JP3758347B2 - Focusing device in optical disk device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a focusing device and a tracking device in an optical disk device using a multilayer film medium.
[0002]
[Prior art]
  The focusing servo keeps the relative distance between the objective lens and the disk signal surface constant with respect to the surface vibration of the disk so that the disk signal surface is located within the range of the beam waist of the laser, the so-called depth of focus (about ± 1 μm). Control the objective lens. The focusing servo detects a focusing error signal from the state of reflected light from the disk, and drives the objective lens. FIG. 21 shows a specific example of a conventional focusing servo circuit. In the figure, 88 is a pickup light detection diode, 89 is a current-voltage conversion circuit, 90 is a subtraction circuit, 91 is a phase compensation circuit, 92 is a switch, 93 is a drive circuit / pickup UP / DOWN circuit, and 94 is a pickup UP / DOWN circuit. A DOWN signal, 95 is a focus actuator, and 96 is an automatic focus detection circuit. The four diodes 88 are divided into four photodetectors, and two sets of diagonal detectors are respectively input to a subtracting circuit to generate a focusing error signal. The focusing error signal drives the focus actuator 95 through the phase compensation circuit 91 of the servo loop, the switch circuit 92 of the loop, and the drive circuit. Although the relative position of the objective lens and the disc must be kept within ± 1 μm, it is impossible to mount the disc on the CD player with high accuracy within ± 1 μm. Therefore, it is necessary to lift the objective lens at a position away from the disk and drive the objective lens within the servo control range, that is, until a focusing error signal is obtained. The pickup UP / DOWN signal 94 is an objective lens drive signal for this purpose. The switch is a switch for closing the servo loop with an automatic focus detection signal (FOK signal) when the objective lens enters a servo range, that is, enters an S-shaped focusing error signal negative feedback region.
[0003]
  FIG. 22 is an overall configuration diagram of a recording / reproducing and reproducing apparatus using a conventional optical disc. In the figure, 66 is an optical disk (multilayer film disk), 67 is a disk motor, 68 is a disk motor servo, 69 is a laser diode, 70 is an objective lens, 71 is a focusing actuator, 72 is a tracking actuator, 73 is a photodetector, 74. Is a pickup feed mechanism, 75 is an auto laser power control circuit, 76 is a focusing servo circuit, 77 is a tracking servo circuit, and 78 is a pickup feed servo circuit.
[0004]
  The disc in the standard has a thickness of 1.2 mm by laminating substrates with a thickness of 0.6 mm. In the case of a single-sided disc, a 0.6 mm thick substrate to which information is transferred at the time of molding is bonded with the information recording surface facing each other. In addition, by forming a translucent layer on one information recording surface of the disc and forming a normal reflective layer on the other information recording surface, the information on both recording layers is reversed from the substrate side on which the translucent layer is formed. Can be read without having to. In this case, the thickness of the adhesive layer between the first layer and the second layer is 30 to 40 μm, and when one information recording layer is read, the other information recording layer is defocused by about 30 to 40 μm. Thus, the reflected light from the other information recording layer hardly changes. That is, the interlayer stroke has a very small value.
[0005]
  However, when reading the first layer and reading the second layer, the thickness of the substrate is substantially different by 30 to 40 μm. This thickness error causes spherical aberration of the optical system. Therefore, the thickness of the substrate on which the first layer is formed is made thinner than 0.6 mm by about half the thickness of the adhesive layer so that the error is distributed to both layers. By doing so, the thickness of the substrate up to the first layer is about 20 μm thinner, and the thickness of the substrate up to the second layer is about 20 μm thicker. When reading either layer, the same substrate thickness error occurs and slight aberrations are caused. Therefore, the recording density is reduced by 10%, the storage capacity per layer is 4.25 GB, and both layers are combined. It was set to 8.5 GB. FIG. 23 shows the structure of a conventional optical disc. When performing a normal track jump, an intermediate position between tracks can be detected. By switching the kick pulse and brake pulse at that position, the eccentricity of the disk, the direction of travel from the current position to the target position is applied to the servo loop, and the driving force in the reverse direction from the half position to the target position The jump is performed with the servo loop closed until a brake pulse is applied. In particular, in the case of track jump, there is a problem that the inertia force is applied to the actuator due to the disc eccentricity, and the jump pull-in failure occurs due to the influence of the inertia force that applies the kick pulse and the brake pulse having a fixed pulse length. . However, if the middle point between tracks is detected and the pulses are switched here, the pulse width is varied according to the magnitude of inertia because the time to reach the middle point is different even if a pulse of the same voltage is applied. , Offset the effects of eccentricity.
[0006]
[Problems to be solved by the invention]
  Conventionally, the surface shake of an optical disk obtained from a photodetectorFocus error corresponding toFocus control is performed based on the signal, and the objective lens is moved in the vertical direction by using a focus actuator to follow the surface vibration of the disk and perform focusing. However, when a focus jump is performed from the first layer to the second layer or from the second layer to the first layer in a recording / reproducing or reproducing apparatus using a multilayer disk, a reference signal cannot be obtained. There was a problem that it could not be performed stably.
[0007]
  The present invention has been made in order to solve the above-described problems.Focus error signal corresponding toAn object of the present invention is to obtain a focusing device in an optical disc apparatus capable of stably performing a focus jump by detecting or estimating the angle and varying the height of the kick pulse based on this signal to obtain an optimum kick pulse. .
[0008]
[Means for Solving the Problems]
  In the focusing device in the optical disk apparatus according to the present invention, in the optical disk apparatus for recording / reproducing a multilayer optical disk having a plurality of information recording / reproducing surfaces, a light detection means and a focus error generation for generating a focus error signal from the light detection means Means, focus control means corresponding to optical disc surface shake from the focus error signal, focus jump generating means for generating a focus pulse and a brake pulse for performing a focus jump from the current layer to the next layer in response to the focus error signal, Switching between the focus search pull-in means based on the focus error signal, the output from the focus jump generating means and the output from the focus control means, or the signal from the focus search pull-in means. And a focus driving means that is driven by an output from the switching means, the focus jump generating means detecting an escape speed from the current layer based on the focus error signal, and the escape speed detecting means Kick pulse height determining means for determining the height of the kick pulse and the width of the kick pulse from the output from the kick pulse, kick pulse generating means for generating the kick pulse by the output from the kick pulse height determining means, and the focus Error signalReaches a predetermined signal level determined based on a pre-stored maximum amplitudeBrake pulse generating means for generating a brake pulse of a predetermined height and width;An upper limit value and a lower limit value of a signal level of a predetermined focus error signal are determined based on the maximum amplitude of the focus error signal, and a signal level of the focus error signal after a predetermined time has elapsed since the occurrence of the brake pulse. When the signal level is higher than the upper limitOvershoot of the focus error signalWhen the focus error signal is lower than the lower limit value of the predetermined signal level,Overshoot and undershoot detection means for detecting undershoot, and overshoot and undershoot detection meansIf the detected result indicates an overshoot, an auxiliary pulse for further braking is generated, and if the detected result indicates an undershoot, an auxiliary pulse having a polarity opposite to that of the brake pulse is generated.It comprises auxiliary pulse generating means.
[0009]
  In the present invention, when a focus jump is performed from the current layer to the next layer, the overshoot and undershoot of the focus error signal are detected by the overshoot / undershoot detection means, and an assist is made based on the overshoot and undershoot values. An auxiliary pulse is generated by using a pulse generating means, and an arbitrary auxiliary pulse is applied to the brake pulse when the brake is too strong at the end of the focus jump and when the brake is too weak.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
Embodiment 1 FIG.
  FIG. 24 shows a focus error signal at the time of a focus jump when a multilayer disk is used. 79 is a multilayer disk, 80 is a second layer information recording surface, 81 is a first layer information recording surface, and 82 is An optical pickup focused on the first layer, 83 an optical pickup focused on the second layer, 84 a focus error signal waveform when performing a focus jump from the current layer to the next layer, and 85 in the current layer In-focus, 86 is in-focus in the next layer, and 87 is a focus error signal from the in-focus in the current layer to the in-focus of the next layer. In the figure, for example, when a focus jump is performed from the first layer to the second layer, first, the focus error signal and the in-focus point 85 of the first layer (current layer) can be obtained as shown by a waveform 84. Next, in order to enter the second layer (next layer), the focus error signal and the focal point 86 in the second layer can be obtained. This indicates that a focus jump was performed in order to focus on the second layer with the optical pickup 83 from the state in which the optical pickup 82 focused on the first layer as shown in the left diagram of FIG. Here, the pickups 82 and 83 are the same optical pickups except that the focused layers are different. 87 from the focus of the current classNext layerThe focus error signals up to the in-focus point are shown below and have the same meaning as the focus error signals in FIGS. 3, 4, 6, 7, 14, and 15. (Focus error signals from the focal point of the first layer to the focal point of the second layer and from the focal point of the second layer to the focal point of the first layer.)
  FIG. 1 is a block diagram of a focus servo circuit of a recording / reproducing and reproducing apparatus using a multilayer disk according to Embodiment 1 of the present invention. In the figure, 1 is a multilayer optical disk, 2 is a disk motor, 3 is an optical pickup, 4 is a focus error amplifier, 5 is a focus loop low-pass compensation filter, 6 is a focus loop phase compensation filter, 7 is a focus search pull-in circuit, and 8 is A focus jump circuit, 9 is a changeover switch, 10 is a focus actuator driver, and 11 is a focus actuator.
[0011]
  In the figure, first, the surface shake of the optical disc is passed from the optical pickup 3 through the focus error amplifier 4.Focus error corresponding toA signal is output and input to the focus loop low-pass compensation filter 5, the focus search pull-in circuit 7, and the focus jump circuit 8, respectively. The output of the focus loop low-frequency compensation filter 5 is added to the output of the focus jump circuit 8 via the focus loop phase compensation filter 6 and connected to the changeover switch 9. The output of the focus search pull-in circuit 7 is connected to the changeover switch 9. Either the added output or the output of the focus search pull-in circuit 7 is configured to drive the focus actuator 11 via the focus actuator driver 10. For example, if focus control is applied to the first layer of the optical disc, the disc surface deflectionFocus error signal corresponding toDetect or estimateThe faithThe focus jump signal is obtained by determining the kick pulse start based on the signal. In this case, the kick pulse and the brake pulse are determined based on the residual error signal detected as the focus error signal, and the focus jump when the actuator becomes zero acceleration in the focus direction or the reference kick pulse when the acceleration is zero. This is performed by adding and subtracting the correction amount corresponding to the actuator acceleration (inertia amount) estimated from the residual error signal to the width and the brake pulse width or height, and applying the kick pulse and the brake pulse. Here, the kick pulse variable circuit 14 outputs the optimum kick pulse to the mounted optical disk by varying the height of the kick pulse based on the residual error signal, and forcibly obtains the focus jump signal. The focus can be adjusted on the second layer. When a focusing device including a kick pulse variable circuit for obtaining the focus signal is used, a focus jump can be stably performed in a recording / reproducing or reproducing device using a multilayer disk.
[0012]
  FIG. 2 is a block diagram of the focus jump circuit according to the first embodiment of the present invention. In the figure, 12 is an escape speed detection circuit from the current layer, 13 is a kick pulse height determination circuit, 14 is a kick pulse generation circuit, and 15 is A jump time speed detection circuit to the next layer, 16 is a brake pulse height determination circuit, 17 is a brake pulse generation circuit, and 18 is an adder. In the figure, the focus error signal obtained from the optical pickup is input to the escape speed detection circuit 12 from the current layer and the jump-in detection circuit 15 to the next layer, respectively.
  When performing a focus jump in an optical disk reproducing apparatus using a multilayer disk, it is extremely difficult to perform a focus jump stably if a fixed pulse is used. Therefore, the current focus control is performed by the escape speed detection circuit 12 from the current layer. From the layerProlapseThe outgoing speed is detected, and the kick pulse height determination circuit 13 determines the height of the kick pulse that can stably perform a focus jump to the next layer. Based on this determination, a kick pulse can be generated by the kick pulse generation circuit 14. Further, the next layer jump detection circuit 15 moves to the next layer.FlyingThe jumping time or jumping speed is detected, and the brake pulse height determining circuit 16 determines the height of the brake pulse. Based on this determination, a brake pulse is generated by the brake pulse generation circuit 17 and added by the kick pulse and the adder 18 to obtain a kick pulse and a brake pulse necessary for stable focus jump in the multilayer disk. . FIG. 3 shows waveforms of a focus error signal, a kick pulse, and a brake pulse when performing a focus jump from the first layer to the second layer in a multilayer disk. In the figure, 19 is a focus error signal, a is an arbitrary kick pulse generation value, a 'is an arbitrary threshold value, b is an arbitrary threshold value, 20 is a kick pulse brake pulse waveform when performing a focus jump, and 21 is a jump. Pulse and kick pulse, 22 is a brake pulse, c is a variable height value of the kick pulse, and d is a variable height value of the brake pulse. 21 in the figurefillA jump pulse that triggers the focus jump operation, which is a part, is generated, the value from the position of the focus error signal to the position of a ′ is measured, and the height c of the kick pulse generated based on the value c Similarly, it can be seen that the brake pulse is generated at the threshold value b and the height d of the brake pulse is varied. FIG. 4 shows the waveforms of the kick pulse and the brake pulse when performing a focus jump from the second layer to the first layer in the multilayer disk, 23 is a focus error signal, 24 is a focus jump. Kick pulse brake pulse waveform when performing, 25 indicates a kick pulse, and 26 indicates a brake pulse. Similarly, the value from the position of e to the position of e ′ in the focus error signal is measured, the height g of the kick pulse generated based on the value is varied, the brake pulse is generated with the threshold value f, It can be seen that the height h of the brake pulse is variable. As a result, when the jumping speed of the light spot from the first layer is increasing, the height of the kick pulse is reduced, and as a result, the jumping speed is controlled to be constant. Further, when the pop-out speed is decreasing, the kick pulse height is increased, and as a result, control is performed so as to keep the pop-out speed constant. Further, when the rush speed to the second layer is increasing, the height of the brake pulse is increased, and as a result, the rush speed is controlled to be constant. Further, when the rush speed is decreasing, the brake pulse height is decreased, and as a result, control is performed so as to keep the rush speed constant.
[0013]
Embodiment 2. FIG.
  FIG. 5 is a block diagram of a focus jump circuit according to the second embodiment of the present invention. In the figure, 12 to 18 are the same as in FIG.
[0014]
  In the figure, the focus error signal obtained from the optical pickup is input to the escape speed detection circuit 12 from the current layer and the jump-in detection circuit 15 to the next layer, respectively.
When performing a focus jump in an optical disk reproducing apparatus using a multilayer disk, it is extremely difficult to perform a focus jump stably if a fixed pulse is used. Therefore, the current focus control is performed by the escape speed detection circuit 12 from the current layer. From the layerProlapseThe exit speed is detected, and the kick pulse height determination circuit 13 determines the height or width of the kick pulse that can stably perform a focus jump to the next layer. Based on this determination, a kick pulse can be generated by the kick pulse generation circuit 14. Further, the next layer jump detection circuit 15 moves to the next layer.FlyingThe jumping time or jumping speed is detected, and the detected result and the output of the kick pulse height determining circuit 13 are used as the brake pulse height determining circuit 16.InInput and determine the height or width of the brake pulse in conjunction with the height or width of the kick pulse. Based on this determination, a brake pulse is generated by the brake pulse generation circuit 17 and added by the kick pulse and the adder 18 to obtain a kick pulse and a brake pulse necessary for stable focus jump in the multilayer disk. .
  FIG. 6 shows waveforms of a focus error signal, a kick pulse, and a brake pulse when performing a focus jump from the first layer to the second layer in the multilayer disk. In the figure, 19 is a focus error signal, 27 is a kick pulse brake pulse waveform when performing a focus jump, 28 is a jump pulse and a kick pulse, 29 is a brake pulse, i is a variable height value of the kick pulse, and j is a brake The variable height value of the pulse, k, indicates the width of the brake pulse determined in relation to the width of the kick pulse. 28 in the figurefillThe jump pulse that triggers the focus jump operation, which is a part, is generated, the value of the focus error signal from the position a to the position a 'is measured, and the height of the kick pulse generated based on the above valueiSimilarly, the brake pulse is generated with the threshold value b, and the height of the brake pulse is changed.jOr the width k of the brake pulse can be varied in relation to the width of the kick pulse. FIG. 7 shows the waveforms of a kick pulse and a brake pulse when performing a focus jump from the second layer to the first layer in the multilayer disk, 23 is a focus error signal, and 30 is a focus jump. A kick pulse brake pulse waveform when performing, 31 indicates a jump pulse and a kick pulse, and 32 indicates a brake pulse. In the figure, the value of the focus error signal from the position e to the position e ′ is measured, the kick pulse height l generated based on the above value is varied, and similarly, the brake pulse is generated with the threshold value f. The height m of the brake pulse can be varied, or the width n of the brake pulse can be varied in proportion to the width of the kick pulse. With this configuration, when the escape speed cannot be detected accurately due to a scratch on the disc, the brake pulse is not linked even if the kick pulse height is abnormal, preventing the focus jump from shifting. be able to.
[0015]
Embodiment 3 FIG.
  FIG. 8 is a block diagram of a focus jump circuit according to Embodiment 3 of the present invention. In the figure, 12 to 18 are the same as those in FIG. Reference numeral 33 denotes an overshoot / undershoot detection circuit, and 34 denotes an auxiliary pulse generation circuit.
[0016]
  In the figure, kick pulses and brake pulses are generated as in the first embodiment, and overshoot and undershoot of the focus error signal are detected by the overshoot / undershoot detection circuit 33, and the values of the overshoot and undershoot are obtained. Based on this, the auxiliary pulse generation circuit 34 is used to generate an auxiliary pulse, and when the brake is too strong at the end of the focus jump and when the brake is too weak, an arbitrary auxiliary pulse is applied to the brake pulse. By applying an auxiliary pulse to the brake pulse, a focus jump from the current layer to the next layer in the multilayer disk can be performed stably and reliably.
[0017]
  The operation of FIG. 8 is specifically shown below. FIG. 9 is a diagram illustrating a focus error and a brake pulse to which an auxiliary pulse is applied when the brake is too strong during a focus jump operation from the first layer to the second layer of an optical disk apparatus using a multilayer disk. is there. In the figure, 35 is a focus error signal, 36 is a brake pulse to which an auxiliary pulse is applied, and femax is the maximum amplitude of the focus error signal. Referring now to FIG. 9, a fixed brake pulse is applied when femax / 4. When the value of the focus error signal 35 when an arbitrary set time T1 has elapsed is 50% or more of femax, a focus jump from the first layer to the second layer is performed by applying an auxiliary pulse as shown in the figure. When the value of the focus error signal 35 is equal to or more than half of the value of femax at the end of the brake, that is, even when the brake is too strong, the focus jump can be performed stably.
[0018]
  FIG. 10 is a diagram showing a focus error signal and a brake pulse to which an auxiliary pulse is applied when the brake is too weak during the focus jump operation from the first layer to the second layer of the optical disc apparatus using the multilayer disc. It is. In the figure, 37 indicates a focus error signal, and 38 indicates a brake pulse to which an auxiliary pulse is applied. Referring now to FIG. 10, a fixed brake pulse is applied when femax / 4. When the value of the focus error signal 37 when the arbitrary set time T1 has elapsed is 50% or less of −femax, the auxiliary pulse is applied as shown in the figure to focus from the first layer to the second layer. In the jump, when the value of the focus error signal 37 is less than half of the value of −femax at the end of the brake, that is, when the brake is too weak, the focus jump can be performed stably.
[0019]
  FIG. 11 shows a focus pulse and a brake pulse to which an auxiliary pulse is applied when the brake is too weak during the focus jump operation from the second layer to the first layer of the optical disc apparatus using the multilayer disc. FIG. In the figure, 39 is a focus error signal, 40 is a brake pulse to which an auxiliary pulse is applied, and femax is the maximum amplitude of the focus error signal. Referring now to FIG. 11, a fixed brake pulse is applied when -femax / 4. When the value of the focus error signal 39 when an arbitrary set time T2 has elapsed is 50% or more of femax, a focus jump from the second layer to the first layer is performed by applying an auxiliary pulse as shown in the figure. When the value of the focus error signal 39 is more than half of the value of femax at the end of braking, that is, even when the brake is too weak, the focus jump can be performed stably.
[0020]
  FIG. 12 is a diagram showing a focus error signal and a brake pulse to which an auxiliary pulse is applied when the brake is too strong during the focus jump operation from the second layer to the first layer of the optical disc apparatus using the multilayer disc. It is. In the figure, 41 indicates a focus error signal, and 42 indicates a brake pulse to which an auxiliary pulse is applied. Referring now to FIG. 12, a fixed brake pulse is applied when -femax / 4. When the value of the focus error signal 41 when the arbitrary set time T2 has elapsed is 50% or less of −femax, the auxiliary pulse is applied as shown in the figure to focus from the second layer to the first layer. In the jump, when the value of the focus error signal 41 is less than half of the value of −femax at the end of the brake, that is, when the brake is too strong, the focus jump can be performed stably.
  Note that the value of the fixed brake pulse and the value of the focus error signal when the arbitrarily set times T1 and T2 have elapsed in this embodiment are merely examples.
[0021]
Embodiment 4 FIG.
  FIG. 13 is a block diagram of a focus jump circuit according to the fourth embodiment of the present invention. In the figure, 12 to 18 are the same as those in FIG. Reference numeral 33 denotes an overshoot / undershoot detection circuit, 34 denotes an auxiliary pulse generation circuit, and 43 denotes a time measurement circuit.
[0022]
  When the auxiliary pulse is determined only from the overshoot and undershoot as described above, the undershoot amount varies depending on the overshoot amount even if the focus servo gain is large. there were. In addition, since these overshoots and undershoots vary depending on the speed of the light spot entering the next layer, it is necessary to consider the factor of this speed of jump. Here, as in the first embodiment, when a kick pulse and a brake pulse are generated and an auxiliary pulse is applied based on overshoot and undershoot values, a focus jump start command signal and a jump time to the next layer A signal from the speed detection circuit 15 is input to the time measurement circuit 43, the time from the end of the kick pulse to the time of occurrence of the brake pulse is measured, and the height of the brake pulse is varied in association with this time. The output of the time measuring circuit 43 is also input to the auxiliary pulse generating circuit 34, and the height of the auxiliary pulse can be similarly varied. In other words, by measuring the time from the end of the kick pulse to the occurrence of the brake pulse, for example, when the above time is short, the jump speed to the next layer is fast, the height of the brake pulse and auxiliary pulse is increased, The focus jump from the current layer to the next layer in the multilayer disk can be performed stably and reliably. In addition, if the above time is long, the dive into the next layer is performed relatively slowly, so the brake pulse and auxiliary pulse height is lowered, and the brake is weak and not overly stiff. In addition, the focus jump from the current layer to the next layer in the multilayer disk can be performed reliably.
[0023]
  FIG. 14 is a view showing waveforms of a focus error signal and a kick pulse brake pulse when a focus jump from the first layer to the second layer in the multilayer disk is performed. In the figure, 44 is the focus error signal, 45 is the waveform of the kick pulse brake pulse, and T3 is the time from the end of the kick pulse to the occurrence of the brake pulse. The focus jump described in the fourth embodiment can be performed by associating the height of the brake pulse and the auxiliary pulse with the length of time T3 in FIG. FIG. 15 is a view showing waveforms of a focus error signal and a kick pulse brake pulse when a focus jump is performed from the second layer to the first layer in the multilayer disk. In the figure, 46 is a focus error signal, 47 is a waveform of a kick pulse brake pulse, and T4 is a time from the end of the kick pulse to the occurrence of the brake pulse. Similarly, the stable and reliable focus jump described in the fourth embodiment is performed with respect to the fluctuation of the focus gain by associating the height of the brake pulse and the auxiliary pulse with the length of time T4 in FIG. Can do.
[0024]
Embodiment 5. FIG.
  FIG. 16 is a block diagram of a focus jump circuit according to the fifth embodiment of the present invention. In the figure, 12 to 18 are the same as those in FIG. Reference numeral 48 denotes a focus error signal height storage circuit during search.
[0025]
  In the figure, 12 to 18 are the same as those in FIG. 2, and 48 denotes a focus error signal height storage circuit at the time of focus search. In the figure, the focus error signal obtained from the optical pickup is input to the escape speed detection circuit 12 from the current layer, the jump-in detection circuit 15 to the next layer, and the focus error height storage circuit 48 at the time of search.
  When performing a focus jump in an optical disk reproducing apparatus using a multilayer disk, it is extremely difficult to perform a focus jump stably if a fixed pulse is used. Therefore, the current focus control is performed by the escape speed detection circuit 12 from the current layer. From the layerProlapseThe exit speed is detected, and the kick pulse height determination circuit 13 determines the height or width of the kick pulse that can stably perform a focus jump to the next layer. Based on this determination, a kick pulse can be generated by the kick pulse generation circuit 14. At this time, the height of the focus error signal at the time of focus search is stored, and the height or width of the kick pulse is varied in relation to this height. Further, the next layer jump detection circuit 15 moves to the next layer.FlyingThe jumping time or jumping speed is detected, and the brake pulse height determining circuit 16 determines the height of the brake pulse. Based on this determination, a brake pulse is generated by the brake pulse generation circuit 17 and added by the variable kick pulse and the adder 18 to obtain a kick pulse and a brake pulse necessary for a stable focus jump in the multilayer disk. be able to.
[0026]
  FIG. 17 is a diagram showing a stored focus error signal and a variable kick pulse when the focus error height storage circuit 48 at the time of search is used. In the figure, 49 is a focus error signal stored in the storage circuit 48, 50 Is a variable kick pulse, O is a half value of the maximum amplitude of the focus error signal, and indicates the time taken from generation of the T5 kick pulse to O. In the figure, the maximum amplitude value of the focusler signal 49 is stored, and when the value reaches O, which is half the amplitude value, the height or width of the kick pulse that has already been generated can be varied to make it more stable. And you can jump into the next layer with certainty. Normally, by changing the width of the kick pulse, it is possible to jump to the next layer stably during the focus jump operation, but the same effect can be obtained by applying a variable kick pulse height . Also, the same effect can be obtained by using the focus jump circuit having the configuration shown in FIG. 16 during the focus jump operation from the second layer to the first layer. In this way, when detecting the escape speed from the focus error signal, the sensitivity of the focus error signal varies due to variations in laser power and disc reflectivity by using a normalized value instead of a constant threshold voltage. Even if it can be detected accurately.
[0027]
Embodiment 6 FIG.
Figure18 is a block diagram of a focus servo circuit of a recording / reproducing and reproducing apparatus using a multilayer disk according to a sixth embodiment of the present invention. In the figure, 51 is a focus servo compensation circuit, 52 is a focus jump circuit according to the first to fifth embodiments, 53 is an adder, 54 is a filter, 55 is a storage circuit for storing a drive voltage when performing focus control, and 56 is a switch. A switch, 57 is a focus actuator driver, 58 is a focus actuator, and 59 is a CPU that instructs the generation timing of a kick pulse at the time of a focus jump.
[0028]
  Next, the operation of FIG. 18 will be described. The focus error signal detected from the optical pickup is input to the focus servo compensation circuit 51 and the focus jump circuit 52, and the respective outputs are added by the adder 53 to perform normal focus control and The focus jump in this invention can be performed. The focus jump circuit 52 instructed by the CPU 59 for the focus jump timing stores the focus drive voltage when the focus jump is performed through the filter 54 using the storage circuit 55. With the above configuration, the changeover switch 56 can switch to either the output from the adder 53 or the focus drive voltage stored when the focus jump is performed. Each signal is configured to drive a focus actuator 58 via a focus actuator driver 57.
[0029]
  FIG. 19 shows a focus drive voltage at the time of focus control in a recording / reproducing apparatus using a multilayer film disk, a first layer surface touch, and a surface shake in the second layer, 60 is a focus drive voltage waveform, 61 shows the surface runout in the first layer, and 62 shows the runout waveform in the second layer. In the figure, it can be seen that the drive voltage of the focus actuator that follows the surface vibration of the disk has a waveform having the same periodicity as the periodicity of the disk.
[0030]
  Next, a sixth embodiment in which the focus jump voltage can be stably and reliably performed by storing the focus drive voltage using the filter 54 and the storage circuit 55 will be described in more detail with reference to FIG. In the figure, 63 is a focus error signal, 64 is a kick brake pulse, 65 is a focus drive voltage waveform obtained by adding the kick brake pulse, and T6 is the time from the end of the kick pulse to the occurrence of the brake pulse. When the focus jump operation is performed, the drive voltage immediately before the kick pulse is generated is stored in the storage circuit 55 in FIG. 18, so that the focus drive voltage immediately before the kick pulse in the kick brake pulse 64 in FIG. The voltage can be the same as the voltage during the time T6 until the brake pulse is generated. From the above, the focus drive voltage follows the disc runout as described with reference to FIG. 19 and changes with periodicity in the same way as the disc runout. In addition, when the focus jump is performed from the current layer to the next layer in the multilayer disk by holding the voltage during T6, it is extremely stable when the next layer enters. A focus jump can be performed reliably. If the drive voltage is set to the reference voltage level between the kick pulse and the brake pulse, and the drive current of the focus actuator is stopped, the actuator inertia force and kick pulse before kicking regardless of the disk runout or orientation Thus, the actuator is driven only by the driving force by the brake pulse, and the driving force for following the surface deflection of the disk is lost before the brake after the kick. Therefore, the focus actuator immediately before the focus jump can maintain the follow-up ability with respect to the surface deflection of the disk by holding the drive voltage during the jump. At this time, it is needless to say that it is desirable to perform filtering so that noise is not sampled at the time of voltage detection immediately before the focus jump and is not included in the drive signal. Further, the same effect can be obtained by making the average value of the focus drive voltage from an arbitrary time until the kick pulse occurs and the voltage during the time T6 from the end of the kick pulse to the occurrence of the brake pulse. Can do.
[0031]
【The invention's effect】
  Since the present invention is configured as described above, the following effects can be obtained.
[0032]
FFocus jump from the current layer to the next layer in the multilayer disc is stable and reliable by applying an auxiliary pulse to the brake pulse when the brake is too strong at the end of the focus jump and when the brake is too weak It can be performed.
[0033]
[Brief description of the drawings]
FIG. 1 is a block diagram of a recording / reproducing apparatus using a multilayer disk according to a first embodiment of the present invention, and a focus servo circuit of the reproducing apparatus.
FIG. 2 is a block diagram of a recording / reproducing apparatus using a multilayer disk and a focus jump circuit of the reproducing apparatus according to the first embodiment of the present invention.
FIG. 3 is a view showing waveforms of a focus error signal, a kick pulse, and a brake pulse when performing a focus jump from the first layer to the second layer in the multilayer disc according to the first embodiment of the present invention. .
FIG. 4 is a diagram showing waveforms of a focus error signal, a kick pulse, and a brake pulse when performing a focus jump from the second layer to the first layer in the multilayer disc according to the first embodiment of the present invention. .
FIG. 5 is a block diagram of a recording / reproducing apparatus using a multilayer disk according to a second embodiment of the present invention and a focus jump circuit of the reproducing apparatus.
FIG. 6 is a view showing waveforms of a focus error signal, a kick pulse, and a brake pulse when performing a focus jump from the first layer to the second layer in the multilayer film according to the second embodiment of the present invention. .
FIG. 7 is a view showing waveforms of a focus error signal, a kick pulse, and a brake pulse when performing a focus jump from the second layer to the first layer in the multilayer disc according to the second embodiment of the present invention. .
FIG. 8 is a block diagram of a recording / reproducing apparatus using a multilayer disk according to a third embodiment of the present invention and a focus jump circuit of the reproducing apparatus.
FIG. 9 shows a focus when a brake is too strong during a focus jump operation from the first layer to the second layer of a recording / reproducing apparatus using a multilayer disk according to a third embodiment of the present invention; It is the figure which showed the brake pulse which applied the error signal and the auxiliary pulse.
FIG. 10 shows a focus when the brake is too weak during a focus jump operation from the first layer to the second layer of the recording / reproducing apparatus using the multilayer disk according to the third embodiment of the present invention; It is the figure which showed the brake pulse which applied the error signal and the auxiliary pulse.
FIG. 11 shows a focus when the brake is too strong during the focus jump operation from the second layer to the first layer of the recording / reproducing apparatus using the multilayer disk according to the third embodiment of the present invention; It is the figure which showed the brake pulse which applied the error signal and the auxiliary pulse.
FIG. 12 shows a focus when the brake is too weak during the focus jump operation from the second layer to the first layer of the recording / reproducing apparatus using the multilayer disk according to the third embodiment of the present invention; It is the figure which showed the brake pulse which applied the error signal and the auxiliary pulse.
FIG. 13 is a block diagram of a recording / reproducing apparatus using a multilayer disc according to a fourth embodiment of the present invention and a focus jump circuit of the reproducing apparatus.
FIG. 14 shows a focus error signal and a kick pulse brake pulse during a focus jump operation from the first layer to the second layer of a recording / reproducing apparatus using a multilayer disc according to a fourth embodiment of the present invention; It is the figure which showed these waveforms.
15 shows a focus error signal and a kick pulse brake pulse during a focus jump operation from the second layer to the first layer of a recording / reproducing apparatus using a multilayer disc according to a fourth embodiment of the present invention; FIG. It is the figure which showed these waveforms.
FIG. 16 is a block diagram of a recording / reproducing apparatus using a multilayer disc according to a fifth embodiment of the present invention and a focus jump circuit of the reproducing apparatus.
FIG. 17 shows the focus error signal stored when the focus error height storage circuit at the time of focus search is used in the recording / reproducing apparatus and the reproducing apparatus using the multilayer film according to the fifth embodiment of the present invention, and is varied. It is the figure which showed the waveform of the kick pulse.
FIG. 18 is a block diagram of a recording / reproducing apparatus using a multilayer disk according to a sixth embodiment of the present invention and a focus servo circuit using a storage circuit of the reproducing apparatus.
FIG. 19 is a recording / reproducing apparatus using a multilayer film disc according to a sixth embodiment of the present invention, and a focus drive voltage at the time of focus control, a first layer touch and a second layer surface shake in the reproducing apparatus. FIG.
FIG. 20 is a diagram showing a focus error signal, a kick brake pulse, and a focus drive voltage during a focus jump operation in a recording / reproducing apparatus using a multilayer disk according to a sixth embodiment of the present invention and a reproducing apparatus.
FIG. 21 is a diagram showing a specific example of a conventional focus servo circuit.
FIG. 22 is an overall configuration diagram of a recording / reproducing and reproducing apparatus using a conventional optical disc.
FIG. 23 is a diagram showing the structure of a conventional optical disc.
FIG. 24 is a diagram showing a focus error signal at the time of a focus jump of a conventional optical disc.
[Explanation of symbols]
  DESCRIPTION OF SYMBOLS 1 Multi-layer optical disk, 2 Disc motor, 3 Optical pick-up, 4 Focus error amplifier, 5 Focus loop low-pass compensation filter, 6 Focus loop phase compensation filter, 7 Focus search pull-in circuit, 8 Focus jump circuit, 9 Changeover switch, 10 Focus Actuator driver, 11 Focus actuator, 12 Escape speed detection circuit from the current layer, 13 Kick pulse height determination circuit, 14 Kick pulse generation circuit, 15 Dive time speed detection circuit to the next layer, 16 Brake pulse height determination circuit, 17 brake pulse generation circuit, 18 adder, 19 focus error signal, 20 kick pulse brake pulse waveform, 21 jump pulse and kick pulse, 22 blur 24 pulse, 23 focus error signal, 24 kick pulse brake pulse waveform, 25 kick pulse, 26 brake pulse, 27 kick pulse brake pulse waveform, 28 jump pulse and kick pulse, 29 brake pulse, 30 kick pulse brake pulse waveform, 31 jump pulse Kick pulse, 32 brake pulse, 33 overshoot undershoot detection circuit, 34 auxiliary pulse generation circuit, 35 focus error signal, 36 brake pulse, 37 focus error signal, 38 brake pulse, 39 focus error signal, 40 brake pulse, 41 Focus error signal, 42 Brake pulse, 43 Time measurement circuit, 44 Focus error signal, 45 Kick-up Scratch pulse waveform, 46 Focus error signal, 47 Kick brake pulse waveform, 48 Focus error signal height memory circuit during focus search, 49 Focus error signal, 50 Kick pulse, 51 Focus servo compensation circuit, 52 Focus jump circuit, 53 Adder, 54 filter, 55 memory circuit, 56 changeover switch, 57 focus actuator driver, 58 focus actuator, 59 CPU (central processing unit), 60 focus drive voltage waveform, 61 surface shake waveform in first layer, 62 second Surface wobble waveform in layer, 63 Focus error signal, 64 kick brake pulse, 65 Focus drive voltage waveform, 66 Optical disc, 67 Disc mode 68, disc motor servo, 69 laser diode, 70 objective lens, 71 focusing actuator, 72 tracking actuator, 73 photodetector, 74 pickup feeding mechanism, 75 auto laser power control, 76 focusing servo, 77 tracking servo, 78 pickup feeding Servo, 79 multilayer optical disc, 80 second layer information recording surface, 81 first layer information recording surface, 82 optical pickup, 83 optical pickup, 84 focus error signal waveform when performing focus jump from current layer to next layer, 85 In-focus in current layer, 86 In-focus in next layer, 87 Focus error signal from in-focus in current layer to in-focus of next layer, 88 Pickup light detection diode De, 89 current - voltage converting circuit, 90 a subtraction circuit, 91 a phase compensation circuit, 92 a switch, 93 a drive circuit and pick UP / DOWN circuit, 94 pickups UP / DOWN signal, 95 a focus actuator, 96 autofocus detection circuit.

Claims (1)

In an optical disc apparatus for recording / reproducing a multilayer optical disc having a plurality of information recording / reproducing surfaces,
Light detection means;
Focus error generating means for generating a focus error signal from the light detecting means;
Focus control means corresponding to optical disc surface shake from the focus error signal;
A focus jump generating means for generating a kick pulse and a brake pulse for performing a focus jump from the current layer to the next layer in response to the focus error signal;
A focus search pull-in means by the focus error signal;
Switching means for switching the output from the focus jump generating means and the output from the focus control means to a signal from the focus search pull-in means;
A focus driving means for driving with an output from the switching means;
The focus jump generating means includes
Escape speed detection means for detecting the escape speed from the current layer by the focus error signal;
Kick pulse height determining means for determining the height of the kick pulse and the width of the kick pulse from the output from the escape speed detecting means;
Kick pulse generating means for generating a kick pulse by the output from the kick pulse height determining means;
Brake pulse generating means for generating a brake pulse of a predetermined height and width when the focus error signal reaches a predetermined signal level determined based on a maximum amplitude stored in advance ;
Based on the maximum amplitude of the focus error signal, an upper limit value and a lower limit value of the signal level of the predetermined focus error signal are determined. Overshoot and undershoot detection means for detecting as an overshoot of the focus error signal when it is higher than the upper limit value of the signal level and detecting as an undershoot of the focus error signal when lower than the lower limit value of the predetermined signal level When,
When the detection result of the overshoot and undershoot detection means indicates an overshoot, an auxiliary pulse for further braking is generated, and when the detection result indicates an undershoot, it is further opposite to the brake pulse. A focusing device in an optical disc apparatus, comprising: an auxiliary pulse generating means for generating an auxiliary pulse of polarity .

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