JP5034643B2 - Optical disk device - Google Patents

Description

  The present invention relates to an optical disc apparatus for recording or reproducing information on an optical disc.

In the optical disc apparatus, in order to move the lens position to a track for recording / reproducing of the optical disc, a short jump is performed in which the zero cross of the tracking error is counted and moved to a predetermined track. This jump is not faster than a long jump that moves only by a thread (coarse motion), but has the feature that it can move the exact number of tracks. Conventionally, it has been devised so that many tracks can be moved by one short jump (see, for example, Patent Documents 1 and 2 below).
Japanese Patent No. 2899505 JP-A-9-63069

  However, the conventional apparatus described above has the following problems. In Patent Document 1, short jumping and tracking are alternately performed, and a thread is controlled based on a tracking error at that time. Therefore, it is not possible to jump many tracks continuously. Further, in Patent Document 2, since the lens is sent at an average speed during a short jump, the appropriate value may change depending on the individual machine, environmental temperature, etc., and the lens position may gradually shift, causing the short jump to fail. .

  The present invention has been made in view of the above points, and can stably realize a short jump of a large number of tracks, and can realize a short jump of a large number of tracks satisfactorily even if the difference between each machine or the environmental temperature is different. An object is to obtain an optical disk device.

As means for achieving the above object, an optical disc apparatus according to the present invention comprises a pickup for writing information on or reading information from an optical disc, and a pickup adjusting means for performing tracking control and focus control of the pickup. A disk rotating means for rotating the optical disk, a thread motor for allowing the pickup to move to a desired track of the optical disk rotating by the optical disk rotating means, and a light receiving device constituting the pickup driven by the thread motor. A lens error detection means for detecting a lens error signal whose signal level changes in accordance with a position displacement in the track width direction of an objective lens constituting the pickup from an output signal obtained by receiving light at a unit, and at the time of a short jump, the lens Error detection means Based on the result of comparison between a plurality of threshold signal levels of the lens error signal output are pre-set, from among the plurality of moving speed which is set in advance of the objective lens which moves along with the short jump Control means for selecting a moving speed at any time so that the position is near the center of the movable range and controlling the sled motor at the selected moving speed is provided.

  According to the present invention, a short jump with a large number of tracks can be realized stably, and a short jump with a large number of tracks can be realized satisfactorily even if the difference between each machine or the environmental temperature is different.

  The optical disk apparatus of the present invention will be described below. FIG. 1 is a block diagram showing a configuration of a preferred embodiment of an optical disc apparatus according to the present invention. In FIG. 1, an optical disk 101 is held in a detachable state on a flange 104 fixed to a shaft 103 of a spindle motor 102 that rotates the optical disk. The rotation speed of the spindle motor 102 is controlled so that a predetermined linear velocity is obtained at the spot position of the light beam. Further, the FG signal having a frequency proportional to the disk rotation phase output from the spindle motor 102 is used for detecting a speed signal in the rotation control by the microcomputer 113 as the control means.

  The pickup 105 includes a laser diode 106, a light receiving unit 107 including a plurality of photodiodes, a half mirror, an objective lens, and a magnet (not shown), and a movable unit that can be displaced in the tracking direction and the focus control direction. It comprises a tracking coil 108 and a focus coil 109 for control.

  Further, the entire pickup 105 is configured to be movable in the radial direction of the disk 101. This is realized by the microcomputer 113 controlling the thread motor 110 attached to the lead screw 111 screwed with the female screw portion attached to the pickup 105 via the drive circuit 112.

  The laser light emitted from the laser diode 106 is irradiated onto the disk 101 via the objective lens, and is modulated and reflected by the recording signal and the guide groove. This light is incident on the light receiving unit 107 through a half mirror. The beam is composed of three beams by an optical system such as a diffraction grating (not shown in detail). The analog signal processing circuit 114 detects and outputs the tracking error signal TE, the focus error signal FE, and the lens error signal LE from the signal photoelectrically converted by the pickup 105. Further, these output signals are converted from analog to digital by the AD converters 118 to 120 and input to the microcomputer 113.

  FIG. 2 is a detailed explanatory diagram of the light receiving unit 107 and the analog processing circuit 114. Here, A, B, C, D, E, F, G, and H are outputs of one quadrant photodiode and two photodiodes constituting the light receiving unit 107, and the analog processing circuit 114 is known. The tracking error signal TE, the focus error signal FE, and the lens error signal LE can be obtained by performing the following analog calculation by the above method.

FE = ((a + c)-(b + d)
TE = ((a + d) − (b + c)) + ((e−f) + (g−h))
LE = ((a + d) − (b + c)) − ((e−f) + (g−h))

  An output proportional to the amount of movement of the lens in the tracking direction can be obtained from the lens error signal LE. In the midpoint servo, this lens error signal is used as a servo error signal, an error signal is obtained using the lens error signal LE at the lens center position as a target value, and this is feedback controlled. Thereby, even when the sled is moved, the lens is positioned at the center position without vibrating.

  In FIG. 1, the tracking error signal TE is converted from analog to digital by an AD converter 118 and taken into the microcomputer 113. Similarly, the focus error signal FE is converted from analog to digital by the AD converter 119 and taken into the microcomputer 113. The lens error signal LE is taken into the microcomputer 113 via the AD converter 120.

  The microcomputer 113 is connected to a ROM, and stores programs and fixed data. A RAM is also connected to store variable values and the like. Further, a flash ROM for storing initial setting values and the like is connected.

  Further, the DA converter 121 is connected to the microcomputer 113, outputs data obtained by calculating the tracking control drive signal, and drives the tracking control coil 108 via the drive circuit 123 with this value. Similarly, a DA converter 122 is connected to the microcomputer 113, outputs data obtained by calculating a focus control drive signal, and drives the tracking control coil 109 via the drive circuit 124 with this value.

  Further, an inner peripheral switch 117 is attached to the fixed portion, and when the movable portion reaches the innermost peripheral position due to the movement of the sled, the switch is turned on, and this is read and detected by the microcomputer 113.

FIG. 3 is an explanatory diagram of a short jump operation. (A) is a tracking error waveform, (b) is a tracking coil drive waveform, and (c) is a tracking actuator control mode. The disk 101 has an eccentricity, and a sine wave waveform corresponding to the eccentricity is seen in the tracking drive waveform shown in FIG. Time t ₃₁ before a following operation state by the tracking control, the acceleration pulse occurs at time t _31, to start the short jump. Until time t ₃₂ , speed control is performed by moving speed error data obtained by comparing the zero-crossing period of the tracking error signal TE with a predetermined target period time. At time t ₃₂ , a deceleration pulse is generated to make the lens moving speed almost zero, and then the control is switched to tracking control to complete the short jump.

  FIG. 4 shows the waveform of the lens error signal LE in the short jump speed control state during reproduction of the eccentric disk in the conventional example. In this embodiment, the higher level (voltage) of the lens error signal LE is the outer peripheral side, and the lower level is the inner peripheral side.

  In short jump, it is desirable that the lens be near the center of the movable range of the actuator in order to operate stably. That is, it is desirable that the sled move at the same speed as the lens moves.

  In the present invention, four threshold values are provided for the lens error signal LE symmetrically about the vicinity of the center position of the lens movable range. That is, in FIG. 4, the level VH1 is a threshold value slightly before the upper limit at which the jump can be maintained, the level VL1 is a threshold value slightly before the lower limit at which the jump can be maintained, and the level VH0 is a threshold value slightly before the upper limit at which the jump can be successfully performed. The level VL0 indicates a threshold value slightly before the lower limit at which a good jump can be made.

  That is, if the level of the lens error signal LE is between the level VH0 and the level VL0, the short jump works well, and if it is between the level VH1 and the level VL1, the jump does not fail.

  In the conventional example of FIG. 4, since the moving speed of the sled is a predetermined value, the deviation gradually occurs when the number of tracks increases, and finally the controllable range is exceeded and the jump fails.

FIG. 5 is a flowchart showing an outline of the operation of the present embodiment. This flowchart is a short jump control flowchart by the microcomputer 113 as the control means. A short jump is started at a time corresponding to time t _{31 in} FIG. 3 to generate an acceleration pulse. Then, the control shifts to speed control based on the zero-cross cycle of the tracking error signal TE (step S501). Next, control of the sled motor 110 is started (step S502). Then, it is checked whether or not the predetermined number of tracks have been skipped (step S503), and if not finished, the thread speed control process is continued. When the predetermined number of tracks is skipped, the process proceeds to a short jump end process (step S505). After generating a deceleration pulse, switch to tracking control.

  FIG. 6 shows a flowchart of thread speed control processing by the microcomputer 113 as the control means. First, the lens error signal LE is read from the AD converter 120 (step S601). Next, it is checked whether the level of the lens error signal LE is “VH0 or more and less than VH1” (step S602). If true, the thread movement speed setting speed SPEED is set to a speed SPH0 that is slightly faster than the lens movement average speed (step S603). Next, it is checked whether the level of the lens error signal LE is “VL0 or less and exceeds VL1” (step S604). If true, the sled moving speed setting speed SPEED is set to a speed SPL0 that is slightly slower than the lens moving average speed (step S605). Next, it is checked whether the level of the lens error signal LE is “VH1 or higher” (step S606). If true, the setting speed SPEED of the thread movement speed is set to a speed SPH1 that is faster than the speed SPH0 (step S607). Next, it is checked whether the level of the lens error signal LE is “VL1 or less” (step S608). If true, the thread movement speed setting speed SPEED is set to a speed SPL1 that is slower than the speed SPL0 (step S609).

This operation will be described with reference to waveform diagrams of FIGS. FIG. 7 shows a state in which the level of the lens error signal LE is in the range of VH0 to VL0 and jumps well. 8, in order to level the lens error signal LE exceeds VH0 at time t _81, as the speed SPH0 set speed SPEED thread movement speed by the processing in step S603, gradually lens is moving toward the center.

9, to the level of the lens error signal LE falls below VL0 at time t _91, as the speed SPL0 set speed SPEED thread movement speed by the processing in step S605, gradually lens is moving toward the center.

10, in which the level of the lens error signal LE due disturbance exceeds rapidly VH0, VH1, due to exceeding the VH0 at time t _101, the speed set speed SPEED thread movement speed by the processing in step S603 SPH0 as further to at time t ₁₀₂ exceeds VH1, it is rapidly increase the speed set speed sPEED thread travel speed as the speed SPH1 by the processing in step S607. In order to become less than VH1 at time t _103, the speed SPH0 set speed SPEED thread movement speed by the processing in step S603, gradually lens is moving toward the center.

11, in which the level of the lens error signal LE due disturbance exceeds rapidly VL0, VL1, due to exceeding the VL0 at time t _111, the speed set speed SPEED thread movement speed by the processing in step S605 SPH0 as further, to below the VL1 at time t _112, it is drastically reduced rpm setting speed sPEED thread travel speed as the speed SPL1 by the processing in step S609. Then, due to exceeding the VL1 at time t _113, the speed SPL0 set speed SPEED thread movement speed by the processing in step S605, gradually lens is moving toward the center.

  FIG. 12 shows a flowchart according to another embodiment of the present invention, corresponding to the flowchart shown in FIG. The operation of this embodiment is similar to that of the embodiment shown in the flowchart of FIG. 6. However, when the level range of the lens error signal LE is in the range of VL0 to VH0 (after step S1208), the sled movement speed is changed. The set speed SPEED is set to SPEED = SPM (average speed set value). In the embodiment of FIG. 6, the lens moves so as to reciprocate between VL0 and VH0, but in this embodiment, the movement of the lens is reduced.

13 to 16 show waveform diagrams of the operation. 13, above the level of the lens error signal LE VH0 at time t _131, the set speed SPEED thread movement speed in step S1203 shown in FIG. 12 is set to a speed SPH0, the lens error signal LE at time t ₁₃₂ Since the level is less than VH0, the sled moving speed setting speed SPEED is the speed SPM.

14, the level of the lens error signal LE exceeds the VL0 at time t _141, the set speed SPEED thread movement speed is set to speed SPL0 in step S1205, the level of the lens error signal LE VL0 at time t ₁₄₂ Since it has exceeded, the setting speed SPEED of the sled movement speed becomes the speed SPM.

15, in which the level of the sudden lens error signal LE due disturbance exceeds VH0, VH1, due to exceeding the VH0 at time t _151, the speed set speed SPEED thread movement speed by the processing in step S1203 SPH0 as further to the level of the lens error signal LE exceeds VH1 at time t _152, are rapidly increase the speed set speed sPEED thread movement speed as SPH1 the processing of step S1207. From time t ₁₅₃ to time t _{154, the} thread movement speed setting speed SPEED is set to the speed SPH0 by the process of step S1503, and from time t ₁₅₄ to time t _{155, the} thread movement speed setting speed SPEED is set to the speed SPM by the process of step S1210. as time t ₁₅₅ ~ time t ₁₅₆ as speed SPH0 set speed sPEED thread movement speed by the processing in step S1203, after time t ₁₅₆ is a speed SPM set speed sPEED thread movement speed by the processing in step S1210.

16, in which the level of the sudden lens error signal LE due disturbance exceeds VL0, VL1, due to exceeding the VL0 at time t _161, the speed set speed SPEED thread movement speed by the processing in step S1205 SPL0 as further due to exceeding the VL1 at time t _162, it is rapidly slow down the set speed sPEED thread travel speed as the speed SPL1 the processing of step S1209. From time t ₁₆₃ to time t _{164, the} thread movement speed setting speed SPEED is set to the speed SPL0 by the process of step S1507, and from time t ₁₆₄ to time t _{165 the} thread movement speed setting speed SPEED is set to the speed SPM by the process of step S1210. as time t ₁₆₅ ~ time t ₁₆₆ as speed SPL0 set speed sPEED thread movement speed by the processing in step S1207, after time t ₁₅₆ has a set speed sPEED threads moving speed as SPM by the processing in step S1210.

  In this way, when the jump is likely to be outside the range that can be maintained, the speed of the thread is suddenly changed. Can be controlled.

  In the present invention, as described above, four thresholds are provided for determining the lens position and controlling the sled moving speed, but it is possible to set the speed more finely by setting a larger number. Further, the operation can be performed with two settings of the upper side 1 and the lower side 1.

  In the present invention, a lens error signal is used as the lens position detection means, but a dedicated sensor such as a photo reflector may be used. Further, the tracking coil driving waveform in FIG. 3 may be used. If this waveform is passed through a low-pass filter, it is more suitable because high-frequency noise is attenuated.

  The present invention can be applied to various optical disc recording / reproducing apparatuses such as a DVD player / recorder and a BD player / recorder.

1 is a block diagram showing a configuration of a preferred embodiment of an optical disc device according to the present invention. FIG. 2 is a detailed explanatory diagram of a light receiving unit 107 and an analog processing circuit 114 in FIG. 1. It is explanatory drawing of operation | movement of the short jump for demonstrating embodiment of this invention. It is a figure which shows the waveform of the lens error signal LE in the speed control state of the short jump at the time of eccentric disk reproduction | regeneration in a prior art example. FIG. 3 is a flowchart illustrating control of a short jump by a microcomputer 113 as a control unit, which represents an outline of an operation according to an embodiment of the present invention. FIG. 3 is a flowchart of thread speed control processing by a microcomputer 113 serving as control means, showing an outline of the operation of the embodiment of the present invention. It is a wave form chart at the time of sled speed control in case the level of lens error signal LE for describing an embodiment of the invention exists in the range of VH0-VL0. Is a waveform diagram when the thread speed control when the level of the lens error signal LE for describing the embodiments exceeds VH0 at time t ₈₁ of the present invention. It is a wave form chart at the time of thread speed control when the level of lens error signal LE for describing an embodiment of the invention falls below VL0. It is a waveform diagram at the time of thread speed control when the level of the lens error signal LE suddenly exceeds VH0 and VH1 due to disturbance or the like for explaining the embodiment of the present invention. It is a waveform diagram at the time of thread speed control when the level of the lens error signal LE suddenly exceeds VL0, VL1 due to a disturbance or the like for explaining the embodiment of the present invention. FIG. 9 is a flowchart of thread speed control processing by a microcomputer 113 as a control unit, which represents an outline of the operation of another embodiment of the present invention. It is a wave form chart at the time of thread speed control in case the level of lens error signal LE for describing an embodiment of the invention exceeds VH0. It is a wave form chart at the time of thread speed control when the level of lens error signal LE for describing an embodiment of the invention exceeds VL0. It is a waveform diagram at the time of thread speed control when the level of the lens error signal LE suddenly exceeds VH0 and VH1 due to disturbance or the like for explaining the embodiment of the present invention. It is a waveform diagram at the time of thread speed control when the level of the lens error signal LE suddenly exceeds VL0, VL1 due to disturbance or the like for explaining the embodiment of the present invention.

Explanation of symbols

101 optical disk 102 spindle motor (disk rotating means)
105 Pickup 108, 109 Coil (Pickup adjustment means)
110 Thread motor 113 Microcomputer (control means)
114 Analog signal processing circuit (lens error detection means)

Claims (3)

A pickup for writing information to or reading information from an optical disc;
Pickup adjustment means for performing tracking control and focus control of the pickup;
Disk rotating means for rotating the optical disk;
A sled motor that enables the pickup to move to a desired track of the optical disk rotated by the optical disk rotating means;
A lens error signal whose signal level changes according to a position displacement in the track width direction of the objective lens constituting the pickup is detected from an output signal obtained by receiving light at a light receiving portion constituting the pickup driven by the thread motor. Lens error detection means;
Based on a comparison result between a signal level of the lens error signal output from the lens error detection means and a plurality of preset threshold values at the time of a short jump, the short circuit is selected from a plurality of preset moving speeds. A control means for selecting at any time a moving speed such that the position of the objective lens moving with the jump is near the center of the movable range, and controlling the sled motor at the selected moving speed ;
Optical disk device provided. The control means, as the plurality of threshold values, a first threshold value that is a signal level corresponding to a limit position in the advance direction of the pickup , with an average moving speed of the pickup to be followed at the time of the short jump, the second threshold is the signal level corresponding to the delay direction limit position of the pickup, a third threshold value exceeding the first threshold, set the fourth threshold value exceeding the second threshold value, the pickup As a moving speed, when the signal level corresponding to the lens position exceeds the first threshold during the short jump, the first speed is slightly faster than the average speed of the pickup to be followed during the short jump, average speed when the signal level corresponding to the lens position is greater than the second threshold value, the pickup should follow during short jump Ri slightly slower second speed, when the signal level corresponding to the lens position is greater than the third threshold value, the faster than the first speed third speed, the signal level corresponding to the lens position said first 2. The optical disk apparatus according to claim 1, wherein when the threshold value of 4 is exceeded, the sled motor is controlled at a fourth speed slower than the first speed. Wherein, during the short jump, when the signal level corresponding to the lens position is in the range of the first threshold and the second threshold value, the pickup the thread motor, to be followed during short jump The optical disk apparatus according to claim 2, wherein the optical disk apparatus is controlled at an average speed.

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