Disk format detecting device and method

Abstract: An optical disk reproducing apparatus having playback systems of CD and DVD containing their respective sync signals. The systems respectively have sync detectors (51, 522), and analyze a sync signal output from the sync detectors (521, 522) when a disk (20) is detected to be mounted. The CD playback system (513-515) is selectively driven when a CD sync signal is detected to perform a CD playback mode, and the DVD playback system (516-518) is selectively driven when a DVD sync signal is detected to perform a DVD playback mode.

Description: The present invention relates to a disk reproducing apparatus and method and, more particularly, to a device and method of automatically detecting the kinds of disk mounted in an apparatus for reproducing a plurality of disks. Generally, the so-called compact disk (CD) is the representative type of optical disk for performing non-contact reading by using a laser beam. However, for disk recording/reproducing apparatus, higher speeds, overwriting and higher density (larger capacity) are increasingly required. Meanwhile, for digital video compression technology, MPEG (Moving Picture Experts Group) has become in more practical use. Accordingly, digital moving picture disk media like a digital video disk (DVD) will emerge as the core media of multimedia storage. Figure 1 is a block diagram of a DVD player. In this figure disk 20 is a high-density optical disk, which can be DVD in this case. Pickup unit 111 is a shortwave optical head. It is assumed that the numerical aperture is 0.6, and that the red semiconductor laser wavelength be used. Signal amplifier 112 amplifies a light signal output from pickup unit 111 after converting it into an electrical signal. Demodulator/ECC decoder 113 demodulates the modulated signal output from signal amplifier 112, and corrects the error produced during playback. Servo controller 114 receives the output (focusing&tracking error signal) of signal amplifier 112 and the output (constant linear velocity control signal) of demodulator/ECC decoder 113 in order to control pickup unit 111. System decoder 116 decodes the DVD data stream output from demodulator/ECC decoder 113, the stream being divided into video (elementary) data stream and audio (elementary) data stream. Video decoder 117 decodes the video data stream output from system decoder 116 so that it is converted into the form of video data reproducible. Encoder 118 encodes the video data output from video decoder 117 into a corresponding video displaying mode (NTSC or PAL), and then outputs them to a display. Audio decoder 119 converts the audio data stream encoded and output from system decoder 116 into the original data. D/A converter 120 converts the data output from audio decoder 119 into an analog audio signal. In Figure 1 the system controller for controlling the overall operation of the disk reproducing apparatus is not shown. The DVD player constructed as above uses modulation, error correction and video encoding different from those of a general CD player so that their signal processings are completely different. The pit size and track pitch of DVD and CD are different, and their pickup unit 111's laser wavelength and the numerical aperture of the objective lens are different. In the DVD recording/reproducing apparatus, it is important to reduce the size of focusing spot for the purpose of higher density. For this, first, the laser wavelength becomes shorter, secondly, the objective lens' numerical aperture becomes larger, and thirdly, a modulation having an excellent encoding efficiency is used. Here, for DVD the laser wavelength is 650-635nm of red semiconductor laser, the objective lens' numerical aperture is 0.6, and EFM-plus (Eight to Fourteen Modulation plus) is used for modulation. In order to reproduce information from the high-density optical disk, pickup unit 111 should be able to form a small focusing spot. The diameter of the focusing spot is proportional to the wavelength λ of light, and inversely proportional to the objective lens' numerical aperture, as shown in Figure 2. At present the lower limit of the semiconductor laser wavelength is about 635nm, as described above. Generally speaking, the DVD uses 650nm of laser wavelength as its standard, CD doing 780nm of laser wavelength. The DVD's numerical aperture is 0.6, and the CD's is 0.45 so that the DVD's diameter of focusing spot becomes over about 60% of the CD's. Therefore, the DVD can obtain a playback signal equal to the CD's at about 2.6 times the recording density of the CD. The DVD improves the waveform of playback signal through the actual circuit processing so that it has a recording density about 4.2 times the CD's. The characteristics of DVD and CD are shown in the following table 1. CD DVD REMARKS DISK DIAMETER 120mm 120mm DVD is a both-sided multi-layer. DISK THICKNESS 1.2mm 0.6mm RECORDING CAPACITY 640Mbyte 4.7Gbyte In case of single-sided single layer LASER WAVELENGTH 780nm 650nm OBJECTIVE'S NUMERICAL APERTURE 0.45 0.6 MINIMUM PIT SIZE 0.9µM 0.4µM TRACK PITCH 1.6µM 0.74µM MODULATION MODE EFM EFM-plus ERROR CORRECTING MODE CIRC RS-PC In the table 1, the CD and DVD of the same disk diameter have many differences. However, their compatibility is very important because CD has an enormous amount of soft resources. The primary impedance in the compatibility between DVD and CD is to use a separate optical pickup. In other words, in order to reproduce information on disk, part of the optical system is formed according to the thickness of disk. For this reason, the objective lens is designed in accordance with the thickness of disk. If the thickness of disk deviates from the value designed, spherical aberration is produced, and the convergence of optical focus is decreased. More specifically, DVD is 0.6mm-thick, whereas CD is 1.2mm-thick so that the two kinds of disk cannot be reproduced with a single pickup unit. For their compatibility, separate optical pickup units must be used. In order to overcome such a problem, a double-focus optical unit has been suggested for use with both CD and DVD. In the optical pickup unit shown in Figure 4, the optical focus for DVD and the optical focus for CD are formed spaced apart by a predetermined distance in the direction of optical axis. This solves the problem caused by the difference of thickness of disk. The principle of the double-focus optical pickup shown in Figure 4 is to overlap the operations of two kinds of lens by using a hologram. The numerical aperture of the objective lens of the optical pickup is 0.6 in accordance with the standards of DVD, and a hologram is provided to diffract part of its central light as if a lens refracts it. The light not diffracted by the hologram is converged by the objective lens whose numerical aperture is 0.6, to thereby form the optical focus of DVD. The diffracted light forms a hologram to be suitable for 0.4 numerical aperture of the hologram and objective lens and 1.2mm-thick CD. In case of the optical pickup shown in Figure 4, the optical focus for CD is formed farther away than that for DVD. Here, the photodetector is disposed so that the reflection image of the optical focus converged on the disk is formed thereon. If the DVD is reproduced, the optical focus of DVD is converged on the disk, and the optical focus for CD deviates so that the image becomes unclear. The image of the optical focus for DVD is formed on the photodetector but the reflection light at the optical focus for CD is scattered widely to give no external impacts in DVD's playback. The reverse operation is performed in CD's playback. In case of a system having a pickup capable of reproducing both DVD and CD or pickups capable of independently reproducing DVD and CD, it should be operated in a corresponding mode by detecting the kind of disk inserted. The discrimination of DVD and CD can be implemented in various ways: to compare the sizes of the focus error detection signals reproduced by the optical pickup; or to compare the sizes of RF signals in accordance with the pit size. However, the aforesaid method has disadvantages in that a long time is required to make a distinction between CD and DVD and also, accuracy is reduced. EP 0 521 236 describes methods and apparatus for identifying the signal format of a signal read from any one of a plurality of video disks. The signal formats include NTSC, PAL and MUSE. A disk is rotated at a rotational speed required for one of the signal formats, and it is judged whether or not signal processing corresponding to the format of that rotation speed is appropriate for the read signal. This process is repeated at different rotational speed until correct signal processing for the read signal is identified. EP 0 691 652 describes an apparatus for replaying recording media in the form of compact disks. The recording media have video or audio data recorded thereon, together with discrimination data indicating the kind of the recording medium. In order to overcome or reduce such disadvantages of the prior art, it is an aim of embodiments of the present invention to provide a device and method of automatically detecting the kinds of disk mounted in a system for reproducing multiple kinds of disks. It is another aim of embodiments of the present invention to provide a device and method of detecting and analyzing the sync pattern of a mounted disk after a CD mode is set initially in a system for reproducing DVD and CD, to thereby detect the kind of the disk mounted and also automatically perform the corresponding disk reproducing mode according to the discrimination result. It is still another aim of embodiments of the present invention to provide a device and method of detecting and analyzing the sync pattern of a mounted disk after a DVD mode is set initially in a system for reproducing DVD and CD, to thereby detect the kind of the disk mounted and also automatically perform the corresponding disk reproducing mode according to the discrimination result. It is a further aim of embodiments of the present invention to provide a device and method of detecting and analyzing the sync pattern of a mounted disk in a disk reproducing system having CD and DVD sync detectors, to thereby detect the kind of the disk mounted and also automatically perform the corresponding disk reproducing mode according to the discrimination result. According to a first aspect of the present invention there is provided an optical disk reproducing apparatus, characterised in that: the apparatus comprises playback systems of CD and DVD containing their respective sync signals, the CD and DVD playback systems respectively having sync detectors, the systems analyzing a sync signal output from the sync detectors when a disk is detected to be mounted, the CD playback system being selectively driven when a CD sync signal is detected to perform a CD playback mode, the DVD playback system being selectively driven when a DVD sync signal is detected to perform a DVD playback mode. Preferably, the CD playback system is arranged to analyze whether a CD sync signal output from the CD sync detector is detected or not when a disk is detected to be mounted and be selectively driven when the CD sync signal is detected to perform a CD playback mode, and, the DVD playback system is arranged to be selectively driven when the CD sync signal is not detected for a predetermined time to perform a DVD playback mode. Preferably, the DVD playback system is arranged to analyze whether a DVD sync signal output from the DVD sync detector is detected or not when a disk is detected to be mounted and be selectively driven when the DVD sync signal is detected to perform a DVD playback mode, and, the CD playback system is arranged to be selectively driven when the DVD sync signal is not detected for a predetermined time to perform a CD playback mode. Preferably, the optical disk reproducing apparatus further comprising an optical pickup arranged to be controlled for CD-only reproduction as the playback systems analyze the sync signal output from the sync detectors. Preferably, the optical disk reproducing apparatus further comprises an optical pickup arranged to be controlled for DVD-only reproduction as the playback systems analyze the sync signal output from the sync detectors. Preferably, the optical disk reproducing apparatus comprises a double focus optical pickup. For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 is a block diagram of a digital video disk reproducing apparatus; Figure 2 is a diagram for explaining the relationship among the wavelength of light, the numerical aperture of the objective lens, and the diameter of the optical focus in the digital reproducing apparatus; Figure 3 is a diagram for explaining the relationship between pit and optical focus with respect to video disk and compact disk; Figure 4 is a diagram for explaining the principle of double-focus optical pickup; Figure 5 is a block diagram of a device for detecting the kind of disk mounted in a disk player according to the first embodiment of the present invention; Figures 6A-6E show the characteristics of detecting CD frame sync signal in order to detect the kind of disk according to the first embodiment; Figure 7 is a block diagram of a device for detecting the CD frame sync signal according to the embodiment of the present invention; Figure 8 shows a flowchart of explaining the operation of detecting the kind of disk mounted in the disk player; Figure 9 is a block diagram of a device for detecting the kind of disk mounted in a disk player according to the second embodiment of the present invention; Figure 10 is a diagram of showing an example of DVD sync pattern; Figures 11A-11C show the characteristics of detecting CD frame sync signal in order to detect the kind of disk according to the second embodiment; Figure 12 shows a flowchart of explaining the operation of detecting the kind of disk mounted in the disk player according to the second embodiment; Figure 13 is a block diagram of a device for detecting the kind of disk mounted in a disk player according to the third embodiment of the present invention; and Figures 14A and 14B show a flowchart of explaining the operation of detecting the kind of disk mounted in the disk player according to the second embodiment. Figure 5 shows a system configuration for automatically detecting the kind of disks mounted in the first embodiment of disk recording/reproducing system having CD and DVD reproducing systems. It is assumed that optical pickup 111 uses CD/DVD optical pickup unit. Radio frequency (RF) receiver 512 amplifies a weak light signal reproduced from optical pickup 111. Here, the RF signal output from RF receiver 512 is a signal reproduced from the CD or DVD. First, in the DVD reproducing system, DVD equalizer 516 filters the DVD band of the RF signal received, and equalizes it. Here, the DVD band becomes a wide band containing the CD band. DVD signal processor (digital signal processor) 517 receives the DVD band of data stream output from DVD equalizer 516 to thereby demodulate the data modulated and correct errors produced during the above procedure. DVD signal processor 517 corresponds to demodulator/ECC corrector 113 shown in Figure 1. A/V decoder 518 splits the data output from DVD signal processor 517 into video data and audio data, and signal processes them. A/V decoder 518 corresponds to system decoder 116, video decoder 117 and audio decoder 119. Secondly, in the CD reproducing system, CD equalizer 513 filters the CD band of the RF signal output from RF receiver 512, and equalizes it. CD signal processor (digital signal processor) 514 demodulates the modulated data stream output from CD equalizer 513, and corrects errors produced during the above procedure. Audio signal processor 515 signal processes the data output from CD signal processor 514. This embodiment of the disk reproducing apparatus has CD and DVD reproducing systems. Optical pickup 111 is a unit capable of reproducing both CD and DVD. If a disk is mounted on the disk reproducing apparatus, it should be determined whether the disk mounted is CD or DVD, and then a corresponding reproducing system should be selectively driven. For this, CD sync detector 521 is incorporated in CD signal processor 514. Controller 511 decides the kind of the disk mounted and selectively drives a corresponding reproducing system, depending upon whether the CD frame sync pattern output from CD sync detector 521 is detected or not. For the frame sync pattern of CD a pattern not produced from the modulated data is used. This ensures reliable synchronization unless bit errors are produced. The data recorded on CD uses EFM modulation. According to the EFM modulation, eight bits of data are converted into 14 bits, and pattern combination of minimum three bits 3T and maximum 11 bits 11T is enabled. For the CD frame sync pattern, "1000000000010000000000100 B " (11T+11T+2T) not used as data and shown as 6a in Figure 6 is used. The CD sync pattern shown as 6a is recorded in the CD in the form of 6b or 6c of Figure 6. The format of data recorded on the CD is made as 6d of Figure 6. CD sync detector 521 is formed as in Figure 7. Referring to Figure 7, a data stream input is applied to input register 71 and shifted. Reference register 72 stores the CD frame sync pattern shown as 6a of Figure 6. Comparator 73 compares pieces of parallel output bit data of input register 71 and pieces of parallel output bit data of reference register 72, and outputs the result signal of comparison in units of bit. Sync signal detector 74 logically combines the bit data output from Comparator 73, and generates a signal for deciding whether the CD sync signal is detected or not. Here, sync signal detector 74 uses a gate circuit. In case that HIGH logic signals are all output from Comparator 73 in sync detection, sync signal detector 74 uses an AND gate. If the CD frame format is formed as 6d of Figure 6, CD sync detector 521 detects a CD sync signal in the sync pattern cycle shown as 6e of Figure 6. The sync signal is generated in the cycle of 13.3ms. The signal output from CD sync detector 521 formed as in Figure 7 is applied to controller 511. Controller 511 sets the CD mode as its initial mode if the disk is detected to be mounted. At a time point when the constant linear velocity (CLV) servo of the CD mode is ON, the frame sync signal of the reproducing system is produced in the cycle of 13.3ms. More specifically, in case that data and their sync pattern are recorded on the CD as 6d in Figure 6, the frame sync signal is detected in the cycle of 13.3ms during playback, as mentioned above. The frame sync signal is generated from all the disks of CD and VC. Here, the CLV servo is applied at a reference of 11T of the RF signal. When controller 511 sets the CD mode as the initial operation mode, the CD sync pattern can be detected normally in case that the disk mounted is CD. However, if the DVD is mounted while the CD mode is set, the frame sync signal cannot be detected while the CLV servo is applied. In this embodiment, after the CLV servo is applied when the disk is mounted while the initial driving mode is CD mode, it is determined whether the sync signal reproduced is detected or not, so as to decide whether the current mode is CD or DVD. According to the result decided, the CD or DVD reproducing mode is selectively driven. Figure 8 shows the procedure of selectively driving a corresponding playback mode by controller 511's detecting the kind of disk mounted. As shown in this figure, it is determined in this embodiment whether the CD frame sync signal is detected or not, after the CD mode is set as the initial playback mode when the disk is mounted. If the sync signal is detected according to the result, it is determined that the CD is mounted so that the CD reproducing system is selectively driven. If the sync signal is not detected for a predetermined time, it is determined that the DVD disk is mounted so that the DVD reproducing system is selectively driven. Referring to Figure 8, controller 511 checks whether any disk is mounted. First of all, controller 511 checks the state of input portion 510 to thereby find out the ON/OFF of the tray. If the tray is ON/OFF, controller 511 detects it in steps 811 and 813, and then decides that the disk is mounted. Thereafter, controller 511 controls a servo controller (not shown) in step 815 so as to perform the optical pickup 111's focusing. Here, optical pickup 111 is a unit usable for both CD and DVD. Therefore, the servo controller drives optical pickup 111 as the CD pickup unit. Controller 511 raises or lowers the optical pickup 111's focusing in step 815, and checks in step 817 whether focus locking is performed. Here, if focus locking is not performed, controller 511 senses this situation in step 817, and decides in step 819 that the disk is not mounted. This case indicates that the tray is ON/OFF by a user while the disk is not mounted. If focus locking is performed in step 817, this state indicates that the disk is mounted on the tray. In this case controller 511 controls the servo controller through steps 821-825 so as to rotate the disk mounted and turn on the tracking servo and CLV servo. Here, the servo controller drives the spindle motor under the control of controller 511 to thereby rotate the disk. In addition, the tracking servo is performed so that optical pickup 111 accurately traces the tracks. If the tracking servo is finished, the rotation speed of disk is controlled by manipulating the spindle motor in the CLV mode of the CD playback mode. This situation shows that the CLV mode of the CD playback mode is set during disk mounting and the detection of CD frame sync signal is prepared. If the CD CLV servo is ON, controller 511 receives the output of CD sync detector 514 in step 827, and checks whether the CD frame sync signal is detected or not. Here, CD sync detector 521 receives the data stream filtered and equalized in the CD band, and the data stream input is compared with the previously stored CD frame sync pattern. Here, the CD frame sync pattern stored in reference register 72 is a peculiar pattern having a format different from the data recorded in the CD. CD sync detector 521 compares the sync pattern with the data stream received so that the pattern having the same value is output as the CD frame sync signal. If the disk mounted is CD, the sync signal output from CD sync detector 521 is generated in the cycle of 13.3ms, as 6e of Figure 6. Controller 511 senses in step 827 that the CD frame sync signal is detected. The sync signal is detected until a predetermined number through steps 829 and 831. The number of detection of the CD frame sync signal is set to be many enough to decide that the disk mounted is CD. If the CD frame sync signal is detected as many as the predetermined number, controller 511 establishes optical pickup 111 as being for CD in step 833, and resets the CLV servo for CD playback. Then, in step 835 DVD signal processor 517 and A/V decoder 518 are controlled to thereby inactivate the DVD playback system, and CD signal processor 514 and audio processor 515 are controlled to thereby activate the CD playback system. By doing so, the CD playback mode is performed. However, if the CD frame sync signal is not detected in step 827, controller 511 checks in step 837 whether the predetermined time passes. This means that the detection of the CD frame sync signal is performed for the predetermined time even when the disk mounted is DVD. Controller 511 waits to detect the CD frame sync signal for the predetermined time after the CD CLV servo is ON. If the sync signal is not detected for this time, the disk mounted is decided to be DVD. The predetermined time is a period in which several CD frame sync signals can be detected. If the CD frame sync signal is not received for the predetermined time, controller 511 senses this state in step 837, and decides in step 839 that the disk mounted is DVD. In step 841 optical pickup 111 is set for DVD, and the DVD CLV servo is ON. If the CLV is locked thereafter, controller 511 senses it in step 843, and in step 845 CD signal processor 514 and audio processor 515 are OFF to stop the operation of the CD playback system. The DVD signal processor 517 and A/V decoder 518 are activated to drive the DVD playback system and perform the DVD playback mode. In the first embodiment described as above, the CD playback mode is first performed when the disk is mounted in a disk playback system for reproducing both the CD and DVD, to thereby check whether there is a CD frame sync signal of the disk. If the CD frame sync signal is detected, the disk mounted is detected to be CD, and the CD playback system is activated to perform the CD playback mode. If not, the disk mounted is decided to be DVD, and the DVD playback system is activated to perform the DVD playback mode. Second Embodiment Figure 9 shows a configuration of automatically detecting the kind of disks mounted in the second embodiment of disk recording/reproducing system having CD and DVD reproducing systems. It is assumed that optical pickup 111 uses a CD/DVD optical pickup unit. Radio frequency (RF) receiver 512 amplifies a weak light signal reproduced from optical pickup 111. Here, the RF signal output from RF receiver 512 is a signal reproduced from the CD or DVD. First, in the CD reproducing system, CD equalizer 513 filters the CD band of the RF signal output from RF receiver 512, and equalizes it. CD signal processor 514 demodulates the data stream modulated and output from CD equalizer 513, and correct errors produced during the above procedure. Audio processor 515 signal processes the data output from CD signal processor 514. Secondly, in the DVD reproducing system, DVD equalizer 516 filters the DVD band of the RF signal received, and equalizes it. Here, the DVD band becomes a wide band containing the CD band. DVD signal processor 517 receives the DVD band of data stream output from DVD equalizer 516 to thereby demodulate the data modulated, and correct errors produced during the above procedure. DVD signal processor 517 corresponds to demodulator/ECC corrector 113 shown in Figure 1. A/D decoder 518 splits the data output from DVD signal processor 517 into video data and audio data, and signal processes them. A/V decoder 518 corresponds to system decoder 116, video decoder 117 and audio decoder 119. This embodiment of the disk reproducing apparatus has CD and DVD reproducing systems. Optical pickup 111 is a unit capable of reproducing both CD and DVD. If a disk is mounted on the disk reproducing apparatus, it should be determined whether the disk mounted is CD or DVD, and then a corresponding reproducing system should be selectively driven. For this, DVD sync detector 522 is incorporated in DVD signal processor 517. Controller 511 decides the kind of the disk mounted and selectively drives a corresponding reproducing system, depending upon whether the CD frame sync pattern output from DVD sync detector 522 is detected or not. For the frame sync pattern of DVD a pattern not produced from the modulated data is used. This ensures reliable synchronization unless bit errors are produced. The data recorded on DVD uses EFM-plus modulation. In the DVD playback system using the EFM-plus modulation, the pattern of genuine data is maximum 11T (100000000001 B ). Therefore, the DVD sync pattern commonly uses a pattern not used in the genuine data. In this case, such a pattern should surpass minimum 12T. The DVD uses multiple sync patterns in combination in an appropriate way. Here, those sync patterns commonly have specific patterns not using the data pattern. It is assumed in this embodiment that the common pattern used in the sync pattern is 14T. The common pattern is assumed to be located at the lower 14 bits of each of the sync patterns. Figure 10 shows an example in which the DVD's sync pattern and pieces of data are stored in one sector format. In Figure 10, reference characters S indicates the sync patterns, D1-D being genuine data. Reference characters a1-a2 represent the length of sync pattern, b1-b2 being the length of data. Reference characters c1-c2 indicates the length of sync frame. Reference character E represents the length of two sync frames. Here, the data length b is far longer than the sync pattern length a. Reference character F indicates the number of rows of two frame syncs forming the sector. It is therefore noted that the size of one DVD sector becomes F*E = (C1+C2)*F =[(a1+b1) + (a2+b2)]*F (here a1=a2, b1=b2) The sector format recorded in the DVD becomes as shown in Figure 10. In this format, the sync pattern is formed as 11a of Figure 11. Here, the sync pattern is formed with bits a, and the lower bits of the sync pattern have 14T commonly. The lower 14 bits of multiple sync patterns used in the DVD have the value. Their upper bits have different values. As shown in 11b and 11c of Figure 11, the data transfer time between the DVD frame sync patterns becomes 1.2ms. DVD sync detector 522 for detecting the DVD frame sync patterns shown in Figures 10 and 11 can be implemented in the same configuration as CD sync detector 521 shown in Figure 7. In this case reference register 82 of DVD sync detector 522 stores pieces of lower 14 bit data having a common value in the DVD frame patterns, as shown in Figure 11a. Comparator 73 compares pieces of parallel output playback data stream of input register 71 and the DVD frame sync pattern of reference register 72, and outputs the result signal of comparison in units of bit. Sync signal detector 74 logically combines the bit data output from Comparator 73, and generates a signal for deciding whether the DVD sync signal is detected or not. If the DVD sector format is formed as in Figure 10, DVD sync detector 522 detects a DVD frame sync signal in the sync pattern cycle shown as 11c of Figure 11. The DVD frame sync pattern is reproduced in the cycle of 1.2ms. DVD sync detector 521 detects the DVD frame sync signal, and outputs it to controller 511. Controller 511 sets the DVD mode as its initial mode if the disk is detected to be mounted. When the constant linear velocity (CLV) servo of the DVD mode is ON, and if the disk mounted is a DVD where data and sync patterns are recorded as shown in Figure 10, controller 511 receives the DVD frame sync signal in the cycle of 1.2ms. When controller 511 sets the DVD mode as the initial operation mode, the DVD sync pattern can be detected normally in case that the disk mounted is DVD. However, if the CD is mounted while the DVD mode is set, the frame sync signal cannot be detected while the CLV servo is applied. In this embodiment, after the CLV servo is applied when the disk is mounted while the initial driving mode is DVD mode, it is determined whether the sync signal reproduced is detected or not, so as to decide whether the current mode is CD or DVD. According to the result decided, the CD or DVD reproducing mode is selectively driven. Figure 12 shows the procedure of selectively driving a corresponding playback mode by controller 511's detecting the kind of disk mounted according to the second embodiment. As shown in this figure, it is determined in this embodiment whether the DVD frame sync signal is detected or not, after the DVD mode is set as the initial playback mode when the disk is mounted. If the sync signal is detected according to the result, it is determined that the DVD is mounted so that the DVD reproducing system is selectively driven. If the sync signal is not detected for a predetermined time, it is determined that the CD disk is mounted so that the CD reproducing system is selectively driven. Referring to Figure 12, controller 511 checks whether any disk is mounted. First of all, controller 511 checks the state of input portion 510 to thereby find out the ON/OFF of the tray. If the tray is ON/OFF, controller 511 detects it in steps 1211 and 1213, and then decides that the disk is mounted. Thereafter, controller 511 controls a servo controller (not shown) in step 1215 so as to perform the optical pickup 111's focusing. Here, optical pickup 111 is a unit usable for both CD and DVD. Therefore, the servo controller drives optical pickup 111 as the CD pickup unit. Controller 511 raises or lowers the optical pickup 111's focusing in step 1215, and checks in step 1217 whether focus locking is performed. Here, if focus locking is not performed, controller 511 senses this situation in step 1217, and decides in step 1219 that the disk is not mounted. This case indicates that the tray is ON/OFF by a user while the disk is not mounted. If focus locking is performed in step 1217, this state indicates that the disk is mounted on the tray. In this case controller 511 controls the servo controller through steps 1221-1225 so as to rotate the disk mounted and turn on the tracking servo and CLV servo. Here, the servo controller drives the spindle motor under the control of controller 511 to thereby rotate the disk. In addition, the tracking servo is performed so that optical pickup 111 accurately traces the tracks. If the tracking servo is finished, the rotation speed of disk is controlled by manipulating the spindle motor in the CLV mode of the DVD playback mode. This situation shows that the CLV mode of the DVD playback mode is set during disk mounting and the detection of DVD frame sync signal is prepared. If the DVD CLV servo is ON, controller 511 receives the output of DVD sync detector 522 in step 1227, and checks whether the DVD frame sync signal is detected or not. Here, DVD sync detector 522 receives the data stream filtered and equalized in the DVD band, and the data stream input is compared with the previously stored DVD frame sync pattern. Here, the DVD frame sync pattern commonly has the reference data stored in reference register 72, and is a peculiar pattern (14T) having a format different from the data recorded in the DVD. DVD sync detector 522 compares the sync pattern with the data stream received so that the pattern having the same value is output as the DVD frame sync signal. If the disk mounted is DVD, the sync signal output from DVD sync detector 522 is generated in the cycle of 1.2ms, as in Figure 11c. Controller 511 senses in step 1227 that the DVD frame sync signal is detected. The sync signal is detected until a predetermined number through steps 1229 and 1231. The number of detection of the DVD frame sync signal is set to be many enough to decide that the disk mounted is DVD. For example, herein, if this number is set to be three, then once the signal has been detected three times, it can confidently be decided that the disk is a DVD. If the DVD frame sync signal is detected as many as the predetermined number, controller 511 establishes optical pickup 111 as being for DVD in step 1233, and resets the CLV servo for DVD playback. Then, in step 1235 DVD signal processor 517 and A/V decoder 518 are controlled to thereby activate the DVD playback system, and CD signal processor 514 and audio processor 515 are controlled to thereby inactivate the CD playback system. By doing so, the DVD playback mode is performed. However, if the DVD frame sync signal is not detected in step 1227, controller 511 checks in step 1237 whether the predetermined time passes. This means that the detection of the DVD frame sync signal is performed for the predetermined time even when the disk mounted is CD. Controller 511 waits to detect the DVD frame sync signal for the predetermined time after the DVD CLV servo is ON. If the sync signal is not detected for this time, the disk mounted is decided to be CD. The predetermined time is a period in which several DVD frame sync signals can be detected. If the DVD frame sync signal is not received for the predetermined time, controller 511 decides in step 1239 that the disk mounted is CD. In step 1241 optical pickup 111 is set for CD, and the CD CLV servo is ON. If the CLV is locked thereafter, controller 511 senses it in step 1243, and in step 1245 CD signal processor 514 and audio processor 515 are ON to activate the operation of the CD playback system. The DVD signal processor 517 and A/V decoder 518 are inactivated to drive the DVD playback system and perform the CD playback mode. In the second embodiment described as above, the DVD playback mode is first performed when the disk is mounted in a disk playback system for reproducing both CD and DVD, to thereby check whether there is a DVD frame sync signal of the disk. If the DVD frame sync signal is detected, the disk mounted is detected to be DVD, and the DVD playback system is activated to perform the DVD playback mode. If not, the disk mounted is decided to be CD, and the CD playback system is activated to perform the CD playback mode. Third Embodiment Figure 13 shows a configuration of automatically detecting the kind of disks mounted in the third embodiment of disk recording/reproducing system having CD and DVD reproducing systems. It is assumed that optical pickup 111 uses CD/DVD optical pickup unit. Radio frequency (RF) receiver 512 amplifies a weak light signal reproduced from optical pickup 111. Here, the RF signal output from RF receiver 512 is a signal reproduced from the CD or DVD. First, in the CD reproducing system, CD equalizer 513 filters the CD band of the RF signal output from RF receiver 512, and equalizes it. CD signal processor 514 demodulates the data stream modulated and output from CD equalizer 513, and corrects errors produced during the above procedure. Audio processor 515 signal processes the data output from CD signal processor 514. Secondly, in the DVD reproducing system, DVD equalizer 516 filters the DVD band of the RF signal received, and equalizes it. Here, the DVD band becomes a wide band containing the CD band. DVD signal processor 517 receives the DVD band of data stream output from DVD equalizer 516 to thereby demodulate the data modulated, and correct errors produced during the above procedure. DVD signal processor 517 corresponds to demodulator/ECC corrector 113 shown in Figure 1. A/V decoder 518 splits the data output from DVD signal processor 517 into video data and audio data, and signal processes them. A/V decoder 518 corresponds to system decoder 116, video decoder 117 and audio decoder 119. This embodiment of the disk reproducing apparatus has CD and DVD reproducing systems. Optical pickup 111 is a unit capable of reproducing both CD and DVD. If a disk is mounted on the disk reproducing apparatus, it should be determined whether the disk mounted is CD or DVD, and then a corresponding reproducing system should be selectively driven. For this, CD sync detector 521 is built in CD signal processor 514, and DVD sync detector 522 is incorporated in DVD signal processor 517. Controller 511 decides the kind of the disk mounted and selectively drives a corresponding reproducing system, depending upon whether the CD or DVD frame sync pattern output from CD or DVD sync detector 521 or 522 is detected or not. As explained above, CD and DVD have different frame sync patterns. For this reason, the disk reproducing system having CD and DVD playback systems can detect the kind of disk by checking the frame sync pattern recorded on the disk. Here, the CD frame sync pattern's characteristics are the same as those in the first embodiment of Figure 6. The DVD frame sync pattern's characteristics are the same as those in the second embodiment of Figures 10 and 11. The CD sync detector 521 for detecting the CD frame sync pattern and the DVD sync detector 522 for detecting the DVD frame sync pattern can be constructed as in Figure 7 according to the first and second embodiments. Here, reference register 72 of CD sync detector 521 stores the CD frame sync pattern shown as 6a of Figure 6. Reference register 72 of CD sync detector 522 stores the DVD frame sync pattern shown as 11a of Figure 11. If the disk mounted is sensed initially, controller 511 sets its initial driving mode as CD or DVD mode. Here, if controller 511 sets the initial driving mode as CD mode, the CD frame sync pattern can be detected normally in case that the disk mounted is CD. However, if the DVD is mounted while the CD mode is set, the frame sync signal cannot be detected while the CLV servo is applied. In this case, controller 511 converts the initial operating mode into the DVD mode so that the DVD frame sync signal can be detected by DVD sync detector 522. Reversely, if controller 511 sets the initial driving mode as DVD mode, the DVD frame sync pattern can be detected normally in case that the disk mounted is DVD. However, if the CD is mounted while the DVD mode is set, the frame sync signal cannot be detected while the CLV servo is applied. In this case, controller 511 converts the initial operating mode into the CD mode so that the CD frame sync signal can be detected by CD sync detector 521. In this third embodiment of the present invention, the initial operating mode is set as CD mode when the disk is mounted, and then it is checked whether the CD frame sync pattern is detected or not. If the pattern is detected, the CD playback mode is performed continuously. If not, then the current mode is converted into the DVD mode to detect the DVD frame sync pattern and then continuously perform the DVD playback mode. Figures 14a and 14b show the flowchart of the procedure of selectively driving a corresponding playback mode by controller 511's detecting the kind of disk when the disk is mounted, according to the third embodiment of the present invention. Referring to Figure 13, controller 511 detects the CD frame sync signal in the sequence of the first embodiment through steps 1411-1435 of Figure 14a. When the CD frame sync signal is detected, the CD playback system is selectively driven to perform the CD playback mode. First of all, if the disk is detected to be mounted, the CD playback mode is set as the initial driving mode and the output of CD sync detector 521 is analyzed. If the CD frame sync signal is detected, it is then determined that the disk mounted is CD, and the CD playback mode is performed. If the CD frame sync signal is not received for a predetermined time, for example, 100ms - 500ms, in the state in which the CD playback mode is set as the initial driving mode, controller 511 senses it in step 1437 of Figure 14a. Then, in step 1439 of Figure 14b, the current mode is converted into the DVD mode so that optical pickup 111 is controlled to reproduce information recorded on the DVD. Through steps 1449-1467, the DVD frame sync signal is detected and the DVD playback mode is performed, as in the second embodiment. In the third embodiment of the present invention, the CD playback mode is first performed to check whether the CD frame sync signal of the disk is detected or not, when the disk is mounted in the disk playback system capable of simultaneously reproducing CD and DVD. If the CD frame sync signal is not detected, the DVD frame sync signal is detected. In another aspect of the present invention, the DVD playback mode is first performed to check whether the DVD frame sync signal of the disk is detected or not. If the DVD frame sync signal is not detected, the CD frame sync signal can be detected. In this situation, if the DVD frame sync signal is detected, the disk mounted is detected to be DVD, and the DVD playback system is activated to perform the DVD playback mode. Here, if the DVD frame sync signal is not detected for a predetermined time, the DVD driving mode is converted into the CD mode, and then the CD frame sync signal is detected. By doing so, the disk mounted is determined to be CD, and the CD playback system is activated to perform the CD playback mode. In the first, second and third embodiments of the present invention, there has been explained a single pickup capable of reproducing both CD and DVD. However, the present invention can be applied equally to a disk playback system having CD-only pickup and DVD-only pickup separately. In this configuration, the data stream generated from the CD-only pickup is first analyzed when a disk is mounted, to thereby check whether the CD frame sync signal is detected or not. Here, if the CD frame sync signal is detected, the CD playback mode is performed. If the signal is not detected for a predetermined time, the DVD-only pickup is activated to select the DVD playback system and perform the DVD playback mode. As described above, the present invention is capable of automatically detecting the kind of disk inserted into an apparatus for reproducing multiple disks. Especially, the sync signal of the disk mounted is detected to decide the kind of disk so that the kind of disk can be accurately detected. According to the result detected, a corresponding disk playback mode is automatically performed. Therefore, it should be understood that the present invention is not limited to the particular embodiment disclosed herein as the best mode contemplated for carrying out the present invention, but rather that the present invention is not limited to the specific embodiments described in this specification except as defined in the appended claims.

Claims: An optical disk reproducing apparatus, characterised in that : the apparatus comprises playback systems of CD and DVD containing their respective sync signals, the CD and DVD playback systems (513-515; 516-518) respectively having sync detectors (521, 522), the systems analyzing a sync signal output from the sync detectors (521, 522) when a disk (20) is detected to be mounted, the CD playback system (513-515) being selectively driven when a CD sync signal is detected to perform a CD playback mode, the DVD playback system (516-518) being selectively driven when a DVD sync signal is detected to perform a DVD playback mode. The optical disk reproducing apparatus of claim 1, wherein the system CD playback system (513-515) is arranged to analyze whether a CD sync signal output from the CD sync detector (521) is detected or not when a disk (20) is detected to be mounted and be selectively driven when the CD sync signal is detected to perform a CD playback mode, and, the DVD playback system (516-518) is arranged to be selectively driven when the CD sync signal is not detected for a predetermined time to perform a DVD playback mode. The optical disk reproducing apparatus of claim 1, wherein the DVD playback system (516-518) is arranged to analyze whether a DVD sync signal output from the DVD sync detector (522) is detected or not when a disk (20) is detected to be mounted and be selectively driven when the DVD sync signal is detected to perform a DVD playback mode, and, the CD playback system (513-515) is arranged to be selectively driven when the DVD sync signal is not detected for a predetermined time to perform a CD playback mode. The optical disk reproducing apparatus of claim 1 or 2 further comprising an optical pickup (111) arranged to be controlled for CD-only reproduction as the playback systems (513-515, 516-518) analyze the sync signal output from the sync detectors (521, 522). The optical disk reproducing apparatus of claim 1 or 3 further comprising an optical pickup (111) arranged to be controlled for DVD-only reproduction as the playback systems (513-515, 516-518) analyze the sync signal output from the sync detectors (521, 522). The optical disk reproducing apparatus of any preceding claim comprising a double focus optical pickup (111).

Inventors: BYUN YOUNG-GI, KIM YOUNG-HAN, SONG MYOUNG-JONG, BYUN, YOUNG-GI, KIM, YOUNG HAN, SONG, MYOUNG-JONG
Applicants: SAMSUNG ELECTRONICS CO LTD, SAMSUNG ELECTRONICS CO., LTD.
Application year: 1997
Main classification: G11B19
IPC codes: G11B7, G11B20, G11B27, G11B19