JPH0652639A - Information recording medium and tracking error detection device - Google Patents

Abstract

PURPOSE:To reduce the time required for a tracking by alternatively placing wobble mark pairs which generate tracking error signals that have mutually reversed characteristics and making the total number of pairs per one track period an odd number. CONSTITUTION:Wobble mark pairs, which supply plus and minus tracking error signals, are alternatively and waveringly placed on a track, In front of the wobble mark pairs, which are odd number per one track period, an identifier is provided so as to discriminate polarities. When an identifier detection means 52 detects the identifier, the wobble pair, which are detected later, have a positive polarity and if not detected, the wobble mark pair has a negative polarity. Prior to the detection of wobble mark pairs, the output of the means 52 switches a sequential switch 56 to either a noninverted amplifier 54 or an inverted amplifier 55. Thus, tracking error detection signals with a same polarity are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc-shaped information recording medium capable of optical or magnetic high density recording, and a tracking error detecting device for obtaining a tracking error signal from the information recording medium.

[0002]

2. Description of the Related Art Conventionally, information recording media have been disclosed in US Pat.
As described in No. 562,564 (December 31, 1985), a wobble mark formed along a spiral track center line is used to detect a positional deviation error from the track center line. Has been done.

FIG. 5 is a block diagram of a conventional information recording medium, FIG.
Shows a configuration diagram of the main part thereof. In FIGS. 5 and 6, 11 and 12 are spiral track center lines 1.
It is a wobble mark formed along 0. 20, 2
1 and 200 are recorded information.

Next, the operation of the above conventional example will be described. In FIGS. 5 and 6, the wobble marks 11 and 12 are shown.
Are formed at a predetermined interval from each other, and are formed at positions shifted by 1/4 track pitch with respect to the track center line 10 in opposite directions (outer peripheral side and inner peripheral side). The wobble marks 11 and 12 are provided to detect a tracking error signal, that is, an amount of positional deviation error from the track center line of the recording / reproducing head. If the recording / reproducing head is displaced toward the outer circumference side or inner circumference side with respect to the track center line 10, the wobble mark 11
Alternatively, since 12 is detected larger than the other, tracking error can be detected by this.

Here, the track center line does not necessarily mean a linear formation that actually exists on the information recording medium, but rather the line segments equidistant from the wobble marks 11 and 12 are continuously connected. It is generally regarded as a virtual line. The record information 20 is recorded along the track center line.

As described above, even in the conventional information recording medium, the tracking error signal can be detected by forming the wobble marks 11 and 12 along the track center line 10.

[0007]

However, in the above structure, the following problems occur when the track recording density is increased.

First, when the track pitch is reduced to near the minimum resolution of the information reading head, the wobble mark 1
It is difficult to distinguish 1 or 12 from the wobble mark in the adjacent track. That is, each wobble mark is detected with the same amplitude regardless of the tracking error. As a result, the tracking error signal cannot be detected.

It is possible to double the track density of recorded information while maintaining the track density of wobble marks. That is, the information 200 may be recorded between the adjacent track center lines 10 as shown by the broken lines in FIG.
However, in this case, the track on which the information 20 is formed and the track on which the information 200 is formed cannot be continuously formed in a spiral shape. This is clearer than in FIG. For example, now, the recording / playback head has recording information 2
It is assumed that it is located above 0. When the track center line 10 is formed in a spiral shape and the disk-shaped information recording medium makes one rotation, the recording / reproducing head jumps over the recording information 200 recorded between the tracks and is positioned on the recording information 21. Will be done. In order to position the recording / reproducing head on the recording information 200, the polarity of the tracking error signal must be inverted once. This is extremely inconvenient when a large amount of continuous information such as a moving image is processed at high speed.

In view of the above problems, the present invention can record information with a track density twice as high as that of the conventional one, and moreover all tracks can be continuously formed. Further, the present invention provides an information recording medium which can be turned on and off instantly when the recording / reproducing head is moved to an arbitrary track, and a tracking error detection device which generates a tracking error signal from the information recording medium.

[0011]

In order to solve the above-mentioned problems, the information recording medium of the present invention comprises first and second wobble marks which generate tracking error signals having polarities opposite to each other alternately and in units of one track. Each wobble mark is arranged such that the total number of hits is an odd number, and an identifier indicating the polarity of the tracking error signal is arranged in front of each wobble mark.

[0012]

According to the present invention, since the first track identification mark and the second track identification mark are arranged in a zigzag manner by the above-mentioned structure, the track density can be increased while all the tracks are continuously spirally connected. Even if the number of times is doubled, each track identification mark is independently identified, and as a result, an information recording medium having a recording density twice as high as that of the conventional one can be realized. Further, by providing the identifier, the polarity of the tracking error signal can be instantly discriminated when the recording / reproducing head is moved to an arbitrary track.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An information recording medium according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a top view of an information recording medium according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of the main part thereof. In FIG. 1, 10 is a track center line provided in a spiral shape. This is a virtual one as described in the conventional example. The track pitch is half that of the conventional example, that is, the track density is doubled. 1
Reference numerals 1 and 13 are first track identification marks, and 12 and 14 are second track identification marks. Reference numerals 11 and 12 are first wobble marks formed along the track center line 10, and reference numerals 13 and 14 are second wobble marks formed along the same track center line. Since the track pitch of this embodiment is half that of the conventional example, the distance of the wobble mark from the track center line is 1/2 track pitch. The difference between the first wobble mark and the second wobble servo mark is that, as clearly shown in FIG. 1 and FIG.
The arrangement of 1, 12 and 13, 14 is reversed.

That is, the first wobble marks 11 and 12
The tracking error signal obtained from the second wobble marks 13 and 14 has the opposite polarity to the tracking error signal obtained from the above. Reference numeral 30 is an identifier, which is provided before the first wobble mark. Therefore, the identifier 30
Is detected, the wobble mark located behind it is the first wobble mark, and if it is not detected, it is the second wobble mark.

The first wobble marks 11, 1 are also used.
The second and second wobble marks 13 and 14 are alternately formed, and further, the first and second wobble marks are formed.
It is assumed that the total number of wobble marks is an odd number per track period (track for one round).

The operation of the information recording medium having the above structure will be described below with reference to FIGS. 1, 2 and 3.

FIG. 3 shows the functions of the first and second wobble marks which have polarities opposite to each other and which are alternately arranged. In FIG. 3, black circles represent wobble mark pairs that generate a tracking error signal of one polarity (for example, positive polarity), and an identifier 30 is provided in front of them. Now, it is assumed that the head moves on the track 10a in the direction of the arrow and is at the position A. At this time, the head is the identifier 30
Wobble mark pair 11, 1 to detect the reproduction signal of
It can be recognized that 2 is the first wobble mark having the tracking error signal of positive polarity. Next, the head scans over the wobble mark pair 13 and 14, but it does not detect the reproduced signal of the identifier, so that it is possible to recognize that these are wobble marks that provide tracking errors of opposite polarities (negative polarity). it can. In this way, the polarity of the wobble mark can be determined by determining whether or not the identifier 30 is present before the wobble mark pair.
The positive and negative tracking error signals can be on-tracked to a predetermined track without canceling each other out.

Further, if the head scans one track period, the head comes on the adjacent track 10b.
As described above, since the total number of positive and negative wobble mark pairs per track period is an odd number, the position of the positive wobble mark pair in the adjacent track is the same as that of the negative wobble mark pair in the preceding track 10a. Come to position B next door. The wobble mark 14 that constitutes the negative wobble mark pair in the preceding track forms one corner of the positive wobble mark pair in the adjacent track. The same applies to the adjacent tracks, and eventually all the tracks are continuously formed in a spiral shape. At this time, the positive wobble marks and the negative wobble marks are arranged in a zigzag pattern.

As described above, according to the present embodiment, the first wobble mark and the second wobble mark pair which generate the tracking error signals having mutually opposite characteristics are alternately arranged, and the total number per track period is an odd number. As a result, the track density is doubled as compared with the conventional one, and an information recording medium in which all tracks are continuously connected can be realized. Further, the first wobble mark and the second
By providing an identifier in front of the wobble mark pair of
The polarity of the tracking error signal can be instantly determined and the time required for tracking can be shortened.

In this embodiment, the identifier is placed before the wobble mark pair, but the identifier may be placed after the wobble mark.

Next, a tracking error detecting device for generating a tracking error signal from the information recording medium will be described with reference to the drawings.

FIG. 4 is a block diagram of a tracking error detecting device in one embodiment. In FIG. 4, reference numeral 50 denotes a first detecting means, which detects the amplitude of the first track identification mark when the head scans it. 51
Is a second detecting means for detecting the amplitude of the second track identification mark. Reference numeral 52 is an identifier detecting means for determining whether or not an identifier is provided before the wobble mark. Reference numeral 53 is a tracking error calculation means for generating a tracking error signal from the wobble mark pair. Reference numerals 54 and 55 are a non-inverting amplifier and an inverting amplifier, respectively. Reference numeral 56 denotes a switch, which selects one of the outputs of the non-inverting amplifier 54 and the inverting amplifier 55 by the output of the identifier detecting means 52,
Output as tracking error signal. The non-inverting amplifier 54, the inverting amplifier 55, and the switch 56 form the polarity inverting means 57.

The tracking error detecting device configured as described above will be described below. As described in the previous embodiment, wobble mark pairs for supplying positive and negative tracking error signals are alternately arranged in a staggered pattern on the track, and the polarities are placed in front of the wobble mark pairs. An identifier for distinguishing is provided. When the identifier detecting unit 52 detects this identifier, the wobble mark pair to be detected later has a positive polarity, and if not detected, the wobble mark pair has a negative polarity. That is, the output of the identifier detecting means 52 sequentially switches the switch 56 to the non-inverting amplifier 54 or the inverting amplifier 55 before the wobble mark pair is detected. As a result, the non-inverting amplifier 54 becomes valid for the positive wobble mark pair, and the inverting amplifier 55 becomes valid for the negative wobble mark pair, so that the tracking error detection output of the same polarity is eventually obtained. Will be obtained.

According to this embodiment, the identifier located before the wobble mark pair is detected, but an apparatus for detecting the identifier located after the wobble mark pair may be used. Further, the identifiers need not be attached to all wobble mark pairs, and may be provided at appropriate intervals.

As described above, according to this embodiment, it is possible to detect tracking error signals of the same polarity by detecting the identifier.

[0027]

As described above, according to the present invention, wobbling mark pairs that generate tracking error signals having mutually opposite characteristics are alternately arranged, and the total number per track period is an odd number. As a result, the track density is doubled, and an information recording medium in which all tracks are continuously connected can be realized. Further, by providing the identifier before or after the wobble mark pair, the polarity of the tracking error signal can be instantly discriminated, and the time required for tracking can be shortened. That is,
After the access, it is possible to determine the polarity of the wobble mark by waiting for, for example, the index signal, but during that time, it is necessary to wait for about half a turn, and the head goes to a place other than the target track. Therefore, it is essential to provide an identifier for high speed access.

Further, even if there is a missing servo mark due to a burst due to a scratch or the like, by providing an identifier,
Tracking can be restored easily and instantly.

[Brief description of drawings]

FIG. 1 is a top view of an information recording medium according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of an information recording medium according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of an information recording medium for explaining the operation in one embodiment of the present invention.

FIG. 4 is a block diagram of a tracking error detection device according to an embodiment of the present invention.

FIG. 5 is a front view of a conventional information recording medium.

FIG. 6 is a configuration diagram of main parts of a conventional information recording medium.

[Explanation of symbols]

 10 track center line 11, 13 first track identification mark 12, 14 second track identification mark 11, 12 first wobble mark 13, 14 second wobble mark 20, 21, 200 recording information 30 identifier 50 first Detecting means 51 second detecting means 52 identifier detecting means 53 tracking error calculating means 54 non-inverting amplifier 55 inverting amplifier 56 switch

Claims (5)

[Claims] 1. An information recording medium in which servo marks are arranged periodically and discretely, wherein the servo marks are 1
An information recording medium, characterized in that an odd number of servo marks are present per track unit, and the servo mark includes first and second track identification marks and an identifier indicating an arrangement state of the first and second track identification marks. 2. The information recording medium according to claim 1, wherein a pair of wobble marks is constituted by the first track identification mark and the second track identification mark of the adjacent track. 3. The information recording medium according to claim 1, wherein first and second wobble marks having mutually opposite detection characteristics are alternately arranged. 4. The information recording medium according to claim 1, 2 or 3, wherein one sector comprises a first and a second track identification mark, an identifier and recording information. 5. A tracking error detection device for detecting a tracking error from the information recording medium according to claim 1, wherein the first detection means detects an amplitude of a first track identification mark, and a second track identification. Second detecting means for detecting the amplitude of the mark, identifier detecting means for detecting the identifier, tracking error calculating means for obtaining a tracking error signal from the output signals of the first and second detecting means,
A tracking error detecting device comprising: a polarity inverting means for alternately switching the polarity of the output signal of the tracking error calculating means in accordance with the output signal of the identifier detecting means.