JP2010257548A - Optical disk device - Google Patents

Abstract

An optical disc apparatus capable of suppressing deterioration in reproduction characteristics when a focus control target position is changed is provided.
A focus control target position in three states of a reproduction state, a pre-recording state, and a recording state is held in accordance with an operation for performing recording / reproduction with respect to an information carrier, and focus is determined in accordance with a signal from a switching timing generation unit. A focus position changing means for outputting a signal for changing the control target position to the focus error detecting means, and the focus position changing means is a focus control target position before recording according to the fluctuation amount of the condenser lens from the lens position detecting means. To change.
[Selection] Figure 1

Description

  The present invention relates to an optical disc apparatus that changes a focus control target position before recording when recording or reproducing is performed on a disc-shaped information carrier (hereinafter referred to as an optical disc) capable of recording.

  In a conventional optical disk apparatus, when reproducing a signal, a relatively weak light beam with a constant light amount is irradiated onto the optical disk 1 as an information carrier, and reflected light modulated by the optical disk 1 is detected. Further, in the signal recording, the light beam intensity is modulated in accordance with the signal to be recorded, and information is written on the recording material film on the optical disc 1. On the reproduction-only optical disc 1, information by pits is recorded in a spiral shape in advance. The optical disk 1 that can be recorded and reproduced is manufactured by forming a material film that can be optically recorded and reproduced on a substrate surface having a spiral concavo-convex structure track by a technique such as vapor deposition. In order to record information on the optical disc 1 or to reproduce the recorded information, the normal direction of the surface of the optical disc 1 (hereinafter referred to as the focus direction) so that the light beam is always in a predetermined convergence state on the recording material film. ) And tracking control for controlling the optical beam 1 in the radial direction (hereinafter referred to as the tracking direction) so that the light beam is always located on a predetermined track.

  A semiconductor laser 11, a condenser lens 13, a beam splitter 12, an Fc actuator 14, a Tk actuator 15, a spherical aberration generator 16, and a light amount detector 17 are attached to the optical head 10. The light beam generated from the semiconductor laser 11 passes through the beam splitter 12, the amount of spherical aberration is changed by the spherical aberration generator 16, and is converged on the disk-shaped optical disk 1 by the condenser lens 13. The reflected light beam then passes again through the condenser lens 13 and the spherical aberration generator 16, is reflected by the beam splitter 12, and is applied to the light quantity detector 17. The condenser lens 13 is supported by an elastic body (not shown), and moves in the focus direction by an electromagnetic force when a current is passed through the Fc actuator 14. When a current is passed through the Tk actuator 15, it moves in the tracking direction by electromagnetic force. The light quantity detection unit 17 generates a signal corresponding to the detected light quantity.

  The operation of the optical disc apparatus in the prior art will be described with reference to FIGS. FIG. 8 shows a block configuration. FIG. 9a shows an example of a change in the operating state of the optical disc apparatus. FIG. 9 b shows an example of a signal output from the switching timing generation unit 30. FIG. 9 c shows an example of a change in the position of the condenser lens 13. FIG. 9d shows an example of a signal output from the Fc position indicating unit 34.

  In FIG. 8, the light quantity detection unit 17 sends a signal to the FE generation unit 20. The FE generation unit 20 uses the signal of the light amount detection unit 17 to respond to an error signal indicating the convergence state of the light beam on the information surface of the optical disc 1, that is, according to the positional deviation of the focal point of the light beam with respect to the information surface of the optical disc 1. An error signal (hereinafter referred to as FE signal) is calculated and sent to the Fc filter 21. The Fc filter 21 generates a drive for performing focus control according to the FE signal, and sends it to the Fc actuator 14. When recording on the optical disc 1, the switching timing generation unit 30 defines a pre-recording state from a predetermined time before the start of recording to the start of recording, and a signal indicating a reproduction state, a pre-recording state, or a recording state Send to part 34. The pre-recording Fc position generation unit 33 generates a pre-recording Fc position and sends it to the Fc position instruction unit 34. The recording Fc position generation unit 32 generates an Fc position during recording and sends it to the Fc position instruction unit 34. When the signal from the switching timing generation unit 30 is in a reproduction state, the Fc position instruction unit 34 indicates an internal reproduction Fc position, and when the signal from the switching timing generation unit 30 is in a pre-recording state, the pre-recording Fc position generation unit 33. When the signal from the switching timing generation unit 30 is in the recording state, the pre-recording Fc position from the recording Fc position generation unit 32 is sent to the FE generation unit 20. The FE generator 20 changes the focus control target position by applying an offset to the FE signal based on the signal from the Fc position instruction unit 34.

  The wavelength of the light beam from the semiconductor laser 11 varies depending on the emission power. Further, the refractive index of each element in the optical head 10 has wavelength dependency. When the condensing lens 13 is made of resin instead of glass, the refractive index change due to the wavelength change of the light beam is particularly large. Therefore, when the recording light emission is performed by increasing the power from the reproduction light emission, the wavelength of the light beam changes, and the focal position changes due to the wavelength change. In the focus control, the focal point of the light beam is moved by moving the condensing lens 13, but the response is on the order of several kHz, and an appropriate focus state is not obtained during a transient response at the beginning of recording.

  In order to solve the above-described problem, there is a method in which the position of the condenser lens 13 is moved in advance so that an optimum focus state can be obtained at the time of recording, as shown in Patent Document 1, before recording.

  This will be described with reference to FIG. The switching timing generation unit 30 outputs a status signal shown in FIG. 9B in accordance with the operating status of the optical disc 1 shown in FIG. 9A. As shown in FIG. 9d, the Fc position instruction unit 34 records the signal from the switching timing generation unit 30 when the signal from the switching timing generation unit 30 transitions from the reproduction state to the pre-recording state before recording starts. When the transition from the previous state to the recording state is made, the offset of the FE signal is changed. When the signal from the switching timing generation unit 30 is in the reproduction state and the pre-recording state, the semiconductor laser 11 emits a light beam at the reproduction level. By changing the offset of the FE signal when the signal from the switching timing generation unit 30 transitions from the reproduction state to the pre-recording state, the condenser lens 13 is moved to a position where recording should be performed. When the signal from the switching timing generation unit 30 is in a recording state, the semiconductor laser 11 emits a light beam of recording power. By changing the offset of the FE signal when the signal from the switching timing generation unit 30 transitions from the pre-recording state to the recording state, a change factor such as a circuit offset due to recording and reproduction is canceled, and the condenser lens 13 is substantially the same. Let them keep their position.

Japanese Patent Application Laid-Open No. 06-349095

  In this way, by adding an offset to the FE signal in advance before actually recording, the focus state when entering the recording is improved. However, it is unclear how to obtain the offset amount to be added to the FE signal in advance, and the addition of the offset deteriorates the focus state in the reproduction immediately before recording and affects the reproduction operation.

  Since the responsiveness of the condensing lens 13 does not change so much with the double speed, the amount of data to be played back in the focused state that deteriorates as the double speed increases, resulting in garbled data.

  In particular, the Blu-ray disc has a large NA to be used, so that the reproduction signal has a great influence on the deterioration of the focus state.

  In the future, as the price of Blu-ray disc compatible drives will be reduced, it is inevitable that the condensing lens 13 will be made of resin, and countermeasures for this problem are required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical disc apparatus capable of suppressing deterioration in reproduction characteristics when a focus control target position is changed before recording.

  In the optical disc device according to claim 1 of the present invention, the focus error detecting means for detecting a signal corresponding to the positional deviation of the focal point of the light beam with respect to the information surface or surface of the information carrier, and according to the signal of the focus error detecting means, Focus control means for changing the convergence state of the light beam so that the focal point of the light beam follows the information surface of the information carrier, and the reproduction state, the pre-recording state, and the recording according to the operation of recording and reproducing the information carrier The change amount of the condensing lens according to the signal of the switching timing generation means for outputting the three states of the intermediate state and the focus error detection means when the signal from the switching timing generation means transits from the pre-recording state to the recording state. Lens position detection means for output, and focus in three states of a reproduction state, a pre-recording state, and a recording state in accordance with the operation of recording and reproducing information carrier A focus position changing means for holding a target position and outputting a signal for changing the focus control target position in accordance with a signal from the switching timing generating means to the focus error detecting means. The focus position changing means is a lens position detecting means. The focus control target position before recording is changed in accordance with the fluctuation amount of the condenser lens from.

  Furthermore, the optical disk apparatus according to claim 2 of the present invention is characterized by comprising servo parameter changing means for changing servo parameters in a section in which a signal from the switching timing generating means indicates a pre-recording state.

  The optical disk apparatus according to claim 3 of the present invention further comprises track error detecting means for detecting a signal corresponding to the positional deviation between the light beam and the track on the information carrier, and the servo parameter changing means is track error detecting means. The detection gain is changed.

  Furthermore, the optical disk apparatus according to claim 4 of the present invention further comprises track error detecting means for detecting a signal corresponding to the positional deviation between the light beam and the track on the information carrier, and the servo parameter changing means is track error detecting means. The offset is changed.

  Furthermore, the optical disk apparatus according to claim 5 of the present invention is characterized in that the servo parameter changing means changes the application amount of the circuit offset for servo signal detection.

  Further, in the optical disk apparatus according to claim 6 of the present invention, the servo parameter changing means changes the amount of spherical aberration given to the light beam.

  Further, in the optical disc apparatus according to claim 7 of the present invention, the switching is performed according to the transient response settling time of the signal from the focus error detecting means when the signal from the switching timing generating means transits from the reproduction state to the pre-recording state. The timing generation means includes timing change means for changing the timing of transition from the reproduction state to the pre-recording state.

  Furthermore, the optical disc apparatus according to claim 8 of the present invention is characterized in that the focus control means increases the focus control gain when the signal from the switching timing generation means transitions from the reproduction state to the pre-recording state.

  Further, in the optical disc apparatus according to claim 9 of the present invention, the focus control means is configured to output the focus error detection means from the focus error detection means after the signal from the switching timing generation means transits from the reproduction state to the pre-recording state to increase the focus control gain. When the signal is settled, the focus control gain is returned.

  Further, in the optical disc apparatus according to claim 10 of the present invention, the transient response waveform is corrected by, for example, overshooting the signal from the focus position changing unit when the signal from the switching timing generating unit transitions from the reproduction state to the pre-recording state. And a signal correcting means.

  Further, in the optical disk apparatus according to claim 11 of the present invention, the signal correction means is configured to detect the signal from the focus position changing means for a predetermined time after the signal from the switching timing generating means transitions from the reproduction state to the pre-recording state. It is characterized by multiplying the change by a predetermined amount.

  Further, in the optical disc apparatus according to claim 12 of the present invention, the lens position detecting means is a condensing lens according to the signal of the focus error detecting means when the signal from the switching timing generating means transitions from the reproduction state to the pre-recording state. Is output to the signal correction means, and the signal correction means corrects the signal according to the fluctuation amount of the condenser lens from the lens position detection means.

  Further, in the optical disc apparatus according to claim 13 of the present invention, the lens position detecting means collects light according to the signal of the focus error detecting means when the signal from the switching timing generating means transits from the pre-recording state to the recording state. The variation amount of the lens is output to the signal correction unit, and the signal correction unit corrects the signal according to the variation amount of the condenser lens from the lens position detection unit.

  Furthermore, in the optical disk apparatus according to claim 14 of the present invention, when the difference between the reproduction focus control target position held by the focus position changing means and the focus control target position before recording is a predetermined value or more, the recording / reproduction double speed is limited. And a double speed limiting means.

  Furthermore, in the optical disc apparatus according to claim 15 of the present invention, when the difference between the focus control target position for reproduction held by the focus position changing means and the focus control target position before recording is greater than or equal to a predetermined value, the recording and reproduction operations are performed. If the difference between the playback focus control target position held by the focus position changing means and the focus control target position before recording is smaller than a predetermined value, the search operation is performed only during recording to playback. The recording / reproducing operation changing means for entering the operating state is provided.

  Further, in the optical disc apparatus according to claim 16 of the present invention, when the difference between the focus control target position for reproduction held by the focus position changing means and the focus control target position before recording is equal to or larger than a predetermined value, only during the period from recording to reproduction. A search operation is entered, and no recording, playback, or search is performed between playback and recording. The difference between the focus control target position for playback held by the focus position changing means and the focus control target position before recording is smaller than a predetermined value. In this case, there is provided a recording / reproducing operation changing means that enters a search operation only during recording to reproduction and enters an operation state in which continuous operation is performed from reproduction to recording.

  Further, in the optical disc apparatus according to claim 17 of the present invention, the focus position changing means changes the focus control target position before recording according to the average value of the light beam emission power at the time of recording.

  Further, in the optical disk apparatus according to claim 18 of the present invention, the lens position detecting means acquires the signal from the focus error detecting means once at the change timing of the signal from the switching timing generating means.

  Further, in the optical disc apparatus according to claim 19 of the present invention, the lens position detection means acquires the signal from the focus error detection means by integrating for a predetermined time from the change timing of the signal from the switching timing generation means. .

  Further, in the optical disk apparatus according to claim 20 of the present invention, the predetermined time for the integration of the lens position detecting means is a time until the signal from the focus error detecting means is settled.

  In the optical disc device according to claim 1 of the present invention, the focus error detecting means for detecting a signal corresponding to the positional deviation of the focal point of the light beam with respect to the information surface or surface of the information carrier, and according to the signal of the focus error detecting means, Focus control means for changing the convergence state of the light beam so that the focal point of the light beam follows the information surface of the information carrier, and the reproduction state, the pre-recording state, and the recording according to the operation of recording and reproducing the information carrier The change amount of the condensing lens according to the signal of the switching timing generation means for outputting the three states of the intermediate state and the focus error detection means when the signal from the switching timing generation means transits from the pre-recording state to the recording state. Lens position detection means for output, and focus in three states of a reproduction state, a pre-recording state, and a recording state in accordance with the operation of recording and reproducing information carrier A focus position changing means for holding a target position and outputting a signal for changing the focus control target position in accordance with a signal from the switching timing generating means to the focus error detecting means. The focus position changing means is a lens position detecting means. Since the focus control target position before recording is changed in accordance with the fluctuation amount of the condenser lens from, the shift of the focus control target position corresponding to chromatic aberration that changes depending on the recording power, temperature, etc. can be accurately measured.

  Further, the optical disc apparatus according to the second aspect of the present invention includes the servo parameter changing means for changing the servo parameter in the section where the signal from the switching timing generating means indicates the pre-recording state. It is possible to suppress the reproduction characteristic deterioration due to the position change.

  The optical disk apparatus according to claim 3 of the present invention further comprises track error detecting means for detecting a signal corresponding to the positional deviation between the light beam and the track on the information carrier, and the servo parameter changing means is track error detecting means. Therefore, the tracking error signal amplitude deterioration due to the change of the focus control target position immediately before recording can be suppressed.

  Furthermore, the optical disk apparatus according to claim 4 of the present invention further comprises track error detecting means for detecting a signal corresponding to the positional deviation between the light beam and the track on the information carrier, and the servo parameter changing means is track error detecting means. Therefore, the tracking error signal symmetry deterioration due to the change of the focus control target position immediately before recording can be suppressed.

  Further, in the optical disk apparatus according to claim 5 of the present invention, the servo parameter changing means changes the application amount of the servo signal detection circuit offset, so that the influence of the offset change due to the change of the focus control target position immediately before recording is affected. Can be suppressed.

  Further, in the optical disk apparatus according to claim 6 of the present invention, the servo parameter changing means changes the amount of spherical aberration given to the light beam, so that the spherical aberration deviation caused by changing the focus control target position immediately before recording is suppressed. Can do.

  Further, in the optical disc apparatus according to claim 7 of the present invention, the switching is performed according to the transient response settling time of the signal from the focus error detecting means when the signal from the switching timing generating means transits from the reproduction state to the pre-recording state. The timing generator has a timing changing unit that changes the timing of transition from the playback state to the pre-recording state, so that when the focus control target position changes quickly, there is no need for a playback state in which the focus control target position is shifted. Time can be saved.

  Furthermore, in the optical disc apparatus according to claim 8 of the present invention, the focus control means increases the focus control gain when the signal from the switching timing generation means transitions from the reproduction state to the pre-recording state, so that the focus control target position change is settled. The time can be shortened.

  Further, in the optical disc apparatus according to claim 9 of the present invention, the focus control means is configured to output the focus error detection means from the focus error detection means after the signal from the switching timing generation means transits from the reproduction state to the pre-recording state to increase the focus control gain. When the signal is settled, the focus control gain is returned, so that it is possible to reduce an unnecessary increase in residual after the focus control target position change is settled.

  Further, in the optical disc apparatus according to claim 10 of the present invention, the transient response waveform is corrected by, for example, overshooting the signal from the focus position changing unit when the signal from the switching timing generating unit transitions from the reproduction state to the pre-recording state. Since the signal correction means is provided, it is possible to shorten the settling time of the focus control target position change.

  Further, in the optical disk apparatus according to claim 11 of the present invention, the signal correction means is configured to detect the signal from the focus position changing means for a predetermined time after the signal from the switching timing generating means transitions from the reproduction state to the pre-recording state. Since the amount of change is multiplied by a predetermined amount, it is possible to reduce the time required for setting the focus control target position change with a simple configuration.

  Further, in the optical disc apparatus according to claim 12 of the present invention, the lens position detecting means is a condensing lens according to the signal of the focus error detecting means when the signal from the switching timing generating means transitions from the reproduction state to the pre-recording state. Is output to the signal correction means, and the signal correction means corrects the signal in accordance with the fluctuation amount of the condenser lens from the lens position detection means, so that it is possible to increase the time that can be shortened for settling of the focus control target position change. it can.

  Further, in the optical disc apparatus according to claim 13 of the present invention, the lens position detecting means collects light according to the signal of the focus error detecting means when the signal from the switching timing generating means transits from the pre-recording state to the recording state. The lens fluctuation amount is output to the signal correction means, and the signal correction means corrects the signal according to the fluctuation amount of the condenser lens from the lens position detection means, so that the time that can be shortened for the stabilization of the focus control target position change is increased. Can do.

  Furthermore, in the optical disk apparatus according to claim 14 of the present invention, when the difference between the reproduction focus control target position held by the focus position changing means and the focus control target position before recording is a predetermined value or more, the recording / reproduction double speed is limited. Since the double speed limiting means is provided, it is possible to prevent a reproduction error caused by changing the focus control target position immediately before recording.

  Furthermore, in the optical disc apparatus according to claim 15 of the present invention, when the difference between the focus control target position for reproduction held by the focus position changing means and the focus control target position before recording is greater than or equal to a predetermined value, the recording and reproduction operations are performed. If the difference between the playback focus control target position held by the focus position changing means and the focus control target position before recording is smaller than a predetermined value, the search operation is performed only during recording to playback. Since the recording / reproducing operation changing means for entering the operation state is provided, it is possible to prevent a reproduction error caused by changing the focus control target position immediately before recording.

  Further, in the optical disc apparatus according to claim 16 of the present invention, when the difference between the focus control target position for reproduction held by the focus position changing means and the focus control target position before recording is equal to or larger than a predetermined value, only during the period from recording to reproduction. A search operation is entered, and no recording, playback, or search is performed between playback and recording. The difference between the focus control target position for playback held by the focus position changing means and the focus control target position before recording is smaller than a predetermined value. In this case, there is provided a recording / playback operation changing means that enters a search operation only during recording and playback and is in an operation state in which continuous operation is performed from playback to recording, so that a playback error caused by changing the focus control target position immediately before recording is provided. Can be prevented.

  Furthermore, in the optical disc apparatus according to claim 17 of the present invention, the focus position changing means changes the focus control target position before recording according to the average value of the light beam emission power at the time of recording. It is possible to reduce a pre-measurement error of the focus control target position shift corresponding to the changing chromatic aberration.

  Furthermore, in the optical disk apparatus according to the eighteenth aspect of the present invention, the lens position detection means obtains the signal from the focus error detection means once at the change timing of the signal from the switching timing generation means. It is possible to measure the focus control target position deviation.

  Furthermore, in the optical disc apparatus according to claim 19 of the present invention, the lens position detecting means obtains the signal from the focus error detecting means by integrating for a predetermined time from the change timing of the signal from the switching timing generating means. The measurement accuracy of the focus control target position deviation can be improved.

  Furthermore, in the optical disk apparatus according to claim 20 of the present invention, the predetermined time for the integration of the lens position detection means is the time until the signal from the focus error detection means is settled. The measurement accuracy can be improved.

The figure which shows the block configuration in Embodiment 1. In Embodiment 1, (a) a diagram illustrating an example of a signal output from the switching timing generation unit, (b) a diagram illustrating an example of a position change of the condenser lens, and (c) a signal output from the FE generation unit The figure which shows an example, (d) The figure which shows an example of the signal output from a transient response detection part, (e) The figure which shows an example of the signal output from an Fc position instruction | indication part In Embodiment 1, (a) a diagram illustrating an example of a signal output from the switching timing generation unit, (b) a diagram illustrating an example of a signal output from the Fc position instruction unit, and (c) from a spherical aberration instruction unit The figure which shows an example of the signal output The figure which shows the block configuration in Embodiment 2. In the second embodiment, (a) a diagram illustrating an example of a signal output from the switching timing generation unit, (b) a diagram illustrating an example of a signal output from the Fc position indicating unit, and (c) a case where the transient response is small The figure which shows an example of the signal output from an FE production | generation part, (d) The figure which shows an example of the signal output from an FE production | generation part when there are many transient responses FIG. 9 shows a block configuration in Embodiment 3. In Embodiment 3, (a) a diagram showing an example of a change in the operating state of the optical disc apparatus when performing normal recording / reproduction, and (b) a diagram showing an example of a change in the operating state of the optical disc device when performing seamless reproduction / recording (C) The figure which shows an example of the operation state change of the optical disk apparatus at the time of performing seamless reproduction | regeneration recording with a gap The figure which shows the block structure in the prior art In the prior art, (a) a diagram showing an example of a change in the operating state of the optical disc apparatus, (b) a diagram showing an example of a signal output from the switching timing generator, and (c) an example of a change in position of the condenser lens. (D) The figure which shows an example of the signal output from Fc position instruction | indication part

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The operation of the optical disk apparatus according to the first embodiment will be described with reference to FIGS. 1, 2, and 3. FIG. FIG. 1 shows a block configuration. FIG. 2 a shows an example of a signal output from the switching timing generation unit 30. FIG. 2 b shows an example of a change in the position of the condenser lens 13. An example of a signal output from the FE generation unit 20 is shown in FIG. FIG. 2d shows an example of a signal output from the transient response detector 31. FIG. 2 e shows an example of a signal output from the Fc position instruction unit 34.

  In FIG. 1, the focus error detection means is a light amount detection unit 17 and an FE generation unit 20. The focus control means is the Fc filter 21. The switching timing generation means is the switching timing generation unit 30. The lens position detection means is a transient response detection unit 31. The focus position changing means is an Fc position instruction unit 34, a recording Fc position generation unit 32, and a pre-recording Fc position generation unit 33. The servo parameter changing means is a spherical aberration generator 16 and a spherical aberration indicator 40.

  In FIG. 1, the same components as those in FIG. The FE generation unit 20 uses the signal of the light amount detection unit 17 to respond to an error signal indicating the convergence state of the light beam on the information surface of the optical disc 1, that is, according to the positional deviation of the focal point of the light beam with respect to the information surface of the optical disc 1. The FE signal is calculated and sent to the Fc filter 21 and the transient response detector 31. When recording on the optical disc 1, the switching timing generation unit 30 defines a pre-recording state from a predetermined time before the start of recording to the start of recording, and detects a transient response for a signal indicating a reproduction state, a pre-recording state, or a recording state To the unit 31, the Fc position indicating unit 34, and the spherical aberration indicating unit 40. The transient response detection unit 31 measures the FE signal change amount when the signal from the switching timing generation unit 30 transits from the pre-recording state to the recording state, and sends it to the pre-recording Fc position generation unit 33. The pre-recording Fc position generation unit 33 multiplies the signal from the transient response detection unit 31 by a predetermined gain and adds it to the current pre-recording Fc position, corrects the detected shift of the focus control target position, and performs the Fc position instruction unit 34. Send to. When the signal from the switching timing generation unit 30 is in the reproduction state or in the recording state, the spherical aberration instruction unit 40 indicates the normal spherical aberration position that is contained therein, and the signal from the switching timing generation unit 30 is in the pre-recording state. Then, the pre-recording spherical aberration position inside is sent to the spherical aberration generator 16. The spherical aberration generator 16 gives a spherical aberration to the light beam according to the spherical aberration position from the spherical aberration indicator 40.

  As shown in FIG. 2b, when the amount of advance movement with respect to the condenser lens 13 when the signal from the switching timing generation unit 30 transitions from the reproduction state to the pre-recording state is insufficient, the switching timing generation unit 30 When the above signal shifts from the pre-recording state to the recording state, a transient response remains at the position of the condenser lens 13. Therefore, as shown in FIG. 2c, a transient response is observed in the FE signal when the signal from the switching timing generation unit 30 transitions from the pre-recording state to the recording state.

  As shown in FIG. 2d, the transient response detection unit 31 acquires and latches the change in the FE signal when the signal from the switching timing generation unit 30 transitions from the pre-recording state to the recording state. The pre-recording Fc position generation unit 33 increases the pre-recording Fc position if the signal from the transient response detection unit 31 is negative, and decreases the pre-recording Fc position if the signal from the transient response detection unit 31 is positive. Let

  While the signal from the switching timing generation unit 30 indicates the pre-recording state, the focus state deteriorates due to the change in the Fc position. The optimum amount of spherical aberration for the light beam varies depending on the focus state. Therefore, while the signal from the switching timing generation unit 30 indicates the pre-recording state, the spherical aberration instruction is set so that the spherical aberration generated by the spherical aberration generation unit 16 becomes an optimum amount according to the changed focus state. Unit 40 changes the signal.

  Thus, by measuring the FE signal and controlling the amount of change in the Fc position performed before recording, it is possible to reduce the transient response of the focus control when entering the recording. Further, by generating a spherical aberration amount corresponding to the change in the Fc position performed before recording, it is possible to reduce the deterioration of the reproduction state immediately before recording.

  In the first embodiment, the reproduction characteristic immediately before recording is improved by changing the amount of spherical aberration, but the reproduction characteristic immediately before recording is changed by changing the gain or offset of tracking control or the detection offset of the circuit system. May be improved. In the first embodiment, the FE signal at the timing of actually entering recording is measured, but the FE signal may be integrated and measured for a predetermined time from the timing of actually entering recording. Furthermore, the measurement time at that time may be fixed, or may be measured until it is detected that the FE signal has settled. Further, when it is detected that the FE signal falls within a predetermined range for a predetermined time, it may be determined that the FE signal has settled. In the first embodiment, the pre-recording Fc position is obtained from the FE signal. As an initial value, the average value of the recording power at the time of recording, the wavelength variation characteristic of the semiconductor laser 11, and the wavelength dependence of the condenser lens 13 are used. The pre-recording Fc position may be obtained from the characteristics.

(Embodiment 2)
The operation of the optical disk apparatus according to the second embodiment will be described with reference to FIGS. FIG. 4 shows a block configuration. FIG. 5 a shows an example of a signal output from the switching timing generation unit 50. FIG. 5 b shows an example of a signal output from the Fc position instruction unit 34. FIG. 5c shows an example of a signal output from the FE generator 20 when the transient response is small. FIG. 5d shows an example of a signal output from the FE generator 20 when there are many transient responses.

  In FIG. 1, the focus error detection means is a light amount detection unit 17 and an FE generation unit 20. The focus control means is the Fc filter 21. The switching timing generation means is a switching timing generation unit 50. The lens position detection means is the transient response detector 31 and the transient response detector 52. The focus position changing means is an Fc position instruction unit 34, a recording Fc position generation unit 32, and a pre-recording Fc position generation unit 33. The timing changing means is a settling time detector 51. The signal correction means is a signal correction unit 53.

  In FIG. 4, the same components as those in FIG. 8 which is the background art and those in FIG. The FE generation unit 20 uses the signal of the light amount detection unit 17 to respond to an error signal indicating the convergence state of the light beam on the information surface of the optical disc 1, that is, according to the positional deviation of the focal point of the light beam with respect to the information surface of the optical disc 1. The FE signal is calculated and sent to the Fc filter 21, the transient response detector 31, the settling time detector 51, and the transient response detector 52. The settling time detection unit 51 uses the timing at which the signal from the switching timing generation unit 50 transitions from the reproduction state to the pre-recording state as a reference until the absolute value of the differentiation of the FE signal becomes a predetermined value or less for a predetermined time. The time is measured and sent to the switching timing generation unit 50. When recording on the optical disc 1, the switching timing generator 50 defines a pre-recording state from a predetermined time before the start of recording to the start of recording as a pre-recording state, and detects a transient response for a signal indicating a reproduction state, a pre-recording state, or a recording state Unit 31, Fc position indicating unit 34, signal correcting unit 53, settling time detecting unit 51, and transient response detecting unit 52. Further, the switching timing generation unit 50 sets the measurement time from the settling time detection unit 51 as the time width of the state before recording. The transient response detector 52 integrates and measures the FE signal when the signal from the switching timing generator 50 transitions from the reproduction state to the pre-recording state for a predetermined time and sends the signal to the signal correction unit 53. When the signal from the switching timing generation unit 50 is in a reproduction state, the Fc position instruction unit 34 indicates an internal reproduction Fc position, and when the signal from the switching timing generation unit 50 is in a pre-recording state, the pre-recording Fc position generation unit 33. When the signal from the switching timing generation unit 50 is in the recording state, the recording Fc position from the recording Fc position generation unit 32 is sent to the signal correction unit 53. The signal correction unit 53 multiplies the change in the signal from the Fc position instruction unit 34 by a predetermined amount for a predetermined time after the signal from the switching timing generation unit 50 transitions from the reproduction state to the pre-recording state. Send to. Further, the signal correction unit 53 changes the magnification of the predetermined magnification in accordance with the signal from the transient response detection unit 52.

  While the Fc position is changed in a simple step shape as shown in FIG. 9d in the background art, the transient response of the focus control is changed by changing it in a two-step step shape as shown in FIG. 5b.

  When the transient response of the focus control is slow because the condenser lens 13 is heavy, the FE signal has a waveform as shown in FIG. 5c. The transient response detection unit 52 measures the hatched area by integrating for a predetermined time. In this case, since the measurement result is negative, the signal correction unit 53 increases the magnification by a predetermined factor.

  When the transient response of the focus control is fast because the condenser lens 13 is light, the FE signal has a waveform as shown in FIG. 5d. The transient response detection unit 52 measures the hatched area by integrating for a predetermined time. In this case, since the measurement result is positive, the signal correction unit 53 reduces the magnification by a predetermined factor.

  The transient response of the focus control takes time to settle whether it is too slow or too fast. As described above, the time required for settling can be shortened by the signal correction unit 53 performing optimal correction. The settling time detection unit 51 determines that the focus control has settled when the absolute value of the differentiation of the FE signal becomes equal to or less than a predetermined value for a predetermined time, and the signal from the switching timing generation unit 50 changes from the reproduction state to the pre-recording state. Delay the transition timing to shorten the time when the focus state deteriorates.

  In this way, by correcting the change waveform of the offset amount given to the FE generation unit 20 by the signal correction unit 53, the settling time of the focus control transient response is shortened, and from the switching timing generation unit 50 by shortening the settling time. By delaying the timing of the transition of the signal from the reproduction state to the pre-recording state, the time during which the focus state is deteriorated can be shortened, and the deterioration of reproduction characteristics can be reduced.

  In the second embodiment, the transient response time of the focus control is shortened by correcting the signal from the Fc position indicating unit 34. However, the gain of the Fc filter 21 is temporarily increased to reduce the transient response time of the focus control. It may be shortened. Furthermore, the timing for returning the gain of the Fc filter 21 at that time may be a timing for detecting that the FE signal has settled. In the second embodiment, the transient response detection unit 52 measures the transient response when the signal from the switching timing generation unit 50 transitions from the reproduction state to the pre-recording state, but the signal from the switching timing generation unit 50 is The transient response detector 52 may measure a transient response when transitioning from the pre-recording state to the recording state. In the second embodiment, the pre-recording Fc position is obtained from the FE signal. As an initial value, the average value of the recording power at the time of recording, the wavelength variation characteristic of the semiconductor laser 11, and the wavelength dependence of the condenser lens 13 are used. The pre-recording Fc position may be obtained from the characteristics. In the second embodiment, when the absolute value of the differentiation of the FE signal becomes equal to or less than a predetermined value for a predetermined time, it is determined that the FE signal has settled, but the FE signal falls within a predetermined range for the predetermined time. May be determined that the FE signal has settled. In the second embodiment, the offset amount at the time of transient response applied to the FE signal is changed. However, the offset time at the time of transient response added to the FE signal may be changed. Further, in the second embodiment, the transient response of the focus control is reduced by changing the offset amount added to the FE signal by two steps, but it may be a change divided into two or more steps.

(Embodiment 3)
The operation of the optical disk apparatus according to the third embodiment will be described with reference to FIG. FIG. 6 shows a block configuration.

  In FIG. 6, the focus error detection means is a light amount detection unit 17 and an FE generation unit 20. The focus control means is the Fc filter 21. The switching timing generation means is the switching timing generation unit 30. The lens position detection means is a transient response detection unit 31. The focus position changing means is an Fc position instruction unit 34, a recording Fc position generation unit 32, and a pre-recording Fc position generation unit 33. The double speed limiting means is a double speed instruction unit 60.

  In FIG. 6, the same components as those in FIG. 8 which is the background art and those in FIG. The pre-recording Fc position generation unit 33 multiplies the signal from the transient response detection unit 31 by a predetermined gain and adds it to the current pre-recording Fc position, corrects the detected shift of the focus control target position, and performs the Fc position instruction unit 34. And sent to the double speed instruction unit 60. The double speed instruction unit 60 lowers the upper limit of the double speed at which recording / reproduction is performed on the optical disc 1 when the signal from the pre-recording Fc position generation unit 33 is large. Further, the double speed instruction unit 60 outputs a drive signal to the motor 61 according to the double speed state. The motor 61 rotates the optical disc 1 based on the drive signal from the double speed instruction unit 60.

  Just before recording, the focus state deteriorates and the reproduction characteristics deteriorate. This problem increases depending on the amount of Fc position that changes when the signal from the switching timing generation unit 30 changes from the reproduction state to the recording state, that is, the amount of signal from the pre-recording Fc position generation unit 33. When the signal from the pre-recording Fc position generation unit 33 is equal to or greater than a predetermined value, the double speed instruction unit 60 limits the upper limit of the double speed at which recording / reproduction is performed. The motor 61 is rotated at a low speed.

  In this way, by limiting the double speed, garbled data when the Fc position change is large before recording can be suppressed.

  In the third embodiment, the influence of the Fc position change performed before recording is reduced by restricting the double speed. However, the reproducing operation and the recording operation may not be performed between recordings. This will be specifically described with reference to FIG. FIG. 7a shows an example of a change in the operating state of the optical disc apparatus during normal recording / reproduction. FIG. 7b shows an example of a change in the operating state of the optical disc apparatus in seamless playback recording. FIG. 7c shows an example of a change in the operation state of the optical disc apparatus in the seamless reproduction recording with a gap. When the data buffer RAM used for recording / reproduction is sufficient, as shown in FIG. 7a, the search operation is always inserted before the recording operation and the reproduction operation. The rate of time during which search operations are performed increases and the transfer rate deteriorates. Therefore, as shown in FIG. 7b, seamless playback recording is performed in which the search operation between the playback operation and the recording operation is reduced and the operation is continued. When the signal from the pre-recording Fc position generation unit 33 is equal to or greater than a predetermined value, the normal operation as shown in FIG. 7a is performed instead of the seamless reproduction recording, so that the transfer rate is lowered but the reproduction immediately before the recording is stabilized. Can be made. Further, when the transfer rate is drastically reduced in normal recording, as shown in FIG. 7c, the search operation between the reproduction operation and the recording operation is reduced, but a predetermined interval such as one sector is defined as an interval in which neither reproduction operation nor recording operation is performed. By performing seamless playback recording with gaps, the transfer rate drop can be reduced.

  The present invention provides an optical disc apparatus that changes a focus control target position (hereinafter referred to as an Fc position) before recording when recording or reproduction is performed on a disc-shaped information carrier (hereinafter referred to as an optical disc) capable of recording. Is available.

DESCRIPTION OF SYMBOLS 1 Optical disk 10 Optical head 11 Semiconductor laser 12 Beam splitter 13 Condensing lens 14 Fc actuator 15 Tk actuator 16 Spherical aberration generation part 17 Light quantity detection part 20 FE production | generation part 21 Fc filter 30 Switching timing generation part 31 Transient response detection part 32 Recording Fc Position generation section 33 Pre-recording Fc position generation section 34 Fc position instruction section 40 Spherical aberration instruction section 50 Switching timing generation section 51 Settling time detection section 52 Transient response detection section 53 Signal correction section 60 Double speed instruction section 61 Motor

Claims (20)

A focus error detecting means for detecting a signal corresponding to the positional deviation of the focal point of the light beam with respect to the information surface or surface of the information carrier, and the focus of the light beam changes the information surface of the information carrier according to the signal of the focus error detecting means; Focus control means for changing the convergence state of the light beam so as to follow, and switching timing generation for outputting three states of a reproduction state, a pre-recording state, and a recording state in accordance with the operation of recording and reproducing the information carrier And a lens position detecting means for outputting a fluctuation amount of the condenser lens according to a signal of the focus error detecting means when a signal from the switching timing generating means transits from a pre-recording state to a recording state, and information The focus control target position in the three states of the reproduction state, the pre-recording state, and the recording state is maintained according to the operation of performing the recording / reproduction on the carrier, and the switching Focus position changing means for outputting to the focus error detecting means a signal for changing the focus control target position in accordance with a signal from the imming generating means, the focus position changing means being a condensing lens from the lens position detecting means An optical disc apparatus characterized by changing a focus control target position before recording in accordance with a variation amount of the optical disc. 2. The optical disk apparatus according to claim 1, further comprising: a servo parameter changing unit that changes a servo parameter in a section in which a signal from the switching timing generating unit indicates a pre-recording state. 2. A track error detecting means for detecting a signal corresponding to a positional deviation between the light beam and a track on the information carrier, wherein the servo parameter changing means changes a detection gain of the track error detecting means. 2. The optical disc device according to 2. 3. A track error detecting means for detecting a signal corresponding to a positional deviation between the light beam and a track on the information carrier, wherein the servo parameter changing means changes the offset of the track error detecting means. The optical disk device described. 3. The optical disk apparatus according to claim 2, wherein the servo parameter changing means changes the application amount of the servo signal detection circuit offset. 3. An optical disk apparatus according to claim 2, wherein the servo parameter changing means changes the amount of spherical aberration given to the light beam. The switching timing generation means transitions from the reproduction state to the pre-recording state according to the transient response settling time of the signal from the focus error detection means when the signal from the switching timing generation means transitions from the reproduction state to the pre-recording state. 2. The optical disk apparatus according to claim 1, further comprising timing changing means for changing timing. 8. The optical disc apparatus according to claim 7, wherein the focus control means increases the focus control gain when the signal from the switching timing generation means transitions from the reproduction state to the pre-recording state. The focus control unit returns the focus control gain when the signal from the focus error detection unit settles after the signal from the switching timing generation unit transitions from the reproduction state to the pre-recording state to increase the focus control gain. The optical disk device according to claim 8. And a signal correction unit that corrects a transient response waveform, such as overshooting the signal from the focus position changing unit when the signal from the switching timing generation unit transitions from the reproduction state to the pre-recording state. Item 8. The optical disk device according to Item 7. 11. The signal correcting means multiplies the change of the signal from the focus position changing means by a predetermined time for a predetermined time after the signal from the switching timing generating means transits from the reproduction state to the pre-recording state. The optical disk device described. The lens position detection means outputs the fluctuation amount of the condenser lens to the signal correction means according to the signal of the focus error detection means when the signal from the switching timing generation means transits from the reproduction state to the pre-recording state, and the signal correction 11. The optical disc apparatus according to claim 10, wherein the means corrects the signal in accordance with a fluctuation amount of the condenser lens from the lens position detecting means. The lens position detection means outputs the fluctuation amount of the condenser lens to the signal correction means according to the signal of the focus error detection means when the signal from the switching timing generation means transits from the pre-recording state to the recording state, and the signal 11. The optical disk apparatus according to claim 10, wherein the correcting means corrects the signal in accordance with a fluctuation amount of the condenser lens from the lens position detecting means. 2. A double speed limiting unit for limiting a recording / reproducing double speed when a difference between a focus control target position for reproduction held by the focus position changing unit and a focus control target position before recording is a predetermined value or more. 1. The optical disc device according to 1. When the difference between the focus control target position for reproduction held by the focus position changing means and the focus control target position before recording is greater than or equal to a predetermined value, a search operation is performed between the recording and reproduction operations. A recording / reproducing operation changing unit that enters an operation state in which a search operation is performed only during a period from recording to reproduction when the difference between the focus control target position for reproduction held by the changing unit and the focus control target position before recording is smaller than a predetermined value; The optical disk apparatus according to claim 1, wherein When the difference between the focus control target position for playback held by the focus position changing means and the focus control target position before recording is greater than or equal to a predetermined value, a search operation is performed only during recording and playback, and recording is also played back during playback. When the difference between the focus control target position for reproduction held by the focus position changing means and the focus control target position before recording is smaller than a predetermined value, the search operation is performed only during recording and reproduction. 2. The optical disk apparatus according to claim 1, further comprising a recording / reproducing operation changing unit that is in an operation state in which continuous operation is performed from reproduction to recording. 2. The optical disk apparatus according to claim 1, wherein the focus position changing means changes the focus control target position before recording according to the average value of the light beam emission power at the time of recording. 2. The optical disk apparatus according to claim 1, wherein the lens position detecting means acquires the signal from the focus error detecting means once at the change timing of the signal from the switching timing generating means. 2. The optical disk apparatus according to claim 1, wherein the lens position detecting means acquires the signal from the focus error detecting means by integrating for a predetermined time from the change timing of the signal from the switching timing generating means. 20. The optical disk apparatus according to claim 19, wherein the predetermined time for integration by the lens position detecting means is a time until a signal from the focus error detecting means is settled.

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