JPH0440640A - Double-sided disk and its recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain correct recording and reproducing independently of the loading direction of a disk by allowing a spiral direction and the shape of tracks on the front surface of the disk to coincide with that of the rear face at the time of observing them from a recording and reproducing face and providing a face identification signal on a prescribed face. CONSTITUTION:The quantity of light received by a detector 3c based upon the mark of a face discriminating signal is changed in accordance with the rotation of the disk. The detector 3c outputs a regenerative signal proportional to the quantity of received light to a deciding circuit 11, which decides the face identification signal is based upon the A or B face from the change of the regenerative signal. In this case, the circuit 11 decides the A face when the change of the regenerative signal is once per rotation, or the B face in the case of twice and sends the decided result to a control circuit 6 as a face deciding signal. The control circuit 6 sets up the rotational direction of a spindle from the face deciding signal. Consequently, the disk can be rotated in the correct direction and an optical head can be accessed to the specified face.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a double-sided disc for continuously recording and reproducing information such as images on both sides of the disc, and a recording/reproducing apparatus therefor.

Conventional technology Optical video discs and audio discs have already been put into practical use and are rapidly becoming popular, forming a large market. In the consumer field, the majority of discs are playback-only discs, but as a result of advances in optical disc technology, discs that can directly record and play back signals and discs that can play both sides continuously are being developed.

Along with this, we are developing a recording/playback device that records and plays back digital signals, audio signals, video signals, etc., as well as a playback device that rotates a playback-only double-sided disk and reads signals continuously from both sides. It is being said.

As shown in FIGS. 7(a) and 7(b), optical discs such as conventional optical video discs and the like are available.

1b, signals are generally recorded from the inner circumference to the outer circumference of the disk. FIG. 7(a) shows one side A, and FIG. 7b) shows side B, which is the back side of side A.

This disc Ia and Ib are pasted together to form a double-sided disc I.
Create. That is, the spiral directions of the tracks as viewed from the recording (reproduction) surface of the disk are the same, and the rotational directions as viewed from the optical head 3 are as shown by Ig and Ih. As shown in FIG. 8, many conventional recording and reproducing apparatuses are capable of recording and reproducing information on only one side of a disc. Therefore, the rotation directions 1g and 1h of the spindle motor 2 are only one predetermined direction. Therefore, when recording and reproducing data on the back side of the disc 1, it is necessary to turn the disc over. Furthermore, the optical head 3 had to be moved to the inner circumference of the double-sided disk 1 and returned to its initial position.

Also, in Figure 9, (a) represents side A, and (b) represents side B.
A video disc player has also been developed which continuously reproduces both sides 1a and -1b of the disc 1 as shown in FIG. When playing the back side of a disc with this player,
The rotation direction of the spindle motor 2 is reversed as shown by rotation directions 1d and +e, and the optical heads 3a and 3b are moved from the outer circumference of the front surface to the inner circumference of the back surface, and then reproduction is performed toward the outer circumference. Components having similar functions from FIG. 7 to FIG. 12 will be described with the same reference numerals, or the optical head 3 or 3a.

A transfer drive circuit 4 for transferring the spindle motor 3b is controlled by a control circuit 6 together with a motor drive circuit 5 for driving the spindle motor 2.

For example, video discs such as movies have long playback times, so they are recorded on both sides of the disc. In order to play back both sides of such a video disc, the disc must be turned over midway through the apparatus shown in FIG. Furthermore, even in the double-sided playback player having the configuration shown in FIGS. 9 and 10, the rotation of the spindle motor 1 must be reversed, which increases the waiting time until the normal number of rotations is reached. In either case, it is difficult to reproduce both sides of the disc continuously without interruption.

Therefore, continuous recording is performed on both sides of the disc without interruption.
devised an optical disc that could be played back (Japanese Patent Application Laid-Open No.
-109571). As shown in FIGS. 11(a) and 11(b), in this disc, which has side A and side B, respectively, the spiral direction of the track as seen from the recording (playback) surface is the same on both sides, or the signal recording direction is is different on the front and back sides. When this disk l is rotated in a predetermined direction of rotation, for example, if the tracks on one side (referred to as side A) expand outward in the direction of rotation of 1g, the signal is sent from the inner circumference to the outer circumference. Record. The tracks on the other side (referred to as side B) contract inward as they rotate in the direction of Ih, so signals are recorded from the outer circumference toward the inner circumference. When playing side A to B continuously on this disc, the optical head 3a plays side A to the outermost circumference, moves it to the outermost circumference of side B, and from there moves the optical head toward the inner circumference. 3b continues playback. At this time, since there is no need to reverse the rotation of the spindle motor 2, waiting time can be shortened. It is also possible to perform complete continuous playback by having independent optical inputs 7h'3a and 3b on each side and having side 21 on side B stand by before the end of side A.

In this disk, since the rotational direction of the spindle motor 2 is constant, the rotational direction of the disk as viewed from each recording surface is reversed.

Problem to be Solved by the Invention However, in the disk 1 having the structure shown in FIG. 7 and the recording/reproducing apparatus shown in FIG. Ta. Therefore, in order to record or reproduce signals on both sides 1a and 1b of the disc 1, it is necessary to turn the disc 1 over, making continuous recording and reproduction on both sides impossible.

In addition, in a disk 1 having a configuration as shown in FIG. 9 and a recording/reproducing device as shown in FIG. 10, an optical head 3a corresponds to one side 1a of the disk 1, and an optical head 3b corresponds to the other side 1b. , since signals are recorded or reproduced, there is no need to turn over the disk l, or when moving from one side 1a to another side 1b, the optical heads 3a and 3b are moved in the inner circumferential direction of the disk l, and the spindle motor 2 is reversely operated. The signal must be recorded or reproduced again by rotation. As a result, interruptions occurred in the signal input to or output from the disk 1.

Further, in the disk 1 having the configuration shown in FIG. 11 and the recording/reproducing device shown in FIG. When moving to 1b (and vice versa), the signals of the optical heads 3a and 3b are switched while keeping the rotational direction of the spindle motor 2 the same, so no interruption occurs in the signals input to or output from the disk 1. However, if the disk L is installed with the front and back reversed,
The spindle is rotated in a predetermined direction, and the direction of movement of the tracks on each surface is reversed. When playing back a recorded disc, the order of the playback signals is reversed, making it impossible to play back correctly. Furthermore, when recording a signal on an empty track, there will be an area recorded toward the outer circumference and an area recorded toward the inner circumference on the same surface, making management difficult.

The present invention has been made in view of the above points, and an object of the present invention is to provide a double-sided disc and its recording/playback device that can determine the mounting direction of the disc and correctly record and playback regardless of the mounting direction of the disc. .

Means for Solving the Problems The double-sided disk according to claim 1 is a disk in which tracks are formed in advance in a spiral shape on both sides of the disk, and the direction and shape of the spiral of the tracks as seen from the recording/reproducing surface are different from the front and back surfaces. The double-sided disc according to claim 2 is the double-sided disc according to claim 1, characterized in that the discs are the same and have a surface identification signal on a predetermined surface. The recording and reproducing apparatus according to claim 3 is a recording and reproducing apparatus for recording or reproducing signals on the double-sided disc according to claim 1, comprising: a detector for detecting a side identification signal; A claim characterized by comprising: a determination circuit that determines the rotation direction of the spindle motor based on the determined surface; and a motor drive circuit that rotates the disk in a predetermined direction based on a motor control signal from the control circuit. The recording device described in item 4 is a device for recording signals on a master disk for producing a read-only disk, and includes an operation unit for specifying the surface of the disk on the master disk to be recorded, and a spindle motor according to the surface specification. A double-sided disk according to claim 5, further comprising a control circuit that determines the rotational direction of the disk and the initial position and transfer direction of the transfer unit including the objective lens, and has a control circuit that transmits a signal from the inner circumference to the outer circumference on the front and back surfaces. The disk has a recorded surface on one side and a surface on which signals are recorded from the outer circumference toward the inner circumference on the other side, and has a surface identification signal on a predetermined surface.

A double-sided disc according to a sixth aspect of the invention is the double-sided disc according to the fifth aspect, characterized in that the surface identification signals are concentric circles.

According to the configuration of claim 1, a disk with spiral tracks formed in advance on both sides of the disk is provided with a side identification signal, so even if the disk is mounted on either side, the recording/reproducing device will not be able to identify the side.・When recording or playing back from one side of a disk to another, it is possible to input signals to or output signals from the optical head in the correct order without changing the rotation direction of the spindle motor. I can do something.

According to the structure of claim 2, when the double-sided disc is inserted into the recording/reproducing apparatus, since the surface identification signal of the double-sided disc is made concentric, the surface can be identified without rotating the spindle motor, and the signal can be recorded. Alternatively, the spindle motor can be rotated in the correct direction at the same time as playback starts.

According to the structure of claim 3, by inserting the double-sided disc according to claim 1, the side identification signal is detected and the side is determined, so that one side of the double-sided disc is recorded or played first. If given instructions, the double-sided disc can be rotated in the correct direction.

According to the configuration of claim 4, the surface of the disk is specified on the master disk to be recorded, and the direction of rotation of the spindle motor and the initial position and direction of transfer of the transfer section including the objective lens as the recording head are corrected, respectively. Since the condition can be determined, it is possible to manufacture a double-sided playback-only disc from this master disk, which has the same spiral direction and shape of the track as viewed from the playback surface on the front and back sides.

According to the structure of claim 5, signals can be recorded or reproduced on a double-sided disc by having a surface on one side on which signals are recorded from the inner circumference toward the outer circumference and a surface on the other side on which signals are recorded from the outer circumference toward the inner circumference. When recording and reproducing signals, the direction of rotation of the spindle motor must not be changed midway (recording and reproducing can be performed continuously on both sides of the disc.Furthermore, by providing a surface identification signal on a predetermined surface, it is possible to record and reproduce signals on both sides of the disk. It is possible to detect or determine the initial position.

According to the structure of claim 6, when the double-sided disc of claim 5 is inserted into a recording/reproducing device, the surface identification signal of the double-sided disc is made concentric, so that the surface can be identified without rotating the spindle motor. .

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. First, a recordable/reproducible disk will be described. Groove-like tracks are formed in advance on this type of disk in a spiral shape, and signals are recorded and reproduced by directing a light beam along the groove-like tracks.

The disks used in this example are shown in FIGS. 1(a) and (b). In FIG. 1, l is the disk, 1d is the rotation direction as seen from the detector 3C, and 1e is the rotation as seen from the same direction. direction, and Ic indicates the center hole. For example, FIG. 1(a) is the A side, and the back side (B) is the B side. The track on side A is 7a, and the track on side B is 7b. As shown in FIG. 1, the spiral direction of the track viewed from each side is the same.

In other words, in a state in which no signals are recorded, the disk 1a having the A side and the disk 1b having the B side are the same disk. A double-sided disc 1 is manufactured by pasting together a disc 1a and a disc lb. In this embodiment, it is assumed that the standard rotation direction is to rotate the A side counterclockwise when viewed from the side where the spindle motor is not provided. At this time, the back B side rotates clockwise. On side A, the signal spreads outward as the track rotates, so the signal is recorded from the inner circumference to the outer circumference. On side B, the track contracts inward as it rotates, so signals are recorded from the outer circumference to the inner circumference. Next, the surface identification signal provided on this double-sided disc will be explained with reference to FIG. In FIG. 2, data is recorded on the disc 1 between the outermost circumference 8 of the signal recording area and the innermost circumference 9 of the signal recording area. The surface identification signal is recorded inside the signal recording area. The surface identification signal can form marks by interrupting the grooves of the track. Since the track grooves are formed at a pitch of several microns, when light from the detector is incident on these portions, the reflected light is diffracted, reducing the amount of light received by the detector. Since the portion without grooves remains flat, the amount of reflected light does not decrease. If the size of the mark is about several mm2, it can be detected with a simple reflected light detector. By rotating the disk, the surface can be determined based on whether or not the amount of reflected light changes or the number of times the reflected light changes during one rotation. In this embodiment, as shown in FIG. 2(a), one groove is formed on surface A, and the surface identification signal 1 is
0a, and as shown in FIG. 2(,b), two areas are formed on the B side to form a surface identification signal 10b.

Next, a recording and reproducing apparatus using the double-sided disk produced as described above will be described. FIG. 3 is a block diagram showing the configuration of the recording/reproducing apparatus in this embodiment. In FIG. 3, 1 is a double-sided disk, 3C is a detector, 11 is a determination circuit, 6 is a control circuit, 5 is a motor drive circuit, 2 is a spindle motor, 4 is a transfer drive circuit, 3a, 3b
1 is an optical head, and 12 is an operation section.

When loading the double-sided disc l into a recording/reproducing device,
Commands are issued from the operation unit 12. For example, the disc is loaded by opening a tray (not shown) and placing the disc on it. The operation unit 12 notifies the control circuit 6 by a control command signal that a disk has been mounted. The control circuit 6 is
A motor control signal is output to the motor drive circuit 5 to rotate the disk. Since either direction of rotation is acceptable, it is sufficient to determine it in advance. Further, the rotation speed may also be different from that during signal recording and reproduction, and may be set in advance.

If the rotation speed is low, the start-up time of the motor will be shorter, so the waiting time until the motor starts rotating normally can be shortened. The motor drive circuit 5 rotates the spindle motor 2 according to the motor control signal. The detector 3c is a reflective photodetector, which emits light toward the disk and receives reflected light from the disk. The detector 3C is arranged so that the light from the detector is incident on the radial position where the surface identification signals 10a, 10b shown in FIG. 2 are recorded. As the disk rotates, the amount of light received by the detector 3c changes depending on the mark of the surface identification signal. The detector 3c outputs a reproduction signal proportional to the amount of received light to the determination circuit 11. The determination circuit 11 determines whether the side identification signal is for side A or side B based on changes in the reproduced signal. In this embodiment, if the reproduction signal changes once per revolution, it is determined to be the A side, and if it changes twice per revolution, it is determined to be the B side. The determination result is sent to the control circuit 6 as a surface determination signal. The control circuit 6 sets the rotation direction of the spindle based on the surface determination signal. If the surface determination signal is the A side, the spindle motor 2 is set to rotate counterclockwise when viewed from the detector 3c side, and if it is the B side, the spindle motor 2 is set to rotate clockwise. Commands for the surface to be recorded or reproduced and the position on the surface (address, chapter, etc.) are issued from the operation unit 12. When the control circuit 6 receives a recording or reproduction control command signal, it outputs a motor control signal to the motor drive circuit 5 so that the motor rotates in a set direction. The motor drive circuit 5 controls the spindle motor 2 to rotate in a set rotation direction. In addition, the control circuit 6 determines the surface to be accessed from the control command signal and the position on that surface (
(given as an address). The commanded surface is compared with the surface indicated by the surface determination signal, and it is determined whether the surface corresponds to the top or bottom surface of the disk. A transfer control signal is output to the transfer drive circuit 4 so as to move the optical heads 3a, 3b on the corresponding surfaces to specified positions. The transfer drive circuit 4 moves the corresponding optical head 3a according to the transfer control signal.

3b to the specified position and start recording or playback.

As described above, according to this embodiment, a surface identification signal is recorded on the inner peripheral portion of a double-sided disc, and when the disc is loaded, the disc is slightly rotated to reproduce the surface identification signal, thereby making it possible to determine the surface. By rotating the disk in the correct direction, the optical head can access the specified surface.

Next, a second embodiment of the present invention in which the surface identification signal recording method is different will be described.

The disk used in this embodiment will be explained with reference to FIGS. 4(a) and 4(b). In Fig. 4, the disk of this embodiment is 13
It is expressed as Disk center hole 13c, signal recording area 8
．． 9 is similar to IC1 in FIG. 1 and 8.9 in FIG. 2. In this embodiment, the surface identification signal is recorded concentrically inside the signal recording area.

Concentric marks can be recorded by continuously forming track grooves over a width of several mm.

In this embodiment, as shown in FIG. 4(a), one concentric mark +3d is made as a surface identification signal on the A side, and on the B side of FIG. 4(b), which represents the back side of the A side, the A concentric mark 13e is also made, and a total of two marks are used as a surface identification signal.

Next, a recording and reproducing apparatus using a double-sided disc according to this embodiment will be explained. FIG. 5 is a block diagram showing the configuration of the main parts of the recording/reproducing apparatus in this embodiment. In FIG. 5, 13 is a double-sided disk, 3d and 3e are detectors, and 1
1 is a determination circuit. The configuration of other parts of the recording/reproducing apparatus is the same as the configuration shown in FIG. 3, and therefore illustration thereof is omitted.

The double-sided disc 13 is loaded into a recording/reproducing device. The detectors 3d and 3e are reflective photodetectors, which emit light toward the disk and receive reflected light from the disk. As shown in FIG. 5, the detector 3d is arranged so that the light from the detector is incident on the position where the concentric mark +3d of the surface identification signal is recorded. Similarly, the detector 3e is arranged so that the light from the detector is incident on the position where the concentric mark 13e of the surface identification signal is recorded. It is easy to arrange the detectors in this way if the width of each mark is set to a certain extent. In this embodiment, since the marks are concentric, there is no need to rotate the disk. By determining the amount of light received by each detector after the disk is loaded, that is, the level of the reproduction signal, it is possible to detect the presence or absence of a mark signal. Each of the detectors 3d and 3e outputs a reproduction signal proportional to the amount of light received by a judgment circuit 11.
Output to. The determination circuit 11 compares the level of the reproduced signal with a reference value, and determines that the side is A when the level of the reproduced signal from the detector 3d is low and the level of the reproduced signal from the detector 3e is high.
If both reproduction signal levels are low, it is determined that it is side B. Further, if the levels of the two reproduction signals are both high, it can be determined that the disc is not a double-sided disc according to the present invention but another disc. The determination result is made into a surface determination signal and sent to the ζ control circuit 11.

The control circuit 11 sets the rotation direction of the spindle based on the surface determination signal. The subsequent reproduction or recording operations are the same as those in the first embodiment, so the explanation will be omitted.

As described above, according to this embodiment, by recording the surface identification signal in the form of concentric marks on the inner circumferential portion of the double-sided disc, the surface can be immediately determined when the disc is loaded. Since there is no need to rotate the disc, there is no waiting time to determine the side, and recording or reproducing operations can be started immediately after the disc is loaded.

Next, the case of a read-only disc will be explained.

This type of disk does not have groove-like tracks, but the focused points of recorded signals line up to form tracks.

Also, read-only discs are manufactured by copying from a master disc, but recording devices that record signals on the master disc can usually record only on one side. The configuration of this embodiment of the recording device is explained in the sixth section.
As shown in the figure. In FIG. 6, 15 is an operating section, 6 is a control circuit, 4 is a transfer drive circuit, 5 is a spindle motor drive circuit, 2 is a spindle motor, 16 is an objective lens section, 17 is a mirror, 18 is an optical modulator, 19 is a laser. In the master recording device, a gas laser 19 is used as a light source. The optical modulator 18 modulates the light beam emitted from the laser 19 by changing the transmittance based on an input signal (not shown). The modulated light beam is reflected by the mirror 17, enters the objective lens 16, focuses it onto the master disk 14,
Record the signal on the master disc. When recording a signal on the master disc, the operating unit 15 specifies which side of the disc to be produced or the input side B side. When plane A is specified, the control circuit 6 outputs a motor control signal to the motor drive circuit 5 so that the spindle motor 2 rotates counterclockwise when viewed from the side where the objective lens 16 is located. The motor drive circuit 5 controls the spindle motor 2 to rotate in a set rotation direction. The control circuit 6 also includes an objective lens 16 and a mirror 17.
A transfer control signal is output to the transfer drive circuit 4 so as to move the transfer unit to the area where the surface identification signal is to be recorded. The transfer [live circuit 4] moves the transfer unit according to the transfer control signal. The surface identification signal explained in the previous embodiment is recorded.

Next, the transfer section is moved to the innermost circumferential position of the signal recording area, and the signal is recorded while moving the transfer section toward the outer circumference from there. When plane B is specified, the control circuit 6 outputs a motor control signal to the motor drive circuit 5 so that the spindle motor 2 rotates clockwise when viewed from the side where the objective lens 16 is located. The motor drive circuit 5 controls the spindle motor 2 to rotate in a set rotation direction. Further, the control circuit 6 sends a transfer control signal to the transfer drive circuit 4 so as to move the transfer unit to the outermost position of the signal recording area.
Output to.

The transfer drive circuit 4 moves the transfer section according to the transfer control signal. From there, the signal is recorded while moving the transfer section toward the inner circumference. When the recording of the signal is completed, the transfer unit is moved to the area where the surface identification signal is to be recorded, and the corresponding surface identification signal is recorded.

A double-sided disc is produced by copying the disc from the master disk produced in the above manner by pasting side A, on which signals are recorded from the inner circumference to the outer circumference, and side B, on which signals are recorded from the outer circumference to the inner circumference. do.

In addition, as mentioned above, it is possible to create a double-sided disc for playback only by pasting together two discs for side A and B that are copied from the original disc, or to create a double-sided disc for playback only, or a disc with recording or playback media on both sides of the disc. A double-sided disk having a double-sided structure may be used as a double-sided disk for recording or reproduction by recording on one side of each side of △ and B using a recording apparatus as shown in FIG.

Furthermore, in this embodiment, the surface identification signal is recorded by the presence or absence of track grooves, but is not limited to this. For example, a similar mark may be printed on a label attached to the disc, or the disc may be used by placing it in a cartridge. In this case, an identification signal may be added to the cartridge.

According to the double-sided disc according to claim 1, as described above, the effects of the invention are as follows.
It is a disk in which tracks are pre-formed in a spiral shape on both sides of the disk, and the spiral direction and shape of the track as seen from the recording/reproducing surface are the same on the front and back surfaces, and a surface identification signal is provided on a predetermined surface. The recording/reproducing device can determine the side even if the disk is installed both front and back, and when recording or reproducing from one side of the disk to the other, it can record or play back in the correct order without changing the direction of rotation of the spindle motor. Since signals are input to and output from the optical head, this disc is used as a medium for recording and reproducing long-term signals that require continuous recording and reading of signals on both sides of the double-sided disc. Ru. If used as an audio or video disc, it can be used as a disc for long-term continuous performance or continuous screening.

According to the recording/reproducing apparatus according to claim 3, there is provided a detector for detecting a surface identification signal of a double-sided disc, a determination circuit for determining the surface from the detected surface identification signal, and a rotation direction of the spindle motor based on the determined surface. and a motor drive circuit that rotates the disc in a predetermined direction by a motor control signal from the control circuit. Signals can be recorded or played back seamlessly on the front and back sides. In this case, when a double-sided disc is inserted into this recording/playback device, the A side.

It automatically records or plays back signals from the correct direction without being affected by the direction of the B side.

Further, in the double-sided disc according to the second aspect, since the surface identification signals are concentric, when the double-sided disc is inserted into the recording/reproducing apparatus according to the third aspect, the A side can be recognized without rotating the spindle motor.

The B side can be distinguished, and the optical head can be moved in a predetermined transport direction from the beginning and kept in standby at the initial position. Also,
Even when a disk from another system of a different type is inserted, this can be detected immediately.

Next, according to the recording device according to claim 4, there is provided a device for recording signals on a master disc for producing a read-only disc, and an operation unit for designating a surface of the disc on the master disc to be recorded; A control circuit is provided which determines the rotation direction of the spindle motor and the initial position and transfer direction of the transfer unit including the objective lens, and the front and back surfaces reverse the rotation direction of the spindle motor and the transfer direction of the transfer unit to generate a signal. Since it is characterized by recording, it is possible to produce a read-only double-sided disc using this master disc, in which the spiral direction and shape of the tracks viewed from the playback surface are the same on the front and back sides.

This makes it possible to easily produce master discs for pressing large quantities of playback-only double-sided discs that can be played continuously on both sides of the disc.

Further, according to a double-sided disc according to claim 5, the disc has one side on which signals are recorded from the inner circumference to the outer circumference and the other side on which signals are recorded from the outer circumference to the inner circumference, Since it has a surface identification signal on the surface, when recording or reproducing signals on a double-sided disc, the direction of rotation of the spindle motor does not need to be changed during the process. Signals can be input to and output from the optical head in the correct order without being affected by the orientation of the B surface. As a result, the double-sided disc can be used as a reproduction-only medium for long-time signals that require continuous reading of signals from both sides of the disc.

Since the double-sided disc according to claim 6 has a concentric surface identification signal, when it is inserted into the playback device according to claim 3, the A-side disc can be recognized without rotating the spindle motor.
The B side can be distinguished, and the optical head can be moved in a predetermined transport direction from the beginning and kept in standby at the initial position.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of a double-sided disc in an embodiment of the present invention, FIG. 2 is a schematic diagram showing a side identification signal of a double-sided disc in an embodiment of the present invention, and FIG. 3 is a schematic diagram showing the configuration of a double-sided disc in an embodiment of the present invention. A block diagram of a recording/reproducing apparatus for a double-sided disc according to an embodiment, FIG. 4 is a schematic diagram showing a side identification signal of a double-sided disc according to another embodiment of the present invention, and FIG. 5 is a diagram of a double-sided disc according to another embodiment of the present invention. FIG. 6 is a block diagram of a recording device for a master of a read-only disc in an embodiment of the present invention, and FIG. 7 is a diagram showing the structure of a disc in an embodiment of the prior art. , FIG. 8 is a block diagram of an apparatus for recording and reproducing the disk having the configuration shown in FIG. 7, FIG. 9 is a diagram showing the configuration of a disk in another conventional embodiment, and FIG. FIG. 11 is a block diagram of a device for recording and reproducing a disc; FIG. 11 is a diagram showing the structure of a disc in another conventional embodiment;
This figure is a block diagram of an apparatus for recording and reproducing a disc having the configuration shown in FIG. 11. 1, 13.14-...Double-sided disc, la, lb, +3
a. 13b...disk, Id, le...optical head 3a
Rotation direction as seen from the optical head 3, Ig, 1h... Rotation direction as seen from the optical head 3, 2... Spindle motor, 3c, 3d3
e...Detector, 4...Transfer drive circuit, 5...Motatribe circuit, 6...Control circuit, 7a, 7b...
Track, 10a, 10b, +3d, 13
e -... Surface identification signal, 11... Judgment circuit, 12...
Operation unit, 16... Objective lens, 17°°° Mihu 18... Light modulator, 19... Laser. Agent Yoshihiro Morimoto Figure 1 (ln () 2 no. ,,-Mar 2 Fig. C [Tonneau Fig. 1 Fig. 70 Fig. f Fig. 72

Claims (1)

[Claims] 1. A disk in which tracks are pre-formed in a spiral shape on both sides of the disk, the direction and shape of the spiral of the tracks as seen from the recording/reproducing surface are the same on the front and back surfaces, and Double-sided disc with side identification signal. 2. The double-sided disc according to claim 1, wherein the surface identification signals are concentric. 3. A recording and reproducing apparatus for recording or reproducing signals on the double-sided disc according to claim 1, comprising: a detector for detecting a side identification signal; a determination circuit for determining a side from the detected side identification signal; and a determined side. A recording/reproducing device comprising: a control circuit that determines the rotational direction of a spindle motor; and a motor drive circuit that rotates a disk in a predetermined direction based on a motor control signal from the control circuit. 4. A device for recording signals on a master disc for producing a read-only disc, which includes an operation unit for specifying the surface of the disc on the master disc to be recorded, and a rotating direction of a spindle motor and an objective lens according to the designation of the surface. A read-only disk comprising a control circuit for determining an initial position and a transfer direction of a transfer section, and recording a signal by reversing the rotational direction of the spindle motor and the transfer direction of the transfer section depending on the front and back surfaces. Recording device. 5. A double-sided disc having a surface on which signals are recorded from the inner circumference toward the outer circumference and a surface on which signals are recorded from the outer circumference toward the inner circumference on the other side, the disk having a surface identification signal on a predetermined surface. 6. The double-sided disc according to claim 5, wherein the surface identification signals are concentric.