JP4264524B2 - Signal recording apparatus and method, and signal reproducing apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal recording apparatus and method for recording a signal on an optical recording medium, and a signal reproducing apparatus and method for reproducing a signal from the optical recording medium.
[0002]
[Prior art]
As a means for recording and / or reproducing, there is one that uses near-field light by a solid immersion lens such as a SIL (Solid Immersion Lens) composed of a two-group lens or a single lens SIM (Solid Immersion Mirror). By using such near-field light, it is possible to further reduce the spot diameter in response to the need for higher density optical disks. The SIL is interposed between the condensing lens and the optical disk as an optical recording medium, and is a high refractive index lens having a shape obtained by cutting off a part of a spherical lens. The opposite surface is arranged facing the signal recording surface of the optical disc. By interposing such SIL between the condensing lens and the optical disk, it is possible to realize a numerical aperture larger than the numerical aperture of the condensing lens, thereby further reducing the spot diameter as described above. It becomes possible.
[0003]
In order to perform recording and reproduction on an optical disk using SIL, the recording laser is focused on the SIL end surface, and the distance between the SIL end surface (the surface facing the optical disk in the SIL) and the optical disk is a distance (light of light) that is generated. It is necessary to approach to a wavelength of 1/2 or less (typically about 200 nm or less) and to make the distance constant, and to make the focused spot on the optical disk constant.
[0004]
[Problems to be solved by the invention]
By the way, as the focus control for controlling the distance between the SIL end face and the optical disk to be constant, the first optical means for condensing the light to be irradiated onto the optical recording medium and the numerical aperture larger than the first optical means. Second optical means interposed between the first optical means and the optical disk to realize the numerical aperture, and total reflection from the optical disk in the near field region between the end surface of the second optical means and the optical disk There is means for holding the distance between the second optical means and the optical disk at a predetermined position by using the linear characteristic of the return light quantity (specifically, the return light quantity from the irradiation surface facing the optical disk). Such a technique is described in detail, for example, in a previous application (Japanese Patent Application No. 11-253296) filed by the applicant of the present application.
[0005]
In such focus control, control is performed by using the linear characteristic of the total reflected return light amount. Therefore, if the intensity of the light to be irradiated onto the optical disk (irradiation light intensity or laser power) is changed, the far field is changed accordingly. The total reflected return light amount in the field region varies, and the focus control target value is substantially deviated. When the focus control target value is deviated, the focus control is drawn at a position deviated from the original focus position, and the distance between the SIL end surface and the optical recording medium is changed according to the change of the irradiation light intensity. Will change. This is equivalent to evanescent coupling in the near-field region, but the coupling power at that time changes, which makes it impossible to record and reproduce signals stably.
[0006]
For this reason, every time the intensity of irradiation light on the optical disk is changed, the focus control target value is manually changed or the total reflected return light amount is normalized (standardized) with respect to the control target value. The distance between the SIL end surface and the signal recording surface of the optical disk is not changed.
[0007]
By the way, such a technique has the following problems.
[0008]
First, every time the intensity of light to be applied to the optical disk is changed, the control target value of focus control is manually changed or the total reflected return light amount is normalized with respect to the control target value (hereinafter referred to as adjustment collectively). In this case, it was necessary to stop the focus control operation once. Therefore, it has been impossible to continuously record and reproduce information by changing the light intensity during recording and reproduction with respect to the optical disc.
[0009]
Second, since the focus is stopped and manual adjustment is performed when the above-described adjustment is performed, an error before and after the adjustment occurs, and the reliability of recording and reproduction may be impaired. That is, there is a risk that the quality of a recorded or reproduced signal is deteriorated.
[0010]
Therefore, the present invention has been made in view of the above circumstances, and in the case of recording or reproducing a signal using near-field light, the lens end face does not depend on the change of irradiation light intensity (laser power). It is an object of the present invention to provide a signal recording apparatus and method, and a signal reproducing apparatus and method that make it possible to maintain a constant distance between the (optical means) and the recording medium.
[0011]
[Means for Solving the Problems]
  In order to solve the above-described problem, a signal recording apparatus according to the present invention is a signal recording apparatus that records a signal on an optical recording medium using near-field light. An optical means that is positioned close to the signal recording surface and collects near-field light by laser light on the optical recording medium, and a laser that automatically controls the laser intensity of the laser light from the light source when recording a signal on the optical recording medium Automatic intensity control means, light quantity correction means for correcting the light quantity of the return light from the optical means according to the intensity of the laser light emitted from the light source to record a signal on the optical recording medium, and the light quantity of the return light And a focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium, and the light quantity correction means adjusts the offset of the light quantity of the return light from the optical means. signal A positive signal, a second signal calibration unit that adjusts an offset of the amount of laser light from a light source whose laser intensity is automatically controlled by laser intensity automatic control means, a reference voltage setting unit that sets a predetermined voltage value, The offset is adjusted by the first signal calibrating unit and the arithmetic unit that divides the predetermined voltage value set by the reference voltage setting unit by the voltage value of the light amount of the laser light whose offset is adjusted by the second signal calibrating unit. A multiplication unit that obtains a constant value by multiplying the voltage value of the light quantity of the returned light by the division value obtained by the calculation unit, and the focus control means is based on the constant value obtained by the multiplication unit. The distance between the optical means and the signal recording surface of the optical recording medium is controlled to be constant.
[0012]
  The signal recording apparatus having such a configuration adjusts the offset of the light quantity of the return light from the optical means by the light quantity correction means, and adjusts the offset of the light quantity of the laser light from the light source whose laser intensity is automatically controlled. Set a predetermined voltage value, divide the set predetermined voltage value by the voltage value of the light amount of the laser beam with the offset adjusted, and divide the voltage value and the divided value of the light amount of the return light with the offset adjusted Multiplication is performed to obtain a constant value, and focus control is performed to control the distance between the optical means and the signal recording surface of the optical recording medium to be constant based on the obtained constant value.
[0013]
  In addition, a signal recording method according to the present invention is a signal recording method for recording a signal on an optical recording medium using near-field light in order to solve the above-described problem, and for recording a signal on the optical recording medium. Depending on the intensity of the laser light emitted from the light source, the optical recording medium is positioned close to the signal recording surface and returned from the optical means for condensing the near-field light by the laser light emitted from the light source onto the optical recording medium. A method for performing focus control to correct the light and control the distance between the optical means and the signal recording surface of the optical recording medium according to the light quantity of the return light, and offsetting the light quantity of the return light from the optical means , Adjust the offset of the laser light amount from the light source whose laser intensity is automatically controlled, set a predetermined voltage value, and set the predetermined voltage value of the light amount of the laser light whose offset is adjusted Divide by voltage value Then, a constant value is obtained by multiplying the voltage value of the light quantity of the return light with the offset adjusted and the division value, and based on the obtained constant value, between the optical means and the signal recording surface of the optical recording medium. Focus control is performed to keep the distance constant.
[0014]
  According to another aspect of the present invention, there is provided a signal reproducing apparatus for reproducing a signal from an optical recording medium using near-field light in order to solve the above problems. An optical unit that is positioned close to the signal recording surface of the medium and collects near-field light by laser light on the optical recording medium, and automatically controls the laser intensity of the laser light from the light source when recording a signal on the optical recording medium A laser intensity automatic control means, a light quantity correction means for correcting the light quantity of the return light from the optical means according to the intensity of the laser light emitted from the light source for reproducing a signal from the optical recording medium, and the return A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium according to the light quantity of light is provided, and the light quantity correction means adjusts the offset of the light quantity of the return light from the optical means. A first signal calibrating unit, a second signal calibrating unit for adjusting an offset of the amount of laser light from a light source whose laser intensity is automatically controlled by laser intensity automatic control means, and a reference for setting a predetermined voltage value A voltage setting unit; a calculation unit that divides the predetermined voltage value set by the reference voltage setting unit by the voltage value of the amount of laser light whose offset is adjusted by the second signal calibration unit; and a first signal calibration unit And a multiplication unit that obtains a constant value by multiplying the voltage value of the amount of the return light whose offset is adjusted by the division value obtained by the calculation unit, and the focus control means has a constant value obtained by the multiplication unit. Based on the value, the distance between the optical means and the signal recording surface of the optical recording medium is controlled to be constant.
[0015]
  The signal reproducing apparatus having such a configuration adjusts the offset of the light quantity of the return light from the optical means by the light quantity correction means, and records the laser intensity of the laser light from the light source when recording the signal on the optical recording medium. Adjusts the offset of the laser light quantity from the automatically controlled light source, sets a predetermined voltage value, divides the predetermined voltage value by the voltage value of the laser light quantity with the offset adjusted, and the offset is adjusted The constant value is obtained by multiplying the voltage value of the light quantity of the returned light and the division value, and the focus control means determines the distance between the optical means and the signal recording surface of the optical recording medium based on the obtained constant value. The distance is controlled to be constant.
[0016]
  In addition, a signal reproduction method according to the present invention is a signal reproduction method for reproducing a signal from an optical recording medium using near-field light in order to solve the above-described problem. Depending on the intensity of the laser light emitted from the light source, the return light from the optical means that is positioned close to the signal recording surface of the optical recording medium and focuses the near-field light by the laser light on the optical recording medium is corrected and returned. A signal reproduction method that performs focus control to control the distance between the optical means and the signal recording surface of the optical recording medium in accordance with the amount of light, and adjusts the offset of the amount of return light from the optical means, When recording a signal on the optical recording medium, adjust the offset of the laser light amount from the light source whose laser intensity from the light source is automatically controlled, set a predetermined voltage value, and set the predetermined voltage value. offset Divide by the voltage value of the adjusted laser light amount, multiply the voltage value of the return light amount by which the offset is adjusted and the division value to obtain a constant value, and based on the acquired constant value, optical means And focus control for controlling the distance between the optical recording medium and the signal recording surface of the optical recording medium to be constant.
[0017]
  In order to solve the above-described problem, a signal recording apparatus according to the present invention is a signal recording apparatus that records a signal on an optical recording medium using near-field light, a light source that emits laser light, and optical recording. An optical unit that is positioned close to the signal recording surface of the medium and collects near-field light by laser light on the optical recording medium, and the amount of the return light is corrected according to the amount of light at the center of the return light from the optical unit And a focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium in accordance with the light quantity of the return light. The light quantity correction means includes the return light from the optical means. A first signal calibrating unit for adjusting the offset of the amount of light, a second signal calibrating unit for adjusting the offset of the amount of light at the center of the return light from the optical means, and a reference voltage setting unit for setting a predetermined voltage value And the reference voltage setting section An arithmetic unit that divides the predetermined voltage value determined by the voltage value of the light quantity at the center whose offset is adjusted by the second signal calibration part, and the light quantity of the return light whose offset is adjusted by the first signal calibration part A multiplication unit that obtains a constant value by multiplying the voltage value obtained by the calculation unit and the division value obtained by the calculation unit, and the focus control unit is configured to perform optical recording and optical recording based on the constant value obtained by the multiplication unit. The distance from the signal recording surface of the medium is controlled to be constant.
[0018]
  The signal recording apparatus having such a configuration adjusts the offset of the light quantity of the return light from the optical means by the light quantity correction means, adjusts the offset of the light quantity at the center of the return light from the optical means, Set the voltage value, divide the set predetermined voltage value by the voltage value of the light amount at the center with the offset adjusted, and calculate the voltage value of the light amount of the return light adjusted with the offset and the obtained divided value. The constant value is obtained by multiplication, and the distance between the optical means and the signal recording surface of the optical recording medium is controlled to be constant by the focus control means based on the obtained constant value.
[0019]
  In addition, a signal recording method according to the present invention is a signal recording method for recording a signal on an optical recording medium using near-field light in order to solve the above-described problem, and is close to the signal recording surface of the optical recording medium. The return light from the optical means that is positioned and collects the near-field light by the laser light on the optical recording medium is corrected according to the light amount at the center of the return light, and the optical means according to the light quantity of the return light A signal recording method for performing a focus control for controlling a distance between a signal recording surface of an optical recording medium and adjusting an offset of a light amount of return light from an optical unit, so that a central portion of the return light from the optical unit is adjusted. Adjust the offset of the light amount, set a predetermined voltage value, divide the set predetermined voltage value by the voltage value of the light amount of the central part where the offset is adjusted, and the voltage of the light amount of the return light whose offset is adjusted Multiply the value by the obtained division value Gets a constant value, it performs focus control for controlling a constant distance between the signal recording surface of the optical means and the optical recording medium based on the obtained predetermined value.
[0020]
  According to another aspect of the present invention, there is provided a signal reproducing apparatus for reproducing a signal from an optical recording medium using near-field light in order to solve the above problems. An optical unit that is positioned close to the signal recording surface of the medium and collects near-field light by laser light on the optical recording medium, and the amount of the return light is corrected according to the amount of light at the center of the return light from the optical unit And a focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium in accordance with the light quantity of the return light. The light quantity correction means includes the return light from the optical means. A first signal calibrating unit for adjusting the offset of the amount of light, a second signal calibrating unit for adjusting the offset of the amount of light at the center of the return light from the optical means, and a reference voltage setting unit for setting a predetermined voltage value And the reference voltage setting section An arithmetic unit that divides the set predetermined voltage value by the voltage value of the light quantity at the center whose offset is adjusted by the second signal calibration part, and the light quantity of the return light whose offset is adjusted by the first signal calibration part A multiplication unit that obtains a constant value by multiplying the voltage value obtained by the calculation unit and the division value obtained by the calculation unit, and the focus control unit is configured to perform optical recording and optical recording based on the constant value obtained by the multiplication unit. The distance from the signal recording surface of the medium is controlled to be constant.
[0021]
  The signal reproducing apparatus having such a configuration adjusts the offset of the light amount of the return light from the optical means by the light amount correction means, adjusts the offset of the light amount at the center of the return light from the optical means, Set the voltage value, divide the set predetermined voltage value by the voltage value of the light amount at the center with the offset adjusted, and calculate the voltage value of the light amount of the return light adjusted with the offset and the obtained divided value. Multiplication is performed to obtain a constant value, and focus control is performed by the focus control means to control the distance between the optical means and the signal recording surface of the optical recording medium to be constant based on the obtained constant value.
[0022]
  The signal reproduction method according to the present invention is a signal reproduction method for reproducing a signal from an optical recording medium using near-field light in order to solve the above-mentioned problem. The return light from the optical means for condensing the near-field light by the laser light on the optical recording medium is corrected according to the light amount at the center of the return light, and the optical means and the light are corrected according to the light quantity of the return light. A signal reproduction method for controlling the distance to the signal recording surface of a recording medium, which adjusts the offset of the amount of return light from the optical means and adjusts the offset of the amount of light at the center of the return light from the optical means Then, a predetermined voltage value is set, and the set predetermined voltage value is divided by the voltage value of the light amount of the central portion where the offset is adjusted, and the voltage value of the light amount of the return light whose offset is adjusted is acquired. Multiply the division value to get a constant value Based on the obtained predetermined values performs focus control for controlling a constant distance between the signal recording surface of the optical means and the optical recording medium.
[0023]
  In order to solve the above-described problem, a signal recording apparatus according to the present invention is a signal recording apparatus that records a signal on an optical recording medium using near-field light, a light source that emits laser light, and optical recording. An optical unit that is positioned close to the signal recording surface of the medium and collects near-field light by laser light on the optical recording medium, and automatically controls the laser intensity of the laser light from the light source when recording a signal on the optical recording medium The laser intensity automatic control means, the target value correction means for correcting the control target value according to the intensity of the laser light emitted from the light source for recording the signal on the optical recording medium, and the target value correction means A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium based on the control target value. A signal calibration unit that adjusts the offset of the amount of laser light from the automatically controlled light source, a control target voltage value setting unit that sets the control target voltage value of the focus control means, and a laser whose offset is adjusted by the signal calibration unit A multiplier that multiplies the voltage value of the amount of light by the control target voltage value set by the control target voltage value setting unit and acquires the multiplied target value as a control target value;
[0024]
  The signal recording apparatus having such a configuration adjusts the offset of the light amount of the laser beam from the light source whose laser intensity is automatically controlled by the target value correction unit, sets the control target voltage value in the focus control, and sets the offset Is obtained by multiplying the voltage value of the adjusted laser light amount by the set control target voltage value to obtain a corrected control target value based on the corrected control target value by the focus control means. Then, focus control is performed to control the distance between the optical means and the signal recording surface of the optical recording medium.
[0025]
This signal recording apparatus performs distance control based on a control target value corrected according to the intensity of the laser even when the intensity of the laser light is changed.
[0026]
  In addition, a signal recording method according to the present invention is a signal recording method for recording a signal on an optical recording medium using near-field light in order to solve the above-described problem. The control target value is corrected according to the intensity of the laser light emitted from the light source, and the optical recording medium is positioned close to the signal recording surface of the optical recording medium and the signal recording surface based on the corrected control target value. Is a signal recording method that performs focus control to control the distance to the optical means that condenses near-field light by laser light, and adjusts the offset of the light amount of the laser light from the light source whose laser intensity is automatically controlled Then, the control target voltage value in the focus control is set, and the control target value obtained by correcting the multiplication value by multiplying the voltage value of the laser light quantity with the offset adjusted by the set control target voltage value And acquired, on the basis of the corrected control target value, performs focus control for controlling the distance between the signal recording surface of the optical means and the optical recording medium.
[0027]
This signal recording method performs distance control based on a control target value corrected according to the intensity of the laser even when the intensity of the laser light is changed.
[0028]
  According to another aspect of the present invention, there is provided a signal reproducing apparatus for reproducing a signal from an optical recording medium using near-field light in order to solve the above problems. An optical unit that is positioned close to the signal recording surface of the medium and collects near-field light by laser light on the optical recording medium, and automatically controls the laser intensity of the laser light from the light source when recording a signal on the optical recording medium The laser intensity automatic control means, the target value correction means for correcting the control target value according to the intensity of the laser light emitted from the light source to reproduce the signal from the optical recording medium, and the target value correction means And a focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium based on the control target value. The offset is adjusted by the signal calibration unit that adjusts the offset of the amount of laser light from the light source whose level is automatically controlled, the control target voltage value setting unit that sets the control target voltage value of the focus control means, and the signal calibration unit. A multiplication unit that multiplies the voltage value of the light quantity of the laser light by the control target voltage value set by the control target voltage value setting unit to obtain the control target value obtained by correcting the multiplication value.
[0029]
  The signal reproducing apparatus having such a configuration adjusts the offset of the laser light amount from the light source whose laser intensity is automatically controlled by the target value correcting means, sets the control target voltage value in the focus control, and the offset is Multiply the adjusted laser light amount voltage value and the set control target voltage value to obtain the corrected control target value, and by the focus control means, based on the corrected control target value, The distance between the optical means and the signal recording surface of the optical recording medium is controlled.
[0030]
Even when the intensity of the laser beam is changed, the signal reproducing apparatus performs distance control based on the control target value corrected in accordance with the intensity of the laser.
[0031]
  In addition, a signal reproduction method according to the present invention is a signal reproduction method for reproducing a signal from an optical recording medium using near-field light in order to solve the above-described problem. The control target value is corrected according to the intensity of the laser light emitted from the light source, and the optical recording medium is positioned close to the signal recording surface of the optical recording medium and the signal recording surface based on the corrected control target value. Is a signal reproduction method that performs focus control to control the distance to the optical means for condensing near-field light by laser light, and adjusts the offset of the light amount of the laser light from the light source whose laser intensity is automatically controlled Then, a control target voltage value in focus control is set, and the control value obtained by correcting the multiplication value by multiplying the voltage value of the laser light quantity with the offset adjusted by the set control target voltage value. Gets a value, based on the corrected control target value, performs focus control for controlling the distance between the signal recording surface of the optical means and the optical recording medium.
[0032]
In this signal reproduction method, even when the intensity of laser light is changed, distance control is performed based on a control target value corrected according to the intensity of the laser.
[0033]
  In order to solve the above-described problem, a signal recording apparatus according to the present invention is a signal recording apparatus that records a signal on an optical recording medium using near-field light, a light source that emits laser light, and optical recording. An optical means that is positioned close to the signal recording surface of the medium and collects near-field light by laser light on the optical recording medium, and a target that corrects the control target value in accordance with the amount of light at the center of the return light from the optical means A value correction unit, and a focus control unit that performs distance control between the optical unit and the signal recording surface of the optical recording medium based on the control target value corrected by the target value correction unit, A signal calibration unit that adjusts the offset of the light amount at the center of the return light from the optical unit, a control target voltage value setting unit that sets a control target voltage value of the focus control unit, and a center whose offset is adjusted by the signal calibration unit Part By multiplying the control target voltage value set by the voltage value of the light amount control target voltage value setting unit obtains a control target value obtained by correcting the multiplication value.
[0034]
  In the signal recording apparatus having such a configuration, the offset is adjusted by the target value correcting unit for the light amount at the center of the return light from the optical unit, the control target voltage value in the focus control is set, and the offset is adjusted. Multiplying the voltage value of the light amount of the central portion by the set control target voltage value to obtain this control value as a corrected control target value, and by the focus control means based on the corrected control target value, the optical means The distance between the optical recording medium and the signal recording surface is controlled.
[0035]
This signal recording apparatus performs distance control based on a control target value corrected according to the intensity of the laser even when the intensity of the laser beam is changed, for example.
[0036]
  In addition, a signal recording method according to the present invention is a signal recording method for recording a signal on an optical recording medium using near-field light in order to solve the above-described problem, in the proximity of the signal recording surface of the optical recording medium. The control target value is corrected according to the amount of light at the center of the return light from the optical means for condensing the near-field light by the laser beam on the optical recording medium, and the optical recording medium is corrected based on the corrected control target value. Signal recording method for performing focus control to control the distance between the signal recording surface of the optical device and the optical means, and adjusting the offset of the light amount at the center of the return light from the optical means to control the target voltage value in focus control Is set, and the voltage value of the light quantity at the center with the offset adjusted is multiplied by the set control target voltage value, and this multiplied value is obtained as a corrected control target value.
[0037]
Thereby, the signal recording method performs distance control based on the control target value corrected in accordance with the intensity of the laser even when the intensity of the laser light is changed, for example.
[0038]
  According to another aspect of the present invention, there is provided a signal reproducing apparatus for reproducing a signal from an optical recording medium using near-field light in order to solve the above problems. An optical means that is positioned close to the signal recording surface of the medium and collects near-field light by laser light on the optical recording medium, and a target that corrects the control target value in accordance with the amount of light at the center of the return light from the optical means A value correction unit, and a focus control unit that performs distance control between the optical unit and the signal recording surface of the optical recording medium based on the control target value corrected by the target value correction unit, A signal calibration unit that adjusts the offset of the light amount at the center of the return light from the optical unit, a control target voltage value setting unit that sets a control target voltage value of the focus control unit, and a center whose offset is adjusted by the signal calibration unit By multiplying the voltage value and the control target voltage value control target voltage value set by the setting unit of the quantity of obtaining as a control target value obtained by correcting the multiplication value.
[0039]
  In the signal reproducing apparatus having such a configuration, the target value correction unit adjusts the offset of the light amount at the center of the return light from the optical unit, sets the control target voltage value in the focus control, and the offset is adjusted. Multiplying the voltage value of the light quantity at the center by the set control target voltage value to obtain this control value as a corrected control target value. Based on the control target value corrected by the target value correction means by the focus control means Thus, distance control between the optical means and the signal recording surface of the optical recording medium is performed.
[0040]
Even when the intensity of the laser beam is changed, the signal reproducing apparatus performs distance control based on the control target value corrected in accordance with the intensity of the laser.
[0041]
  The signal reproduction method according to the present invention is a signal reproduction method for reproducing a signal from an optical recording medium using near-field light in order to solve the above-mentioned problem. The control target value is corrected according to the amount of light at the center of the return light from the optical means for condensing the near-field light by the laser beam on the optical recording medium, and the optical recording medium is corrected based on the corrected control target value. A signal reproduction method for performing focus control for controlling the distance between the signal recording surface of the optical device and the optical means, and adjusting a light amount offset at the center of the return light from the optical means to control a target voltage value in focus control Is set, and the voltage value of the light quantity at the center with the offset adjusted is multiplied by the set control target voltage value, and this multiplied value is obtained as a corrected control target value.
[0042]
Thereby, even if the intensity | strength of a laser beam is changed, the signal reproduction | regeneration method performs distance control based on the control target value corrected according to the intensity | strength of the said laser.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, of course, this description does not mean that each means is limited to the description.
[0044]
(1) First embodiment
In the first embodiment, the present invention is applied to a signal recording apparatus as shown in FIG. Specifically, the signal recording apparatus according to the first embodiment is a so-called cutting method in which information is cut and recorded by irradiating the surface of a glass master coated with a resist with a laser beam modulated according to the information. It is a machine.
[0045]
As shown in FIG. 1, the signal recording apparatus according to the first embodiment is positioned close to a laser element 1 serving as a light source that emits laser light and a glass master 200 serving as an irradiated body (optical recording medium). In accordance with the intensity of the laser light emitted from the laser element 1 for recording a signal on the glass master 200, and the optical head 14 as an optical means for condensing the near-field light by the laser light on the glass master 200. An automatic gain control (Auto Gain Control, AGC) circuit 30 serving as a light amount correction means for correcting the light amount of the return light from the optical head 14 is provided. Further, as shown in FIG. 1, the signal recording apparatus has a return light amount (total reflected return light amount S).₂), A focus control device 20 serving as a focus control means for controlling the distance between the optical head 14 and the glass master 200 is provided. The focus control device 20 is a return corrected by the AGC circuit 30. Light intensity S_ThreeAccordingly, the distance between the optical head 14 and the glass master 200 is controlled to be constant.
[0046]
In the signal recording apparatus having such a configuration, the light amount of the return light from the optical head 14 in accordance with the intensity of the laser light emitted from the laser element 1 in order to record the signal on the glass master 200 by the AGC circuit 30. (Total reflection return light quantity S₂) Is corrected, and the distance between the optical head 14 and the glass master 200 is controlled based on the amount of the return light.
[0047]
Hereinafter, it demonstrates in detail along the flow of a laser beam or a signal.
[0048]
In the signal recording apparatus, when a signal is recorded on the glass master 200, it is emitted from the laser element 1 and passes through an electro-optical conversion element (EOM) 2, an analyzer 3 as a polarizing plate, and a beam splitter (BS) 4. The recording laser beam LB1 incident on the acoustooptic device (AOM) 5 is modulated by the AOM5. Specifically, information from the information source 6 is digitized and inputted to the AOM 5 by the recording signal generator 7, and the AOM 5 digitizes the incident recording laser beam LB1 as described above. Modulation is performed according to the recorded information.
[0049]
The laser beam LB2 modulated by the AOM 5 is reflected by the first mirror 8 and becomes a parallel beam through the condenser lens 9 and the collimator lens 10, passes through the polarization beam splitter (PBS) 11, and is λ / 4. Incident on the plate 12.
[0050]
In the λ / 4 plate 12, the incident light is circularly polarized, and this circularly polarized modulated light LB 3 is reflected by the second mirror 13 and is incident on the optical head 14. The optical head 14 irradiates the glass master 200 coated with a resist with a circularly polarized laser beam in a spot shape. The optical head 14 is, for example, a SIL (Solid Immersion Lens) composed of a second group lens. The signal recording apparatus employs SIL for the optical head 14 to further reduce the spot diameter by so-called bleeding using near-field light, thereby enabling signal recording.
[0051]
Here, the focus of the optical head 14 with respect to the glass master 200 is controlled by the focus control device 20, and the distance between the glass master 200 and the optical head 14 is kept constant. As a result, the laser beam LB4 incident on the optical head 14 forms a light spot whose size is controlled to be constant on the glass master 200 coated with a resist. With this light spot, the glass master 200 coated with a resist is cut according to the recording information.
[0052]
The signal recording device performs the following processing for focus control while cutting the glass master 200 in this way.
[0053]
A part of the laser beam LB6 emitted from the laser element 1 used for recording, passed through the EOM 2 and the analyzer 3, and transmitted through the beam splitter 4 is detected by the first photodetector (PD1) 15.
[0054]
The laser beam LB6 incident on the first photodetector (PD1) 15 is converted into an electrical signal here and input to an automatic power control device (hereinafter referred to as APC) 16, and the value is fed back to the EOM2, The laser power output from the laser element 1 is controlled to be constant. As a result, the light amount (signal) S after APC is made constant.₁Is incident on the AGC circuit 30.
[0055]
On the other hand, the totally reflected return light from the optical head 14 with respect to the laser beam LB4 passes through the λ / 4 plate 12 and is converted into linearly polarized light, and then reflected on the reflection surface of the polarization beam splitter 11 and further reflected on the third mirror 17. And is input to the condenser lens 18. The totally reflected return light LB5 that has passed through the condensing lens 18 is condensed on the second photodetector (PD2) 19, and is detected as the light amount of the totally reflected return light LB5 (hereinafter referred to as the totally reflected return light amount). Is done. Total reflected return light amount (signal) S detected here₂Is input to the AGC circuit 30.
[0056]
As described above, the AGC circuit 30 includes the light amount S after APC.₁Are input, and the AGC circuit 30 outputs the light quantity S after APC.₁And total reflection return light quantity S₂The total reflected return light amount S after AGC which does not depend on the power of the above-described laser beam LB1 at the time of recording (hereinafter referred to as recording laser power)._ThreeIs output. The configuration and operation of this AGC circuit 30 will be described in detail later.
[0057]
Total reflection return light quantity S_ThreeIs input to the focus control device 20. The focus control device 20 uses the reference signal generated by the internal constant voltage source as a control target value and uses the total reflected return light amount S after AGC._ThreeAnd the focus control voltage S based on the information._FourIs output. The focus control voltage S_FourIs input to the optical head 14.
[0058]
The optical head 14 is attached to a piezo element, and a focus control voltage S_FourAccordingly, the distance between the optical head 14 and the glass master 200 is controlled by controlling the expansion and contraction of the piezo element. By this focus control, the distance between the optical head 14 and the glass master 200 is always made constant by the AGC circuit 30 without depending on the recording laser power.
[0059]
Next, the AGC circuit 30 that can be said to be a main part of the signal recording apparatus according to the embodiment will be described in detail. As shown in FIG. 2, the AGC circuit 30 includes first and second signal calibration units 31, a reference voltage setting unit 33, an AGC gain calculation unit 34, and a multiplication unit 35. With such a configuration, the AGC circuit 30 allows the total reflected return light amount S to be constant without depending on the recording laser power._ThreeCan be output. First, the principle will be described.
[0060]
First, an outline of focus control performed based on the total reflected return light amount and a preset control target value will be described. That is, this is an outline description of the technique disclosed in the previous application (Japanese Patent Application No. 11-253296) by the applicant of the present application.
[0061]
  As shown in FIG. 3A, the relationship between the total reflected return light amount and the control voltage (PZT voltage) of the piezo element increases as the control voltage of the piezo element increases (between the optical head 14 and the glass master 200). The shorter the distance, the smaller the total reflected return light amount. This is because when the control voltage of the piezo element is increased, the piezo element expands, and the optical head 14 is brought closer to the glass master 200, so that the distance is ½ or less of the wavelength λ, typically 200 nm or less. As a result, the SIL end surface of the optical head 14 is positioned in the near field region of the glass master 200, and evanescent coupling, that is, so-called bleeding from the SIL end surface, occurs between the SIL end surface of the optical head 14 and the glass master 200. This is because it occurs.
[0062]
In the relationship between the total reflected return light amount and the control voltage (PZT voltage) of the piezo element, there is a linear relationship in the region in which the above-described evanescent coupling occurs, and a fixed control target value in this region. Is set. In the focus control, the PZT voltage (focus control voltage S) is drawn so as to be drawn to the control target value set in the area._Four) And the expansion / contraction control of the piezo element is performed based on the value. Thereby, the distance between the optical head 14 and the glass master 200 is made constant.
[0063]
By the way, in such focus control, the following problems occur when the recording laser power fluctuates.
[0064]
As shown in FIG. 3B, when the recording laser power is decreased from the first power to the third power, the total reflected return light amount is reduced overall, but the total reflected return is reduced accordingly. Regarding the relationship between the amount of light and the PZT voltage, the first to third powers are similar to each other. This is because the relationship between the recording laser power and the total reflected return light amount is proportional. For example, such a change (change) in the recording laser power is made when the distance between the optical head 14 and the glass master 200 has changed.
[0065]
In such a case where the power changes from the first power to the third power, the total reflected return light amount also changes accordingly. Therefore, in the focus control for drawing in based on the fixed control target value, the optical head The problem that it becomes impossible to make constant the distance between 14 and the glass original disc 200 arises. As shown in FIGS. 4A and 4B, the relationship between the total reflected return light amount and the piezo element control voltage (PZT voltage) is standardized (standardized or normalized) for the first and third powers. Normalize) and it becomes clear. Here, for example, the standardization is based on the relationship in the second power shown in FIG.
[0066]
As shown in FIGS. 4A to 4C, when the first to third powers are used, the pull-in positions (PZT voltage values) with respect to the control target values are different. This is because the control target value is fixed regardless of the magnitude of the recording laser power. In other words, when the control target value in the focus control device 20 is fixed, changing the recording laser power is equivalent to changing the control target value.
[0067]
In such a case, in the first power, the distance between the optical head 14 (SIL) and the glass master 200 is as shown in FIG. 4D, and in the second power, in FIG. As shown in FIG. 4E, the distance is longer than in the case of the first power. Further, in the third power, as shown in FIG. The distance becomes longer. As described above, when the power is changed from the first power to the third power, this is substantially equivalent to the deviation of the control target value, and the optical head 14 and the glass master 200 are dependent on the recording laser power. The distance between them will fluctuate. Therefore, in near-field recording, the distance between the optical head 14 and the glass master 200 is within the depth of focus, and changing the distance is equivalent to changing the recording laser power. A change in the recording laser power itself and a change in the recording power due to a change in the distance between the optical head 14 and the glass master 200 are combined, and stable recording becomes impossible.
[0068]
  As described above, when focus control is performed using the control target value that is fixed with the total reflected return light amount that varies depending on the recording laser power as the controlled object, the control target value that is substantially deviated is controlled. Therefore, in the present invention, in order to solve this problem, the total reflected return light amount that does not depend on the change in the recording laser power is acquired, and the focus control is performed using a fixed control target value based on the total reflected return light amount. To do.
[0069]
As described above, it is true that the relationship between the output of the recording laser power and the total reflected return light amount shows a direct proportional relationship, and the present invention uses such a relationship to realize such control. . Specifically, the change in the recording laser power is reflected in the total reflected return light amount. In other words, when the recording laser power is increased, the total reflected return light amount is decreased in consideration of the increase, and when the recording laser power is decreased, the total reflected return light amount is increased in consideration of the decrease amount. Let As a result, a total reflected return light amount that does not depend on a change in the recording laser power can be obtained.
[0070]
The above is the principle, and the configuration of the AGC circuit 30 shown in FIG. 2 is a specific configuration for obtaining the total reflected return light amount that does not depend on the change in the recording laser power.
[0071]
The AGC circuit 30 includes a total reflected return light amount S.₂And light quantity S after APC₁Is entered. Here, the total reflected return light amount S₂And the amount of light S after APC₁The relationship is proportional to the relationship as described above. However, the total reflected return light amount S₂And light quantity S after APC₁In some cases, offset voltages may be superimposed on each other, and not necessarily in a direct proportional relationship. Total reflection return light quantity S₂And light quantity S after APC₁Therefore, it is assumed that the relationship between the total reflection return light amount S and the direct reflection relationship is such that the relationship is directly proportional.₂And light quantity S after APC₁Need to be calibrated. The first and second signal calibration units 31 and 32 perform such calibration.
[0072]
In the first signal calibration unit 31, the total reflected return light amount S₂Adjust the gain and offset. Specifically, as shown in FIG. 5, the first signal calibrating unit 31 performs the total reflected return light amount S in step S1.₂When the input to the second photodetector 19 is set to zero in the subsequent step S2, the total reflected return light amount S is adjusted.₂Whether or not becomes zero. The first signal calibrating unit 31 sets the total reflected return light amount S when the input to the second photodetector 19 is set to zero in step S2.₂Until the total reflection return light quantity S in step S1 becomes zero.₂Adjust the offset. The first signal calibrating unit 31 sets the total reflected return light amount S when the input to the second photodetector 19 is zero in step S2.₂When becomes zero, the process proceeds to step S3. By such an offset adjustment, the total reflected return light amount S is detected by the second photodetector 19.₂The offset voltage or the like generated in the circuit of the part that detects the error is removed.
[0073]
The first signal calibration unit 31 includes a total reflection return light amount S.₂After the offset adjustment is completed, in step 3, the total reflected return light amount S₂Adjust the gain to a certain voltage. For example, the first signal calibration unit 31 performs gain adjustment so as to be 1 (Vpp).
[0074]
On the other hand, in the second signal calibration unit 32, the light quantity S after APC₁Adjust the gain and offset. Specifically, as shown in FIG. 6, the second signal calibrating unit 32 determines the light amount S after APC in step S11.₁When the input to the first photodetector 15 is set to zero in the subsequent step S12, the light amount S after APC is adjusted.₁Whether or not becomes zero. The second signal calibrating unit 32 sets the light amount S after APC when the input to the first photodetector 15 is set to zero in step S12.₁The light quantity S after APC in step S11 until becomes zero₁Adjust the offset. Then, the second signal calibrating unit 32 sets the light amount S after APC when the input to the first photodetector 15 is set to zero in step S12.₁When becomes zero, the process proceeds to step S13. By such offset adjustment, an offset voltage or the like generated in a circuit of a portion where the first photodetector 15 detects the laser beam LB6 is removed.
[0075]
The second signal calibrating unit 32 calculates the light amount S after APC.₁After completing the offset adjustment, the first signal calibrating unit 31 performs the total reflected return light amount S in step 13.₂The gain is adjusted so that the value is the same as that for. That is, for example, the second signal calibration unit 32 performs gain adjustment so as to be 1 (Vpp). The output from the second signal calibration unit 32 is input to the AGC gain calculation unit 34.
[0076]
FIG. 7 shows the APC voltage after calibration (the light amount S after APC).₁) And the total reflected light amount after calibration (total reflected return light amount S)₂) Shows the experimental results regarding the relationship. As shown in FIG. 7, both the APC voltage after calibration and the total reflected light amount after calibration have no offset, and the relationship is directly proportional to the origin.
[0077]
The reference voltage setting unit 33 sets a constant voltage of the same voltage for the signal from the first signal calibration unit 31 and the signal from the second signal calibration unit 32. For example, the reference voltage signal unit 33 is set to 1.0 (V). The output voltage from the reference voltage setting unit 33 is input to the AGC gain calculation unit 34.
[0078]
As described above, the output signal of the second signal calibration unit 32 is also input to the AGC gain calculation unit 34.
[0079]
Here, when the signal (voltage value) from the second signal calibration unit 32 input to the AGC gain calculation unit 34 is A and the signal (voltage value) from the reference voltage setting unit 33 is R, the AGC gain calculation is performed. The unit 34 divides the signal R by the signal A to obtain an AGC gain K (= R / A). The AGC gain K obtained by the AGC gain calculation unit 34 is input to the multiplication unit 35.
[0080]
The multiplication unit 35 receives the output signal of the first signal calibration unit 31, and the multiplication unit 35 multiplies the output signal by the AGC gain K. That is, the multiplication unit 35 obtains a value of Y × K = Y × (R / A) where Y is the output signal (voltage value) of the first signal calibration unit 32. This value is the total reflected return light amount S after AGC from the AGC circuit 30._ThreeIs output as
[0081]
  In the present embodiment, as described above, since R = 1.0, the total reflected return light amount S is eventually obtained._ThreeThe value of Y × K is Y / A. In other words, the total reflected return light amount S output from the AGC circuit 30._ThreeIs the input total reflected return light amount S₂Is the light quantity S after APC₁Equivalent to being divided by. Therefore, the total reflected return light amount S₂Is the total reflected return light amount S after AGC which is a value reflecting the change in the recording laser power in the AGC circuit 30._ThreeIt is said. That is, when the recording laser power is increased, the total reflected return light amount S₂Is reduced in consideration of the increase, and when the recording laser power is reduced, the total reflected return light amount S is reduced.₂Is considered to have increased in consideration of the decrease. Thereby, the gain of the total reflected return light amount is automatically adjusted, and the dependency of the recording laser power is avoided.
[0082]
Here, the processing in the AGC gain 30 will be described using specific values with reference to FIGS. 8 and 9.
[0083]
FIG. 8 shows the relationship between the total reflected return light amount and the PZT voltage for the first to fourth powers having different recording laser powers, as shown in FIG. For example, when the second power is the reference power and the first power is 1.5 times the second power, the total reflected return light amount after the calibration at the first power (the first signal calibration) The maximum value (hereinafter referred to as a representative value) of the output from the unit 31 is 1.5 (V). Therefore, since the total reflected return light amount after calibration at the second power is 1.0 (V), the total reflected return light amount is also 1 when the power is 1.5 times the second power. .5 times as large. Similarly, when the third power is 0.7 times the second power, the maximum total reflected return light amount after calibration at the third power (hereinafter, this is used as a representative value). Indicates 0.7 (V). Therefore, when the power is 0.7 times the second power, the total reflected return light amount can be obtained as 0.7 times as large. Similarly, when the fourth power is 0.6 times the second power, the maximum total reflected return light amount after calibration at the fourth power (hereinafter, this is used as a representative value). Indicates 0.2 (V). Therefore, when the power is 0.2 times the second power, the total reflected return light amount can be obtained as 0.2 times as large. At the fourth power, the total reflected return light amount is less than the control target amount.
[0084]
When the total reflected return light amount after calibration of each power is normalized, as shown in FIGS. 9A to 9D, the relationship between the total reflected return light amount and the control target value is different. become. In such a relationship, as described above, focus control that makes the distance between the optical head 14 and the glass master 200 constant is impossible. In particular, the fourth power, which is the total reflected return light amount that is originally lower than the control target value, cannot even be drawn to the control target value.
[0085]
Even with such total reflected return light amount, the AGC unit 30 can obtain the total reflected return light amount after AGC which is set to a constant value as follows.
[0086]
In the case of the first power (A = 1.5), the total reflected return light amount after calibration is 1.5 (V), and is therefore given by Y × (R / A) by the processing in the AGC circuit 30. Total reflected return light amount S after AGC_ThreeIs 1.5 × (1.0 / 1.5) = 1.0. This is the same value as the total reflected return light amount of the second power as the reference laser power. Similarly, in the case of the third power (A = 0.7), the total reflected return light amount after calibration is 0.7 (V), but the total reflected return light amount S after AGC is used._ThreeIs 0.7 × (1.0 / 0.7) = 1.0. Similarly, in the case of the fourth power (A = 0.2), the total reflected return light amount after calibration is 0.2 (V), but the total reflected return light amount S after AGC is used._ThreeIs 0.2 × (1.0 / 0.2) = 1.0.
[0087]
As can be seen from the above specific examples, even when the laser power is changed, the relative relationship between the control target value and the total reflected return light amount is the same as the relationship in the case of the second power as the reference power. Thus, the AGC unit 30 can obtain a total reflected return light amount that does not depend on the recording laser power.
[0088]
Total reflected return light quantity S₂In order to avoid the dependence on the recording laser power, the total reflected return light amount S directly₂Using AGC, total reflected return light amount S by AGC_ThreeIs not 1 / Y, and signal A that is directly proportional to signal Y is used as Y / A. Signal Y varies depending on the distance between optical head 14 and glass master 200. This is because automatic gain adjustment cannot be performed correctly. And the light quantity S after one APC₁Does not depend on the distance between the optical head 14 and the glass master 200, and always reflects the total reflected return light amount S.₂Therefore, as Y / A, the distance between the optical head 14 and the glass master 200 and the light amount S after APC are expressed as Y / A.₁Without depending on the total reflected return light amount S after AGC_ThreeCan be made constant.
[0089]
In FIG. 10, APC power (S₁) And total reflected return light amount after AGC (S_Three) Shows an example of the relationship. Even when the APC power is increased or decreased as shown in (A) of FIG. 10, the total reflected return light amount after AGC can be obtained as constant as shown in (B) of FIG.
[0090]
In the first embodiment, the case where the present invention is applied to a so-called cutting machine has been described. However, the present invention is not limited to this. That is, the present invention can also be applied to a signal recording device (a signal recording device used on the user side), a signal reproducing device, or a recording and reproducing device.
[0091]
In this case, the signal reproducing apparatus is a signal reproducing apparatus that reproduces a signal from an optical recording medium using near-field light, and basically has an optical system similar to that of the signal recording apparatus shown in FIG. Configured. That is, the signal reproducing apparatus includes a laser element 1 that emits laser light, an optical head 14 that is positioned in proximity to a signal recording surface of an optical recording medium (for example, an optical disk), and that collects near-field light from the laser light on the optical disk; The AGC circuit 30 that corrects the amount of return light from the optical head 14 according to the intensity of the laser light emitted from the laser element 1 to reproduce the signal from the optical disk, and the return corrected by the AGC circuit 30 A focus control device 20 is provided for controlling the distance between the optical head and the signal recording surface of the optical disc to be constant according to the amount of light.
[0092]
In the signal reproducing apparatus having such a configuration, the amount of return light from the optical head 14 according to the intensity of the laser beam emitted from the laser element 1 to reproduce the signal of the optical disk by the AGC circuit 30 (total Reflected return light quantity S₂) Is corrected, and the distance between the optical head 14 and the optical disk is controlled based on the amount of the return light.
[0093]
(2) Second embodiment
In the second embodiment, as shown in FIG. 11, the present invention is applied to a signal recording apparatus as in the first embodiment. Specifically, a glass coated with a resist is used. This is applied to a so-called cutting machine in which information is cut and recorded by irradiating the surface of the master with a laser beam modulated according to the information.
It is.
[0094]
In the signal recording of the second embodiment, the laser element 1 that emits laser light and the optical head 14 that is positioned in proximity to the glass master 200 and collects near-field light by the laser light on the glass master 200, the optical head 14 The AGC circuit (hereinafter referred to as a second AGC circuit) 50 that corrects the light quantity of the return light in accordance with the light quantity at the center of the return light from the light and the return light corrected by the second AGC circuit 50 And a focus control device 20 that controls the distance between the optical head 14 and the glass master 200 to be constant according to the amount of light.
[0095]
In the signal recording apparatus having such a configuration, the second AGC circuit 50 corrects the light amount of the return light in accordance with the light amount of the central portion of the return light from the optical head 14, and the light amount of the return light is corrected. Based on this, the distance between the optical head 14 and the glass master 200 is controlled.
[0096]
Hereinafter, each part is demonstrated along the flow of a laser beam or a signal. In the signal recording apparatus of the second embodiment, the same components as those of the signal recording apparatus of the first embodiment shown in FIG. As long as the processing is the same as that of the signal recording apparatus of the first embodiment described above.
[0097]
In the signal recording apparatus according to the second embodiment, a second beam splitter (BS) 41 is disposed on the optical path of the laser light (return light from the optical head 14) reflected by the third mirror 17. . The return light is branched into two optical paths by the second beam splitter 41. A mask for masking the center of the optical path (hereinafter referred to as a center mask) 42 is disposed on one branch optical path, and a mask for masking other than the center of the optical path (hereinafter referred to as an outer peripheral mask) is disposed on the other branch optical path. 43) is arranged.
[0098]
The total reflected return light LB7 branched at the second beam splitter 41 and masked at the center by the center mask 42 (not transmitted) is condensed by the second condenser lens 18 and is collected by the second photodetector. 19, the total reflected return light quantity S₂Detected as
[0099]
Here, the total reflected return light is light incident at a high NA among the laser light incident on the optical head 14, and is reflected light having a high NA component. Therefore, by arranging the center mask 42 at the center of the optical path, the total reflected return light detected by the second photodetector 19 is extracted from the total reflected component of the return light.
[0100]
On the other hand, the total reflected return light LB8 branched by the second beam splitter 41 and masked (not transmitted) by the outer peripheral mask 43 is transmitted to the third photodetector 46 by the third condenser lens 44. And condensed. As a result, the third photodetector 46 has a light amount of return light at the central portion (hereinafter referred to as a central light return light amount) S._FiveIs detected.
[0101]
Center light return light quantity S_FiveIs a return light of the light incident on the laser beam LB4 incident on the optical head 14 at a low NA, and even if the area between the optical head 14 and the glass master 200 is a near field region, no evanescent coupling occurs. Is. That is, the central light return light quantity S_FiveIs the light amount S after APC described above.₁Similarly, the distance between the optical head 14 and the glass master 200 does not depend on the distance. And the central light return light quantity S_FiveIs the light quantity S after APC₁Similar to the total reflected return light amount S₂Is proportional to For this reason, the signal recording apparatus according to the second embodiment has the light amount S after APC as described above.₁Instead of using the center light return light quantity S._FiveAs in the signal recording apparatus of the embodiment shown in FIG.₂Of AGC. The signal recording apparatus according to the second embodiment includes a second AGC circuit 50 as a part for performing the processing.
[0102]
The second AGC circuit 50 is configured to perform substantially the same processing as the AGC circuit (hereinafter referred to as the first AGC circuit) 30 of the signal recording apparatus of the first embodiment described above. Total reflection return light quantity S₂The center light return light quantity S_FiveDivide by Note that the second AGC circuit 50 includes a signal calibration unit, a reference signal setting unit, and the like as necessary, as with the first AGC circuit 30.
[0103]
The signal recording apparatus according to the second embodiment includes the second AGC circuit 50 as described above, so that it is used as a controlled amount of focus control similarly to the signal recording apparatus according to the first embodiment. Total reflection return light quantity S_ThreeCan be avoided depending on the recording laser power.
[0104]
In the second embodiment, the case where the present invention is applied to a so-called cutting machine has been described. However, the present invention is not limited to this. That is, the present invention can also be applied to a signal recording device (a signal recording device used on the user side), a signal reproducing device, or a recording and reproducing device.
[0105]
In this case, for example, the signal reproducing apparatus is a signal reproducing apparatus that reproduces a signal from an optical recording medium using near-field light, and basically has an optical system similar to the signal recording apparatus shown in FIG. It is configured. That is, the signal reproducing apparatus includes a laser element 1 that emits laser light, an optical head 14 that is positioned in proximity to a signal recording surface of an optical recording medium (for example, an optical disk), and that collects near-field light from the laser light on the optical disk; The second AGC circuit 50 corrects the light quantity of the return light according to the light quantity at the center of the return light from the optical head 14 and the light quantity of the return light corrected by the second AGC circuit 50. And a focus control device 20 for controlling the distance between the optical head and the signal recording surface of the optical disc to be constant.
[0106]
In the signal reproducing apparatus having such a configuration, the second AGC circuit 50 corrects the light amount of the return light in accordance with the light amount of the central portion of the return light from the optical head 14, and the light amount of the return light is corrected. Based on this, the distance between the optical head 14 and the optical disk is controlled.
[0107]
(3) Third embodiment
In the third embodiment, as shown in FIG. 12, the present invention is applied to a signal recording apparatus as in the first embodiment. Specifically, a glass coated with a resist is used. This is applied to a so-called cutting machine in which information is cut and recorded by irradiating the surface of the master with a laser beam modulated according to the information.
[0108]
In the signal recording apparatuses of the first and second embodiments described above, the control target value is fixed, and the total reflected return light amount S with respect to the change of the recording laser power.₂By automatically adjusting the gain, the dependence on the recording laser power was avoided. The signal recording apparatus according to the third embodiment does not fix the control target value, but adapts (changes) the recording laser power to change so that the total reflected return light amount S₂The dependence on the recording laser power is avoided.
[0109]
The signal recording apparatus according to the third embodiment includes a laser element 1 that emits laser light, an optical head 14 that is positioned close to the glass master 200 and focuses near-field light from the laser light on the glass master 200, and glass. An AGC circuit (hereinafter referred to as a third AGC circuit) serving as target value correction means for correcting the control target value in accordance with the intensity of the laser beam emitted from the laser element 1 for recording a signal on the master 200. 60 and a focus control device 20 that controls the distance between the optical head 14 and the glass master 200 based on the control target value corrected by the third AGC circuit 60.
[0110]
The signal recording apparatus having such a configuration corrects the control target value by the third AGC circuit 60 in accordance with the intensity of the laser beam emitted from the laser element 1 in order to record the signal on the glass master 200, Based on the control target value corrected by the third AGC circuit 60, the focus control device 20 performs distance control between the optical head 14 and the glass master 200.
[0111]
Hereinafter, each part is demonstrated along the flow of a laser beam or a signal. In the signal recording apparatus of the third embodiment, the same components as those of the signal recording apparatus of the first embodiment shown in FIG. As long as the processing is the same as that of the signal recording apparatus of the first embodiment described above.
[0112]
The signal recording apparatus according to the third embodiment has a light quantity S after APC.₁In the third AGC circuit 60 to which is inputted, a process of adapting (changing) the control target value to the change of the recording laser power is performed. For example, as shown in FIG. 13, the third AGC circuit 60 includes a signal calibration unit 61, a control target value setting unit 62, and a multiplication unit 63.
[0113]
The signal calibrating unit 61 performs the same process as the first signal calibrating unit 31 shown in FIG.₁Offset adjustment and gain adjustment are performed. The light amount after APC subjected to signal calibration in the signal calibration unit 61 is output to the multiplication unit 63.
[0114]
On the other hand, the control target value setting unit 62 sets the control target voltage of the focus control device 20. Then, the control target voltage set in the control target value setting unit 62 is output to the multiplication unit 63.
[0115]
  The multiplication unit 63 multiplies the signal from the control target value setting unit 62 and the signal from the signal calibration unit 61. That is, the output signal from the control target value setting unit 62 is R₂When the output signal from the signal calibration unit 61 is Y, the multiplication unit 63 is Y × R.₂The value is obtained. This value is the control target value S after the AGC from the third AGC circuit 60.₆(R₂′). That is, R₂′ = Y × R₂
  Thereby, for example, when the recording laser power is changed from the current state and the light amount after APC (calibration value) becomes Y times Y ′ (ie, Y ′ = n × Y), the control target after AGC value is,
  R₂“= Y’ × R₂= N × Y × R₂
  become. As a result, the ratio between the control target and the amount of light after APC remains unchanged before and after the recording laser power is changed. That means
  R₂"/ Y '= (n * Y * R₂) / N × Y = R₂= R₂'/ Y
  become. As shown by this equation, even if the third AGC circuit 60 changes the recording laser power, a control target value that changes correspondingly can be obtained.
[0116]
The focus control device 20 includes a total reflected return light amount S depending on the change of the recording laser power.₂Is input, but the control target value S after AGC₆Changes according to such a change in the recording laser power.₂Control target value S₆Can be made unchanged (relatively unchanged), so that the focus control device 20 allows the focus control voltage S avoiding dependence on the recording laser power._FourCan be output. As a result, the signal recording apparatus of the third embodiment does not depend on the recording laser power and is similar to the case of the signal recording apparatus of the first embodiment shown in FIG. The distance from the master 200 can be made constant, and stable continuous recording becomes possible.
[0117]
In the third embodiment, the case where the present invention is applied to a so-called cutting machine has been described. However, the present invention is not limited to this. That is, the present invention can also be applied to a signal recording device (a signal recording device used on the user side), a signal reproducing device, or a recording and reproducing device.
[0118]
In this case, for example, the signal reproducing apparatus is a signal reproducing apparatus that reproduces a signal from an optical recording medium using near-field light, and basically has an optical system similar to the signal recording apparatus shown in FIG. It is configured. That is, the signal reproducing apparatus reproduces a signal from the optical element, a laser element 1 that emits laser light, an optical head 14 that is positioned close to the signal recording surface of the optical disk and collects near-field light by the laser light on the optical disk, and the optical disk. Therefore, the optical head 14 is based on the third AGC circuit 60 that corrects the control target value according to the intensity of the laser light emitted from the laser element 1 and the control target value corrected by the third AGC circuit 60. And a focus control device 20 for controlling the distance between the optical disc and the signal recording surface of the optical disc.
[0119]
The signal reproducing apparatus having such a configuration corrects the control target value by the third AGC circuit 60 in accordance with the intensity of the laser beam emitted from the laser element 1 to reproduce the signal from the optical disc, The focus control device 20 controls the distance between the optical head 14 and the glass master 200 based on the control target value corrected by the AGC circuit 60.
[0120]
(4) Fourth embodiment
In the fourth embodiment, as shown in FIG. 14, the present invention is applied to a signal recording apparatus as in the first embodiment. Specifically, glass coated with a resist is used. This is applied to a so-called cutting machine in which information is cut and recorded by irradiating the surface of the master with a laser beam modulated according to the information.
[0121]
The signal recording apparatus according to the fourth embodiment includes a laser element 1 that emits laser light, an optical head 14 that is positioned in proximity to the glass master 200 and focuses near-field light from the laser light on the glass master 200, and An AGC circuit (hereinafter referred to as a fourth AGC circuit) 70 serving as target value correcting means for correcting the control target value in accordance with the amount of light at the center of the return light from the optical head 14, and a fourth AGC circuit. And a focus control device 20 that controls the distance between the optical head 14 and the glass master 200 based on the control target value corrected by 70.
[0122]
In the signal recording apparatus having such a configuration, the control target value is corrected by the fourth AGC circuit 70 in accordance with the amount of light at the center of the return light from the optical head 14, and the fourth AGC circuit 70 corrects the control target value. Based on the control target value, the focus control device 20 controls the distance between the optical head 14 and the glass master 200.
[0123]
The signal recording apparatus according to the second embodiment described above uses the central light return light amount instead of using the return light amount after APC, and the total reflected return light amount S after AGC of the controlled amount._FiveIn addition, the signal recording apparatus of the third embodiment described above uses a target for gain control as a control target value. The signal recording apparatus according to the fourth embodiment can be said to be a signal recording apparatus configured by combining the signal recording apparatus according to the second embodiment and the signal recording apparatus according to the third embodiment.
[0124]
That is, in the signal recording apparatus of the fourth embodiment, the total reflected return light LB7 branched by the second beam splitter 41 and masked at the center by the center mask 42 is transmitted by the second condenser lens 18. The light amount S of the total reflected return light that is collected and reflected by the second photodetector 19.₂Detected as Then, the total reflected return light amount S detected by the second photodetector 19.₂Is input to the focus control device 20.
[0125]
On the other hand, the totally reflected return light LB8 branched at the second beam splitter 41 and masked at the outer peripheral portion by the outer peripheral mask 43 (not transmitted) is reflected on the third photodetector 46 by the third condenser lens 44. Where the central light return light quantity S_FiveDetected as Then, the central light return light amount S detected by the third photodetector 46._FiveIs input to the fourth AGC circuit 70.
[0126]
The fourth AGC circuit 70 performs substantially the same processing as the third AGC circuit 60 of the signal recording apparatus of the third embodiment described above, that is, for example, an output from the control target value setting unit Signal and center light return light quantity S_FiveAnd the control target value S after AGC₇Ask for. Note that the fourth AGC circuit 70 includes a signal calibrating unit and the like as necessary, similarly to the third AGC circuit 60.
[0127]
The signal recording apparatus according to the fourth embodiment includes such a fourth AGC circuit 70, so that the recording laser power can be changed as in the signal recording apparatus according to the third embodiment described above. , A control target value that is unchanged (relatively unchanged with respect to the total reflected return light amount) can be obtained.
[0128]
In the fourth embodiment, the case where the present invention is applied to a so-called cutting machine has been described. However, the present invention is not limited to this. That is, the present invention can also be applied to a signal recording device (a signal recording device used on the user side), a signal reproducing device, or a recording and reproducing device.
[0129]
In this case, for example, the signal reproducing apparatus is a signal reproducing apparatus that reproduces a signal from an optical recording medium using near-field light, and basically has an optical system similar to that of the signal recording apparatus shown in FIG. It is configured. That is, the signal reproducing apparatus includes a laser element 1 that emits laser light, an optical head 14 that is positioned close to the signal recording surface of the optical disk, and that collects near-field light by the laser light on the optical disk, and a return from the optical head 14. A fourth AGC circuit 70 that corrects the control target value according to the amount of light at the center of the light, and a signal recording surface of the optical head 14 and the optical disk based on the control target value corrected by the fourth AGC circuit 70 And a focus control device 20 that controls the distance between the two.
[0130]
The signal recording apparatus having such a configuration corrects the control target value by the fourth AGC circuit 70 in accordance with the amount of light at the center of the return light from the optical head 14 during reproduction, and the fourth AGC circuit. The focus control device 20 controls the distance between the optical head 14 and the optical disk based on the control target value corrected by the circuit 70.
[0131]
The first to fourth embodiments have been described above. The signal recording apparatuses according to the first to fourth embodiments are each provided with an AGC circuit that makes the total reflected return light amount or the control target value independent of the recording laser power, so that the optical head 14 and the glass master 200 It is possible to avoid the dependence on the recording laser power of the distance between the two, and to continuously record on the same glass master by changing the recording laser power. That is, in this system, since it is not necessary to stop the focus control operation every time the intensity of light to be irradiated on the optical recording medium is changed, signal recording (or reproduction) is continuously performed on the optical recording medium. Is possible.
[0132]
Further, with such a system, the distance between the optical head 14 and the optical recording medium is always automatically maintained constant, information can be stably recorded (or reproduced), and the manufacturing is easy and excellent. Can be provided.
[0133]
In the above-described embodiment, the case where the optical head 14 is configured to include the SIL has been described. However, the present invention is not limited to this. For example, the single lens configuration has the same characteristics as the SIL. The optical head 14 can also be configured by a SIM (Solid Immersion Mirror).
[0134]
In the above-described embodiment, it is assumed that the laser power is changed. Specifically, the necessity of the change is as follows. First, the necessity at the time of recording will be described.
[0135]
This is because it is necessary to perform recording with the optimum recording laser power in order to optimize the quality of the reproduced signal (jitter, etc.) and to enable stable reproduction without error. That is, by recording with this optimum recording laser power, it is possible to form pits that minimize intersymbol interference and crosstalk.
[0136]
On the other hand, the optimum recording laser power depends on the material of the recording film, the exposure conditions, and the like. For this reason, in order to know the optimum recording laser power, it is necessary to perform recording with a plurality of recording laser powers and evaluate the reproduction signal in accordance with each recording laser power. For this reason, it is necessary to change the recording laser power during recording.
[0137]
On the other hand, the necessity at the time of reproduction is as follows. The laser power during recording and playback is generally different. For example, if the laser power is the same at the time of recording and at the time of reproduction, data recorded at the time of reproduction may be erased. For this reason, in the recording and reproducing apparatus, it is necessary to change the laser power when switching from recording to reproduction.
[0138]
For example, in such a case, the distance between the optical head 14 and the optical recording medium will be different unless AGC as described above is performed. If the GAP length (distance) is deviated, the near field effect may be diminished in some cases, and the evanescent coupling may be eliminated. Furthermore, since the reproduction laser power is smaller than the recording laser power, the return light amount may not reach the control target value when switching to reproduction, for example, as shown in FIG. Then, focus breaks down. For this reason, it is necessary to change the laser power during reproduction.
[0139]
During reproduction, the laser power may be constant and may not be changed, but the present invention works effectively in such a case. Depending on the state of the recording reflection film (for example, reflectance fluctuation due to unevenness of aluminum thickness), the total reflected return light amount may fluctuate, and a phenomenon similar to that in which the laser power is substantially changed may occur. Even when it is not necessary to change the laser power in this way, if the same phenomenon occurs as when the laser power is substantially changed, the correction of the total reflected return light amount according to the present invention works effectively.
[0140]
In the above-described embodiment, the case where the correction target by the AGC (correction unit) is the total reflected return light amount intended for use in focus control has been described. However, the use of the corrected (fixed) total reflection return light amount is not limited to this. As described above, during reproduction, even if the laser power is constant and does not change, the total reflected return light amount may vary depending on the state of the recording reflective film. In this case, the reproduction signal will fluctuate AC or DC, and tracking will be difficult. In addition, signal reproduction clock reproduction also has many errors. Thus, making the total reflected return light amount constant (correcting) leads to other uses such as suppressing fluctuations in the reproduction signal.
[0141]
【The invention's effect】
The signal recording apparatus according to the present invention includes an optical unit that is positioned close to a signal recording surface of an optical recording medium and focuses near-field light by laser light on the optical recording medium, and a light source for recording a signal on the optical recording medium And a light amount correcting means for correcting the light amount of the return light from the optical means according to the intensity of the laser light emitted from the light source, so that the light amount correcting means emits the light from the light source to record the signal on the optical recording medium. The amount of return light from the optical means can be corrected in accordance with the intensity of the laser beam. Thereby, the signal recording apparatus can obtain a constant return light amount regardless of the intensity of the laser light emitted from the light source.
[0142]
In addition, the signal recording method according to the present invention is positioned close to the signal recording surface of the optical recording medium and emitted from the light source in accordance with the intensity of the laser light emitted from the light source for recording a signal on the optical recording medium. By correcting the return light from the optical means for condensing the near-field light by the laser light on the optical recording medium, a constant return light quantity can be obtained regardless of the intensity of the laser light emitted from the light source.
[0143]
Further, the signal reproducing apparatus according to the present invention is positioned close to the signal recording surface of the optical recording medium, optical means for condensing near-field light by laser light on the optical recording medium, and for reproducing a signal from the optical recording medium A light amount correcting means for correcting the light amount of the return light from the optical means in accordance with the intensity of the laser light emitted from the light source, so that the light amount correcting means reproduces the signal from the optical recording medium. The amount of return light from the optical means can be corrected in accordance with the intensity of the laser light emitted from. Thereby, the signal reproducing apparatus can obtain a constant return light amount regardless of the intensity of the laser light emitted from the light source.
[0144]
Further, the signal reproduction method according to the present invention is located close to the signal recording surface of the optical recording medium in accordance with the intensity of the laser light emitted from the light source to reproduce the signal from the optical recording medium, and is proximate to the laser light. By correcting the return light from the optical means on the optical recording medium that collects the field light, a constant return light amount can be obtained regardless of the intensity of the laser light emitted from the light source.
[0145]
A signal recording apparatus according to the present invention is a signal recording apparatus that records a signal on an optical recording medium using near-field light, is positioned close to the signal recording surface of the optical recording medium, and laser light is applied to the optical recording medium. The optical means for condensing near-field light by the light quantity and the light quantity correction means for correcting the light quantity of the return light according to the light quantity at the center of the return light from the optical means. The light quantity of the return light can be corrected according to the light quantity at the center of the return light from the means. Thereby, the signal recording apparatus can obtain a constant amount of return light regardless of the intensity of the laser light emitted from the light source, for example.
[0146]
In addition, the signal recording method according to the present invention is configured so that the return light from the optical means that is positioned close to the signal recording surface of the optical recording medium and collects near-field light by the laser light on the optical recording medium is centered on the return light. By correcting according to the light quantity of the part, for example, a constant return light quantity can be obtained regardless of the intensity of the laser light emitted from the light source.
[0147]
The signal reproducing apparatus according to the present invention includes an optical unit that is positioned in proximity to a signal recording surface of an optical recording medium and focuses near-field light by laser light on the optical recording medium, and a central portion of return light from the optical unit The light amount correcting means corrects the light amount of the return light according to the light amount of the central portion of the return light from the optical means. can do. Thereby, the signal reproducing apparatus can obtain a constant amount of return light regardless of the intensity of the laser light emitted from the light source, for example.
[0148]
In addition, the signal reproduction method according to the present invention is configured so that the return light from the optical means that is positioned close to the signal recording surface of the optical recording medium and collects near-field light by laser light on the optical recording medium is centered on the return light. By correcting according to the light quantity of the part, for example, a constant return light quantity can be obtained regardless of the intensity of the laser light emitted from the light source.
[0149]
Further, the signal recording apparatus according to the present invention is positioned close to the signal recording surface of the optical recording medium, optical means for condensing near-field light by laser light on the optical recording medium, and for recording a signal on the optical recording medium The target value correcting means for correcting the control target value according to the intensity of the laser light emitted from the light source, and the signal recording surface of the optical means and the optical recording medium based on the control target value corrected by the target value correcting means The control target value is corrected by the target value correction means according to the intensity of the laser beam emitted from the light source for recording the signal on the optical recording medium. Then, based on the control target value corrected by the target value correcting means, the distance control between the optical means and the signal recording surface of the optical recording medium can be performed by the focus control means.
[0150]
Thereby, even if the intensity | strength of a laser beam is changed, the signal recording apparatus can perform distance control based on the control target value corrected according to the intensity | strength of the said laser.
[0151]
Further, the signal recording method according to the present invention corrects the control target value according to the intensity of the laser beam emitted from the light source in order to record the signal on the optical recording medium in order to solve the above-described problem, Based on the corrected control target value, the distance control between the signal recording surface of the optical recording medium and the optical means that is positioned close to the signal recording surface and collects near-field light by laser light on the optical recording medium is performed. By doing so, even when the intensity of the laser beam is changed, the distance control can be performed based on the control target value corrected in accordance with the intensity of the laser.
[0152]
Further, the signal reproducing apparatus according to the present invention is positioned close to the signal recording surface of the optical recording medium, optical means for condensing near-field light by laser light on the optical recording medium, and for reproducing a signal from the optical recording medium The target value correcting means for correcting the control target value according to the intensity of the laser light emitted from the light source, and the signal recording surface of the optical means and the optical recording medium based on the control target value corrected by the target value correcting means The control target value is corrected by the target value correction unit according to the intensity of the laser beam emitted from the light source to reproduce the signal from the optical recording medium. Then, based on the control target value corrected by the target value correcting means, the distance control between the optical means and the signal recording surface of the optical recording medium can be performed by the focus control means.
[0153]
Thereby, even when the intensity | strength of a laser beam is changed, the signal reproducing | regenerating apparatus can perform distance control based on the control target value corrected according to the intensity | strength of the said laser.
[0154]
Further, the signal reproduction method according to the present invention corrects the control target value according to the intensity of the laser light emitted from the light source to reproduce the signal from the optical recording medium, and based on the corrected control target value, By controlling the distance between the signal recording surface of the optical recording medium and an optical means that is positioned close to the signal recording surface and collects near-field light by laser light on the optical recording medium, the intensity of the laser light is reduced. Even when the distance is changed, the distance control can be performed based on the control target value corrected according to the intensity of the laser.
[0155]
The signal recording apparatus according to the present invention includes an optical unit that is positioned in proximity to a signal recording surface of an optical recording medium and focuses near-field light by a laser beam on the optical recording medium, and a central portion of return light from the optical unit Based on the target value correcting means for correcting the control target value according to the amount of light, and the control target value corrected by the target value correcting means, the distance control between the optical means and the signal recording surface of the optical recording medium is performed. By providing the focus control means, the control target value is corrected by the target value correction means according to the light amount of the central portion of the return light from the optical means, and based on the control target value corrected by the target value correction means, The distance between the optical means and the signal recording surface of the optical recording medium can be controlled by the focus control means.
[0156]
Thereby, the signal recording apparatus can perform distance control based on the control target value corrected in accordance with the intensity of the laser even when the intensity of the laser light is changed, for example.
[0157]
Further, the signal recording method according to the present invention is in accordance with the amount of light at the center of the return light from the optical means that is positioned close to the signal recording surface of the optical recording medium and collects near-field light by laser light on the optical recording medium. Even if the intensity of the laser beam is changed, for example, by controlling the distance between the signal recording surface of the optical recording medium and the optical means based on the corrected control target value by correcting the control target value. The distance control can be performed based on the control target value corrected in accordance with the intensity of the laser.
[0158]
The signal reproducing apparatus according to the present invention includes an optical unit that is positioned in proximity to a signal recording surface of an optical recording medium and focuses near-field light by laser light on the optical recording medium, and a central portion of return light from the optical unit Based on the target value correcting means for correcting the control target value according to the amount of light, and the control target value corrected by the target value correcting means, the distance control between the optical means and the signal recording surface of the optical recording medium is performed. By providing the focus control means, the control target value is corrected by the target value correction means according to the light amount of the central portion of the return light from the optical means, and based on the control target value corrected by the target value correction means, The focus control means can control the distance between the optical means and the signal recording surface of the optical recording medium.
[0159]
Thereby, even when the intensity | strength of a laser beam is changed, for example, the signal reproducing | regenerating apparatus can perform distance control based on the control target value corrected according to the intensity | strength of the said laser.
[0160]
The signal reproduction method according to the present invention is in accordance with the amount of light at the center of the return light from the optical means that is positioned close to the signal recording surface of the optical recording medium and collects near-field light by laser light on the optical recording medium. Even if the intensity of the laser beam is changed, for example, by controlling the distance between the signal recording surface of the optical recording medium and the optical means based on the corrected control target value by correcting the control target value. The distance control can be performed based on the control target value corrected in accordance with the intensity of the laser.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a signal recording apparatus according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a first AGC circuit of the signal recording apparatus according to the first embodiment.
FIG. 3 is a characteristic diagram showing the relationship between the total reflected return light amount and the PZT voltage used to explain the principle of the present invention.
FIG. 4 is a characteristic diagram showing a relationship between a normalized total reflected return light amount used for explaining the principle of the present invention and a control target value.
FIG. 5 is a flowchart showing a processing procedure of a first signal calibration unit of the first AGC circuit.
FIG. 6 is a flowchart showing a processing procedure of a second signal calibration unit of the first AGC circuit.
FIG. 7 is a characteristic diagram showing the relationship between the calibrated APC voltage and the total reflected light amount in the example.
FIG. 8 is a characteristic diagram showing the relationship between the total reflected return light amount and the control target value used for specifically explaining the effect of the signal recording apparatus of the first embodiment.
FIG. 9 is a characteristic diagram showing the relationship between the normalized total reflected return light amount and the control target value used for specifically explaining the effects of the signal recording apparatus of the first embodiment.
FIG. 10: APC power (S₁) And total reflected return light amount after AGC (S_ThreeFIG.
FIG. 11 is a block diagram showing a configuration of a signal recording apparatus according to a second embodiment of the present invention.
FIG. 12 is a block diagram showing a configuration of a signal recording apparatus according to a third embodiment of the present invention.
FIG. 13 is a block diagram showing a configuration of a third AGC circuit of the signal recording apparatus according to the third embodiment.
FIG. 14 is a block diagram showing a configuration of a signal recording apparatus according to a fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser element, 14 Optical head, 20 Focus control apparatus, 30 1st AGC circuit, 50 2nd AGC circuit, 60 3rd AGC circuit, 70 4th AGC circuit

Claims (26)

In a signal recording apparatus for recording a signal on an optical recording medium using near-field light,
A light source that emits laser light;
Optical means positioned near the signal recording surface of the optical recording medium and condensing near-field light by the laser beam on the optical recording medium;
Laser intensity automatic control means for automatically controlling the laser intensity of the laser light from the light source when recording a signal on the optical recording medium;
A light amount correcting means for correcting the light amount of the return light from the optical means according to the intensity of the laser light emitted from the light source for recording a signal on the optical recording medium;
A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium in accordance with the amount of the return light;
The light quantity correction means includes a first signal calibration unit that adjusts an offset of the light quantity of the return light from the optical means, and the laser light from the light source whose laser intensity is automatically controlled by the laser intensity automatic control means. A second signal calibrating unit that adjusts an offset of the light amount; a reference voltage setting unit that sets a predetermined voltage value; and the predetermined voltage value set by the reference voltage setting unit by the second signal calibrating unit. An arithmetic unit that divides by the voltage value of the light amount of the laser light whose offset is adjusted, and a voltage value of the light amount of the return light whose offset is adjusted by the first signal calibration unit and the division obtained by the arithmetic unit A multiplication unit that multiplies the value to obtain a constant value,
The signal recording apparatus, wherein the focus control unit controls the distance between the optical unit and the signal recording surface of the optical recording medium to be constant based on the constant value acquired by the multiplication unit.   The first signal calibrating unit adjusts the gain of the amount of return light from the optical unit, and the second signal calibrating unit uses the light source whose laser intensity is automatically controlled by the laser intensity automatic control unit. The signal recording apparatus according to claim 1, wherein the gain of the laser light amount is adjusted to be the same value as the gain adjusted by the first signal calibration unit.   The signal recording apparatus according to claim 1, wherein the light quantity correction unit standardizes a light quantity of return light from the optical unit with respect to a control target value by acquiring the constant value.   The signal recording apparatus according to claim 1, wherein the optical recording medium is a cutting apparatus that is a recording medium master.   The signal recording apparatus according to claim 1, wherein the optical means includes a SIL (Solid Immersion Lens) or a SIM (Solid Immersion Mirror). In a signal recording method for recording a signal on an optical recording medium using near-field light, the signal of the optical recording medium is selected according to the intensity of laser light emitted from a light source for recording the signal on the optical recording medium. Correcting the return light from the optical means that is positioned close to the recording surface and condenses the near-field light by the laser light emitted from the light source onto the optical recording medium, and according to the amount of the return light, the optical means and A signal recording method for performing focus control for controlling a distance between the signal recording surface of the optical recording medium,
Adjusting the offset of the light amount of the return light from the optical means, adjusting the offset of the light amount of the laser light from the light source whose laser intensity is automatically controlled, setting a predetermined voltage value, and setting the set Divide the predetermined voltage value by the voltage value of the laser light quantity with the offset adjusted, and multiply the voltage value of the return light quantity with the offset adjusted by the division value to obtain a constant value And a signal recording method for performing focus control for controlling the distance between the optical means and the signal recording surface of the optical recording medium to be constant based on the acquired constant value. In a signal reproducing apparatus for reproducing a signal from an optical recording medium using near-field light,
A light source that emits laser light;
Optical means positioned near the signal recording surface of the optical recording medium and condensing near-field light by the laser beam on the optical recording medium;
Laser intensity automatic control means for automatically controlling the laser intensity of the laser light from the light source when recording a signal on the optical recording medium;
A light amount correcting means for correcting the light amount of the return light from the optical means according to the intensity of the laser light emitted from the light source to reproduce a signal from the optical recording medium;
A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium in accordance with the amount of the return light;
The light quantity correction means includes a first signal calibration unit that adjusts an offset of the light quantity of the return light from the optical means, and the laser light from the light source whose laser intensity is automatically controlled by the laser intensity automatic control means. A second signal calibrating unit that adjusts an offset of the light amount; a reference voltage setting unit that sets a predetermined voltage value; and the predetermined voltage value set by the reference voltage setting unit by the second signal calibrating unit. An arithmetic unit that divides by the voltage value of the light amount of the laser light whose offset is adjusted, and a voltage value of the light amount of the return light whose offset is adjusted by the first signal calibration unit and the division obtained by the arithmetic unit A multiplication unit for multiplying the value to obtain a constant value,
The focus control means is a signal reproducing apparatus that controls the distance between the optical means and the signal recording surface of the optical recording medium to be constant based on the constant value obtained by the multiplier. In a signal reproduction method for reproducing a signal from an optical recording medium using near-field light,
According to the intensity of the laser beam emitted from the light source for reproducing the signal from the optical recording medium, the optical recording medium is positioned close to the signal recording surface, and the optical recording medium is irradiated with the near-field light by the laser beam. A signal reproduction method for performing focus control for correcting the return light from the optical means for condensing and controlling the distance between the optical means and the signal recording surface of the optical recording medium according to the amount of the return light. There,
The amount of the laser light from the light source in which the laser intensity of the laser light from the light source is automatically controlled when adjusting the offset of the amount of return light from the optical means and recording a signal on the optical recording medium. The offset is adjusted, a predetermined voltage value is set, the predetermined voltage value is divided by the voltage value of the light amount of the laser beam with the offset adjusted, and the light amount of the return light with the offset adjusted A focus control for obtaining a constant value by multiplying the voltage value and the division value, and controlling the distance between the optical means and the signal recording surface of the optical recording medium to be constant based on the obtained constant value. A signal reproduction method to perform. In a signal recording apparatus for recording a signal on an optical recording medium using near-field light,
A light source that emits laser light;
Optical means positioned near the signal recording surface of the optical recording medium and condensing near-field light by the laser beam on the optical recording medium;
A light amount correcting means for correcting the light amount of the return light in accordance with the light amount of the central portion of the return light from the optical means;
A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium in accordance with the amount of the return light;
The light amount correction means includes a first signal calibration unit that adjusts an offset of the light amount of the return light from the optical means, and a second signal calibration that adjusts an offset of the light amount at the center of the return light from the optical means. Unit, a reference voltage setting unit for setting a predetermined voltage value, and the predetermined voltage value set by the reference voltage setting unit for the amount of light at the central part whose offset is adjusted by the second signal calibration unit. A constant value is obtained by multiplying the arithmetic unit that divides by the voltage value, the voltage value of the amount of the return light whose offset is adjusted by the first signal calibration unit, and the division value obtained by the arithmetic unit. A multiplication unit,
The signal recording apparatus, wherein the focus control unit controls the distance between the optical unit and the signal recording surface of the optical recording medium to be constant based on the constant value acquired by the multiplication unit.   The first signal calibration unit adjusts the gain of the light amount of the return light from the optical means, and the second signal calibration unit adjusts the gain of the light amount at the center of the return light from the optical means. The signal recording apparatus according to claim 9, wherein the signal recording apparatus is adjusted so as to have the same value as the gain adjusted by the signal calibrating unit.   The signal recording apparatus according to claim 9, wherein the light amount correction unit standardizes a light amount of return light from the optical unit with respect to a control target value by acquiring the constant value.   10. The signal recording apparatus according to claim 9, further comprising laser intensity automatic control means for automatically controlling the laser intensity of the laser light from the light source when recording a signal on the optical recording medium. In a signal recording method for recording a signal on an optical recording medium using near-field light, an optical means that is positioned close to the signal recording surface of the optical recording medium and collects near-field light by laser light on the optical recording medium The return light from the focus is corrected according to the amount of light at the center of the return light, and the distance between the optical means and the signal recording surface of the optical recording medium is controlled according to the amount of the return light. A signal recording method for performing control,
Adjusting the offset of the light quantity of the return light from the optical means, adjusting the offset of the light quantity at the center of the return light from the optical means, setting a predetermined voltage value, and setting the predetermined voltage value Is divided by the voltage value of the light amount at the center with the offset adjusted, and the constant value is obtained by multiplying the voltage value of the light amount of the return light with the offset adjusted and the obtained division value. A signal recording method for performing focus control for controlling the distance between the optical means and the signal recording surface of the optical recording medium to be constant based on the acquired constant value. In a signal reproducing apparatus for reproducing a signal from an optical recording medium using near-field light,
A light source that emits laser light;
Optical means positioned near the signal recording surface of the optical recording medium and condensing near-field light by the laser beam on the optical recording medium;
A light amount correcting means for correcting the light amount of the return light in accordance with the light amount of the central portion of the return light from the optical means;
A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium in accordance with the amount of the return light;
The light amount correction means includes a first signal calibration unit that adjusts an offset of the light amount of the return light from the optical means, and a second signal calibration that adjusts an offset of the light amount at the center of the return light from the optical means. Unit, a reference voltage setting unit for setting a predetermined voltage value, and the predetermined voltage value set by the reference voltage setting unit for the amount of light at the central part whose offset is adjusted by the second signal calibration unit. A constant value is obtained by multiplying the arithmetic unit that divides by the voltage value, the voltage value of the amount of the return light whose offset is adjusted by the first signal calibration unit, and the division value obtained by the arithmetic unit. A multiplication unit,
The focus control means is a signal reproducing apparatus that controls the distance between the optical means and the signal recording surface of the optical recording medium to be constant based on the constant value acquired by the multiplier. In a signal reproducing method for reproducing a signal from an optical recording medium using near-field light, an optical means that is positioned close to the signal recording surface of the optical recording medium and collects near-field light by laser light on the optical recording medium The return light from the focus is corrected according to the amount of light at the center of the return light, and the distance between the optical means and the signal recording surface of the optical recording medium is controlled according to the amount of the return light. A signal reproduction method for performing control,
Adjusting the offset of the light quantity of the return light from the optical means, adjusting the offset of the light quantity at the center of the return light from the optical means, setting a predetermined voltage value, and setting the predetermined voltage value Is divided by the voltage value of the light amount at the center with the offset adjusted, and the constant value is obtained by multiplying the voltage value of the light amount of the return light with the offset adjusted and the obtained division value. A signal reproduction method for performing focus control for controlling the distance between the optical means and the signal recording surface of the optical recording medium to be constant based on the acquired constant value. In a signal recording apparatus for recording a signal on an optical recording medium using near-field light,
A light source that emits laser light;
Optical means positioned near the signal recording surface of the optical recording medium and condensing near-field light by the laser beam on the optical recording medium;
Laser intensity automatic control means for automatically controlling the laser intensity of the laser light from the light source when recording a signal on the optical recording medium;
Target value correcting means for correcting the control target value according to the intensity of the laser light emitted from the light source for recording a signal on the optical recording medium;
A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium based on the control target value corrected by the target value correction means;
The target value correcting means includes a signal calibrating unit for adjusting an offset of the light amount of the laser light from the light source whose laser intensity is automatically controlled by the laser intensity automatic control means, and a control target voltage value of the focus control means. A control target voltage value setting unit to be set, a voltage value of the light amount of the laser light whose offset is adjusted by the signal calibration unit, and the control target voltage value set by the control target voltage value setting unit. A signal recording apparatus comprising: a multiplication unit that obtains the multiplication value as the corrected control target value.   17. The signal recording apparatus according to claim 16, wherein the signal calibration unit adjusts the gain of the light amount of the laser light from the light source whose laser intensity is automatically controlled by the laser intensity automatic control means. In a signal recording method for recording a signal on an optical recording medium using near-field light, the control target value is corrected according to the intensity of the laser light emitted from the light source in order to record the signal on the optical recording medium. Based on the corrected control target value, between the signal recording surface of the optical recording medium and an optical means that is positioned close to the signal recording surface and focuses the near-field light by the laser beam on the optical recording medium A signal recording method for performing focus control for controlling the distance of
Adjust the offset of the laser light amount from the light source whose laser intensity is automatically controlled, set the control target voltage value in focus control, and set the voltage value and the setting of the laser light amount with the offset adjusted Is multiplied by the control target voltage value thus obtained to obtain the multiplied control value as the corrected control target value. Based on the corrected control target value, the optical means and the signal recording surface of the optical recording medium A signal recording method for performing focus control for controlling the distance between the two. In a signal reproducing apparatus for reproducing a signal from an optical recording medium using near-field light,
A light source that emits laser light;
Optical means positioned near the signal recording surface of the optical recording medium and condensing near-field light by the laser beam on the optical recording medium;
Laser intensity automatic control means for automatically controlling the laser intensity of the laser light from the light source when recording a signal on the optical recording medium;
Target value correcting means for correcting the control target value according to the intensity of the laser light emitted from the light source to reproduce a signal from the optical recording medium;
A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium based on the control target value corrected by the target value correction means;
The target value correcting means includes a signal calibrating unit for adjusting an offset of the light amount of the laser light from the light source whose laser intensity is automatically controlled by the laser intensity automatic control means, and a control target voltage value of the focus control means. A control target voltage value setting unit to be set, a voltage value of the light amount of the laser light whose offset is adjusted by the signal calibration unit, and the control target voltage value set by the control target voltage value setting unit. A signal reproducing device having a multiplication unit that acquires the multiplication value as the corrected control target value. In a signal reproduction method for reproducing a signal from an optical recording medium using near-field light, the control target value is corrected in accordance with the intensity of the laser beam emitted from the light source to reproduce the signal from the optical recording medium. Based on the corrected control target value, between the signal recording surface of the optical recording medium and an optical means that is positioned close to the signal recording surface and focuses the near-field light by the laser beam on the optical recording medium A signal reproduction method for performing focus control for controlling the distance of
Adjust the offset of the amount of laser light from the light source whose laser intensity is automatically controlled, set the control target voltage value in the focus control, and the voltage value of the amount of laser light and the offset adjusted Multiplying the set control target voltage value to obtain the multiplied value as the corrected control target value, and based on the corrected control target value, the optical means and the signal recording surface of the optical recording medium, A signal reproduction method for performing focus control for controlling the distance between the two. In a signal recording apparatus for recording a signal on an optical recording medium using near-field light,
A light source that emits laser light;
Optical means positioned near the signal recording surface of the optical recording medium and condensing near-field light by the laser beam on the optical recording medium;
Target value correcting means for correcting the control target value in accordance with the amount of light at the center of the return light from the optical means;
A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium based on the control target value corrected by the target value correction means;
The target value correcting unit includes a signal calibration unit that adjusts an offset of the light amount at the center of the return light from the optical unit, a control target voltage value setting unit that sets a control target voltage value of the focus control unit, and Multiplying the voltage value of the light amount of the central part whose offset is adjusted by the signal calibrating unit and the control target voltage value set by the control target voltage value setting unit, and the multiplied value is used as the corrected control target value. Signal recording device to acquire.   The signal recording apparatus according to claim 21, wherein the signal calibrating unit adjusts a gain of a light amount at a central portion of return light from the optical means.   The signal recording apparatus according to claim 21, further comprising a laser intensity automatic control unit that automatically controls a laser intensity of a laser beam from the light source when a signal is recorded on the optical recording medium. In a signal recording method for recording a signal on an optical recording medium using near-field light, an optical means that is positioned close to the signal recording surface of the optical recording medium and collects near-field light by laser light on the optical recording medium Focus that corrects the control target value in accordance with the light amount of the return light from the center and controls the distance between the signal recording surface of the optical recording medium and the optical means based on the corrected control target value A signal recording method for performing control,
The offset of the light amount at the center of the return light from the optical means is adjusted, the control target voltage value in the focus control is set, the voltage value of the light amount at the center where the offset is adjusted, and the set value A signal recording method for multiplying a control target voltage value and obtaining the multiplied value as the corrected control target value. In a signal reproducing apparatus for reproducing a signal from an optical recording medium using near-field light,
A light source that emits laser light;
Optical means positioned near the signal recording surface of the optical recording medium and condensing near-field light by the laser beam on the optical recording medium;
Target value correcting means for correcting the control target value in accordance with the amount of light at the center of the return light from the optical means;
A focus control means for controlling the distance between the optical means and the signal recording surface of the optical recording medium based on the control target value corrected by the target value correction means;
The target value correction unit includes a signal calibration unit that adjusts an offset of the light amount at the center of the return light from the optical unit, a control target voltage value setting unit that sets a control target voltage value of the focus control unit, and Multiplying the voltage value of the light amount of the central part whose offset is adjusted by the signal calibrating unit and the control target voltage value set by the control target voltage value setting unit, and the multiplied value is used as the corrected control target value. The signal reproduction device to acquire. In a signal reproducing method for reproducing a signal from an optical recording medium using near-field light, an optical means that is positioned close to the signal recording surface of the optical recording medium and collects near-field light by laser light on the optical recording medium A focus that corrects the control target value according to the amount of light at the center of the return light from the light, and controls the distance between the signal recording surface of the optical recording medium and the optical means based on the corrected control target value A signal reproduction method for performing control,
Adjusting the offset of the light quantity at the center of the return light from the optical means, setting the control target voltage value in the focus control, and the voltage value of the light quantity at the center where the offset is adjusted and the set value A signal regeneration method for multiplying a control target voltage value and obtaining the multiplied value as the corrected control target value.

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