JP2724202B2 - Information recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an information recording apparatus that records information on an optical recording medium such as an optical disk.

2. Description of the Related Art Conventionally, in an information recording apparatus such as an optical disc apparatus that optically records or reproduces information on an optical recording medium such as a write-once or erasable optical disc, a semiconductor laser (light output) is used as a light source. Means) to read information on the optical disk with a relatively small continuous optical output, and to record information on the optical disk with a relatively large intermittently changing optical output of a predetermined value or more. Therefore, if the optical output is radiated to the optical disk at a predetermined value or more, even if the optical output is not intended to be recorded, indefinite information is written on the optical disk and the already recorded information is destroyed. become.

As a device for preventing the destruction of information already recorded on such an optical disk, there is one disclosed in Japanese Patent Application No. 60-100976, for example. In this method, when a pit is detected in a reproduction signal at the time of recording, it is determined that double writing is performed.

FIG. 4 shows a reflected light waveform from an optical disk in such an optical disk device. FIG. 7A shows a reflected light waveform at the time of reproduction. A relatively small light output,
There is a low-level portion (dark portion) at a position corresponding to the pit, and this becomes significant data. FIG. 4B shows a normal state.
That is, it shows a reflected light waveform when data is recorded in a non-recording area. A pulse-like waveform having a relatively large optical output corresponding to the recording data is obtained. FIG. 3C shows a 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. 4 (c) is compared with a predetermined threshold level Th, and when the presence of a pit (dark portion) is detected, it is determined that double writing is performed. That is, it is determined whether the currently recorded area is an unrecorded area or an already recorded area based on whether or not a signal corresponding to a pit is included in a reproduced signal at the time of recording.
It is designed to prevent overwriting.

However, since the reproduced signal at the time of recording becomes unstable due to the influence of, for example, undershoot of the recording beam, erroneous detection or omission of detection occurs, and there is a disadvantage that double writing cannot be prevented reliably. Was.

(Problems to be Solved by the Invention) The present invention, as described above, detects whether a recorded signal is an unrecorded area or a recorded area by using a reproduced signal at the time of recording. In order to eliminate the drawback that double writing cannot be reliably prevented due to the unstable state due to the influence of the recording beam, which caused false detection and omission of detection. And surely 2
An object of the present invention is to provide an information recording device capable of preventing overwriting.

[Structure of the Invention] (Means for Solving the Problems) An information recording apparatus according to the present invention comprises: an optical output unit for emitting a recording light beam having a high / low level to an optical recording medium based on recording data; Photoelectric conversion means for converting reflected light of the emitted recording light beam from the optical recording medium into an electric signal corresponding to the light intensity, and binarization means for binarizing the output of the photoelectric conversion means at a predetermined level When the signal binarized by the binarization unit and the recording data are input, the binarized signal and the recording light beam having the intensity level output from the light output unit are output. Detecting means for detecting the correspondence; and when the detecting means detects that the output signal of the binarizing means does not correspond to the recording light beam having the intensity level outputted from the light output means, the light Output hand Characterized in that a radiation of the recording light beam and a control unit that allowed to stop.

(Operation) According to the present invention, the magnitude of the reflected light when the recording light beam output from the optical output means is reflected from the optical recording medium is reflected from the recorded area and from the unrecorded area. In this method, double writing is detected by utilizing the characteristic that is different from the case. A recording light beam having a high / low level is emitted from an optical output means based on recording data, and the reflected light of the recording light beam from an optical recording medium is reflected. Is photoelectrically converted and binarized at a predetermined level, and the binarized signal and the recording data are input, so that the binarized signal corresponds to the intensity level of the recording light beam. If the binarized signal does not exist at the position corresponding to the recording light beam based on the detection result, it is determined that the area is a recorded area and the recording operation is performed. To stop It is a thing. As described above, since the recorded area is determined by detecting the magnitude of the reflected light of the recording light beam, which is relatively stable, stable detection can be performed, and double writing can be reliably prevented. Has become.

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

FIG. 1 shows a schematic configuration of an optical disk device as an information recording device of the present invention. In the figure, an optical disc (optical recording medium) 1 is formed by coating a metal substrate such as tellurium or bismuth in a donut shape on the surface of a substrate formed into a circular shape with, for example, glass or plastics.

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

The control circuit (control means) 3 is composed of, for example, a microcomputer or the like, and controls various controls described later in addition to the rotation control of the spindle motor 2.

An optical head 4 is provided below the optical disc 1. The optical head 4 records or reproduces information on or from the optical disk 1, and includes a semiconductor laser oscillator 5, a collimator lens 6, a polarizing beam splitter 7, an objective lens 8, a cylindrical lens 9, and a convex lens.
Well-known astigmatism optical system consisting of 10
12 and a photodetector 13 and the like. The optical head 4 is provided so as to be movable in the radial direction of the optical disk 1 by a moving mechanism (not shown) constituted by, for example, a linear motor, and is subjected to recording or reproduction in accordance with an instruction from the control unit 3. It will be moved to the target track.

The semiconductor laser oscillator (light output means) 5 generates divergent laser light (light beam) according to the drive signal S1 from the light output control circuit 14, and records information on the recording film 1a of the optical disc 1. When the information is to be recorded, a strong laser beam whose light intensity is modulated according to the information to be recorded is generated. When the information is read out from the recording film 1a of the optical disc 1 and reproduced, a weak laser beam having a constant light intensity is generated. Is caused to occur.

The divergent laser light generated from the semiconductor laser oscillator 5 is converted into a parallel light beam by the collimator lens 6 and guided to the polarization beam splitter 7. The laser beam guided to the polarization beam splitter 7 is transmitted through the polarization beam splitter 7 and is incident on the objective lens 8, where the laser light is focused toward the recording film 1 a of the optical disc 1.

The objective lens 8 is supported by a lens actuator 15 as a lens driving mechanism so as to be movable in the optical axis direction. When the laser beam is moved in the optical axis direction by the servo signal S2 from the focus servo circuit 16, the converging laser light passing through the objective lens 8 is projected on the surface of the recording film 1a of the optical disk 1, and the minimum beam The 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. The objective lens 8 is moved in a direction perpendicular to the optical axis by a servo signal from a tracking servo circuit (not shown). Has become. And
The converging laser light passing through the objective lens 8 is projected onto the surface of the recording film 1a of the optical disk 1, and is irradiated onto the recording track formed on the surface of the recording film 1a of the optical disk 1. ing. In this state, the objective lens 8 is in the combined track state. In the focused state and the focused track state, information can be written and read.

On the other hand, the divergent laser light reflected from the recording film 1a of the optical disk 1 is converted into a parallel light beam by the objective lens 8 at the time of focusing, and is returned to the polarization beam splitter 7 again. Then, the light is reflected by the polarization beam splitter 7, guided by an astigmatism optical system 11 composed of a cylindrical lens 9 and a convex lens 10 onto a four-division photodetector 12, and formed into an image in a state where the focus-shift appears as a change in shape. It is supposed to be. The quadrant photodetector (photoelectric conversion means) 12 is composed of four photodetection cells that convert light formed by the astigmatism optical system 11 into an electric signal. Two sets of signals output from two photodetector cells arranged diagonally to each other in the quadrant photodetector 12 are supplied to amplifiers 17 and 18, respectively.

The focus servo circuit 16 includes the amplifiers 17 and 18
An error amplifier 19 that performs error amplification by inputting the two signals amplified by the above, a phase correction circuit 20 that corrects the phase of an output signal of the error amplifier 19, and whether to supply an output signal of the phase correction circuit 20 to a driver 22 Analog switch to control
And a driver 22 for amplifying a signal from the analog switch 21 to drive the actuator 21. When the analog switch 21 is turned on by a focus on / off signal S3 from the control circuit 3, a signal from the phase correction circuit 20 is supplied to the actuator 15 via the driver 22 to form a focus servo loop. It has become so.

The output signals of the amplifiers 17 and 18 are supplied to an adder 23. The signal added by the adder 23 reflects the recorded contents of the optical disk 1, and is output as a waveform signal as shown in FIG.
That is, during normal recording where recording is performed in the non-recording area,
As shown in FIG. 3 (a), a signal having a signal level which is ten and several times higher than the signal level at the time of reproduction is obtained. b)
As shown in (1), a large number of signals having a signal level several times the signal level at the time of reproduction can be obtained. This is because a recording light beam is applied to a portion where a pit has already been formed, so that 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 formed of, for example, a comparator, and performs binarization by comparing an analog signal output from the adder 23 with a predetermined threshold level Th. The threshold level Th is set as a signal that is lower in level than the reflected light signal level when recording is performed on an unrecorded area and higher than the reflected light signal level when recording is performed on an already recorded area.
The reflected light signal S4 binarized by the binarization circuit 24 is supplied to the detection circuit 30.

The detection circuit (detection means) 30 receives the recording data S11 and the reflected light signal S4 output from the binarization circuit 24, and generates a recording inhibition signal S9. That is, if the optical disk 1 to be recorded is unrecorded, the recorded data
A significant signal should be obtained from the binarization circuit 24 corresponding to S11 (S10). Therefore, the detection circuit 30 checks whether or not the recording data S11 and the reflected light signal S4 from the binarization circuit 24 have a one-to-one correspondence, and a reflected light signal S4 corresponding to the recording data S11 is obtained. If not, it outputs a recording prohibition signal S9. The recording inhibit signal S9 from the detection circuit 30
Is supplied to the AND gate 33. The detection circuit 30 is supplied with a clear signal S12 from the control circuit 3 to set the inside of the detection circuit 30 to an initial state. In the initial state, the recording prohibition signal S9 is output as a high-level signal.

The AND gate 33 is connected to the control circuit 3 from an external device (not shown).
The recording data S10 supplied via the as one input,
The recording inhibition signal S9 output from the detection circuit 30 is used as the other input to output recording data S11 whose inhibition / permission is controlled. The recording data S11 is stored in the waveform shaping circuit 32.
And the detection circuit 30 described above. The waveform shaping circuit 32 shapes the recording data S11 and supplies it to the driver 28 described later.

Further, a photodetector 13 provided with a photoelectric conversion element such as a photodiode, which is provided to face the light emitting port of the semiconductor laser oscillator 5 opposite to the light emitting port of the laser beam for recording or reproduction, By irradiating the motor light from the laser oscillator 5, the monitor light is converted into an electric signal (photocurrent) and supplied to the optical output control circuit 14 as the optical 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 be kept 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 receives the optical output monitor signal S5 photoelectrically converted by the photodetector 13 and taken out as a current signal, and receives the light intensity received by the photodetector 13, that is, the semiconductor laser oscillator 5
This is converted into a voltage signal S6 corresponding to the optical output of the above and output. The voltage signal S6 output from the current / voltage conversion circuit 25 is supplied to the error amplifier 26.

The error amplifier 26 receives the voltage signal S6 as one input,
The reference voltage Vs generated by a constant voltage source (not shown) is used as the other input, the two voltages S6 and Vs are compared, and the difference is amplified and output as an error signal. The reference voltage Vs is a constant voltage for obtaining an optical output required for reproduction. By performing feedback control to bring the voltage signal S6 closer to the reference voltage Vs, a constant optical output is obtained from the semiconductor laser oscillator 5. It is supposed to be.
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, whereby an optical output for recording is output from the semiconductor laser oscillator 5. It is supposed to be.
The driver 28 has an error amplifier 26 during reproduction.
Is input, and at the time of recording, a voltage signal which is held by a sample and hold circuit (not shown) at the voltage value input at the time of the immediately preceding reproduction is input. Switching can be made depending on whether to perform recording or reproduction. In both cases of recording and reproduction, feedback control is performed at the level of the light output during reproduction.

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

First, prior to performing the recording operation, an initial operation for checking the validity of the light emission output of the semiconductor laser oscillator 5 is performed. That is, the focus on / off signal S3
, The analog switch 21 is turned off. This breaks the focus servo loop,
The objective lens 8 is released from the focusing control.
Next, a signal (not shown) for forcibly moving the lens actuator 15 is transmitted from the control circuit 3 to the driver.
It is supplied to the lens actuator 15 via 22. Thereby, the objective lens 8 is forcibly moved to the position shown by the dotted line in FIG. 1, and a defocused state is created. In this defocus state, the semiconductor laser oscillator 5 is turned on by supplying power to the light output control circuit 14, and the output of the laser beam is started. As a result, the monitor light generated from the semiconductor laser oscillator 5 is converted by the photodetector 13 into a current corresponding to the light output and output as a light output monitor signal S5. The current-voltage conversion circuit 25 converts the optical output monitor signal S5 into a voltage signal S6,
To supply. The error amplifier 26 compares the preset reference voltage Vs with the voltage signal S6, and outputs the error as an error signal. This error signal reduces the optical output of the semiconductor laser oscillator 5 when “voltage signal S6> reference signal Vs”, and increases the optical output of the semiconductor laser oscillator 5 when “voltage signal S6 <reference signal Vs”. Signal. By supplying this error signal to the driver 28, a feedback loop is formed so that the reference voltage Vs and the voltage signal S6 are controlled to be equal, whereby the optical output of the semiconductor laser oscillator 5 is kept constant.

Next, the control circuit 3 controls the actuator via the driver 22.
By driving 15, the objective lens 8 is moved in the direction of the focal point. Then, 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 the initial operation is completed. Later,
Automatic focus control is performed by a focus servo loop, and normal operations such as reading and writing of information from the optical disc 1 are performed.

In such a state, as shown in FIG. 2A, pulse-like recording data S10 is output from the control circuit 3. At this time, the recording inhibit signal output from the detection circuit 30
S9 is initially set to a high level when the clear signal S12 is supplied 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. As a result, the semiconductor laser oscillator 5 emits intermittent high-output laser light corresponding to the recording data S10. This laser light is converted into a parallel light beam by the collimator lens 6 and guided to the polarization beam splitter 7. This polarization beam splitter 7
Is transmitted through the polarizing beam splitter 7 and is incident on the objective lens 8, where the laser light is focused toward the recording film 1 a of the optical disc 1. As a result, pits are formed on the recording film 1a, and information is recorded.

On the other hand, the divergent laser light reflected from the recording film 1a of the optical disc 1 during the recording operation is converted into a parallel light beam by the objective lens 8 and returned to the polarization beam splitter 7 again. Then, the light is reflected by the polarization beam splitter 7 and is imaged on a four-division photodetector 12 by an astigmatism optical system 11 composed of a cylindrical lens 9 and a convex lens 10. At this time, if the area of the optical disc 1 on which writing is being performed is an already recorded area, reflected light waveforms having different light intensity levels are obtained as shown in FIG. 2 (b). The signal photoelectrically converted by the quadrant photodetector 12 is supplied to amplifiers 17 and 18, respectively. And amplifier 17
One of the signals amplified by and is supplied to the focus servo circuit 16 below the error amplifier 19 and used for focusing control. Further, the signal amplified by the amplifiers 17 and 18 is supplied to the other adder 23 to be added, and then supplied to the binarization circuit 24.

As shown in FIG. 3, the binarizing circuit 24 includes the adder 23
Is compared with a predetermined threshold level Th to output a binarized opposite light signal S4 as shown in FIG. 2 (c). At this time, the laser light applied to the pits already formed does not appear as significant data because the reflected light is small (the middle dotted line in FIG. 2 (c)). Then, the reflected light signal S4 is supplied to the detection circuit 30.

The detection circuit 30 includes a first flip-flop (not shown), and the first flip-flop is connected to an AND gate 3.
It is set at the rising edge of the recording data S11 (see FIG. 2 (f)) output from 3 and reset at the rising edge of the reflected light signal S4. This first
The output of the flip-flop is a double-write detection signal generated inside the detection circuit 30, as shown in FIG. 2 (d). The level of this double write detection signal is captured at the falling edge of the recording data S11, and is set in a built-in second flip-flop (not shown). And
The output of the second flip-flop becomes the write inhibit signal S9, and is set to a low level as shown in FIG. 2 (e). As a result, one input of the AND gate 33 becomes low level, and the output of the recording data S10 is suppressed. Therefore, thereafter, the recording data S11 is not output, and the waveform shaping circuit 3
2 is also suppressed, and recording on the optical disc 1 is prohibited. Then, the recording prohibition state is maintained until the clear signal S12 is output from the control circuit 3 and the second flip-flop is reset. This prevents double writing.

As described above, when it is detected that the amount of light reflected from the optical disc 1 at the time of recording is smaller than the predetermined threshold level Th, it is determined that double writing has been performed. Can be greatly reduced.

As described above, the magnitude of the reflected light from the optical disc 1 of the recording light beam having the intensity level output from the semiconductor laser oscillator 5 depends on whether it is reflected from a recorded area or from an unrecorded area. The semiconductor laser oscillator 5 emits a recording light beam having a high or low level, and the reflected light of the recording light beam from the optical disk 1 is photoelectrically converted by a four-divided photodetector 12, and the photoelectric conversion is performed. The binarized signal is binarized by a binarization circuit 24 at a predetermined threshold level smaller than the level of light reflected from the non-recorded area and higher than the level of light reflected from the recorded area. The detection circuit 30 detects whether or not the intensity level of the light beam corresponds,
When a binarized signal does not exist at a position corresponding to the recording light beam based on the detection result, the recording operation is performed by determining that the area is a recorded area and suppressing the output of the recording data S11. It is designed to stop. As described above, since the recorded area is determined by detecting the magnitude of the reflected light of the recording light beam, which is relatively stable, stable detection can be performed, and double writing can be reliably prevented. Has become.

In the above embodiment, the case where the detection circuit 30 and the like are operated using the rising and falling edges of the recording data SS11 has been described.
Recording data S10 (S11) and reflected light signal
Since the phase with S4 changes, the recording method and waveform shaping circuit
If the operation timing is appropriately changed according to the configuration of the 32, etc., the same effect as in the above embodiment can be obtained.

[Effects of the Invention] As described above in detail, according to the present invention, it is possible to provide an information recording apparatus capable of preventing erroneous detection or omission of detection and reliably preventing double writing.

[Brief description of the drawings]

1 to 3 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 timing chart for explaining the operation, FIG. 3 is a diagram for explaining the state of the reflected light at the time of normal recording and at the time of double writing, and FIG. It is a figure for explaining operation. DESCRIPTION OF SYMBOLS 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 division photodetector (photoelectric conversion means), 13 ... photodetector,
14 ... Light output control circuit, 15 ... Lens actuator, 25
... current-voltage conversion circuit, 24 ... binarization circuit (binarization means), 30 ... detection circuit (detection means), 32 ... waveform shaping circuit, 33 ... AND gate (control means).

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Akihiko Doi 70, Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside Toshiba Intelligent Technology Co., Ltd.

Claims (1)

(57) [Claims] 1. An optical output means for emitting a recording light beam having a high or low level to an optical recording medium based on recording data, and a reflection light of the recording light beam emitted from the optical output means from the optical recording medium is converted to the light. Photoelectric conversion means for converting the output of the photoelectric conversion means into a binary signal at a predetermined level; and a signal binarized by the binary conversion means and the recording. Detecting means for detecting a correspondence between the binarized signal and a recording light beam having a high / low level output by the light output means when data is input; and the binarizing means by the detecting means. Control means for stopping emission of the recording light beam from the light output means when it is detected that the output signal does not correspond to the recording light beam having the intensity level output from the light output means. Information recording apparatus characterized by the.