JPH07244859A - Method for jumping track and multi-beam optical head - Google Patents

Abstract

PURPOSE:To jump a track without leaving the track without being scanned, by continuing reading of a precedent data track and reading a data track which is different from the precedent data track and not yet scanned. CONSTITUTION:A condensed spot 8 scans an (n+1)th data track 7 and a condensed spot 9 scans an (n+2)th data track. The spot 8 is then let to jump to an (n-42)th track. A jump pulse from a jump pulse generator circuit 32 is input to a drive circuit 30 through an adder 28. As a result, the drive circuit 30 drives a galvano mirror 18 in a T1 direction, so that the spot 8 is let to jump to the (n+2)th track. When tone jumping is finished, the generator circuit 32 stops operating, and the spot 8 scans the (n+2)th track. During this time, the condensed spot 9 performs a general tracking control. Therefore, data tracks are never left unscanned because of jumping of tracks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information reproducing apparatus for reading information in parallel from information tracks formed in a single spiral shape on an information recording medium, and more particularly to recording information continuously on the information tracks. The present invention relates to a method for jumping tracks so that the read data has no omission when reading the read data, and a multi-beam optical head for performing track jumping using this method.

[0002]

2. Description of the Related Art FIG. 31 shows, for example, Japanese Patent Laid-Open No. 59-659.
32 is a perspective view showing a configuration of a conventional multi-beam optical head described in Japanese Patent Publication No. 48, and FIG. 32 schematically shows an optical disk having a normal single spiral information track. 33 to 40 are views for explaining an example of a conventional track jumping method using a conventional multi-beam optical head.

In FIG. 31, reference numeral 1 denotes a light emitting source such as a semiconductor laser array which emits a plurality of light beams, and Japanese Patent Laid-Open No. 59-65948 discloses a semiconductor laser array which emits three light beams. However, in FIG. 31, for convenience, a semiconductor laser array that emits two light beams is shown. 2 is a collimator lens for converting the light beam emitted from the light emitting source 1 into parallel light, 4 is a launching mirror, 5 is an objective lens as a focusing means, 6 is an information recording medium such as an optical disk, and 7 is an information recording medium 6. Shows a portion of the information track formed in a single spiral,
Reference numerals 8 and 9 denote two focused spots focused and irradiated on the information track 7.

Track jumping is usually performed by a tracking actuator mounted on the objective lens 5 (see FIG. 3).
1 is not shown), and the objective lens 5 moves in the T direction in FIG. 31 by one cycle (usually 1.6 μm) of the information track 7. Along with this, the two converging spots 8 and 9 are also set to 1 of the information track 7.
It moves in the T direction by a period (usually 1.6 μm).

FIG. 32 schematically shows an information recording medium 6 having an information track 7 formed in a single spiral shape on its upper surface, and two converging spots 8 and 9 are shown. There is. The area 10 surrounded by a dotted line in FIG.
Is enlarged and displayed in FIGS. 33 to 40. The single spiral curve in FIG. 32 and the solid line shown in FIGS. 33 to 40 are the information tracks 7, and in the area 10, n, n + 1, n + 2, n + 3, n + 4, n + 5 are sequentially arranged from the top.
The numbers are given as (n: integer). In FIG. 32, the start position of each numbered information track 7 is indicated by a dotted straight line and a number. Also, the length of the information track given one number is one round, but since the information track has a single spiral shape, all the information tracks are connected.

Next, a track jumping method for reading data continuously recorded on a single spiral information track will be described with reference to FIGS. 33 to 40. 33 to 40, the two focused spots 8 and 9 are shown as S1 and S2. In FIG. 33, time t = T1
In the figure, the two focused spots 8 and 9 are on the n-th and (n + 1) -th information tracks, respectively, and the state immediately before the track jumping for one line is shown. The dotted line represents the locus of the focused spot 8 on the information track, and the alternate long and short dash line represents the locus of the focused spot 9 on the information track.

FIG. 34 shows the states of the focused spots 8 and 9 immediately after the first track jumping. The focused spot 8 is the (n + 1) th information track and the focused spot 9 is the (n + 2) th information track. Have moved to the information track. Normally, the time of about 1 millisecond required for track jumping and the time to complete resynchronization after jumping,
The reading of data from the information track will be interrupted. Since the time Δj during which the focused spots 8 and 9 are diagonally moving in FIG. 34 is the time required for track jumping, the time t in FIG. 34 is (T1 + Δj).

FIG. 35 shows the positions of the focused spots 8 and 9 when the time Δa has passed after the completion of jumping.
The time t in FIG. 35 is (T1 + Δj + Δa).

FIG. 36 shows a state in which the information recording medium makes one revolution and the two converging spots 8 and 9 have returned to the rotational positions where the track jumping was performed last time. Letting Tr be the time required for the information recording medium to make one rotation, FIG.
At time t is (T1 + Tr), the focused spot 8 is the (n + 2) th information track, and the focused spot 9 is (n
It is on the +3) th information track.

FIG. 37 shows a slight time Δ from the state of FIG.
After 1 has elapsed, the light spot 8 is rescanned to some extent on the portion where the light spot 9 was scanned one revolution before. The time t in FIG. 37 is (T1 + Tr + Δ1) = T2, and the second track jumping can be started from this state.

FIG. 38 shows the position of the focused spot at time t = (T2 + Δj) immediately after the end of the second track jumping, where the focused spot 8 is (n + 3).
The focused spot 9 is moved to the (n + 4) th information track on the th information track.

FIG. 39 shows that after the second jumping is completed,
It shows two focused spot positions after a short time Δb has passed.

FIG. 40 shows a state in which the information recording medium is further strengthened by one revolution from the state of FIG. 39, and the two converging spots 8 and 9 have returned to the vicinity of the rotational position where the previous track jumping was performed. T2 + Tr + Δ2) = T3. At this time, since the focused spot 8 has rescanned a part of the portion previously scanned by the focused spot 9, it is in a state immediately before starting the third track jumping.

For the track jumping method of the multi-beam optical head, see "SPIE Procee".
ding Vol. 1316 (1990) "No. 58-6
“Digital Video Recorder” on page 4
ding System Using Multi-B
EAM Magneto-Optical DiskD
Live (K. Yoshihara et al.).

[0015]

Increasing the data reading speed is one of the major technical problems in optical disk devices and magnetic disk devices, and technical development for this purpose is being actively pursued. For example, CD-ROM
The device is considered as one of the promising media in the future of multimedia, but the problem is that the reproduction of interactive software including image information occurs at normal speed.

Therefore, the CD-ROM is doubled or 4 times larger than usual.
A device that rotates at twice the speed has been developed. For example, a current CD-ROM has a speed four times as fast as the normal CD-ROM (about 80 at the outermost circumference).
When rotated at 0 rpm and about 2000 rpm at the innermost circumference, data can be read out at about 4.8 megabits per second.

However, if an attempt is made to increase the data reading speed with an apparatus using a single beam optical head,
The only way to increase the rotation speed of the CD-ROM is
In this case, the surface wobbling and the acceleration of eccentricity increase as the rotation speed of the optical disk increases. Along with this, it is necessary to improve the tracking performance of the objective lens actuator of the optical head, and for that purpose, it is necessary to improve the sensitivity of the objective lens actuator and to improve the characteristics of the servo circuit.

Further, since the frequency of the data to be handled also becomes high, the frequency band of the head amplifier for amplifying the signal current taken out from the optical head with low noise is proportionally increased, and the analog signal output by the head amplifier is processed. High speed is also required for the waveform equalization / shaping / discrimination circuit, and the spindle motor must be strengthened to rotate the CD-ROM at high speed.

Considering the above conditions, in the present technology, the speed is 8 times as fast as the normal speed (about 1600 rp at the outermost circumference).
m, the innermost circumference is about 4000 rpm) seems to be the limit (the data reading speed at this time is about 9.6 megabits). Therefore, in order to realize a higher data reading speed, a multi-beam optical head that can use a plurality of focused spots for reading data emerges as an effective means.

However, since the conventional track jumping method is performed as described above, an information track is formed from an information recording medium in which information tracks are formed in a single spiral shape such as a CD-ROM using a multi-beam optical head. When reading the data continuously recorded on the upper side, there is a problem that the read data is lost when the track jump is performed.

How to cause this problem will be described below with reference to FIGS. 33 to 40. In FIG. 33 to FIG. 40, two focused spots 8 and 9 are on adjacent information tracks, and each time the information recording medium 6 makes one revolution, track jumping for one information track is performed to continuously perform The state of track jumping when reading data from the information recording medium 6 is shown in FIG.
Here, assuming a situation where continuous data reading is started from the (n + 1) th information track, FIG.
At 0, the portion (F1) in which the locus of the focused spot on the (n + 1) th and (n + 3) th information tracks is stagnant
And F3). This is because the track jumping requires a time of about several milliseconds, so that the information recording medium 6 is in the meantime.
Is caused by the movement of. If continuous reading of data continues, a similar portion where the trace of the focused spot is interrupted will occur in every two information tracks thereafter.

Next, let us consider whether or not the data loss as described above can be corrected. In the conventional track jumping method, the amount of data loss due to track jumping is proportional to the product of the data read speed and the time required for jumping. Now, considering the case where data is read out at 5 Mbits / sec for one information track, it takes 5 ms during 1 ms of track jumping.
Data of 000 bits will be lost, and data of 10,000 bits will be lost in 2 milliseconds.

With a CD (compact disc) that employs a correction code that has been subjected to an interleave operation, up to about 4000 bits of continuous error in data can be completely corrected, but when 5000 bits or 10000 bits is reached, complete correction is possible. Becomes impossible. 512 bytes * 8 = 40 for normal 90mm and 130mm diameter optical disks
Data of 96 bits or 1024 bytes * 8 = 8192 bits is recorded in one sector. In case of 1024 bytes / sector, maximum 8 for data in 1 sector
Since 0 * 8 = 640 bit error correction is possible, 5
A correction for the loss of 000-bit continuous data is clearly impossible.

Furthermore, the data cannot be read out immediately after the jumping, and it takes time for the synchronization pull-in. Therefore, until the synchronization pull-in is completed,
The loss of read data will continue to occur. Figure 4
At 0, R1 and R3 indicate a missing portion of data that occurs during the time from the completion of track jumping to the completion of synchronization pull-in.

The present invention has been made to solve the above problems, and a first object thereof is to read data in parallel from an information recording medium having information tracks formed in a single spiral shape. In doing so, it is to obtain a track jumping method in which no loss of read data occurs.

A second object is that in a multi-beam head for reading data from an information recording medium having an information track formed in a single spiral shape by using a plurality of converging spots, loss of read data does not occur. To get the track jumping method.

A third object is to obtain a multi-beam optical head capable of track jumping so that all information tracks can be scanned in the multi-beam head.

A fourth object is to obtain a multi-beam optical head capable of increasing the data reading speed when reading the data continuously recorded on the information track using the multi-beam head. .

[0029]

In the track jumping method of an information reproducing apparatus according to the present invention, data reading from the most preceding information track continues, and the rest is an unscanned information track different from the previous information track. It is designed to perform a track jump as if read from.

Further, the remaining condensing spots other than the most preceding converging spot are made to jump to the information track even when unscanned, which is different from the information track before the track jump.

Further, the remaining focused spots other than the most focused focused spot are made to jump to the information track at a position symmetrical with respect to the focused spot.

The multi-beam optical head according to the present invention comprises a track deviation correcting means for independently correcting the track deviation of each focused spot, a tracking error signal generating means for each focused spot, and a jump pulse generating circuit. When the track jump is performed, the output of the tracking error signal generation means is kept added to the track deviation correction means of the most preceding focused spot, and the track deviation correction of the remaining focused spots excluding this is performed. The output of the jump pulse generating circuit is applied to the means.

Further, a data synthesizing means for synthesizing the data read by each of the plurality of focused spots into a series of continuous data is provided.

[0034]

According to the track jumping method of the present invention, only the reading from the most preceding information track is continued, and the rest is jumped from the unscanned information track different from the previous information track. Thus, all parts of a single spiral information track can be scanned.

Further, since the remaining focused spots except the most preceding focused spot are made to jump to the unscanned information track different from the information track before the track jump, all the parts of the single spiral information track. Can be scanned with a focused spot.

Furthermore, when track jumping is performed on the remaining focused spots excluding the most advanced focused spot, the remaining focused spot is jumped to an information track located at a position symmetrical to the most focused spot. As a result, all portions of the single spiral information track can be scanned with the focused spot.

According to the multi-beam optical head according to the present invention, the output of the jump pulse generating circuit is added to the track deviation correction means for the focused spots other than the focused lead spot. The remaining focused spot can be jumped to an unscanned information track different from the information track before the track jump.

Further, the data synthesizing means synthesizes the data read by the respective focused spots and converts them into a series of continuous data.

[0039]

【Example】

Example 1. 1 to 8 are explanatory views showing a track jumping method according to an embodiment of the present invention, in which the position of a focused spot is shown corresponding to time. The area shown in FIGS. 1 to 8 is an enlarged display of the area 10 in the information recording medium 6 shown in FIG. 32, as in the conventional example.
The number of focused spots is also two. S in FIGS. 1 to 8
1 and S2 are 2 as in the conventional example shown in FIGS.
These are two focused spots 8 and 9. In addition, the solid lines in FIGS. 1 to 8 represent the information track 7, and in order from the top,
The numbers n, n + 1, n + 2, n + 3, and n + 4 are also given, as in the conventional example.

In the first embodiment, every time the information recording medium rotates slightly over one revolution, the preceding focused spot is not jump-tracked but the trailing focused spot is jumped forward by two information tracks. Is the way. Hereinafter, the operation of this embodiment will be described in detail with reference to FIGS.

In FIG. 1, at time t = T1, the two focused spots 8 and 9 are the nth information track, (n
It is on the +1) th information track and shows the state immediately before the first track jumping. here,
The dotted line represents the locus of the focused spot 8 on the information track, and the alternate long and short dash line represents the locus of the focused spot 9 on the information track.

FIG. 2 shows the positions of the focused spots 8 and 9 immediately after the first track jumping is performed.
1 moves from the nth to (n + 2) th information track, and S2 remains on the (n + 1) th information track without performing track jumping. The time t in FIG. 2 is (T1 + Δj), and Δj indicates the time required for track jumping.

FIG. 3 shows the focused spot 8 after jumping,
9 and the time t in FIG. 3 is (T1 + Δj
+ Δa) (Δa is a minute time as compared with the time required for the information recording medium 6 to rotate once).

FIG. 4 shows a state in which the information recording medium 6 has rotated once and the two converging spots 8 and 9 have returned to the rotational positions where the track jumping was performed last time, and the time t in FIG. T1 + Tr) (Tr is the time for the information recording medium 6 to rotate once). At time t = (T1 + Tr), the focused spot 8 is on the (n + 3) th information track and the focused spot 9 is on the (n + 2) th information track.

FIG. 5 shows a state in which the focused spot 9 has rescanned a part of the portion previously scanned by the focused spot 8 after a short time Δ1 has elapsed from the state of FIG. Figure 5
At time t, (T1 + Tr + Δ1) = T2, and the second track jumping starts from this state.

FIG. 6 shows the position of the focused spot at time t = (T2 + Δj) immediately after the end of the second track jumping, and the focused spot 8 remains as it is.
The focused spot 9 is moved from the (n + 2) th information track to the (n + 4) th information track.

FIG. 7 shows a time t = T2 + Δj + Δb when Δb (Δb is a minute time compared to the time required for the information recording medium 6 to make one rotation) has elapsed from the second track jumping.
Are the positions of the two focused spots at.

FIG. 8 shows a state in which the information recording medium 6 is strengthened once from the state of FIG. 5 and the two focused spots 8 and 9 are returned to the vicinity of the rotational position where the previous track jumping was performed. The time t in FIG. 8 is (T2 + Tr + Δ2) = T
3 (Δ2 is a minute time compared to the time when the information recording medium 6 makes one rotation), and the focused spot 8 rescans a part of the portion previously scanned by the focused spot 9. . Therefore, as can be easily seen from the locus of the focused spot shown in FIG. 8, in the first embodiment, there is no omission in the scanning of the information track.

As described above, the information recording medium is about 2 in FIGS.
Although the method of track jumping until rotation is described, in order to continue the scanning of the information track, one of the focused spots 8 and 9 is added every time the rotation of the information recording medium slightly exceeds one rotation. The two tracks will be alternately jumped forward.

FIG. 9 is a diagram showing two (n + 1) th to mth information tracks (m ≧ n + m) according to the track jumping method described above.
This is a flow chart summarizing the procedure for completely scanning 2).

Example 2. 1 to 8 show the case where there are two focused spots, FIGS. 10 to 17 show the track jumping method when there are three focused spots. 10 to 17 correspond to FIGS. 1 to 8, respectively. Here, S3 in the figure represents the third focused spot 3, and the three focused spots 3, 8 and 9 are on information tracks adjacent to each other. 3 focused spots
The track jumping in the case of the number of pieces is basically the same as that in the case of two focused spots, and every time the rotation of the information recording medium slightly exceeds one rotation, the preceding focused spot is not subjected to the track jumping, The two converging spots that follow are jumped forward.

First, a brief description of FIGS. 10 to 17 will be given. FIG. 10 (t = T1) shows the state of the focused spot immediately before the first track jumping, and FIG. 11 (t = T1).
+ Δj) is the state of the focused spot immediately after the first track jumping, FIG. 12 (t = T1 + Δj + Δ)
13A shows the state of the focused spot when a short time Δa has passed from the first track jumping, and FIG.
T1 + Tr) is the state when the information recording medium makes one rotation after the first track jumping is started, as shown in FIG.
= T1 + Tr + Δ1 = T2), after a short time Δ1 has passed from the state of FIG. 13, the focused spots 3 and 9 rescan a part of the portion previously scanned by the focused spots 8 and 9, and the second time This is the state just before the track jumping starts.

Further, FIG. 15 (t = T2 + Δj) shows the state of the focused spot immediately after the second track jumping is finished, and FIG. 16 (t = T2 + Δj + Δb) shows a short time Δb after the second track jumping. 17 (t = T2 + Tr + Δ2 =
In T3), the information recording medium 6 is forced to make one rotation from the state of FIG. 14 to reach the position where the focused spot slightly exceeds the rotational position where the track jumping was performed last time, and the state immediately before the third track jumping starts. Shows. In FIG. 17, the focused spots 8 and 9 rescan a part of the portions previously scanned by the focused spots 3 and 9, respectively.

As can be seen from FIGS. 10 and 11 which show the states immediately before and after the first track jumping, the preceding focused spot 3 does not move from the (n + 2) th information track and is collected. The light spot 8 is subjected to track jumping for four lines from the nth information track to the (n + 4) th information track, and the focused spot 9 is (n + 1).
Two tracks are jumped from the information track n to the (n + 3) th information track. Alternatively, as can be seen from FIGS. 14 and 15 showing the states immediately before and immediately after the second track jumping, the preceding focused spot 8 does not move from the (n + 5) th information track, The spot 9 performs two track jumping from the (n + 4) th information track to the (n + 6) th information track, and the condensing spot 3 has four lines from the (n + 3) th information track to the (n + 7) th information track. Do minute track jumping.

In the conventional example, the information track has a portion where the focused spot cannot be scanned due to track jumping, but as can be easily seen from FIG.
In this case, there is no omission in the scanning of the information track.

As described above, the method of track jumping until the information recording medium makes about two rotations has been described with reference to FIGS. 10 to 17. However, in order to further continue the information track scanning, Every time the rotation slightly exceeds one rotation, track jumping of the following two focused spots among the focused spots 3, 8 and 9 is repeated. At this time, track jumping for two lines is performed on the side closer to the preceding focused spot, and four tracks are jumped on the side farther from the other focused spot on the other side.

By the way, in the first embodiment, the focused spot is 2
In the second embodiment, the case where the number of focused spots is 3 has been described, but it is obvious that the present track jumping method can be easily realized even when the number of focused spots is 4 or more.

Further, in the second embodiment, the focused spot to be jumped is moved to the information track at a position symmetrical with respect to the focused spot not to be jumped, but this is not always necessary. For example, FIGS.
In, the focused spot 8 may be jumped from the nth information track to the (n + 3) th information track, and the focused spot 9 may be jumped from the (n + 1) th information track to the (n + 4) th information track. . In short, each time the rotation of the information recording medium slightly exceeds one rotation, the preceding focused spot is not jump-tracked, but the two focused spots following are jumped to the unscanned information track in front. .

Furthermore, in the first and second embodiments, the case where the information recording medium is an optical disk has been described, but it goes without saying that the present invention can also be applied to the case where a magnetic disk has information tracks formed in a single spiral shape. In the case of a magnetic disk, the reading magnetic head itself is driven for track jumping instead of the focused spot.

Example 3. FIG. 18 shows an optical path system of the optical head capable of performing the track jumping described in the first embodiment. Here, the case where there are two focused spots is shown. In FIG. 18, 11 and 12 are light emission sources such as semiconductor lasers, 13 and 14 are collimator lenses for converting divergent light fluxes from the light emission sources 11 and 12, and 15 and 16 are parallel light fluxes from the collimator lenses 13 and 14. Is a beam splitter for directing the reflected light from the information recording medium 6 to a two-split photodetector described later. Reference numerals 17 and 18 are track deviation correcting means, and a galvanometer mirror is used in this embodiment. Reference numeral 19 is a beam combining mirror for obtaining two parallel light beams propagating in substantially the same direction by changing the traveling direction of one of the two parallel light beams from the Galvano mirrors 17 and 18. The components 5, 6, 7, 8 and 9 are the same as those of the conventional example shown in FIG. 31, and the two parallel light beams passing through the beam combining mirror 19 are condensed by the objective lens 5 which is a focusing means. Two focused spots 8 and 9 are formed on the information track 7 of the information recording medium 6.

Next, reference numerals 20 and 21 are focusing lenses for focusing the reflected light from the information recording medium 6 on a two-divided photodetector described later, and 22 and 23 are two-divided photodetectors.
Reference numeral 24 is a differential amplifier for obtaining the differential output of the two-split photodetector 22, and 25 is a differential amplifier for obtaining the differential output of the two-split photodetector 23. Here, the two-part photodetector 2
2, a set of differential amplifiers 24, and a two-part photodetector 23,
Each set of differential amplifiers 25 constitutes a tracking error signal generating means.

26 and 27 are sample and hold circuits, 2
Reference numerals 8 and 29 are adders, and reference numerals 30 and 31 are drive circuits for driving the aforementioned galvano mirrors 17 and 18, respectively. Further, 32 and 33 are jump pulse generating circuits, respectively, and 34 is a first control circuit for controlling the sample hold circuits 26 and 27 and the jump pulse generating circuits 32 and 33.

Next, the operation of the third embodiment shown in FIG. 18 will be described. The luminous flux emitted from the light emission source 11 is focused and irradiated onto the information track 7 of the information recording medium 6 via the collimator lens 13, the beam splitter 15, the galvano mirror 17, the beam combining mirror 19 and the objective lens 5.
A focused spot 8 for reading out data is formed. The reflected light beam from the focused spot 8 passes through the objective lens 5, the beam combining mirror 19 and the galvano mirror 17 again, reaches the beam splitter 15, is reflected there, and is then split into two via the focusing lens 20. It will return to the photodetector 22. Here, since the known push-pull method is used as the tracking error signal detection method, the output from the two-division photodetector is input to the differential amplifier 24, and the differential amplifier 24 outputs the tracking error signal. There is.
This tracking error signal is supplied to the drive circuit 30 in the normal tracking control, and is used to drive the galvanometer mirror 17 to keep the focused spot 8 at the center of the information track 7.

Similarly, the luminous flux emitted from the light emitting source 12 is collimator lens 14, beam splitter 16,
The information track 7 of the information recording medium 6 is condensed and irradiated through the galvano mirror 18, the beam combining mirror 19 and the objective lens 5, and a condensed spot 9 is formed. The focused spot 9 is formed on the information track next to the information track on which the focused spot 8 exists. The reflected light flux from the focused spot 9 is again the objective lens 5 and the beam combining mirror 1.
9. Go through the galvanometer mirror 18 and the beam splitter 1
After reaching 6 and being reflected here, it is returned to the two-split photodetector 23 via the focusing lens 21. Here, since the known push-pull method is used as the tracking error signal detection method, the output from the two-division photodetector is input to the differential amplifier 25, and the differential amplifier 25 outputs the tracking error signal. There is. This tracking error signal is supplied to the drive circuit 31 in the normal tracking control, and is used to drive the galvanometer mirror 18 and keep the focused spot 9 at the center of the information track 7.

Next, a track jumping operation for reading continuous data without omission in the third embodiment will be described with reference to FIG.
Starting from FIG. 24, description will be made. First, FIG. 19, FIG.
An operation for track jumping only the focused spot 8 of the two focused spots will be described with reference to FIG.

FIG. 19 shows a state immediately before the focused spot 8 performs the track jumping operation. The focused spot 8 is on the nth information track, and the focused spot 9 is on the (n + 1) th information track, and the normal tracking control is performed for each focused spot. At this time, the sample hold circuit 26,
27 does not operate, and the outputs of the differential amplifiers 24 and 25 are directly output from the sample hold circuits 26 and 27. Also, the jump pulse generating circuits 32 and 33 are not operating.

FIG. 20 shows a state in which the focused spot 8 is performing the track jumping operation. During the track jumping operation of the focused spot 8, the sample hold circuit 26 operates to hold the tracking error signal of the focused spot 8 immediately before the track jumping operation. Furthermore, the focused spot 8 is moved from the nth information track to (n
The jump pulse generating circuit 32 for moving to the (+2) th information track is added to the drive circuit 30 through the adder 28 and the galvanometer mirror 17 is moved to the T in FIG.
Drive in one direction. On the other hand, the normal tracking control is performed on the focused spot 9, and the focused spot 9 becomes (n
It is held on the +1) th information track.

FIG. 21 shows a state immediately after the focused spot 8 has finished the track jumping operation. The focused spot 8 moves to the (n + 2) th information track, and the focused spot 9 remains on the (n + 1) th information track. The normal tracking control is performed on each focused spot. At this time, the sample and hold circuits 26 and 27 do not operate, and the differential amplifier 2
The outputs of 4 and 25 are directly output from the sample hold circuits 26 and 27. Also, the jump pulse generating circuits 32 and 33 are not operating.

Next, referring to FIGS. 22, 23 and 24,
An operation for performing track jumping on only the focused spot 9 of the two focused spots will be described.

FIG. 22 shows a state immediately before the focused spot 9 performs the track jumping operation. The focused spot 8 is on the (n + 2) th information track, and the focused spot 9 is on the (n + 2) th information track, and the normal tracking control is performed for each focused spot. is there. Similar to FIG. 19, the sample and hold circuits 26 and 27 do not operate, and the outputs of the differential amplifiers 24 and 25 are directly output from the sample and hold circuits 26 and 27. Also, the jump pulse generating circuits 32, 3
3 is not working either.

FIG. 23 shows a state in which the focused spot 9 is performing the track jumping operation. During the track jumping operation of the focused spot 9, the sample hold circuit 27 operates to hold the tracking error signal of the focused spot 9 immediately before the track jumping operation. Furthermore, in order to move the focused spot 9 from the (n + 2) th information track to the (n + 4) th information track,
The jump pulse is applied from the jump pulse generating circuit 33 through the adder 29 to the drive circuit 31 to drive the galvano mirror 18 in the T2 direction in FIG. on the other hand,
Normal tracking control is performed on the focused spot 8, and the focused spot 8 is held on the (n + 3) th information track.

FIG. 24 shows a state immediately after the focused spot 9 has completed the track jumping operation. The focused spot 9 moves to the (n + 4) th information track, and the focused spot 8 remains on the (n + 3) th information track. The normal tracking control is performed on each focused spot. At this time, the sample and hold circuits 26 and 27 do not operate, and the differential amplifier 2
The outputs of 4 and 25 are directly output from the sample hold circuits 26 and 27. Also, the jump pulse generating circuits 32 and 33 are not operating.

As described above, since the optical head shown in the third embodiment can perform track jumping on any one of the two focused spots, the track jumping method shown in the first embodiment is realized. it can. That is, each time the information recording medium makes one rotation, the focused spots 8,
Any one of 9 is jumped for two tracks alternately. Therefore, even when the information is read from the information recording medium having the single spiral information track by using the two focused spots, there is an advantage that the read information is not lost due to the track jumping.

In the third embodiment, the case of reading information by using the reflected light flux from the information recording medium has been described. However, the case of reading information by using the transmitted light flux from the information recording medium is described. Needless to say, it can be easily applied.

Example 4. FIG. 25 shows a case where data is read according to the track jumping method of the first embodiment from the information recording medium in which data is continuously recorded on a single spiral information track by using the device shown in the third embodiment. A circuit for synthesizing two data series read by the light spots 8 and 9 into one and making the reading speed about twice as fast as that of one focused spot is shown.
This is a two-division photodetector 2 in the configuration diagram shown in FIG.
2 and 23 are connected. In FIG. 25, 3
2, 33 are adders, 34, 35 are waveform equalization / shaping / discriminators, 36, 37 are demodulators, 38 is data synthesizing means, 43
Is a decoder / error corrector. Also, the data synthesizing means 38
39 and 40 are buffer memories, 41 is a second control circuit, and 42 is a switching circuit.

Next, the operation of the fourth embodiment will be described. First,
The two outputs of the two-split photodetector 22 are added by the adder 32, and the analog signal output from the adder 32 is converted into a digital signal by the waveform equalizer / shaperer / discriminator 34. Since the digital signal at this stage has undergone modulation such as EFM or (1-7) modulation, the next demodulator 3
Demodulated by 6. The two outputs of the two-divided photodetector 23 also pass through the adder 33, and the waveform equalizer / shaper / discriminator 35,
The demodulator 37 similarly processes.

By the way, the respective focused spots 8 and 9
Since the track jumping is performed once every time the information recording medium 7 makes two or more rounds, the data series output from the demodulators 36 and 37 are not continuous. Therefore, the buffer memory 3
The data sequences output from the demodulators 36 and 37 are temporarily stored in 9 and 40, and the data is input from one of the buffer memories selected based on the control signal from the control circuit 41 at an input speed of 2
Take out in double. The outputs from the buffer memories 39 and 40 are passed through the switching circuit 42 to the decoding / error correction unit 4
3, the decoder / error corrector 43 performs error correction and deinterleaving, and returns to the original continuous data sequence.

In order to describe the operation of the fourth embodiment in more detail, first, the data series read by the two converging spots will be described with reference to FIG. Here, a case is considered where data is continuously read starting from the (n + 1) th information track to the mth (m ≧ n + 2) information track, and in FIG. 26, the focused spot 8 (S1). The data series read by
The data series read by the focused spot 9 (S2) is shown in the lower row. In FIG. 26, n, n + 1 ,. ． ． n
+8 represents the number of the information track, and the length of the information track to which one number is given corresponds exactly to one round of the information recording medium. In addition, here, it is assumed that the information track assigned with one number is composed of eight sectors. By the way, since data in a sector is usually subjected to error correction and interleaving, it is necessary to continuously scan one sector with one focused spot for decoding.

26, T1, T2. Is the time when the focused spot starts track jumping. The focused spot 8 performs track jumping forward for two information tracks at time Tj (j = 1, 3, 5, ...), and the focused spot 9 moves at time Tk (k = 2, 4, 6, ...・
・ Use 2) to jump forward two information tracks.

The portions indicated by E1, E2, E3, and E4 are the time when the track jumping and the resynchronization after the track jumping are performed, and the time when the reading of data is interrupted. Here, it is assumed that the time for which the reading of data is interrupted by the track jumping is shorter than the time for scanning all one sector. Therefore, the time interval of track jumping, that is, T (i
In +1) -Ti (i = 1, 2, 3, ...), the subsequent focused spot scans the sector where the focused spot cannot be completely scanned during the time when the information recording medium makes one revolution. It's just a small addition to the time needed. For example, at time T1, the focused spot 8 is track-jumped from the nth information track to the (n + 2) th information track, and the state becomes ready for reading from the middle of sector 2 of the (n + 2) th information track. There is.

However, since the sector 2 is not completely scanned by the converging spot 8, the data of the sector 2 cannot be decoded by the condensing spot 8. Therefore, the subsequent focused spot 9 scans all the sectors 2 of the (n + 2) th information track. Therefore,
The time interval for track jumping is set to the time required for one rotation of the information recording medium (the time required for scanning eight sectors) plus the time required for scanning one sector, so that either one of The focused spot enables continuous scanning of any sector.

Further, as shown in FIG. 26, the data read by one focused spot lacks continuity due to track jumping. In the range shown in FIG. 26, the focused spots 8 are continuously read out from the sector 3 of the (n + 2) th information track to the sector 3 of the (n + 4) th information track, and ( sector 5 of the (n + 6) th information track
To sector 5 of the (n + 8) th information track. The focused spot 9 is read continuously from sector 1 of the (n + 1) th information track to sector 2 of the (n + 2) th information track and from sector 4 of the (n + 4) th information track. (N
Up to sector 4 of the +6) th information track.

As described above, the focused spots 8 and 9
Can scan all the sectors within the scanning range, but since the order of the sectors scanned by the focused spots 8 and 9 lacks continuity, the data sequence read by each focused spot also lacks continuity. It will be.
Therefore, in the following, the operation of the data synthesizing unit 38 to combine the data series read out by the respective focused spots into one continuous data series will be described in detail.

First, the input to the buffer memory 40 is started from time t0 shown in FIG. At time t0, the focused spot 8 is at the beginning of the sector 1 of the nth information track, and the focused spot 9 is at the beginning of the sector 1 of the (n + 1) th information track, and the focused spot 9 is read. The data is stored in the buffer memory 40. At time t1 shown in FIG. 26, the focused spot 8 moves to the end of the sector 5 of the (n + 2) th information track, and the focused spot 9 moves to the end of the sector 5 of the (n + 1) th information track. .

FIG. 27 shows the state of the data synthesizing means at the time t1, and the data n + 2: 3 to n + 2: 5 obtained from the focused spot 8 are stored in the buffer memory 39 starting from n + 2: 3, The data n + 1: 1 to n + obtained from the focused spot 9 is stored in the buffer memory 40.
Up to 1: 5 are stored with n + 1: 5 at the head. Here, for example, n + 2: 3 means the data of the sector 3 of the (n + 2) th information track. Output from the buffer memory is not performed until time t1, but this time t1
When it exceeds the limit, the switching circuit 42 causes the buffer memory 40 to
Connected to the side, the buffer memory 40 starts outputting.

Next, at time t2 shown in FIG. 26, the focused spot 8 is the sector 2 of the (n + 3) th information track.
At the end of, the focused spot 9 moves to the end of sector 2 of the (n + 2) th information track. FIG. 28 shows time t2
The data obtained from the focused spot 8 is sequentially input to the buffer memory 39, and eight sectors from n + 2: 3 to n + 3: 2 are stored starting from n + 2: 3. ing. Buffer memory 4
In addition to the five consecutive sectors stored at 0, time t
Data from n + 1: 6 to n + 2: 2 from 1 to time t2
5 consecutive sectors are newly input. However, since the buffer memory 40 can output at twice the input speed from the time t1, the input n + 1: 1 to n + 2:
All 10 consecutive sectors up to 2 will be output by time t2. On the right side of FIG. 28, a data series output from the data synthesizing means 38 by the time t2 is shown. Then, when the time t2 is exceeded, the switching circuit 4
2 is connected to the buffer memory 39 side, and the buffer memory 39 starts output.

Further, at time t3 shown in FIG. 26, the focused spot 8 is at the end of the sector 3 of the (n + 4) th information track, and the focused spot 9 is at the end of the sector 3 of the (n + 5) th information track. Move to. FIG. 29 shows time t
3 is the state of the data synthesizing means 38, and contrary to FIG. 28, all the data accumulated in the buffer memory 39 has been swept out. In addition to 8 consecutive sectors, 9 consecutive sectors of data n + 3: 3 to n + 4: 3 are newly input to the buffer memory 39 from time t2 to time t3. Like the buffer memory 40, the buffer memory 39 can output at twice the input speed, so that n + 2: 3 to n + 4: 3 input to the buffer memory 39.
All 17 consecutive sectors up to are output by time t3. On the right side of FIG. 29, the data series output from this data synthesizing means up to time t3 is shown.

On the other hand, the buffer memory 40 stores eight sectors from n + 4: 4 to n + 5: 3 by the time t3. Then, when the time t3 is exceeded, the switching circuit 42 is connected to the buffer memory 40 side, and the buffer memory 40 starts output.

Finally, at time t4 shown in FIG. 26, the focused spot 8 is at the end of the sector 4 of the (n + 7) th information track, and the focused spot 9 is at the sector 4 of the (n + 6) th information track. Move to the end. FIG. 30 shows time t
In the state of the data synthesizing means in No. 4, as in FIG. 28, contrary to FIG. 29, all the data accumulated in the buffer memory 40 has been swept out. In addition to the eight consecutive sectors, the buffer memory 40 has a time t3 to a time t.
Up to 4, nine consecutive sectors of data n + 5: 4 to n + 6: 4 have been newly input. Since the buffer memory 40 can output data at twice the input speed as described above, all 17 continuous sectors input to the buffer memory 40 will be output by time t3.

On the other hand, eight consecutive sectors from n + 6: 5 to n + 7: 4 are accumulated in the buffer memory 39 by time t4. Then, when the time t4 is exceeded, the switching circuit 42 is connected to the buffer memory 39 side. After that, the same procedure as described with reference to FIGS. 29 and 30 is repeated until the scanning of the m-th information track is completed, and the data from the (n + 1) -th information track to the m-th information track is continuously written. It is output.

In the third and fourth embodiments, the system having two converging spots has been described. Of course, the light source, the beam splitter, the galvano mirror, the beam combining mirror, the focusing lens, the adder, the sample hold circuit,
If another set of jump pulse generation circuit, drive circuit, waveform equalizer / shaper / discriminator, demodulator, buffer memory, etc. is prepared, a system with three or more focused spots can be easily realized. Data can be read from the information recording medium at a speed of about 3 times or more as compared with the case of the light spot.

Although a plurality of light emitting sources are used in the third embodiment, it goes without saying that a plurality of focused spots can be generated by using a multi-beam semiconductor laser or a combination of one light source and a diffraction grating instead. .

[0093]

Since the present invention is constructed as described above, it has the following effects.

In the track jumping method of the multi-beam optical head according to the present invention, only reading from one information track is continued at the time of track jump, and the rest is read from an unscanned information track different from the previous information track. Since the track jump is performed so that the data is read out in parallel, it is possible to scan all the portions of the single spiral information track in spite of reading the data in parallel, and it is possible to eliminate the loss of the read data.

Further, the most preceding focused spot is not subjected to track jumping, and the remaining focused spots other than this are jumped to an unscanned information track different from the information track before the track jump. It is possible to scan all parts of a single spiral information track despite the parallel reading of data, thus eliminating missing read data.

Further, the most preceding focused spot is not jumped to the track, and the remaining focused spots other than this are jumped to the information track at a position symmetrical to the focused spot not to be track jumped.
Despite the multi-beam optical head reading data in parallel, it is possible to scan all parts of a single spiral information track, eliminating missing read data and track jumping procedure. Makes track jumping easier to control.

Further, in the multi-beam optical head to which the track jumping method of the present invention is applied, track deviation correcting means is provided corresponding to each converging spot, and the track deviation correcting means outputs the tracking error signal generating means or Since either of the outputs of the jump pulse generation circuit is added, during track jumping, the most preceding focused spot is not subjected to track jumping, and the remaining focused spots other than this are not recorded before the track jump. Since it is possible to jump to an unscanned information track different from the track, it is possible to scan all parts of a single spiral information track in spite of reading the data in parallel, You can eliminate omissions.

Since the data synthesizing means for synthesizing the data read in parallel into a series of continuous data is provided, the reading speed of the data continuously recorded on the single spiral information track can be easily improved. can do. in this case,
There is no need to increase the number of revolutions of the information recording medium even if the data reading speed is increased, so there is no need to improve the performance of the focus servo or tracking servo, and the focus servo circuit, tracking servo circuit, optical head The focusing and tracking actuators can be inexpensively constructed. Furthermore, even if the number of focused spots is increased to increase the reading speed of data, the reading speed of data by one focused spot does not change, so a photodetector, waveform equalization / shaping / discriminator,
The frequencies handled by the demodulator and the like do not increase, and these can be constructed at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a position of a focused spot at time T1 and a trajectory of the focused spot until time T1 in a track jumping method using two focused spots according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a position of a focused spot at time (T1 + Δj) and a trajectory of the focused spot up to time (T1 + Δj) in Example 1;

FIG. 3 is the position of the focused spot at time (T1 + Δj + Δa) and time (T1 + Δj + Δa) in the first embodiment.
It is a figure which shows the locus | trajectory of the condensing spot to.

FIG. 4 is a diagram showing the position of the focused spot at time (T1 + Tr) and the trajectory of the focused spot up to time (T1 + Tr) in Example 1;

FIG. 5 is a diagram showing the position of the focused spot at time T2 and the trajectory of the focused spot until time T2 in the first embodiment.

FIG. 6 is a diagram showing the position of the focused spot at time (T2 + Δj) and the trajectory of the focused spot up to time (T2 + Δj) in Example 1;

FIG. 7 is the position of the focused spot at time (T2 + Δj + Δb) and time (T2 + Δj + Δb) in the first embodiment.
It is a figure which shows the locus | trajectory of the condensing spot to.

FIG. 8 is a diagram showing the position of the focused spot at time T3 and the trajectory of the focused spot until time T3 in the first embodiment.

FIG. 9 is a flowchart showing a procedure of a track jumping method using two focused spots according to the first embodiment.

FIG. 10 is a diagram showing the position of the focused spot at time T1 and the trajectory of the focused spot until time T1 in the track jumping method using three focused spots according to the second embodiment of the present invention.

FIG. 11 is a diagram showing the position of the focused spot at time (T1 + Δj) and the trajectory of the focused spot up to time (T1 + Δj) in Example 2;

FIG. 12 is the position of the focused spot at time (T1 + Δj + Δa) and time (T1 + Δj + Δ) in the second embodiment.
It is a figure which shows the locus | trajectory of the condensing spot to a).

FIG. 13 is a diagram showing the position of the focused spot at time (T1 + Tr) and the trajectory of the focused spot up to time (T1 + Tr) in Example 2;

FIG. 14 is a diagram showing the position of the focused spot at time T2 and the trajectory of the focused spot until time T2 in the second embodiment.

FIG. 15 is a diagram showing the position of the focused spot at time (T2 + Δj) and the trajectory of the focused spot up to time (T2 + Δj) in Example 2;

FIG. 16 is the position of the focused spot at time (T2 + Δj + Δb) and time (T2 + Δj + Δ) in the second embodiment.
It is a figure which shows the locus | trajectory of the condensing spot to b).

FIG. 17 is a diagram showing the position of the focused spot at time T3 and the trajectory of the focused spot until time T3 in Example 2;

FIG. 18 is a configuration diagram of an optical system that realizes a track jumping method using two focused spots according to a third embodiment of the present invention.

FIG. 19 is a diagram showing the position of a focused spot and the tracking servo state immediately before one focused spot of Example 3 is subjected to track jumping.

FIG. 20 is a diagram showing a position of a focused spot and a tracking servo state when one focused spot of Example 3 is performing track jumping.

FIG. 21 is a diagram showing a position of a focused spot and a tracking servo state immediately after one focused spot of Example 3 performs track jumping.

FIG. 22 is a diagram showing the position of a focused spot and the tracking servo state immediately before another focused spot of track jumping in the third embodiment.

FIG. 23 is a diagram showing a position of a focused spot and a tracking servo state when another focused spot of Example 3 is performing track jumping.

FIG. 24 is a diagram showing a position of a focused spot and a tracking servo state immediately after another focused spot of Example 3 is subjected to track jumping.

FIG. 25 is a configuration diagram of a circuit that synthesizes a data series from each of two focused spots into one continuous data series according to the fourth embodiment of the present invention.

FIG. 26 is a diagram showing a structure of a data series output from each of two focused spots according to the fourth embodiment.

FIG. 27 is a diagram showing a state of the data synthesizing means at time t1 in the fourth embodiment.

FIG. 28 is a diagram showing a state of the data synthesizing means at time t2 in the fourth embodiment.

FIG. 29 is a diagram showing a state of the data synthesizing means at time t3 in the fourth embodiment.

FIG. 30 is a diagram showing a state of the data synthesizing means at time t4 in the fourth embodiment.

FIG. 31 is a configuration diagram showing a main optical system of a conventional multi-beam optical head.

FIG. 32 is a schematic view showing an information recording medium having information tracks formed in a single spiral shape.

FIG. 33 is a diagram showing a position of a focused spot at time T1 and a trajectory of the focused spot until time T1 in a conventional track jumping method using two focused spots.

FIG. 34 is a diagram showing a position of a focused spot at time (T1 + Δj) and a trajectory of the focused spot up to time (T1 + Δj) in the conventional example.

FIG. 35 is a position of a focused spot at time (T1 + Δj + Δa) and time (T1 + Δj + Δa) in the conventional example.
It is a figure which shows the locus | trajectory of the condensing spot to.

FIG. 36 is a diagram showing a state of a focused spot and a locus on an information track at time (T1 + Tr) in a conventional example.

FIG. 37 is a diagram showing the position of the focused spot at time T2 and the trajectory of the focused spot until time T2 in the conventional example.

FIG. 38 is a diagram showing the position of the focused spot at time (T2 + Δj) and the trajectory of the focused spot up to time (T2 + Δj) in the conventional example.

FIG. 39 is the position of the focused spot at time (T2 + Δj + Δb) and time (T2 + Δj + Δb) in the conventional example.
It is a figure which shows the locus | trajectory of the condensing spot to.

FIG. 40 is a diagram showing the position of the focused spot at time T3 and the trajectory of the focused spot until time T3 in the conventional example.

[Explanation of symbols]

 3 Focused Spot 5 Focusing Means 6 Information Recording Medium 7 Information Track 8 Focused Spot 9 Focused Spot 17 Track Deviation Corrector 18 Track Deviation Corrector 22 2 Split Photo Detector 23 2 Split Photo Detector 24 Differential Amplifier 25 Difference Dynamic amplifier 32 Jump pulse generating circuit 33 Jump pulse generating circuit 38 Data synthesizing means

Claims (5)

[Claims] 1. In a track jumping method of an information reproducing apparatus for reading information in parallel from information tracks formed in a single spiral shape on an information recording medium, reading of data from the most preceding information track is performed. A track jumping method characterized by performing a track jump so as to read data from an unscanned information track that is different from the previous information track while continuing the rest. 2. A plurality of converging spots are irradiated onto an information recording medium in which information tracks are formed in a single spiral shape through one converging means, and the plurality of converging spots are adjacent to each other. In the track jumping method of the multi-beam optical head which is arranged on the upper side and uses the reflected light flux or the transmitted light flux from this information recording medium, the most preceding focused spot is not subjected to track jumping, and this is excluded. A track jumping method, wherein the remaining focused spot is jumped to an unscanned information track different from the information track before the track jump. 3. The track jumping method according to claim 2, wherein the condensed spot for track jumping is jumped to an information track at a position symmetrical with respect to the condensed spot not for track jumping. 4. A plurality of converging spots are irradiated onto an information recording medium in which information tracks are formed in a single spiral shape through one converging means, and the plurality of converging spots are adjacent to each other. In a multi-beam optical head which is arranged above and which reads information by using a reflected light beam or a transmitted light beam from this information recording medium, track deviation correction means for correcting track deviations of respective focused spots and respective track deviation correction means. The tracking error signal generating means for the focused spot and the jump pulse generating circuit are provided, and when the track jump is performed, the output of the tracking error signal generating means is added to the track deviation correcting means for the most preceding focused spot. The jump pulse generation circuit A multi-beam optical head characterized by applying the output of 5. A plurality of converging spots are irradiated onto an information recording medium in which information tracks are formed in a single spiral shape through one converging means, and the plurality of converging spots are adjacent to each other. In the multi-beam optical head which is arranged at the upper position and which reads the data continuously recorded on the information track by using the reflected light flux or the transmitted light flux from this information recording medium, when performing the track jump, The most preceding focused spot is not track-jumped, the remaining focused spots other than this are jumped to an unscanned information track different from the information track before the track jump, and read by each of the multiple focused spots. The data synthesizing means for synthesizing the data to be generated into a series of continuous data is provided. Chi-beam optical head.