JPH03152725A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain high speed track access by detecting displacement speed of an objective lens, and controlling a tracking control means so that the objective lens displacement speed goes to nearly zero. CONSTITUTION:A displacing speed of an objective lens 9 in the disk radial direction is detected by differentiating a push-pull signal by a mirror section to acquire a focus error signal at the time of executing track access and a track control means is controlled based on the detection signal. That is, a high pass filter 20 is used to differentiate the push-pull signal to detect a change in a position of the objective lens 9 (displacing speed of objective lens). Then the tracking control means is control so that the objective lens displacement speed goes to nearly zero to increase damping of the tracking control means equivalently to control the displacement of the objective lens 9. Thus, the vibration of the objective lens at the time of executing track access is controlled to attain high speed access.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for optically recording or reproducing information on a large disk recording medium in which servo areas and data areas are arranged alternately along a track. .

In particular, the present invention relates to an optical information recording/reproducing device having a high-speed access function.

[Prior Art] Optical information recording and reproducing devices using optical or magneto-optical signal recording and reproducing methods have been developed. These devices include a focus control means for driving an objective lens in the direction of the disk surface to focus a light beam on the disk, and a focus control means for driving the objective lens in the direction of the disk surface, and a focus control means for driving the objective lens in the direction of the disk surface in order to irradiate the light beam on a concentric or spiral track. It has a tracking control means for driving in a direction orthogonal to the disk, and an optical head moving means for moving the optical head including the dragging control means in the radial direction of the disk for track access operation.

A push-pull method is conventionally known as a method for obtaining a tracking error signal for performing tracking control. In the push-pull method, a tracking error signal is obtained by detecting the imbalance of diffracted light due to deviation of the light beam from a pit or groove using a two-split light receiving element divided in the tangential direction of the track.

In this method, when the objective lens is displaced in the disk radial direction and the optical axis of the light beam and the optical axis of the objective lens are misaligned, the fifth
As shown in the figure, the reflected light from the disk 1 that is incident on the light receiving element 10 is shifted, and an offset occurs in the tracking error signal. Also.

As shown in Figure 6, the disk 1 is tilted (Figure 6 (
a)) or when the light receiving element 10 is misattached (FIG. 6(b)), an offset occurs in the tracking error signal. For this reason, there was a problem in that tracking accuracy deteriorated.

As a means to solve this problem, a sampling servo method was proposed in which the disk is divided into a servo area and a data area, and the servo signal obtained in the servo area is sampled and held to perform continuous servo control. has been done.

In the sampling servo method, as shown in Fig. 2, pits (hereinafter referred to as tracking pits) 34, 35 arranged offset in opposite directions by 1/4 track pitch from the virtual track center are placed on the disk. It is formed. When the irradiation position of the light beam shifts from the center of the track, the amount of reflected light from the pit on the shifted side decreases, and the amount of reflected light from the other pit increases. When the light beam illuminates the center of the track, the amount of light reflected from both track bits is the same. Therefore.

The amount and direction of tracking deviation can be detected by the difference in the amount of reflected light from both tracking pits and the polarity.
Tracking control is performed by controlling the light beam so that the amounts of reflected light from both tracking bits are equal.

In this method, a tracking error signal is obtained by comparing the total amount of light incident on the light receiving element, so the deviation of reflected light on the light receiving element does not pose a problem.

In the servo area, along with tracking bits 34 and 35,
A pit (hereinafter referred to as a clock pit) a6 is formed for obtaining a timing signal St for sampling and recording/reproducing data. Based on the reproduction signal of the clock pits 36 obtained for each servo area, a timing signal St is generated that equally divides the clock pits into a predetermined number. By forming the tracking pits 34 and 35 at positions synchronized with the timing signal St, it is possible to accurately sample the reproduction signal of the tracking bits 34 and 35.

Further, for track counting at the time of track access, the position of the tracking bit 34 changes every 16 tracks.

The focus error signal is obtained in a portion of the mirror between the tracking bit 35 and the clock pit 36, and the error signal obtained in this portion is sampled and held.

When performing track access, turn off the tracking control and use the optical head moving means.

The optical head is moved to the target track, and when the optical head comes to rest, tracking control is performed again.

Generally, the objective lens is supported by a spring or the like. Therefore, when performing a track access operation at high speed, if the optical head is suddenly accelerated or decelerated, force is applied to the objective lens supported by a spring, causing vibration, which causes the optical head to move to the target track position. Even if tracking control is applied, since the objective lens is vibrating, tracking control will not be possible until the vibrations are attenuated.

Access time becomes longer.

As a means to prevent this, a device is provided in which the optical head is provided with a detector that detects the displacement of the objective lens in the radial direction, and the output of this detector constitutes a positioning servo loop for the track control means when accessing a track. This is described in Japanese Patent Application Laid-Open No. 58-26331.

Further, there is an apparatus that detects a current that drives an optical head moving means during track access, and drives a tracking control means based on this current.

It is described in Japanese Patent Application Laid-Open No. 57-94940.

[Problems to be Solved by the Invention] In the prior art described above, the method of attaching a detector to the optical head for detecting the displacement of the objective lens in the radial direction has a problem in that the optical head becomes heavy.

In addition, in the method of detecting the current that drives the optical head moving means, since the tracking control means is controlled in an open loop, sufficient effects cannot be obtained unless adjustments are made to account for variations in the characteristics of the tracking control means. There's a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical information recording and reproducing apparatus that suppresses vibration of an objective lens during track access and enables high-speed access.

[Means to solve the problem]

The above purpose is to detect the displacement speed of the objective lens in the disk radial direction by differentiating the push-pull signal at a part of the mirror to obtain the focus error signal during track access in the sampling servo method, and to use this detection signal as This is achieved by controlling the track control means based on this.

[Operation] As shown in FIG. 5, the push-pull signal outputs a signal with a level corresponding to the displacement of the objective lens, so that the position of the objective lens can be detected. However, as shown in Figure 6, when the disk 1 is tilted (Figure 6 (b)) or when the light receiving element 10 is misplaced (Figure 6 (a)), the push-pull signal level is changes.

Here, since the effects of disk inclination and light-receiving element misalignment appear as changes in the DC level of the push-pull signal, by removing the DC component with a bypass filter, a signal corresponding to changes in the position of the objective lens can be obtained. It will be done. That is, by differentiating the push-pull signal using a bypass filter (differentiation circuit), a change in the position of the objective lens (displacement speed of the objective lens) can be detected. By controlling the tracking control means so that the objective lens displacement speed becomes 18 zero.

Equivalently, the damping of the tracking control means can be increased to suppress the displacement of the objective lens.

Note that, considering the influence of bits and grooves, it is desirable to detect the push-pull signal in a portion of the mirror, and it is necessary to detect the push-pull signal in a portion that is not affected by the recording signal. Therefore, in the sample servo method, the displacement speed of the objective lens is detected by a push-pull signal from a part of the mirror to obtain a focus error signal, and by controlling the tracking control means with this signal, the objective lens is displacement can be suppressed.

In the present invention, a light receiving element is used to detect the displacement speed of the objective lens, and since the light receiving element is generally small and lightweight, the weight of the optical head increases only slightly.

In particular, if it is used also as a light receiving element for tracking error detection and focus error detection, no increase in weight will occur.

In addition, since control is performed while detecting the displacement speed of the objective lens with the light receiving element, it is a closed loop control.

It is possible to deal with variations in the tracking control means.

As described above, by suppressing the displacement of the objective lens during track access, the vibration of the objective lens is suppressed, thereby enabling high-speed access.

〔Example〕

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

FIG. 1 shows the configuration of an embodiment of the present invention.

FIG. 2 shows signal waveforms at each part of FIG. 1.

In FIG. 1, the motor 2 is controlled by a motor servo circuit 3 so that the angular velocity of the disk I is constant.

Recorded data is input to the modulation circuit 4 from, for example, a computer or the like via an interface. The input data is subjected to predetermined modulation in the modulation circuit 4 and then output to the laser drive circuit 5, which drives the laser diode 6 and converts it into the intensity of the light beam. The light beam emitted from the laser diode 6 is irradiated onto the discos L via a collimator lens 7, a beam splitter 8°, and an objective lens 9.

The reflectance of the recording film on the disk 1 changes depending on the strength of the irradiated light beam, and data is recorded because this change in reflectance remains even after the light beam has passed.

During reproduction, the light intensity of the light beam output from the laser diode 6 is set to a predetermined value such that the reflectance of the disc 1 does not change. The light beam irradiated onto the disk 1 is reflected by the recording film and enters the light receiving element 10 via the objective lens 9 and the beam splitter 8, and changes in the amount of reflected light due to changes in the reflectance of the recording film of the disk are converted into electrical signals. Convert.

The output of the light receiving element 10 is sent to the preamplifier 13, and each light receiving area (10-A, 10-B, 10-C) is sent to the preamplifier 13.

1O-D), the reproduced signal S a (S a =
A+B+C+D), Sf (Sf= (A+C)-(B
+D)), Sp (Sp= (A+D)-(B+C))
is generated.

The reproduced signal Sf is transmitted through a sample hold circuit (S/H circuit)
14, the sample pulse SP1 samples and holds the reproduced signal Sf at a portion of the mirror between the tracking pit 35 and the clock pit 36, and outputs it to the focus servo circuit 15 as a focus error signal. The focus servo circuit 15 generates focus servo control (f1) based on the focus error signal, and this signal is sent to the optical head 11, which controls the focus by driving a focus control means (not shown). will be carried out.

On the other hand, the reproduced signal Sa is input to the peak value detection circuit 16° S/H circuits 21, 22, and 23 and the demodulation circuit 20.

The peak value detection circuit 16 detects the peak value of the reproduced signal Sa, and the unique pattern detection circuit 17 detects a pit pattern having a unique interval given only between the tracking pits 35 and the clock pits 36, and detects the clock pits. 36 is detected.

This detection output is sent to the pulse generation circuit 1 via the delay circuit 18.
Sent to 9th. In the pulse generation circuit 19.

Based on the detection output obtained by the unique pattern detection circuit 17, timing signals St, sample pulses SPI, SP2 . Generates SP3°SF3.

The demodulation circuit 20 converts the timing signal S from the reproduced signal Sa.
Demodulation is performed based on t, and reproduced data is output.

In the S/H circuits 21, 22, and 23, each sample pulse SP
2. SP3. SP4 samples and holds the input reproduction signal Sa. The outputs of the S/H circuits 21 and 22 are compared in level by a comparator 25. This comparison output is input to the seek circuit 33 as a track count signal at the time of access, and is also input to the multiplexer 26. At multiplexer 26.

Among the signals from the S/H circuits 21 and 22, the signal with a higher level is selected and output to the subtraction circuit 27.

In the subtraction circuit 27, the signal from the multiplexer 26 and S
The difference between the signals from the /H circuit 23 is taken and sent to the tracking servo circuit 28 and the seek circuit 3 as a tracking error signal.
Output to 3.

The tracking servo circuit 28 generates a tracking servo control signal based on this tracking error signal, and outputs this signal to the multiplexer 31.

Further, the seek circuit 33 controls the optical head moving means 12 based on the output of the comparator 25 and the output of the subtraction circuit 22.
and controls the movement of the optical head 11 during track access.

The reproduction signal Sp is input to the S/H circuit 24, and the reproduction signal Sp at a portion of the mirror between the tracking pit 35 and the clock pit 36 is sampled and held by the sample pulse SPI. The DC component is removed from the output of the S/H circuit 24 by the differential characteristics of the bypass filter (PF) 29, and the output is sent to the lens speed control circuit 30 as a signal indicating the change in the position of the objective lens, that is, the displacement speed of the objective lens.
is input. In the lens speed control circuit 30, HP F
A lens speed control signal that makes the objective lens displacement speed approximately zero is generated based on the output of 29, and this signal is output to the multiplexer 31.

The multiplexer 31 uses the control signal from the seek circuit 33 to control the lens speed control circuit 30 during track access.
A lens speed control signal output from the drive circuit 32 is output from the drive circuit 32 . The output of the drive circuit 32 is sent to the optical head 11,
By driving tracking control means, not shown here.

Equivalently, the damping of the tracking control means is increased to suppress the displacement of the objective lens.

In addition, at times other than track access, the tracking servo control signal output from the tracking servo circuit 28 is selected by the multiplexer 31, and this signal is sent to the optical head 11 via the drive circuit 32 to drive the tracking control means. Tracking is controlled by this.

Other embodiments of the present invention are shown in FIGS. 3 and 4.

FIG. 3 shows an embodiment in the case of a magneto-optical disk, in which the same functional parts as in FIG. 1 are given the same numbers and explanations will be omitted unless particularly necessary.

In magneto-optical disks, the effect of recorded data is on the reproduced signal Sp.
Therefore, a signal indicating the displacement speed of the objective lens is generated from the reproduced signal sp in the mirror section of the data area.

In the case of a magneto-optical disk, when the intensity of the light beam irradiated onto the magneto-optical disk 1 is increased, a magnetic circuit (not shown) generates a magnetic field on the disk surface, which causes the recording film to be The direction of magnetization of the recording film is determined, and data is recorded by maintaining the direction of magnetization of the recording film even after the light beam passes through it. During reproduction, the light intensity of the light beam is set to a predetermined value that does not change the direction of magnetization of the recording film, and the light beam is irradiated onto the disk 1 and reflected by the light receiving element 10°1.
0' and converts changes in the polarization of reflected light due to changes in the magnetization direction of the recording film into electrical signals.

The reason why there are two sets of light receiving elements 10 and 10' is that there are two types of polarized light and each of them is detected. As described later, the reproduced data is obtained from the difference in the outputs of both light-receiving elements, but the signal used for feIJ is the same as for optical discs, and can be obtained from the output of either one of the two light-receiving elements, or from the output of both light-receiving elements. It may also be obtained using the output of the element.

The output of the light receiving elements 10 and 10' is sent to the preamplifier 13, and the light receiving area (10-A) of each light receiving element is sent to the preamplifier 13.

10-B, 10-C, 10-D, 10'-A'10'
-B'10'-C',10'-D') from the output of the reproduced signal Sa (Sa=A+B+C+D+A'+B'
+C'+D' ), Sf (Sf= (
A+A'+C+C')-(B+B'+D+
D')).

Sp (SP= (A+A'+D+D')-
(n+B'+C+C')), Sd (Sd=
(A+B+C+D)-(A'+B'+C'10D'
)) is generated.

The reproduced signal Sp is input to the S/H circuit 24.

The reproduced signal Sp in the mirror section of the data area is sampled and held by the sample pulse SP5. S/H
The DC component of the output of the circuit 24 is removed by the differential characteristics of a bypass filter (HPF) 29, and the output is input to the lens speed control circuit 30 as a signal indicating a change in the position of the objective lens, that is, a displacement speed of the objective lens. The lens speed control circuit 30 generates a lens speed control signal such that the objective lens displacement speed becomes approximately zero based on the output of the HPF 29,
This signal is output to multiplexer 31.

The multiplexer 31 uses the control signal of the seek circuit 33 to control the lens speed control circuit H13 during track access.
A lens speed control signal outputted from 0 is outputted to the drive circuit 32. l! The output of the dynamic circuit 32 is sent to the optical head 11, and by driving a tracking control means (not shown), the damping of the tracking control means is equivalently increased and the displacement of the objective lens is suppressed.

In addition, at times other than track access, the tracking servo control signal output from the tracking servo circuit 28 is selected by the multiplexer 31, and this signal is sent to the optical head 11 via the opening circuit 32 to drive the tracking control means. Tracking is controlled by this.

On the other hand, the reproduced signal Sd indicating the change in the polarization state of one reflected light is
The demodulation circuit 20 manually demodulates the signal based on the timing signal St, and outputs reproduced data.

In the above embodiment, the tracking bit 35 and clock bit 3 are used as positions for obtaining push-pull signals.
It is clear that the mirror part 1 between the tracking bits 34 and 35 may be used as the mirror part 1 between the tracking bits 34 and 35, or the mirror part in the data area of the magneto-optical disk.

Further, in the above embodiments, a sample servo type optical disk has been described, but it is obvious that the optical disk is not limited to this, and any disk having a mirror portion may be used. Furthermore, it is clear that the recording medium is not limited to a disk-shaped recording medium, but may also be a card-shaped recording medium.

[Effects of the Invention] As described above, according to the present invention, by detecting the displacement speed of the objective lens and controlling the tracking control means so that the objective lens displacement speed becomes approximately zero, Since the damping of the tracking control means can be increased and the displacement of the objective lens can be suppressed, high-speed track access is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a waveform diagram showing signal timing of the embodiment of FIG. 1, and FIG.
FIG. 4 is a block diagram showing the second embodiment of the present invention, FIG. 4 is a waveform diagram showing the signal timing of the embodiment of FIG. 3, and FIG.
The figure is an explanatory diagram showing the position of the light beam on the light receiving element when the objective lens is displaced. Figure 6 shows the position of the light beam on the light receiving element when the light receiving element is mounted out of position and when the disk is tilted. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 1... Disk, 9... Objective lens, 11... Optical head, 13... Preamplifier, 24... S/H circuit, 3016. Lens speed control circuit, 31... multiplexer. 32... Drive circuit. Disk 10 Moving I8 Light beam person J Yuhe d Ward 1 Teace 7 10 Light receiving system 1 small item L box included

Claims (1)

[Claims] 1. An optical system including an objective lens for condensing a light beam from a light source onto a recording medium, and two or more optical systems capable of detecting a deviation in the distribution of a reflected light image from the recording medium. a light receiving element having an element area; a tracking control means for driving the objective lens in a direction across the tracks of the recording medium to perform tracking; and an optical head including the optical system, the light receiving element, and the tracking control means for moving the optical head to the track An optical information recording/reproducing apparatus comprising: an optical head moving means that moves in a direction across the track to access a track. means for detecting the displacement of the objective lens in the direction across the track using the light reception output of the light receiving element; means for detecting the displacement speed of the objective lens in the direction across the track from the detected displacement; means for generating a signal that makes the displacement speed of the objective lens approximately zero based on the speed determined by the optical head; and the tracking control so that the displacement speed of the objective lens is approximately zero when the optical head accesses a track based on the generated signal. An optical information recording/reproducing device characterized by comprising a driving means for driving the means. 2. On a disk-shaped information recording and reproducing medium in which arbitrary information recording and reproducing areas and servo information reproducing areas are arranged alternately on the same track, and a servo signal is prerecorded in the servo information reproducing area, An optical system including an objective lens for condensing a light beam and a dividing boundary for detecting changes in reflected light from the information recording/reproducing medium are divided into four in the tangential direction and perpendicular direction of the track on the information recording/reproducing medium. a tracking control means for driving the objective lens in the radial direction of the information recording/reproducing medium to perform tracking; and an optical head including the optical system, the light receiving element, and the tracking control means for controlling the information recording/reproducing medium. an optical head moving means for moving the medium in the radial direction; a first arithmetic circuit that calculates the sum of the outputs of the four-part light receiving element and outputs a first reproduction signal;
a timing signal generation circuit that generates a timing signal based on the first reproduction signal obtained through the divided light receiving element; and a timing signal generation circuit that generates the four divided light receiving element in the servo information reproduction area based on the output of the timing signal generation circuit. In an optical information recording and reproducing apparatus, the optical information recording and reproducing apparatus includes a tracking error detection circuit that detects a displacement error of the light beam with respect to the track by sampling and holding a first reproduction signal obtained through the track of the quadrant light receiving element. a second arithmetic circuit that calculates a difference between the outputs of the light-receiving elements divided in the tangential direction and outputs a second reproduction signal; and a second calculation circuit that calculates the difference between the outputs of the light receiving elements divided in the tangential direction and outputs a second reproduction signal; A sample and hold circuit samples and holds the second reproduction signal obtained through the light receiving element, and the displacement speed of the objective lens in the radial direction of the information recording and reproduction medium is determined by differentiating the output of the sample and hold circuit. a lens displacement speed detection circuit for detecting the above, and a lens displacement speed detection circuit that drives the tracking control means based on the output of the tracking error detection circuit during recording and reproduction, and drives the tracking control means based on the output of the lens displacement speed detection circuit during track access. An optical information recording/reproducing device comprising: a driving means for driving. 3. A light source is placed on a disc-shaped magneto-optical information recording and reproducing medium in which arbitrary information recording and reproducing areas and servo information reproducing areas are arranged alternately on the same track, and a servo signal is prerecorded in the servo information reproducing area. An optical system including an objective lens for condensing a light beam from the magneto-optical information recording and reproducing medium, and a division boundary for detecting two types of polarized light of the reflected light from the magneto-optical information recording and reproducing medium are located on the track on the recording and reproducing medium. two light receiving elements divided into four in a tangential direction and a vertical direction, a tracking control means for driving the objective lens in a radial direction of the recording/reproducing medium to perform tracking, the optical system, the light receiving element, and tracking control. an optical head moving means for moving an optical head including means in the radial direction of the recording/reproducing medium; and a first arithmetic circuit for calculating the sum of the outputs of the two light receiving elements and outputting a first reproduction signal. and a timing signal generation circuit that generates a timing signal based on the first reproduction signal obtained from the arbitrary information recording and reproduction area via the two light receiving elements, and a timing signal generation circuit that generates a timing signal based on the output of the timing signal generation circuit. An optical system comprising a tracking error detection circuit that detects a displacement error of the light beam with respect to the track by sampling and holding the first reproduction signal obtained from the servo information reproduction area via the two light receiving elements. a second arithmetic circuit that calculates a difference between the outputs of the light-receiving elements divided in the track tangential direction in one or both of the two light-receiving elements and outputs a second reproduction signal; and a sample hold for sampling and holding the second reproduction signal obtained through either or both of the two light receiving elements in the arbitrary information recording and reproduction area based on the output of the timing signal generation circuit. a lens displacement speed detection circuit that detects the displacement speed of the objective lens in the radial direction of the information recording/reproducing medium by differentiating the output of the sample/hold circuit; and an output of the tracking error detection circuit during recording/reproduction. an optical information recording and reproducing apparatus, comprising: a drive means for driving the tracking control means based on the output of the lens displacement speed detection circuit when accessing a track; .