JPH02301019A - Optical recorder - Google Patents

Abstract

PURPOSE:To accelerate processing speed when write is performed by easily detecting a flaw simultaneously with the write by performing the detection of the flaw and checking by using a beam obtained by separating from the same light source as that for a write beam. CONSTITUTION:Emission light from a laser diode 1 is separated to the write beam 4, a preceding beam 5, and a succeeding beam via, for example, a diffraction grating, and the recording layer of an optical card is irradiated with the beams. A pit 8 is formed sequentially on the recording layer with a recording signal A, and reflected light beam from the recording layer of the beam 5 is detected at a photodetector 10, and is amplified 14, and is inputted to an AGC circuit 18 as a detection signal B. A subtraction processing is applied on a part synchronizing with the edges of the output signal B and the recording signal A by a share of signal synchronized with the signal A, and it goes to a differential waveform corresponding to the response speed of a device comprising the AGC circuit 18, and only the waveform of the flaw 23 is left on an output signal C from the circuit. The output signal C is inputted to a flaw detection circuit 22, and the differential waveform is eliminated from it, and only the waveform of the flaw 23 is outputted, which easily detects the presence/ absence of the flaw.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial Application Field> The present invention relates to an optical recording device that records information by irradiating a writing beam onto an optical recording medium.

<Prior Art> Conventionally, there are various devices for optically recording and reproducing information using optical cards, optical discs, and the like as optical recording media. By the way, since information is recorded on optical recording media at a high density, defects are likely to occur even due to small external factors during recording, so it is necessary to confirm that there are no defects in the recorded information. be. For example, JP-A-63-24
Publication No. 9939 discloses that, at the time of writing, the reflected light from the recording surface of the preceding beam that precedes the writing beam is compared with the reflected light of the writing beam, so that only the reproduced signal due to the pits formed as the recorded signal is extracted. A method is disclosed in which it is possible to determine the presence or absence of defects in recorded information.

However, although the above-mentioned device can determine whether there are defects in the recorded information, it is not only impossible to easily detect scratches between pits, especially when there are scratches on the recording surface. Since pits formed by the writing beam are not reproduced by a beam other than the writing beam, there is a problem in that defects in the recording layer cannot be reliably detected.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main purpose of the present invention is to solve the following problems when optically recording information on an optical recording medium:
An object of the present invention is to provide an optical recording device that can reliably detect the presence or absence of scratches on a recording layer and the presence or absence of defects in recorded information.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, the present invention provides an optical system for recording information on an optical recording medium using a writing beam that changes according to a recording signal. a recording device, comprising: means for generating a leading beam separated from the same light source as the writing beam by a smaller level than the writing beam and preceding the writing beam in the information recording direction; and the optical system of the leading beam. means for detecting reflected light from an optical recording medium; and a signal that changes in synchronization with the recording signal from a detection signal by the detection means in order to detect a defect in the optical recording medium before recording the information. An optical recording device characterized by having a recording signal subtraction means for subtracting, and an optical recording device of a type that records information on an optical recording medium with a writing beam that changes according to a recording signal, means for generating a trailing beam separated from the same light source as the writing beam by a smaller level than the writing beam and trailing the writing beam in the information recording direction; and the optical recording medium of the trailing beam. and recording signal subtraction means for subtracting a signal that changes in synchronization with the recording signal from the detection signal by the detection means to confirm the recording state after recording the information. This is achieved by providing an optical recording/reproducing device characterized by having the following.

<Function> In this way, when there is a scratch on the recording surface, the detection signal of the reflected light of the preceding beam includes the scratch detection signal and the recording signal that changes in synchronization with the writing beam. By subtracting the recording signal from the reflected light detection signal, only the flaw detection signal can be extracted. In addition, the halo beam includes a reproduction signal similar to that used when reading pits formed by the writing beam, and a recording signal that changes in synchronization with the writing beam. By subtracting, only the reproduced signal can be extracted.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic circuit diagram of an optical information recording/writing device based on the present invention. In this device, a laser beam is irradiated onto, for example, the recording surface of an optical card using a known optical head structure. It records information. A laser diode 1 for emitting laser light is driven by a signal output from a laser driver 2 in response to a signal from a recording signal generation circuit (not shown), and laser light is emitted from the laser diode 1.

The light emitted from the laser diode 1 described above passes through a diffraction grating (not shown), for example, into a writing beam 4 as a main beam consisting of 0th-order light, and a pair of subsidiary beams consisting of 1st-order diffracted light. For an optical card traveling in the direction of the arrow in the figure, the left side in the figure of the two beams 5.6 that move back and forth in the relative movement direction of the writing beam 4 becomes the leading beam, and the right side becomes the trailing beam. The light beams are separated and irradiated onto the recording layer 3 of the optical card as shown by the imaginary lines in the figure. Note that the method for separating the writing beam 4, the leading beam 5, and the trailing beam 6 from the light emitted from one laser diode 1 is not limited to the three-beam method using the above-described diffraction grating. Further, since the optical card travels back and forth, when traveling in the opposite direction to the direction of the arrow, the beam 6 on the right side becomes the leading beam and the beam 5 on the left side becomes the trailing beam.

Each beam 4 to 6 is provided on both sides along the longitudinal direction of the recording layer 3.
A parallel guide 7 is provided for guiding the track direction. The light intensity of each beam 4 to 6 changes depending on the recording signal that drives the laser driver 2 described above, but the writing beam 4 reaches a level that can form pits in the recording layer 3 according to the recording signal, The leading beam 5 and the trailing beam 6 change similarly to the writing beam 4, but at a lower level than the writing beam 4, and both beams 5.6 are at a level that forms pits in the recording layer 3. is not reached.

The reflected light from the recording layer 3 of the writing beam 4 is irradiated onto the photodetector 9, which is divided into four parts in a square shape, centered on the intersection point in the center, and the reflected light of the leading and trailing beams 5.6 corresponds to each other. A photodetector 10.11 is illuminated. The reason why the photodetector 9 for the writing beam 4 is divided into four parts is to correct the focus and tracking errors of the writing beam 4 using a known method.

The detection signals from each photodiode of the photodetector 9 for the writing beam 4 are input in parallel to the amplifier 13, and the output signal from the amplifier 13 is input to the signal changeover switch 1.
2 to the reproduction signal detection circuit 17. Each photodetector 10. for the leading and trailing beam 5.6.
11 is transmitted to each corresponding amplifier 14.
．． 15, and output signals from amplifiers 14.15 are input to respective AGC circuits 18.19. The output of the photodiode 20 that monitors the output of the laser diode 1 described above is input to these AGC circuits 18 and 19 as a recording signal amplified to a predetermined level via an IV amplifier 21 as an amplifier. The detection signal of each photodetector 10.11 input to the AGC circuit 18.19 is gain controlled so as to be opposite to the increase or decrease in accordance with the recording signal that changes in synchronization, and changes in synchronization with the recording signal. The signal that is present is subtracted.

Further, the output signals from each AGC circuit 18 and 19 are switched by a signal changeover switch 16 and are manually inputted to either the signal changeover switch 12 or the flaw detection circuit 22 described above. Note that both signal' changeover switches 12 and 16 are controlled by a CPU (not shown) of this device.

Next, detection of scratches on the recording layer 3 during recording will be described below with reference to FIG. When the recording signal A from the laser driver 2 is output as shown in FIG. 3, pits 8 having the shape shown by hatching in the figure are sequentially formed in the recording layer 3. The reflected light from the recording layer 3 of the preceding beam 5 is detected by the photodetector 10, and is amplified to a predetermined level via the amplifier 14.
The output signal B, which is input manually to the C circuit 18, includes a similar waveform that is synchronized with the recording signal A.

By the way, if there is a scratch 23 on the recording layer 3 as shown in FIG. The output signal B is input to the AGC circuit 18. Note that the output of the laser diode 1 is set to a predetermined level even when the recording signal is at a low level, and the level of the portion corresponding to the scratch 23 decreases as shown in the figure.

Since the output signal B is gain-controlled by the recording signal A input to the AGC circuit 18 as described above,
The part that synchronizes with the edge of output signal B and recording signal A is
The signal component synchronized with the recording signal A is subtracted, and the AGC
The output signal C from the AGC circuit 18 has a differential waveform depending on the response speed of the devices constituting the circuit 18.
As shown in the figure, only the waveform of the scratch 23 remains. This output signal C is input to the flaw detection circuit 22, and by removing the differential waveform with a filter or the like, only the waveform of the flaw 23 can be obtained, and the presence or absence of a flaw can be easily detected. In addition, wound 2
3 is detected by the preceding beam 5, the reproduction signal of the pit 8 is not included in the output signal B, so the circuit for extracting only the waveform of the scratch 23 can be simplified.

Next, confirmation of the recording state of information by the pits 8 formed by the recording signal A will be described below with reference to FIG. Note that descriptions of the same parts as in FIG. 3 will be omitted.

Imagine a diagram in which the reflected light of the trailing beam 6 from the recording layer 3 is detected by the photodetector 11, and the detection signal that is amplified to a predetermined level via the amplifier 15 is synchronized with the recording signal A. The waveform shown by the solid line in the figure is obtained by superimposing the reproduced waveform by the pits 8 on the similar waveform shown by the line. In this case as well, the output of the laser diode 1 is set to a predetermined level even if the recording signal is at a low level, and the level of the portion corresponding to the pit 8 decreases as shown in the figure. do.

In this state, a correct reproduction signal cannot be obtained, but as in the case of flaw detection described above, the signal bone synchronized with the detection signal A of the detection signal is subtracted, and the part synchronized with the edge becomes a differential waveform. , only the reproduced waveform corresponding to pit 8 remains in the output signal E, as shown in FIG. This output signal E is manually input from the signal changeover switch 16 to the reproduction signal detection circuit 17 via the signal changeover switch 12,
After removing the differential waveform using a filter or the like as described above, the reproduced signal can be easily confirmed by comparing it with the recorded signal A.

In addition, by selectively switching the signal changeover switch 12, reading is performed using the main beam, which is the writing beam 4, during normal reading, and reproduction signals are read using the secondary beam, which is the trailing beam 6, only during writing. can be checked by

In this embodiment, recording on an optical card has been described, but the present invention is not limited to a recording device for an optical card, and can be used, for example, as a recording device for an optical disc.

[Effects of the Invention] As described above, according to the present invention, it is possible to easily detect scratches at the same time as writing. For example, in the case of a fatal scratch, writing is stopped and the writing is immediately moved to another sector or track. writing can be restarted, thereby improving the writing processing speed, and detecting flaws without being affected by the pits due to the preceding beam before the pits are formed. Also,
Since the reproduction signal can be checked at the same time as writing, processing speed can be improved, and since the reproduction signal is obtained by the trailing beam after pit formation, the recorded state can be ensured with the same reproduction signal as during normal reading. Can be checked. In addition, by performing flaw detection and checking using a beam obtained separately from the same light source as the writing beam, the circuit can be simplified, and by performing the flaw detection and checking at the same time as writing, the processing speed during writing can be increased. The effects are extremely large, such as improved performance.

[Brief explanation of drawings]

FIG. 1 is a schematic circuit diagram of an optical recording device based on the present invention. FIG. 2 is a diagram showing the position of each film with respect to the recording layer. FIG. 3 is a diagram showing the operation at the time of flaw detection. Fig. 4 is a time chart showing the operation when confirming the reproduced signal. 1... Laser diode 2... Laser driver 3.
... Recording layer 4... Writing beam 5... Leading beam 6... Trailing beam 7... Guide
8...Pits 9-11...Photodetector 12...Signal changeover switches 13-15...Amplifier 16...Signal changeover switch 17...Reproduction signal detection circuit 18.19...AGC circuit 20 ...Photodiode 21...IV amplifier 22...Flaw detection circuit 23.
··scratch

Claims (2)

[Claims] (1) An optical recording device that records information on an optical recording medium using a writing beam that changes according to a recording signal, the writing beam being separated from the same light source by a level smaller than that of the writing beam. a means for generating a leading beam which precedes the writing beam in the information recording direction; a means for detecting reflected light of the leading beam from the optical recording medium; and a means for detecting reflected light of the leading beam from the optical recording medium; 1. An optical recording apparatus comprising recording signal subtraction means for subtracting a signal that changes in synchronization with the recording signal from a detection signal by the detection means in order to detect defects in a recording medium. (2) An optical recording device of a type that records information on an optical recording medium using a writing beam that changes according to a recording signal, wherein the writing beam is separated from the same light source by a level smaller than that of the writing beam. means for generating a trailing beam that follows the writing beam in the information recording direction; means for detecting reflected light of the trailing beam from the optical recording medium; and recording of the information. 1. An optical recording/reproducing apparatus comprising: recording signal subtraction means for subtracting a signal that changes in synchronization with the recording signal from the detection signal by the detection means in order to confirm a subsequent recording state.