JPH0266734A - Optical disk device - Google Patents

Abstract

PURPOSE:To position a track at a high accuracy by providing a lens misregistration signal generating means and a waveform shaping means to generate a track cross pulse from the output signal and the output signal of a tracking error signal means. CONSTITUTION:When the position of a lens is dislocated by a lens misregistration signal generating means 10, the quantity of the light to enter a lens position detector 12 is changed. Consequently, by the detector 12, an electric signal corresponding to the position change of a lens is outputted. The output signal of the detector 12 is subtracted by a differential amplifier 14 and becomes a lens position dislocation signal 15. Consequently, by comparing and shaping the misregistration signal 15 and a tracking error signal 59 with a comparator which is a waveform shaping means 20, a track cross pulse 21 to cancel the influence of the offset can be obtained. The pulse 21 is inputted to a track counter 58 and the number of the track crossings is counted at a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc device, and more particularly to an optical disc device for counting the number of track crossings with high accuracy during a high-speed track access operation.

[Prior Art] In an optical disc device, a track access operation is generally performed when recording and reproducing information.

During the access operation, the difference between the current track address and the target track address is determined, and the track is moved by the difference to position the target track.

FIG. 3 shows a conventional example. In the conventional example shown in Fig. 3,
The Retz beam from the laser light source 51 is passed through a collimating lens 52 . The light passes through the beam converter 53 and the objective lens 54 and is irradiated onto the optical disk 55 . Further, the direction of the reflected beam from the optical disk 55 is changed by a beam splitter 53 and becomes an input to a tracking error signal generating means 56.

The tracking error signal 59 which is the output of the tracking error signal generating means 56 becomes an input to the zero slicing means 57, and the zero slicing means 57 outputs a tracking cross pulse 60 to the track counter 58.

Next, the operation of this conventional example will be explained. A laser beam irradiated from a laser light source 51 is focused by a collimating lens 52 to become a parallel beam, transmitted through a beam splinter 53, focused by an objective lens 54, and then released onto an optical disc 5.
Focus on the surface of 5. Next, the light reflected on the surface of the optical disk 55 contains a signal that determines whether it is on or between the grooves of the track, is focused by the objective lens 54, becomes a parallel beam, and is deflected by the beam splitter 53 for tracking. It becomes an input to the error signal generating means 56.

In the trunking error signal generating means 56, the tracking error signal 59 corresponding to the track groove 2 is generated as the 6th tracking error signal 59.
The output is as shown in Figure (b).

The tracking error signal 59 is zero-sliced by the zero-slicing means 57 to become a track crossing pulse 60 as shown in FIG.
is counted. This count corresponds to the number of tracks traversed, so if the vehicle stops when the target count is reached, the target track address position is reached.

(Problem to be Solved by the Invention) However, in the above conventional example, rough positioning is performed by the head moving mechanism during high-speed l/rack access operation.At this time, the moving speed of the head moving mechanism is determined by the speed reference signal. It is set to have a constant acceleration or constant deceleration depending on the remaining distance during movement.When this acceleration and deceleration operation is performed, an external force is applied to the lens, so the position changes depending on the acceleration or deceleration. A shift occurs in the lens, and this positional shift causes an offset in the tracking error signal as shown in FIGS. 4 and 5.

If the band of the lens positioning servo system is ωC, a positional deviation of α/ωC2J will occur with respect to the acceleration α during head movement, so the more the acceleration is increased to perform high-speed access, the more the tracking error signal will decrease. The amount of offset increases.

Since the amplitude of the trunking error signal is modulated in the data recording section and the preformat section, if an offset occurs in the tracking error signal as shown in FIG. 7, an omission will occur in the l-rack crossing pulse. .

This makes it difficult to accurately measure the number of track crossings, causing the problem that the target trunk address position shifts.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to improve the disadvantages of the conventional example, and to provide an optical disk device that can count the number of track crossings with high precision and position the trunk with high precision, especially during high-speed track access operations. be.

[Means for Solving the Problems] Therefore, in the present invention, when recording or reproducing information by irradiating light from a light source onto a recording medium through a lens system, the number of track crossings of the head is reduced. For counting purposes, a tracking error signal generating means is provided for generating a trunking error signal corresponding to the deviation of the beam spot on the recording medium from the track center using reflected light from the recording medium. Further, a lens position deviation signal generation means for generating a lens position deviation signal during a 1-rack following operation and a track access operation, and a track crossing pulse is generated from the output signal of the tracking error signal means and the output signal of the lens position deviation signal generation means. The configuration includes a waveform shaping means for generating the waveform. This aims to achieve the above-mentioned purpose.

[For production]

During track following and track access operations, the amount of lens positional deviation that is the cause of offset is detected by the lens positional deviation signal generating means, and the waveform of the tracking error signal is shaped in response to this lens positional deviation signal to correct the offset. I do.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The embodiment shown in FIG. 1 includes a light source 51, a collimating lens 52 that collects the light from the light source 51 and makes it parallel, and the light from the collimating lens 52 travels straight as it is and is reflected from a recording medium 55. A recording/reproducing means includes a beam splitter 53 that changes the direction, an objective lens 54 that focuses the light transmitted through the beam splitter 53 on the surface of the recording medium 55, and a beam reflected from the recording medium 55. Accordingly, it has a tracking error signal generating means 56 that generates a tracking error signal 59 corresponding to the deviation of the beam spot on the recording medium from the track center. Furthermore, a lens position deviation signal generation means 10 that generates a lens position deviation signal 15 during a track following operation and a track access operation, an output signal 59 of the tracking error signal generation means 56, and an output signal 15 of the lens position deviation signal generation means 10. A waveform shaping means 20 that generates a track crossing pulse 21 from the track crossing pulse 21, and a track counter 58 that calculates the number of track crossings by measuring the track crossing pulse 21 are provided.

Furthermore, the lens position deviation signal generating means 10 includes a reflecting mirror 1 attached to a tracking actuator (not shown).
1, and a light emitting diode 1 for shining light onto the reflecting mirror 11.
3, a lens position detector 12 capable of determining the position of the lens by sensing the light from the light emitting diode 13 reflected by the reflector 11, and a lens position shift signal 15 generated from the output of the lens position detector 12. differential amplifier 14
It is equipped with

The tracking error signal generating means 56 also includes a photodetector 61 for converting light from the beam splinter 53 into an electrical signal, a differential amplifier 62 for amplifying the output signal of the photodetector 61, and a track-crossing pulse pulse. An F/V converter 65 converts 21 into F-■, and an F/V converter 65 converts the output of the differential amplifier 62 into
A variable band filter 64 is provided for extracting frequency components corresponding to the speed signal output from the V converter 65 and outputting a tracking error signal 59.

The output signal 59 of the tracking error signal generation means 56 and the output signal 15 of the lens position deviation signal generation means 10
As the waveform shaping means 20 for generating the track crossing pulse 21 from the above, a combiner is used.

Next, the operation of this embodiment will be explained.

The light from the light source 51 is focused by the collimating lens 52, becomes a parallel beam, and passes through the beam splitter 53.
The light is focused by the objective lens 54 and applied to the surface of the recording medium 55 . The light hitting the surface of the recording medium 55 exhibits different reflection states between the grooves and on the grooves of the track. and,
The light reflected on the surface of the recording medium 55 is focused by the objective lens 54 and becomes a parallel beam, which is sent to the beam splitter 5.
3, the direction of the light is changed by a photodetector 61, and the light is converted into an electrical signal corresponding to the strength of the light, which is amplified by a differential amplifier 62.

Since it is necessary to detect track crossing pulses in a very wide speed range from 1 [mm/S] to 0.5 [mm/S], the tracking error signal also has a band from near DC to several hundred kHz. If the output signal of the differential amplifier 62 is compared with the waveform shaping means 20 as it is, even the noise component of the signal will appear in the track crossing pulse. Therefore, the variable band filter 64 converts the signal component according to the track crossing speed. It is selectively extracted and used as a tracking error signal 59.

Furthermore, in the lens position shift signal generating means 10, when the position of the lens shifts, the amount of light entering the lens position detector 12 (light from the light emitting diode 13 reflected by the reflecting mirror 11) changes. Therefore, the lens position detector 12 outputs an electric signal corresponding to a change in the position of the lens. Then, the output signal of the lens position detector 12 is subtracted by a differential amplifier 14 to become a lens position deviation signal 15. Therefore, by comparing and shaping the lens position deviation signal 15 and the tracking error signal 59 by a comparator which is the waveform shaping means 20, it is possible to obtain a track crossing pulse 21 in which the influence of offset has been canceled as shown in FIG. .

The track crossing pulse 21 is then input to a track counter 58, which counts the number of track crossings and is used to measure the amount of movement of the head moving mechanism.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a lens position deviation signal generation means for generating a lens position deviation signal during a track following operation and a track access operation, and an output signal of the l.racking error signal generation means and the lens position deviation signal generation means. Since a waveform shaping means is provided that generates a trunk crossing pulse from the output signal of the means, even during high-speed trunk access operation, the number of track crossings can be adjusted without being affected by lens positional deviation or eccentricity of the recording medium. It is possible to provide an unprecedented and excellent optical disc device that can count with high precision and position the track with high precision.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
A waveform diagram showing an example of a tracking error signal and a track crossing pulse in the figure, FIG. 3 is a configuration diagram showing a conventional example, FIG. 4 is a relationship diagram between head movement speed, lens position, and 1-ranking error signal, and FIG. The figure shows the relationship between the amount of lens position deviation and the amount of offset 1~. Figure 6 is a waveform diagram showing an example of the tracking error signal and the 1~ rack crossing pulse when there is no offset. Figure 7 shows the waveform diagram when there is an offset. FIG. 3 is a waveform diagram showing an example of a tracking error signal and a track crossing pulse.

Claims (1)

[Claims] (1) When recording or reproducing information by irradiating light from a light source onto a recording medium through a lens system, in order to count the number of tracks crossed by the head, light reflected from the recording medium is used to illuminate the recording medium. In an optical disc apparatus, the optical disc apparatus is provided with a tracking error signal generating means for generating a tracking error signal corresponding to a deviation of a beam spot from a track center position, wherein the lens system is provided with a tracking error signal that corresponds to a deviation of a beam spot from a track center position, It is characterized by comprising a lens position deviation signal generation means for generating a signal, and a waveform shaping means for generating a track crossing pulse from the output signal of the tracking error signal means and the output signal of the lens position deviation signal generation means. optical disk device.