JP2755355B2 - Information recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an information recording medium for optically recording and reproducing information.

2. Description of the Related Art An information recording medium for optically recording, reproducing, and erasing information performs writing and reproduction of information by utilizing the interaction between light and an optical recording material, and is generally well known as an optical disk. .

Conventionally, read-only, write-once, and rewritable types have been put into practical use as information recording media, and media in which a read-only area and a recordable area are formed on the same medium are being developed.

By the way, when used as a storage device such as a computer, if a read-only area and a recordable area are formed on the same medium, for example, a word processor system program is stored in the reproduction area, and a document file is provided in the recording area. System and documents can be stored on a single disk. In the case of a medium having two areas, when a guide groove for an information recording area and a guide groove for an information reproduction-only area having a pit structure are formed on the same substrate, the width of the guide groove in the information recording area, The groove width of the guide groove in the dedicated area is the same.

The prior art will be described with reference to the drawings. FIG. 5 shows a conventional information recording medium having a read-only area and a recordable area on the same medium. That is, in FIG. 5, 1 is a groove in the information recording area, 2 is a groove between the information recording areas,
Reference numeral 3 denotes a groove in the read-only area, and reference numeral 4 denotes a pit.

Regarding the information recording medium of the prior art having the above configuration,
The operation will be described below.

A medium having two areas including an information reproduction-only area 6 and an information recordable area 5 is provided on the same substrate.
And a guide groove 3 of an information reproducing area 6 having a pit 4 structure. The width W ₂ of the guide groove 1 of the information recording area 5 and the groove width of the guide groove 3 of the information reproducing area 6 are formed. relationship width W ₁ had a structure that is substantially W ₂ = W _1.

[Problems to be Solved by the Invention] However, if the groove width of the guide groove in the information recording area is the same as the groove width of the guide groove in the information read-only area, when recording, reproducing, and erasing information between the grooves, However, when focusing is performed between the grooves, there is a problem that the tracking error signal is reduced in the information reproduction-only area having the pit structure, and it becomes necessary to control the gain. That is, as shown in FIG. 6, the information compared to the tracking error signal V ₂ of the recording area, the smaller the tracking error signal V ₁ of the information read only area 6, as a result, control of the gain becomes necessary.

An object of the present invention is to provide an information recording medium capable of making a tracking error signal in an information recording area and a tracking error signal in an information reproduction-only area having a pit structure substantially equal in size in order to solve the above-mentioned problem of the prior art. With the goal.

[Means for Solving the Problems] To achieve the above object, an information recording medium of the present invention comprises:
An information recording medium for optically recording / reproducing information, wherein a guide groove of an information recording area and a guide groove of an information reproduction-only area having a pit structure are formed on the same substrate. The groove width is different from the groove width of the guide groove in the information reproduction-only area.

In the configuration of the present invention, when the groove width of the guide groove in the information-only area is W ₁ and the groove width of the guide groove in the information-recording area is W ₂ , the relationship W ₂ <W ₁ <2W ₂ holds. It is more preferable to form the guide groove as described above.

[Operation] According to the configuration of the present invention described above, since the groove width of the guide groove of the information recording area and the groove width of the guide groove of the information-only area are made different, the tracking error signal of the information recording area is formed. Thus, an information recording medium can be realized in which the tracking error signal of the information read-only area having the pit structure can be made substantially equal in magnitude.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional cutaway view of an information recording medium according to one embodiment of the present invention. In FIG. 1, 1 is a groove in an information recording area, 2 is a groove between information recording areas, 3 is a groove in a reproduction-only area, 4 is a pit, 5 is an information recording area, and 6 is an information reproduction-only area.

The operation of the information recording medium having the above configuration according to one embodiment of the present invention will be described below.

A medium having two areas including an information reproduction-only area 6 and an information recordable area 5 is provided on the same substrate.
And a guide groove 3 in an information reproduction-only area 6 having a pit 4 structure. Then, a groove width W ₂ of the guide grooves 1 of the information recording area 5, the information read only area 6
With different groove width W ₁ of the guide groove 3 of formed.

By doing so, as shown in FIG. 2 may be approximately equal in magnitude to the tracking error signal V ₁ of the information read only area with a tracking error signal V ₂ and the pit structure of the information recording area.

Next, FIG. 4 shows the relationship between the groove width and the tracking push-pull signal modulation degree. This is the tracking push-pull signal modulation degree when the track pitch is 1.6 μm as an example. In FIG. 4, if the reflectance of the mirror portion of the information recording medium is I _O and the push-pull signal is I _PP , the tracking push-pull signal modulation degree is defined by I _PP / I _O and the groove width is 0 to 0.8. It can be seen that in the range of μm, the tracking push-pull signal modulation monotonically increases with respect to the groove width, and takes the maximum value when the groove width is 0.8 μm. Therefore, in order to further increase the tracking error signal, it is preferable to increase the groove width. For example, the groove width W ₂ of the information recording area is good when set to be I _PP / I _O = 0.4~0.65, particularly, the groove width W ₂ of the information recording area, 0.4-0.5
μm was optimal.

On the other hand, in the information recording / reproducing area,
A pit of about 1300 mm is formed, and when a guide groove having the same groove width as the information recording area is formed, as shown in FIG. An attempt was made to increase the error signal. As shown in FIG. 3, an area exclusively for reproducing information was formed on the inner side of the substrate, and an information recording area was formed on the outer side of the substrate. In this case, the groove width W ₂ of the information recording area, during the information read only area groove width W ₁ of, W ₂ <W ₁ <forming a guide groove so 2W ₂ the relationship is established, the first view Such an information recording medium was created. Groove width of information-only area
W ₁ is a tracking push-pull signal modulation degree from Figure 4 is set in a range obtained degree 0.7 to 0.8, W ₁ = 0.7 [mu] m, W
₂ = 0.5 μm. By increasing the groove width, the gap between the pits is narrowed, but by setting the depth (d = λ / 4) so that the modulation degree of the pit is maximized, the contrast of the signal is reduced. We can take enough. As a result, the C / N of the pit does not decrease even if the gap between the grooves becomes narrow.

When a width of W ₂ = W ₁ = 0.5 μm is formed as shown in FIG. 5, the tracking error signal V ₁ in the read-only area is clearly reduced as shown in FIG. by widening the groove width, as shown in FIG. 2, a tracking error signal V ₂ of the information recording area, a tracking error signal V ₁ of the information read only area was confirmed that the equal.

As described above, according to this embodiment, by setting the groove width of the guide groove in the information recording area to be wider than the groove width of the guide groove in the information recording area, the information recording area and the information recording area are formed on the same substrate. Even when the area was formed, an information recording medium was obtained in which the tracking error signal of the information recording area and the tracking error signal of the information recording area could be made substantially the same. As a result, the tracking servo can be made extremely stable, and the gain control can be made unnecessary.

[Effects of the Invention] As described above, according to the present invention, since the groove width of the guide groove in the information recording area and the groove width of the guide groove in the information-only area are different, the information is formed on the same substrate. To provide an information recording medium capable of making a tracking error signal of an information recording area and a tracking error signal of an information reproduction only area having a pit structure substantially equal in size even when a recording area and an information recording only area are formed. The special effect that can be achieved can be achieved.

Further, in a preferred configuration of the present invention, when the groove width of the guide groove in the information-only area is W ₁ and the groove width of the guide groove in the information-recording area is W ₂ , the relation W ₂ <W ₁ <2W _{2 is} satisfied. By forming the guide groove so that the following holds, the tracking error signal of the information recording area and the tracking error signal of the information reproduction-only area can be made more equal.

[Brief description of the drawings]

1 is a cutaway view of an information recording medium according to an embodiment of the present invention, FIG. 2 is a diagram showing a tracking error signal of the information recording medium of FIG. 1, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a diagram showing the relationship between the groove width and tracking push-pull signal modulation, FIG. 5 is a cross-sectional cutaway view of a conventional information recording medium, and FIG. FIG. 3 is a diagram illustrating a tracking error signal of the information recording medium of FIG. 1 ... grooves in the information recording area, 2 ... between grooves in the information recording area,
Reference numeral 3 represents a groove in a reproduction-only area, 4 represents a pit, 5 represents an information recording area, and 6 represents an information reproduction-only area.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) G11B 7/24 G11B 7/00

Claims (2)

(57) [Claims] An information recording medium for optically recording / reproducing information, wherein a guide groove in an information recording area and a guide groove in an information read-only area having a pit structure are formed on the same substrate. An information recording medium, wherein the groove width of the guide groove in the area is different from the groove width of the guide groove in the information reproduction-only area. 2. When the groove width of the guide groove in the information reproducing area is W ₁ and the groove width of the guide groove in the information recording area is W ₂ , the guide is established such that the relation W ₂ <W ₁ <2W ₂ is established. 2. The information recording medium according to claim 1, wherein the groove is formed.