KR100662593B1 - Optical disk apparatus and control method - Google Patents

Abstract

A reading unit 15 for reading out the reflected light from the optical disk D of the laser beam and outputting a read signal including the first S-shaped signal S1 and the second S-shaped signal S2; The first comparator 52 which detects the first S-shaped signal S1 by comparing with the first threshold TH1 + and the second threshold TH2 + by comparing the read signal with the second threshold TH2 + which is larger than the first threshold TH1 +. The second comparator 53 detects the S-shaped signal S2, and the second comparator 53 is the second comparator 53 when the first comparator 52 detects the first S-shaped signal S1. A timekeeping unit 57 for time period indicating the detection of the S-shaped signal S2 is provided.

Description

Optical disk device and its control method {OPTICAL DISK APPARATUS AND CONTROL METHOD}

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing an embodiment of the present invention for explaining an optical disk device.

Fig. 2 is a diagram showing a detailed configuration of the pickup of the optical disk apparatus in the embodiment.

FIG. 3 is a block diagram showing the details of an S-shaped signal detection circuit of the optical disk apparatus according to the embodiment; FIG.

Fig. 4 is a diagram for explaining the operation of the S-signal detection circuit of the optical disk apparatus in the embodiment.

Fig. 5 is a timing chart shown for explaining the operation of the S-shaped signal detection circuit of the optical disk device in the embodiment.

Fig. 6 is a timing chart showing the undetected operation of the S-shaped signal detection circuit of the optical disk device in the embodiment.

Fig. 7 is a timing chart showing the reciprocating operation of the S-shaped signal detection circuit of the optical disk apparatus in the embodiment.

FIG. 8 is a timing diagram illustrating another example of the detection signal detected by the S-signal detection circuit of the optical disk apparatus according to the embodiment; FIG.

<Explanation of symbols for main parts of drawing>

D: optical disc

12: RF amplifier

13: rotary motor

14: motor control circuit

15: pickup

16: PLL circuit

17: error correction circuit

35: S-signal detection circuit

36: wobble PLL section / address detection section

37: focusing circuit

38: tracking control unit

40: CPU

41: RAM

42: ROM

43: interface circuit

44: host device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus and a control method thereof, and more particularly to detecting an S-shaped signal from a read signal of the optical disk to determine the type of the optical disk.

As is well known, a plurality of types of optical discs, such as a recording type, a reproduction-only DVD (Digital Versatile Disc), or a conventional type CD (Compact Disc), have recently become popular as recording media for digital data. In the optical disk device that reproduces these optical disks, high reliability is required. Further, in such an optical disk apparatus, a plurality of types of optical disks must be supported, and the type of optical disk must be identified.

Japanese Patent Application Laid-Open No. 10-188458 discloses a reflected light beam obtained by condensing a light beam on a disk, and estimates the thickness of the protective layer based on the generation interval of the first and second reflected light intensities or the focus error signal. The optical disk device for determining the type of disk is shown.

However, the technique of Japanese Unexamined Patent Application Publication No. 10-188458 described above sets the measurement start when the level is out of zero level and the measurement end when the level reaches O level. Therefore, a false measurement is performed when noise is affected. In addition, when one threshold value is provided to measure signals having different amplitudes, there is a problem that the measurement is performed without detecting the correct amplitude.

Moreover, in the technique of this Japanese Patent Laid-Open No. 10-188458, when the rise exceeding the threshold value is detected by the first S-shaped signal S1 of the S-shaped signal, the time until the next detected rise is measured. Although the thickness of the protective layer of the optical disk is estimated by this, when the rise of the 1st S-shaped signal S1 is lost by noise etc., a fall is made into a measurement start position. As a result, there is a problem that the measuring counter may runaway because the fall of the first S-shaped signal S1 and the rise of the second S-shaped signal S2 are mistaken for one S-shaped signal.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to identify plural kinds of S-shaped signals included in the read signal of the optical disc by different thresholds and to discriminate the type of the optical disc. It is to provide an optical disk device having a performance and a control method thereof.

According to one embodiment of the present invention, there is provided an optical disk apparatus, comprising: a reading unit for reading reflected light from an optical disk of laser light and outputting a read signal including a first S-shaped signal and a second S-shaped signal; A first comparator that detects the first S-shaped signal by comparing the first to a threshold, a second comparator that detects the second S-shaped by comparing the read signal with a second threshold greater than the first threshold; There is provided an optical disk apparatus including a timekeeping section that time periods from when the first comparator detects the first S-shaped signal to when the second comparator detects the second S-shaped signal.

According to another embodiment of the present invention, there is provided a control method of an optical disk apparatus that reads reflected light from an optical disk of laser light and outputs a read signal including a first S-shaped signal and a second S-shaped signal, A first step of detecting the first S-shaped signal by comparing with the first threshold value, a second step of detecting the second S-shaped signal by comparing the read signal with a second threshold larger than the first threshold, and in the first step There is provided a control method of an optical disk apparatus, comprising a third step of time-limiting a period from when the first S-shaped signal is detected to when the second S-shaped signal is detected in the second step.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the embodiment described below, an S-shaped signal detection circuit for detecting a plurality of S-shaped signals included in the read signal is shown, and the output of the S-shaped signal detecting circuit is used for the determination of the type of optical disc. It is not limited, for example, It is suitable also for using auxiliary to a focusing control part.

1 is a block diagram showing an optical disk device according to the present embodiment, FIG. 2 shows a detailed configuration of a pickup of the optical disk device, and FIG. 3 shows an S-shaped signal detection circuit of the optical disk device. It is a block diagram.

<Optical disk device according to the present embodiment>

(Configuration and operation)

The optical disk apparatus according to the present embodiment is configured as shown in FIG. Here, the optical disk D is an optical disk capable of recording user data or an optical disk dedicated to reading, but this embodiment will be described as a recordable optical disk. As recordable optical discs, there are optical discs such as DVD-R, DVD-RAM, CD-R, and CD-RW.

On the surface of the optical disc D, land tracks and groove tracks are formed spirally. This optical disk D is rotationally driven by the spindle motor 13. The recording and reproducing of the information on the optical disc D are performed by the pickup 15.

The pickup 15 is provided with an objective lens 22 as shown in FIG. The objective lens 22 can be moved in the focusing direction (optical axis direction of the lens) by driving the drive coil 21. In addition, the objective lens 22 can be moved in the tracking direction (the direction orthogonal to the optical axis of the lens) by the drive of the drive coil 20, and the tracking control can be performed by moving the beam spot of the laser beam.

The semiconductor laser diode 28 generates laser light in accordance with a signal supplied from a laser control circuit (not shown). The laser light generated from the semiconductor laser diode 28 is irradiated onto the optical disk D through the collimator lens 25, the half prism 24, the optical system 23, and the objective lens 22. The reflected light from the optical disk D is guided to the photodetector 26 through the objective lens 22, the optical system 23, the half prism 24 and the condenser lens 27.

The photodetector 26 consists of four divisions of photodetection cells, and supplies detection signals A, B, C, and D to the RF amplifier 12. The RF amplifier 12 supplies the tracking error signal TE, which is (A + C)-(B + D), to the tracking control unit 38 according to the DPD method of the DVD ROM.

In addition, according to the astigmatism method, the RF amplifier 12 has an S-shaped signal detection circuit having a focus error control signal FE of (A + D)-(B + C) and a plurality of thresholds with the focusing control part 37 ( 35) to supply.

In addition, the RF amplifier 12 supplies the wobble signal WB, which is (A + B)-(C + D), to the wobble PLL section / address detection section 36, and (A + B) + (C + D). Is supplied to the data reproducing section 34.

On the other hand, the focus control signal output from the focusing control section 37 is supplied to the focusing driving coil 21. As a result, control is made such that the laser light always becomes just focus on the recording film of the optical disc D. FIG. The tracking control unit 38 also generates a tracking control signal and supplies it to the drive coil 20 in the tracking direction.

By the focusing control and the tracking control, the sum signal RF of the output signal of the photodetector cell of the photodetector 26 changes the reflectance from the pit or the like formed on the track of the optical disc D in response to the recording information. Is reflected. This signal is supplied to the data reproducing section 34.

The data reproducing section 34 reproduces the recording data based on the reproducing clock signal from the PLL circuit 16, and further error correction is performed by the error correction circuit 17 to reproduce the reproducing signal via the interface 43 circuit. Is supplied to the host device 44, for example. In addition, the data reproducing section 34 has a function of measuring the amplitude of the signal RF, and the measurement is read by the CPU 40.

The motor control circuit 14, the PLL circuit 16, the data reproducing section 34, the focusing control section 37, the tracking control section 38, and the like can be configured in one LSI chip as a servo control circuit. These circuits are also controlled by the CPU 40 via the bus 39.

The CPU 40 comprehensively controls this optical disk device in accordance with an operation command provided from the host device 44 via the interface circuit 43. In addition, the CPU 40 uses the RAM 41 as a work area and performs a predetermined operation in accordance with a program recorded in the ROM 42.

In addition, the S-shaped signal detection circuit 35 according to the present embodiment has comparators 52 and 53 which receive the focus error signal FE supplied from the RF amplifier 12, as shown in FIG. The comparator 52 is provided with a first threshold value TH1 + and a first threshold value TH1- from the outside (or CPU). Similarly, the comparator 53 has a second threshold value TH2 + and a second threshold value TH2. -) Is given from the outside (or CPU).

In addition, the output from the direction detector 51 which receives the focus error signal FE from the CPU 40 or the focusing 37 control unit is provided with the comparators 52 and 53, the counter 57 and the averaging circuit 58 described later. ) Is supplied.

In addition, the S-shaped signal detection circuit 35 according to the present embodiment has phase detection sections 54 and 55 that receive the outputs of the comparators 52 and 53, respectively, and phases that receive the output of the phase detection sections 54 and 55. A counter 57 for receiving the outputs of the correction unit 56, the phase correction unit 56 and the phase detection unit 55 from the input terminal, and counting the period of the signal; and an averaging circuit receiving the output of the counter 57 ( 58).

<Operation of S-Signal Detection Circuit According to the Present Embodiment>

Next, the processing operation of the S-signal detection circuit 35 according to the present embodiment will be described in detail below with reference to the drawings. 4 is a view for explaining the operation of the S-signal detection circuit 35 of the optical disk device according to the present embodiment, and FIG. 5 is a timing diagram for explaining the operation of the S-signal detection circuit 35 for the optical disk device. FIG. 6 is a timing diagram illustrating an undetected operation of the S-signal detection circuit 35 of the copper optical disk device, and FIG. 7 illustrates a reciprocating operation of the S-signal detection circuit 35 of the copper optical disk device. 8 is a timing diagram illustrating another example of the detection signal detected by the S-shaped signal detection circuit 35 of the copper optical disk apparatus.

(Optical disc type determination by S-signal detection circuit)

First, the type determination process of the optical disc D by detecting the S-shaped signal will be described with reference to FIG. 4. The S-shaped signal detection circuit 35 according to the present embodiment is not necessarily to be used for optical disc type determination. As a preferred embodiment, the type of optical disc can be determined using the detection signal of the S-shaped signal.

That is, in Fig. 4, the period T1 is a state in which the laser light irradiated from the objective lens 22 is separated from the optical disk D. In the period T2, the laser light is focused on the surface F of the optical disk D. The state, period T3 represents the state in which the laser light is focused on the transparent substrate in the optical disk D, and the period T4 represents the state in which the laser light is focused on the recording layer R, respectively.

In addition, when the optical disk D is irradiated with a light beam and the focus error signal FE obtained from the pickup 15 includes two S-shaped signals S1 and S2, the first S-shaped signal ( S1 is a detection signal of the surface F of the optical disk D, and the second S-shaped signal S2 is a detection signal of the recording layer R of the optical disk D. FIG.

S-shaped on the surface F of the optical disc D by comparing the first S-shaped signal S1 with the first threshold values TH1 +, TH1- in response to the arrival of the first S-shaped signal S1. Signal detection can be performed. Next, when the second S-shaped signal S2 is reached, the second S-shaped signal S2 and the second thresholds TH2 + and TH2- are compared to the recording layer R of the optical disk D. FIG. S-shaped signal detection can be performed. In addition, by accurately measuring between the first S-shaped signal S1 and the second S-shaped signal S2, the distance from the surface F of the optical disk D to the recording layer R can be measured. .

The disc type can be accurately determined by determining the type of the optical disc D by these three processes. The calculation of the distance from the surface F of the optical disk D to the recording layer R is preferably performed by the CPU 40 or the like receiving the signal given from the averaging circuit 58.

Here, the distance from the surface F of the optical disk D to the recording layer R is determined as a standard by the type of the optical disk D. Therefore, by measuring the period t1 from the start of generation of the first S-shaped signal S1 to the start of generation of the second S-shaped signal S2 and comparing it with a predetermined value, the optical disk D is, for example, a DVD. (Digital Versatile Disc) or CD can be determined.

These operations will be described below using the configuration of the S-signal detection circuit 35 in FIG. 3.

The comparator 52 performs a comparison process between the focus error signal FE including the S-shaped signal and the first thresholds TH1 + and TH1-. Here, when the input focus error signal FE (S-shaped signal) passes the threshold, the comparison result is output to the phase detection unit 54.

The threshold value includes the first threshold value TH1 + for rising detection and the first threshold value TH1- for falling detection, and the S-shaped signal S1 can be measured even from the rising or the falling. The threshold uses two's complement. The phase detector 54 detects whether the S-shaped signal S1 has been input from the rising or falling, and indicates one cycle of the amplitude signal that has passed through the first threshold.

In addition, the comparator 53 compares the focus error signal FE including the second S-shaped signal S2 with the second thresholds TH2 + and TH2-. Here, when the input second S-shaped signal S2 passes the second thresholds TH2 + and TH2-, the comparison result is output to the phase detection unit 55. The threshold value has a second threshold value TH2 + for rising detection and a second threshold value TH2- for falling detection, so that the S-shaped signal can be measured from rising to falling. The threshold uses two's complement.

The phase detection unit 55 detects whether the S-shaped signal was input from rising or falling, and indicates one cycle of the amplitude signal passing through the second thresholds TH2 + and TH2-.

The counter 57 counts the interval between the first S-shaped signal S1 and the second S-shaped signal S2. When a path is detected by the direction detector 51, time counting by the counter 57 is started in accordance with a signal from the phase correction unit 56 according to the result detected by the comparator 52. FIG.

The counter 57 continues to count until it passes one cycle of the amplitude signal detected by the phase detector 54, and the counter is counted by the signal from the phase detector 55 according to the result detected by the comparator 53. The count of 57 ends. The next count of the counter 57 is not started until one cycle of the S-shaped signal S2 detected by the phase detection unit 55 passes.

When a return path is detected by the direction detector 51, the count starts from the result detected by the comparator 53. The counting continues until one cycle of the amplitude signal detected by the phase detection unit 55 passes, and the counting ends from the result detected by the comparator 52. The next count does not start until one cycle of the amplitude signal detected by the phase detector 54 passes.

In addition, as will be described in detail later, the phase correction unit 56 starts counting the counter 57 in place of falling detection when the rising detection of the first S-shaped signal S1 fails. . Thus, even when there is a defect in the detection of the S-shaped signal, it is possible to quickly and reliably determine the type of the optical disk D. In addition, the direction detector 51 detects whether the S-shaped signal is the return path or the return path.

In addition, when the averaging circuit 58 performs the measurement between the S-shaped signals in a round trip, the averaging result can be averaged. When averaging is performed, the measurement result is output to the rear end once immediately after the measurement of the return path, and the measurement results of the return path and the return path are averaged immediately after the measurement of the return path. Averaging may not be performed. In this case, the results are output immediately after the measurement for both the return path and the return path. In addition, in the case of measuring only by a path | route, a measurement result is output immediately after a measurement.

Next, each signal in the operation by the S-shaped signal detection circuit 35 is shown in FIG. 5. That is, the timing signal T5 is a range from a position where the first S-shaped signal S1 of the phase detection unit 54 exceeds the first threshold value TH1 + to a position exceeding the first threshold value TH1-, One period according to the first threshold values TH1 + and TH1- of the first S-shaped signal S1 is shown. During this time, the counter 57 cannot be terminated. This is to suppress erroneous measurement caused by noise or the like.

Next, the count signal T6 indicates the count state from the first S-shaped signal S1 to the second S-shaped signal S2. When the comparator 52 detects that the first S-shaped signal S1 has exceeded the first threshold TH1 +, the counter 57 starts counting. In addition, when the comparator 53 detects that the second S-shaped signal S2 exceeds the second threshold value TH2 +, the counter 57 ends the counting.

In addition, the timing signal T7 is a range from a position where the second S-shaped signal S2 of the phase detection unit 54 exceeds the first threshold value TH1 + to a position where the first threshold value TH1 is exceeded. One cycle according to the first threshold values TH1 + and TH1- of the second S-shaped signal S2 is shown.

The timing signal T8 is a range from a position where the second S-shaped signal S2 of the phase detection unit 55 exceeds the second threshold value TH2 + to a position exceeding the second threshold value TH2−. One cycle by the second thresholds TH2 + and TH2- of the S-shaped signal S2 is shown. During this time, the counter 57 cannot be counted again. This is to suppress erroneous measurement caused by noise or the like. The count signal T9 is the final value counted by the counter 57. The output value of the counter 57 is output immediately after the end of the measurement.

Next, the output value of the counter 57 is averaged by the averaging circuit 58 in the case of round trip, and is supplied to the CPU 40 or the like via the data bus 39 via the averaging circuit 58 as it is in case of no round trip. do. The CPU 40 determines the type of the optical disk D by estimating the distance from the surface F of the optical disk D to the recording layer R based on the size of the given counter value.

The detection results of the S-shaped signals S1 and S2 of the S-shaped signal detecting circuit 35 are not limited to those used for the type discrimination of the optical disk D. For example, the S-shaped signal detecting circuit 35 supplies the beams to the focusing control section 37 to supply the beams. It is also suitable to use for focusing control of light.

(Defect processing of S-signal detection circuit)

Next, the defect processing of the S-shaped signal detection circuit 35 will be described. That is, since the focus error signal FE cannot be obtained correctly, the S-shaped signal S1 (or S2) may be misrecognized as shown in FIG.

In this case, by using the phase correction unit 56 of FIG. 3, by sending the corrected approximation signal to the counter 57, the failure of the measurement of the first half S1 ′ of the S-shaped signal can be recovered. The repetition can be prevented and the determination time of the optical disc type can be shortened.

That is, as shown in FIG. 6, when the rising S1 ′ of the first S-shaped signal S1 is not detected, the timing signal T11 is the first S-shaped signal S1 of the S-shaped signal. The rise cannot be detected due to the influence of noise or the like, and is output as a waveform of only the fall.

When the signal waveform T11 is identified, the phase correction unit 56 supplies the correction signal H to the input terminal of the counter 57 instead. As a result, the counter 57 starts counting in accordance with the rise of the correction signal H (T12), and finishes counting by the timing signal T13.

The timing signal T12 indicates the count state from the first S-shaped signal S1 to the second S-shaped signal S2. When the comparator 52 detects that the S-signal has exceeded the first threshold TH1-the counter 57 starts counting. When the comparator 53 detects that the S-shaped signal exceeds the second threshold TH2 +, the counter 57 ends the count.

The timing signal T13 indicates that the second S-shaped signal S2 is started from the rise by the phase detection unit 55, and notifies the phase correction unit 56 of the phase correction. As a result, the phase detected by the phase detection unit 54 is corrected, and the timing signal T11 that has been operated so as not to terminate the count 57 is replaced by the correction signal H, so that the runaway of the counter C is suppressed. . Incidentally, the timing signal T14 is the final value counted by the counter 57. The output value of the counter is output immediately after the end of the measurement.

In addition, in FIG. 5, when the fall of the 1st S-shaped signal S1 was not detected, it detects the phase of the 2nd S-shaped signal S2 by the phase detection part 55 similarly to the method shown in FIG. It is suitable to perform phase correction by this.

As a result, congestion of the counter 57 which is considered to occur when the rising or falling of the first S-shaped signal S1 is not detected can be prevented, and by supplying an appropriate counter value to the CPU 40 or the like, Even if there is a defect, the type of the optical disc D can be determined.

(Round trip measurement of S-signal detection circuit)

In addition, according to the S-time signal determination circuit 35 according to the present embodiment, even when the acquisition of the focus error signal FE is incomplete, as shown in FIG. 7, the focus position of the laser beam of the pickup 15 is set as follows. For example, by controlling the CPU 40 and the focusing control unit 37 to approach the optical disk D and away from it, the S-shaped signal can be measured in a round trip to further improve the determination accuracy of the optical disk type.

7, the first S-shaped signal S1 of the return path, the second S-shaped signal S2 of the return path, the second S-shaped signal S3 of the return path, and the first S-shaped signal S4 of the return path. Is included in the read signal and detected.

In contrast, the timing signal T21 ranges from a position where the first S-shaped signal S1 of the phase detection unit 54 exceeds the first threshold value TH1 + to a position where the first threshold value TH1 is exceeded. And one cycle by the first threshold of the first S-shaped signal S1. During this time, the counter 57 cannot be terminated. This is to suppress erroneous measurement caused by noise or the like.

The count signal T22 represents the count state from the first S-shaped signal S1 to the second S-shaped signal S2 of the S-shaped signal in the path. When the comparator 52 detects that the S-shaped signal exceeds the first threshold TH1 +, the counter 57 starts counting. When the comparator 53 detects that the S-shaped signal exceeds the second threshold TH2 +, the counter 57 ends the count.

The timing signal T23 represents a range from a position where the second S-shaped signal S2 of the phase detection unit 55 exceeds the second threshold TH2 + to a position exceeding the second threshold TH2-, One cycle based on the second threshold of the second S-shaped signal S2 is shown. During this time, the counter 57 cannot be counted again. This is to suppress erroneous measurement caused by noise.

The count signal T24 is the final value of the path counted by the counter 57. The output value of the counter 57 is output immediately after the measurement is finished. In addition, the timing signal T25 has shown the direction detected by the direction detector 51.

In addition, the second S-shaped signal S3 and the first S-shaped signal S4 in the return path are displayed. Because it is a return path, it becomes a waveform in contrast to a path.

The timing signal T26 represents a range from a position where the second S-shaped signal S3 of the phase detection unit 55 exceeds the second threshold TH2- to a position exceeding the second threshold TH2 +, One cycle based on the second threshold of the second S-shaped signal S3 is shown. During this time, the counter 57 cannot be terminated. This is to suppress erroneous measurement caused by noise or the like.

The count signal T27 represents the count state from the second S-shaped signal S3 of the S-shaped signal to the first S-shaped signal S4 in the return path. When the comparator 53 detects that the S-shaped signal exceeds the second threshold TH2-, the counter 57 starts counting. When the comparator 52 detects that the S-signal has exceeded the first threshold TH1-, the counter 57 ends the count.

The timing signal T28 represents a range from a position where the first S-shaped signal S4 of the phase detection unit 54 exceeds the first threshold TH1 to a position exceeding the first threshold TH1 +, 1 cycle by the 1st threshold value of 1st S-shaped signal S4 is shown. During this time, the counter 57 cannot be counted again. This is to suppress the error measurement due to noise.

The output of the timing signal T29 is a value obtained by averaging by the averaging circuit 58 the final value of the return or the final value and the final value of the return path counted by the counter 57. The output value or average value of the counter 57 is output immediately after the end of the measurement.

According to the S-shaped signal detection circuit 35 according to the present embodiment, by sequentially detecting the S-shaped signals S1, S2, S3, and S4 in the round trip in this order, the accuracy is further increased than in the case of detecting from one side. By detecting the S-shaped signal at a high level and detecting the distance between the signals at a high precision, the type of optical disc can be determined with high accuracy.

(Measurement processing of reverse phase S-shaped signal of S-signal detection circuit)

In addition, as shown in FIG. 8, the S-signal detection circuit 35 according to the present embodiment uses, as an example, the threshold TH1 having the same absolute value with the opposite sign as the first threshold value TH1 +. Comparator 52 for detecting the first S-shaped signal S1R having a phase displaced in the minus direction in the plus direction, and as an example, the threshold TH2- having the same absolute value as a sign opposite to the second threshold TH2 +. Has a comparator 53 for detecting the second S-shaped signal S2R having a phase shifting in the negative direction from the negative direction.

In other words, the reverse phase S-shaped signal as shown in Fig. 8 can also be reliably identified by preparing threshold values, respectively. Also in this case, the type of optical disc is determined in the same manner as obtained in the above-described period t1 based on the period t2 from the detection of the first S-shaped signal in the reverse phase to the detection of the second S-shaped signal in the reverse phase. It is possible to determine. This makes it possible to reliably and quickly determine the type even when the signal is reversely rotated due to a malfunction or noise or a special optical disk on which the signal is reversely rotated.

In addition, this invention is not limited to the above-mentioned embodiment as it is, In the implementation stage, a various deformation | transformation of a component can be embodied in the range which does not deviate from the summary. Moreover, various inventions can be formed by combining suitably the several component disclosed by the said Example. For example, some components may be deleted from all the components displayed in the embodiment. In addition, the components according to the other embodiments may be appropriately combined.

The optical disk device and its control method of the present invention have a high noise resistance identification performance by discriminating a plurality of types of S-shaped signals included in the read signal of the optical disk with different thresholds to determine the type of optical disk.

Claims (15)

As an optical disk device, A reading unit 15 which reads the reflected light from the optical disk D of the laser beam and outputs a read signal including the first S-shaped signal S1 and the second S-shaped signal S2; A first comparator 52 for detecting the first S-shaped signal S1 by comparing the read signal with a first threshold value TH1 +; A second comparator 53 for detecting the second S-shaped signal S2 by comparing the read signal with a second threshold TH2 + that is greater than the first threshold TH1 +; The period from when the first comparator 52 detects the first S-shaped signal S1 to when the second comparator 53 detects the second S-shaped signal S2 is determined. A timekeeping unit 57 that reveals time, When the reading unit 15 fails to detect the first S-shaped signal S1 using the first threshold TH1 +, a third threshold value TH1 different from the first threshold value TH1 + is used. Third comparison unit 56 for detecting the first S-shaped signal S1 Optical disk device comprising a. The method of claim 1, wherein the first S-shaped signal (S1) is a detection signal of the surface (F) of the optical disk (D), The second S-shaped signal S2 is a detection signal of the recording layer R of the optical disk D, The period in which the timepiece 57 is displayed is almost proportional to the distance from the surface F to the recording layer R, And a determination unit (40) for determining the type of said optical disc (D) in accordance with said period and outputting a determination result. The determining unit 40 according to claim 1, further comprising: a determination unit 40 which compares the time period displayed by the time display unit 57 with a predetermined value and determines the type of the optical disc D as a digital versatile disc (DVD) according to the determination result. It is provided with an optical disk device. An optical disc apparatus according to claim 1, wherein said timekeeping section (57) comprises a counter section (57) for time-keeping. delete 4. The fourth threshold value according to claim 1, wherein when the reading unit 15 fails to detect the second S-shaped signal S2 using the second threshold TH2 +, the fourth threshold is different from the second threshold TH2 +. And a fourth comparator (56) for detecting the second S-shaped signal (S2) using (TH2-). 2. The first S-shaped signal S1 of the return path and the second path of the return path according to claim 1, wherein the focus of the reading section 15 is closer to the optical disk D and then farther away. The first comparator 52 and the second comparator respectively display signals in the order of the S-shaped signal S2, the second S-shaped signal S3 of the return path, and the first S-shaped signal S4 of the return path. The period from the time when the 1st S-shaped signal S1 of the said path is detected by the comparator 53, and until the 2nd S-shaped signal S2 of the said path is detected, Further comprising a control unit 40 for causing the timekeeping unit 57 to time a period from when the S-shaped signal S3 is detected to when the first S-shaped signal S4 of the return path is detected. Optical disk device. 4. The fourth method of claim 1, wherein the first S-shaped signal S1 having a phase shifted from the negative direction to the positive direction by using a third threshold value TH1 that is different from the first threshold value TH1 + is detected. An optical disk apparatus further comprising a comparison unit (52). The fifth method of claim 1, wherein the second S-shaped signal S2 having a phase shifted from the negative direction to the positive direction by using a fourth threshold value TH2 that is different from the second threshold value TH2 + is detected. An optical disk apparatus further comprising a comparison unit (53). 4. The fourth method of claim 1, wherein the first S-shaped signal S1 having a phase shifted from the negative direction to the positive direction by using a third threshold value TH1 that is different from the first threshold value TH1 + is detected. Comparator 52, A fifth comparator 53 which detects the second S-shaped signal S2 having a phase shifted in a minus direction from a minus direction by using a fourth threshold value TH2- different from the second threshold value TH2 +; , The period from when the fourth comparator 52 detects the first S-shaped signal Sl until the fifth comparator 53 detects the second S-shaped signal S2 is determined. The second revelation unit 57 to reveal, And a second judging section (40) for judging the type of said optical disc (D) and outputting a determination result on the basis of the period of time which said second timing section (57) displays. A control method of an optical disk apparatus that reads reflected light from an optical disk D of a laser beam and outputs a read signal including the first S-shaped signal S1 and the second S-shaped signal S2, A first step 52 of detecting the first S-shaped signal S1 by comparing the read signal with a first threshold value TH1 +, A second step 53 of detecting the second S-shaped signal S2 by comparing the read signal with a second threshold TH2 + that is greater than the first threshold TH1 +; Time period from when the first S-shaped signal S1 is detected in the first step 52 to when the second S-shaped signal S2 is detected in the second step 53 is counted. Third process 57 to perform, When the detection of the first S-shaped signal S1 using the first threshold value TH1 + fails, the first S-shaped signal (using the third threshold value TH1- different from the first threshold value TH1 + may be used. Fourth Step 56 of Detecting Sl) The control method of the optical disk device provided with. The method of claim 11, wherein the first S-shaped signal (S1) is a detection signal of the surface (F) of the optical disk (D), The second S-shaped signal S2 is a detection signal of the recording layer R of the optical disk D, The period of time counted in the third process 57 is substantially proportional to the distance from the surface F to the recording layer R, And a fifth step (40) of determining the type of said optical disc (D) in accordance with said period and outputting a determination result. delete 12. The method of claim 11, wherein when the detection of the second S-shaped signal S2 using the second threshold TH2 + fails, a fourth threshold value TH2- different from the second threshold value TH2 + is used. And a fifth step (56) of detecting the second S-shaped signal (S2). 12. The first S-shaped signal S1 of the return path and the first path of the return path according to claim 11, wherein the focus of the optical disk D is closer to the optical disk D and then farther away. 2 S-shaped signal S2, a second S-shaped signal S3 of the return path, and a first S-shaped signal of the first S-signal S4 of the return are respectively detected, and the first S-shaped of the path is detected. The period from when the signal S1 is detected to when the second S-shaped signal S2 of the return path is detected, and when the second S-shaped signal S3 of the return path is detected, the first of the return paths. And a fifth step (40) which causes each of the time periods until the S-shaped signal (S4) is detected to be detected.

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