JPH03100924A - Optical disk recorder - Google Patents

Abstract

PURPOSE:To eliminate the necessity of time for error detection and to simplify a mechanism or control by receiving reflected light from a recorded part on a disk in an optical head at the time of recording and detecting recording error based on the light reception signal. CONSTITUTION:A recording signal a is sent through an ALPC (automatic laser power control) circuit 10 to an optical head 12 and a laser diode is driven. An optical disk 1 is irradiated with an outputted beam for recording passed through an objective lens 13, and recording is executed. The returning light reflected from the disk 1 is passed through the objective lens 13 and received by a photodetector in the optical head 12. The light reception signal is inputted through an HF amplifier 14 to a recording error detection circuit 16. By calculating difference between the light reception signal and the recording signal in an arithmetic circuit 18 in the circuit 16, a signal recorded on the disk 1 is obtained corresponding to a bit. The output is passed through a waveform shaping circuit 20 and a decoder 22 and reproducing information are obtained. Then, an error check is executed concerning the reproducing information and the error is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc recording device for recording information on an optical disc, and is capable of detecting recording errors in real time during recording.

[Conventional technology]

Conventionally, writable optical discs include DRAW (write once) discs and E-DRAW (erasable) discs. DRAW disks can be written only once, and for example, there are disks in which information pits are formed by burning out a metal recording film using heat generated by laser beam irradiation.

E-DRAW discs are rewritable.
For example, there are those that utilize magneto-optical recording and those that utilize phase change between a crystalline state and an amorphous state.

When recording information on these optical discs, recording errors may occur due to defects in the optical disc itself or dust on the substrate. Conventionally, in order to detect such errors that occur during recording, after recording is completed, a reproduction optical head is installed separately from the recording optical head (or a recording/reproduction optical head is set in the recording mode), and the reproduction beam is turned on. Error detection was performed by irradiating an optical disc with light to reproduce the recorded information.

[Problem to be solved by the invention]

According to the conventional error detection method, since the error detection is performed by reproducing the data after recording is completed, it takes time to detect the error. Furthermore, when an optical reproducing head is used separately from an optical recording head, the mechanism and control become complicated. Further, even when using a recording/reproducing optical head, switching control from a recording beam to a reproducing beam is required.

This invention solves the problems in the prior art, makes it possible to detect recording errors in real time during recording, eliminates the need for error detection time, and
The objective is to provide an optical disc recording device that can detect recording errors without complicating the mechanism or control.

[Means to solve the problem]

This invention provides a light-receiving element that receives reflected light from a recording area on a disk within the optical head during recording in which a recording beam modulated by a recording signal is irradiated from an optical head onto the disk surface. , and recording error detection means for detecting recording errors based on the light-receiving signal of the light-receiving element.

(Function) According to the present invention, during recording on an optical disc, reflected light from the recorded portion on the disc is received within the optical head, and a recording error is detected based on this received light signal. Since recording errors can be detected in real time, there is no need for time for error detection.Also, since error detection is performed using the recording beam's reflected light from the disc, it does not require complicated mechanisms or controls. It is possible to detect recording errors without causing errors.

Note that methods for detecting recording errors based on the received light signal include, for example, determining an error from the received light signal itself using an error check code in the received light signal, or determining an error by comparing the received light signal with the recorded signal. etc. is possible.

Further, as the disk reflected light for detecting recording errors, in addition to the reflected light of the recording beam, reflected light of a sub-beam irradiated to a rear position of the recording beam, etc. can be used.

〔Example〕

Examples of this invention will be described below.

(Example 1) An example of the present invention is shown in FIG. This is designed to detect errors using the reflected light of the recording beam. The recording signal is ALPC (Auto@at1c L
After the light output has been stabilized by the a5er Power Control circuit 10, it is supplied into the optical head 12 to drive the laser diode. The recording beam output from the laser diode is focused by the objective lens 13 and irradiated onto the recording surface of the optical disc 1 to perform recording.

At this time, the return light of the recording beam reflected by the optical disk 1 enters through the objective lens 13 and is received by the light receiving element in the optical head 12. This light reception signal is transmitted to the HF amplifier 14.
The signal is input to the recording error detection circuit 16 via the recording error detection circuit 16.

In the recording error detection circuit 16, the arithmetic circuit 18 calculates the difference between the received light signal and the recording signal to determine whether the optical disc 1
Obtain a signal corresponding to the pit recorded in . If the output of the arithmetic circuit 18 is of such quality that the eye pattern is sufficiently widened, the waveform shaping circuit 20 shapes the waveform into a square wave, and the decoder 22 performs digital signal processing to obtain reproduction information.

Then, an error check is performed on this reproduced information using a check code or the like, and if an error is determined, it is displayed on a display or the like and the user is notified. Furthermore, if the playback information is music information, it can be converted into an analog signal by the D/A converter 24 and supplied to the speaker 28 via the amplifier 26 for monitoring.

The operation of the apparatus shown in FIG. 1 is shown in FIG. a-d in Figure 2
indicates the signal at the position indicated by the same reference numeral in FIG. The recording signal a is, for example, an EFM signal. During recording, a reflected signal as shown by b is obtained from the optical disc 1. At this time,
On the optical disc 1, pits as shown by p are formed. The amplitude of the received light signal S is adjusted in the arithmetic circuit 18 (the amplitude is adjusted so that the height of the maximum amplitude part is the same as the amplitude of the recorded signal a), and the difference from the recorded signal a is calculated as shown by C. You can get the same signal as when playing a pit. Therefore, if this signal C is binarized by the waveform shaping circuit 20 to obtain a reproduced output d and inputted to the decoder 22, errors in the recorded bits can be determined.

That is, if pits are not recorded as in ■ due to a defect in the optical disc 1 or dust on the substrate, the received signal will be as in ■, and the output signal C of the arithmetic circuit 18 will be as in ■. Therefore, the output pulse of the waveform shaping circuit 20 is missing at that portion, and an error is determined by an error check or the like. In this way, recording errors can be determined in real time during recording.

In addition to the above error determination method, as shown in FIG.
and the exclusive OR circuit 3.
2, and the time detection circuit 34 detects that the output continues to be "1" for a predetermined period of time or more, thereby making an error determination.

In addition, as for how to use the error determination results, for example, in the case of a write-once type (DRAW disc), it is possible to judge whether the optical disc is successful or not according to the degree of opening at which the error occurs and decide whether to adopt or reject it. . For example, if a disc can record for 60 minutes, and the number of errors exceeds a predetermined number within about 10 minutes from the start of recording, there is a high possibility that the disc itself is defective.
It is possible to automatically eject the paper (it may also be possible to display a message indicating that there are many errors before ejecting the paper and request the user to make a decision). Furthermore, in the case of an E-DRAW disc, recording can be re-performed depending on the degree of opening at which an error has occurred, or if the disc itself is determined to be defective, it can be automatically ejected.

Further, the light receiving element in the optical head 12 normally uses a 4-split pin photodiode 36 as shown in FIG. When the respective sum signals e and f are determined by the HF amplifiers 38 and 40, the rising and falling edges of these signals e and f at the time of pit formation are shifted in time as shown in FIG. Therefore, when both signals e and f are added by the HF amplifier 42, the output g produces jitter as shown in FIG.
(portions indicated by thick lines), detection errors are likely to occur.

To prevent this, it is sufficient to use one of the signals e and f without adding them together.

Furthermore, as a method for obtaining the reproduced output d corresponding to the pits from the received light signal, in addition to using the arithmetic circuit 18 shown in FIG. 1, the configuration shown in FIG. 6 can also be used. In the circuit shown in FIG. 6, the light reception signal outputted from the HF amplifier 14 is input to the comparator 44, where predetermined reference levels Vl and V are input.
2 (Vl > V2), the flip-flop circuit 46 is set at the falling edge where the received light signal falls below the reference level Vl, and the flip-flop circuit 46 is set at the rising edge where the received light signal becomes higher than the reference level V2. Reset. FIG. 7 shows the operation of the circuit shown in FIG. 6. By adjusting the reference levels Vl and V2, a signal d corresponding to a pit can be obtained.

As shown in FIG. 8, the recording beam is irradiated by dividing the recording signal a into multiple pulses within the time required to form one pit, thereby preventing heat from accumulating in the disk. , accurately define the positions of the leading edge and trailing edge of the bit to reduce jitter and S/N of the reproduced signal.
There is a method that aims to improve the
07372 specification), when this method is used, as shown in the figure, the light reception signal is interrupted within the time to form one pit, so that the arithmetic circuit 18 of FIG. 1 and the arithmetic circuit 18 of FIG. With this circuit, it is not possible to obtain a playback output that corresponds to the pits.

Therefore, as shown in FIG.
The signal is compared with a predetermined reference level v8 to be binarized, and the falling edge thereof triggers the little gable one-shot multivibrator 50.

Further, the comparator 52 sets the received light signal to a predetermined reference level v4.
This is then input to the AND circuit 54 along with the original signal, and the one-shot multivibrator 56 is triggered at the rise of the output of the AND circuit 54 to create a reset pulse. Reset the shot multivibrator 50 (see FIG. 8). As a result, the reproduction output d corresponding to the pit can be obtained from the little gable φ one-shot multivibrator 50. The length of the one-shot pulse of the little gable φ one-shot multivibrator 50 is longer than the maximum pulse division interval and the minimum inversion interval of the original signal (C
For D format, it should be 3T) or less.

(Example 2) Another example of the present invention is shown in FIG. This uses sub-beams to reproduce recorded information. After the recording signal a is stabilized in optical output by the ALPC circuit 10, it is supplied into the optical head 12' to drive the laser diode. The generated laser beam is divided into a main beam and sub beams by a diffraction grating. Both of these beams are irradiated onto the recording surface of the optical disc 1 via the objective lens 13. Figure 11 shows the irradiation state of the main beam M and sub-beam St on the disk.
Illuminated along the track. Recording is performed using the main beam M. Also, here, an example is shown in which a three-beam method tracking control optical head is used, and there are two sub-beams S1 and S2, but the recorded information is reproduced using the rear sub-beam St with respect to the recording direction. (sub-beam S2 is not required). In addition, sub-beam S
For t and S2, a diffraction grating or the like is designed so that the power does not affect the recording film. Further, since the sub-beams S1 and S2 for three-beam tracking control are originally shifted left and right from the track center line, the diffraction grating is adjusted so that the sub-beam S2 is on the track center line. Furthermore, since the sub-beam Sl is used for information reproduction in this way, tracking control uses the Bou-Soucheple method using the main beam M.

The return light of the sub-beam Sl reflected by the optical disk 1 enters through the objective lens 13 and is received by a light-receiving element for the sub-beam Sl in the optical head 12'. Further, the return light of the main beam M enters from the objective lens 13 and is received by the four-split light receiving element for the main beam Sl in the optical head 12', and focus control and tracking control are executed, and the IF amplifier 14 is output via

The light reception signal of the light receiving element for sub-beam Sl is sent to the arithmetic circuit 18 in the recording error detection circuit 19 via the HF amplifier 15.
is input. Further, the recording signal a is manually input to the arithmetic circuit 18 via the amplifier 17. Further, the arithmetic circuit 18 obtains a reproduction signal corresponding to the pit by taking the difference between the recording signal a and the sub-beam reception signal S.

FIG. 12 shows the operation of the circuit of FIG. 10.

a is a recording signal, PO is a pit recorded by the main beam M, and pt is a pit reproduced by the sub beam St.

Pi is -1/vt (N: main beam M
The distance between the spot caused by the sub-beam Sl and the spot caused by the sub-beam Sl, vL (two-linear velocity), is generated with a delay. b
C is the waveform reproduced by the return light of the sub-beam St, and C is the waveform after calculation by the calculation circuit 18. This reproduced waveform C is
It is obtained by subtracting the recording signal a whose gain has been adjusted by the amplifier 17 from the received light signal. According to this method, since there is no recording jitter (variation in the time at which pits start to be formed) compared to the method of the first embodiment, the reproduced signal C has a high-quality waveform with low jitter.

〔Effect of the invention〕

As explained above, according to the present invention, when recording on an optical disc, the reflected light from the recording area on the disc is received within the optical head, and recording errors are detected based on this received light signal. Recording errors can be detected in real time, eliminating the need for time for error detection. Further, since error detection is performed using the disk reflected light of the recording beam, recording errors can be detected without complicating the mechanism or control.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a waveform diagram showing an example of the operation of the device shown in FIG. FIG. 3 is a circuit diagram showing a specific example of error determination. FIG. 4 is a block diagram showing an example of a circuit configuration for obtaining a light-receiving signal when a four-part P1n photodiode is used as a light-receiving element. FIG. 5 is a waveform diagram showing the operation of the circuit of FIG. 4. FIG. 6 is a block diagram showing an example of a circuit configuration for obtaining a signal corresponding to a pit based on a received light signal. FIG. 7 is a waveform diagram showing the operation of the circuit of FIG. 6. FIG. 8 is a waveform diagram showing the operation of the circuit of FIG. 9. FIG. 9 is a block diagram showing an example of a circuit configuration for obtaining a signal corresponding to a pit based on a received light signal. FIG. 10 is a block diagram showing another embodiment of the invention. FIG. 11 is a plan view showing an example of the arrangement of disk beam spots emitted from the optical head 12' of FIG. 10. FIG. 12 is a waveform diagram showing the operation of the device of FIG. 10. 1... Optical disk, 12.12'... Optical head, 1
6.19... Recording error detection circuit, 18... Arithmetic circuit, 36... 4-division P1n photodiode (light receiving element), M... Main beam, Sl... Sub beam.

Claims (3)

[Claims] (1) A light-receiving element that receives reflected light from a recording portion on the disk within the optical head during recording in which a recording beam modulated by a recording signal is irradiated from the optical head onto the disk surface; An optical disc recording apparatus comprising a recording error detection means for detecting a recording error based on a light reception signal of the light receiving element. (2) The optical disc recording apparatus according to claim 1, wherein the recording error detection means detects a recording error by calculating the recording signal and the light reception signal. (3) The optical disk recording apparatus according to claim 1 or 2, wherein the reflected light is disk reflected light of the recording beam.