JPS61292227A - Optical disc device - Google Patents

Abstract

PURPOSE:To prevent a signal from being recorded on other track in error by providing an out-of-focus detection circuit detecting the disorder of focus and a beam output control means controlling an optical beam output with the output of the out-of-focus detection circuit. CONSTITUTION:An error amplifier circuit 38, a focus control circuit 41, a drive circuit 42 and a drive coil 43 constitute a loop of the focus control system. When a tracking-off detection circuit 31 and the out-of-focus detection circuit 39 detects an off-track or an out-of-focus, the output of the circuits goes to 'H' and the outputs are inputted to a OT circuit 40. Thus, either the tracking- off detection circuit 31 or the out-of-focus detection circuit 39 detects a tracking- off or an out-of-focus, the output of the OR circuit goes to 'H', the signal is inputted to a control signal generating circuit 32, from which a control signal disabling laser recording is generated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an optical disc device that records and reproduces information on an optical disc having a guide groove, and the present invention is directed to recording information when out of focus or tracking occurs during recording of information. This invention relates to the output control of optical beams for use.

[Conventional technology]

FIG. 3 is a block diagram of a conventional optical disc device disclosed in, for example, Japanese Patent Laid-Open No. 59-65946. In the same figure, ■ is a disk, 2 is a motor for rotating the disk, and 3 is a disk rotation motor.
is a recording modulation circuit, 4 is a laser drive circuit, 5 is a laser diode, 6, 9° and 10 are convex lenses, 7 is a semi-transparent mirror, 8 is a tracking mirror, 1) is a mirror, 12
．． 13 is a PIN photodiode, 14 is a tracking mirror drive coil, 15 is an optical system moving section, 16 is a slider moving section, 17a to 17d are amplifiers, respectively.
18 and 24 are differential amplifiers, 19 is a summing amplifier,
20 is a video signal reproducing circuit, 21 is an address identification circuit, 22 is a microcomputer, 23 is a keyboard, 25 is an error amplifier, 26
27 is a tracking control circuit, 27 is a feed motor control circuit,
28 is a drive circuit, 29 is a feed motor, 3o is a trunking mirror drive circuit, 31 is a tracking error detection circuit, and 32 is a control signal generation circuit.

The disk 1 is rotated at a high speed of, for example, 1800 rpm by a disk rotation motor 2. When recording information on this disk l, a video signal input from a TV camera or the like (not shown) is modulated by a recording modulation circuit 3, then input to a laser drive circuit 4, and the drive output from there generates a laser beam. The output light of the diode 5 is intensity-modulated.

The reason why the laser diode 5 is used as a light source is that only one light source is required for recording and reproduction, making it possible to reduce the size and power consumption, and to directly modulate and control the recording light.

Output light generated from the laser diode 5 passes through a convex lens 6 and a semi-transparent mirror 7, is reflected by a tracking mirror 8, and is focused onto the disk 1 by a convex lens 9. The reflected light from the disk 1 passes through the convex lens 9 again, is changed direction by the tracking mirror 8 and the semi-transparent mirror 7, and then passes through the convex lens 10, where it is reflected by the mirror 1).
Pi to obtain the focus error signal while
P2's two-split PIN hot diode 13, the other is PI for obtaining a tracking error signal, and P2's two-split P
The light is guided to the IN hot diode 12 and photoelectrically converted.

The signal amplified via the amplifiers 17C and 17d is input to the differential amplifier 18, and the output of the differential amplifier 18 is used as a focus error signal, and is set so that the spot diameter of the convergent light beam is approximately 1 μm. The convex lens 9 is controlled by focus control. - force amplifier 17a, 1
A tracking error signal is obtained from the output of the differential amplifier circuit 24 that generates a difference signal between the respective outputs of the output terminals 7b, and the tracking error signal is sent to the drive circuit that drives the tracking mirror 8 via the error amplifier circuit 25, the tracking control circuit 26, and the drive circuit 30. It is applied to the coil 14 to control the deflection angle of the tracking mirror 8 so that the error signal becomes zero.

Further, the recording guide grooves are concentrically carved on the disk 1 from the inner circumference to the outer circumference. In order to send the writing spot from the inner circumference to the outer circumference on the disk l along this guide groove, a part of the tracking mirror drive signal is sent via the feed motor control circuit 27 to the drive circuit 28 that drives the feed motor 29. Slider 1 equipped with optical system moving unit 15
6 in the radial direction of the disk 1.

When reproducing information recorded on the disc 1, the output light of the laser diode 5 is set to a lower output than the output light during recording. The light generated by the laser diode 5 passes through a convex lens 6 and a semi-transparent mirror 7, is directed by a tracking mirror 8, and is focused onto the disk 1 by a convex lens 9, as in the case of recording.

The light reflected on the disk 1 passes through the convex lens 9 again, its direction is changed by the total reflection mirror and the semi-transparent mirror 7, and after passing through the lens 10 it is split into two parts by the mirror 1), one of which is sent to the PIN photodiode 13. , the other is led to the PIN photodiode 12 and used for focus and tracking control during playback. Further, the two signals obtained from the PIN photodiode 13 are converted into a sum signal by the amplifier circuit 19,
This signal is input to the video signal reproducing circuit 20, where it is converted into the original video signal. In the video playback signal, an address signal corresponding to each track is recorded, for example, during the vertical retrace period, and the address signal of the recording track is read out by the address identification circuit 21 and sent to the microcomputer 22 (hereinafter abbreviated as microcomputer). ) is entered.

Now, during recording, if the optical spot is unable to follow the tracking control due to external vibrations, or due to radial groove movement or scratches in the groove due to eccentricity of the disk, and tracking deviation occurs, the recording has already occurred. In order to avoid overwriting again on a previously recorded track, or erroneously recording on a track that has not yet been recorded, in the conventional example described above, a tracking error detection circuit 31 and a control signal generation circuit 32 are provided, and an error amplification circuit 25 is provided. A detection circuit 31 detects a tracking error from a tracking error signal outputted from a tracking error signal, and the control signal generation circuit 32 generates a control signal using this detection output to control the laser drive circuit 4, thereby disabling the recording operation. I'm doing it.

Note that the signal path from the microcomputer 22 to the control signal generation circuit 32 is a signal path for later sending a reset signal.

Next, the operation of the tracking deviation detection circuit 31 will be explained using FIG. 4.

In the figure, 33 is a level detection circuit.

FIG. 5 is a waveform diagram of various signals in FIG. 4.

The operation will be explained with reference to FIGS. 4 and 5.

When tracking control is being performed normally, the amplitude of the tracking error signal is small, as shown in FIG. Become.

This signal is input to the level detection circuit 33 set with the reference voltage shown as El in FIG. 5(al), and by detecting the level exceeding El, a waveform as shown in FIG. 5(b) is generated. A signal is obtained.The reference voltage E1 is set approximately halfway between the tracking error voltage obtained when the tracking control is operating normally and the peak error voltage obtained when the tracking control is off.

When the tracking control is normal, the level of the tracking error signal is lower than the reference voltage E1, so no pulse is output from the level detection circuit 33. However, when the tracking control is off, the level of the tracking error signal is lower than the reference voltage E1. Therefore, a pulse is output as shown in FIG. 5(b). When this pulse signal is input to the clock terminal T of the D-type flip-flop 32, if a tracking control error occurs, the pulse signal is inputted to the clock terminal T of the D-type flip-flop 32.
) is obtained as a control signal. This signal is input to the laser drive circuit 4 and controlled so that recording is disabled.

[Problem that the invention seeks to solve]

However, in the conventional example described above, since tracking error signals are used to detect tracking errors, if the focus is disturbed due to scratches or the like on the disk, detection will be missed.

This point will be explained below.

FIG. 6 shows tracking error detection characteristics when defocus occurs. 37 shows a cross section of the information recording surface.

34 is a guide groove. 35a shows the shape of the light spot at the focused point, and 36a shows the tracking error detection characteristic when this light spot crosses the guide groove. As the focus goes out, the shape of the light spot on the board becomes broader as shown at 35b, the tracking error detection resolution decreases, and the tracking error detection signal amplitude becomes smaller as shown at 36b. When the focus is further removed, the tracking error detection signal amplitude becomes zero, that is, it becomes completely undetectable.

Generally, the defocus that causes such a decrease is several μm to 10 μm, but the linear range of focus error detection is about 1) 0l1 to several tens of μm. Therefore, due to defects in the medium surface or sudden surface deflection, the focus may be lost by a few microns.
When the tracking error detection signal amplitude is disturbed by about m to 10 μm, the amplitude of the tracking error detection signal decreases to near zero, so that in the conventional method, even if the tracking error occurs, it cannot be detected. If the amount of focus deviation is within the linear range, focus control and tracking control will eventually return to normal, but the tracking control will not be detected (it will follow another track. Therefore, during recording operation When this phenomenon occurs, the tracking error detection does not work, so the recording operation continues and there is a problem in that the recorded trunk or unrecorded track is erroneously recorded.

This invention was made to solve the above-mentioned problems, and even if tracking is caused by a focus shift (including a simple focus disturbance) during recording, it is possible to record to a different trunk by mistake. The purpose of this is to control recording so that nothing happens.

[Means for solving problems]

An optical disc device according to the present invention includes an out-of-focus detection circuit that detects a disturbance in focus, and a beam output control means that controls the output of a light beam using the output of the out-of-focus detection circuit.

An optical disc device according to another aspect of the invention includes a tracking-out detection circuit for detecting tracking disturbances and a focus-out detection circuit for detecting focusing disturbances, and uses at least one of the out-of-focus detection outputs of the rain detection circuit to emit light from a recording light source. The beam output is controlled.

[Effect]

In the present invention, the beam output control means controls the output of the light beam based on the output of the out-of-focus detection circuit.

In another aspect of the present invention, the beam output control means controls the output of the light beam based on the output of the out-of-focus detection circuit or the output of the out-of-tracking detection circuit.

〔Example〕 Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, numerals 1 to 32 are similar to the conventional device described above. (However, parts unnecessary for the explanation have been omitted.)38
39 is an out-of-focus detection circuit; 40 is an OR circuit; 41 is a focus control circuit; 42 is a drive circuit; 43 is a convex condensing lens 9
This is the drive coil.

Next, the operation will be explained. Error amplification circuit 38. Focus control circuit 41. Drive circuit 42. The drive coil 43 constitutes a loop of the focus control system, and further explanation will be omitted. When both the tracking out-of-focus detection circuit 31 and the out-of-focus detection circuit 39 detect out-of-focus, “
- As an example, use the same level detection circuit 33 as shown in FIG. 4. These outputs are connected to the OR circuit 4.
0 due to manual input, tracking error detection circuit 3
1 or the out-of-focus detection circuit 39 detects out-of-focus, the output of the OR circuit 40 becomes "H" and the recording operation is disabled. Here, the control signal generation circuit 32 functions as a beam output control means for controlling the output of the light beam. Furthermore, the explanation when the tracking deviation detection circuit operates is exactly the same as in the conventional example, and will therefore be omitted. A case will be described in which only the out-of-focus detection circuit operates. The reason why such a phenomenon occurs has been mentioned in the section regarding the problems of the conventional example, but will be described again. Although the guide groove is normally formed, if the surface of the recording medium has sharp irregularities in the vertical direction (focus direction), the focus control will not be able to follow it and the focus will be out of focus. This situation is shown in FIG. At time t2, the focus error signal increases rapidly due to the focus being out of focus, but when the unevenness fluctuation factor disappears, focus control recovers to almost normal state at time t3. During this time, the tracking error signal drops to zero due to the focus being lost, and as a result, the tracking control that had been normal until now becomes impossible, and the track enters another track. However, since the tracking error signal is zero, the tracking error detection circuit 310
The reference voltage E1 is not exceeded, and no tracking error is detected. On the other hand, by setting the out-of-focus reference voltage F1 of the out-of-focus detection circuit 39 as shown in the figure, the output of the out-of-focus detection circuit 39 becomes "H" and the OR circuit 40
The signal is inputted to a control signal generation circuit 32 through which a control signal is generated to disable the laser for recording. Depending on the type of defect in the disk medium, tracking-out detection and focus-out detection may be detected at the same time, but it goes without saying that recording will be impossible in this case as well.

Note that the above explanation focused on preventing erroneous recording due to tracking errors, but this is not the focus.

A sector that includes areas where tracking is likely to be disturbed is detected during recording using an out-of-focus detection circuit and an out-of-tracking detection circuit, and recording is interrupted.
By recording the information of that sector again in another sector, for example, the next sector, it is possible to improve the reliability of the information.

To this end, reliability is further improved by detecting out-of-focus and tracking errors.

In the above embodiment, the tracking deviation detection circuit 3.1.
As shown in FIG. 2, the out-of-focus detection circuit 39 has been explained using the level detection circuit 33 which has a reference voltage only for the positive potential, but it is also a window comparator that has reference voltages for both the positive and negative potentials, and when the window is exceeded, A deviation detection signal may also be output.

Also, focus control such as magneto-optical disks.

It goes without saying that the present invention can be applied to any information recording/reproducing system that includes a tracking control means.

〔Effect of the invention〕

As explained above, according to the present invention, the beam output Il control means controls the output of the light beam based on the output of the out-of-focus detection circuit. Tracking errors can be reliably detected even if the track is tracked incorrectly, preventing erroneous recording on a different track, and improving the reliability of information.

According to another aspect of the present invention, the beam output control means controls the output of the light beam based on the output of the out-of-focus detection circuit or the output of the out-of-tracking detection circuit, so that in addition to the above-mentioned effects, tracking Even if a track is detected, it will not be recorded on a different track by mistake.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an optical disc device according to an embodiment of the present invention, FIG. 2 is a waveform diagram of out-of-focus detection operation,
FIG. 3 is a block diagram of a conventional optical disc device, FIGS. 4 and 5 are circuit diagrams of a tracking error detection circuit and a waveform diagram of a tracking error detection operation, and FIG. 6 is a waveform diagram of a tracking error signal. DESCRIPTION OF SYMBOLS 1... Disk (recording medium), 4... Laser drive circuit, 5... Laser diode, 26... Tracking control circuit, 31... Tracking deviation detection circuit, 32... Control signal generation circuit (beam output control means), 39...out-of-focus detection circuit, 40.
...OR circuit, 41...focus control circuit. Agent: Masuo Oiwa (2 idiots) Figure 1 1-11,000-chair 7 4--c-SoftBank circuit 5--Laser diode 26-) Lucky lucky 1'# times 3 l ---) U, Sonia 〒 〒 〒 も 1 is I ° song (introduction 3 bi ± times 32 --- common 1 heather seal 1 stone can be hung 39 ---
) Ding - Kasu (Saisu゛ Yisai 4 (Sho circuit 2nd cause 3 Figure 4 Figure 33 (p)

Claims (2)

[Claims] (1) A recording light source, an optically recordable recording medium,
An optical disc device comprising: a focus control means for focusing a light beam emitted from the recording light source onto a minute spot on the medium; and a tracking control means for correctly tracking the focused spot on a guide groove on the medium. An optical disc device according to claim 1, comprising: out-of-focus detection means for detecting disturbances in focus; and beam output control means for controlling light beam output using the output of the out-of-focus detection means. (2) a recording light source, an optically recordable recording medium,
An optical disc device comprising: a focus control means for focusing a light beam emitted from the recording light source onto a minute spot on the medium; and a tracking control means for correctly tracking the focused spot on a guide groove on the medium. The light beam output of the recording light source is controlled by an out-of-focus detection circuit for detecting focus disturbance, a tracking-out detection circuit for detecting tracking disturbance, and at least one of the out-of-focus detection outputs from both of the detection circuits. 1. An optical disc device comprising: beam output control means.