recording surface Return light amount detection means, and first control means for controlling the driving means based on the surface shake amount when the surface shake amount detected by the surface shake amount detection means is equal to or more than a first threshold value; When the surface shake amount detected by the surface shake amount detection means is smaller than the first threshold, the near-field light emission is performed based on the linear characteristic of the return light amount of the near-field light detected by the return light amount detection means. Second means for controlling the means to maintain a predetermined distance in the near field with respect to the information recording surface.
[0026]
In order to achieve the above object, an information reproduction control method according to the present invention includes a mounting step of mounting a removable disk-shaped optical recording medium, and a predetermined information recorded on an information recording surface of the disk-shaped optical recording medium. A light beam of a predetermined wavelength emitted from a light source for reproducing the light is focused, and the amount of surface deviation of the disc-shaped optical recording medium is determined from the return light of the light beam emitted to the information recording surface of the disc-shaped optical recording medium. A step of detecting a surface shake amount to be detected, and condensing a light beam emitted from the light source, and near-field light emitting means arranged in a near field with respect to an information recording surface of the disc-shaped optical recording medium, the condensed light beam A near-field light emission step of emitting a light beam as the near-field light to the information recording surface, a return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface, and the surface shake amount detection step By When the emitted surface shake amount is equal to or more than a first threshold value, it is detected by a first control step of controlling the near-field light emitting unit to follow the surface shake amount and the surface shake amount detection step. When the surface shake amount is smaller than the first threshold value, the near-field light emitting unit is controlled based on the linear characteristic of the return light amount of the near-field light detected in the return light amount detection step. A second control step of performing control so as to maintain a predetermined distance in the near field.
[0027]
In order to achieve the above object, an information recording apparatus according to the present invention comprises: a mounting means for mounting a removable disk-shaped optical recording medium; and a rotation driving means for rotating the disk-shaped optical recording medium mounted on the mounting means. A pulse signal generating means for generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means; and a pulse signal generating means. Voltage value conversion means for converting the frequency of the pulse signal into a voltage value, voltage value comparison means for comparing the voltage value converted by the voltage value conversion means with a predetermined reference voltage value, and voltage value comparison means First rotation speed control means for controlling the rotation speed of the rotation drive means based on the comparison result; phase of the pulse signal generated by the pulse signal generation means; A second rotation speed control unit that controls the rotation speed of the rotation driving unit based on the comparison result by the phase comparison unit; A light source that emits a light beam having a predetermined wavelength modulated by recording information to be recorded; and a light source that collects the light beam emitted from the light source and is disposed in a near field with respect to an information recording surface of the disc-shaped optical recording medium. In this case, near-field light emitting means for emitting the collected light beam to the information recording surface as near-field light, and return light amount detecting means for detecting the return light amount of the near-field light emitted to the information recording surface The near-field light emitting unit is moved to a predetermined distance (gap) in the near field with respect to the information recording surface based on the linear characteristic of the returning light amount of the near-field light detected by the returning light amount detecting unit. ), And the first drive control means controls the rotation drive means so that the disk-shaped optical recording medium rotates at a predetermined rotation speed. The control by the second rotation speed control means is started in response to the rotation speed of the first rotation speed control unit, and in response to the result of the phase comparison by the phase comparison unit being equal to or less than a predetermined threshold value, Control means for starting control by the gap control means.
[0028]
In order to achieve the above object, an information recording control method according to the present invention includes a mounting step of mounting a removable disk-shaped optical recording medium, and a rotation driving step of rotating the mounted disk-shaped optical recording medium by rotation driving means. A pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means; and a pulse signal generating step. A voltage value converting step of converting the frequency of the pulse signal into a voltage value, a voltage value comparing step of comparing the voltage value converted in the voltage value converting step with a predetermined reference voltage value, and a voltage value comparing step A first rotation speed control step of controlling the rotation speed of the rotation driving means based on the comparison result by the step (b), and a phase of the pulse signal generated in the pulse signal generation step; A phase comparison step of comparing the phase of the quasi-signal, a second rotation number control step of controlling the rotation number of the rotation driving means based on the comparison result of the phase comparison step, A near-field light emitting means for converging a light beam of a predetermined wavelength emitted from a light source after being modulated by recording information to be recorded on an information recording surface, and arranged in a near field with respect to the information recording surface of the disc-shaped optical recording medium; The near-field light emission step of emitting the collected light beam as the near-field light to the information recording surface, and a return light amount detection step of detecting the return light amount of the near-field light emitted to the information recording surface, On the basis of the linear characteristic of the return light quantity of the near-field light detected in the return light quantity detection step, the near-field light emitting means is moved to a predetermined distance (gap) in the near field with respect to the information recording surface. A first gap control step for controlling the rotation of the disk-shaped optical recording medium at a predetermined number of rotations by the first rotation number control step; The control in the second rotation speed control step is started in response to the number of rotations, and the first gap control is performed in response to the result of the phase comparison in the phase comparison step being equal to or less than a predetermined threshold. And a control step of starting control by the step.
[0029]
In order to achieve the above object, an information reproducing apparatus according to the present invention includes a mounting unit for mounting a removable disk-shaped optical recording medium, a rotation driving unit for rotating the disk-shaped optical recording medium mounted on the mounting unit, Pulse signal generating means for generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means; and pulses generated by the pulse signal generating means. Voltage value conversion means for converting the frequency of the signal into a voltage value, voltage value comparison means for comparing the voltage value converted by the voltage value conversion means with a predetermined reference voltage value, and comparison by the voltage value comparison means First rotation speed control means for controlling the rotation speed of the rotation drive means based on the result, a phase of the pulse signal generated by the pulse signal generation means, and a phase of a predetermined reference signal A second rotation speed control unit for controlling the rotation speed of the rotation drive unit based on the comparison result by the phase comparison unit; and a predetermined information recorded on the disk-shaped recording medium. A light source that emits a light beam of a predetermined wavelength for reproducing the light, and a light beam emitted from the light source. The light beam is condensed. A near-field light emitting unit that emits the emitted light beam as the near-field light to the information recording surface, a return light amount detecting unit that detects a return light amount of the near-field light emitted to the information recording surface, and the return light amount detection Controlling the near-field light emitting means so as to maintain a predetermined distance (gap) in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the near-field light detected by the means. The first gap control means and the first drive control means control the rotation drive means so that the disk-shaped optical recording medium rotates at a predetermined rotation speed. Accordingly, the control by the second rotation speed control means is started, and the control by the first gap control means is performed in response to the result of the phase comparison by the phase comparison means being equal to or less than a predetermined threshold value. And control means for starting.
[0030]
In order to achieve the above-mentioned object, an information reproduction control method according to the present invention comprises a mounting step of mounting a removable disk-shaped optical recording medium, and a rotating step of rotating the mounted removable disk-shaped optical recording medium by rotation driving means. A driving step, a pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means, and a pulse signal generating step. A voltage value conversion step of converting the frequency of the generated pulse signal into a voltage value; a voltage value comparison step of comparing the voltage value converted in the voltage value conversion step with a predetermined reference voltage value; A first rotation number control step of controlling the rotation number of the rotation driving means based on a comparison result in the comparison step; and a pulse signal generated in the pulse signal generation step. A phase comparison step of comparing a phase of a predetermined reference signal; a second rotation number control step of controlling a rotation number of the rotation driving means based on a comparison result of the phase comparison step; A near-field light emitting unit that condenses a light beam having a predetermined wavelength emitted from a light source that reproduces predetermined information recorded on a recording medium, and is disposed in a near field with respect to an information recording surface of the disc-shaped optical recording medium. The near-field light emission step of emitting the collected light beam as the near-field light to the information recording surface, and a return light amount detection step of detecting the return light amount of the near-field light emitted to the information recording surface, The near-field light emitting means is kept at a predetermined distance (gap) in the near field with respect to the information recording surface based on the linear characteristic of the returning light amount of the near-field light detected in the returning light amount detecting step. A first gap control step of controlling the rotation of the disk-shaped optical recording medium at a predetermined rotation speed by the first rotation speed control step so that the disk-shaped optical recording medium rotates at a predetermined rotation speed. In response, the control by the second rotation speed control step is started, and when the result of the phase comparison by the phase comparison step becomes equal to or less than a predetermined threshold value, the control by the first gap control step is performed. And a control step of starting control.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of an information recording apparatus, an information recording control method, an information reproducing apparatus, and an information reproducing control method according to the present invention will be described in detail with reference to the drawings.
[0032]
The present invention is applied to the information recording device 50 shown in FIG. 1 as the first embodiment. The information recording device 50 mounts a removable disk-shaped optical recording medium 51 on a mounting portion (not shown), and irradiates the mounted disk-shaped optical recording medium 51 with evanescent light detected in a near field (near field) to obtain information. Record
[0033]
The information recording device 50 includes an information source 1 that supplies information to be recorded on the disc-shaped optical recording medium 51, an APC (Auto Power Controller) 2, a laser diode (LD) 3, a collimator lens 4, a beam splitter ( BS) 5, a mirror 6, an optical head 7, a condenser lens 52, a photo detector (PD) 12, a spindle motor 16, a feed base 17, a feed motor 18, a potentiometer 19, and a control system. 20.
[0034]
The APC 2 controls so as to modulate the laser light emitted from the laser diode 3 provided at the subsequent stage according to the information supplied from the information source 1 at the time of recording.
[0035]
The laser diode 3 emits a laser beam having a predetermined wavelength under the control of the APC 2. For example, the laser diode 3 is a red semiconductor laser, a blue-violet semiconductor laser, or the like.
[0036]
The collimator lens 4 emits the laser light emitted from the laser diode 3 as a light beam parallel to the optical axis.
[0037]
The beam splitter 5 transmits the light beam emitted from the collimator lens 4 and emits the light beam to the mirror 6. Further, the beam splitter 5 reflects the return light from the optical head 7 reflected by the mirror 6 and emits it to the condenser lens 52.
[0038]
The mirror 6 reflects the light beam emitted from the beam splitter 5 and emits the light beam to the optical head 7. The mirror 6 reflects the return light from the optical head 7 and emits it to the beam splitter 5.
[0039]
The optical head 7 focuses the light beam emitted from the mirror 6 and irradiates the information beam on the information recording surface of the disk-shaped optical recording medium 51. The light emitted from the optical head 7 to the information recording surface is evanescent light having a spot size equal to or larger than the diffraction limit of the lens and capable of recording and reproducing information.
[0040]
As shown in FIG. 2, the optical head 7 includes an objective lens 8, an SIL (Solid Immersion Lens) 9, a lens folder 10, and an actuator 11.
[0041]
The objective lens 8 focuses the light beam emitted from the laser diode 3 and entered through the collimator lens 4, the beam splitter 5, and the mirror 6, and supplies the light beam to the SIL 9.
[0042]
The SIL 9 is a high refractive index lens having a shape obtained by cutting out a part of a spherical lens into a plane. The SIL 9 enters the light beam supplied from the objective lens 8 from the spherical surface side and focuses the light beam on the central portion of the surface (end surface) opposite to the spherical surface.
[0043]
Further, instead of the SIL 9, a SIM (Solid Image Mirror) having a reflection mirror formed and having the same function as the SIL 9 may be used.
[0044]
The lens folder 10 integrally holds the objective lens 8 and the SIL 9 in a predetermined positional relationship. The SIL 9 is held by the lens folder 10 such that the spherical surface faces the objective lens 8 and the surface (end surface) opposite to the spherical surface faces the information recording surface of the disc-shaped optical recording medium 51.
[0045]
Thus, by disposing the SIL 9 having a high refractive index between the objective lens 8 and the information recording surface of the disc-shaped optical recording medium 51 by the lens folder 10, the numerical aperture larger than the numerical aperture of only the objective lens 8 is provided. Can be obtained. In general, the spot size of the light beam emitted from the lens is inversely proportional to the numerical aperture of the lens. Therefore, the light beam with a much smaller spot size can be obtained by the objective lens 8 and the SIL 9.
[0046]
The actuator 11 operates the lens folder 10 in the focus direction and the tracking direction according to a control voltage output as a control signal from the control system 20.
[0047]
In the optical head 7, the evanescent light is light that has entered the end face of the SIL 9 at an angle equal to or greater than the critical angle and has oozed from the reflection boundary surface of the totally reflected light beam. When the end face of the SIL 9 is located in the near field (near field), which will be described later, from the information recording face of the disc-shaped optical recording medium 51, the evanescent light that has oozed from the end face of the SIL 9 is applied to the information recording face. Will be.
[0048]
Next, the near field will be described. Generally, the near field is a region where the distance d from the light beam emission surface of the lens is d ≦ λ / 2, where λ is the wavelength of light incident on the lens.
[0049]
Considering the optical head 7 and the disk-shaped optical recording medium 51 shown in FIG. 2, the distance (gap) d from the end face of the SIL 9 provided in the optical head 7 to the information recording surface of the disk-shaped optical recording medium 51 is: The area defined as d ≦ λ / 2 by the wavelength λ of the light beam incident on the SIL 9 is the near field. The gap d defined by the distance between the information recording surface of the disc-shaped optical recording medium 51 and the end face of the SIL 9 satisfies d ≦ λ / 2, and evanescent light is recorded on the disc-shaped optical recording medium 51 from the end face of the SIL 9. A state in which the surface oozes out is called a near-field state, and a state in which the gap d satisfies d> λ / 2 and the evanescent light does not ooze out on the information recording surface is called a far-field state.
[0050]
By the way, in the far field state, all light beams incident on the end face of the SIL 9 at an angle equal to or larger than the critical angle are totally reflected and return light. Therefore, as shown in FIG. 3, the total reflection returning light amount in the far field state is a constant value.
[0051]
On the other hand, in the near-field state, a part of the light beam incident on the end face of the SIL 9 at an angle equal to or larger than the critical angle, as described above, is recorded on the end face of the SIL 9, that is, the reflective boundary face, as disc-shaped optical recording as evanescent light. Bleed on the information recording surface of the medium 51. Accordingly, as shown in FIG. 3, the total reflection return light amount of the light beam totally reflected is smaller than in the far field state. As shown in FIG. 3, it can be seen that the total reflection returning light amount in the near-field state decreases exponentially as it approaches the information recording surface of the disc-shaped optical recording medium 51.
[0052]
Therefore, when the position of the end face of the SIL 9 is in the near field state, if the feedback servo is performed using a linear portion where the total reflected return light quantity changes according to the gap length as a gap error signal, the end face of the SIL 9 and the disc-shaped light The gap with the information recording surface of the recording medium 51 can be controlled to be constant. For example, as shown in FIG. 3, if the control is performed so that the total reflection return light amount becomes the control target value P, the gap is kept constant at the distance d.
[0053]
The configuration of the information recording device 50 shown in FIG. 1 will be described again.
[0054]
The condensing lens 52 condenses the return light totally reflected by the end face of the SIL 9 provided in the optical head 7, reflected by the mirror 6, and reflected by the beam splitter 5 to the photodetector 12.
[0055]
The photodetector 12 detects the amount of return light condensed by the condenser lens 52 as a current value. Note that the current value detected by the photodetector 12 has already been converted to DC, and is supplied to the control system 20 as a total reflection return light amount voltage value.
[0056]
The spindle motor 16 is provided with an encoder (not shown) that generates a fixed number of pulse signals called FG signals during one rotation of the spindle motor 16. By counting the FG signal generated from the encoder (not shown), the light beam radiated from the optical head 7 to the disk-shaped optical recording medium 51 changes the circumference of the information recording surface of the disk-shaped optical recording medium 51 at present. It can be understood which position in the direction is being irradiated.
[0057]
An FG signal output from an encoder (not shown) provided in the spindle motor 16 is used as information indicating which position in the circumferential direction of the disk-shaped optical recording medium 51 the optical head 7 is located. The FG signal output from the encoder (not shown) is supplied to the control system 20.
[0058]
The feed base 17 is a base on which the spindle motor 16 as a rotary drive system is mounted, and which moves the disk-shaped optical recording medium 51 mounted on a mounting part (not shown) in the radial direction. The feed table 17 is moved in the radial direction of the disk-shaped optical recording medium 51 by a feed motor 18. By operating the feed table by the feed motor 18, the inter-track movement of the disk-shaped optical recording medium 51 can be performed.
[0059]
The potentiometer 19 is attached to the feed motor 18, and by detecting the rotation angle of the feed motor 18, it is possible to know how much the feed table 17 has moved. The moving amount of the feed base 17 is relatively the same as the moving amount of the optical head 7 in the radial direction of the disk-shaped optical recording medium 51. Therefore, the position of the optical head 7 in the radial direction of the disk-shaped optical recording medium 51 can be determined from the value detected by the potentiometer 19.
[0060]
The detected value obtained from the potentiometer 19 is used as radial position information indicating the position of the optical head 7 in the radial direction of the disk-shaped optical recording medium 51. The radial position information output from the potentiometer 19 is supplied to the control system 20.
[0061]
Next, the control system 20 will be described with reference to FIG. As shown in FIG. 4, the control system 20 controls the gap, which is the distance between the information recording surface of the disc-shaped optical recording medium 51 and the SIL 9 of the optical head 7 based on the FG signal and the radial position information. And a feedback controller 40 that controls the gap based on the total reflected return light amount.
[0062]
The disc-shaped optical recording medium 51 used in the information recording device 50 shown as the first embodiment of the present invention is a removable recording medium that can be mounted on the information recording device 50. Therefore, compared to a recording medium fixed in advance to the apparatus, tilt of the clamp portion, distortion of the disc-shaped optical recording medium 51 due to dust or the like being interposed at the time of clamping, and surface deviation due to disturbance such as axis deviation of the spindle motor 16. The impact is higher.
[0063]
Therefore, the feedforward control unit 30 of the control system 20 is a control unit provided mainly for following the surface shake caused by the disturbance. The feedforward control unit 30 acquires and stores the amount of surface deviation at a predetermined location after the disk-shaped optical recording medium 51 is clamped by the information recording / reproducing device, and reads and follows the amount during a reproducing or recording processing operation. The control is performed to cause the control to be performed.
[0064]
The feed forward control unit 30 includes a memory 31 and a gain unit 32.
[0065]
The memory 31 is a RAM (Random Access Memory) that stores a surface run-out error amount generated after the disk-shaped optical recording medium 51 is clamped to the information recording device 50.
[0066]
With reference to FIG. 5, a mechanism for acquiring the amount of run-out error stored in the memory 31 will be described. The runout error amount is a control voltage value used in the control processing by the feedforward control unit 30 in order to cause the optical head 7 to follow the runout generated on the information recording surface of the disk-shaped optical recording medium 51. It is. When a run-out error signal is applied to the actuator 11 of the optical head 7, the optical head 7 operates so as to follow the run-out occurring on the information recording surface of the disk-shaped optical recording medium 51.
[0067]
As shown in FIG. 5, the information recording device 50 includes a pin after the APC 2, the laser diode 3, and the collimator lens 4 in order to acquire the amount of surface shake error of the disk-shaped optical recording medium 51 stored in the memory 31. It includes a hole 61, a mirror 62, an objective lens 63, a position detection diode (PSD) 64, and a control signal converter 65.
[0068]
The pinhole 61 narrows the light amount of the light beam incident from the collimator lens 4.
[0069]
The mirror 62 reflects the light beam passing through the pinhole 61 and emits the light beam to the objective lens 63.
[0070]
The objective lens 63 condenses the light beam emitted from the mirror 62 and irradiates the information recording surface of the disc-shaped optical recording medium 51 with a spot-shaped light beam.
[0071]
The position detection diode 64 is an optical sensor that can detect the position of a spot-like light as a current value. The position detecting diode 64 is irradiated with return light of the light beam irradiated on the information recording surface of the disc-shaped optical recording medium 51 by the objective lens 63, and detects the position of the irradiated light beam as a current value.
[0072]
The mechanism for acquiring the surface shake error amount in the information processing apparatus 50 shown in FIG. 5 is automatically switched by, for example, mechanically moving the APC 2, the laser diode 3, and the collimator lens 4 shown in FIG. This is realized in such a manner that a light beam emitted from the laser diode 3 passes through the pinhole 61 by an optical method.
[0073]
In the mechanism for acquiring the amount of surface deviation shown in FIG. 5, a method generally called an off-axis method is used. The off-axis method will be described with reference to FIGS.
[0074]
As shown in FIG. 6, for example, when the information recording surface of the disc-shaped optical recording medium 51 is at the position A, when the information recording surface at the position A is irradiated with a light beam through the objective lens 63, the position detecting diode At 64, the position A 'is irradiated with return light, and the spot position of the irradiated return light is detected as a current value.
[0075]
When the information recording surface of the disc-shaped optical recording medium 51 is at the position B, when the information recording surface at the position B is irradiated with a light beam via the objective lens 63, the position detecting diode 64 is moved to the position B '. The return light is irradiated, and the spot position of the irradiated return light is detected as a current value.
[0076]
As described above, the position detecting diode 64 receives the return light of the light beam applied to the disc-shaped optical recording medium 51 in accordance with the difference in the position of the information recording surface of the disc-shaped optical recording medium 51 in the focus direction. Light is applied to different positions of the diode 64. Therefore, by detecting the position of the return light irradiated to the position detection diode 64, it is possible to acquire how much the information recording surface of the disk-shaped optical recording medium 51 has changed in the focus direction. The amount of change in the focus direction detected as a current value by the position detection diode 64 is subjected to a predetermined operation by the control signal conversion unit 65 and converted into a voltage value, and the deviation of the information recording surface of the disk-shaped optical recording medium 51 is reduced. It is possible to obtain a surface error signal indicated by a voltage value.
[0077]
FIG. 7 shows the relationship between the position (position) where the spot of the return light is irradiated on the position detection diode 64 and the surface shake error signal.
[0078]
According to FIG. 7, when the information recording surface of the disc-shaped optical recording medium 51 is located at the position A shown in FIG. 6 and a spot of the return light is detected at the position A ′ of the position detecting diode 64, a surface shake error signal is generated. It indicates “0”, and when a spot of the return light is detected at the position B ′, it is a predetermined amount of the surface shake error signal. That is, the position A of the information recording surface where the spot of the return light is irradiated to the position A ′ of the position detection diode 64 is the position to be controlled by the feedforward control unit 30, and there is a variation from this position. In this case, the surface error signal, which is a control voltage applied to the actuator 11 of the optical head 7, is obtained as a predetermined value.
[0079]
As a method for acquiring the amount of surface deviation error, a generally known method using a Michelson interferometer, a triangulation method, or the like can be used in addition to the off-axis method described above.
[0080]
As described above, the surface error signal detected by the position detection diode 64 and obtained by the processing in the control signal conversion unit 65 is stored in the memory 31 of the feedforward control unit 30.
[0081]
The memory 31 stores a runout error signal for a predetermined radius position and one turn of the disk-shaped optical recording medium 51. As shown in FIG. 8, an error signal for a predetermined radius and one turn of the removable disk-shaped optical recording medium 51 which is mounted on the information recording device 50 with its central portion clamped, as shown in FIG. From the center to the outer periphery.
[0082]
Therefore, at a certain radial position of the disk-shaped optical recording medium 51, if a run-out error signal for one round is acquired and stored in the memory 31, then, if the rate of change is known, the stored run-out error signal is stored. And the rate of change, it is possible to obtain a runout error signal at an arbitrary radial position.
[0083]
Next, a procedure for storing the run-out error signal will be described with reference to the flowchart shown in FIG.
[0084]
As described above, the memory 31 stores the circumferential wobble error signal at a predetermined radial position of the disk-shaped optical recording medium 51. The circumferential error signal stored in the memory 31 is applied to the optical head 7 when the FG signal is output by an encoder (not shown) connected to the spindle motor 16. This is a plane error signal detected and obtained from the control signal converter 65. Therefore, the encoder (not shown) outputs the FG signal, which is a pulse signal, a predetermined number of times each time the spindle motor 16 makes one rotation. Therefore, the FG signal is stored in the memory 31 at a predetermined radial position of the disk-shaped optical recording medium 51. The run-out error signal corresponding to the signal is stored.
[0085]
First, in step ST1, an FG signal is output from an encoder (not shown) attached to the spindle motor 16, and is counted up by an FG counter (not shown).
[0086]
At this time, the runout error signal is continuously obtained from the position detection diode 64 and the control signal converter 65.
[0087]
In step ST2, in response to the FG signal being counted up by the FG counter (not shown), the count value of the FG signal counted by the FG counter (not shown) is used as the address value of the plane error signal to be stored in the memory 31. Stored in the memory 31.
[0088]
Further, a surface error signal acquired from the control signal converter 65 is stored in the memory 31 in correspondence with the address value stored in the memory 31.
[0089]
In step ST3, it is determined whether an FG counter (not shown) has counted the FG signal for one round of the disk-shaped optical recording medium 51. If the FG signal for one rotation has not been counted, the process returns to step ST1, and if the FG signal for one rotation has been counted, the process ends.
[0090]
In this manner, the memory 31 stores the count value of the FG signal as the address value, and associates the address value with the surface error signal at the position where the FG signal is generated in one-to-one correspondence. Will be.
[0091]
The runout error signal stored in the memory 31 is read out in accordance with the value of the FG signal output from an encoder (not shown) attached to the spindle motor 16 during a recording operation in the information recording device 50, and is performed in a subsequent stage. The signal is supplied to the gain unit 32.
[0092]
Next, the gain section 32 of the feedforward control section 30 will be described. The gain unit 32 calculates, for each FG signal, a proportional relationship between the surface error signal shown in FIG. 8 from the surface error signal for one round at a predetermined radial position of the disk-shaped optical recording medium 51 stored in the memory 31. Is calculated by multiplying the gain determined by using the equation (1) to calculate a surface shake error signal at an arbitrary radial position.
[0093]
The gain multiplied by the gain unit 32 will be described. For example, it is assumed that the memory 31 stores a runout error signal for one round of the radius Rm of the disk-shaped optical recording medium 51. The maximum value of the amplitude at the position of the disk-shaped optical recording medium 51 where the largest surface error signal is obtained from the surface error signals stored in the memory 31 is defined as the surface amplitude peak amplitude value β. Further, if the surface shake peak value which is the maximum amplitude of the surface shake at an arbitrary radius Rn of the disk-shaped optical recording medium 51 is γ, the relationship between the radius of the disk-shaped optical recording medium 51 and the surface shake peak amplitude value is shown in FIG. A proportional relationship as shown in FIG. Since the center of the disk-shaped optical recording medium 51 is clamped, no wobble occurs in principle, and the wobble peak amplitude value is “0”.
[0094]
As a result, the surface shake peak amplitude value γ at an arbitrary radius Rn is represented by Expression (1).
[0095]
γ = β × (Rn / Rm) (1)
[0096]
Equation (1) indicates that, by designating an arbitrary radius Rn as a parameter, the surface shake peak amplitude value γ at that radius is obtained.
[0097]
Further, assuming that the face error signal stored in the memory 31 is Vfg, the face error signal Vf at an arbitrary radius Rn can be estimated from the equation (2).
[0098]
Vf = Vfg × γ = Vfg × {β × (Rn / Rm)} (2)
[0099]
In the expression (2), the shake error signal Vfg stored in the memory 31 is multiplied by the shake peak amplitude value γ at an arbitrary radius Rn as a gain. By using the peak amplitude of the surface shake as a gain, it is possible to generate a surface error signal Vf that is proportional to an arbitrary radius Rn and that is a control signal in consideration of the maximum displacement of the surface shake amplitude.
[0100]
At the time of the recording operation in the information recording device 50, the gain unit 32 uses the expression (2) to add the potential error attached to the feed motor 18 to the runout error signal Vfg at the radius Rm supplied from the memory 31. By multiplying the gain obtained from the radial position information output from the meter 19, a runout error signal Vf is generated and supplied to the system controller 46 as a control voltage.
[0101]
Returning to FIG. 4 again, the feedback control unit 40 included in the control system 20 will be described. The feedback control unit 40 includes an adder 41, a comparator 42, a main control unit 43, a sub control unit 44, a control signal switching circuit 45, and a system controller 46.
[0102]
The total reflection return light amount voltage value output from the photodetector 12 described above is supplied to the adder 41 and the comparator 42.
[0103]
The adder 41 compares the control target voltage value for setting the gap to the control target value P with the total reflection return light amount voltage value output from the photodetector 12, and takes a deviation. The control target voltage value is a preset constant voltage or the like.
[0104]
The comparator 42 compares the voltage value of the total reflection return light amount output from the photodetector 12 with a threshold value T1, which is a predetermined voltage value. The threshold value T1 is a value selected so as to satisfy the relationship of the control target value P and T1> P. When the total reflection return light amount voltage value is larger than the threshold value T1, the SIL 9 of the optical head 7 is in the far field state. Conversely, when the total reflection return light amount voltage value is smaller than the threshold value T1, it indicates that the SIL 9 is in the near-field state.
[0105]
Therefore, when the comparator 42 is in the far field state based on the comparison result of the voltage values, for example, the control signal switching circuit 45 switches the control voltage value generated by the sub-control unit 44 so that the control voltage value is selected. When the signal “0” is output and the state is in the near field state, the control signal switching circuit 45 sends, for example, the switching signal “1” to the control signal switching circuit 45 so that the control voltage value generated by the main control unit 43 is selected. Is output.
[0106]
The main control unit 43 generates a control signal Vg which is a control voltage for bringing the gap d closer to the control target value P when the SIL 9 is in the near field state. The main control unit 43 includes, for example, a phase compensation filter designed based on the frequency response, and generates a control signal Vg, which is a control voltage, from the deviation calculated by the adder 41.
[0107]
The sub-controller 44 generates a control signal Vh that causes the SIL 9 of the optical head 7 to approach the information recording surface of the disk-shaped optical recording medium 51 to a distance where the optical head 7 is in a near-field state.
[0108]
The control signal switching circuit 45 outputs a control signal Vh generated by the sub-control unit 44 or outputs a control signal Vg generated by the main control unit 43 according to a switching signal output from the comparator 42. I do.
[0109]
The system controller 46 is a control unit that controls the control system 20 in an integrated manner. The system controller 46 operates the feedforward control unit 30 and the feedback control unit 40 to generate control signals, and the control signals generated by each control unit. Is appropriately supplied to the actuator 11 of the optical head 7.
[0110]
Next, an information reproducing apparatus 50 'shown as a second embodiment of the present invention will be described with reference to FIGS.
[0111]
The information reproducing device 50 'reproduces predetermined information recorded on the disk-shaped optical recording medium 51. The information reproducing apparatus 50 'controls the laser diode 3 so that the APC 2 emits a laser beam having a constant power during reproduction, and reproduces the information from the return light of the light beam applied to the disc-shaped optical recording medium 51. Except for acquiring signals, the operation is exactly the same as that of the information recording device 50, such as control by the control system 20. Therefore, the same reference numerals are given to the respective functional units, and description thereof will be omitted. In addition, the mechanism for acquiring the amount of surface shake error stored in the memory 31 of the information recording device 50 described with reference to FIG.
[0112]
There are two methods for obtaining a reproduction signal from the return light, a method using a difference in frequency band between the reproduction signal and the gap error signal shown in FIG. 11, and a method using a difference in polarization plane shown in FIG.
[0113]
In the method of obtaining a reproduction signal based on a difference in frequency band, a band separation filter 13 is provided downstream of the photodetector 12 as shown in FIG. The band separation filter 13 separates and extracts a reproduction signal, which is information to be reproduced, and a gap error signal used for gap control from the detected value of the return light detected by the photodetector 12. The gap error signal is supplied to the control system 20 as in the case of the information recording device 50.
[0114]
In the method of acquiring a reproduction signal by a difference in polarization plane, the polarization beam splitter 14 is provided between the condenser lens 52 and the photodetector 12, as shown in FIG. The return light condensed by the condenser lens 52 is transmitted and reflected by the polarization beam splitter 14 due to the difference in the polarization plane. The return light transmitted by the polarization beam splitter 14 is detected by the photodetector 12 similarly to the information recording device 50, and is supplied to the control system 20 as a gap error signal. The return light reflected by the polarization beam splitter 14 is detected by the photodetector 15 via the condenser lens 53 and becomes a reproduced signal.
[0115]
Next, the control operation of the optical head 7 by the control system 20 will be described with reference to the flowchart shown in FIG.
[0116]
In step ST11, the FG signal and the radial position information are supplied to the feedforward control unit 30 of the control system 20.
[0117]
In step ST12, the control system 20 operates the feedforward control unit 30 and stops the operation of the feedback control unit 40. Thereby, the feedforward control by the feedforward control unit 30 is executed.
[0118]
In step ST <b> 13, the gain unit 32 of the feedforward control unit 30 reads out a surface error signal corresponding to the FG signal from the memory 31.
[0119]
In step ST14, the gain unit 32 multiplies the control signal Vf by a predetermined gain based on the above-described equation (2) based on the radial error information read from the memory 31 and the supplied radial position information. Generate. The generated control signal Vf is supplied to the system controller 46.
[0120]
In step ST15, the system controller 46 applies the control signal Vf generated by the feedforward control unit 30 to the actuator 11 of the optical head 7, and performs feedforward control.
[0121]
In step ST16, the system control unit 20 holds the control signal Vf applied to the actuator 11, controls to keep applying the control signal Vf, and stops the operation of the feedforward control unit 30. After stopping the operation of the feedforward control unit 30, the system control unit 20 subsequently operates the feedback control unit 40.
[0122]
In step ST17, the feedback control unit 40 causes the comparator 42 to compare the total reflection return light amount voltage value detected by the photodetector 12 with the threshold value T1. When the comparator 42 determines that the total reflection return light amount voltage value is larger, the control signal switching circuit 45 outputs a switching signal such that the control signal Vh generated by the sub control unit 44 is output to the system controller 46. Is output, and the process proceeds to step ST18.
[0123]
If the comparator 42 determines that the threshold value T1 is larger, the control signal Vg generated by the main control unit 43 outputs a switching signal to the system controller 46 to the control signal switching circuit 45. Then, the process proceeds to step ST19.
[0124]
As described above, when the total reflection return light amount voltage value is larger than the threshold value T1, it indicates that the SIL 9 is in the far field state, and when the total reflection return light amount voltage value is smaller than the threshold value T1, the SIL 9 is near field value. It is in the state.
[0125]
In step ST18, the feedback control unit 40 outputs the control signal Vh generated by the sub control unit 44 to the system controller 46 via the control signal switching circuit 45.
[0126]
Further, the system controller 46 outputs the control signal Vh generated by the sub-controller 44 in addition to the control signal Vf generated by the feed-forward controller 30 and applied while being held by the actuator 12 of the optical head 7. Apply. That is, the control signal V supplied to the actuator 12 of the optical head 7 has the following value.
[0127]
V = Vf + Vh
[0128]
This step ST18 is repeatedly executed until the total reflection return light amount detected by the photodetector 12 becomes smaller than the threshold value T1 in the determination step of step ST17.
[0129]
In step ST19, in response to the total reflection return light amount voltage value becoming smaller than the threshold value T1, the control signal Vh 'of the sub control unit 44 at that time is held, and the main control unit 43 Is switched so that the control signal Vg is output. The control signal Vg passes through the control signal switching circuit 45 and is supplied to the system controller 46.
[0130]
The system controller 46 includes, in addition to the control signal Vf generated by the feedforward control unit 30 and applied to the actuator 11 of the optical head 7 and applied thereto, a control signal Vh ′ held by the sub-control unit 44; The control signal Vg generated by the main control unit 43 is applied. That is, the control signal V supplied to the actuator 12 of the optical head 7 has the following value.
[0131]
V = Vf + (Vg + Vh ')
[0132]
The hold voltage Vh ′ of the sub-control unit 44 may be held during control, or the hold voltage of the sub-control unit 44 may be copied to the main control unit 43 when switching to the main control unit 43. Alternatively, the hold voltage of the sub control unit 44 may be released, and control may be performed only by the main control unit 43.
[0133]
As described above, the two-step control by the two control units of the feedforward control unit 30 and the feedback control unit 40 included in the system control unit 20 pulls the total reflection return light amount detected by the photodetector 12 into the control target value P. The gap d, which is the distance between the end face of the SIL 9 of the optical head 7 and the information recording surface of the disc-shaped optical recording medium 51, can be controlled to be constant.
[0134]
Further, when the disc-shaped optical recording medium 51 is mounted on the information recording device 50 or the information reproducing device 50 ', the outer peripheral portion can be clamped without clamping the center portion of the disc-shaped optical recording medium 51, When the front surface is clamped, as shown in FIGS. 8 and 10, the radial position of the disk-shaped optical recording medium 51 does not have a proportional relationship with the peak amplitude of the runout at the radial position.
[0135]
Therefore, in such a case, the control system 20 of the information recording device 50 and the information reproducing device 50 'is changed to a control system 20' having a feedforward control unit 30 'as shown in FIG. This can be dealt with by acquiring a runout error signal for the entire information recording surface of the recording medium 51 in advance and storing the radial position information and the FG signal in the memory 31 as addresses.
[0136]
The feedforward control unit 30 'reads out a runout error signal from the memory 31 based on the radial position information and the FG signal, and executes feedforward control. The control in the feedforward control unit 20 is exactly the same as the control method in the control system 20 shown in FIG. 4 described above.
[0137]
Therefore, in the information recording device 50 and the information reproducing device 50 ′ including the control system 20 ′ instead of the control system 20, similarly, the end surface of the SIL 9 of the optical head 7 and the information recording surface of the disc-shaped optical recording medium 51 are different. Can be controlled such that the predetermined gap d is constant.
[0138]
In the information recording device 50 shown as the first embodiment of the present invention and the information reproducing device 50 'shown as the second embodiment, the feed base 17 is moved by the feed motor 18 to the disc-shaped optical recording medium. The movement between the tracks is performed by moving the track 51 in the radial direction, and the radial position information is obtained by the potentiometer 19 that detects the rotation angle of the feed motor 18.
[0139]
In the information recording device 50 and the information reproducing device 50 ′, an optical pickup is configured by the laser diode 3, the collimator lens 4, the beam splitter 5, the mirror 6, the optical head 7, the condensing lens 52, and the photodetector 12, and the disc-shaped optical recording is performed. The movement of the medium 51 between tracks may be performed by the optical pickup. In such a case, the radial position information may be obtained by installing a potentiometer on a linear motor or the like that moves the optical pickup between tracks.
[0140]
The present invention is applied to an information recording device 60 shown in FIG. 15 as a third embodiment. The information recording device 60 mounts a removable disk-shaped optical recording medium 51 similarly to the information recording device 50, and records information by irradiating the mounted disk-shaped optical recording medium 51 with evanescent light detected in the near field. I do.
[0141]
The information recording device 60 has a mechanism for installing a polarization beam splitter 70 in place of the mirror 6 of the information recording device 50 shown in FIG. 1 and detecting a surface error signal of the disk-shaped optical recording medium 51 shown in FIG. And a control system 80 is provided in place of the control system 20.
[0142]
The relative position between the objective lens 8 of the optical head 7 and the SIL 9 is fixed, and the relative position between the objective lens 63 and the objective lens 8 and the SIL 9 of the optical head 7 is also fixed. Therefore, by performing servo control based on a surface shake error signal detected by the objective lens 63, not only the objective lens 63 but also the objective lens 8 and the SIL 9 follow the information recording surface of the disk-shaped optical recording medium 51. be able to.
[0143]
In the information recording device 60 according to the third embodiment, the same reference numerals are given to the functional units other than the polarization beam splitter 70 and the control system 80 in the information recording device 50 described with reference to FIGS. Since this is exactly the same as that described above, a detailed description of the corresponding portions will be omitted.
[0144]
The light beam emitted from the laser diode 3 and transmitted through the beam splitter 5 via the collimator lens 4 is emitted to the polarization beam splitter 70.
[0145]
The polarization beam splitter 70 reflects and transmits the light beam emitted from the beam splitter 5 depending on the difference in polarization components. For example, the polarizing beam splitter 70 reflects the P-polarized component of the light beam and transmits the S-polarized component. Specifically, the polarizing beam splitter 70 reflects the light beam emitted from the beam splitter 5 and supplies the light beam to the optical head 7, transmits the light beam emitted from the beam splitter 5, and transmits the light beam emitted from the beam splitter 5 to the pinhole 61 and the mirror 62. Is supplied to the objective lens 63 via
[0146]
The return light of the light beam supplied to the optical head 7 and applied to the information recording surface of the disc-shaped optical recording medium 51 is reflected by the polarization beam splitter 70, reflected by the beam splitter 5, and It is detected by the photo detector 12 and supplied to the control system 80 as a gap error signal.
[0147]
The return light of the light beam supplied to the objective lens 63 and applied to the information recording surface of the disc-shaped optical recording medium 51 is detected by the position detection diode 64 and converted into a surface shake error signal by the control signal conversion unit 65. It is supplied to the control system 80.
[0148]
The control system 80 operates the optical head 7 based on the surface error signal or the total reflection return light amount as shown in FIG. 16 so as to reduce the gap between the SIL 9 and the information recording surface of the disk-shaped optical recording medium 51. The control unit includes a servo control unit 90 for controlling run-out and a gap servo control unit 40 '.
[0149]
The runout servo control unit 90 includes an adder 91 and a controller 92.
[0150]
The adder 91 is provided with a surface error signal voltage value detected by the position detection diode 64 and converted into a control voltage value by the control signal converter 65, and a reference voltage value of the surface error signal which becomes the control target value Q. And supplies it to the controller 92.
[0151]
The controller 92 generates a control signal Vi based on the surface error signal supplied from the adder 91 and supplies the control signal Vi to the system controller 46 ′. Further, the controller 92 compares the absolute value of the surface error signal supplied from the adder 91 with the threshold value TH2, and notifies the system controller 46 ′ of the comparison result. The threshold value TH2 is a surface shake error signal detected when the end surface of the SIL 9 is at the boundary between the far field state and the near field state. FIG. 17 shows the threshold value TH2.
[0152]
If the plane error signal supplied from the adder 92 is larger than the threshold TH2, the control by the plane error signal is compensated. If the plane error signal supplied from the adder 92 is smaller than the threshold TH2, The control by the gap servo control unit 40 'using the total reflection return light quantity can be performed.
[0153]
The gap servo control unit 40 ′ includes a system controller 46 ′ to which a control signal Vi supplied from a controller 92 of the surface deviation servo control unit 90 is supplied, instead of the system controller 46 included in the feedback control unit 40. The configuration is exactly the same as that of the feedback control unit 40 except for the above.
[0154]
The total reflection return light amount detected by the photodetector 12, that is, the total reflection return light amount voltage value is supplied to the adder 41 and the comparator.
[0155]
The main controller 43, based on a comparison result of the threshold value TH1 for determining whether the end face of the SIL 9 is located in the far field or the near field by the comparator 42 and the total reflection return light amount voltage, Alternatively, the sub control unit 44 is selected, and the control voltage generated by the selected control unit is supplied to the system controller 46 '.
[0156]
When the main control unit 43 is selected, feedback control in the near field using the total reflection return light amount voltage value is performed. When the sub control unit 44 is selected, it indicates that the SIL 9 is in the far field. Thus, the control for causing the optical head 7 to approach the near field state slowly is executed.
[0157]
The system controller 46 ′ is a control unit that controls the control system 80 in a comprehensive manner. The system controller 46 ′ operates the runout servo control unit 90 and the gap servo control unit 40 ′ to generate control signals, and the control units generate the control signals. The supplied control signal is appropriately supplied to the actuator 11 of the optical head 7. The system controller 46 ′ stops or operates the servo control in the face-to-face servo control unit 90 or operates the gap servo in accordance with the comparison result between the face-to-face error signal output from the controller 92 and the threshold value TH2. The servo control of the control unit 40 'is stopped or operated.
[0158]
When the surface error signal supplied from the adder 91 is larger than the threshold value TH2, the gap servo control unit 40 'is stopped, the surface servo control unit 90 is operated, and the surface error signal becomes smaller than the threshold value TH2. Operates the gap servo control unit 40 'and stops the runout servo control unit 90.
[0159]
Next, an information reproducing apparatus 60 'shown as a fourth embodiment of the present invention will be described with reference to FIGS.
[0160]
The information reproducing device 60 'reproduces predetermined information recorded on the disk-shaped optical recording medium 51. The information reproducing apparatus 60 ′ controls the laser diode 3 so that the APC 2 emits a laser beam having a constant power during reproduction, and reproduces the information from the return light of the light beam applied to the disc-shaped optical recording medium 51. Except for acquiring a signal, the operation is exactly the same as that of the information recording device 60, such as control by the control system 80. Therefore, the same reference numerals are given to the respective functional units, and description thereof will be omitted.
[0161]
As a method of acquiring a reproduction signal from the return light, there are a method using a difference in frequency band between the reproduction signal and the gap error signal shown in FIG. 18, and a method using a difference in polarization plane shown in FIG.
[0162]
In the method of acquiring a reproduced signal based on a difference in frequency band, a band separation filter 13 is provided downstream of the photodetector 12, as shown in FIG. The band separation filter 13 separates and extracts a reproduction signal, which is information to be reproduced, and a gap error signal used for gap control from the detected value of the return light detected by the photodetector 12. The gap error signal is supplied to the control system 80 as in the case of the information recording device 60.
[0163]
In the method of obtaining a reproduction signal based on a difference in polarization plane, the polarization beam splitter 14 is provided between the condenser lens 52 and the photodetector 12, as shown in FIG. The return light condensed by the condenser lens 52 is transmitted and reflected by the polarization beam splitter 14. The return light transmitted by the polarization beam splitter 14 is detected by the photodetector 12 similarly to the information recording device 50, and is supplied to the control system 80 as a gap error signal. The return light reflected by the polarization beam splitter 14 is detected by the photo detector 15 and becomes a reproduction signal.
[0164]
Subsequently, a control operation of the optical head 7 by the control system 80 will be described using a flowchart shown in FIG.
[0165]
In step ST31, the light beam emitted from the laser diode 3 is applied to the information recording surface of the disk-shaped optical recording medium 51, and the reflected return light is detected by the position detection diode 64. The run-out error signal converted into the voltage value by the control signal conversion unit 65 is supplied to the run-out servo control unit 90 of the control system 80.
[0166]
In step ST32, the control system 80 operates the runout servo control unit 90 and stops the operation of the gap servo control unit 40 '. Thereby, the servo control by the surface deviation servo control unit 90 is started.
[0167]
In step ST33, the controller 92 generates a control voltage Vi which eliminates a deviation between the surface error signal calculated by the adder 91 and the control target voltage value, and supplies the control voltage Vi to the system controller 46 '.
[0168]
In step ST34, the system controller 46 'applies the control signal Vi generated by the surface shake servo controller 90 to the actuator 11 of the optical head 7, and performs the surface shake servo control.
[0169]
In step ST35, the system control unit 80 determines whether or not the absolute value of the surface error signal has become smaller than the threshold value TH2. If the face error signal is smaller than the threshold value TH2, the process proceeds to step ST36. If the threshold value TH2 is larger than the face error signal, the process returns to step ST31.
[0170]
In step ST36, the system control unit 80 holds the control signal Vi applied to the actuator 11, controls to keep applying the control signal Vi, and stops the operation of the face-running servo control unit 90. After stopping the operation of the runout servo control unit 90, the system control unit 20 subsequently operates the gap servo control unit 40 '.
[0171]
In step ST37, the gap servo control unit 40 'causes the comparator 42 to compare the total reflection return light amount voltage value detected by the photodetector 12 with the threshold value T1. When the comparator 42 determines that the total reflection return light amount voltage value is larger, the comparator 42 outputs a switching signal such that the control signal Vh generated by the sub control unit 44 is output to the system controller 46 ′. And the process proceeds to step ST38.
[0172]
When the comparator 42 determines that the threshold value T1 is larger than the threshold value T1, the control signal Vg generated by the main control unit 43 is transmitted to the control signal switching circuit 45 such that the switching signal is output to the system controller 46 ′. Is output, and the process proceeds to step ST39.
[0173]
As described above, when the total reflection return light amount voltage value is larger than the threshold value T1, it indicates that the SIL 9 is in the far field state, and when the total reflection return light amount voltage value is smaller than the threshold value T1, the SIL 9 is near field value. It is in the state.
[0174]
In step ST38, the gap servo controller 40 'outputs the control signal Vh generated by the sub controller 44 to the system controller 46' via the control signal switching circuit 45.
[0175]
Further, the system controller 46 ′ generates the control signal Vi generated by the sub-control unit 44 in addition to the control signal Vi generated by the surface-running servo control unit 90 and held and applied to the actuator 11 of the optical head 7. Vh is applied. That is, the control signal V supplied to the actuator 11 of the optical head 7 has the following value.
[0176]
V = Vi + Vh
[0177]
The process of step ST38 is repeatedly performed until the total reflection return light amount detected by the photodetector 12 becomes smaller than the threshold value T1 in the determination process of step ST37.
[0178]
In step ST39, in response to the total reflection return light amount voltage value becoming smaller than the threshold value T1, the control signal Vh 'of the sub control unit 44 at that time is held, and the main control unit 43 Is switched so that the control signal Vg is output. The control signal Vg passes through the control signal switching circuit 45 and is supplied to the system controller 46 '.
[0179]
The system controller 46 ′ generates a hold control signal Vh ′ of the sub control unit 44 in addition to the control signal Vi generated by the surface-running servo control unit 90 and applied to the actuator 11 of the optical head 7. Then, the control signal Vg generated by the main control unit 43 is applied. That is, the control signal V supplied to the actuator 11 of the optical head 7 has the following value.
[0180]
V = Vi + (Vg + Vh ')
[0181]
The hold voltage Vh ′ of the sub-control unit 44 may be held during control, or the hold voltage of the sub-control unit 44 may be copied to the main control unit 43 when switching to the main control unit 43. Alternatively, the hold voltage of the sub control unit 44 may be solved, and the control may be performed only by the main control unit 43.
[0182]
As described above, the two-step control by the two control units of the surface shake servo control unit 90 and the gap servo control unit 40 'included in the system control unit 80 controls the total reflection return light amount detected by the photodetector 12 to the control target value. It can be controlled so that the gap d, which is the distance between the end face of the SIL 9 of the optical head 7 and the information recording surface of the disc-shaped optical recording medium 51, becomes constant.
[0183]
Subsequently, the information recording device 50 shown as the first embodiment of the present invention, the information reproducing device 50 ′ shown as the second embodiment, the information recording device 60 shown as the third embodiment, A rotation control system for controlling the operation of the spindle motor 16 provided in the information reproducing apparatus 60 'shown as the fourth embodiment will be described.
[0184]
This rotation control system has exactly the same configuration when applied to any of the information recording device 50, the information reproducing device 50 ', the information recording device 60, and the information reproducing device 60'. Therefore, as shown in FIG. Description will be made using the information recording device 50 shown as the embodiment.
[0185]
As shown in FIG. 22, the rotation control system 100 includes a frequency loop control unit 110, a PLL control unit 120, a system controller 101 that controls the frequency loop control unit 110 and the PLL control unit 120, and a frequency loop control unit. The control unit 110 includes an adder 102 that adds the control signals generated by the PLL control unit 120. The rotation control system 100 stabilizes the rotation of the spindle motor 16 by the frequency loop control unit 110 and the PLL control unit 120.
[0186]
The frequency loop control unit 110 includes an FV converter 111, an adder 112, and a controller 113. The frequency loop control unit 110 is operated before the phase control is performed by the PLL control unit 120 and locks the rotation frequency of the spindle motor 16.
[0187]
The FV converter 111 converts the FG signal supplied from the encoder 130 into a voltage Vfv and outputs the voltage to the adder 112.
[0188]
The adder 112 calculates the frequency loop error signal Ef by adding the reference voltage Vref and a value obtained by adding a negative sign to the voltage Vfv output from the FV converter 111.
[0189]
The controller 113 generates a frequency loop control voltage Vr such that the frequency loop error signal Ef calculated by the adder 112 becomes 0, and supplies the frequency loop control voltage Vr to the spindle motor 16 via the system controller 101 and the adder 102.
[0190]
The PLL control unit 120 includes a phase comparator 121 and a controller 122. The PLL control unit 120 is operated after the frequency of the spindle motor 16 is locked by the frequency loop control unit 110, and locks the phase of the spindle motor 16 by phase comparison.
[0191]
In the phase comparison period 121, the phase of the FG signal supplied from the encoder 130 is compared with the phase of a reference clock, which is a signal having the same frequency as the FG signal, to obtain a phase difference (phase error signal Pe).
[0192]
The controller 122 generates a control voltage Vp for rotating the spindle motor 16 so that the phase error signal Pe obtained by the phase comparator 121 becomes zero, and outputs the control voltage Vp via the system controller 101 and the adder 102. To supply.
[0193]
When the control operation is shifted to the PLL control unit 120, the frequency control voltage Vr generated by the frequency loop control unit 110 is held and continuously applied to the spindle motor 16. Therefore, when the control voltage Vp is generated by the PLL control unit 120, the spindle motor control voltage Vs finally applied to the spindle motor 16 becomes Vs = Vr + Vp.
[0194]
When the frequency loop control is performed by the above-described frequency loop control unit 100 so as to achieve a predetermined rotation speed, the frequency control voltage Vr exhibits characteristics as shown in FIG. 23 over time.
[0195]
Immediately after the start of the frequency loop control, the spindle motor 16 requests a voltage value higher than the voltage required in the steady state due to the inertia of continuing the stopped state. Therefore, when the spindle motor 16 starts rotating, the above-mentioned voltage value becomes an excessively large voltage due to the inertia of trying to continue the rotating state, and has an overshoot as shown in FIG.
[0196]
Due to the excessive frequency control voltage Vr supplied during the initial rotation of the disk-shaped optical recording medium 51, the disk-shaped optical recording medium 51 is rapidly accelerated. As a result, the rotation axis of the disk-shaped optical recording medium 51 is shaken, and the disk is shaken, and as a result, the information recording surface is shaken.
[0197]
When the PLL control is performed by the above-described PLL control unit 120, the phase error Pe, which is the phase difference, shows a characteristic as shown in FIG. A control voltage according to the phase error Pe is applied to the spindle motor 16. Therefore, as shown in FIG. 24, if the phase error Pe fluctuates greatly until the steady state is reached, the rotation speed of the spindle motor 16 will be rapidly accelerated and decelerated, as in the frequency loop control. The rotation axis of the disk-shaped optical recording medium 51 is shaken, and the disk is shaken, resulting in the information recording surface being shaken.
[0198]
This is because the SIL9 and the disc are used in a device that performs recording and reproduction using evanescent light in the near-field state, such as the information recording device 50, the information reproducing device 50 ′, the information recording device 60, and the information reproducing device 60 ′. Since the gap between the information recording surface of the optical recording medium 51 and the gap is on the order of several tens of nanometers, the runout caused by the control by the rotation control system 100 acts as a large disturbance.
[0199]
Therefore, the control operation of the control system 20 included in the information recording device 50 and the information reproducing device 50 ′, and the control operation of the control system 80 included in the information recording device 60 and the information reproducing device 60 ′ are controlled by the spindle motor 16 of the rotation control system 100. Needs to be started at the time when the runout caused by the rotation control does not affect the gap servo control.
[0200]
Therefore, as shown in FIG. 24, for the phase error Pe, a threshold value TH3 that indicates a phase error Pe that does not affect the gap servo control in the near-field state due to the surface shake generated by the rotation control system 100 is set. Set.
[0201]
Accordingly, in the PLL control by the PLL control unit 120, if the phase error Pe becomes the threshold value TH3, the control system 20, the information recording device 60, and the information reproduction device 50 'if the information recording device 50 and the information reproduction device 50' are used. In the case of the device 60 ′, by causing the operation of the control system 80 to be started, it is possible to avoid runout caused by the rotation control system 100.
[0202]
The timing at which the control by the rotation control system 100 and the control system 20 or the control system 80 is executed will be described with reference to the flowchart shown in FIG.
First, rotation control of the spindle motor 16 by the rotation control system 100 is executed. The system controller 101 controls the frequency loop control unit 110 to execute frequency loop control until the spindle motor 16 reaches a predetermined rotation speed (step ST41), and determines whether the rotation speed has reached the predetermined rotation speed (step ST42). ).
[0203]
When the spindle motor 16 has reached the predetermined number of revolutions, the frequency loop control voltage Vr is held and the PLL control unit 120 is operated (step ST42). If the spindle motor 16 has not reached the predetermined number of revolutions, the process from step ST41 is repeated.
[0204]
Next, the system controller 101 causes the PLL control unit 120 to execute the PLL control until the phase error Pe becomes smaller than the preset threshold TH3 (step ST43), and determines that the phase error Pe becomes smaller than the threshold TH3. In response (step ST44), the control by the above-described control system 20 is started (step ST45).
[0205]
Thus, the information recording device 50 shown as the first embodiment, the information reproducing device 50 'shown as the second embodiment, the information recording device 60 shown as the third embodiment, In an apparatus that performs recording or reproduction using the evanescent light detected in the near field, such as the information reproducing apparatus 60 ′ described in the embodiment, the surface deviation generated by the rotation control system 100 affects the gap servo control. Is stopped, the control by the control system 20 or the control system 80 is executed.
[0206]
In each of the information recording devices described as the first and third embodiments and the information reproducing devices described as the second and fourth embodiments, the arrangement of the beam splitter, the collimator lens, and the like is appropriately determined. Can be changed.
[0207]
【The invention's effect】
As is clear from the above description, according to the present invention, after the first control means suppresses the surface deviation of the optical recording medium, the second control means controls the information recording surface of the optical recording medium and the near-field light. Feedback control is performed so that the distance to the emission device is kept constant in the near field.
[0208]
As a result, a DC gain for each control means can be appropriately secured, so that recording quality and reproduction using near-field light such as deterioration of reproduction quality due to insufficient DC gain and breakdown of the near-field state are critical. Errors can be prevented.
[0209]
In addition, since the first control means suppresses the deviation of the surface of the optical recording medium, it is possible to perform good recording and reproduction of the optical recording medium while maintaining the removable property of the optical recording medium.
[0210]
Further, according to the present invention, the gap servo control is started after the operation of the rotation control system of the disk-shaped optical recording medium is in a steady state, so that the gap servo control can be executed reliably and stably.
[Brief description of the drawings]
FIG. 1 is a diagram for describing a configuration of an information recording device shown as a first embodiment of the present invention.
FIG. 2 is a diagram for explaining an optical head included in the information recording device.
FIG. 3 is a diagram for explaining a relationship between a return light amount and a gap distance.
FIG. 4 is a diagram for describing a configuration of a control system of the information recording apparatus shown as the first embodiment.
FIG. 5 is a diagram for explaining a mechanism for acquiring a surface shake amount of the optical recording medium in the information recording apparatus.
FIG. 6 is a diagram for describing detection of a surface shake amount using an off-axis method in the information recording apparatus.
FIG. 7 is a diagram showing a surface shake error signal and a position of an optical recording medium in the information recording apparatus.
FIG. 8 is a first diagram showing a relationship between a radius of an optical recording medium and a surface shake peak amplitude value in the information recording apparatus.
FIG. 9 is a flowchart for explaining the operation of the information recording apparatus when storing a run-out signal in a memory.
FIG. 10 is a second diagram showing a relationship between a radius of an optical recording medium and a peak amplitude value of a runout in the information recording apparatus.
FIG. 11 is a first diagram for describing a configuration of an information reproducing apparatus shown as a second embodiment of the present invention.
FIG. 12 is a second diagram for describing the configuration of the information reproducing apparatus shown as the second embodiment of the present invention.
FIG. 13 is a flowchart for explaining a control operation by a control system provided in the information recording device shown as the first embodiment of the present invention and the information reproducing device shown as the second embodiment.
FIG. 14 is a diagram for explaining another configuration of the control system.
FIG. 15 is a diagram for describing a configuration of an information recording device shown as a third embodiment of the present invention.
FIG. 16 is a diagram for explaining a configuration of a control system of the information recording apparatus.
FIG. 17 is a diagram for explaining a threshold set by the control system of the information recording apparatus.
FIG. 18 is a first diagram illustrating a configuration of an information reproducing apparatus shown as a fourth embodiment of the present invention.
FIG. 19 is a second diagram for describing the configuration of the information reproducing apparatus shown as the fourth embodiment of the present invention.
FIG. 20 is a flowchart for explaining a control operation by a control system provided in the information recording device shown as the third embodiment of the present invention and the information reproducing device shown as the fourth embodiment of the present invention.
FIG. 21 is a diagram schematically showing a rotation control system mounted on the information recording apparatus shown as the first embodiment.
FIG. 22 is a diagram for describing a configuration of a rotation control system.
FIG. 23 is a diagram illustrating characteristics of a frequency control voltage generated by the frequency loop control unit.
FIG. 24 is a diagram illustrating characteristics of a phase error signal in a PLL control unit.
FIG. 25 is a flowchart for describing control in the rotation control system and operation timing with the control system.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 information source, 2 APC, 3 laser diode, 4 collimator lens, 5 beam splitter, 6 mirror, 7 optical head, 8 objective lens, 9 SIL, 11 actuator, 12 photodetector, 13 low-pass filter, 14 polarization beam splitter, 15 Photodetector, 16 spindle motor, 17 feed base, 18 feed motor, 19 potentiometer, 20 control system, 50 information recording device, 50 'information reproducing device, 51 disk-shaped optical recording medium

Claims (76)

Mounting means for mounting a removable disk-shaped optical recording medium;
Rotation driving means for rotating the disc-shaped optical recording medium mounted on the mounting means at a predetermined number of rotations,
Pulse signal generating means for generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means;
Counting means for counting N pulse signals generated by the pulse signal generating means;
Storage means for storing the amount of runout of a predetermined radius detected at the timing when the pulse signal is generated by the pulse signal generation means, in association with the count value by the counting means,
A light source for emitting a light beam of a predetermined wavelength modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium,
A light beam emitted from the light source is condensed, and when placed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, the converged light beam is emitted to the information recording surface as near-field light. Near-field light emitting means,
Radial position information detecting means for detecting radial position information indicating the radial position of the information recording surface of the disc-shaped optical recording medium to which the near-field light emitting means is irradiating the light beam,
Gain generating means for generating a predetermined gain corresponding to the radial position information detected by the radial position information detecting means,
In accordance with the count value of the pulse signal counted by the counting means, a surface blur amount reading means for reading the surface blur amount stored in the storage means,
A control signal is generated by multiplying the surface shake amount read by the surface shake amount reading unit by the predetermined gain generated by the gain generating unit, and the near-field light emitting unit is controlled by the surface shake amount. First control means for controlling so as to follow
Return light amount detection means for detecting the return light amount of the near-field light emitted to the information recording surface,
A second control unit that controls the near-field light emitting unit to maintain a predetermined distance within the near field with respect to the information recording surface, based on a linear characteristic of a returning light amount of the near-field light detected by the returning light amount detecting unit. An information recording apparatus, comprising: When the return light amount detected by the return light amount detection means is larger than a predetermined threshold value, the near-field light emitting means is controlled to be arranged in a near field with respect to the information recording surface of the disk-shaped optical recording medium. 2. The information recording apparatus according to claim 1, further comprising control means. Optical means for condensing the light beam emitted from the light source and emitting the information beam to the information recording surface of the disc-shaped optical recording medium;
Surface deviation detection means for detecting the surface deviation of the disc-shaped optical recording medium from the return light of the light beam emitted by the optical means,
The storage means stores, at the timing at which a pulse signal is generated by the pulse signal generation means, the amount of surface shake at a predetermined radius of the disk-shaped optical recording medium detected by the surface shake amount detection means, by the counting means. 2. The information recording apparatus according to claim 1, wherein the information is stored in association with the count value. The storage means stores an amount of runout at a radius Rm of the disc-shaped optical recording medium,
The gain generating means calculates the gain at the radial position Rn detected by the radial position information detecting means by β × (Rn / Rm)
The information recording apparatus according to claim 1, wherein the information recording apparatus generates the information. 2. The information recording apparatus according to claim 1, wherein the near-field light emitting unit has a solid immersion lens (SIL). 2. The information recording apparatus according to claim 1, wherein the near-field light emitting means has a SIM (Solid Immersion Mirror). A mounting process of mounting a removable disk-shaped optical recording medium,
A rotation driving step of rotating the mounted disk-shaped optical recording medium at a predetermined rotation speed,
A pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving step;
A counting step of counting N pulse signals generated in the pulse signal generating step;
A storage step of storing a surface shake amount of a predetermined radius detected at a timing when a pulse signal is generated in the pulse signal generation step in a storage unit in association with the count value in the counting step;
A light beam having a predetermined wavelength, which is modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium and emitted from the light source, is condensed and arranged in a near field with respect to the information recording surface of the disc-shaped optical recording medium. Near-field light emission means, the near-field light emission step of emitting the focused light beam to the information recording surface as the near-field light,
A radial position information detecting step of detecting radial position information indicating a radial position of an information recording surface of the disc-shaped optical recording medium on which the near-field light emitting unit irradiates the light beam;
A gain generating step of generating a predetermined gain corresponding to the radial position information detected by the radial position information detecting step,
In accordance with the count value of the pulse signal counted in the counting step, a surface blur amount reading step of reading the surface blur amount stored in the storage step,
A control signal is generated by multiplying the surface shake amount read in the surface shake amount reading step by the predetermined gain generated in the gain generation step, and the near-field light emitting unit is controlled by the surface shake amount. A first control step of controlling so as to follow
A return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface,
Based on the linear characteristic of the return light amount of the near-field light detected by the return light amount detection step, control is performed such that the near-field light emission unit and the information recording surface maintain a predetermined distance in the near-field. 2. An information recording control method, comprising: When the return light amount detected in the return light amount detection step is larger than a predetermined threshold value, a third control is performed such that the near-field light emitting unit is disposed in a near field with respect to the information recording surface of the disk-shaped optical recording medium. 8. The information recording control method according to claim 7, further comprising the following control steps. A light beam emitted from the light source is condensed, and a surface shake amount detection for detecting a surface shake amount of the disk-shaped optical recording medium from return light of the light beam emitted to the information recording surface of the disk-shaped optical recording medium. Process and
In the storing step, at a timing when a pulse signal is generated in the pulse signal generating step, the amount of surface shake at a predetermined radius of the disk-shaped optical recording medium detected by the surface shake amount detection step is determined in the counting step. 8. The information recording control method according to claim 7, wherein the information is stored in the storage unit in association with the count value. The storage means stores an amount of runout at a radius Rm of the disc-shaped optical recording medium,
In the gain generation step, the gain at the radial position Rn detected in the radial position information detecting step is calculated by β × from the amplitude value β of the largest surface shake amount in the radius Rm stored in the storage means. (Rn / Rm)
The information recording control method according to claim 7, wherein the information recording control method is generated by the following. Mounting means for mounting a removable disk-shaped optical recording medium;
Rotation driving means for rotating the disc-shaped optical recording medium mounted on the mounting means at a predetermined number of rotations,
Pulse signal generating means for generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means;
Counting means for counting N pulse signals generated by the pulse signal generating means;
Storage means for storing the amount of surface deviation detected at the timing when the pulse signal is generated by the pulse signal generation means, in association with the count value by the counting means, and the radial position information;
A light source for emitting a light beam of a predetermined wavelength modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium,
A light beam emitted from the light source is condensed, and when placed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, the converged light beam is emitted to the information recording surface as near-field light. Near-field light emitting means,
Radial position information detecting means for detecting radial position information indicating the radial position of the information recording surface of the disc-shaped optical recording medium to which the near-field light emitting means is irradiating the light beam,
A surface-blur amount reading unit that reads a surface-blur amount stored in the storage unit according to the count value of the pulse signal counted by the counting unit and the radial position information detected by the radial position information detecting unit. When,
First control means for controlling the near-field light emitting means to follow the surface shake amount based on the surface shake amount read by the surface shake amount reading means;
Return light amount detection means for detecting the return light amount of the near-field light emitted to the information recording surface,
A second control unit that controls the near-field light emitting unit to maintain a predetermined distance within the near field with respect to the information recording surface, based on a linear characteristic of a returning light amount of the near-field light detected by the returning light amount detecting unit. An information recording apparatus, comprising: When the return light amount detected by the return light amount detection means is larger than a predetermined threshold value, the near-field light emitting means is controlled to be arranged in a near field with respect to the information recording surface of the disk-shaped optical recording medium. The information recording apparatus according to claim 11, further comprising a control unit. Optical means for condensing the light beam emitted from the light source and emitting the information beam to the information recording surface of the disc-shaped optical recording medium;
Surface deviation detection means for detecting the surface deviation of the disc-shaped optical recording medium from the return light of the light beam emitted by the optical means,
The storage means stores the amount of runout at the timing when the pulse signal is generated by the pulse signal generation means in association with the count value of the counting means and the radial position information of the disk-shaped optical recording medium. The information recording device according to claim 11, wherein: 12. The information recording apparatus according to claim 11, wherein the near-field light emitting means has an SIL (Solid Immersion Lens). 12. The information recording apparatus according to claim 11, wherein the near-field light emitting means has a SIM (Solid Immersion Mirror). A mounting process of mounting a removable disk-shaped optical recording medium,
A rotation driving step of rotating the mounted disk-shaped optical recording medium at a predetermined rotation speed,
A pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving step;
A counting step of counting N pulse signals generated in the pulse signal generating step;
A storage step of storing the amount of surface deviation detected at the timing when the pulse signal is generated in the pulse signal generation step in the storage means in association with the count value in the counting step and the radial position information;
A light beam of a predetermined wavelength emitted from a light source modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium is condensed and arranged in a near field with respect to the information recording surface of the disc-shaped optical recording medium. Near-field light emission means, near-field light emission step of emitting the collected light beam to the information recording surface as near-field light,
A radial position information detecting step of detecting radial position information indicating a radial position of an information recording surface of the disc-shaped optical recording medium on which the near-field light emitting unit irradiates the light beam;
A surface blur amount reading step of reading the surface blur amount stored in the storage step according to the count value of the pulse signal counted in the counting step and the radial position information detected in the radial position information detecting step When,
A first control step of controlling the near-field light emitting unit to follow the surface shake amount based on the surface shake amount read in the surface shake amount reading step;
A return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface,
A second control unit that controls the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the near-field light detected in the return light amount detection step. An information recording control method, comprising: When the return light amount detected in the return light amount detection step is larger than a predetermined threshold value, a third control is performed such that the near-field light emitting unit is disposed in a near field with respect to the information recording surface of the disk-shaped optical recording medium. 17. The information recording control method according to claim 16, comprising the following control steps. A light beam emitted from the light source is condensed, and a surface shake amount detection for detecting a surface shake amount of the disk-shaped optical recording medium from return light of the light beam emitted to the information recording surface of the disk-shaped optical recording medium. Process and
The storage step associates the amount of surface deviation at the timing when the pulse signal is generated in the pulse signal generation step with the count value in the counting step and the radial position information of the disk-shaped optical recording medium, and 17. The information recording control method according to claim 16, wherein the information recording control method is stored. Mounting means for mounting a removable disk-shaped optical recording medium;
A light source for emitting a light beam of a predetermined wavelength modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium,
Optical means for condensing the light beam emitted from the light source and emitting the information beam to the information recording surface of the disc-shaped optical recording medium;
Surface shake amount detection means for detecting the surface shake amount of the disc-shaped optical recording medium from the return light of the light beam emitted by the optical means,
A light beam emitted from the light source is condensed, and when placed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, the converged light beam is emitted to the information recording surface as near-field light. Near-field light emitting means,
Return light amount detection means for detecting the return light amount of the near-field light emitted to the information recording surface,
When the surface shake amount detected by the surface shake amount detection means is equal to or greater than a first threshold, a first control that controls the near-field light emitting means to follow the surface shake amount based on the surface shake amount. Control means;
When the surface shake amount detected by the surface shake amount detection means is smaller than the first threshold, the near-field light emission is performed based on the linear characteristic of the return light amount of the near-field light detected by the return light amount detection means. An information recording apparatus, comprising: a second control unit that controls the unit to maintain a predetermined distance in the near field with respect to the information recording surface. When the return light amount detected by the return light amount detection means is larger than a second threshold value, a third control is performed such that the near-field light emission means is disposed in a near field with respect to the information recording surface of the disk information recording medium. 20. The information recording apparatus according to claim 19, further comprising a control unit. 20. The information recording apparatus according to claim 19, wherein the near-field light emitting means has an SIL (Solid Immersion Lens). 20. The information recording apparatus according to claim 19, wherein said near-field light emitting means has a SIM (Solid Immersion Mirror). A mounting process of mounting a removable disk-shaped optical recording medium,
A light beam of a predetermined wavelength emitted from a light source modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium is condensed, and light emitted to the information recording surface of the disc-shaped optical recording medium is emitted. A surface shake amount detection step of detecting the surface shake amount of the disc-shaped optical recording medium from the return light of the beam,
A light beam emitted from the light source is condensed, and a near-field light emitting unit arranged in a near field with respect to an information recording surface of the disc-shaped optical recording medium uses the condensed light beam as a near-field light to generate the information. A near-field light emitting step of emitting to the recording surface,
A return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface,
A first control step of controlling the near-field light emitting means to follow the surface shake amount when the surface shake amount detected by the surface shake amount detection step is equal to or greater than a first threshold value;
When the surface shake amount detected by the surface shake amount detection step is smaller than the first threshold, the near-field light emission is performed based on the linear characteristic of the return light amount of the near-field light detected by the return light amount detection step. A second control step of controlling the means to maintain a predetermined distance in the near field with respect to the information recording surface. When the return light amount detected in the return light amount detection step is larger than a second threshold value, a third control is performed such that the near-field light emission step is arranged in a near field with respect to the information recording surface of the disk information recording medium. 24. The information recording control method according to claim 23, further comprising the following control steps. Mounting means for mounting a removable disk-shaped optical recording medium;
Rotation driving means for rotating the disc-shaped optical recording medium mounted on the mounting means at a predetermined number of rotations,
Pulse signal generating means for generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means;
Counting means for counting N pulse signals generated by the pulse signal generating means;
Storage means for storing the amount of runout of a predetermined radius detected at the timing when the pulse signal is generated by the pulse signal generation means, in association with the count value by the counting means,
A light source for emitting a light beam of a predetermined wavelength for reproducing predetermined information recorded on the disc-shaped optical recording medium,
A light beam emitted from the light source is condensed, and when placed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, the converged light beam is emitted to the information recording surface as near-field light. Near-field light emitting means,
Radial position information detecting means for detecting radial position information indicating the radial position of the information recording surface of the disc-shaped optical recording medium to which the near-field light emitting means is irradiating the light beam,
Gain generating means for generating a predetermined gain corresponding to the radial position information detected by the radial position information detecting means,
In accordance with the count value of the pulse signal counted by the counting means, a surface blur amount reading means for reading the surface blur amount stored in the storage means,
A control signal is generated by multiplying the surface shake amount read by the surface shake amount reading unit by the predetermined gain generated by the gain generating unit, and the near-field light emitting unit is controlled by the surface shake amount. First control means for performing control so as to follow, and return light quantity detection means for detecting the return light quantity of the near-field light emitted to the information recording surface;
A second control unit that controls the near-field light emitting unit to maintain a predetermined distance within the near field with respect to the information recording surface, based on a linear characteristic of a returning light amount of the near-field light detected by the returning light amount detecting unit. An information reproducing apparatus, comprising: A signal extraction unit that extracts a reproduction signal and a gap error signal by separating the return light amount detected by the return light amount detection unit at a predetermined frequency;
The second control means controls the near-field light emitting means to maintain a predetermined distance in the near field with respect to the information recording surface, based on a linear characteristic of the gap error signal extracted by the signal extraction means. 26. The information reproducing apparatus according to claim 25, wherein the information reproducing apparatus performs control. Polarization separation means for separating return light of the near-field light emitted to the information recording surface into a first return light and a second return light according to a difference in polarization plane;
Reproducing signal detecting means for detecting the first return light separated by the polarization separating means as a reproducing signal;
The return light amount detecting means detects a return light amount of the second return light separated by the polarization separation means,
The second control means controls the near-field light emitting means in the near field with respect to the information recording surface based on a linear characteristic of the return light amount of the second return light detected by the return light detection means. 26. The information reproducing apparatus according to claim 25, wherein the information reproducing apparatus is controlled so as to keep the distance. When the return light amount detected by the return light amount detection means is larger than a predetermined threshold value, the near-field light emitting means is controlled to be arranged in a near field with respect to the information recording surface of the disk-shaped optical recording medium. 26. The information reproducing apparatus according to claim 25, further comprising: control means. Optical means for condensing the light beam emitted from the light source and emitting the information beam to the information recording surface of the disc-shaped optical recording medium;
Surface deviation detection means for detecting the surface deviation of the disc-shaped optical recording medium from the return light of the light beam emitted by the optical means,
The storage means stores, at the timing at which a pulse signal is generated by the pulse signal generation means, the amount of surface shake at a predetermined radius of the disk-shaped optical recording medium detected by the surface shake amount detection means, by the counting means. 26. The information reproducing apparatus according to claim 25, wherein the information is stored in association with a count value. Assuming that the storage means stores the amount of runout at a radius Rm of the disc-shaped optical recording medium,
The gain generating means calculates, from β, an amplitude value in the case of the largest surface shake amount in the radius Rm stored in the storage means from β, the amplitude value at the radial position Rn detected by the radial position information detecting means. Gain is β × (Rn / Rm)
The information reproducing apparatus according to claim 25, wherein the information reproducing apparatus generates the information. 26. The information reproducing apparatus according to claim 25, wherein the near-field light emitting means has an SIL (Solid Immersion Lens). 26. The information reproducing apparatus according to claim 25, wherein the near-field light emitting means has a SIM (Solid Immersion Mirror). A mounting process of mounting a removable disk-shaped optical recording medium,
A rotation driving step of rotating the mounted disk-shaped optical recording medium at a predetermined rotation speed,
A pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving step;
A counting step of counting N pulse signals generated in the pulse signal generating step;
A storage step of storing a surface shake amount of a predetermined radius detected at a timing when a pulse signal is generated in the pulse signal generation step in a storage unit in association with the count value in the counting step;
A light beam of a predetermined wavelength emitted from a light source for reproducing predetermined information recorded on the disk-shaped optical recording medium is condensed, and a near-field light is arranged in a near field with respect to an information recording surface of the disk-shaped optical recording medium. A near-field light emitting step of emitting the focused light beam to the information recording surface as near-field light,
A radial position information detecting step of detecting radial position information indicating a radial position of an information recording surface of the disc-shaped optical recording medium on which the near-field light emitting unit irradiates the light beam;
A gain generating step of generating a predetermined gain corresponding to the radial position information detected by the radial position information detecting step,
A surface-blur amount reading step of reading a surface-blur amount stored in the storage means according to the count value of the pulse signal counted in the counting step;
A control signal is generated by multiplying the surface shake amount read in the surface shake amount reading step by the predetermined gain generated in the gain generation step, and the near-field light emission step is performed by the surface shake amount. A first control step of controlling to follow, and a return light amount detecting step of detecting a return light amount of the near-field light emitted to the information recording surface;
A second control unit that controls the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the near-field light detected in the return light amount detection step. An information reproduction control method, comprising: a control step. A signal extraction step of extracting a reproduction signal and a gap error signal by separating the return light amount detected by the return light amount detection step at a predetermined frequency,
The second control step controls the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on a linear characteristic of the gap error signal extracted in the signal extraction step. The information reproduction control method according to claim 33, wherein the method is controlled. A polarization separation step of separating return light of near-field light emitted to the information recording surface into a first return light and a second return light according to a difference in polarization plane;
A reproduction signal detection step of detecting the first return light separated in the polarization separation step as a reproduction signal,
The return light amount detection step detects a return light amount of the second return light separated in the polarization separation step,
In the second control step, the near-field light emitting unit is controlled in a predetermined manner in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the second return light detected in the return light amount detection step. 34. The information reproduction control method according to claim 33, wherein the control is performed such that the distance is maintained. When the return light amount detected in the return light amount detection step is larger than a predetermined threshold value, a third control is performed such that the near-field light emitting unit is disposed in a near field with respect to the information recording surface of the disk-shaped optical recording medium. 34. The information reproduction control method according to claim 33, further comprising the control step of: A surface shake amount detecting step of condensing a light beam emitted from the light source and detecting a surface shake amount of the disk-shaped optical recording medium from return light of the light beam emitted to the information recording surface of the disk-shaped optical recording medium With
In the storing step, at a timing when a pulse signal is generated in the pulse signal generating step, the amount of surface shake at a predetermined radius of the disk-shaped optical recording medium detected by the surface shake amount detection step is determined in the counting step. The information reproduction control method according to claim 33, wherein the information is stored in the storage unit in association with the count value. The storage means stores an amount of runout at a radius Rm of the disc-shaped optical recording medium,
In the gain generation step, the amplitude value in the case of the largest surface shake amount in the radius Rm stored in the storage means is obtained from β by using the amplitude value at the radial position Rn detected in the radial position information detection step. Gain is β × (Rn / Rm)
The information reproduction control method according to claim 33, wherein the information reproduction control method generates the information. Mounting means for mounting a removable disk-shaped optical recording medium;
Rotation driving means for rotating the disc-shaped optical recording medium mounted on the mounting means at a predetermined number of rotations,
Pulse signal generating means for generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means;
Counting means for counting N pulse signals generated by the pulse signal generating means;
Storage means for storing the amount of surface deviation detected at the timing when the pulse signal is generated by the pulse signal generation means, in association with the count value by the counting means, and the radial position information;
A light source for emitting a light beam of a predetermined wavelength for reproducing predetermined information recorded on the disc-shaped optical recording medium,
A light beam emitted from the light source is condensed, and when placed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, the converged light beam is emitted to the information recording surface as near-field light. Near-field light emitting means,
Radial position information detecting means for detecting radial position information indicating the radial position of the information recording surface of the disc-shaped optical recording medium to which the near-field light emitting means is irradiating the light beam,
A surface-blur amount reading unit that reads a surface-blur amount stored in the storage unit according to the count value of the pulse signal counted by the counting unit and the radial position information detected by the radial position information detecting unit. When,
First control means for controlling the near-field light emitting means to follow the surface shake amount based on the surface shake amount read by the surface shake amount reading means; Return light amount detecting means for detecting the return light amount of the near-field light,
A second control unit that controls the near-field light emitting unit to maintain a predetermined distance within the near field with respect to the information recording surface, based on a linear characteristic of a returning light amount of the near-field light detected by the returning light amount detecting unit. An information reproducing apparatus, comprising: A signal extraction unit that extracts a reproduction signal and a gap error signal by separating the return light amount detected by the return light amount detection unit at a predetermined frequency;
The second control means controls the near-field light emitting means to maintain a predetermined distance in the near field with respect to the information recording surface, based on a linear characteristic of the gap error signal extracted by the signal extraction means. The information reproducing apparatus according to claim 39, wherein the information reproducing apparatus performs control. Polarization separation means for separating return light of the near-field light emitted to the information recording surface into a first return light and a second return light according to a difference in polarization plane;
Reproducing signal detecting means for detecting the first return light separated by the polarization separating means as a reproducing signal;
The return light amount detecting means detects a return light amount of the second return light separated by the polarization separation means,
The second control means controls the near-field light emitting means within the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the second return light detected by the return light detection means. 40. The information reproducing apparatus according to claim 39, wherein the information reproducing apparatus is controlled so as to keep the distance. When the return light amount detected by the return light amount detection means is larger than a predetermined threshold value, the near-field light emitting means is controlled to be arranged in a near field with respect to the information recording surface of the disk-shaped optical recording medium. 40. The information reproducing apparatus according to claim 39, further comprising: control means. Optical means for condensing the light beam emitted from the light source and emitting the information beam to the information recording surface of the disc-shaped optical recording medium;
Surface deviation detection means for detecting the surface deviation of the disc-shaped optical recording medium from the return light of the light beam emitted by the optical means,
The storage means stores the amount of runout at the timing when the pulse signal is generated by the pulse signal generation means in association with the count value of the counting means and the radial position information of the disk-shaped optical recording medium. 40. The information reproducing apparatus according to claim 39, wherein: 40. The information reproducing apparatus according to claim 39, wherein the near-field light emitting means has an SIL (Solid Immersion Lens). 40. The information reproducing apparatus according to claim 39, wherein the near-field light emitting means has a SIM (Solid Immersion Mirror). A mounting process of mounting a removable disk-shaped optical recording medium,
A rotation driving step of rotating the mounted disk-shaped optical recording medium at a predetermined rotation speed,
A pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving step;
A counting step of counting N pulse signals generated in the pulse signal generating step;
A storage step of storing the amount of surface deviation detected at the timing when the pulse signal is generated in the pulse signal generation step in the storage means in association with the count value in the counting step and the radial position information;
A light beam of a predetermined wavelength emitted from a light source for reproducing predetermined information recorded on the disk-shaped optical recording medium is condensed, and a near-field light is arranged in a near field with respect to an information recording surface of the disk-shaped optical recording medium. A near-field light emitting step of emitting the focused light beam to the information recording surface as near-field light,
Radial position information detecting step of detecting the radial position information indicating the radial position of the information recording surface of the disk-shaped optical recording medium is irradiating the light beam, the near-field light emitting step,
A surface blur amount reading step of reading the surface blur amount stored in the storage step according to the count value of the pulse signal counted in the counting step and the radial position information detected in the radial position information detecting step When,
A first control step of controlling the near-field light emission step to follow the surface shake amount based on the surface shake amount read in the surface shake amount reading step;
A return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface,
A second step of controlling the near-field light emitting step to maintain a predetermined distance within the near field with respect to the information recording surface, based on a linear characteristic of the returning light amount of the near-field light detected by the returning light quantity detecting step. An information reproduction control method, comprising: A signal extraction step of extracting a reproduction signal and a gap error signal by separating the return light amount detected by the return light amount detection step at a predetermined frequency,
The second control step controls the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on a linear characteristic of the gap error signal extracted in the signal extraction step. 47. The information reproduction control method according to claim 46, wherein the method is controlled. A polarization separation step of separating return light of near-field light emitted to the information recording surface into a first return light and a second return light according to a difference in polarization plane;
A reproduction signal detection step of detecting the first return light separated in the polarization separation step as a reproduction signal,
The return light amount detection step detects a return light amount of the second return light separated in the polarization separation step,
The second control step includes controlling the near-field light emitting means in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the second return light detected in the return light amount detection step. 47. The information reproduction control method according to claim 46, wherein the control is performed such that the distance is maintained. When the return light amount detected in the return light amount detection step is larger than a predetermined threshold value, a third control is performed such that the near-field light emitting unit is disposed in a near field with respect to the information recording surface of the disk-shaped optical recording medium. 47. The information reproduction control method according to claim 46, further comprising the following control steps. A light beam emitted from the light source is condensed, and a surface shake amount detection for detecting a surface shake amount of the disk-shaped optical recording medium from return light of the light beam emitted to the information recording surface of the disk-shaped optical recording medium. Process and
The storage step associates the amount of surface deviation at the timing when the pulse signal is generated in the pulse signal generation step with the count value in the counting step and the radial position information of the disk-shaped optical recording medium, and 47. The information reproduction control method according to claim 46, wherein the information is stored. Mounting means for mounting a removable disk-shaped optical recording medium;
A light source for emitting a light beam of a predetermined wavelength for reproducing predetermined information recorded on the information recording surface of the disc-shaped optical recording medium,
Optical means for condensing the light beam emitted from the light source and emitting the information beam to the information recording surface of the disc-shaped optical recording medium;
Surface shake amount detection means for detecting the surface shake amount of the disc-shaped optical recording medium from the return light of the light beam emitted by the optical means,
A light beam emitted from the light source is condensed, and when placed in a near field with respect to the information recording surface of the disc-shaped optical recording medium, the converged light beam is emitted to the information recording surface as near-field light. Near-field light emitting means,
Return light amount detection means for detecting the return light amount of the near-field light emitted to the information recording surface,
A first control unit that controls the driving unit based on the surface shake amount when the surface shake amount detected by the surface shake amount detection unit is equal to or greater than a first threshold;
When the surface shake amount detected by the surface shake amount detection means is smaller than the first threshold, the near-field light emission is performed based on the linear characteristic of the return light amount of the near-field light detected by the return light amount detection means. An information reproducing apparatus comprising: a second control unit that controls a unit to maintain a predetermined distance in the near field with respect to the information recording surface. A signal extraction unit that extracts a reproduction signal and a gap error signal by separating the return light amount detected by the return light amount detection unit at a predetermined frequency;
The second control means controls the near-field light emitting means to maintain a predetermined distance in the near field with respect to the information recording surface, based on a linear characteristic of the gap error signal extracted by the signal extraction means. The information reproducing apparatus according to claim 51, wherein the information reproducing apparatus controls. Polarization separation means for separating return light of the near-field light emitted to the information recording surface into a first return light and a second return light according to a difference in polarization plane;
Reproducing signal detecting means for detecting the first return light separated by the polarization separating means as a reproducing signal;
The return light amount detecting means detects a return light amount of the second return light separated by the polarization separation means,
The second control means controls the near-field light emitting means within the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the second return light detected by the return light detection means. 52. The information reproducing apparatus according to claim 51, wherein control is performed so as to keep the distance of the information reproducing apparatus. When the return light amount detected by the return light amount detection means is larger than a second threshold value, a third control is performed such that the near-field light emitting means is disposed in a near field with respect to the information recording surface of the disk information recording medium. 52. The information reproducing apparatus according to claim 51, further comprising a control unit. 52. The information reproducing apparatus according to claim 51, wherein the near-field light emitting means has an SIL (Solid Immersion Lens). 52. The information reproducing apparatus according to claim 51, wherein the near-field light emitting means has a SIM (Solid Immersion Mirror). A mounting process of mounting a removable disk-shaped optical recording medium,
A light beam of a predetermined wavelength emitted from a light source for reproducing predetermined information recorded on an information recording surface of the disc-shaped optical recording medium is condensed, and emitted to an information recording surface of the disc-shaped optical recording medium. A surface shake amount detection step of detecting the surface shake amount of the disk-shaped optical recording medium from the return light of the light beam,
A light beam emitted from the light source is condensed, and a near-field light emitting unit arranged in a near field with respect to an information recording surface of the disc-shaped optical recording medium uses the condensed light beam as a near-field light to generate the information. A near-field light emitting step of emitting to the recording surface,
A return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface,
A first control step of controlling the near-field light emitting means to follow the surface shake amount when the surface shake amount detected by the surface shake amount detection step is equal to or greater than a first threshold value;
When the surface shake amount detected by the surface shake amount detection step is smaller than the first threshold, the near-field light emission is performed based on the linear characteristic of the return light amount of the near-field light detected by the return light amount detection step. A second control step of controlling the means to maintain a predetermined distance in the near field with respect to the information recording surface. A signal extraction step of extracting a reproduction signal and a gap error signal by separating the return light amount detected by the return light amount detection step at a predetermined frequency,
The second control step controls the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on a linear characteristic of the gap error signal extracted in the signal extraction step. 58. The information reproduction control method according to claim 57, wherein control is performed. A polarization separation step of separating return light of near-field light emitted to the information recording surface into a first return light and a second return light according to a difference in polarization plane;
A reproduction signal detection step of detecting the first return light separated in the polarization separation step as a reproduction signal,
The return light amount detection step detects a return light amount of the second return light separated in the polarization separation step,
The second control step includes controlling the near-field light emitting means in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the second return light detected in the return light amount detection step. 58. The information reproduction control method according to claim 57, wherein the control is performed such that the distance is maintained. When the return light amount detected in the return light amount detection step is larger than a second threshold value, a third control is performed such that the near-field light emitting unit is disposed in a near field with respect to the information recording surface of the disk-shaped recording medium. 58. The information reproduction control method according to claim 57, further comprising the control step of: Mounting means for mounting a removable disk-shaped optical recording medium;
Rotation driving means for rotating the disk-shaped optical recording medium mounted on the mounting means,
Pulse signal generating means for generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means;
Voltage value conversion means for converting the frequency of the pulse signal generated by the pulse signal generation means into a voltage value,
Voltage value conversion means for comparing the voltage value converted by the voltage value conversion means with a predetermined reference voltage value,
First rotation speed control means for controlling the rotation speed of the rotation drive means based on a comparison result by the voltage value comparison means;
Phase comparing means for comparing the phase of the pulse signal generated by the pulse signal generating means with the phase of a predetermined reference signal,
Second rotation speed control means for controlling the rotation speed of the rotation drive means based on the comparison result by the phase comparison means;
A light source for emitting a light beam of a predetermined wavelength modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium,
When the light beam emitted from the light source is condensed and arranged in the near field with respect to the information recording surface of the disc-shaped optical recording medium, the converged light beam is emitted as the near-field light to the information recording surface. Near-field light emitting means,
Return light amount detection means for detecting the return light amount of the near-field light emitted to the information recording surface,
The near-field light emitting means is controlled to maintain a predetermined distance (gap) in the near field with respect to the information recording surface, based on a linear characteristic of a returning light quantity of the near-field light detected by the returning light quantity detecting means. First gap control means for
The rotation drive unit is controlled by the first rotation speed control unit so that the disk-shaped optical recording medium rotates at a predetermined rotation speed. Control means for starting the control by the rotation speed control means and starting the control by the first gap control means in response to the result of the phase comparison by the phase comparison means being equal to or less than a predetermined threshold value. Characteristic information recording device. If the return light amount detected by the return light amount detection means is larger than a predetermined threshold, the near-field light emitting means is controlled to be arranged in a near field with respect to the information recording surface of the disk-shaped optical recording medium. 62. The information recording apparatus according to claim 61, further comprising: a gap control unit. 62. The information recording apparatus according to claim 61, wherein the near-field light emitting means has an SIL (Solid Immersion Lens). 62. The information recording apparatus according to claim 61, wherein the near-field light emitting means has a SIM (Solid Immersion Mirror). A mounting process of mounting a removable disk-shaped optical recording medium,
A rotation drive step of rotating the mounted disk-shaped optical recording medium by rotation drive means,
A pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined period while the disk-shaped optical recording medium makes one rotation by the rotation driving means;
A voltage value conversion step of converting the frequency of the pulse signal generated in the pulse signal generation step into a voltage value,
A voltage value conversion step of comparing the voltage value converted in the voltage value conversion step with a predetermined reference voltage value,
A first rotation speed control step of controlling the rotation speed of the rotation drive unit based on a result of the comparison in the voltage value comparison step;
A phase comparison step of comparing the phase of the pulse signal generated in the pulse signal generation step with the phase of a predetermined reference signal,
A second rotation speed control step of controlling the rotation speed of the rotation drive unit based on a comparison result obtained by the phase comparison step;
A light beam having a predetermined wavelength, which is modulated by recording information to be recorded on the information recording surface of the disc-shaped optical recording medium and emitted from the light source, is condensed and arranged in a near field with respect to the information recording surface of the disc-shaped optical recording medium. Near-field light emission means, the near-field light emission step of emitting the focused light beam to the information recording surface as the near-field light,
A return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface,
The near-field light emitting unit is controlled to maintain a predetermined distance (gap) in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the near-field light detected in the return light amount detection step. A first gap control step of
The rotation drive means is controlled by the first rotation speed control step so that the disk-shaped optical recording medium rotates at a predetermined rotation speed. A control step of starting the control by the rotation speed control step, and starting the control by the first gap control step when the phase comparison result by the phase comparison step is equal to or less than a predetermined threshold value. Characteristic information recording control method. When the return light amount detected in the return light amount detection step is larger than a predetermined threshold, the near-field light emitting unit is controlled to be arranged in a near field with respect to the information recording surface of the disk-shaped optical recording medium. The information recording control method according to claim 65, further comprising the step of: Mounting means for mounting a removable disk-shaped optical recording medium;
Rotation driving means for rotating the disk-shaped optical recording medium mounted on the mounting means,
Pulse signal generating means for generating N (N is a natural number) pulse signals at a predetermined cycle while the disk-shaped optical recording medium makes one rotation by the rotation driving means;
Voltage value conversion means for converting the frequency of the pulse signal generated by the pulse signal generation means into a voltage value,
Voltage value conversion means for comparing the voltage value converted by the voltage value conversion means with a predetermined reference voltage value,
First rotation speed control means for controlling the rotation speed of the rotation drive means based on a comparison result by the voltage value comparison means;
Phase comparing means for comparing the phase of the pulse signal generated by the pulse signal generating means with the phase of a predetermined reference signal,
Second rotation speed control means for controlling the rotation speed of the rotation drive means based on the comparison result by the phase comparison means;
A light source for emitting a light beam of a predetermined wavelength for reproducing predetermined information recorded on the disk-shaped recording medium,
When the light beam emitted from the light source is condensed and arranged in the near field with respect to the information recording surface of the disc-shaped optical recording medium, the converged light beam is emitted as the near-field light to the information recording surface. Near-field light emitting means,
Return light amount detection means for detecting the return light amount of the near-field light emitted to the information recording surface,
The near-field light emitting means is controlled to maintain a predetermined distance (gap) in the near field with respect to the information recording surface, based on a linear characteristic of a returning light quantity of the near-field light detected by the returning light quantity detecting means. First gap control means for
The rotation drive unit is controlled by the first rotation speed control unit so that the disk-shaped optical recording medium rotates at a predetermined rotation speed. Control means for starting the control by the rotation speed control means and starting the control by the first gap control means in response to the result of the phase comparison by the phase comparison means being equal to or less than a predetermined threshold value. Characteristic information reproducing device. A signal extraction unit that extracts a reproduction signal and a gap error signal by separating the return light amount detected by the return light amount detection unit at a predetermined frequency;
The first gap control unit controls the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on a linear characteristic of the gap error signal extracted by the signal extraction unit. 67. The information reproducing apparatus according to claim 67, wherein the information reproducing apparatus is controlled. Polarization separation means for separating return light of the near-field light emitted to the information recording surface into a first return light and a second return light according to a difference in polarization plane;
Reproducing signal detecting means for detecting the first return light separated by the polarization separating means as a reproducing signal;
The return light amount detecting means detects a return light amount of the second return light separated by the polarization separation means,
The first gap control unit controls the near-field light emitting unit in the near field with respect to the information recording surface based on a linear characteristic of the return light amount of the second return light detected by the return light amount detection unit. The information reproducing apparatus according to claim 67, wherein control is performed so as to maintain a predetermined distance. If the return light amount detected by the return light amount detection means is larger than a predetermined threshold, the near-field light emitting means is controlled to be arranged in a near field with respect to the information recording surface of the disk-shaped optical recording medium. The information reproducing apparatus according to claim 67, further comprising: a gap control unit. 68. The information reproducing apparatus according to claim 67, wherein the near-field light emitting means has an SIL (Solid Immersion Lens). 68. The information reproducing apparatus according to claim 67, wherein the near-field light emitting means has a SIM (Solid Immersion Mirror). A mounting process of mounting a removable disk-shaped optical recording medium,
A rotation driving step of rotating the mounted removable disk-shaped optical recording medium by rotation driving means,
A pulse signal generating step of generating N (N is a natural number) pulse signals at a predetermined period while the disk-shaped optical recording medium makes one rotation by the rotation driving means;
A voltage value conversion step of converting the frequency of the pulse signal generated in the pulse signal generation step into a voltage value,
A voltage value conversion step of comparing the voltage value converted in the voltage value conversion step with a predetermined reference voltage value,
A first rotation speed control step of controlling the rotation speed of the rotation drive unit based on a result of the comparison in the voltage value comparison step;
A phase comparison step of comparing the phase of the pulse signal generated in the pulse signal generation step with the phase of a predetermined reference signal,
A second rotation speed control step of controlling the rotation speed of the rotation drive unit based on a comparison result obtained by the phase comparison step;
A light beam of a predetermined wavelength emitted from a light source for reproducing predetermined information recorded on the disc-shaped recording medium is condensed, and a near-field arranged in a near field with respect to an information recording surface of the disc-shaped optical recording medium A light emitting means, a near-field light emitting step of emitting the collected light beam to the information recording surface as near-field light,
A return light amount detection step of detecting a return light amount of the near-field light emitted to the information recording surface,
The near-field light emitting unit is controlled to maintain a predetermined distance (gap) in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the near-field light detected in the return light amount detection step. A first gap control step of
The rotation drive means is controlled by the first rotation speed control step so that the disk-shaped optical recording medium rotates at a predetermined rotation speed. A control step of starting the control by the rotation speed control step, and starting the control by the first gap control step when the phase comparison result by the phase comparison step is equal to or less than a predetermined threshold value. Characteristic information reproduction control method. A signal extraction step of extracting a reproduction signal and a gap error signal by separating the return light amount detected by the return light amount detection step at a predetermined frequency,
The first gap control step controls the near-field light emitting unit to maintain a predetermined distance in the near field with respect to the information recording surface based on a linear characteristic of the gap error signal extracted in the signal extraction step. 74. The information reproduction control method according to claim 73, wherein the control is performed in the following manner. A polarization separation step of separating return light of near-field light emitted to the information recording surface into a first return light and a second return light according to a difference in polarization plane;
A reproduction signal detection step of detecting the first return light separated in the polarization separation step as a reproduction signal,
The return light amount detection step detects a return light amount of the second return light separated in the polarization separation step,
The first gap control step includes controlling the near-field light emitting unit in the near field with respect to the information recording surface based on a linear characteristic of a return light amount of the second return light detected in the return light amount detection step. The information reproduction control method according to claim 73, wherein control is performed so as to maintain a predetermined distance. If the return light amount detected in the return light amount detection step is larger than a predetermined threshold, the near-field light emitting means is controlled to be arranged in a near field with respect to the information recording surface of the disk-shaped optical recording medium. The information reproduction control method according to claim 73, further comprising the step of:

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