JPH0793766A - Device for reproducing optical information and information recording medium - Google Patents

Abstract

PURPOSE:To provide an information reproducing device and an information recording medium capable of continuously reproducing the information continuously recorded on first and second recording surfaces. CONSTITUTION:The addresses of 1-n are imparted to an A surface of an optical disk 1 from an inner periphery to an outer periphery, and the addresses of n+1 to 2n are imparted to the B surface from the outer periphery to the inner periphery. By head means 10 and 20 respectively opposed to the A surface and the B surface, the recorded information is read out continuously. In such a case, while the information is read out by the head means 10 opposed to the A surface successively from an address 1, the head means 20 is stood-by on the track of address n+1 of the B surface, and when the information on the A surface is read out to the track of address (n), continuously, the information on the B surface is read out successively from the track of address n+1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus capable of recording / reproducing continuous image information on both sides of a recording medium having first and second recording surfaces.

[0002]

2. Description of the Related Art A video disc is one in which a moving image is recorded on a disc-shaped recording medium.

In this type of video disc, moving images (image information) are recorded on the first recording surface and the second recording surface independently or continuously.

When the information recorded on the first surface and the opposite second surface is continuously reproduced, the rotation of the video disk is once stopped when the reproduction of the image on the first surface is completed. After being stopped, the video disc is rotated in the reverse direction. During this time, the reproducing head is moved from the first surface to the second surface,
When the rotation of the disk reaches a predetermined number of rotations, the reproducing head accesses a predetermined position on the second surface and the image on the second surface is reproduced.

It is also known that a reproducing head is arranged to face each of the first and second recording surfaces.

[0006]

In the above video disc, it is desired that the images recorded on both sides of the disc can be continuously reproduced.

However, in the conventional method, the reproducing head must be moved from the first surface to the second surface to position the reproducing head at a predetermined position, and the disc should be rotated in the opposite direction. Due to the fact that it must be done, there is a problem that it takes, for example, ten and several seconds before the image on the second surface following the first surface is reproduced.

[0008] For example, when the information recorded on the disc is a movie, not only the reproduction of the moving image is interrupted but also the user is entertained. If the information recorded on the disc is continuous written information, the information recorded on the second surface is not removed even though the adjacent (continuous) pages are read. There is a problem that the time is increased several times to ten times as much as that of taking out the information recorded on the same surface.

Even when the reproducing head is arranged on each of the first and second surfaces, the reproduced image is interrupted by the time required to reverse the rotation of the video disc. Inevitable.

An object of the present invention is to provide an information reproducing apparatus and an information recording medium capable of continuously reproducing information recorded continuously on the first and second recording surfaces.

[0011]

The present invention has been made on the basis of the above problems, and includes a first recording surface and a second recording surface opposed to the first recording surface via a base material. A first head means facing the first recording surface of the recording medium having a second head means facing the second recording surface of the recording medium, and the recording medium at a predetermined speed. Rotation driving means for rotating the recording medium and one of the first and second head means for reading the information recorded on the recording medium, the innermost circumference of the recording surface facing each other. Then, the reading of the information is started, and the other one of the first and second head means is positioned at the outermost circumference of the recording surface which is opposed and is positioned at the innermost circumference. When the information read by the head means is finished, the outermost Successively by the head means that is located there is provided an optical information reproducing apparatus and a control means for controlling so as to read the information on the remaining recording surfaces.

Further, according to the present invention, the address formed by spiraling from the inner circumference to the outer circumference, the address indicated by 1 at the innermost circumference and the address indicated by n at the outermost circumference,
A first recording surface having guide grooves that respectively include it, is opposed to this first recording surface via a base material, is formed in a spiral shape from the inner circumference to the outer circumference, and is indicated by 2n at the innermost circumference. A first head unit facing one of the recording surfaces of a recording medium having a second recording surface having a guide groove including an address and an address indicated by n + 1 at the outermost peripheral portion; The second head unit facing the remaining recording surface of the recording medium and the recording medium are defined according to the position of the guide groove of the recording surface where the first and second head units face each other. When the rotational driving means for rotating at a speed and the recording surface of the recording medium facing the first head means have an address indicated by 1 in the innermost peripheral portion, the first head means is opposed. While being positioned on the innermost circumference of the recording surface While rotating the rotation driving means in the first direction, the second head means is positioned at the outermost circumference of the recording surface facing the recording head, and the first head means records on the recording surface facing the recording head. Information is sequentially read from the innermost circumference to the outermost circumference, and when the first head means reaches the facing recording surface, the second head is continuously read by the first head means. The information recorded on the facing recording surfaces is read from the outermost circumference toward the innermost circumference by the head means of
When the recording surface of the recording medium facing the first head means has an address indicated by 2n in the innermost peripheral portion, the second head means is disposed in the innermost circumference of the recording surface facing the second head means. On the other hand, while the rotational drive means is rotated in the second direction opposite to the first direction while being positioned, the first head means is positioned at the outermost circumference of the recording surface facing the second head. The information recorded on the facing recording surface is sequentially read by the means from the innermost circumference to the outermost circumference, and then the second head means reaches the facing recording surface when the second head means reaches the facing recording surface. Following the reading by the second head means, the information recorded on the facing recording surface is read by the first head means from the outermost circumference to the innermost circumference, and the speed of the rotation driving means is changed. The first head means described above An optical information reproducing apparatus having a control means for controlling the reading speed is gradually increased when the information is read by the second head means, and is gradually increased when the information is read by the second head means. To be done.

Further, according to the present invention, the spirally formed from the inner circumference toward the outer circumference, the address indicated by 1 at the innermost peripheral portion and the address indicated by n at the outermost peripheral portion are provided. A first recording surface having guide grooves that respectively include it, is opposed to this first recording surface via a base material, is formed in a spiral shape from the inner circumference to the outer circumference, and is indicated by 2n at the innermost circumference. A second recording surface having guide grooves each containing an address and an address indicated by n + 1 at the outermost peripheral portion;
An information recording medium having the following is provided.

[0014]

According to the information reproducing apparatus of the present invention, the first recording surface is provided with addresses 1 to n from the inner circumference toward the outer circumference, and the first recording surface is opposed to the first recording surface and extends from the outer circumference toward the inner circumference. And a second recording surface to which addresses n + 1 to 2n are assigned, the first and second head means arranged to face the respective recording surfaces of the recording medium are opposed to the first recording surface. While the head means reads information sequentially from the address indicated by 1, the remaining head means waits in the guide groove provided with the address indicated by n + 1, and the head means opposed to the first recording surface is indicated by n. When the guide groove of the address shown is reached, the head means facing the second recording surface continuously reads the information of the guide groove of the address n + 1.

Therefore, the information recorded on the first and second recording surfaces is continuously reproduced without interruption.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic structure of the disk device of the present invention, FIG. 2 shows an information recording medium suitable for the disk device shown in FIG. 1, and FIG. Cartridges containing the indicated information recording media are shown, respectively.

According to FIG. 1, a recording medium having a first recording surface A (hereinafter referred to as A surface) and a second recording surface B (hereinafter referred to as B surface), that is, an optical disk 1, is capable of reversing the rotation direction. It is rotated at a predetermined speed via another driving means, that is, the spindle motor 2. The spindle motor 2 has a motor control circuit 3
Thus, the linear velocity of the track spirally formed on the recording surface of the optical disc 1 is rotated so as to be constant with respect to the reproducing head described later. The motor control circuit 3 is composed of a well-known PLL circuit, and rotates the spindle motor 2 at a rotation speed synchronized with the output pulse b from the variable frequency divider 4. In this case, the frequency and phase of the pulse a corresponding to the rotation speed of the spindle motor 2 are compared with the output pulse b from the variable frequency divider 4 to provide an accurate rotation speed.
The input of the variable frequency divider 4 is supplied from the crystal oscillator 5.

The variable frequency divider 4 of the crystal oscillator 5 responds to the position signal corresponding to the address position of the optical disk 1 output from the control circuit 9 composed of CPU so as to keep the linear velocity of the track constant. The output is divided and output to the motor control circuit 3. The variable frequency divider 4 is composed of a counter, for example, and divides the output of the crystal oscillator 5 by inputting the frequency division ratio of the counter from the control circuit 9. Further, the rotation direction of the spindle motor 2 is instructed to the motor control circuit 3 based on the rotation direction switching signal c from the control circuit 9 corresponding to the insertion direction of the disk 1 input by the signal processing circuit 8.

In this embodiment, since the data recorded on the disc 1 is intended for recording or reproducing a digitized moving image, when the digitally modulated image is demodulated, this digital modulation code is used. Since there is no problem as long as it is sufficiently smaller than the decoding limit, the change of the rotation speed according to the address position is set to 1% or less. In this way, the spindle motor 2 is operated at a modified and substantially constant linear velocity.

The first and second optical heads 10 and 20 are independently movable with respect to both surfaces A and B of the optical disk 1, and further, information can be reproduced and recorded independently. It is located in.

The optical head 10 is arranged on the side of the spindle motor 2 and is mounted on the linear motor 19 so as to be movable in the radial direction of the optical disc 1 along the surface A of the optical disc 1. There is.

The laser beam from the semiconductor laser 11 is collimated by the collimator lens 12, passes through the polarization beam splitter 13, and is converged by the objective lens 14.
A minute spot is provided at a predetermined position on the A surface of the. That is, the objective lens 14 is moved in a direction orthogonal to the A surface of the disk 1 and in a direction traversing the tracks of the A surface by a two-dimensional actuator that can be displaced vertically and horizontally, that is, a focusing actuator 15 and a tracking actuator 16. A laser beam for recording or reproducing is recorded on the surface A of the optical disc 1.

The reflected light from the disk A surface of the optical disk 1 passes through the objective lens 14 of the optical head 10, is reflected by the polarization beam splitter 13, is condensed through the compound lens 17, and is input to the detector 18. . The detector 18 has a plurality of detection areas (not shown) given a predetermined number and area, and detects focus position deviation, track position deviation,
And an information reproduction signal is obtained.

The signals from the detector 18 are the focus servo circuit 34, the tracking servo circuit 35, and
It is input to the signal processing circuit 39.

In the focus servo circuit 34 and the tracking servo circuit 35, the two-dimensional actuators 15 and 16 are operated based on the focus position shift signal and the track position shift signal.
The amount of control to be supplied to is defined, and accurate focusing and tracking are maintained. Since focusing and tracking are well known, detailed description thereof will be omitted.

Similarly, the second optical head 20 disposed on the B surface of the optical disk 1 is formed so as to be movable in the radial direction of the optical disk 1 along the B surface of the optical disk 1 via the linear motor 29. Has been done.

The laser beam from the semiconductor laser 21 of the second optical head 20 is collimated by the collimator lens 22, passes through the polarization beam splitter 23, is focused by the objective lens 24, and is directed to the B surface of the optical disc 1. A minute spot is provided at a predetermined position. That is, the objective lens 24 is moved by the two-dimensional actuators 25 and 26, which can be vertically and horizontally displaced, in a direction orthogonal to the B surface of the disk 1 and in a direction traversing the tracks of the B surface to record or reproduce moving image information. The laser beam from the laser 21 for projection is projected on the B surface of the optical disc 1.

The reflected light from the disc B surface of the optical disc 1 passes through the objective lens 24, is reflected by the polarization beam splitter 23, is condensed through the compound lens 27, and is input to the detector 28. The detector 28, like the detector 18 arranged on the surface A of the disk 1, has a predetermined number and area.
It has a plurality of detection areas (not shown), and is configured to obtain focus position shift detection, track position shift detection, and information reproduction signals. The signals from the detector 28 are input to the focus servo circuit 33, the tracking servo circuit 32, and the signal processing circuit 38, respectively.

In the focus servo circuit 33 and the tracking servo circuit 32, like the optical head 10 facing the surface A, the two-dimensional actuators 25 and 26 should be supplied based on the focus position shift signal and the track position shift signal. A controlled variable is defined to maintain accurate focusing and tracking.

According to FIG. 2, the optical disc 1 has a first spiral track formed from the center toward the outer periphery.
Recording surface, that is, the A surface, and the second recording surface, which is given the same rotation direction as the A surface and has one spiral track formed from the center toward the outer periphery, like the A surface. And a face. Here, as shown in FIG.
Addresses "1" to "n" are given as shown in (a), and addresses "n + 1" to "2n" are given to the B side as shown in FIG. 2 (B). Has been given.

The address "n" on the surface A and the address "n + 1" on the surface B are formed at substantially the same position (distance from the center of the disk) in the radial direction of the disk 1. In addition, the optical disc 1 is mounted on the first surface and the second
By treating both sides of one side as substantially one recording area, the control data area of one side is simplified, so that the recording capacity can be increased.

According to FIG. 3, the disk cartridge 50
Is the first head 10 in the insertion direction, that is, which of the A side and the B side.
It has a notch 50a used for distinguishing whether it is inserted so as to be opposed to. The notch 50a of the cartridge 50 is a position attached to the spindle motor 2,
The presence / absence of the cutout 50a is detected by the detection means including the light emitting diode 6 and the photo sensor 7. By supplying the output from the detection means to the processing circuit 8, the notch
"1" or "0" corresponding to the presence or absence of 50a is the control circuit 9
Entered in.

The operation of the disk device shown in FIG. 1 will be described in detail with reference to FIG.

When the disc cartridge 50 is inserted, the control circuit 9 sets A based on the detection result input from the signal processing circuit 8, that is, "1" or "0" indicating the insertion direction of the cartridge 50. The motor control circuit 3 is discriminated by the rotation direction switching signal c of the spindle motor 2 on the basis of the rotation direction data stored in the ROM (not shown). The rotation direction is output with respect to.

When the output of the processing circuit 8 is, for example, "1" and the A side of the disk 1 faces the first head 10, the control circuit 9 outputs the rotation direction switching signal c as For example, “1” is input to the motor control circuit 3.
In this case, the optical disc 1 is rotated counterclockwise as viewed from the A surface. Generally, the first head 10 is moved from the center of the disc 1 toward the outer periphery, so that information is sequentially reproduced from address 1 to address n on the A side of the optical disc 1.

On the contrary, the output of the processing circuit 8 is, for example,
When the surface B of the disk 1 is "0" and the first head 10 is opposed to the first head 10, the control circuit 9 inputs, for example, "0" to the motor control circuit 3 as the rotation direction switching signal c. To be done. In this case, the optical disc 1 is rotated clockwise as viewed from the B side. At the same time, A of optical disc 1
The second head 20 facing the surface is moved toward address 1 of the innermost track on the A surface.

Hereinafter, the side A of the optical disk 1 is the first head.
The state of facing 10 will be described.

When the optical disc 1 is inserted as shown in FIG. 1, the linear motor control circuit 36 is energized and the linear motor 19 is operated by the control of the control circuit 9 to operate the first optical head. 10 is moved toward the innermost track of the A-side track of the disk 1. At the same time, the laser 11 of the first optical head 10 is controlled by the control circuit 9.
Is driven via the laser drive circuit 37, and the objective lens 14 of the optical head 10 is focused and tracked by the laser beam from the laser 11 to the innermost track of the A surface, and the optical head 10 is set to the address "1". It is accessed and positioned. Similarly, the second optical head 20 is accessed and positioned at the address "n + 1" of the outermost track on the B side by the operation of the linear motor 29 under the control of the linear motor control circuit 31. The first
Laser drive circuit 37 for energizing the laser 11 of the optical head 10
An output switching device 41 is arranged between the laser drive circuit 30 and the laser drive circuit 30 for energizing the laser 21 of the second optical head 20. When not operating, the laser beam output is stopped.

Further, the control circuit 9 outputs the rotation direction switching signal c indicated by "1" to the motor control circuit 3 and the variable frequency divider 4 outputs a predetermined rotation corresponding to the address "1". The division ratio, which is a number, is input, and the disk 1
However, the disc 1 is rotated counterclockwise when viewed from the A side.

In this manner, the focusing and tracking of the optical head 10 traces the track on the A side, and the image is sequentially reproduced from the address "1".
As described above, the A side of the disc 1 has a structure shown in FIG.
As shown in (a), since the addresses “1” to “n” are given from the inner circumference to the outer circumference, the first optical head 10 passes through the linear motor 19 and
Along the track, it is moved radially in sequence.

As is well known, the length of each track of the disk 1 increases as it goes to the outer circumference, so that the spindle motor 2 is controlled by the motor control circuit 3 to rotate at a different speed. Is gradually lowered. That is, by counting up the address data, the speed signal output from the control circuit 9 is reduced, and the frequency division ratio of the oscillator 5 by the variable frequency divider 4 is changed according to the speed signal. The rotation of the spindle motor 2 is reduced.

When the track on the surface A of the optical disc 1 is traced, the tracking actuator 16 of the two-dimensional actuator is displaced due to the DC component of the residual error of the tracking position deviation signal. From this, the DC component is input to the linear motor control circuit 36 by the well-known double-loop tracking, and the tracking actuator 17 and the linear motor 19 continuously perform the first operation from the address "1" to the address "n". It goes without saying that the optical head 10 can accurately trace the A-side track.

The reproduced signal extracted by the first head 10 passes through the signal processing circuit 39 and the interface circuit 40.
Is output to the outside and displayed via a display device (not shown). A changeover switch 42 is arranged between the signal processing circuit 39 and the interface circuit 40, and the output from the signal processing circuit 38 to which the reproduction signal from the second head 20 is input is switched as necessary. .

While the information on the surface A is being reproduced by the first optical head 10, when the address read via the first optical head 10 reaches, for example, "nx". In response to an instruction from the control circuit 9, the laser control circuit 30 of the second optical head 20 facing the surface B is turned on,
A laser beam is generated from the scanner 21 and the reading of the information at the address "n + 1" on the B side is prepared. That is, when the A side is discriminated, the second head 20 positioned at the address "n + 1" of the B side is defined in the image reproducing state. Incidentally, “x” in the address “n−x” is the head
It is predetermined based on 20 moving speeds, average focusing time, average tracking time, and the like.

Subsequently, when the information (image) on the A side is reproduced through the first head 10 and the address "n" of the outermost track is read, the changeover switch shown in FIG. 42 is switched, and the address "n +" of the B side following the A side of the disk 1 is passed through the second optical head 20.
The data of "1" is read. Therefore, the changeover switch
Only with a short switching time by 42, the information on the B side is continuously reproduced following the A side.

As described above, the B of the disc 1 is
The surface is given an address designated to increase from the outer circumference to the inner circumference. Therefore, in the spindle motor 2, when the surface being reproduced is the B surface, the frequency division ratio of the frequency of the oscillator 5 by the variable frequency divider 4 is changed by counting up the address data, The rotation of the motor 2 is gradually increased. That is, when the addresses "n + 1" to "2n" are reproduced, the number of revolutions of the spindle motor 2 is gradually increased corresponding to the address value in response to the address increase.

This indicates that the speed at which the disc 1 is rotated can be the same when the reproducing surface is switched from the A surface to the B surface. Therefore, as described above, the changeover switch 42 causes the first and second heads 10 and 20 to move.
By switching the signal processing circuit to which the output from is supplied, the information on the B side can be continuously reproduced after the A side.

Next, the B side of the optical disk 1 is the first head.
The state of facing 10 will be described.

When the output from the signal processing circuit 8 indicates that the B side of the optical disk 1 is opposed to the first head 10, the control circuit 9 controls the motor control circuit 3 to display " The rotation direction switching signal c indicated by "0" is output, and the address "n + 1" is output to the variable frequency divider 4.
Is input, and the disk 1 is rotated clockwise when the disk 1 is viewed from the B surface.

Subsequently, the linear motor control circuit 31 is energized, the linear motor 29 is operated, and the second optical head 20 is activated.
Are moved toward the outermost track of the tracks on the B side of the disk 1. At the same time, by the control of the control circuit 9,
The laser 21 of the second optical head 20 is energized via the laser driving circuit 30, and the laser beam from this laser 21 causes the objective lens 24 of the optical head 20 to be focused and tracked to the outermost track of the B surface, and Head 20
Is positioned by accessing the address "n + 1". Similarly, the first optical head 10 is positioned and accessed by the address "1" at the innermost circumference of the surface A by the operation of the linear motor 19 under the control of the linear motor control circuit 36.

In this way, the track on the surface A is traced by the focusing and tracking of the second optical head 20 this time, and the image is reproduced sequentially from the address "1". Needless to say, the second optical head 20
Are sequentially moved in the radial direction of the disk 1 along the track from the addresses "1" to "n" via the linear motor 29.

The reproduction signal taken out by the second head 20 is output to the outside through the signal processing circuit 39 and the changeover switch 42, the interface circuit 40, and is displayed via a display device (not shown).

Hereinafter, the side A which has already been described is the first head 10
In the same manner as in the case where the first head 10 reproduces the information on the A side of the disk 1 in the same manner as when the second head 20 is read, and the address "n" is read,
The data recorded on the surface is continuously reproduced.

In this way, moving image information is continuously reproduced from the address "1" to the address "2n" regardless of which direction the optical disc 1 is inserted.

Next, the operation during recording will be described with reference to FIG.

When the disk cartridge 50 is inserted, the control circuit 9 determines whether the surface facing the first head 10 is the A surface or the B surface based on the detection result input from the signal processing circuit 8. It is determined and the spindle motor 2 is rotated in a predetermined direction based on the rotation direction data stored in the ROM (not shown).

When the output of the processing circuit 8 is, for example, "1" and the A side of the disk 1 faces the first head 10, the control circuit 9 outputs the rotation direction switching signal c as For example, “1” is input to the motor control circuit 3.
In this case, the optical disc 1 is rotated counterclockwise as viewed from the A surface. Generally, the first head 10 is moved from the center of the disc 1 toward the outer periphery, so that information is sequentially reproduced from address 1 to address n on the A side of the optical disc 1.

On the contrary, the output of the processing circuit 8 is, for example,
When the surface B of the disk 1 is "0" and the first head 10 is opposed to the first head 10, the control circuit 9 inputs, for example, "0" to the motor control circuit 3 as the rotation direction switching signal c. To be done. In this case, the optical disc 1 is rotated clockwise as viewed from the B side. At the same time, A of optical disc 1
The second head 20 facing the surface is moved toward address 1 of the innermost track on the A surface.

When the optical disc 1 is inserted as shown in FIG. 1, the linear motor control circuit 36 is energized by the control of the control circuit 9 and the linear motor 19 is operated to operate the first optical disc. The head 10 is moved toward the innermost track of the tracks on the A side of the disk 1. At the same time, the laser 11 of the first optical head 10 is controlled by the control circuit 9.
Is driven via the laser drive circuit 37, and the objective lens 14 of the optical head 10 is focused and tracked by the laser beam from the laser 11 to the innermost track of the A surface, and the optical head 10 is set to the address "1". It is accessed and positioned. Similarly, the second optical head 20 is accessed and positioned at the address "n + 1" of the outermost track on the B side by the operation of the linear motor 29 under the control of the linear motor control circuit 31.

In this manner, the focusing and tracking of the first optical head 10 traces the track on the A side, which is output from the laser 11 based on the recording data stored in a storage device (not shown) such as a buffer memory. The intensity of the laser beam is changed, and images are sequentially recorded from the address "1". In this case, it goes without saying that the output from the laser 11, that is, the recording data supplied to the laser drive circuit 37 is supplied via the changeover switch 42.

As already described, the A side of the disk 1 is given addresses "1" to "n" from the inner circumference to the outer circumference, as shown in FIG. 2 (a). Therefore, the first optical head 10 is a linear motor.
It is moved radially along the track, via 19, in turn. In the spindle motor 2, as the optical head 10 is moved in the radial direction, the frequency division ratio of the oscillator 5 by the variable frequency divider 4 is changed as described above, and the radius of the head 10 is changed. The speed is gradually reduced according to the position in the direction.

While the information is recorded on the surface A by the first optical head 10, when the address read via the first optical head 10 reaches, for example, "nx". In response to an instruction from the control circuit 9, the laser control circuit 30 of the second optical head 20 facing the surface B is turned on,
A laser beam is generated from the scanner 21, and recording of information at the address "n + 1" on the B side is prepared. That is, when the A side is discriminated, the second head 20 positioned at the address "n + 1" of the B side is defined in the recording state.

Subsequently, when the information (image) is recorded on the surface A through the first head 10 and the address "n" of the outermost track is read, the changeover switch shown in FIG. 42 is switched, and the address "n +" of the B side following the A side of the disk 1 is passed through the second optical head 20.
Information is recorded in "1". Therefore, the information can be continuously recorded on the surface B and subsequently on the surface B with a short switching time by the changeover switch 42. In this case, spindle motor 2
As described above, the rotation of is gradually increased in response to the address increase.

Even when the A side and the B side of the disk 1 are inserted in reverse, information is recorded and extracted from the second head 20 in the same manner as the data reproduction described with reference to FIG. Subsequently, information is recorded by the first head 10.

[0066]

As described above, according to the present invention, the optical disk is 1 to n from the inner circumference toward the outer circumference.
The optical disc has an A side to which the address is given and a B side to which addresses from n + 1 to 2n are given from the outer circumference to the inner circumference. And by the second head means 10 and 20,
The recorded information is continuously read. In this case, while the head means facing the A side sequentially reads information from the address indicated by 1, the remaining head means waits on the track given the address indicated by n + 1 on the B side, and At the time when the information up to the track of the address indicated by n is read, the information on the side B is n + 1 continuously.
The tracks are read in order from the address track indicated by.

Therefore, the information recorded on both sides of the optical disc can be continuously reproduced without interruption, and when the information recorded on the disc is a movie, it is not interrupted in the middle. At the same time, even when the information of the adjacent pages is recorded on the A side and the B side, the time required for the search and the reading is greatly reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an optical disk device in which an embodiment of the present invention is incorporated.

FIG. 2 is a schematic plan view showing an example of tracks of an optical disc suitable for the optical disc device shown in FIG.

FIG. 3 is a plan view showing a cartridge that accommodates the optical disc shown in FIG.

4 is a flowchart showing an example of the operation of the optical disc device shown in FIG.

5 is a flowchart showing a modification of the operation shown in FIG.

[Explanation of symbols]

1 ... Optical disc, 2 ... Spindle motor, 3 ... Motor control circuit, 4 ... Variable frequency divider, 5 ... Crystal oscillator, 6 ... Light emitting diode, 7 ... Photosensor, 8 ... Signal processing circuit, 9 ...
Control circuit, 10 ... First optical head, 11 ... Semiconductor laser,
12 ... Collimator lens, 13 ... Polarizing beam splitter, 14
… Objective lens, 15… Focusing actuator, 16
… Tracking actuator, 17… Composite lens, 18…
Detector, 19 ... Linear motor, 20 ... Second optical head, 21
... semiconductor laser, 22 ... collimator lens, 23 ... polarization beam splitter, 24 ... objective lens, 25 ... focusing actuator, 26 ... tracking actuator, 27 ...
Compound lens, 28 ... Detector, 29 ... Linear motor, 30 ... Laser drive circuit, 31 ... Linear motor control circuit, 32 ... Tracking servo circuit, 33 ... Focus servo circuit, 34 ... Focus servo circuit, 35 ... Tracking servo circuit, 36 ...
Linear motor control circuit, 37 ... Laser drive circuit, 38 ... Signal processing circuit, 39 ... Signal processing circuit, 40 ... Interface circuit, 41 ... Output switching device, 42 ... Changeover switch, 50 ... Disk cartridge.

Claims (5)

[Claims] 1. A first recording medium having a first recording surface and a second recording surface opposed to the first recording surface via a base material, the first recording surface facing the first recording surface. Head means, second head means facing the second recording surface of the recording medium, rotation driving means for rotating the recording medium at a predetermined speed, and information recorded on the recording medium. At the time of reading, one of the first and second head means is positioned at the innermost circumference of the facing recording surface, and then reading of information is started. The other one of the head means is located at the outermost circumference of the recording surface facing the recording means, and is positioned at the outermost circumference when the information read by the head means located at the innermost circumference is completed. Information on the remaining recording surface continuously by the head means Optical information reproducing apparatus having a control means for controlling so as to read, the. 2. A first groove having a guide groove formed in a spiral shape from the inner circumference toward the outer circumference, the guide groove including an address indicated by 1 at the innermost circumference and an address indicated by n at the outermost circumference. One recording surface and the first recording surface are opposed to each other via the base material, and are formed in a spiral shape from the inner circumference to the outer circumference,
A recording medium having a second recording surface having a guide groove including an address indicated by 2n in the innermost peripheral portion and an address indicated by n + 1 in the outermost peripheral portion is opposed to either one of the recording surfaces. A first head means, a second head means facing the remaining recording surface of the recording medium, and a guide for the recording medium on the recording surface where the first and second head means face each other. In the case where the rotation driving means for rotating at a speed defined according to the position of the groove and the recording surface of the recording medium facing the first head means have an address indicated by 1 in the innermost peripheral portion, , While the first head means is positioned at the innermost circumference of the facing recording surface, the second head means is rotated in the first direction while the second head means is positioned on the facing recording surface. Located on the outermost periphery, the first head The information recorded on the facing recording surfaces by the steps is sequentially read from the innermost circumference toward the outermost circumference, and the first head means reaches the facing recording surface when the first head means reaches the facing recording surface. In succession to the reading by the head means, the information recorded on the facing recording surface is read by the second head means from the outermost circumference to the innermost circumference, and at the same time, by the first head means. When the recording surface of the recording medium which is opposed has an address indicated by 2n in the innermost peripheral portion, the second head means is positioned on the innermost peripheral portion of the recording surface which is opposed and the rotation is performed. While rotating the drive means in the second direction opposite to the first direction, the first head means is located at the outermost periphery of the recording surface to be opposed, and is opposed by the second head means. Recorded on the recording surface After sequentially reading the information from the innermost circumference to the outermost circumference, the first head is continuously read by the second head means when the second head means reaches the facing recording surface. Information recorded on the facing recording surface is read from the outermost circumference to the innermost circumference by the head means, and the speed of the rotary drive means is read by the first head means. In this case, gradually slower, and when information is being read by the second head means, gradually faster, control means for controlling,
An optical information reproducing device having a. 3. An optical information reproducing apparatus according to claim 2, further comprising insertion direction detecting means for detecting an orientation of a recording surface of said recording medium facing said first and second head means. . 4. A guide groove, which is formed in a spiral shape from the inner circumference toward the outer circumference and has a guide groove including an address indicated by 1 at the innermost circumference and an address indicated by n at the outermost circumference. One recording surface and the first recording surface are opposed to each other via the base material, and are formed in a spiral shape from the inner circumference to the outer circumference,
An information recording medium having a second recording surface having a guide groove including an address indicated by 2n in the innermost peripheral portion and an address indicated by n + 1 in the outermost peripheral portion. 5. A guide groove having an address indicated by n and n
5. The information recording medium according to claim 4, wherein the guide groove having an address indicated by +1 is arranged at a position where the distance in the radial direction is substantially the same.