JP4099560B2 - Optical disk device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk apparatus, and more particularly to an optical disk apparatus that is highly sensitive to vibrations and scratches on a disk, and that detects both of them and reliably prevents erroneous recording. is there.
[0002]
[Prior art]
An optical disc device is a device that records data on an optical disc and reproduces the data recorded on the optical disc.
Here, with reference to FIG. 4, an outline of a configuration of an example of a conventional optical disc apparatus will be described.
The conventional optical disc apparatus 20 basically has a spindle motor 2 that rotates the optical disc 1, an optical head 3 that irradiates the optical disc 1 with laser light during recording / reproduction, a radial direction of the optical disc 1, and an approach / separation to the optical disc 1. A biaxial mechanism 4 that displaces the objective lens 3 a of the optical head 3 in the direction, a sled mechanism 5 that moves the optical head 3 in the radial direction of the optical disk 1, and a magnetic head 6 that applies a modulated magnetic field to the optical disk 1. Yes.
[0003]
Also, an RF amplifier 7 that outputs required data based on data input from the optical head 3, a servo circuit 9 that functions as a feedback control device for the optical head 3, and a system controller that functions as a control device for the entire optical disk device 20. (CPU) 11.
The RF amplifier 7 outputs a tracking error signal, a focus error signal, and the like by calculation processing of information supplied from the optical head 3. The servo circuit 9 generates necessary servo drive signals based on the tracking error signal, the focus error signal, and the like output from the RF amplifier 7 and the system controller 11, and controls the biaxial mechanism 4 and the sled mechanism 5 to perform focus control. In addition, tracking control is performed, and the spindle motor 2 is controlled to rotate at a constant angle or a constant linear velocity.
[0004]
Further, although not described, the optical disc apparatus 20 includes an encoder / decoder 8, an address decoder 10, a memory controller 12, a RAM 13, a magnetic head drive mechanism 15, and the like.
[0005]
As described above, in such an optical disc apparatus, the recording area to be magnetized by the magnetic head 6 is determined by the recording laser light from the optical head. That is, in order to perform proper recording along the recording track, the tracking servo control of the optical head needs to be accurately performed by the servo circuit 9.
[0006]
By the way, if an external vibration or impact is applied during the recording operation of the optical disc apparatus, the tracking servo of the optical head is released and a track jump occurs. When a track jump occurs, the optical head moves from the track to be recorded to another track during the recording operation, and data is recorded on another track different from a predetermined regular track. Also, if data has already been recorded on the destination track, that data will be erased by mistake.
For normal scratches, it is necessary to record data correctly.
[0007]
Therefore, conventionally, in the optical disk apparatus, in order to detect a defect of the optical disk, a change in the light amount of the focus is measured, and when the light amount change is large, it is determined that the optical disk has a defect (scratch).
In addition, in order to detect an optical disc shock caused by a disturbance, the product of the tracking error signal voltage and the off-track signal voltage is detected. If the product is large, it is determined that a tracking error has occurred. Was.
Further, as another method, there is proposed a method in which a base unit having a recording head is made swingable and its displacement is measured to measure external vibration and impact.
[0008]
[Problems to be solved by the invention]
However, the conventional optical disk defect detection method and shock detection method have the following problems.
The first problem is that when a shock in the focus direction of the optical head is applied to the optical disk, a signal indicating that a defect has been detected is generated because the amount of focus light changes, and the shock is misidentified as a defect.
Secondly, when the defect of the optical disk is large, there is a problem that it is misidentified as off-track and a tracking error signal is output, and the defect is mistaken as a shock.
In the conventional optical disc defect detection method and shock detection method, it is difficult to reliably detect the defect and the shock in this manner, and it is difficult to record data despite vibration disturbances. While there is a possibility of erroneous recording, there is a risk that even a minute scratch may be mistaken for the occurrence of a vibration disturbance and stop data recording.
Although various methods other than the above-described detection methods have been proposed, there are no methods that are economically and technically satisfactory at present.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disc apparatus provided with a detection mechanism capable of clearly distinguishing and recognizing a defect of an optical disc and a shock of the optical disc due to a disturbance or the like so as to prevent erroneous recording.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to a shock detection circuit for detecting external vibration or impact applied to an optical disc, and an optical head in an optical disc apparatus for recording data on an optical disc by an optical head and reproducing the recorded data. A detrack / defocus detection circuit for detecting at least one of detrack and defocus, a first latch circuit to which a detection signal from the shock detection circuit is input to a reset input terminal, and the first latch A second latch circuit in which an output signal from an inverter connected to the output terminal of the circuit is input to a set input terminal and an output signal of the detrack / defocus detection circuit is input to a reset input terminal; Detects the lead signal and outputs it to the optical head. The second latch circuit receives the output signal from the first latch circuit that has detected the output signal from the shock detection circuit and the detrack / defocus detection circuit from the detrack / defocus detection circuit. When an output signal of at least one of the focus is detected, the signal processing circuit includes an AND circuit that interrupts recording of data on the optical disk by the optical head, and the signal processing circuit includes: And a control circuit unit that refreshes the first latch circuit by outputting a control signal at a constant cycle during operation.
[0011]
In the present invention, the detrack (DETRACK) signal is a signal indicating that the optical head is determined to be out of the normal track when the signal value of the tracking error signal is larger than a predetermined value. The defocus (DEFOCUS) signal is a signal indicating that it is determined that the optical head is out of focus when the signal value of the focus error signal is larger than a predetermined value.
[0012]
According to the present invention, in the shock detection circuit , for example, an external vibration or shock (shock) is detected using an acceleration sensor, and then the detrack or defocus of the optical head caused by the optical disk apparatus itself is detected by the detrack / defocus detection circuit. Is detected . Then, triggered by detection of external vibration or shock by the shock detection circuit, the detrack / defocus detection circuit is operated for a predetermined time, and during the operation of the detrack / defocus detection circuit, the detrack and defocus of the optical head When at least one of defocusing is detected, the recording of data on the optical disk by the optical head is interrupted to prevent erroneous recording. In other words, using a detection of external vibration or impact by an acceleration sensor as a trigger, a detrack / defocus detection circuit for detecting detrack or defocus caused by the optical disc apparatus itself is operated for a predetermined time, for example, 100 msec, and the detection is performed. Data recording of the optical head is controlled based on the result. As described above, in the optical disc apparatus according to the present invention, the interruption of data recording due to external vibration or shock (shock) and the continuation of data recording due to detracking or defocusing caused by defects (scratches) of the optical disc are clearly defined. A distinction is made to prevent erroneous recording. When a defect is detected , recording is continued so that the previous servo state is maintained and no servo detachment occurs .
[0013]
In a preferred embodiment of the present invention, the shock detection circuit includes an acceleration sensor that detects external vibration / impact applied to the optical disc, and a first comparator that compares an output signal of the acceleration sensor with a predetermined value. . Since the output of the acceleration sensor is 180 degrees out of phase with the displacement output detected by the detrack / defocus detection circuit , data recording is stopped when there is a displacement abnormality after detection of vibration or impact by the acceleration sensor. However, it will not cause a misrecording.
[0015]
In the present invention, the signal processing circuit includes first and second latch circuits, and a control signal is input from a control circuit unit to a set input terminal of the first latch circuit. When the signal is input, the signal processing circuit is refreshed, the detection output from the shock detection circuit is input to the reset input terminal of the first latch circuit, and the second latch circuit set input terminal An output signal from an inverter connected to the output terminal of the first latch circuit is input, and the detrack / defocus detection circuit supplies the detrack and defocus detection circuits to the reset input terminal of the second latch circuit. When at least one of defocusing is detected, data to the optical disk by the optical head is output by the output signal of the second latch circuit. Interrupting the recording.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described specifically and in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to the present invention, FIG. 2 is a diagram showing a waveform of a control signal, and FIG. 3 is a flowchart showing a signal flow and a process flow.
In addition to the configuration of the conventional optical disk apparatus 20, the optical disk apparatus 30 of the present embodiment includes a shock detection circuit 32 that detects external vibration / impact applied to the optical disk 1, and detracking and defocusing of the optical head 3. A detrack / defocus detection circuit 34 for detecting at least one of the above, and a shock detection circuit 32 and a signal processing circuit 36 for processing a detection signal of the detrack / defocus detection circuit 34.
The shock detection circuit 32 includes an acceleration sensor (G sensor) 38 that detects external vibration / impact applied to the optical disc 1 and a first comparator 40 that compares an output signal of the acceleration sensor with a predetermined value. The detrack / defocus detection circuit 34 also compares the tracking error signal 45 output from the RF amplifier 7 with a predetermined value and the focus error signal 46 output from the RF amplifier 7 in a predetermined manner. And a third comparator 44 for comparing the value.
[0017]
Further, the optical disk device 30 includes, as a signal processing circuit 36, a first latch circuit 48, an inverter 50 connected to the output terminal of the first latch circuit 48, and a second latch connected to the output terminal of the inverter 50. A latch circuit 52 and an AND circuit 54 connected to the output terminal of the second latch circuit 52 are provided.
[0018]
The first latch circuit 48 and the second latch circuit 52 are registers each including, for example, an RS flip-flop, and include a set input terminal S, a reset input terminal R, and an output terminal.
[0019]
A control signal 56 is input from the system controller 11 to the set input terminal S of the first latch circuit 48. On the other hand, the shock detection circuit 32 is connected to the reset input terminal R of the first latch circuit 48 and the output signal of the shock detection circuit 32 is input.
The shock detection circuit 32 includes an acceleration sensor 38, an amplifier that amplifies the output signal of the acceleration sensor 38, and a comparator 40 that generates a low output signal when the output signal exceeds a certain level. 1 detects external vibration / impact applied to 1. The acceleration sensor 38 is a sensor that detects acceleration by measuring an inertial force applied to the mass, and detects an acceleration at a predetermined position of the optical disc 1 and outputs a signal.
[0020]
As shown in FIG. 2, the control signal 56 is a signal having a waveform having a rising pulse at a constant cycle, for example, every 100 msec during operation of the signal processing circuit 36, and the signal processing circuit 36 is refreshed by this rising pulse. is doing.
[0021]
In the first latch circuit 48, when the control signal 56 is low, the output signal is input from the shock detection circuit 32, but the output is high.
[0022]
An inverted signal obtained by inverting the output signal of the first latch circuit 48 by the inverter 50 is input to the set input terminal S of the second latch circuit 52. The detrack / defocus detection circuit 34 is connected to the reset input terminal R of the second latch circuit 52, and an output signal is input.
The detrack / defocus detection circuit 34 includes a second comparator 42 and a third comparator 44, and when at least one of the focus error signal and the tracking error signal, which is a servo signal of the optical head 3, exceeds a certain level. The comparator circuit is configured to generate a low output signal, and detects the tracking servo deviation of the optical head 3.
[0023]
The output signal of the second latch circuit 52 is input to one input terminal of the AND circuit 54, and the write / read signal 58 is input from the system controller 11 to the other input terminal.
The write / read signal 58 is a signal for controlling recording / reproduction of the optical head, and is input from the system controller 11 of the optical disk apparatus.
When servo loss occurs due to external vibration / impact on the optical disc 1, the output signal of the second latch circuit 52 becomes low (Low), the output of the AND circuit 54 is forced low (Low), and recording is interrupted. Switch to playback mode.
[0024]
Next, the overall operation of the signal processing circuit 36 and the signal flow will be described in more detail with reference to FIG.
First, when the control signal 56 is low (Low), the signal at the set input terminal S of the first latch circuit 48 is low (Low), and the output of the first latch circuit 48 is the output of the shock detection circuit 32. Regardless of the output, it is fixed to High.
As a result, the output is inverted by the inverter 50 and the set input of the second latch circuit 52 becomes low, so that the second latch is independent of the output of the detrack / defocus detection circuit 34. The output of the circuit 52 is also fixed to high. Therefore, the write / read signal 58 is output through as the output of the AND circuit 54.
[0025]
Next, when the control signal 56 rises, the first latch circuit 48 becomes operable. Here, when the shock detection circuit 32 detects external vibration and the output becomes low (Low) at that moment, the first latch circuit 48 is set to low (Low). Then, since the rising signal is input to the set input terminal S of the second latch circuit 52, the second latch circuit 52 circuit becomes operable. At this time, when the detrack / defocus detection circuit 34 detects detrack / defocus due to external vibration and the output becomes low at that moment, the second latch circuit 52 is set to low. Is done.
Then, the AND circuit 54 becomes a low output and switches from recording to reproduction.
As described above, it is possible to prevent an erroneous recording caused by a servo shift that occurs during external vibration / impact on the optical disc 1.
[0026]
Next, with reference to FIG. 3, the signal of the signal processing circuit 36 of this embodiment and the flow of processing will be described.
First, in step S _1, as well as to start recording on the optical disk 1, and outputs a control signal 56 from the microcomputer or the like. At the same time, to start the 100msec timer, the process proceeds to step S _2.
In step S _2, at the rising edge of the high (High) from the low control signal 56 (Low), the first latch circuit 48 is operable, the process proceeds to Step S _3.
In the state of step S _3, when detecting the external vibration by the shock detection circuit 32, the process proceeds to step S _4. When not detected, the process proceeds to step S _7.
In step S ₄ , since the output of the first latch circuit 48 becomes low, a rising signal is input to the set input terminal S of the second latch circuit 52, and the second latch circuit 52 becomes operable. , the process proceeds to step S _5.
[0027]
In the state of step S _5, the de-track signal from the de-track / defocus detection circuit 34, or de-focus signal is outputted, the output of the second latch circuit 52, since it is set low (Low), the output of the aND circuit 54, shifts the low (low), and the step S _6. When detrack / defocus detection circuit 34 does not detect both detrack and defocus, the process proceeds to step S _8.
In step S _6, it switched from light to lead.
[0028]
In step S ₇ , the process returns to step S ₃ again unless the timer has passed the set time of 100 msec. When the timer has passed the set time of 100 msec, the process returns to step S ₁ .
In step S ₈ , the process returns to step S ₅ again unless the timer has passed the set time of 100 msec. When the timer has passed the set time of 100 msec, the process returns to step S ₁ .
That is, in steps S ₇ and S ₈ , when the 100 msec timer overflows in the sequence, the control signal 56 is raised again and the signal processing circuit 36 is refreshed.
[0029]
In this embodiment, the relationship between the output signal from the shock detection circuit 32 and the output signal from the detrack / defocus detection circuit 34 is as described below.
The output signal of the shock detection circuit 32 is an acceleration component of external vibration / shock, and the output signal of the detrack / defocus detection circuit 34 corresponds to an optical shift generated when the external vibration / shock is received. .
That is, both output signals are in a relationship between acceleration and displacement, and the acceleration is always 180 degrees in phase with respect to the displacement. Therefore, detrack / defocus detection is performed using the output signal of the shock detection circuit 32 as a trigger. The circuit 34 can start detrack / defocus detection.
[0030]
Further, the control signal 56 used in the present embodiment generates a rising pulse at a predetermined cycle, and the output of the first latch circuit 48 is cleared by this rising pulse.
That is, even if the external latch and the impact are detected and the second latch circuit 52 is in the operating state, and the optical head 3 is neither in the detrack state nor in the defocus state, the first latch circuit is again used. The output of 48 is cleared and the next external vibration / impact is detected.
[0031]
Further, for example, when the optical head 3 is detracked or defocused due to factors other than external vibration / impact, the following occurs.
In general, the optical disk device 30 guarantees recording / reproduction for a scratch of 200 microns or less, for example, although it depends on the type of the optical disk 1. On the other hand, when data is recorded on the optical disk 1 having a scratch of 200 microns or less, a detrack signal is instantaneously generated even though the servo is not displaced. In this case, recording should not be interrupted even if detracking is detected.
In the detrack / defocus detection circuit of the present embodiment, the output of the second latch circuit 52 is fixed to High when there is no external vibration / impact even when detrack is detected. For this reason, the output of the AND 18 remains high, and data recording is continued.
[0032]
Also, when scratches and external vibrations / impacts occur at the same time, in the past, it could not be determined correctly and there was a possibility of erroneous recording due to priority being given to the detrack detection process. With the above-described configuration, it is possible to reliably operate and prevent erroneous recording.
[0033]
The reason why the first and second latch circuits are used in the signal processing circuit 36 is to perform signal processing at high speed. Alternatively, the output of the shock detection circuit 32 and the output of the detrack / defocus detection circuit 34 are connected to the interrupt input of the microcomputer by using a microcomputer capable of processing at a sufficiently high speed so as not to cause malfunction. It is also possible to perform the same control as in this embodiment. In this case, the first latch circuit 48, the second latch circuit 52, and the inverter 50 are unnecessary, and the cost can be reduced.
[0034]
【The invention's effect】
According to the present invention, the first detection circuit for detecting external vibration / impact applied to the optical disc and the second detection circuit for detecting at least one of detrack and defocus of the optical head are provided. When the external vibration / impact is detected by the first detection circuit, recording on the optical disc is stopped by using the detrack signal or the defocus signal output by the second detection circuit as a trigger.
Thereby, detrack detection or defocus detection caused by external vibration / impact can be performed, and erroneous recording occurring at that time can be surely prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to the present invention.
FIG. 2 is a diagram illustrating a waveform of a control signal.
FIG. 3 is a flowchart showing a flow of signals and a flow of processing.
FIG. 4 is a block diagram showing a configuration of a conventional optical disc apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Spindle motor, 3 ... Optical head, 3a ... Objective lens, 4 ... 2-axis mechanism, 5 ... Thread mechanism, 6 ... Magnetic head, 7 ... RF amplifier, 7 ... ... Encoder / decoder, 9 ... Servo circuit, 10 ... Address decoder, 11 ... System controller, 12 ... Memory controller, 13 ... RAM, 15 ... Magnetic head drive, 20 ... Conventional optical disk device, 30 ... Optical disk device of embodiment example 32... Shock detection circuit 34... Detrack / defocus detection circuit 36... Signal processing circuit 38. ... Second comparator 44 ... Third comparator 46 ... Signal processing circuit 48 ... First latch circuit 50 ... Inverter 52 ... Second Latch circuit, 54 ...... AND circuit, 56 ...... control signal, 58 ...... write-read signal.

Claims (3)

In an optical disc apparatus for recording data on an optical disc by an optical head and reproducing the recorded data,
A shock detection circuit for detecting external vibration or impact applied to the optical disc;
A detrack / defocus detection circuit for detecting at least one of detrack and defocus of the optical head;
A first latch circuit to which a detection signal from the shock detection circuit is input to a reset input terminal, and an output signal from an inverter connected to the output terminal of the first latch circuit are input to a set input terminal A second latch circuit in which an output signal of the detrack / defocus detection circuit is input to a reset input terminal; a write / read signal is detected and output to the optical head; and the shock based on external vibration or shock In a state where the output signal of the first latch circuit that has detected the output signal from the detection circuit is received, the second latch circuit receives at least the detrack and defocus of the optical head from the detrack / defocus detection circuit. When one of the output signals is detected, the recording of data on the optical disk by the optical head is interrupted. A signal processing circuit and a D circuit,
And a control circuit unit that refreshes the first latch circuit by outputting a control signal to the signal processing circuit at a constant cycle during operation of the signal processing circuit. Optical disk device.   The shock detection circuit includes an acceleration sensor for detecting external vibration or impact applied to the optical disc, and a first comparator for comparing an output signal of the acceleration sensor with a predetermined value. 1. An optical disc device according to 1. 2. The second detection circuit includes a second comparator that compares the tracking error signal with a predetermined value, and a third comparator that compares the focus error signal with a predetermined value. Optical disk device.

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