JPS61145731A - Optical disk device - Google Patents

Abstract

PURPOSE:To secure completely the secrecy of data and also to obtain easily the control information at data record/reproduction by detecting a prescribed mark after comparing the reflected light quantity signal obtained by irradiating the light to the prescribed mark part with the output signal obtained by passing said reflected right quantity signal through an LPF and adding offset. CONSTITUTION:An analog switch 4 receives a data area signal (2) with start of the detection of data and releases the short-circuit of an operational amplifier 3. Then a detection signal (1) supplied to the amplifier 3 is shaped in wave form by a feedback circuit consisting of a resistor R3 and a capacitor C1 and has a prescribed time constant tau and sent to an operational amplifier 5 of the 2nd stage. The voltage obtained by controlling the power supplies +15 and -15 by a variable register RV is applied as the offset voltage to the signal sent through the amplifier 5. Thus a signal (3) is obtained and sent to a (-) terminal of a comparator 6. While the signal (1) is sent to a (+) terminal of the comparator 6. The comparator 6 compares the signal (1) with the signal (3) and the coincident signal waveform is sent to a circuit (not shown here) as a detection signal (4) for erasion mark (a).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a write-once optical disc device that optically records/reproduces data, and in particular to a write-once optical disc device that continuously irradiates a light beam for a predetermined data length onto an optical disc medium. The present invention relates to an optical disc device that accurately reads predetermined marks formed by

Optical disk devices, which are expected to serve as high-capacity external storage devices for information processing devices, are capable of high-density recording more than ten times that of conventionally used magnetic disk devices. It has the disadvantage of a very high error rate due to non-uniformity.

On the other hand, data is recorded in an optical disk device.

A hole (focus) is created by irradiating a light beam onto the surface of the optical disc medium.
Since this is done by opening the file, long-term storage of data is possible.

However, when an error occurs during data recording in a predetermined area, or if you want to erase data that has already been recorded to maintain confidentiality, there is no way to accurately detect that the data is being erased, and the data must be erased. There has been a strong desire to put into practical use an optical disc device equipped with a method for accurately detecting areas.

[Prior art and problems to be solved by the invention] FIG. 5 is a block diagram of an optical system of a write-once optical disc device.

FIG. 6 shows a state of recording/reproducing data on an optical disc medium, and FIG. 7 shows a schematic diagram of the structure of the optical disc medium.

Write-once optical disc devices generally use recording materials that do not require post-recording image processing. By strongly focusing the laser beam onto this recording material, the recording film 1 is thermally
Data is recorded by making a focus (hole) on the recording film 1 (there is also a method of changing the recording film 11, but in this example, the method of making a pit (hole) will be mainly explained).

The laser beam narrowed down by the diaphragm lens 34 has a diameter of 1
The optical disc medium 12 is made into a minute spot of ~2 μm.
Irradiate the top and the pits (holes) are formed.

The diameter is approximately 0.6 to 1.0 μm. In addition, the pit (
When recording data by forming holes (holes), the output of the laser diode 31 on the recording film 11 is about 5 to lomW. Also, during data reproduction, approximately 1 to 2
It is n+W.

During both data recording and reproduction, the irradiated laser beam is used to detect changes in the amount of transmitted light from the recording film 11 (method shown in FIG. 6(A)) or reflected light (method shown in FIG. 6(B)). It is detected by the photodetector 32, and a detection signal (2) is obtained.

That is, when recording data, the laser diode 31 is caused to oscillate at a high output (Equation 101) in response to an input signal transferred from a circuit not shown, and pits are recorded on the optical disk medium 12.

On the other hand, when reproducing data, the laser diode 31 is
Continuous oscillation is performed using W, and the reflected light beam from the optical disk medium 12 is guided to the photodetector 32 by a beam splinter 35 for signal detection. Note that the diaphragm lens 34 and the tracking mirror 33 are movable in the direction of the arrow in order to follow minute pits (holes) on the optical disk medium 12.

Such an optical disk medium 12 has a structure as shown in FIG. 7 (top view and sectional view). That is, it consists of a transparent substrate 10 and a recording film, and the recording film 11 consists of a preformat section 1 in which index marks, trunk numbers, sector numbers, etc. are recorded in advance, and a groove section 2 for recording data. There is.

The preformat section 1 and the groove ('a) section 2 are formed on a transparent substrate 10 using a stamping technique, and then a recording film 11 is deposited thereon. Data recording/reproduction is performed by irradiating the recording film 11 with a laser beam while tracking the groove portion 2.

When processing data recorded by such an optical disc device as invalid data due to a defect in the optical disc medium 12, etc., the following method has conventionally been used.

In other words, management information necessary for data recording/reproduction (for example,
Validity/invalidity of recorded data in a predetermined sector, recorded sector number, etc.) are separate storage devices.

For example, when data is stored in a floppy disk device or the like and data in a predetermined sector is to be erased, invalid data is erased by performing processing such as erasing the management information on the other storage device.

However, with this method, if there is a failure in another storage device, etc., data will be reproduced even if it is an invalid data part, which poses a problem in terms of data confidentiality. It has been devised to form erase marks on the optical disk medium 12 by continuously irradiating a predetermined length of the data recording portion with a laser beam.

However, it is not possible to detect erase marks recorded using this method.
, when using conventional recording/playback means -9 pits (holes)
In order to record the holes that were drilled and re-drilled.

Erase marks cannot be recorded reliably due to effects such as the diffusion of the thermal energy of the laser beam.

Therefore, there was a problem in that accurate erase mark detection was not possible.

[Means for solving problems]

An object of the present invention is to realize a new optical disc device that solves the above-mentioned problems.

The problem is that the reflected light amount signal obtained by detecting the reflected light of the light beam irradiated on a predetermined mark part and the above-mentioned foul light amount signal are passed through a predetermined low-pass filter circuit, and then a predetermined offset is added to the output signal. Compare with the signal.

The problem is solved by an optical disc device according to the present invention that detects the predetermined mark.

[Effect]

In other words, a predetermined mark (erase mark) portion recorded by continuously irradiating a predetermined portion of an optical disk medium with a laser beam for a predetermined data length is reflected by the reflected light amount signal of the laser beam irradiated with the light amount during playback, and the reflected light amount. By passing the signal through a low-pass filter circuit to perform an integration operation and comparing the level value with the level-shifted signal,
This makes it possible to reliably detect a steep change in the amount of reflected light between the data recording area and the predetermined mark (erase mark) area.

〔Example〕

The gist of the present invention will be specifically explained below with reference to embodiments shown in FIGS. 1 to 4.

FIG. 1 is a block diagram showing an embodiment of an erase mark detection circuit according to the present invention, and FIG. 2 is a diagram showing the recording state of erase marks on an optical disc medium.

FIG. 3 shows a reproduction signal waveform of an optical disc medium, and FIG. 4 shows an example of an application of an erase mark. The same reference numerals indicate the same objects throughout the figures.

Next, the operation of this embodiment will be explained.

The write-once optical disc device uses an optical disc medium 12 in which a recorded portion cannot be erased and recorded again. Therefore, a recording 2, for example, a predetermined mark, is required to distinguish between data-recorded portions and unrecorded portions on the optical disc medium 12.

Furthermore, even if it is desired to erase data from a previously recorded data portion for the purpose of data security, etc., the purpose can be achieved by continuously recording predetermined marks.

These predetermined marks a (hereinafter referred to as erase marks a) are generated by a high output (several tens of mW) from the laser diode 31.
) is continuously oscillated for a predetermined length to erase the erase mark a.
is recorded on groove 2 as shown in FIG.

The erase mark a recorded in this manner is reproduced as follows. That is, the laser diode 31 is caused to oscillate continuously at several mW and irradiates the optical disk medium 12, and the amount of reflected light is detected by the photodetector '32. The detection signal (2) at this time has a signal waveform shown in FIG. 3 (1).

The optical detector 32 is composed of four sensors (not shown), and the sum of the detection signals of the respective sensors (not shown) is used as the detection signal (2) of the photodetector 32. Further, this detection signal (2) is a detection of a DC fluctuation component of the sum of detection signals from a sensor (not shown).

Since data was recorded in the erase mark 3 (C) shown in Figure 3 (1), the data could not be completely erased due to the diffusion of the thermal energy of the irradiated laser beam. When reproduced, noise will remain in the reproduced signal (detection signal ■). Therefore, the signal is passed through a low-pass filter circuit to perform processing such as noise removal.

The block diagram shown in FIG. 1 is a circuit showing an embodiment of the present invention for detecting the erase mark 3 section (C). The operational amplifier 5 is a circuit that adds a predetermined offset voltage to the output from the low-pass filter.

The final stage is a comparator 6, which is a circuit that compares the signal (2) obtained by adding a predetermined offset to the output from the low-pass filter and the signal (2).

Analog switch 4 is normally shorted.

That is, the preformat 1 part (al
At the time of detection, the output of the operational amplifier 3 is set to zero voltage by the analog switch 4 (controlled by the signal ■).

This consists of briformant part 1 (a) to data part (b
), there is a part where the light intensity changes sharply, similar to when changing from data part (b) to erase mark 3 part (C), and this is to avoid misdetecting this as erase mark a. It is.

When data detection is started, the analog switch 4 receives the data area signal (2) from a circuit not shown, the analog switch 4 releases the short circuit of the operational amplifier 3, and the detection signal (2) is input.

The detection signal (2) sent to the operational amplifier 3 is shaped by a feedback circuit (consisting of a resistor R3 and a capacitor C1) having a predetermined time constant τ, and is sent to the second stage operational amplifier 5.

In addition, the feedback circuit (resistor R3, capacitor C1
In this example, the time constant τ of
It has been selected as ec. This is erase mark 3 (C
) is set to approximately 11 μsec, this is to avoid detection of signals smaller than this time width (signals of defects, noise, etc. in the optical disk medium 12).

The operational amplifier 5 connects the output signal with a 15v power supply.
A voltage (approximately 100 mV in this embodiment) adjusted from the power source -15V by a variable resistor RV is added as an offset voltage and sent to the (-) terminal of the comparator 6 as a signal (2). On the other hand, the signal ■ is sent to the (+) terminal of the comparator 6, and the comparator 6 compares the signal ■ and the signal ■ and shows the matched signal waveform as the erase mark a detection signal ■. Send to a circuit that does not exist.

In the above embodiment, the erase mark a is detected as a mark when recorded data is erased, but by assigning meaning to the location where the erase mark a is recorded on groove 2, various identification signals can be detected. It can be used as

2. For example, as shown in FIG. 4, a write mark (d) is used to distinguish between recorded and unrecorded portions of data.
, and can also be used as marks (e) and (e)' for separating data in data-recorded portions.

〔Effect of the invention〕

According to the present invention as described above, it is possible to record the erase mark directly on the medium and detect this erase mark reliably, so that it is possible to completely retain the data, and furthermore, it is possible to record the erase mark directly on the medium. By using it as various recognition marks, there is an effect that management information at the time of recording/reproducing data can be obtained more easily.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an erase mark detection circuit according to the present invention. FIG. 2 is a diagram showing the state of erasure mark recording on an optical disc medium. FIG. 3 shows the reproduction signal waveform of the optical disc medium. Figure 4 is an example of how erase marks are applied. FIG. 5 is a diagram showing the configuration of the optical system of the write-once optical disc device. FIG. 6 is a diagram showing the state of data recording/reproducing on an optical disc medium. FIG. 7 is a schematic diagram of the configuration of an optical disc medium. are shown respectively. In fig. 1 is the preformat section, 2 is the groove section. 3.5 is an operational amplifier. 4 is an analog switch, 6 is a comparator. 10 is a transparent substrate, and 11 is a recording film. 12 is an optical disk medium, and 30 is an optical system mechanism. 31 is a laser diode, and 32 is a photodetector. 33 is a follow-up mirror, and 34 is a diaphragm lens. 35 is a beam splinter, and 36 is a lens. are shown respectively. No. 3N Procedural Dispute Book (Autonomy / 1982 Patent Application No. 267924 2, Name of invention Optical disk device 3, Person making amendments Interview with the case Patent applicant address 1015 Kamiodanaka, Nakahara-ku, Yozaki City, Kanagawa Prefecture Street address (5
22) Name: Fujitsu Ltd. 4, Agent address: 1015 Fujitsu Ltd., 1015 Kadenaka, Nakahara-ku, Kanagawa MIX City, Fujitsu Ltd. No date of amendment order 1, F! The claims of Book A are amended as follows. rll)) A preformat section in which information regarding racks and sectors, timing information, etc. are recorded in advance, and a guide groove for tracking. Data is optically recorded by irradiating a light beam output from a laser diode onto a medium surface consisting of a groove portion for recording data, and at the same time, predetermined data is transferred to a data-recorded area or an unrecorded area on the medium surface. Detecting the reflected light of the light beam that was irradiated on the predetermined mark part of the original disk device for recording a predetermined mark by continuously emitting the light beam for a length of %M and comparing it with the output signal obtained by adding An optical disc device characterized in that the predetermined mark is detected. (2) The predetermined low-pass filter circuit is composed of a feedback section consisting of a resistor and a capacitor of a predetermined value, an operational amplifier, and an analog switch section, and when reading information from the preformer section, 2. The optical disc device according to claim 1, wherein the capacitor is short-circuited by the analog switch section. 2. Correct "approximately 100 mVJ to approximately -xoomvJ" in the second line of page 12 of the specification. 3. Correct the figures 1 and 3 of the drawings as shown in the attached sheet.

Claims (2)

[Claims] (1) A laser diode is placed on the medium surface, which consists of a pre-format area where information on tracks and sectors, timing information, etc. are recorded in advance, and a groove area that has a guide groove for track king and records data. An optical disk device that optically records data by irradiating an output light beam and records a predetermined mark by continuously irradiating the light beam for a predetermined data length onto a data-recorded area or an unrecorded area on the medium surface. A reflected light amount signal obtained by detecting the reflected light of the light beam irradiated on the predetermined mark portion and the reflected light amount signal are passed through a predetermined low-pass filter circuit, and further a predetermined offset is added. An optical disc device characterized in that the predetermined mark is detected by comparing the predetermined mark with an output signal. (2) The predetermined low-pass filter circuit includes a feedback section including a resistor and a capacitor having a predetermined value, and a logic operation section;
The claim includes an analog switch section, and when reading information from the preformat section, the capacitor is short-circuited by the analog switch section and the output of the predetermined low-pass filter circuit is turned off. The optical disc device according to item 1.