JPS6142785A - Track retrieval - Google Patents

Abstract

PURPOSE:To shorten the access time at the retrieval of a track by executing the jump scan of a track having no recorded data. CONSTITUTION:An optical head 2 is shifted by a feed motor 3 while crossing each track of an optical disk 1. With respect to a track having no record in its address area and data area a high frequency detection signal SIG with not be detected from an RF detection circuit 5. A jump signal STJ from a control CPU7 is supplied to a tracking servo circuit 6 and said track with no record is subjected to the jumping scan, whereby no address retrieval is carried out. By this jumping scan the track retrieval is quickly carried out, and the access time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for searching spiral or concentric tracks formed on an optical disk, etc., and more specifically, 1.
The present invention relates to a 1-rack search method in which data is recorded in units of tracks and position information (address) is also recorded when this data is recorded.

[Prior art]

Optical discs and the like are used as recording media for various information.

This is a disk-shaped medium (hereinafter referred to as a disk).
It has spiral or concentric tracks,
Each track is specified by the position information recorded on each track, that is, the track address, and is searched to write and read data.

By the way, when data recorded on the disk as described above is not to be read, the track in which the data to be read is recorded is searched, the reading device is positioned at that position, and then,
A signal recorded on a track is read out, and in this case, the reader is first moved by referring to the address of the target track and the track pinch. Now, at this time, for example, the accuracy of the movement control of the reading device should be set to 2.
If the I/rack pitch is approximately 0 microns and the I/rack pitch is 2 microns, the accuracy will be approximately 101-rack. However, in reality, the eccentricity of the disk is about 30 microns, and the eccentricity of the turntable that rotates the disk is about 60 microns, so the overall accuracy is about 50 tracks at maximum.
In reality, in order to search for a target track, it is necessary to sequentially check the addresses of these approximately 50 tracks, which takes a considerable amount of time.

Therefore, it is important to shorten the time required for such a track search (access time), and methods for this purpose have been proposed, for example, in Japanese Patent Publications No. 59-16347 and No. 59-16348.

In both of these inventions, the reading device is moved at high speed in the radial direction of the disk to within a certain range centered on the track to be searched, and after roughly positioning the device, the address of each track is sequentially read. According to Japanese Patent Publication No. 59-16347, the tracking control system is controlled by keeping the tracking servo off or by setting the DC loop gain to a small value and moving the reader at high speed until N tracks before the target track. It is said to stabilize operation and enable accurate and quick search for the desired track. Furthermore, in Japanese Patent Publication No. 59-16348, the reading device is moved at high speed until the difference between the address detected by the reading device and the target address becomes less than a predetermined setting value, and then the address of the track at that position is Read the address, move the reader by the number of tracks corresponding to the difference from the target address, read the address again, and repeat this process to position the reader on the target track. It is said that this can be done.

[Problem that the invention seeks to solve]

However, both of the above-mentioned inventions are intended for disks in which addresses are recorded in advance on all tracks. For this reason, there is a problem that this method cannot be applied to a disc in which an address is not recorded on each track before use, and an address is also recorded at the same time when data that should originally be recorded on a track is recorded. In other words, in a disc in which an address is also recorded when data is recorded on a track, neither the data to be recorded nor the address seems to be recorded in the tracks before and after the track from which the data is to be read. There are cases where Even in such a case, the conventional method described above reads the address of each track for which even a track address is not recorded until the track to be searched is detected.
The process of comparing this with the track address to be searched is repeated. For this reason, there is a problem that it is impossible to shorten the access time.

[Means for solving problems]

The present invention has been made in view of the above-mentioned circumstances, and it first detects whether or not any signal is recorded on the track in a disc configured such that when data is recorded on the track, an address is also recorded at the same time. However, it is an object of the present invention to provide a track search method that shortens access time by performing a skip operation for tracks on which no signals are recorded.

The present invention records track addresses for searching when recording data! Full! In a track search method for a recording medium having spiral or concentric tracks,
The present invention is characterized in that the presence or absence of recorded data on each track is detected, tracks with no recorded data are scanned in an interlaced manner, and tracks where recorded data is detected are searched for by reading their addresses.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments of an optical disc.

FIG. 2 is a schematic diagram showing the structure of an optical disc.

The optical disc I is a disc-shaped recording medium having a center hole IC75<i5+'l for being fixedly placed on a turntable (not shown), and a concentric track formed around the center hole IC75<i5+'l. An address area Δ in which the address information of each track is recorded is formed in a fan-shaped part having a predetermined angle, and the other parts are recorded on the disk.
L! Data area I where the statement M debt report etc. to be recorded is recorded
It is D. In the embodiment of the present invention, the data recorded in the data area LD has a fixed length.

FIG. 1 is a schematic diagram of an optical disc reader used to implement the method of the present invention.

The optical head 2 converts data recorded in each concentric track formed on the optical disc 1, that is, address information recorded in the address area LA of each track and a signal recorded in the data area ID, using a laser or the like. This is an optical reading device using a light source, and the read optical signal is converted into an electrical signal and amplified by an amplifier 8, and then
The signal is applied to an address reading circuit 4, an IIF (high frequency) detection circuit 5, and a tracking servo circuit 6.

When the address reading circuit 4 receives a signal related to the address recorded in the address area 1^ of each track, which is read by the optical head 2 and converted into an electric signal,
This is read and output to the control CPU 7. .

The RF detection circuit 5 detects when a high frequency is included in the signal read by the optical head 2, that is, when a signal is already recorded in either or both of the address area 18 and data area ID of each track. Detect this and control CPL
A predetermined signal SIG is output to I7.

The tracking servo circuit 6 detects the position of the optical gutter 2 with respect to each track based on the signal read by the optical head 2, and this detection result is fed back to the optical gutter 2 to determine the position of each track. When a recorded signal is read, the position of the optical gutter 2 is controlled so that it always follows the track to be read. Note that the position control of the optical head 2 by the tracking servo circuit 6 is about several tens to 1001 ranks, and movement beyond that is performed by the feed motor 3, which will be described later. Also control CP
When the tracking servo circuit 6 receives a track jump instruction from U7, the reading position of the optical head 2 is moved in the radial direction of the optical disc 1 in order to operate the next track.

The feed motor 3 moves the optical head 2 according to instructions from the control CPU 7.
This is for moving the optical disc l in the radial direction at high speed.

1 and the control CPU 7 inputs the 7 and 2 signals to the optical system according to the manual signals from the address reading circuit 4 and the IIF detection circuit 5 as described above.
The signal related to the address recorded in the address area IA of the track where the The tracking servo circuit 6 performs fine positioning of the track to be read and compensation for positional deviation.

The method of the present invention carried out by the disc reading device configured as described above will be described below with reference to the timing chart of FIG. 3 and the flowchart of FIG. 4.

Currently, each track number N-4, N-3 shown in 3rd floor (al)
, N-2゜N-1, N, N+1, etc., among the tracks whose address information is N, the track Tn with number N is set as the search target, and the search target is searched for, for example, about several tens of tracks on both sides of the track Tn to be searched. It is assumed that no signal is recorded in the address area IA as well as in the data area LD of each track.

Now, when a search for track Tn is instructed, control CPt
17 calculates the position of the track Tn from the address N of the track Tn and the track pinch (step 2), and according to this result, controls the feed motor 3; It is determined whether a signal is recorded on the track on which the optical head 2 is positioned, that is, whether a high frequency is detected by the RF detection circuit 5 (step 2). The optical head 2 is placed at the position of the track T r+-4.
is located, since no signal is recorded in either the address area IA or the data area II) of this track Tn-, the control CP is sent from the RF detection circuit 5.
The signal SIG is not given to U7 (step ■), so that the control CI'U7 outputs a track jump signal STJ to the tracking servo circuit 6 as shown in FIG. 3 (C1) to instruct track jump (step ■). .

By the tracking servo circuit 6 supplied with the track jump signal STJ, the optical groove 2 is sequentially moved in the radial direction of the optical disc (2) across the next tracks 'rn-,'rn-2, etc., and during this time Each track “r, -,,
T11-2... are scanned by the optical head 2. However, since no signal is recorded in either the data area ID or address area LA for 'track jump,' I? The F detection circuit 5 does not detect high frequencies, and therefore, as shown in FIG.

Since the control CPυ7 does not receive the signal SIG,
It is determined that no signal is recorded on the track Tn-3 that the optical head 2 is currently crossing, that is, it is not the track Tn to be searched, and the track jump signal STJ is given to the tracking servo circuit 6 as before. (Step ■).

As described above, while steps (2) and (2) are repeated and the optical head 2 is moved along the radial direction of the optical disc 1, the control CPU 7 determines whether or not the signal SIG is input from the RF detection circuit 5, If the signal SIG is not input, the track jump signal STJ is output to the tracking servo circuit 6, the optical disc 2 is moved in the radial direction of the optical disc 1, and the processes of steps ① and ② are repeated to sequentially operate the next track. do.

While this process is repeated, the signal S from the IIF detection circuit 5
When IG is input, in other words, the track in which the address-related signal is recorded, that is, the search target track Tr1
When the optical head 2 is positioned at the position, it is determined that some signal is recorded on that track, the output of the track jump signal STJ is stopped, and the process proceeds from step ■ to step ■, where the optical head on that track is moved. 2, and the control CI"'U7 reads the address input from the address reading circuit 4 (step ■),
This and the address N of the track Tn to be searched are compared (step (2)), and if they match, this track is determined to be the track Tn to be searched, and the search process is terminated.

Note that in addition to the search target track Tn, if some information is recorded on each of the three tracks, for example, tracks 'r, -3, 'rn-2, and 'rn-,' In step ■, it is detected that a signal is recorded on track 'rn+3, and in step ■, the address of this track 'rn-3 is read, but search statement 4
Since it does not match the address N of the elephant track Tn, proceed to step ① and select the "address of the search target track Tn" -
The current position of the optical head 2 and the track T to be searched are determined by calculating the "address of the track at the current position" (step 2). Since we can find the number of tracks between
Search by skipping between them (step ■).

That is, in the above example, "search target track T.

Since the result of ``address of current track'' - ``address of current track'' is ``3'', the optical radar 2 will be located at the position of the search target track Tn if three tracks are skipped, and the search will be performed again. The addresses are read and confirmed, and if they match, the process ends.

〔effect〕

As detailed above, the track search method according to the present invention includes:
Although the address information ffa is recorded in itself,
When searching for a track on which no address information has been recorded after +iii, instead of reading the address information of each track one by one and searching for the target track,
Since the target track is searched by checking whether any information is recorded on each track, a quick search is possible.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG. 1 is a schematic diagram of an optical disc to be read by the method of the present invention, and FIG. 2 is a block diagram of an optical disc reading device for carrying out the method of the present invention. Figure 3 is the timing chart, Figure 4
The figure is a flowchart showing the processing contents of the control CPU.

Claims (1)

[Claims] 1. In a track search method for a recording medium having spiral or concentric tracks for recording track addresses for search when recording data, the presence or absence of recorded data on each track is detected. , A track search method characterized in that a track with no recorded data is scanned in an interlaced manner, and a track where recorded data is detected is searched for by reading the address of the track to be searched.