JPH02141934A - Track retrieving device - Google Patents

Abstract

PURPOSE:To attain high speed track retrieval by adding an adder correcting an optical head transfer track number in an MCAV optical disk having a dummy track. CONSTITUTION:A difference between a retrieval object track address and a present track address is obtained and fed to an adder 10 as a transfer track signal 101. On the other hand, total number of dummy tracks included between the present position and the retrieval position is calculated and the number is applied to the adder 10 as a dummy track number signal 106. The adder 10 adds them and stores the result in a register 9. When an optical head 2 crosses a track, a cross pulse takes place as the tracking error signal 102, processed by a cross pulse detection circuit 6 and fed to a counter 8 as a cross pulse signal 103. The counter 8 subtracts the value from the setting value of the register 9 and when the result is zero, a linear motor stop signal 104 is outputted to stop a linear motor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a track search device for optical disk memories and the like.

BACKGROUND OF THE INVENTION In recent years, optical disk memory technology has attracted attention as a technology that enables significantly higher recording density and capacity than conventional magnetic recording, and is being researched in various places.

Conventional optical disc track search devices include, for example, Japanese Patent Application No. 130942/1982 and Japanese Patent Application No. 13816/1983.
It is stated in No. 5.

FIG. 3 shows a conventional example of this conventional track search device, in which numeral 1 denotes an optical disc for recording and reproducing information on tracks. Reference numeral 2 denotes an optical head that focuses a laser beam on a track of the optical disk 1 and records a signal on a recording film.

3 is an information reproduction signal or a focus error signal for focus control, which is obtained by amplifying the reproduction signal of the optical herad 2.

Tracking error signal 102 for tracking control
It is a head amplifier that generates such things. Reference numeral 4 denotes a linear motor for transporting the optical head 3 and head amplifier 4 to a predetermined track. Reference numeral 5 denotes an address reproducing circuit that reproduces an address signal from the sector identifier section of the sector of the optical disc 1. Reference numeral 6 denotes a traverse track detection circuit that detects the number of tracks traversed by the optical head 2 from the tracking error signal 102 of the head amplifier 3. 7 is a linear motor drive circuit for driving the linear motor 4. 8 is a subtraction counter that counts the traverse pulse signal 103 of the traversal track detection circuit 6 and outputs a linear motor stop signal 104 when the number of traversed tracks reaches a target value. Reference numeral 9 is a register for setting a transport track number signal 101 for transporting the optical helmet 2 to a target track.

In the conventional track search device configured as described above, first, the track position where the optical head 2 is currently located is known from the address signal 100 of the address reproducing circuit, and then the optical head 2 is detected.
The difference in the number of tracks from the target track to be newly transferred is set in the register 9 as the transfer track number signal 101. When the linear motor start signal 105 is applied to the linear motor drive circuit 7, the linear motor 4 causes the light
is transferred. When the optical head 2 crosses a track, a crossing pulse appears in the tracking error signal 102, and after being processed by the crossing track detection circuit 6, the crossing pulse signal 10
3 and counter 8, and counter 8 hits register 9.
is counted down from the set value. When the counter 8 reaches zero, a linear motor stop signal 104 is output to the linear motor drive circuit 7 to stop the linear motor 4.Next, the current track address is read from the address reproducing circuit 5, and if it is not the target track. The tracking actuator of the optical head 2 accesses the target track by a track jumping operation.

Problems to be Solved by the Invention However, in the above configuration, the so-called MCA
V (Modified Con5tant Ang
Track search for an optical disc that is formatted with ular velocity), has tracks with the same number of sectors, and has a dummy track that does not record or play back signals between bands to avoid the effects of crosstalk between adjacent bands. In this case, the cross-track detection circuit 6 also detects the dummy track as a cross-track, which causes a counting error in the counter 8. As a result, the head actuator repeats the track jumping operation many times, reducing the search speed. had.

MCAV optical disks are divided into a plurality of bands in the radial direction, and each band is structured into sectors such that the number of sectors in the track increases from the inner circumference to the outer circumference of the disk, and the recording density is adjusted between the inner and outer circumferences of the optical disk. By making it almost the same, the recording capacity can be increased to CAV (Constan
t Angular Velocity) of approximately 1, 5
It doubles. Therefore, since the number of sector divisions is different in at least one sector in tracks of adjacent bands, the sector identifier section in which the sector address is recorded is located in the data feed section, which is the area where data of the sector of the adjacent track is recorded. Therefore, if the crosstalk is large, there is a possibility that the sector identifier part of the adjacent track will be read and data will be recorded in the sector of the wrong track.

To avoid this mistake, dummy tracks are provided between bands.

In view of the above, an object of the present invention is to provide a trunk search device that can perform a high-speed track search by correcting cross-track counting errors.

Means for Solving the Problems The present invention provides an optical head for irradiating a light beam onto an optical disk, a light beam servo means for converging and following the light beam on a track, and a head transport means for transporting the optical head to a predetermined track position. , a crossing track number counting means for counting the number of tracks crossed by the light beam, a target crossing track number setting means for setting the search target track position by correcting the number of dummy tracks in the search area, and a counting means for the crossing track number counting means. The apparatus is equipped with a coincidence detection means for detecting coincidence between the result and the target number of tracks to be traversed.

Effect of the present invention With the above-described configuration, the target number of crossing tracks setting means sets a value obtained by correcting the number of dummy tracks included in the search area as the target number of crossing tracks.
It is detected that the count result of the crossing track number counting means of the failure detection means matches the target number of crossing tracks, and as a result, the head transporting means stops transporting the optical head.

Embodiment FIG. 1 is a block diagram of a track search device according to an embodiment of the present invention. In FIG. 1, the same numbers 1 to 9 and 100 to 105 as in FIG. 3 represent the same components or signals as in FIG. 3, and 10 is included in the search area for the transportation track number signal 101. An adder for adding and correcting a dummy track number signal 106 indicating the total sum of dummy tracks; This is a dummy track number signal to set.

FIG. 2 is an external view of an optical disc used in the trunk search device of FIG. 1. The optical disc 1 has a track area 11 divided into bands 12 in the radial direction. As a specific example, band 120) and band 12 (+-1) are shown. Band (i) is sector S1. S2. −・・・
, Sn, Sn+1, the band (i-
1) is divided into n sectors S1, S2°, . . . , 5n-1, Sn.

Each sector has a sector identifier section ID at the beginning in which an address is recorded, and the area following the ID is a data field section in which data is recorded. Between the bands is a dummy track 1
3 is placed.

As is clear from FIG. 2, the ID of the track located at the band boundary indicates that crosstalk occurs in the data field portion of each track at the band boundary. Therefore, if the optical head now searches for the track at the boundary of band (+), the optical head will search for band 0 of band (++1).
), when the crosstalk ID signal of band 0) is read and the search is completed normally, if data is recorded in this state, the track of band (++1) adjacent to band 0) will be searched. The dummy track is an area in which no information is recorded or reproduced, so the above-mentioned erroneous recording is prevented.

Further, in order to maintain address continuity in tracks other than the dummy track, a special signal that can be distinguished from a normal track is recorded on the dummy track. For example, the same address as the band boundary track may be duplicated, and an identification flag may be recorded in an empty bit of the address, or a special signal may be recorded.

The operation of the track search device of this embodiment configured as described above will be described below.

When a track search request is made, first the address signal 100 is read from the address reproduction circuit 5 in order to know the track position where the optical head 2 is currently located. Next, the difference between the search target track address and the current track address is determined and applied to the adder 1O as the transfer track number signal 101. On the other hand, the total number of dummy tracks included between the current position and the search position is calculated from the track arrangement of each band of the MCAV format of the optical disc 1, which is known in advance, and is also applied to the adder 10 as a dummy track number signal 106. Then, it is added to the previous transfer track number signal 101 and stored in the register 9.

The linear motor start signal 105 is the linear motor drive circuit 7
, the linear motor 4 moves the optical head 2 in the radial direction of the optical disk 1 toward the target track. The light beam emitted from the optical head 2 traverses the guide track of the optical disc 1, generates a track crossing pulse in the tracking error signal 102, and sends the traversing pulse signal 103 shaped by the traversing track detection circuit 6 to the counter 8. Input the clock.

The counter 8 advances the count by subtracting from the set value of the register 8, and when the counter 8 reaches zero, it outputs a linear motor stop signal 104 to the linear motor drive circuit 7 to stop the movement of the linear motor 4.

Then, continuing the address signal 100, the light
It is checked whether or not the target track is present, and if it is different, the actuator of the optical head 2 performs a track jumping operation to perform a fine search to the target track.

As described above, according to this embodiment, an adder is provided for correcting the number of tracks to which the optical head is transferred, and the number of dummy tracks included in the search area is corrected to the number of tracks to which the optical head is transferred. It is possible to suppress errors and perform high-speed track searches.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, in an MCAV optical disk having dummy tracks, an adder for correcting the number of tracks to be moved by an optical head is provided, and the track search is performed by correcting the number of dummy tracks in the search area. It can be performed at high speed and has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a track search device according to an embodiment of the present invention, FIG. 2 is an external view of an optical disc to which the track search device of FIG. 1 is applied, and FIG. 3 is a block diagram of a conventional track search device. be. 1... Optical disk, 2... Optical head,
3...Head amplifier, 4...Linear motor, 5...Address regeneration circuit, 6...
- Crossing track detection circuit, 7... Linear motor drive circuit, 8... Counter, 9... Register, lO... Adder, 11... ...Track area! 2...Band, 13...
・Dummy truck. ■D... Sector identifier part, Sl, S2, 5n-
1゜Sn, Sn+l...Sector, 100...
... Reproduction signal, 101 ... Transport track number signal, 102 ... Tracking error signal, 103
- Old: Crossing pulse signal, 104: Linear motor stop signal, 105: Linear motor start signal, 106: Dummy track number signal. Name of agent: Patent attorney Tamaaki Awano (1 person) Figure 1

Claims (2)

[Claims] (1) A track search device that searches for a track on an optical disk that divides the disk into a plurality of bands in the radial direction, and the number of sectors in each band increases from the inner circumference to the outer circumference of the disk. an optical head that irradiates a light beam onto a track of the optical disk; a light beam servo means that causes the light beam to converge and follow the track; and a head transfer means that moves the optical head to a predetermined track position. Crossed track number counting means for counting the number of tracks crossed by the light beam;
a target crossing track number setting means for correcting and setting the number of tracks up to the search target track by the number of dummy tracks provided between the bands included in the search area; and counting results of the target crossing track number counting means and the target. A track search device comprising: a coincidence detecting means for detecting a coincidence with the number of tracks traversed; and the head moving means is stopped by an output of the coincidence detecting means. (2) The target number of tracks setting means sets a value obtained by adding the number of dummy tracks provided between bands to the number of traversed tracks up to the target track as the target number of traversed tracks. track search device.