JPS6292135A - Mis-recording prevention circuit of optical disc device - Google Patents

Abstract

PURPOSE:To block mis-recording to a disc and to prevent the information already recorded from being destroyed by intermitting the recording information of an information recording system on its way when a tracking servo system causes a pull-in fault. CONSTITUTION:When the tracking servo system is in the pull-in state and a low level signal is outputted from a tracking lock detection circuit 11, a changeover circuit 12 is in on-state. Thus, the recording information is recorded on an optical disc 10 via a signal processing circuit 7, a changeover circuit 12, a laser drive 8 and a laser pickup 9. On the other hand, if the tracking servo system has a pull-in fault and a high level signal is outputted from the tracking lock detection circuit 11, the changeover circuit 12 is in off-state. Thus, the recording information is shut by the changeover circuit 12 and mis- recording onto an optical disc 10 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention provides a method for preventing erroneous recording fat IJ:. The present invention relates to circuits, and particularly to a circuit for preventing erroneous recording in write-once or erasable optical disc devices.

[Background of the invention]

Recording on a disc in a write-once or erasable optical disc device is generally performed as follows.

That is, subotos called bits are recorded along tracks called groups formed concentrically or spirally on the disk surface. This bit is
The reflectance or transmittance of light varies depending on the recorded information,
Moreover, the lengths and intervals are formed to be different.

On the other hand, information is read from a disk by using, for example, a laser pick amplifier to detect reflected light or transmitted light from the recording surface that is modulated depending on the presence or absence of a peer of the disk, and demodulates the detected light.

In addition, when recording information on a disk and reading information from the disk, a so-called tracking servo control device controls the movement of a tracking actuator for deflection so that the irradiated light accurately tracks the information track on the disk. That's what I do.

The conventional example will be further explained below with reference to the drawings.

FIG. 2 is a block diagram showing a schematic configuration of an information recording device of a conventional optical disc device. In the figure, 1 is a pair of photodiodes, 2 is a differential amplifier circuit, 3 is a phase compensation circuit, 4 is a tracking loop switch, 5 is a drive circuit, and 6 is a coil for driving a tracking actuator.

1 to 6 constitute a tracking servo system.

7 is a signal processing circuit for processing recorded information, 8 is a laser drive, 9 is a laser pickup, and 10 is an optical disc. 7 to 9 constitute an information recording system.

In FIG. 2, signals detected by a pair of photodiodes 1 are supplied to a differential amplifier circuit 2, so that
This becomes a tracking error signal, which is supplied to the phase compensation circuit 5. The Druskin group switch 4 controls whether or not the tracking error signal that has passed through the phase compensation circuit 5 is supplied to the drive circuit 5 by its on-off operation. Specifically, when starting the optical disc device, the tracking loop switch control signal turns off during the time until the focus servo control system (not shown) is controlled or during track jump, and the tracking error signal is turned off. On the other hand, it is in the on state during other periods and allows the tracking error signal to pass. The drive circuit 5 supplies a current corresponding to the tracking error signal to the tracking actuator drive coil 6. As a result, the deviation l of the tracking actuator is controlled so that the tracking error signal becomes zero. Therefore, the laser pickup 9
can accurately track the information track on the optical disc 10. The above is the operation of the tracking servo thread.

On the other hand, in an information recording system, recorded information is processed through signal processing 14.
The signal is converted into a predetermined modulated signal in path 7, and is further recorded on optical disc 10 via laser drive 8 and racer pickup 9.

However, such conventional optical disc devices have the following drawbacks.

In other words, if the tracking servo system malfunctions due to a certain cause and causes a pull-in failure that does not accurately track a predetermined track, recorded information may be transferred to the disk 10.
The disadvantage is that the information may be mistakenly recorded on the top, thereby destroying the information that has already been recorded. Such pull-in failures are particularly likely to occur immediately after high-speed access.

Incidentally, publications disclosing this type of device include, for example, JP-A-59-146445 and JP-A-59-146445.
177738 and the like.

[Purpose of the invention]

The object of the present invention is to eliminate the drawbacks of the prior art described above,
An object of the present invention is to provide an erroneous recording prevention circuit for an optical disc device that can prevent erroneous recording on an optical disc.

[Summary of the invention]

In order to achieve the above object, in the present invention, a switching means is provided in the information recording system, and when the tracking servo system has a pull-in failure, the switching means is switched to a signal obtained by the tracking servo system (for example, a tracking error signal). It is characterized in that it is configured so that it is turned off based on the information recording system, and the recorded information is cut off midway through the information recording system.

[Embodiments of the invention]

Hereinafter, the present invention will be explained using the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In this figure, the same reference numerals as in FIG. 2 represent the same or equivalent parts.

In FIG. 1, the tracking lock detection circuit 11 is
Based on the tracking error signal that is the output of the differential amplifier circuit 2, it is determined whether the tracking servo system is causing a pull-in failure or not, and if a pull-in failure is occurring, a high level signal is output. In addition, in a retraction operation state in which no retraction failure occurs, a low level signal is output.

The switching circuit 12 is a switching means disposed between the signal processing circuit 7 and the laser drive 8, and is controlled on/off in response to the low level signal and high level signal from the tracking lock detection circuit 11. .

Now, when the tracking servo system is in the pull-in operation state and a low level signal is output from the tracking lock detection circuit 11, the switching circuit 12° is turned on.
Recorded information is recorded on the optical disc 10 via a signal processing circuit 7, a switching circuit 12, and a laser pickup 9 that passes through a laser drive 8.

On the other hand, the tracking servo system is causing a pull-in failure.
When a high level signal is output from the tracking lock detection circuit 11, the switching circuit 12 is turned off at this time, so that the recording information is blocked by the switching circuit 12, and erroneous recording on the optical disc 10 is prevented. Ru.

FIG. 3 is a block diagram showing a specific example of the tracking lock detection circuit 11 of FIG. 1.

In the figure, a hysteresis amplifier 13 shapes an error signal component larger than a certain width out of the output signal of the differential amplifier circuit 2, that is, the tracking error signal, and outputs it as a rectangular wave signal. The retrigger pull mono multivibrator circuit (hereinafter simply referred to as M/M circuit) 14 is
The rectangular wave signal (pulse signal) is re-triggered at the rising edge of the rectangular wave signal (pulse signal), and is output as a pulse signal having a larger pulse width than the pulse signal. The low pass filter (LPF) 15 is M
/ Outputs a signal obtained by removing high frequency components from the output signal of the M circuit 14.

The H/L detection circuit 16 determines whether the output signal of the LPF 15 is at a higher level (H level) or a lower level (L level) than the scheduled threshold value, and outputs a high level signal accordingly. Outputs a level or low level signal.

Figures 4A to 4E are signal waveform diagrams of each part in Figure 3 when the tracking servo system has a pull-in failure, and Figures 5A to 5E show the tracking servo system pulling in. FIG. 7 is a signal waveform diagram of each part in FIG. 6 when the device is in the state; Note that the optical disc 10 of this embodiment has 2q spiral tracks.

Here, the operation of the tracking lock detection circuit 11 when the tracking servo system has caused a pull-in failure will be explained using FIG. 6 and FIGS. 4A to 4E.

When the tracking servo thread is pulled in incorrectly, the output signal of the differential amplifier circuit 2, that is, the hysteresis amplifier 1
The human power signal of 3 is in the 4th eA state. In other words, in the case of a pull-in failure, since the laser pickup 9 scans over several tens of tracks, the frequency of the jump signal is lower than the frequency of the jump signal generated during a track jump in the pull-in operation state, which will be described later with respect to FIG. 5A. frequency is quite high. Generally, the frequency of the jump signal in the pull-in operation state is, for example, 30 Hz, which corresponds to the disk rotation frequency, but is about several tens of KZ.

The hysteresis amplifier 13 shapes the input signal A into a pulse signal as shown in FIG. 4B and outputs it. M/M
The circuit 14 is retriggered at the rising edge of the pulse signal B to form a pulse signal having a width larger than the pulse period of the erroneous pulse signal B, and output the pulse signal. Therefore, the output signal of the M/M circuit 14 remains at a high level as shown by the solid line in FIG. 4C. The high level signal C is passed through the LPF 15.
and is supplied to the H/L detection circuit 16°. The solid line in the fourth diagram is the signal that has passed through LPFls. By the way, the threshold value of the H/L detection circuit 16 is
This is the level shown by the dashed line in the diagram. For this reason, when the pull-in is defective, the loop detection circuit 16 outputs a high-level signal as shown by the solid line in FIG. 4E.

Next, the operation of the tracking lock detection circuit 11 when the tracking servo yarn is in the pulling operation state will be explained using FIG. 6 and FIGS. 5A to 5E.

The output signal of the differential amplifier circuit 2 in this pull-in operation state,
That is, the tracking error signal consists of a large-amplitude jump signal T7 portion that occurs when a track jumps every rotation of the disk, and a small-amplitude, high-frequency error signal portion that occurs between the jump signals T7. Such a tracking error signal is shown in FIG. 5A.

The tracking error signal A is sent to the hysteresis amplifier 15.
When the jump signal T is supplied to the erroneous jump signal T, the hysteresis amplifier 16 separates the jump signal T from the error signal and outputs a pulse signal corresponding to the erroneous jump signal T. This pulse signal waveform is shown in FIG. 5B. The M/M circuit 14 is triggered by the rising edge of the pulse signal B, and outputs a pulse signal C shown in FIG. 5C, which has a larger pulse width than the pulse signal B. The pulse signal C is smoothed by passing through the LPF 15 and becomes a waveform signal as shown by the solid line in FIG. The threshold value of the H/L inspection circuit 16 is at the level shown by the dotted steel line in the fifth diagram. As a result, in the pull-in operation state, the H/L detection circuit 16 outputs a low level signal as shown by the solid line in FIG. 5E.

In the above explanation, the switching circuit 12 is arranged between the signal processing circuit 7 and the laser drive 8, but in the present invention, the switching circuit 12 is arranged before the signal processing circuit 7 or in the laser drive 8. It may be arranged between the drive 8 and the laser pickup 9, or it may be arranged inside the laser drive 8 to control the output of the laser drive 8.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, when the tracking servo system is causing a pull-in failure, it is possible to cut off the recording information of the information recording system midway.
Erroneous recording to the disc is prevented. As a result, a situation where already recorded information is destroyed can be avoided.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram showing an example of an information recording device of a conventional optical disc device, and FIG. 3 is a specific example of the tracking lock detection circuit of FIG. The block diagrams shown in FIGS. 4 and 5 are signal waveform diagrams of each part in FIG. 3. 1... Photodiode, 2... Differential amplifier circuit, 6
・・Tracking actuator drive filter, 7・・
・Signal processing circuit, 8...Laser drive, 9
...Laser pickup, 1o...Optical disc 1
11...Tracking lock detection circuit, 12...Switching circuit, 13...Hysteresis amplifier, 14...M
/M circuit, 15...L P F , 1
6...H/L detection circuit. Representative Patent Attorney Katsutoshi Ogawa / Atsushi 3

Claims (2)

[Claims] (1) In an optical disc device that has a tracking servo system and an information recording system, and is capable of additionally writing information or erasing recorded information on a disk recording medium having concentric or spiral tracks, the above-mentioned Based on the switching means provided in the information recording system and the signal obtained from the tracking servo system,
means for determining whether the tracking servo system is in a retraction operation state or in a retraction failure state; and when the result of the determination means is a retraction operation state, controlling the switching means to an on state to transfer recorded information to a subsequent stage; 1. An erroneous recording prevention circuit for an optical disc device, comprising: control means for controlling the switching means to an OFF state to cut off recording information when there is a failure in sending or retracting. (2) The erroneous recording prevention circuit for an optical disc device according to claim 1, wherein the signal obtained by the tracking servo system is a tracking error signal.