JP2000100064A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit rapid recovery even through the error is generated in the course of reproduction by calculating the number of address period signals per one round of an optical disk at the present light spot position in the manner of using the reciprocal of the product of the time interval between the detected address period signals and the number of rotation of the optical disk. SOLUTION: By a CPU 24, the number of pulses from a circuit 25 for detecting the number of motor rotation is counted simultaneously with the reading of the counted value held by a latch 23, and the number of disk rotation is obtained to calculate the specified formula. The address is detected in such a manner that an optical disk rotating means is controlled by the number of disk rotation of a zone obtained by the calculation to set the number of zones and the initial address to the optical disk device. Then, the time interval of the address period signals is detected, and since the reciprocal of the product of the number of optical disk rotation and the time interval of the address period signals is calculated and the number of address period signals per one round of the disk at the light spot position is calculated, the present zone is rapidly known even though the error is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus, and more particularly, to an optical disk apparatus in which an error occurs during reproduction of a recordable optical disk on which address information is intermittently recorded and an optical pickup flows. The present invention relates to an optical disk device capable of quickly calculating a position where a pickup has flown and recovering quickly to a reproduction state.

[0002]

2. Description of the Related Art In recent years, with the emergence of a digital versatile disk (Digital Versatile Disk, hereinafter referred to as "DVD"), a large-capacity optical disk device has begun to attract attention, and not only a read-only disk device but also a recordable optical disk (hereinafter, referred to as "DVD"). "DVD-RA
M ”. ) Is expected to be developed.

[0003] First, the configuration of the address information reproducing circuit Z in the DVD-RAM disk device will be described.

In FIG. 5, reference numerals 101 and 102 denote comparators, which binarize an address signal with respect to respective threshold values. An OR gate 104 adds the outputs of the comparators 101 and 102. 10
Reference numerals 3 and 105 denote retriggerable mono-multis, a function of receiving pulses from the comparators 101 and 102 and outputting a pulse for an appropriate time, and a function of outputting a pulse again from the time when a trigger input is received during pulse output. have. 106 and 109 are current sources;
8 is an analog switch. And these 106, 1
The charge pump circuit C is constituted by 07, 108 and 109. An analog switch 110 is opened and closed by an address gate signal.
In this case, the capacitor 111 is charged and discharged.

Reference numeral 112 denotes an inverter, which is a comparator 10
The comparator 101 inverts the threshold voltage of
As a threshold voltage. The operation of the address information reproducing circuit Z of the DVD-RAM disk device configured as described above will be briefly described. When the address signal is input to the comparators 101 and 102, the comparator 101 sets the threshold (−) as the threshold voltage, the comparator 102 sets the threshold (+) as the threshold voltage, and Valued.

Here, the threshold value (-) is a voltage obtained by inverting the threshold value (+) by the inverter 12 with reference to the reference voltage.
Is a voltage symmetric with respect to the reference voltage.

In FIG. 5, an upper address obtained by binarizing the reference voltage of the address signal by the comparator 102 is an upper address, and a lower address obtained by binarizing the lower side by the comparator 101 is an OR gate 104. To generate a binary address signal.

[0008] The binary address signal generated by the OR gate 104 becomes an input signal of the charge pump circuit C.

On the other hand, the lower address of the comparator 101 is input as a trigger signal to the retriggerable monomulti 103, and the retriggerable monomulti 103 outputs a lower address detection signal.

The upper address of the comparator 102 is input to a retriggerable monomulti 105 as a trigger signal, and the retriggerable monomulti 105 outputs an upper address detection signal.

The lower address detection signal and the upper address detection signal are added by an external circuit to form an address gate signal for identifying a header area, and this address gate signal is used as a gate signal of the analog switch 110.

When the address gate signal is "H", the analog switch 110 is driven by the aforementioned binary address signal.
Is in the “on” state, the binary address signal “H”
The discharge current flows from the charge pump circuit C to the capacitor 111 during the period, and the discharge current flows from the capacitor 111 to the charge pump circuit C during the “L” period of the binary address signal.

Since the address information reproducing circuit Z is configured to operate as described above, while the header area is being identified, that is, during the period of the header area, the capacitor 11 is not used.
1 is charged and discharged, and the threshold (-) and the threshold (+) are fed back so that the pulse duty of the binary address signal gated by the address gate signal is set to 50%. Therefore, the address detection accuracy is improved, and accurate binarization is enabled.

In this way, by reading the recorded data of the DVD-RAM, that is, the address, by the address information reproducing circuit Z, accurate reproduction of the DVD-RAM is enabled.

Then, the recording data of the DVD-RAM will be briefly described. According to the DVD-RAM standard,
The DVD-RAM is divided into a plurality of zones and the DVD-R
As many sectors as the number unique to each zone (here, “n”) are provided for each round of AM. The track has lands and grooves alternately formed for each rotation, and the polarity of the tracking error signal is inverted between the lands and the grooves.

The reversal of the polarity of the tracking error signal will be described with reference to FIG.
In the switching portion from the (m-1) th sector to the (m) th sector, the address of the (m) th sector behind the header portion becomes valid, and in the land, the (m + n-1) th sector to the (m + n) sector The address of the (m + n) -th sector before the header portion in the switching portion to the No. sector becomes valid. That is, the rear portion of the header portion is effective in the groove, and the front portion of the header portion is effective in the land. That is, the tracking error signal is inverted between the land and the groove.

That is, in order to cope with a tracking error that may occur during DVD-RAM reproduction, it is necessary to smoothly switch between lands and grooves by inverting the polarity of tracking control every rotation.

Next, a procedure for determining the land-groove switching point will be described. First, the system control microcomputer sets the initial address and the number of sectors of the zone to be currently reproduced by the optical pickup in the optical disk device. At the same time, the rotation speed of the disk is controlled to match the rotation speed specific to the zone.

Normally, this operation enables the optical disk device to read the address of the DVD-RAM, and the system control microcomputer checks whether the read address is included in the current zone.

If the read address is included in the current zone, the optical disk apparatus calculates the number of remaining sectors up to the land / groove switching point as an expected value. This calculation is performed every time the address is read normally. Then, in accordance with the expected value, a land / groove switching signal is output to the servo circuit to invert the polarity of the tracking control so that it is possible to cope with the inversion of the polarity of the tracking error signal. Usually, the expected value and the timing at which the optical pickup comes to the land / groove switching point are almost the same, so that the land / groove switching signal may be output according to the calculated expected value.

[0021]

However, according to the prior art, if an error occurs during the reproduction of the DVD-RAM and the optical pickup flows and the reproduction position shifts greatly, the optical disk apparatus will not be able to detect the position where the optical pickup has flowed. There is a disadvantage that the zone cannot be quickly recognized and the initial address and initial value of the zone cannot be set.

That is, since the DVD-RAM employs a constant linear velocity recording (hereinafter referred to as "ZCLV") system for each zone, the rotation speed of the disk is made to correspond to the rotation speed specific to the zone. It is indispensable for accurate address reading to be performed, but when the above error occurs, it is difficult to accurately control the number of rotations of the disk quickly. In this case, the initial address of the zone where the flow has occurred cannot be read accurately. If the address cannot be read out, the optical disk device cannot not only calculate the expected value of the land / groove switching point, but also output a switching signal at an incorrect point. Smooth switching is not possible, that is, land /
The state in which tracking is lost due to the failure of groove switching is repeated. Then, if such a state continues, in the worst case, it becomes impossible to reproduce, which is a problem.

The present invention has been made in view of such circumstances, and its purpose is to solve the problem that even if an error occurs during playback of a DVD-RAM and an optical pickup flows, and the playback position is greatly shifted. An object of the present invention is to provide an optical disk device that can quickly set an initial address and an initial value of a zone where an optical pickup has flowed to the optical disk device.

[0024]

According to an aspect of the present invention, there is provided an optical disk apparatus for holding an optical disk having address information intermittently recorded on an information recording surface. Holding means;
Optical disk rotating means for rotating the optical disk, laser light generating means for generating laser light, and light spot forming for forming a light spot by converging the laser light generated by the laser light generating means on the information recording surface of the optical disk Means, a photodetector for detecting the reflected light of the light spot, and an area of the photodetector obtained by dividing a positional shift amount between the light spot and the track center into four by a track direction axis and an axis perpendicular to the axis. A phase difference tracking error detecting means for detecting by comparing the addition results of the diagonal areas, and the positional deviation amount between the light spot and the track center is determined by a track direction axis and an axis perpendicular to the axis. Of the four divided photodetector regions, two regions parallel to the track direction A push-pull tracking error detection unit that detects by comparing the calculation results; a tracking control amount detection unit that obtains a tracking control amount according to the positional deviation amount; and the tracking of the light spot based on the tracking control amount. An optical disc device comprising: a tracking control means for controlling in a center direction; and an address detection means for extracting an address signal from a reproduction signal obtained from the reflected light of the light spot, wherein the phase difference tracking error detection means or the push-pull is provided. Comparison means for binarizing the output from the tracking error detection means with a predetermined threshold value, and time for measuring the time between output pulses of the binarization means and detecting the time interval between address period signals An interval detecting means, and an optical disk rotation speed for detecting the rotation speed of the optical disk Output means, and calculating means for calculating the number of the address period signals per one turn of the optical disk at the position of the light spot, wherein the calculating means detects the number of the optical disk rotation number detected by the optical disk rotation number detecting means. The reciprocal of the product of the number of rotations and the time interval between the address period signals detected by the time interval detection means is calculated, and the optical disc rotation is calculated in accordance with the number of the address period signals calculated by the calculation means. An optical disk rotation control means for controlling the means is provided.

According to a second aspect of the present invention, in the optical disk apparatus according to the first aspect, the calculating means calculates based on a rotation speed of the optical disk and a time interval between the address period signals. The calculation is performed by multiplying the reciprocal of the product of the address period signal and the time width of the address period signal by a known fixed coefficient.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiment shown here is merely an example, and is not necessarily limited to this embodiment.

(Embodiment 1) First, an example of an optical disk apparatus according to the present invention will be described as a first embodiment with reference to the drawings. FIG. 1 is a block diagram of an address information reproducing circuit X in the optical disk device according to the first embodiment.

In FIG. 1, reference numeral 1 denotes a photodetector for detecting light reflected from the information recording surface of the DVD-RAM. As shown in FIG. Is divided into two areas. Then, the four divided signals a to d are processed to detect a tracking error signal. Reference numerals 2 and 3 denote adders for adding signals of diagonally opposite regions of the photodetector 1 divided into four regions a to d in order to obtain a phase difference tracking error signal. The adder 3 adds the signal of the area c and the signal of the area b and the signal of the area d, respectively. Reference numeral 4 denotes a comparator for binarizing the output of the adder 2 with a predetermined threshold, and reference numeral 5 denotes a comparator for binarizing the output of the adder 3 with a predetermined threshold.

Reference numeral 6 denotes a phase comparator for comparing the phase of the pulse output from the comparator 4 with the phase of the pulse output from the comparator 5.
When the input pulse is ahead of the input pulse, the "+" output is
Is output from the terminal C when the input pulse of the terminal B is sent from the input pulse of the terminal B. 7 is a phase comparator 6
Is a low-pass filter for removing high-frequency components from the output signal of FIG. Normally, the cutoff frequency of the low-pass filter is set to several tens Khz, and the same applies to the present embodiment. Reference numerals 8 and 9 denote adders for adding signals in two regions parallel to the track direction of the photodetector 1 in order to obtain a push-pull tracking error signal. The adder 9 adds the signals of the area a and the area b, respectively.

Reference numeral 10 denotes a differential amplifier for calculating a push-pull signal, and reference numeral 11 denotes a low-pass filter for removing high-frequency components from the output signal of the differential amplifier 10.
Reference numeral 12 denotes a switch for switching between a phase difference tracking error signal and a push-pull tracking error signal by a switching signal. Reference numeral 13 denotes a comparator for binarizing the phase difference tracking error signal or the push-pull tracking error signal with a predetermined threshold. 14, 1
Flip-flops 5, 16, and 17 constitute a shift register S.

Reference numerals 18, 19 and 20 denote AND circuits for generating a timing signal using the signal of the shift register S. Reference numeral 21 denotes a set / reset circuit, which is set by the output of the AND circuit 20 and its output becomes "H", reset by the output of the AND circuit 19, and its output becomes "L". Reference numeral 22 denotes a counter for counting the pulses of the clock terminal, 23 denotes a latch for latching and holding the count value of the counter 22, and 24 denotes a CPU for reading the count value held by the latch 23. 25
Is a motor rotation speed detection circuit for detecting the rotation speed of a disk motor which is not shown here, which is an optical disk rotation device, and an optical disk rotation speed detection device for detecting the rotation speed of the optical disk using the motor rotation speed detection circuit. It has become. In this embodiment, six pulses are generated per rotation of the disk.

Although not described in detail, an optical disk device provided with the address information reproducing circuit X described above includes:
In addition to the address information reproducing circuit X, at least an optical disk holding means, a laser light generating means for generating a laser light, a light spot forming means for converging the laser light on the optical disk to form a light spot, and a tracking control amount. It is assumed that the apparatus includes a tracking control amount detecting means to be obtained, a tracking control means for controlling the light spot in the track center direction based on the tracking control amount, and an address detecting means for extracting an address signal.

The operation of the optical disk device according to the present embodiment configured as described above will be briefly described. FIG. 2 shows a waveform when the light spot enters the header area under tracking control of the groove of the DVD-RAM.

First, the tracking error signal in the header area will be described. In the header area, since the address is recorded with a shift of 1/2 track with respect to the tracking direction of the groove (or land), this becomes a disturbance to the tracking control, so that the light spot follows the locus shown in FIG. Does not return to the center of the track immediately after passing through the area.

At this time, when the light spot is located in the first half of the header area, the push-pull tracking error signal indicates that the area c of the four areas of the photodetector 1 is divided.
Since the reflected light detected in the area d and the reflected light detected in the area a are larger than the reflected light detected in the area a and the area b, the output of the differential amplitude device 10 of the address detection circuit X, that is, the push-pull tracking error signal is on the “+” side. Swing. When the light spot is in the latter half of the header area, the reflected light detected in the areas c and d is smaller than the reflected light detected in the areas a and b. , Ie, the push-pull tracking error signal swings to the “−” side. After the light spot has passed through the header area, the push-pull tracking error signal gradually settles to zero as the light spot returns to the center of the track.

On the other hand, the phase difference tracking error signal is
When the light spot is in the first half of the header area, among the four divided areas of the photodetector 1, there is almost no reflected light detected in the area a, so that the reflected lights received in the areas b and d are smaller. , Are larger than the reflected light received in the regions a and c. That is, the phase of the pulse output from the comparator 5 that has binarized the output of the adder 3 is ahead of the phase of the pulse output from the comparator 4 that has binarized the output of the adder 2, that is, The phase comparator 6 determines that the input at the terminal B is ahead of the input at the terminal A, and the output at the terminal C swings to “+”. When the light spot is in the latter half of the header area, the situation is reversed. That is, since there is almost no reflected light detected in the area d, the phase comparator 6 determines that the input at the terminal A is ahead of the input at the terminal B. As a result, the output of the terminal C swings to "-".

The time required for the phase difference tracking error signal until the tracking error signal becomes 0 after passing through the header area is shorter than that of the push-pull tracking error signal, which is defined by (laser wavelength / 6). This is because the depth of the groove of the DVD-RAM is smaller than the phase difference detection which is the groove depth of (laser wavelength / 4), and the detection accuracy is poor.

As described above, in the header area where the address signal is recorded, the tracking error signal becomes a signal as if a disturbance signal was superimposed on the tracking error signal. Therefore, if the tracking error signal is sliced at an appropriate threshold value, for example, Vth, the header area can be detected. The comparator 13 provided in the address detection circuit X is intended to perform this slicing. If the tracking error signal selected by the switch 12 is equal to or higher than Vth, the comparator 13 outputs "H".
Is output, the output of the comparator 13 rises when the light spot enters the header area.

A shift register S composed of flip-flops 14 to 17 and a pulse generation circuit composed of AND circuits 18 to 20 detect a rising edge of the comparator 13 and output a timing signal. After the detection, the latch signal is output from the AND circuit 18 to the AND circuit 19.
, And a start signal is output from the AND circuit 20.

These output signals operate as follows. First, the count value of the counter 22 is latched by a latch signal. Next, the set / reset circuit 21 is reset by the clear signal, the clear terminal of the counter 22 is set to “L”, and the counter 22 is initialized.

When the initialization of the counter 22 is completed, the set / reset circuit 21 is set by the start signal, the clear terminal of the counter 22 is set to "H", and the counting operation of the counter 22 is restarted.

Since a series of these operations is performed every time the light spot enters the header area, the count value latched by the latch signal indicates the time during which the light spot moves between two consecutive header areas, that is, the address period. Means the time interval between signals. That is, this series of operations acts as time interval detecting means for detecting the time interval between the address period signals.

Next, a method of calculating the current position of the light spot using the time interval between the address period signals obtained as described above will be described. Table 1 shows the relationship between the zone number and the sector in the 2.6 Gbyte phase change disk.
According to the RAM standard, the disk is divided from the inner circumference into zone 0, zone 1,..., Zone 23, and has a sector number and a rotation speed specific to each zone.

[0044]

[Table 1]

Each zone has a sector number and a rotation speed unique to each zone, because the DVD-RAM adopts the ZCLV system, and a zone unique to the rotation speed of the m-th zone. When the DVD-RAM is reproduced at the rotation speed of, the address interval signal interval becomes a constant value Tad. Equation (1) shows the relationship between the disk rotation speed N (unit: rpm), the number of sectors, and Tad when the m-th zone is normally reproduced.

[0046]

(Equation 1)

Next, an error occurs for some reason,
If the disk rotation speed in the zone is α times that in the normal case, the address period signal interval is inversely proportional to 1 / α. However, if the condition at the time of this error is inserted into the above equation (1), and the number of sectors in the m-th zone is calculated, an equation similar to the equation (1) is eventually obtained. In other words, it can be seen that the number of sectors in the m-th zone does not change even if an error occurs and the disk rotation speed changes. Equation (2) shows the condition at the time of error inserted into equation (1).

[0048]

(Equation 2)

Therefore, if the current interval (Tad / α) between the address period signals and the current disk rotation speed (α × N) can be detected, the number of sectors where the optical pickup is currently located can be calculated. The interval (Tad / α) between the address period signals is the count value held in the latch 23 provided in the address detection circuit X shown in FIG.

The CPU 24 reads the count value (Tad / α) held by the latch 23 and, at the same time, counts the number of pulses output from the motor rotation speed detection circuit 25 to obtain the disk rotation speed. Is calculated, the optical disk rotating means is controlled to the disk rotational speed of the zone obtained by this calculation, and the number of zones and the initial address are set in the optical disk device, whereby the address can be detected.

Since the present embodiment is as described above, the time interval of the address period signal is detected, the reciprocal of the product of the rotation speed of the optical disk and the time interval of the address period signal is calculated, and the disk at the position of the light spot is calculated. Since the number of address period signals per cycle is calculated, the current zone can be quickly known even if an error occurs.

(Embodiment 2) Next, another example of an optical disk apparatus according to the present invention will be described as a second embodiment with reference to the drawings.

FIG. 3 is a block diagram of the address information reproducing circuit Y in the optical disk device according to the second embodiment. Since the address information reproducing circuit Y has the same configuration as the address information reproducing circuit X described in the first embodiment, the same reference numerals are given to the same members to avoid duplication of description, The description is omitted.

In FIG. 3, reference numerals 18, 26, and 27 denote AND circuits for generating a timing signal using signals of the shift register S composed of flip-flops 14 to 16.

Reference numeral 21 denotes a set / reset circuit, which is set by the output of the AND circuit 18 and the output becomes "H".
The output is reset by the output of the AND circuit 27 and becomes “L”.

Reference numeral 22 denotes a counter for counting the pulses of the clock terminal, 23 denotes a latch for latching and holding the count value of the counter 22, and 24 denotes a CPU for reading the count value held by the latch 23.

Although not described in detail, the optical disk apparatus provided with the address information reproducing circuit Y described above includes, in addition to the address information reproducing circuit Y, at least an optical disk holding means and a laser for generating a laser beam. A light generating means, a light spot forming means for forming a light spot by converging a laser beam on an optical disk, a tracking control amount detecting means for obtaining a tracking control amount, and a light spot in a track center direction based on the tracking control amount. It is assumed that the apparatus includes tracking control means for controlling and address detection means for extracting an address signal.

The operation of the optical disk device according to the present embodiment configured as described above will be briefly described. A shift register S composed of flip-flops 14 to 16 and a pulse generation circuit composed of AND circuits 18 to 20, 26 and 27 detect a rising edge and a falling edge of the comparator 13 and generate a timing signal. After detection, a latch signal is output from the AND circuit 26, a clear signal is output from the AND circuit 27, and a start signal is output from the AND circuit 18.

These output signals operate as shown in FIG. First, when the rising edge of the comparator 13 is detected, the set / reset circuit 21
Is set, the clear terminal of the counter 22 is set to “H”, and the counter operation of the counter 22 is started.

Next, when a falling edge is detected, a latch signal is generated and the count value of the counter 22 is latched. After the latch, the set / reset circuit 21 is reset by a clear signal, the clear terminal of the counter 22 is set to “L”, and the counter 22 is initialized.

At this time, the threshold voltage Vth of the comparator 13
Is set to a positive voltage, the output of the comparator 13 is such that the tracking error signal selected by the switch 12 is + │V
Since “H” is output at the time of th | or more, the counter 22 performs a count operation while the light spot passes through the first half of the header area. If the threshold voltage Vth of the comparator 13 is set to a negative voltage, "H" is output when the tracking error signal is -│Vth│ or less, so that the light spot passes through the latter half of the header area. While the counter 22
Performs a counting operation.

Since this operation is performed every time the light spot passes through the first half or the second half of the header area, the count value latched by the latch signal indicates the time required for the light spot to move half the header area, that is, the address. It means 1/2 of the time of the period signal.

Next, a method of calculating the current position of the light spot by using half the time of the address period signal obtained as described above will be described. Since the header area is at the beginning of each sector and an address signal is recorded here, the address period signal interval Tad described in the first embodiment means the time when the light spot passes through one sector. It is.

In the DVD-RAM standard, since the capacity of the header area and the recording / reproducing area constituting the sector is determined in advance, the time of the address period signal can be expressed using Tad.

Here, assuming that the time of the address period signal is Tcd, this can be expressed as the address period signal interval Tad multiplied by a fixed coefficient β. This is shown in equation (3). Here, β is a known constant.

[0066]

(Equation 3)

The equation (3) is substituted into the equation (1) shown in the first embodiment to obtain an equation (4).

[0068]

(Equation 4)

Next, an error occurs for some reason, and
If the number of disk rotations in the zone is α times as large as when the zone is normal, the address period signal interval is inversely proportional to 1 / α times. However, when the condition at the time of this error is inserted into the above equation (4), and the number of sectors in the m-th zone is calculated, an equation similar to the equation (4) is eventually obtained. In other words, it can be seen that the number of sectors in the m-th zone does not change even if an error occurs and the disk rotation speed changes. Equation (5) shows the condition at the time of error inserted into equation (4).

[0070]

(Equation 5)

Accordingly, if the time (Tcd) of the current address period signal and the current disk rotation speed (α × N) can be detected, the number of sectors where the optical pickup is currently located can be calculated. Then, the time of this address period signal (Tc
d) is nothing but a value obtained by doubling the count value held in the latch 23 provided in the address information reproducing circuit Y shown in FIG.

The CPU 24 reads the count value (Tcd / 2) held by the latch 23 and, at the same time, counts the number of pulses output from the motor speed detection circuit 25 to obtain the disk speed. ) Is calculated, the optical disk rotating means is controlled to the disk rotational speed of the zone obtained by this calculation, and the number of zones and the initial address are set in the optical disk device, whereby the address can be detected.

Since the second embodiment is as described above, the number of address period signals per one round of the optical disk at the position of the optical spot is calculated using the rotation speed of the optical disk and the time width of the address period signal. Therefore, even if an error occurs, the current zone can be quickly known.

[0074]

As described above, according to the optical disk device of the first aspect, the time interval between the address period signals is accurately detected, and the product of the detected time interval between the address period signals and the rotation number of the optical disk. The number of address period signals per optical disc rotation at the current light spot position can be calculated using the reciprocal of the above. Therefore, even if an error occurs during reproduction and the optical pickup flows, By quickly calculating the position of, quick recovery can be realized, which is preferable.

According to the optical disk device of the present invention, the time of the address period signal is accurately detected, and the current light spot is determined by using the relationship between the time interval between the detected address period signals and the rotation speed of the optical disk. It is possible to calculate the number of address period signals per rotation of the optical disk at a position. As a result, even if an error occurs during reproduction and the optical pickup flows, the position where the signal has flowed can be calculated quickly. Thereby, quick recovery can be realized, which is preferable.

[Brief description of the drawings]

FIG. 1 is a block diagram of an address information reproducing circuit according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing an operation of the address information reproducing circuit according to the first embodiment of the present invention.

FIG. 3 is a block diagram of an address information reproducing circuit according to a second embodiment of the present invention.

FIG. 4 is a timing chart showing an operation of an address information reproducing circuit according to a second embodiment of the present invention.

FIG. 5 is a block diagram of a conventional address information reproducing circuit.

FIG. 6 is an enlarged conceptual diagram of a part of a groove and a land of a DVD-RAM.

[Explanation of symbols]

 X Address information reproducing circuit 1 Photodetector 2 Adder 3 Adder 4 Comparator 5 Comparator 6 Phase comparator 7 Low-pass filter 8 Adder 9 Adder 10 Differential amplifier 11 Low-pass filter 12 Switch 13 Comparator 14 Flip-flop 15 Flip-flop Reference Signs List 16 flip-flop 17 flip-flop S shift register 18 logical product circuit 19 logical product circuit 20 logical product circuit 21 set / reset circuit 22 counter 23 latch 24 CPU 25 motor rotation speed detection circuit Y address information reproducing circuit 26 logical product circuit 27 logical product Circuit Z Address information reproducing circuit 101 Comparator 102 Comparator 103 Retriggerable mono-multi 104 OR gate 105 Retriggerable mono-multi 106 Current source 107 Analog switch 108 A Log switch 109 current source 110 analog switch 111 capacitor C charge pump circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D109 KA05 KB05 KB14 KB40 KC03 KC08 KD06 KD11 KD38 KD45 KD46 5D118 AA17 AA24 BA04 BB07 BC12 BC13 BD04 BF02 CA23 CA24 CB03 CB05 CC15 CD03 CD07 CD17 CF05

Claims (2)

[Claims] 1. An optical disk holding means for holding an optical disk having address information intermittently recorded on an information recording surface, an optical disk rotating means for rotating the optical disk, and a laser light generating means for generating a laser beam A light spot forming means for forming a light spot by converging laser light generated by the laser light generating means on an information recording surface of the optical disk; a photodetector for detecting reflected light of the light spot; Phase difference tracking error detection that detects the amount of positional deviation from the center by comparing the addition results of diagonal areas among the areas of the photodetector divided into four by a track direction axis and an axis perpendicular to the axis. Means for determining the amount of displacement between the light spot and the center of the track; A push-pull tracking error detection means for detecting by comparing the addition result of two areas parallel to the track direction among the areas of the photodetector divided into four parts by a direction axis and an axis perpendicular to the axis; Tracking control amount detecting means for obtaining a tracking control amount according to the positional deviation amount; tracking control means for controlling the light spot in the track center direction based on the tracking control amount; and obtaining from the reflected light of the light spot. An address detection unit for extracting an address signal from the reproduced signal, wherein an output from the phase difference tracking error detection unit or the push-pull tracking error detection unit is binarized by a predetermined threshold value. Comparing means for performing the operation, and an output pulse of the binarizing means. Time interval detecting means for measuring a time interval between address period signals by measuring time, optical disc rotation speed detecting means for detecting the rotation speed of the optical disc, and the address per one round of the optical disc at the position of the light spot Calculating means for calculating the number of period signals;
The calculating means calculates a reciprocal of a product of a rotation number of the optical disk detected by the optical disk rotation number detecting means and a time interval between the address period signals detected by the time interval detecting means. An optical disk device, comprising: an optical disk rotation control unit that controls the optical disk rotation unit according to the number of the address period signals calculated by the calculation unit. 2. The optical disk device according to claim 1, wherein the calculating means calculates a rotation speed of the optical disk and a time width of the address period signal calculated based on a time interval between the address period signals. An optical disc device, comprising: calculating a reciprocal of a product by a known fixed coefficient.