JPH0278024A - Track access method in optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To contrive the high speed of track access by extracting only a track crossing signal based on the level difference of the reflection light quantity between a recording signal regenerated when an optical head crosses a recording track and the track crossing signal. CONSTITUTION:The read signal of an optical head 9 is inputted through an amplifier 10 to a track crossing signal (STC) extracting circuit 11. The read signal includes an STC component and a recording signal component, whereas, since the lowest value of the recording signal is higher than the lowest value of the STC, the circuit 11 extracts only the STC by comparing the signal with a reference voltage VR by means of a level comparator 16. Consequently, based on the STC extracted by the circuit 11, the position control of the head 9 is highly accurately executed, and even when the STC approaches the frequencies of the recording signal, the high-speed track access is attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for optically recording information by irradiating a converging surface of an optical recording medium such as an optical disk or a magneto-optical disk with focused light from a gas laser, a semiconductor laser, etc. The present invention relates to an optical recording/reproducing device that performs playback or recording, playback, and erasing, and particularly relates to an improvement of a track access method that does not cause access errors even when the track access speed is increased in this type of device.

[Prior Art] Conventionally, as an optical recording medium applied to this type of optical recording/reproducing device, a type having a recording layer on one side is taken as an example and illustrated in FIGS. 16 to 17. A transparent substrate (b) provided with a pre-groove (a) as shown in FIG. It is known that the main part thereof is composed of a protective layer (d) and a protective layer (d).

Then, inputting the recording information to this optical recording medium (e) is as follows:
As shown in FIG. 16, the condensed recording light (C1) from a light source such as a semiconductor laser, which is condensed by a condensing lens (not shown) mounted on the optical head (f), is directed to a predetermined portion of the recording layer (C). The recording layer (C) undergoes phase change, magnetization reversal, deformation, etc. in the irradiated area, and recording dots (h
).

On the other hand, when reproducing the recorded information, as shown in FIGS.
), and the reflected light is input to a light receiving element (j) such as a photodiode for reproduction.

By the way, when calling up a target track of the optical recording medium (e) and reproducing predetermined recorded information thereof, conventionally, the optical head (f) is moved across the pregroove (a) of the optical recording medium (e). track crossing signals that are generated when the optical head (f) crosses this pre-groove (a), and count the number of detected track crossing signals to determine the direction of the optical head (f). A method of controlling the position is adopted.

In this case, during track access,
As shown in Figure 1, the optical head (f> is the pregroove (a
) as well as the recording dot (h) portion, a recording signal is generated not only in the pregroove (a) but also in the recording dot (h) portion.

However, since the optical recording medium (e) is rotating and the optical head (f) reads a large number of recording dots (h) while crossing the recording dot (h) portion, the optical recording medium (e) is rotating.
The recording signal generated in part h) is a high frequency signal having a frequency component of about 1 to 5 MHz, whereas the track crossing signal during track access is generated when crossing the pull group (a) and has a frequency of 100 MHz.
It has a low frequency component of about ~300KH2 or less.

Therefore, by frequency-separating the output of the optical head (f) using a low-pass filter or the like and extracting the low frequency components, it is possible to extract only the track crossing signal, and based on this extracted track crossing signal It was possible to move the optical head (f) to an appropriate position.

[Problems to be Solved by the Invention] However, when the track access speed is increased, the frequency component included in the track crossing signal generated when the optical head (f) crosses the pregroove (a) becomes high, and recording The frequency difference between the recording signal and the recording signal generated at the dot (h) portion becomes smaller, making it difficult to separate both signals in terms of frequency, making it impossible to accurately extract the track crossing signal and making access errors more likely. There was a drawback.

For this reason, there is a problem that there is a limit to the track access speed and it is not possible to increase the track access speed.

[Means for Solving the Problems] The present invention has been made in view of the above problems, and its object is to provide a track access method that can speed up track access without causing access errors. It's about doing.

That is, the present invention is based on an optical recording and reproducing device that optically records and reproduces information, or records and erases information by converging focused light from a light source on the converging surface of an optical recording medium via an optical head, An optical head is moved in a direction across the recording tracks and non-recording areas of an optical recording medium in which a plurality of recording tracks and non-recording areas with different conditions are provided alternately, and recording is reproduced when the optical head crosses the recording tracks. signal and a track crossing signal generated when the optical head crosses a non-recording area, extract only the track crossing signal from the difference in reflected light level between the recorded signal and the track crossing signal, and extract this extracted signal. The present invention is characterized in that the position of the optical head is controlled based on a track crossing signal.

In such a technical means, the optical recording medium may have any structure as long as it has a plurality of alternating recording tracks and non-recording portions having mutually different reflection conditions. Further, the degree of difference in the reflection conditions between the recording track and the non-recording portion is arbitrary as long as it is possible to differentiate the reflected light amount level of the recording signal and the track crossing signal obtained from each portion.

In addition, as a means of creating a difference in the reflection conditions between the recording track and the non-recording area, there is a method of creating a phase difference in the reflected light from each part to create a difference in the level of the amount of reflected light, A method of varying the reflectance itself can be used.

A specific example of an optical recording medium in which the former method is applied to create a phase difference between the recording track and the reflected light from the non-recording area is a non-recording area formed by a pregroove on at least one side of the substrate. It is possible to use a recording medium, etc., which is provided with a recording track formed by a recording area between the non-recording portions and in which recording pits are formed, and in which the pregroove and the recording pit have different depth dimensions.

On the other hand, as a specific example of an optical recording medium in which the latter method is applied to provide a difference in reflectance between recording tracks and non-recording areas, a recording medium having the following configuration can be used. For example, a low-reflectivity substrate, a plurality of recording tracks formed of band-shaped recording layers at intervals on at least one surface of the substrate, and a plurality of low-reflection areas where the recording layer does not exist between these recording tracks. Another example is a recording medium having a highly reflective substrate, a plurality of recording tracks formed of strip-shaped recording layers at intervals on at least one surface of the substrate, and the like. A recording medium having a plurality of non-recording areas, which are high reflection areas where the recording layer does not exist, between the recording tracks can be used. In the latter case, the substrate may be replaced with a highly reflective substrate by coating the substrate with a highly reflective material.

The substrate further includes a recording layer provided on the entire surface of at least one side of the substrate, and a low-reflectivity rough surface portion provided at intervals on the recording layer, and a plurality of non-recording portions formed by the substrate and the rough surface portion. It is also possible to use a recording medium having a plurality of recording tracks formed of a recording layer exposed from between the non-recording portions and the non-recording portions.

Further, as a means for extracting only the track crossing signal from the difference in reflected light amount level between the recording signal and the track crossing signal, for example, the following method using a level comparator can be used.

That is, when the light intensity level of the track crossing signal is low, the reference voltage (2) of the level comparator is set higher than the lowest value (2)TC of the track crossing signal from the non-recording section, while the recording signal (2) from the recording track is set. By setting it to be lower than □, only the track crossing signal can be extracted.

Note that the conventional method can be applied as is to the means for controlling the position of the optical head based on the extracted track crossing signal.

Here, regarding the substrate constituting a part of the optical recording medium, in the case of a type in which focused light is irradiated from the substrate side, it is made of a light-transmitting material such as glass, polycarbonate, polyacrylonitrile, polymethyl methacrylate, or epoxy resin. However, in the case of a type in which the light is emitted from the opposite side of the substrate, it may be made of a light-opaque material. Furthermore, this technical means can be applied to any optical recording medium that has recording tracks and non-recording areas with different reflection conditions, so it can also be used for substrates that do not have pregrooves.

In addition, the recording material constituting the recording track is as follows:
All materials commonly known as optical recording materials can be used.

That is, Te, Se, S, Sb, As, P.

Pb, Sn, Ge, Si, TI, In, Ga, A
I, ZnSAu, Ao, CuSPt, Mo, Ti, Ni
A single substance or a compound containing at least one component of elements such as , Or, and W, or a material in which these elements are dispersed in another material can be used. Among these, Te, 5e-Te1Pb-8e-Te, Te-C, etc. are non-rewritable recording pit forming types, that is, hole drilling is suitable for the mold material, and Teox, TeOx (Ge, S
n addition),) n-3e, In-8b, In-Te, Sb
25e1Te-Ge-8n, Te-Ge-8n-ALI
, AS S 5b-Te.

23 notes Te-N, Ge-Te, Aq-1n5Aq-Zn, Cu
-Am Aq-Aj-Cu, Cu-Aj-Ni, Au-
Ti, cr-T+, etc. are suitable for phase change recording materials that are rewritable recording/reproducing/erasing type.

In addition, rewritable magneto-optical recording materials include Fe1Co,
Transition metals such as N+ and vn, and Tb and Gd.

Nd, Pm, Sm, En, Dy, Ho, Er.

A magnetic material containing at least one component of rare earth elements such as Tm, 'y'b, and lu, typically Tb-1:e-
Go, Tb-Fe, DV-Fe, Mn-B i , Pt
-Mn-8b etc. can be applied.

Furthermore, as materials constituting the recording layer, in addition to the above, organic dye materials such as cyanine dyes, phthalocyanine, naphthoquinone, squarylium, polythiophene, and polydiacetylene, as well as spiropyran, fulgide, azobe,
Photochromic materials typified by carbon dioxide and the like can be used.

Note that the light source used in conventional methods can be used as a light source for recording/reproducing information or recording/reproducing/erasing information by irradiating the recording layer of the optical recording medium with focused light. GaAlAs semiconductor laser, GaAII
Semiconductor lasers such as nP semiconductor lasers and Ga1nAsP semiconductor lasers, He-Na lasers, A lasers, H
Examples include gas lasers such as e-Cd lasers.

[Operation] According to the above-mentioned technical means, an optical head is moved in a direction across recording tracks and non-recording areas of an optical recording medium in which a plurality of recording tracks and non-recording areas having mutually different reflection conditions are provided alternately. Since the recording signal from the recording track and the track crossing signal from the non-recording area are obtained by moving the recording track, the difference in the level of reflected light between the recording signal and the track crossing signal may occur due to the difference in the reflection conditions between the recording track and the non-recording area. can be made larger.

Therefore, it is possible to extract only the track crossing signal from this reflected light amount level difference, so it is possible to reliably control the position of the optical head based on the extracted track crossing signal.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

◎First Example The optical recording medium (1) applied to this example is shown in Figs.
As shown in Figure 2, concentric pregrooves (2
), a recording film made of Aj (4) provided on one entire surface of this substrate (3), and a polycarbonate film (4) provided on the entire surface of this recording 1m (4). Am Meiho r! ! The main part of the film (5) is composed of a plurality of non-recording parts (6) made of the pregroove (2), and a recording area between the non-recording parts (6). It has a plurality of recording tracks (8) in which pits (7) are formed.

Further, the depth dimension (d) of the pregroove (2) is set to 1/4λ as shown in FIG. 3, where λ is the wavelength of the laser light from the semiconductor laser (90) that is the light source. On the other hand, the depth dimension (d') of the recording pit (7) formed in the recording track (8), that is, the recording layer (4)
The thickness dimension (do) is set to 115λ to 1/6λ,
The amount of light reflected from the pregroove (2), which is the non-recorded portion (6), is adjusted to be smaller than the amount of light reflected from the recording pit (7).

That is, when the depth dimension (d) of the pregroove (2) is set to 1/4λ as shown in FIG. 4, the reflected light (β) from the pregroove (2) Since the phase of the reflected light (α) from the pregroove (2) is delayed by 2xd=2X(1/4λ)=1/2λ, as shown in Figure 5, the reflected light (β) from the pregroove (2) phase and its surrounding recording track (
The phase of the reflected light (α) from 8) is opposite to that of the reflected light (α), and the reflected light cancels out and forms the pregroove (2) as shown in Figure 6.
The total amount of light reflected from the is minimized.

In contrast, the depth dimension (do) of the recording pit (7)
is set to 115λ to 1/6λ, and the phase shift of the reflected light from the recording pit (7) compared to the reflected light (α) from the recording track (8) is 2xd=2x(1
15λ ~ 1/6λ) - 215λ ~ 1/3λ, and the phase is not reversed, so the amount of reflected light decreases to a small degree, and as shown in Figure 6, the amount of reflected light is higher than the amount of total reflection from the pregroove (2). It will be shown.

In addition, FIG. 7(A) shows a distribution diagram of the amount of reflected light from the optical recording medium (1) when the optical head (9) is moved, that is, an output distribution diagram of the amplified read signal. Reflected light 1 (R
1) is maximum and the read signal is vHAX, while the reflected light from the non-recording area (6) consisting of the pregroove (2), that is, the track crossing signal (STC).
The reflected light ff1 (R2) is the minimum and the lowest value of the read signal is vTC, which is the reflected light from the recording pit (7) of the recording track (8), that is, the reflected light of the recording signal (S, 1). ! (R3) is in the middle, and the lowest value of its read signal is ■. 1 can be understood.

On the other hand, as shown in FIG. 1, the optical recording and reproducing apparatus according to this embodiment includes a semiconductor laser (90) as a light source and an optical head that is movably provided and equipped with a condensing lens (not shown). (9), a beam splitter (91) that separates the laser beam from the semiconductor laser (90) and the reflected light from the optical recording medium (1), and converts the separated reflected light into a servo signal such as a focus error signal. A servo signal detector (92) for obtaining a reproduction signal and a reproduction signal receiver (92) for obtaining a reproduction signal.
The main part thereof is composed of a half mirror (94) that divides the light into the optical recording and reproducing apparatus.As shown in the block diagram of FIG. , an optical head (9), and an amplifier (
10), a track crossing signal extraction circuit (11) which receives the amplified read signal and extracts only the track crossing signal (S, .) from the read signal, and the extracted track crossing signal (S□.). A track counter (1) is input and counts the number of signals.
2), a comparison circuit (14) which receives the data signal of the counted number of track crossing signals and the track designation signal from the control circuit (13) and outputs a comparison data signal from each signal, and this comparison data signal. The main part thereof is composed of a servo circuit (15) which changes the position of the optical head (9) so that the data signal of the number of track crossing signals and the track designation signal coincide with each other.

In addition, the track crossing signal extraction circuit (11)
consists of a level comparator (16) whose negative input terminal is supplied with a read signal from the amplifier (10) and whose positive input terminal is supplied with a reference voltage vR, and the reference voltage VR is As shown in Figure 7 (A), the lowest value of the track crossing signal (S□.) is
) is V, □C, then V > V > V ding CDT
It is set to a value that satisfies the range of R.

The read signal from the amplifier (10) is also supplied to a reproducing circuit (not shown), and the recording signal (
So,) is now played.

As shown in FIG. 1, the optical recording/reproducing device configured in this manner moves the optical head (9) in the radial direction of the optical recording medium (1) using a head actuator (not shown) or the like during track access. , the reflected light from the optical recording medium (1) is passed through the optical head (9) to the reproduced signal receiver (9).
Detected in 3).

The detected reflected light, ie, the read signal, is input to the amplifier (10), amplified, and output to the track crossing signal extraction circuit (11).

Here, the read signal output from the amplifier (10) includes:
Track crossing signal (S,.) and recording signal (S,
□), but the small rack crossing signal (S, .) is based on the reflected light from the pregroove (2) set to a depth of 1/4λ, as shown in Figure 7(A). As shown in , the lowest value of the read signal is vTC, whereas the recorded signals (S, T) are based on the reflected light from the recording pit (7) set at a depth of 115λ to 1/6λ. The lowest value of the read signal is the lowest value of the track crossing signal (S, .). ■ Higher value. It is 1.

For this reason, the track crossing signal extraction circuit (11)
, and its reference voltage ■8 is ■ >■R> V
When the above read signal is input to the level comparator (16) set to IC T, the track crossing signal extraction circuit (11)
The output signal from the track crossing signal (S, . . . ) corresponds to the track crossing signal (S, . . . ) as shown in FIG. 7(B).

Therefore, based on the track crossing signal (STo) extracted by the track crossing signal extraction circuit (11), the track counter (12) and the comparison circuit (14)
), and the optical head (9) by the servo circuit (15).
) position control can be performed with high precision, the track access speed can be increased, and the track crossing signal (
S. Even if the frequency of ) approaches the frequency of the recording signal (S, □), only the track crossing signal (S) can be reliably extracted, which has the advantage of enabling high-speed track access.

O Second Example The optical recording medium (1) applied to this example is a circular glass substrate (3) having a concentric pregroove (2) on its surface as shown in FIG. And this board (3)
Phase change type TeOx record 1 provided on one side of the entire surface!
! (4) and the polycarbonate transparent protection 1 provided on the entire surface of this recording film (4)! ! (5), a plurality of non-recording areas (6) consisting of the pregroove (2), and a plurality of recording areas consisting of recording areas between the non-recording areas (6). It has a track (8).

Further, the depth dimension of the pregroove (2) is set to 1/4λ as in the first embodiment, so that the amount of reflected light from the pregroove (2), which is the non-recording part (6), is reduced. It has been adjusted.

On the other hand, in the phase-changed recording dot (80) of the recording track (8), the reflectance of that part changes in the direction of increasing, so that it can be distinguished from the non-recorded part (6) with less reflected light. The track access device in the first embodiment can be applied as is.

Also in this embodiment, when the optical head (9) is moved during track access as shown in FIG. 10(A), a read signal having a reflected light amount distribution as shown in FIG. 10(B) is obtained. Therefore, by inputting the read signal to the track crossing signal extraction circuit (11) similar to the first embodiment, an output corresponding to the track crossing signal (S, .) as shown in FIG. 10(C) can be obtained. (q) and this extracted track crossing signal (STc
), the position of the optical head (9) can be controlled with high precision, and high-speed track access is possible.

◎Third Embodiment The optical recording medium (40) applied to this embodiment differs from the first embodiment in which the depth dimensions of the pre-groove and the recording pit are changed to give different reflection conditions. The recording sections have different reflectances to provide different reflection conditions.

That is, as shown in FIG. 11, this optical recording medium (40) includes a circular glass substrate (41) with a smooth surface, and a Te0
The main part thereof is composed of a recording track (43) formed by a band-shaped recording 1iffi (42) made by X and a transparent protective film (44) made by 5io2 provided on the entire surface of one side of the substrate (41), and Recording W between the above recording tracks (43)
The non-recording area (
45) is formed. Incidentally, the reflectance in the recording track (43) was about 20% to 50%, whereas the reflectance in the non-recording part (45) was about 5%, and the reflection conditions were significantly different.

Further, in the optical recording medium (40) according to this embodiment, the non-recording area (45) is configured with a low reflection area, and the amount of light reflected from this area is extremely large compared to the amount of light reflected from the recording track (43). Therefore, the track access device in the first embodiment can be applied as is.

Also in this embodiment, when the optical head (9) is moved during track access as shown in FIG. 12(A), a read signal having a reflected light amount distribution as shown in FIG. 12(B) is obtained. Therefore, by inputting the read signal to the track crossing signal extraction circuit (11) similar to the first embodiment, an output corresponding to the track crossing signal (S, .> as shown in FIG. 12(C)) can be obtained. is obtained, and this extracted track crossing signal (S□.

), the position of the optical head (9) can be controlled with high precision, and high-speed track access is possible.

In this example, an optical recording medium (40
), you can also use the configuration shown below.

That is, as shown in FIG. 13, concentric grooves (50
) and a concave groove (5).
The main part thereof is composed of a recording track (52) formed of Te0X deposited on the substrate (51) and a transparent protective film (53) made of SiO2 provided on the entire surface of one side of the substrate (51), and , an optical recording medium in which a low-reflectivity non-recording part (55) is formed by a convex groove (54) between the grooves (50), and a concentric groove (54) on the surface as shown in FIG. 50)
A circular glass substrate (51) provided with a recording track (52) formed of Te0X deposited in the groove (50), and a recording track (52) formed of Te0X formed on one entire surface of the substrate (51). However, the main part is composed of the aluminum reflective film (56), and the convex groove (54) between the grooves (50) is
Therefore, an optical recording medium or the like in which a highly reflective non-recording portion (55) is formed can be used.

Further, as shown in FIG. 15, a circular glass substrate (61) on which a concentric rough surface area (60) is formed, and a recording layer uniformly provided on this substrate (61). (62
) and a SiO2 protective film (63) uniformly provided on the surface of the recording If (62) side substrate (61), and the recording layer (62) has the above-mentioned roughness. Surface area (
60), and a low-reflectivity non-recording area (65) formed based on the rough surface area (64), and a smooth area (66) between the rough area (60). The optical recording medium may include a highly reflective recording track (61).

[Effects of the Invention] As described above, according to the present invention, an optical head is moved in a direction across recording tracks and non-recording areas of an optical recording medium in which a plurality of recording tracks and non-recording areas having different reflection conditions are provided alternately. Since the recording signal from the recording track and the track crossing signal from the non-recording area are obtained by moving the The difference can be increased.

Therefore, only the track crossing signal can be extracted from this reflected light level difference, and based on this extracted track crossing signal, the position of the optical head can be controlled with high precision, and the track access speed can be further increased. Even when the frequency of the track crossing signal approaches the frequency of the recording signal, only the track crossing signal can be reliably extracted, which has the effect of speeding up track access.

[Brief explanation of the drawing]

1 to 15 show embodiments of the present invention.
The figure is a perspective view of the optical recording medium according to the first embodiment, FIG. 2 is a partially sectional perspective view thereof, FIG. 3 is a partially enlarged view of FIG. 2, and FIG.
The figure is a cross-sectional view of Figure 3, Figure 5 is a waveform diagram of reflected light from the optical recording medium, Figure 6 is a diagram of the relationship between the depth of pregroove and recording pits and the amount of total reflected light, and Figure 7 (A). 7 is a distribution diagram of the amount of reflected light from the optical recording medium during track access.
FIG. 8B shows a waveform diagram of the extracted track crossing signal, and FIG. 8 shows a basic block diagram of the track access device incorporated in this optical recording/reproducing device.
FIG. 9 is a perspective view of the optical recording medium according to the second embodiment;
Figure 10 (A) is an enlarged partial plan view of the optical recording medium, Figure 10 (B) is a distribution diagram of the amount of reflected light from the optical recording medium during track access, and Figure 10 (C) is a diagram of the extracted track crossing signal. FIG. 11 is a perspective view of an optical recording medium according to the third embodiment, FIG. 12(A) is an enlarged partial plan view of the optical recording medium, and FIG. 12(B) is a track access diagram. Fig. 12 (C) shows a waveform diagram of the extracted track crossing signal, and Figs. 16 to 19 show conventional examples, FIG. 16 is a perspective view of the optical recording medium, FIG. 17 and FIG.
FIG. 8 shows a partially enlarged perspective view thereof, and FIG. 19 shows an explanatory view of the optical recording/reproducing apparatus at the time of reproduction. [Description of symbols] (1)...Optical recording medium (2)...Pregroove (3)...Substrate (6)...Non-recording area (7)...Recording pit (8)...・Recording track (9)...Optical head (11) (30)...Track crossing signal extraction circuit patent Applicant: Fuji Xerox Co., Ltd. Representative Patent attorney: Tomohiro Nakamura (3 others) No. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 9 Fig. 10 (C) Fig. 11 Fig. 12 (C) Ear L■] L■ - Fig. 16 Fig. 17

Claims (5)

[Claims] (1) In an optical recording and reproducing device that optically records and reproduces information, or records and erases information by converging focused light from a light source on the converging surface of an optical recording medium via an optical head, recordings with different reflection conditions are used. An optical head is moved in a direction across the recording tracks and non-recording areas of an optical recording medium in which a plurality of tracks and non-recording areas are provided alternately, and a recording signal reproduced when the optical head crosses the recording track, and an optical The track crossing signal generated when the head crosses the non-recording area is determined, and only the track crossing signal is extracted from the difference in the level of reflected light between the recording signal and the track crossing signal, and the extracted track crossing signal is A track access method in an optical recording/reproducing apparatus, characterized in that the position of the optical head is controlled based on the above. (2) The optical recording medium has a plurality of non-recording areas formed by pregrooves provided on at least one side of the substrate, and a plurality of non-recording areas in which recording pits are formed between the non-recording areas. A track according to claim 1, characterized in that the track has a recording track, and the depths of the pregroove and the recording pit are changed to provide a difference in reflection conditions between the non-recording part and the recording track. how to access. (3) The optical recording medium includes a plurality of recording tracks formed of a recording layer at intervals on at least one side of the substrate, and the plurality of non-recording areas are formed of low reflection areas between the recording tracks. A track access method according to claim 1, characterized in that: (4) The optical recording medium has a plurality of recording tracks formed by a recording layer at intervals on at least one side of the substrate;
This recording track and a highly reflective film laminated on the exposed surface of the substrate and having a higher reflectance than the recording track are provided, and the plurality of non-recording portions are constituted by highly reflective areas between each recording track. A track access method according to claim 1, characterized in that: (5) The optical recording medium includes a recording layer provided on at least one entire surface of the substrate, and the plurality of non-recording portions are formed of low-reflectivity rough surface portions formed at intervals on the recording layer. A track access method according to claim 1, characterized in that: