JPH07161045A - Optical disk and optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To simplify the structure of an optical disk device and to contrive miniaturization and low cost of the device. CONSTITUTION:Information is recorded and reproduced in grooves 1a,... and lands 1b,..., an in order to record address information at the time of molding the optical disk, the grooves 1a,... are formed in wobbling, while the lands 1b,... are formed with pits 1c,... Thus, the optical disk 1 is made to be inexpensive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc for recording and reproducing information by using a laser beam, and an optical recording and reproducing device for recording and reproducing information on this optical disc.

[0002]

2. Description of the Related Art Conventionally, various methods for recording / reproducing information below the optical resolution of a pickup of an optical recording / reproducing apparatus have been proposed in order to increase the density of optical discs.

For example, Japanese Patent Application Laid-Open No. 5-81717 discloses that
In an optical disc utilizing the magneto-optical effect, a method is disclosed in which a magnetic layer is provided on a perpendicularly magnetized film and recorded information is masked to eliminate information crosstalk from adjacent tracks, thereby increasing information density. ing.

In the above method, it is possible to read information below the resolution of the light spot, but the resolution of the tracking error signal for reading the information of the light spot is
It depends on the size of the light spot. For this reason, since a tracking error signal having a resolution lower than that of the light spot cannot be detected accurately, the rotation of the optical disk cannot be controlled accurately, and information cannot be recorded / reproduced accurately.

Further, Japanese Patent Application Laid-Open No. 63-57859 discloses a method for increasing the density of information by recording / reproducing information on / from both the land and the groove of an optical disk. A soft format method has been proposed as a format method of an address signal for information management on an optical disk by a method of recording and reproducing information on both the land and the groove.

However, in the above soft format method, when the optical disc is used for the first time, the address signal is formed by the initial format in the optical recording / reproducing apparatus. Therefore, the reference signal for controlling the rotation of the spindle motor at the initial format is used. Is required separately. For this reason,
The inside of the device becomes complicated, resulting in an increase in size and cost of the device.

Therefore, as another method of formatting an address signal for information management, for example, as shown in FIG. 6, a groove 21a ... And a land 21b ... As a track for guiding a light source formed on an optical disk 21. In both of them, there is proposed a method of formatting an address signal by forming pits 21c ... At the time of molding an optical disk. According to this method, since the address signal is pre-formatted (pre-formatted) at the time of molding the optical disc, it is not necessary to perform the initial formatting in the device, and it is not necessary to provide a member for the initial formatting, and the device configuration is improved. It can be simple. Further, by recording / reproducing information on / from both the groove 21a and the land 21b of the optical disc 1, it is possible to increase the information density.

As another address signal pre-formatting method, for example, Japanese Patent Application Laid-Open No. 64-35727 discloses a method of forming a groove by wobbling and formatting the address signal at this time.
Even in this case, the address signal does not need to be soft-formatted, and the configuration of the device can be simplified.

[0009]

However, when the address signal is formatted by forming the pits 21c ... In the grooves 21a ... And the lands 21b ... Of the optical disk 21, the optical disk 21 will be formatted as shown in FIG. 7 (a). , There are portions where the pits 21c ... Are not formed, and portions where the pits 21c are formed, as shown in FIGS. 7B, 7C and 7D. Therefore, the depths from the reference height of the pits 21c formed in the grooves 21a and the lands 21b are different, so that it is necessary to form pits of two kinds of depths. For this reason, the process for forming the pits 21c ... Of the optical disk 21 becomes complicated, which complicates the entire manufacturing process.

Further, the optical disk 21 has a CLV (Cons
When a track is formed by the tant Linear Velocity (constant linear velocity) method, the track is formed in a spiral shape, and therefore the address signals formed by the preformat method are not on the same radius.
If the track E of is traced by a light spot,
As shown in (a) and (b), when the pit 21c, that is, the address signal does not exist in both adjacent tracks, as shown in FIG. 7C, the address signal exists in both adjacent tracks. In this case, as shown in FIG. 7D, the address signal may exist in only one of the adjacent tracks. Therefore, the intensity of the address signal due to the light spot changes in each case, which makes address management difficult.

Further, as shown in FIG. 7 (d) above,
When the address signal exists only on one of the tracks adjacent to the track E, the pits are asymmetrical with respect to the read track, so that an offset occurs in the tracking error signal and the tracking servo control is not accurately performed, and the reproduction is performed. The signal quality is degraded.

Further, in the method of managing the address signal of the groove by the wobbling method, the address signal of the groove is formed by the pre-formatting method, but the address signal of the land cannot be pre-formatted. Therefore, the address signal is applied to the land. Formatting must be performed by a soft format method, which requires an apparatus for this purpose, which causes a problem of increasing the manufacturing cost of the optical recording / reproducing apparatus.

The present invention has been made in view of the above problems, and an object thereof is to provide an optical disc in which an address signal is preformatted in both a groove and a land, and an offset does not occur in a tracking error signal. Another object of the present invention is to provide an optical recording / reproducing apparatus capable of accurately recording / reproducing information on / from this optical disc.

[0014]

An optical disc according to claim 1 is an optical disc in which information is recorded and reproduced on both a groove and a land forming a track for guiding a light beam from a light source. At the time of molding, in order to record address information, the above groove is
It is characterized in that it is formed by wobbling and pits are formed in the land.

An optical recording / reproducing apparatus according to a second aspect of the present invention includes an optical head for recording / reproducing information on / from both the groove and the land of the optical disc according to the first aspect, and a disc driving means for rotationally driving the optical disc. At the time of recording / reproducing information recorded on the optical disk, the groove manages the address information recorded in the groove by the light modulation signal by wobbling, and the land is recorded in the land by the light modulation signal by pits. And a control means for managing the address information and controlling the disk drive means based on the wobbling frequency information.

Further, in the optical recording / reproducing apparatus of the third aspect, in the optical recording / reproducing apparatus of the second aspect, the optical head is provided with a light receiving means for receiving the reflected light from the optical disk and converting it into an electric signal. The light receiving means has a light receiving area divided into at least two parts in a direction parallel to the track of the optical disk, and at the time of recording / reproducing information to / from the groove of the optical disk, a difference in electric signal from the two light receiving areas. It is characterized in that the address information recorded on the optical disc is discriminated by detecting the motion signal and detecting the sum signal of the electric signals from the two divided light receiving areas at the time of recording / reproducing information to / from the land. .

[0017]

According to the structure of the first aspect, the address signal is pre-formatted by wobbling in the groove and the address signal is pre-formatted by the pit in the land when the disc is molded. As a result, when formatting the address signal to both the groove and the land, it is not necessary to perform the initial formatting in the optical recording / reproducing device after molding the disc as in the soft formatting, and this allows the device to pre-format. Need not be provided, and a reference signal used for rotation control of a spindle motor as a drive means of an optical disc at the time of formatting is not required. As a result, the optical recording / reproducing device for recording / reproducing information by using the optical disc having the above-described structure has a simple structure, and the size and cost of the device can be reduced.

In the groove, the address signal is formed by wobbling, and in the land, the address signal is formed by pits. Therefore, when the land is traced, there is no pit in the adjacent track, that is, the groove. Therefore, the intensity of the address signal does not change depending on the adjacent track, and an accurate tracking error signal can be obtained. As a result, no offset occurs in the tracking error signal, and tracking servo can be performed accurately.

Further, since the wobbling frequency of the adjacent groove can be detected at the time of tracing the land of the optical disk, this wobbling frequency can be applied to the rotation control of the drive means such as the spindle motor, and the CLV control of the optical disk. Can be easily performed on both the groove and the land.

According to a second aspect of the present invention, the control means controls the recording / reproducing of the information recorded on the optical disc.
In the groove, the address information recorded in the groove is managed by the light modulation signal by wobbling, and also
Since the land manages the address information recorded on the land by the light modulation signal of the pits, the address information recorded on the groove and the land of the optical disk can be managed by a simple method. by this,
The structure of the device can be simplified, and the size and cost of the device can be reduced.

Further, since the control means controls the disk drive means based on the wobbling frequency information, when the information is recorded / reproduced with respect to both the groove and the land, the disk rotation is accurately performed. The drive means can be controlled. As a result, the optical disc can be stably rotated with a simple structure, so that the size and cost of the device can be reduced.

Further, according to the third aspect of the present invention, the control means detects the differential signal of the electric signal from the two light receiving areas of the light receiving element at the time of recording / reproducing information to / from the groove of the optical disc, Further, at the time of recording / reproducing information on / from the land, the address information recorded on the optical disc can be discriminated by detecting the sum signal of the electric signals from the light receiving area divided into two. As a result, the address information recorded on the optical disk can be easily obtained only by detecting the differential signal or the sum signal of the electric signals from the light receiving element. Therefore, since the groove and land address signals can be clearly distinguished and detected, crosstalk between the address signals of adjacent tracks can be eliminated. Further, since the address signal of the optical disc can be stably reproduced by a simple method, information can be accurately recorded / reproduced without requiring a complicated mechanism. As a result, the device can be downsized and reduced in size. The price can be increased.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

As shown in FIGS. 1 and 2A, the optical disc 1 according to the present embodiment is sandwiched between the grooves 1a which are wobbled to improve the recording / reproducing density and the grooves 1a. Information is recorded / reproduced on / from both the lands 1b. Therefore, an address signal for information management is formatted in the grooves 1a ... By modulating the wobbling frequency when the optical disc 1 is molded, and the land 1 is also formed.
Address signals for information management are formatted in b ... by forming pits 1c ... When the optical disc 1 is molded.

That is, the groove 1a of the optical disc 1 ...
When the laser beam is irradiated, the wobbling signal having the address information of the groove 1a uses the differential signal of the output of the light receiving section 7 described later, and the land 1b of the optical disc 1 ...
When the laser beam is irradiated, the pit signal having the address information of the land 1b uses the sum motion signal of the output of the light receiving section 7 to detect the address signal recorded in the groove 1a ... And the land 1b. Has become.

Further, in the above optical disk 1, when the light spot formed by the optical head 14 described later traces the grooves 1a ... Or the lands 1b .. In any case, the peripheral portion of the grooves 1a. Since it is illuminated by the spot, the wobbling frequency can always be detected. Therefore, by detecting the tracking error signal based on this wobbling frequency, it is possible to control the rotation of the spindle motor 13 (FIG. 5) as the drive means for rotationally driving the optical disc 1.

Since the pits 1c are formed only on the lands 1b ... In the optical disk 1, the pits 1c are formed as in the conventional case where pits are formed on both the grooves 1a and the lands 1b. 2 types of depths are not required, and only one type of pit 1c depth is required. As a result, the structure for forming the pits 1c in the manufacturing process can be simplified, and as a result, the manufacturing cost of the optical disc 1 can be reduced.

Further, the depth of the pits 1c ... Formed on the lands 1b of the optical disc 1 can be formed so as to match the depth of the grooves 1a ... As shown in FIG. 2 (b). . Therefore, when the optical disc 1 is molded in this manner, the manufacturing process can be further simplified, and the manufacturing cost of the optical disc 1 can be further reduced.

In order to accurately detect the pre-formatted address signal on the optical disc 1, the optical disc 1
When the wavelength of the light source that is irradiated onto the light source is λ, the depths of the grooves 1a ... And the pits 1c are λ / 10 to λ /
The groove 1a is preferably formed with a wobble amplitude of λ / 40 to λ / 7.

Further, at the time of molding the optical disk 1, the address signals are formatted by wobbling in the grooves 1a ... And the pits 1c in the lands 1b.
Since the address signal is formatted by ..., when formatting the address signal to both the groove 1a and the land 1b, it is not necessary to perform the initial formatting in the optical recording / reproducing apparatus after molding the optical disk like soft formatting. As a result, it is not necessary to provide the device with a mechanism for formatting in advance, and the reference signal used for controlling the rotation of the spindle motor 13 (FIG. 5) of the optical disc at the time of formatting is not required.
As a result, the optical recording / reproducing device for recording / reproducing information using the optical disc 1 having the above-described structure has a simple structure, and the size and cost of the device can be reduced.

Further, since the address signal is formed by wobbling in the groove 1a and the address signal is formed by the pit 1c in the land 1b, when the land 1b is traced, the pit is formed in the adjacent track, that is, the groove 1a. 1c does not exist. by this,
The address signal recorded on the optical disc 1 is not affected by the adjacent tracks. Therefore, no offset occurs in the tracking error signal, and an accurate tracking error signal can be obtained. Therefore, tracking servo can be performed accurately, and information can be accurately recorded / reproduced on / from the optical disc 1.

Further, in the magneto-optical disc device as an example of the optical recording / reproducing device for recording / reproducing information on / from the optical disc 1 having the above-mentioned structure, as shown in FIG. 3, the magneto-optical disc device serves as a light source for irradiating the optical disc 1 with laser light. An optical head 14 having a semiconductor laser 2 and a light receiving section 7 as a light receiving means for receiving the reflected light from the optical disk 1 is provided.

On the optical path from the semiconductor laser 2 to the optical disc 1 as a recording medium, a collimator lens 3, a polarizer 4, an optical branching element 5, in order from the semiconductor laser 2 side.
The objective lens 6 is arranged. That is, the semiconductor laser 2
The laser light emitted from the laser light is incident on the collimator lens 3 while being diffused, and is converted into parallel light. Further, the laser light passes through the light branching element 5, is condensed by the objective lens 6, and forms a light spot A on the optical disc 1. Then, the recording on the optical disc 1 is read by the reflected light from the light spot A.

The reflected light from the light spot A (hereinafter referred to as return light) is converted into parallel light by the objective lens 6 while being diffused again, and is incident on the light branching element 5 and reflected. An analyzer 8 is arranged on the optical path of the return light reflected by the light branching element 5 so that it can enter the light receiving portion 7.

The light receiving unit 7 is composed of, for example, a phototransistor, and converts a signal recorded on the optical disc 1, a light modulation signal by wobbling for address management or a light modulation signal by pits into an electric signal. Has become. This makes it possible to manage the address information recorded in the grooves and lands of the optical disc by a simple method. As a result, the structure of the optical recording / reproducing device can be simplified, and the size and cost of the device can be reduced.

Further, the light receiving area of the light receiving section 7 is shown in FIG.
As shown in FIG. 2, the optical disc 1 is divided into two by a dividing line g parallel to the track, and the first light receiving element 7a and the second light receiving element 7b are arranged in each region.
The second light receiving elements 7a and 7b can receive the incident light B from the optical disc 1 for each area. That is, the return light incident on the light receiving portion 7 is light divided into two by the above dividing line g, is incident on each of the light receiving elements 7a and 7b, and is converted into an electric signal. This electric signal is input to each amplifier described later, converted into an electric signal of a predetermined format, and input to the control device 12 as the control means shown in FIG.

The first light receiving element 7a of the light receiving unit 7 is connected in parallel to the non-inverting input terminal of the first differential amplifier 9, the non-inverting input terminal of the summing amplifier 10, and the non-inverting input terminal of the second differential amplifier 11. The second light receiving element 7b is connected to the inverting input terminal of the first differential amplifier 9, the non-inverting input terminal of the summing amplifier 10,
It is connected in parallel to the inverting input terminal of the second differential amplifier 11.

Therefore, in the first differential amplifier 9, the first differential amplifier 9
A differential signal is calculated from the electric signal from the light receiving portion 7a and the electric signal from the second light receiving portion 7b, and this differential signal is output to the control device 12 as a rotation control signal Sa for the spindle motor. In addition, the summing amplifier 10 calculates a sum signal from the electric signal from the first light receiving portion 7a and the electric signal from the second light receiving portion 7b, and calculates the sum signal as the address signal S of the land 1b.
It is output to the control device 12 as b. Further, in the second differential amplifier 11, a differential signal is calculated from the electrical signal from the first light receiving portion 7a and the electrical signal from the second light receiving portion 7b, and this differential signal is used as the address signal Sc of the groove 1a. Output to the control device 12.

Therefore, as shown in FIG. 5, the controller 12 controls the spindle motor rotation control signal Sa.
Is input, the rotation of the spindle motor 13 is controlled, and when the address signals Sb and Sc are input, the optical head 14 is drive-controlled to move to a predetermined recording or reproducing position on the optical disc 1. , And controls to record or reproduce information.

At this time, the control device 12 uses the sum signal from the summing amplifier 10 as an address signal when the light spot traces the land 1b, and when the light spot traces the groove 1a, The differential signal from the second differential amplifier 11 is discriminated as an address signal, and the address information of the optical disc 1 is managed.

The optical head 14 shown in FIG. 3 is an optical head for a magneto-optical disk utilizing the magneto-optical effect, but an optical disk according to the present invention can be used for a recordable disk by another method. The optical recording / reproducing apparatus is applicable.

Further, in the recording / reproducing apparatus shown in FIGS. 3 to 5, although not shown in the figure, reproduction of a signal recorded on an optical disk and generation and processing functions of a servo signal are added to the apparatus. Needless to say

According to the above configuration, when tracing the groove 1a of the optical disk 1, the first and second light receiving portions 7 of the light receiving portion 7 are traced.
The differential signal of the electric signals from the light receiving elements 7a and 7b is detected as an address signal, and the land 1b of the optical disc 1 is detected.
At the time of tracing, since the sum signal of the electric signals from the first and second light receiving portions 7a and 7b of the light receiving element 7 is detected as the address signal, it is necessary to clearly detect the address signal between the groove 1a and the land 1b. As a result, crosstalk between address signals of adjacent tracks can be reduced. Therefore, it is possible to accurately record and reproduce information on the optical disc 1.

Further, the control device 12 uses the optical disc 1 described above.
At the time of recording / reproducing information to / from the groove 1, the address information recorded in the groove 1a by the light modulation signal by wobbling is managed in the groove 1a, and in the land 1b, it is recorded in the land 1b by the light modulation signal by the pit 1c. Since the address information is managed, the address information recorded on the groove 1a and the land 1b of the optical disc 1 can be detected by a simple method. As a result, the structure of the device can be simplified, and the size and cost of the device can be reduced.

Further, since the spindle motor 13 is controlled on the basis of the wobbling frequency information, when the information is recorded / reproduced on / from both the groove 1a and the land 1b of the optical disc 1, the spindle motor 13 is accurately controlled. 13 can be controlled. by this,
Since the optical disc 1 can be stably rotated with a simple structure, it is possible to reduce the size and cost of the device.

Further, when tracing the land 1b of the optical disk 1, the wobbling frequency of the adjacent groove can be detected. As a result, this wobbling frequency can be applied to the rotation control of the spindle motor 12, so that the CLV control of the optical disc 1 can be easily performed for both the groove 1a and the land 1c.

In the present embodiment, the CLV system is adopted as the recording format of the optical disc 1, but the recording format is not limited to this, and other recording format system may be used, for example, CAV (Constant Angular Velocity: constant angular velocity). It is also possible to adopt the method). In this case, since the rotation speed of the spindle motor can be kept constant, the circuit of the device can be simplified and the spindle motor can be downsized.

Further, in the present embodiment, the light receiving section 7 is divided into two parts, but the present invention is not limited to this, and it is sufficient if it is two or more parts.

[0049]

As described above, the optical disk according to the first aspect of the present invention is an optical disk in which information is recorded and reproduced on both the groove and the land forming the track for guiding the light beam from the light source. The groove is formed by wobbling to record address information when the optical disc is molded, and the land is provided with pits.

As a result, there is no need to provide the device with a mechanism for formatting in advance, and there is no need for the reference signal used for controlling the rotation of the spindle motor as the drive means of the optical disc at the time of formatting. The optical recording / reproducing device for recording / reproducing information by using the optical disc of 1 has a simple structure, and the size and cost of the device can be reduced.

In the groove, the address signal is formed by wobbling, and in the land, the address signal is formed by the pit. Therefore, when the land is traced, there is no pit in the adjacent track, that is, the groove. Therefore, the intensity of the address signal does not change depending on the adjacent tracks, and an accurate tracking error signal can be obtained. Therefore, the tracking error signal does not have an offset, and the recording / reproducing of the optical disc can be performed accurately. There is an effect that can be.

The optical recording / reproducing apparatus according to the second aspect of the present invention is, as described above, an optical head for recording / reproducing information on / from both the groove and the land of the optical disc according to the first aspect, and the optical disc. At the time of recording / reproducing the information recorded on the optical disc, the disc driving means for rotating the optical disc drives the groove to manage the address information recorded in the groove by the modulation signal of the light by the wobbling, and at the land, the optical information by the pit. In addition to managing the address information recorded on the lands by the modulated signal, the control means controls the disk drive means on the basis of the wobbling frequency information.

As a result, the address information recorded in the grooves and lands of the optical disk can be managed by a simple method, and the optical disk can be stably rotated with a simple structure.

As a result, it is possible to reduce the size and cost of the device.

Further, as described above, the optical recording / reproducing apparatus according to the third aspect of the present invention is the optical recording / reproducing apparatus according to the second aspect, wherein the optical head receives the reflected light from the optical disk and outputs an electric signal. A light receiving means for converting into a light receiving means is provided, and the light receiving means has a light receiving area divided into at least two divisions in the direction parallel to the track of the optical disc, and when the information is recorded / reproduced on / from the groove of the optical disc, the two divisions are made. Detects the differential signal of the electrical signal from the light receiving area,
Further, at the time of recording / reproducing information to / from the land, the address information recorded on the optical disc is determined by detecting the sum signal of the electric signals from the light receiving area divided into two.

As a result, the groove and land address signals can be clearly distinguished and detected.
Crosstalk between address signals of adjacent tracks can be eliminated. Further, since the address signal of the optical disk can be stably reproduced by a simple method, information recording / reproduction can be accurately performed without requiring a complicated mechanism.

As a result, it is possible to reduce the size and cost of the device.

[Brief description of drawings]

FIG. 1 is a plan view of a track formed on an optical disc according to an embodiment of the present invention.

2A and 2B are cross-sectional views of the track of the optical disk shown in FIG. 1, in which FIG. 2A is a sectional view taken along the line aa, and FIG. 2B is a sectional view taken along the line bb. It is a figure.

FIG. 3 is a schematic configuration diagram of an optical disc device that records and reproduces information on the optical disc shown in FIG.

FIG. 4 is an explanatory diagram illustrating a light receiving element of the optical disk device shown in FIG. 3 and signal processing of the light receiving element.

5 is a control block diagram of the optical disc device shown in FIG. 3. FIG.

FIG. 6 is a plan view of a track formed on a conventional optical disc.

7A and 7B are cross-sectional views of the track of the optical disc shown in FIG. 6, in which FIG. 7A is a sectional view taken along the line aa, and FIG. 7B is a sectional view taken along the line bb. It is a figure, the same figure (c) is a cc line arrow sectional view, and the same figure (d) is d-.
It is a d line arrow sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 optical disk 1a groove 1b land 1c pit 2 semiconductor laser (light source) 7 light receiving portion (light receiving means) 7a first light receiving element (light receiving area) 7b second light receiving element (light receiving area) 12 control device (control means) 13 spindle motor ( Disk drive means) 14 Optical head

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G11B 27/10 A 8224-5D (72) Inventor Tomoyuki Miyake 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture No. 22, 22 Inventor Nobuo Ogata, 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture In the company

Claims (3)

[Claims] 1. An optical disc in which information is recorded / reproduced with respect to both a groove and a land forming a track for guiding a light beam from a light source, in order to record address information when molding the optical disc, The optical disc is characterized in that the groove is formed by wobbling and pits are formed in the land. 2. An optical head for recording / reproducing information on / from both the groove and the land of the optical disc according to claim 1, a disc driving means for rotationally driving the optical disc, and a recording of information recorded on the optical disc. During reproduction, the groove manages the address information recorded in the groove by the light modulation signal by wobbling, and the land manages the address information recorded in the land by the light modulation signal by the pits and
An optical recording / reproducing apparatus characterized in that both the land and the control means for controlling the disk drive means based on the wobbling frequency information are provided. 3. The optical head is provided with a light receiving means for receiving the reflected light from the optical disk and converting it into an electric signal, and the light receiving means is divided into at least two parts in a direction parallel to the track of the optical disk. It has a light receiving area and detects a differential signal of an electric signal from the divided light receiving area at the time of recording / reproducing information to / from the groove of the optical disc, and at the time of recording / reproducing information to / from the land, it is divided into two. 3. The optical recording / reproducing apparatus according to claim 2, wherein the address information recorded on the optical disc is discriminated by detecting a sum signal of electric signals from the light receiving area.