JPH03116536A - Optical disk device - Google Patents

Abstract

PURPOSE:To reduce a double writing area and to suppress the lowering reliability of recording data by executing peak detection for the reflected light peak position of a pulse-shaped recording light from an optical disk, comparing the reflected light at the peak position with a prescribed level and stopping recording operation when a counted value for the number of pulses less than the prescribed level is more than a prescribed value. CONSTITUTION:Double writing is detected by utilizing a property that the intensities of the reflected beams of the pulse-shaped recording beams are different from each other in a case that the light is reflected from a recorded area and a case that it is reflected from an unrecorded area. Namely, the pulse-shaped recording light is radiated from a light output means 5 and the peak position of the reflected light is detected. At the peak position, the reflected light of the pulse-shaped recording light is compared with the prescribed level. The reflected light less the prescribed level is detected and the number of pulses in the reflected light less than the prescribed level is counted by a counting means 31. When the counted value is more than the prescribed value, it is judged that the area is the recorded area, and the recording operation is stopped. Thus, the double writing area is reduced as much as possible and the reliability of the data can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an optical disc device for recording and reproducing information on and from an optical recording medium such as an optical disc.

(Prior Art) Conventionally, in an optical disk device such as an optical disk device that optically records or reproduces information on an optical recording medium such as a write-once type or erasable type optical disk, a semiconductor laser (light output means) is used as a light source. ), the information on the optical disk is read with a relatively small continuous optical output, while information is recorded on the optical disk with an intermittently changing optical output of a relatively large predetermined value or more. Therefore, if an optical disc is irradiated with a light output that exceeds the above-mentioned predetermined value, even if it is not intended to be recorded, undefined information will be written on the optical disc, destroying information that has already been recorded. become.

For example, Japanese Patent Application No. 10097/1983 discloses methods for preventing the destruction of information already recorded on such optical discs.
There are some disclosed in 6.

This method determines that double writing has occurred when a bit is detected in the reproduced signal during recording.

FIG. 6 shows a waveform of light reflected from an optical disc in such an optical disc device. FIG. 4(a) shows a reflected light waveform during reproduction. A relatively small optical output is obtained, and a low-level part (dark part) exists at a position corresponding to a bit, and this becomes significant data. FIG. 5B shows a reflected light waveform in a normal state, that is, when data is recorded in a non-recording area.

A pulse-like waveform with a relatively large optical output corresponding to the recorded data can be obtained. Furthermore, the same figure (C) shows the reflected light waveform at the time of double writing. A waveform is obtained in which the reflected light waveform during reproduction and the reflected light waveform during normal recording are superimposed. Then, the reflected light waveform shown in FIG. 6(c) is compared with a predetermined threshold level Th, and when the presence of a bit (dark area) is detected, it is determined that double writing has occurred. In other words,
Depending on whether the playback signal during recording contains a signal corresponding to the bit, it is determined whether the area currently being recorded is an unrecorded area or a recorded area, and double writing is prevented. It is supposed to be done.

However, the playback signal during recording becomes unstable due to the influence of, for example, undershoot of the recording beam, resulting in false detection or omission of detection, which has the disadvantage that double writing cannot be reliably prevented. Ta. On the other hand, in order to reliably detect double writing, there is a method that detects double writing while allowing double writing within the range of correction ability, but this method This has the disadvantage that the reliability of the recorded data is impaired because the data remain.

(Problems to be Solved by the Invention) As described above, the present invention detects whether the area is an unrecorded area or a recorded area using a reproduction signal during recording. The disadvantage is that it is not possible to reliably prevent double writing due to the unstable state due to the influence of the recording beam, resulting in false detection or omission of detection. This was done in order to eliminate the drawback that the reliability of recorded data is impaired because double written areas remain in systems that attempt to detect writing reliably. An object of the present invention is to provide an optical disc device that can reliably prevent double writing and improve data reliability by minimizing double writing areas.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, an optical disk device of the present invention includes a light output means for emitting a pulsed recording light beam and a light emitted from the light output means. a first detection means for detecting a peak position of the reflected light of the recording light beam emitted from the light output means; and a first detection means for detecting the peak position of the reflected light of the recording light beam emitted from the light output means at the peak position detected by the first detection means. a second detection means for counting the number of pulses in which the reflected light detected by the second detection means is below a predetermined level; and when the counting means counts a predetermined value;
It is characterized by comprising a control means for stopping emission of the recording light beam from the light output means.

(Function) The present invention is characterized in that the magnitude of the reflected light of the pulsed recording light beam output from the optical output means is different depending on whether it is reflected from a recorded area or from an unrecorded area. The device detects double writing using the optical output means, emits a pulsed recording light beam from the optical output means, detects the peak position of the reflected light of this pulsed recording light beam, and at this peak position the pulsed recording light beam is detected. By comparing the reflected light of the recording light beam with a predetermined level, the reflected light below a predetermined level is detected, and the number of pulses of the reflected light below the predetermined level is counted by a counting means, and the counted value is determined as a predetermined value. When this happens, the area is determined to be a recorded area and the recording operation is stopped. In this way, since the magnitude of the reflected light of the recording light beam is detected, which is relatively stable, stable detection is possible, and double writing is determined after detecting multiple reflected lights below a predetermined level. This makes it possible to reliably prevent double writing. In addition, since it is compared with a predetermined level only at the detected peak position regardless of the magnitude of the peak value of the reflected light, there is no need to consider reflected light below the predetermined level in areas where no peak position appears, and therefore Since the count value by the counting means can be set small, it is possible to reduce the double write area that occurs due to double write detection, and it is possible to prevent a decrease in the reliability of recorded data.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of an optical disc device as an information recording device of the present invention. In the figure, an optical disk (optical recording medium) 1 is formed by coating a metal film layer of tellurium, bismuth, or the like in a donut shape on the surface of a circularly molded substrate made of, for example, glass or plastic.

The optical disc 1 is rotated by a spindle motor 2. This spindle motor 2 is
A motor control circuit (not shown) that operates in response to a control signal from the control circuit 3 controls the start and stop of rotation, the number of rotations, and the like.

The control circuit 3 is composed of, for example, random logic, and includes circuits for controlling the rotation of the spindle motor 2 as well as various other controls to be described later.

An optical head 4 is disposed below the optical disc 1 . This optical head 4 records or reproduces information on the optical disc 1, and includes a semiconductor laser oscillator 5, a collimator lens 6, and a polarizing beam splitter 7.
, objective lens 8, cylindrical lens 9 and convex lens 1
The astigmatism optical system includes a well-known astigmatism optical system 11, a 4-split photodetector 12, a photodetector 13, and the like. The optical disc 4 is arranged to be movable in the radial direction of the optical disc 1 by a moving mechanism (not shown) constituted by, for example, a linear motor, and is configured to record or reproduce data according to instructions from the control unit 3. It is now possible to move to the target track.

The semiconductor laser oscillator 5 generates a diverging laser beam (light beam) according to the drive signal S1 from the optical output control circuit 14, and records information M1 on the optical disc 1.
To record on the optical disc 1, a strong laser beam whose optical intensity is modulated according to the information to be recorded is generated, and when information is read and reproduced from the recording film 1a of the optical disc 1, the laser beam has a constant optical intensity. It is designed to generate weak laser light.

The diverging laser beam generated by the semiconductor laser oscillator 5 is converted into a parallel beam by a collimator lens 6 and guided to a polarized beam splitter. The laser beam guided by the polarized beam splitter passes through the polarized beam splitter 7 and enters the objective lens 8, and is focused by the objective lens 8 toward the recording film 1a of the optical disc 1.

The objective lens 8 is supported movably in the forward axis direction by a lens actuator 15 as a lens drive mechanism. The focused laser beam is moved in the direction of the light beam 11h by the servo signal S2 from the focus servo circuit 16, so that the focused laser beam that has passed through the objective lens 8 is projected onto the surface of the recording film 1a of the optical disc 1, and the minimum beam A spot is formed on the surface of the recording film 1a of the optical disc 1. In this state, the objective lens 8 is in a focused state.

The objective lens 8 is also movable in a direction perpendicular to the optical axis, and is moved in the direction perpendicular to the optical axis by a servo signal from a tracking servo circuit (not shown). It has become. Then, the focused laser beam that has passed through the objective lens 8 is projected onto the surface of the recording film 1a of the optical disc 1, and is irradiated onto the recording tracks formed on the surface of the recording film 1a of the optical disc 1. It has become. In this state, the objective lens 8 is in a matching track state. In the focused point and focused track state, information can be written and read.

On the other hand, the diverging laser beam reflected from the recording film 1a of the optical disk 1 is converted into a parallel beam by the objective lens 8 when it is focused, and is returned to the polarized beam splitter again. The beam is then reflected by the polarizing beam splitter 7 and guided onto the 4-split photodetector 12 by the astigmatism optical system 1 consisting of a cylindrical lens 9 and a convex lens 10, where it is focused with a focus shift appearing as a change in shape. It is now being imaged. The four-split photodetector 12 is composed of four photodetection cells that convert the light imaged by the astigmatism optical system 11 into electrical signals.

Two sets of signals output from two photodetection cells arranged diagonally with each other in this four-split photodetector 12 are supplied to amplifiers 17 and 18, respectively.

The focus servo circuit 16 includes an error amplifier 19 that inputs the two signals amplified by the amplifiers 17 and 18 and performs error amplification, a phase correction circuit 20 that corrects the phase of the output signal of the error amplifier 19, and a phase correction circuit 20 that corrects the phase of the output signal of the error amplifier 19. An analog switch 21 that controls whether or not to supply the output signal of the circuit 20 to the driver 22, and a driver 2 that amplifies the signal from the analog switch 21 and drives the actuator 21.
2. When this analog switch 21 is turned on by the focus on/off signal S3 from the control circuit 3, a focus servo loop is formed by supplying the signal from the phase correction circuit 20 to the actuator 15 via the driver 22. It has become so.

Further, the output signals from the amplifiers 17 and 18 are supplied to an adder 23. The signal added by the adder 23 reflects the recorded content of the optical disc 1, and is output as a waveform signal as shown in FIG. In other words, during normal recording in a non-recorded area, a signal with a signal level ten times higher than the signal level during playback is obtained, as shown in FIG. When performing so-called double writing, the fifth
As shown in Figure (b), many signals having a signal level several times higher than the signal level during reproduction can be obtained. this is,
This is because the recording destination beam is irradiated onto a portion where pits have already been formed, so the amount of reflected light is reduced at the pit portion. The output signal of the adder 23 having such a waveform is sent to the binarization circuit 24.

The binarization circuit 24 is composed of, for example, a comparator, and performs binarization by comparing the analog signal output from the adder 23 with a predetermined threshold level Th. This threshold level Th is set as a signal that is lower than the level of the reflected light signal when recording is performed on an unrecorded area, and higher than the level of the reflected light signal when recorded on an already recorded area. The reflected light signal S binarized by this binarization circuit 24
4 is supplied to the detection circuit 30.

The peak detection circuit 35 is constituted by a circuit as shown in FIG. 2, for example. In the figure, 35a is a comparator, R, R2 are resistors, D, D2 are diodes, and CI is a capacitor. The output of the adder 23 is supplied to the non-inverting input terminal (+) of the comparator 35a via a resistor R3. In addition, the comparator 35a
A resistor R1 and a capacitor C are connected to the inverting input terminal (-) of
A voltage is supplied from a time constant circuit configured by 1.

The peak detection circuit 35 performs binarization at the peak position of the analog signal output by the adder 23. In other words, the peak value is detected by an autoslice circuit and binarized.

That is, the non-inverting input terminal (+) of the comparator 35a
The signal input to the input terminal (signal at point A) is the output signal of the adder 23 as it is, but the signal input to the inverting input terminal (-) (signal at point B) is equal to the voltage drop of the diode DI+D2. Since the input is delayed by the time constants R and C, the output of the comparator 35a changes when the input changes from rising to falling or from falling to rising, as shown in Figure 3. . Therefore, with the above configuration, the peak value of the output signal of the adder 23 is detected. According to this peak detection circuit 35, even if the peak height changes, binarization can be performed at the peak position. Peak detection signal S13 output by this peak detection circuit 35
is supplied to a detection circuit 30 and a counter circuit 31.

The detection circuit 30 manually inputs the peak detection signal 313 and the reflected light signal S4 output from the binarization circuit 24 to generate a double writing detection signal S8. That is, if the optical disc 1 to be recorded is unrecorded, a significant signal should be obtained from the binarization circuit 24 in response to the peak detection signal 813. Therefore, the detection circuit 30 checks whether the peak detection signal 813 and the reflected light signal S4 from the binarization circuit 24 have a one-to-one correspondence, and the reflected light signal S4 corresponding to the peak detection signal S13 is If the double writing detection signal S8 is not obtained, a double writing detection signal S8 is output. The double writing detection signal S8 from this detection circuit 30 is supplied to a counter circuit 31.

The counter circuit 31 counts the number of occurrences of the double write detection signal S8 outputted by the detection circuit 30, and outputs a recording prohibition signal S9 when the number exceeds a predetermined value. When it is detected that the value exceeds a predetermined value, a recording prohibition signal S9 is generated.
The reason for this is that if there is a part of the optical disc 1 where the reflective film is missing from the beginning, such as a pinhole, the double writing detection signal S8 will be output even if it is an unrecorded area, which may cause an error. This is because it will result in detection. The above predetermined value is determined as follows. In other words, the upper limit of the predetermined value is regulated by the burst error correction capability of the device. This is because recording must be stopped before data destroyed by double writing can be repaired by an error correction circuit (not shown). On the other hand, it is determined by the frequency of malfunctions of the detection circuit 30 due to noise or the like.

The double writing detection signal S8 is output, but if the recording prohibition signal S9 is output before passing through the defective part, a false detection will occur, so the predetermined value must be at least the minimum allowable value. Must be.

The recording prohibition signal S9 from this counter circuit 31 is AND
It is supplied to the gate 33. Note that the counter circuit 31 is supplied with a clear signal S12 from the control circuit 3 to reset the counter.

The AND gate 33 receives the recording data S10 supplied from an external device (not shown) via the control circuit 3 as one input, and receives the recording prohibition signal S9 outputted from the counter circuit 31.
is used as the other input to output recording data Sll whose prohibition/permission is controlled. This recording data S11 is supplied to a waveform shaping circuit 32. The waveform shaping circuit 32 shapes the recording data Sll and supplies it to a driver 28, which will be described later.

In addition, the photodetector 13 constituted by a charging conversion element such as a photodiode, which is provided facing the light emitting port opposite to the light emitting port for recording or reproducing laser light of the semiconductor laser oscillator 5, When the monitor light from the laser oscillator 5 is irradiated, the monitor light is converted into an electric signal (photocurrent) and supplied to the light output control circuit 14 as the light output monitor signal S5 of the semiconductor laser oscillator 5. ing.

The optical output control circuit 14 controls the optical output of the semiconductor laser oscillator 5 to keep it constant by inputting the optical output monitor signal S5 output from the semiconductor laser oscillator 5 and performing feedback control. That is, the current-voltage conversion circuit 25 inputs the optical output monitor signal S5 photoelectrically converted by the photodetector 13 and extracted as a current signal, and converts the light intensity received by the photodetector 13, that is, the light of the semiconductor laser oscillator 5. It converts into a voltage signal S6 according to the output and outputs it. A voltage signal S6 outputted from this current-voltage conversion circuit 25 is supplied to an error amplifier 26.

The error amplifier 26 uses the voltage signal S6 as one input and a reference voltage Vs generated by a constant voltage source (not shown) as the other input, compares the two voltages S6 and Vs, amplifies the difference, and calculates the error. It is output as a signal. The reference voltage Vs is a constant voltage for obtaining the optical output necessary for reproduction, and the voltage signal S6 is converted to the reference voltage Vs.
By feedback control to bring it closer to
A constant optical output can be obtained from the semiconductor laser oscillator 5. The error signal from the error amplifier 26 is supplied to a driver 28.

The driver 28 is supplied with a recording pulse signal S7 corresponding to the information to be recorded from the above-mentioned waveform shaping circuit 32, so that the optical output for recording is output from the semiconductor laser oscillator 5. It is now possible to do so. Note that the voltage signal output from the error amplifier 26 is input to the driver 28 during reproduction, and the voltage signal output from the error amplifier 26 is input to the driver 28 during recording.
A voltage signal is input in which the voltage value input during the previous playback is held in a sample-and-hold circuit (not shown), and these two inputs can be switched depending on whether recording or playback is being performed. It has become. In both recording and reproduction, feedback control is performed based on the level of optical output during reproduction.

Next, the operation of suppressing double writing during recording in the optical disc device configured as described above will be explained with reference to the timing chart of FIG. 4.

First, before performing a recording operation, an initial operation is performed to check the validity of the light emission output of the semiconductor laser oscillator 5. In other words, the focus on/off signal S from the control circuit 3
By outputting 3, the analog switch 21 is turned off. As a result, the focus servo loop is disconnected, and the objective lens 8 is released from the force shifting control. Next, at 0, a signal (not shown) for forcibly moving the lens actuator 15 is supplied from the control circuit 3 to the lens actuator 15 via the force driver 22 . As a result, the objective lens 8 is forcibly moved once to the position shown by the dotted line in FIG. 1, creating a defocused state. In this defocused state, the optical output control circuit 1
By supplying power to 4, the semiconductor laser oscillator 5
is turned on and laser beam output begins. As a result, the monitor light generated from the semiconductor laser oscillator 5 is converted into a current according to the light output by the photodetector 13 and output as a light output monitor signal S5. The current-voltage conversion circuit 25 converts this optical output monitor signal S5 into a voltage signal S6 and supplies it to the error amplifier 26.

In the error amplifier 26, a preset reference voltage Vs
and the voltage signal S6, and output the error amount as an error signal. This error signal is a signal that "reduces the optical output of the semiconductor laser oscillator 5 if voltage signal S6 > reference signal VsJ, and increases the optical output of semiconductor laser oscillator 5 if voltage signal S6 > reference signal VsJ". By supplying this error signal to the driver 28, a feedback loop is formed and the reference voltage Vs and the voltage signal S6 are
The optical output of the semiconductor laser oscillator 5 is thereby kept constant.

Next, the control circuit 3 drives the actuator 15 via the driver 22 to move the objective lens 8 toward the in-focus position. When it is determined that the in-focus position has been reached, the analog switch 21 is turned on to connect the focus servo loop and complete the initial operation. Thereafter, automatic focus control is performed by a focus servo loop, and normal operations such as reading and writing information from the optical disc 1 are performed.

In such a state, as shown in FIG. 4(a),
The control circuit 3 outputs pulsed recording data 510. At this time, the recording inhibit signal S9 output from the counter circuit 31 is initially set to a high level by supplying the clear signal S12 from the control circuit 3. Therefore, the recording data S10 is supplied to the waveform shaping circuit 32 via the AND gate 33, and further supplied to the driver 28. As a result, the semiconductor laser oscillator 5 emits intermittent high-output laser light according to the recording data SIO. This laser light is converted into a parallel beam by a collimator lens 6 and guided to a polarizing beam splitter 7. The laser beam guided to the polarizing beam splitter 7 passes through the polarizing beam splitter 7 and enters the objective lens 8.
The objective lens 8 focuses the light toward the recording film 1a of the previous disk 1. As a result, pits are formed on the recording film la, and information is recorded.

On the other hand, the diverging laser beam reflected from the recording film 1a of the optical disk 1 during the recording operation is converted into a parallel beam by the objective lens 8, and returned to the polarized beam splitter again. Then, it is reflected by this polarizing beam splitter 7 and imaged onto a four-split photodetector 12 by an astigmatism optical system 11 consisting of a cylindrical lens 9 and a convex lens 10 . At this time, if the area of the optical disc 1 to which writing is being performed is an area that has already been recorded, as shown in FIG. 4(b).
As shown in the figure, reflected light waveforms with different light intensity levels are obtained. Signals photoelectrically converted by this four-split photodetector 12 are supplied to amplifiers 17 and 18, respectively. Then, one of the signals amplified by the amplifiers 17 and 18 is supplied to the focus servo circuit 16 below the error amplifier 19,
Used for force control. In addition, the amplifier 17
The other of the signals amplified in and 18 is supplied to an adder 23 for addition, and then supplied to a binarization circuit 24.

As shown in FIG. 5, the binarization circuit 24 includes the adder 2
By comparing the signal from 3 with a predetermined threshold level Th, a binarized reflected light signal S4 as shown in FIG. 4(e) is output. At this time, the laser light irradiated onto the pits that have already been formed does not appear as significant data because the reflected light is small (Figure 4 (C
) middle dotted line part). This reflected light signal S4 is then supplied to the detection circuit 30 and the peak detection circuit 35.

As described above, the peak detection circuit 35 detects and binarizes the peak value of the analog signal output by the adder 23,
This is supplied to the detection circuit 30 as a peak detection signal 313. On the other hand, the detection circuit 30 includes a flip-flop (not shown), which is set at the falling edge of the peak detection signal 813 output from the peak detection circuit 35 and set at the rising edge of the reflected light signal S4. It is reset by . The output of this flip-flop is output from the detection circuit 30 as a double write detection signal S8, as shown in FIG. 4(e).

The counter circuit 31 inputs the double writing detection signal S8 manually, captures the level of the double writing detection signal S8 at the rising edge of the other input, the peak detection signal S13, and outputs a count pulse of a built-in counter (not shown). (4th
(see figure (f)). This count pulse is counted by a counter, and when a predetermined value is counted, a recording prohibition signal S
Make 9 a low level. As a result, the human power on one side of the AND gate 33 becomes low level, and the output of the recording data S10 is suppressed. Therefore, from then on, the recording data Sll is not output, the output S7 of the waveform shaping circuit 32 is also suppressed, and recording on the optical disc 1 is prohibited. The recording prohibited state will be maintained until the clear signal S12 from the control circuit 3 is output. This prevents double writing.

In this way, instead of immediately determining that double writing is occurring when a small amount of reflected light from the optical disc 1 is detected, it is determined that double writing is occurring when a predetermined number or more of small amounts of reflected light are detected. This makes it possible to significantly reduce false positives and missed positives.

Furthermore, until a predetermined number or more of small reflected light beams from the optical disc 1 are detected, the data in the low recording area will be destroyed, but the amount of data destroyed is set so that it is within the error correctable range. The reliability of the recorded data is not compromised.

Furthermore, according to this method, since the detection circuit 300 is both set and reset by the signals S13 and S4 created from the reflected light waveform (see FIG. 4(b)), defects such as pinholes, etc. If an attempt is made to record in a place where there is no reflective film at all, no double writing detection signal S8 will be output from the detection circuit 30 because no reflection film will appear at all.

Therefore, the count value of the counter circuit 31 should be set to a value that prevents the recording inhibit signal S9 from being output due to malfunction of the detection circuit 30 due to noise etc. (However, since it is possible to set a relatively small value, It has the advantage that only a small amount of data is required.

As described above, when the pulsed recording light beam output from the semiconductor laser oscillator 5 is reflected by the optical disc 1, the magnitude of the reflected light differs between when it is reflected from an already recorded area and when it is reflected from an unrecorded area. Utilizing the property that the pulsed recording destination beam is different when reflected from the optical disc 1, the semiconductor laser oscillator 5 emits a pulsed recording destination beam, and the peak detection circuit 35 detects the peak position of the reflected light when this recording light beam is reflected by the optical disk 1. The reflected light is compared with a predetermined threshold level at this peak position to be binarized, and the detection circuit 30 detects a pulse below the threshold level from this binarized signal. Counter circuit 3 calculates the number of pulses.
1, and when the counted value exceeds a predetermined value, it is determined that the area is a recorded area and the recording operation is stopped, so the reflection of the recording light beam is relatively stable. The size of the light is detected, allowing stable detection, and double writing is determined after detecting multiple reflected lights below the threshold level, so double writing can be reliably prevented. It becomes. In addition, since it is compared with the threshold level only at the peak position detected regardless of the magnitude of the peak value of the reflected light, there is no need to consider reflected light below the threshold level in areas where no peak position appears.
Therefore, since the count value by the counter circuit 31 can be set small, the double writing area that occurs due to double writing detection can be made smaller, and a decrease in the reliability of recorded data can be prevented. It becomes.

In the above embodiment, a case has been described in which the detection circuit 30, the counter circuit 31, etc. are operated using the falling edge of the peak detection signal 313 and the falling edge of the binarized reflected light signal S4. Since the phase of the peak detection signal S13 and the reflected light signal S4 changes depending on the method of recording, the configuration of the waveform shaping circuit 32, etc., in this case, the operation timing is changed as appropriate depending on the recording method, the configuration of the waveform shaping circuit 32, etc. If configured to do so, the same effects as in the above embodiment can be achieved.

[Effects of the Invention] As detailed above, according to the present invention, double writing can be reliably prevented by preventing false positives and false positives, and data reliability can be improved by minimizing double writing areas. It is possible to provide an optical disc device that can be improved.

[Brief explanation of drawings]

1 to 5 show an embodiment of the present invention,
FIG. 1 is a block diagram showing a schematic configuration of an optical disk device.
Fig. 2 is a circuit diagram showing the configuration of the peak detection circuit, Fig. 3 is a diagram showing the operation of the peak detection circuit, Fig. 4 is a timing chart to explain the operation, and Fig. 5 is a diagram showing normal recording and duplex recording. It is a diagram for explaining the state of reflected light during writing,
FIG. 6 is a diagram for explaining the conventional double writing prevention operation. 1... Optical disk, 2... Spindle motor, 3.
...Control circuit (control means) 4...Optical head, 5.
... Semiconductor laser oscillator (light output means), 8... Objective lens, 12... 4-split photodetector, 13... Photodetector, 14... Light output control circuit, 15... Lens Actuator, 25... Current-voltage conversion circuit, 24... Binarization circuit (generating means) 30... Detection circuit (second detection means) 31... Counter circuit (counting means), 32
... Waveform shaping circuit, 33... AND gate (control means), 35... Peak detection circuit (first detection means),
35a... Comparator.

Claims (1)

[Scope of Claims] A light output means for emitting a pulsed recording light beam; a first detection means for detecting a peak position of reflected light of the recording light beam emitted from the light output means; a second detection means for detecting the reflected light of the recording light beam emitted from the optical output means at the peak position detected by the detection means; An optical disc apparatus comprising: a counting means for counting the number of pulses that is below a level; and a control means for stopping emission of the recording light beam from the optical output means when the counting means has counted a predetermined value. .