JPH11149755A - Disc playback device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a disk reproducing apparatus with further reduced search time. A system control circuit includes a rotation detector.
, The rotation period T ₀ of the disk 1 starting from the start point of the program area during reproduction of the disk 1 and the rotation period of the disk 1 starting from a point different from the start point of the program area during reproduction of the disk 1 Measure T. Then, the system control circuit 10 performs a predetermined calculation using the rotation period T ₀ to obtain the linear velocity V of the disk 1 and the rotation period T ₀ and the rotation period T _0.
The track pitch Tr _P of the disk 1 is obtained by performing a predetermined calculation using Then, the system control circuit 10 generates a track table to be referred at the time of the search based on the obtained linear velocity V and the track pitch Tr _P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk reproducing apparatus for reproducing information from a disk-shaped recording medium having address information and recorded at a constant linear velocity.

[0002]

2. Description of the Related Art As a disc as an information recording medium, C is used.
D, MD, DVD, and the like exist. However, these disk-shaped recording media (hereinafter, referred to as "disks") have a constant linear velocity (position in the radial direction of the disk) because the recording capacity can be maximized. Information is recorded at a constant recording density irrespective of the type of information recorded.

[0003] In addition to information to be recorded, information indicating a position on the disc (hereinafter, referred to as "recording information") is added to the disc.
Address information) is recorded at predetermined intervals, and a disk reproducing apparatus that reproduces information recorded on a disk realizes random access by reading address information.

In a disk reproducing apparatus, when starting reproduction of information recorded on a disk, a pickup as information reading means is moved to a target position on the disk (hereinafter, referred to as a "target address") ( Hereinafter, this is called “search”). In order to perform the search, the current position of the pickup on the disk (hereinafter, referred to as “current address”)
It is necessary to know the number of tracks traversed by the pickup from the device to the target address (hereinafter referred to as "the number of tracks to the target address"), and whether the direction in which the pickup is moved is the inner circumferential direction or the outer circumferential direction. There is.

[0005] Here, in a disk on which information is recorded by the constant linear velocity method, the number of tracks that the pickup traverses from the start point (absolute time address 00: 00: 00: 00) of the program area to the absolute time address A (hereinafter referred to as "the number of tracks"). , "The number of tracks of the absolute time address A") N is given by the following (Equation 1). Here, V is the linear velocity of the disk, Tr _P is the track pitch of the disk, and R _S is the radius of the start point of the program area.

[0006]

[Formula 1]

The number of tracks at the current address and the number of tracks at the target address are obtained by using (Formula 1), whereby the number of tracks up to the target address can be known. Note that the direction in which the pickup is moved can be known from the magnitude relationship between the target address and the current address.

Here, the disc reproducing apparatus has a built-in microcomputer (hereinafter, abbreviated as "microcomputer") for integrally controlling the operation of each component.
It is impossible for this microcomputer to perform the operation on the right side of (Equation 1). For this reason, the right side of (Equation 1) is calculated in advance to determine the number of tracks for each address, which is tabulated (hereinafter, this tabulated table is referred to as a “track table”) and provided to the microcomputer. Keep it. In this way, the current address and the target address are given to the microcomputer, and the number of tracks to the target address is obtained by performing a simple operation using the data obtained by referring to the track table based on the current address and the target address. Can be

Incidentally, the linear velocity V and the track pitch Tr required to perform the operation on the right side of (Equation 1)
_P has various values within a certain range for each disk since some variation is recognized in the specification of the disk. However, information on the linear velocity V and the track pitch Tr _P is not recorded on the disk. That is, the linear velocity V and the track pitch Tr _P
Is not known, and a track table cannot be created as it is. Based on such a situation, the conventional disk reproducing device has taken the following countermeasures.

First, in the disk reproducing apparatus of the first conventional example, the track table is created by fixing the linear velocity to the lower limit of the standard and the track pitch to the upper limit of the standard. According to this, the number of tracks to the target address obtained by referring to the track table does not become larger than the actual value, and the target address can be reached by repeating the search.

Next, in the disk reproducing apparatus of the second conventional example, a track table is created for each of a plurality of linear velocities, and a predetermined search is actually performed based on each of the track tables to obtain a target address. And the arrival address (the address that the pickup reached by performing the search)
Select the track table that minimizes the error.

Next, in the disk reproducing apparatus of the third conventional example, a track table is created by fixing the linear velocity and the track pitch to predetermined values, and a search is performed based on the track table, and the target address and the track address are searched. The data in the track table is corrected according to the error from the actual arrival address.

Next, the disk reproducing apparatus of the fourth conventional example has a means for moving the pickup with high accuracy, so that the pickup can accurately cross the predetermined number of tracks, and before and after the movement. Address, and
The linear velocity is calculated from the number of tracks that have crossed the pickup.

Finally, the fifth prior art disk reproducing apparatus has means for detecting the physical movement amount of the pickup, so that the target address and the actual arrival address at the time of performing a predetermined search are determined. The linear velocity is obtained from the relationship between the error and the amount of movement of the pickup.

[0015]

However, the above-mentioned conventional disk reproducing apparatus has the following problems. First, in the disk reproducing apparatus of the first conventional example, only one track table is required. However, for most disks, a search operation is performed a plurality of times before the pickup reaches the target address. Speed is slow.

Further, the disk reproducing device of the second conventional example has a limit in the number of track tables, and cannot cope with disks with so many kinds of linear velocities. Even if we could have a track table for each type of linear velocity,
There are the following problems. This problem is related to the third conventional disk reproducing apparatus.

Here, the disc reproducing apparatus counts the number of tracks crossed by the pickup based on a track cross signal obtained while the pickup is moving,
When the target count value is reached, the movement of the pickup ends.However, the track cross signal is missing due to dirt or scratches on the disc, the disc is eccentric, the quality of the track cross signal at the start or end of the movement of the pickup, etc. As a result, the number of tracks crossed by the pickup cannot be accurately counted, and therefore, the movement of the pickup itself includes an error.

Therefore, even if the pickup is moved under the same condition, the actual arrival address varies, and the track table to be selected does not converge in the disk reproducing device of the second conventional example, and the track is selected in the disk reproducing device of the third conventional example. The data in the table does not converge. As a result, the number of tracks up to the target address cannot be obtained accurately, and a high-speed search has not been realized.

Further, in the fourth and fifth conventional disk reproducing apparatuses, only the linear velocity is obtained despite two uncertainties of the linear velocity and the track pitch. This is because the track pitch generally has a smaller effect on the calculation result on the right side of (Equation 1) than the linear velocity.
After the track pitch is fixed, the linear velocity is obtained by the above-described methods. As described above, as long as the track pitch is fixed, the number of tracks up to the target address cannot be accurately obtained for a disk having a track pitch different from the fixed value, and the search cannot be sped up. .

Accordingly, it is an object of the present invention to provide a disk reproducing apparatus in which the search time is further reduced.

[0021]

According to the present invention, there is provided a disk reproducing apparatus for reproducing information from a disk recorded with a constant linear velocity method. The linear velocity of the disk is calculated based on the time required for the disk to make one revolution after recognizing the start point of the program area during the reproduction of.

The track pitch of the disk is determined by performing a predetermined calculation using the time required from the recognition of the start point of the program area during the reproduction of the information recorded on the disk to one rotation of the disk. Even if not, the linear velocity of the disk can be calculated. Therefore, the linear velocity of the disk calculated by the above configuration is accurate.

When the start point of the program area is recognized during the reproduction of the information recorded on the disc,
The track pitch of the disk is determined based on the time required for rotation and the time required for the disk to make one rotation after recognizing a point different from the start point of the program area during reproduction of information recorded on the disk. calculate.

The time required from the recognition of the start point of the program area during the reproduction of the information recorded on the disk to the rotation of the disk once, and the start point of the program area during the reproduction of the information recorded on the disk By performing a predetermined calculation using the time required for the disk to make one revolution after recognizing a point different from the above, it is possible to calculate the track pitch of the disk even if the linear velocity of the disk is not determined. it can. Therefore, the track pitch of the disk calculated by the above configuration is accurate.

The number of tracks from the start point of the program area to each address is calculated based on the calculated linear velocity and track pitch of the disk.

The number of tracks from the start point of the program area to each address calculated by the above configuration is very accurate.

Also, a rotation detector for performing a predetermined detection output at least once during one rotation of the disk is provided, and the reproduction state is set immediately before the start point of the program area, and immediately after the start point of the program area is recognized. The time from when the detection output of the rotation detector is generated for the first time to when there is a detection output of the rotation detector corresponding to one rotation of the disk is measured, and the measured time is used as the information of the information recorded on the disk. This is the time required from the recognition of the start point of the program area during the reproduction to the rotation of the disc by one revolution.

The time measured by the above configuration means that the time required from the reproduction of the position advanced by one track at a maximum from the start point of the program area to the rotation of the disk once is measured. Here, the time required from the reproduction of the track including the start point of the program area to the rotation of the disk by one revolution and the position advanced by one track around the track from the start point of the program area are reproduced, and then the disc is rotated by one rotation. As a result of theoretically calculating and comparing the time required to perform the operation, the state is almost equal to the difference. Therefore, the time required from the recognition of the start point of the program area during the reproduction of the information recorded on the disk obtained by the above configuration to one rotation of the disk is accurate. It should be noted that the rotation detector can be configured to perform the detection output in a cycle shorter than the update cycle of the address information recorded on the disk, so that the rotation detector can be more accurate.

Also, the time from when the start point of the program area is recognized until the rotation detector generates the detection output for the first time is measured, and the measured time and the separately measured start point of the program area are measured. During the reproduction of the information recorded on the disc, based on the time from when the detection output of the rotation detector is generated immediately after the recognition of the disc to when there is the detection output of the rotation detector corresponding to one revolution of the disc. The time required from the recognition of the start point of the program area to one revolution of the disk is calculated.

With the above configuration, it takes a time from the recognition of the start point of the calculated program area to the rotation of the disk by one rotation regardless of the rotation detector (regardless of the period at which the rotation detector performs detection output). Time will be accurate.

Further, a memory as storage means is provided, and when the specific information which is the information recorded in a predetermined area of the disk is read, the same information as the read specific information is not stored in the memory. In this case, the read specific information is stored in the memory, and the linear velocity of the disk, or the linear velocity and the track pitch are calculated and stored in the memory in association with the read specific information. If the same information as the read specific information is stored in the memory, the read specific information is not stored in the memory, and the linear velocity of the disk,
Alternatively, without calculating the linear velocity and the track pitch, the data stored in the memory in association with the read specific information is set as the linear velocity of the disk or the linear velocity and the track pitch.

With the above structure, once the linear velocity of the disk, or the disk for which the linear velocity and the track pitch have been calculated, the linear velocity of the disk, or
There is no need to calculate the linear velocity and the track pitch.

Since the storage capacity of the memory is limited, when the memory is used as described above, when various kinds of discs are reproduced, the memory has no free space. Therefore, a configuration as described below may be adopted in preparation for when the free space of the memory is exhausted.

For example, when the same information as the specific information read from the disk is not stored in the memory,
If there is no free space in the memory, a free space is secured in the memory by erasing information stored in the memory from the oldest, and the read specific information;
Further, the calculated linear velocity of the disk, or the linear velocity and the track pitch are stored in the memory.

Alternatively, when the same information as the specific information read from the disk is stored in the memory, the frequency counter corresponding to the area where the information is recorded is counted up, and the specific information read from the disk is counted. If the same information as the information is not stored in the memory, and there is no free space in the memory, the information stored in the area where the count value of the corresponding frequency counter is the smallest is erased to clear the free space in the memory. Reserve space,
The read specific information and the calculated linear velocity of the disk, or the linear velocity and the track pitch are stored in the memory.

Also, information specific to each disk read from the disk during the initial operation is associated with specific information read from the disk in the same manner as the calculated linear velocity of the disk or the linear velocity and the track pitch. When the specific information is read from the disk, and the read specific information is stored in the memory, the data stored in the memory is recorded on the disk in association with the read specific information. If the information is unique to each disc that has been read, once the information unique to each disc is read out,
There is no need to read out the specific information again.

In addition, by activating the focus servo after the number of rotations of the disk reaches the specified value, the focus-in process is stabilized.

When stopping the rotation of the disk,
By determining whether or not the disk has stopped based on the rotational speed of the disk, the spindle motor is braked stably.

[0039]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a disk reproducing apparatus 100 according to an embodiment of the present invention. In the figure, 1 is a disk, 2 is a spindle motor, 3 is a rotation detector, 4 is a pickup, 5 is a slide motor, 6 is an RF amplifier, 7 is a motor driver,
8 is a servo signal processing circuit, 9 is a CD-ROM decoder,
Reference numeral 10 denotes a system control circuit, 11 denotes a RAM, and 12 denotes a nonvolatile memory.

The operation of each section will be described below. The spindle motor 2 rotates the disk 1 as an information recording medium. The rotation detector 3 performs a detection output (for example, one pulse) at least once during one rotation of the disk 1, and based on the detection output of the rotation detector 3, the system control circuit 10 determines a rotation cycle of the disk 1. And rotation speed. The pickup 4 is a head that irradiates the disk 1 with light and takes in reflected light from the disk 1 and reads out an RF signal (modulated data) recorded on the disk 1. The slide motor 5 moves the optical pickup 4 in the radial direction of the disk 1.

The RF amplifier 6 amplifies the RF signal read by the pickup 2. The motor driver 7 is involved in irradiating light to the spindle motor 2, the slide motor 4, and the disk 1 and injecting reflected light from the disk 1.
The respective driver circuits for driving actuators (not shown) for moving an objective lens (not shown) in the pickup 3 are combined into one.

Under the control of the system control circuit 10, the servo signal processing circuit 8 performs predetermined processing on the RF signal amplified by the RF amplifier 6, outputs the processed signal to the CD-ROM decoder 12, and outputs the signal from the pickup 4. The above-mentioned motors and actuators driven by the motor driver 7 are feedback-controlled so that the operation such as following the track on the disk 1 is performed accurately. The control of the spindle motor 2 is appropriately performed by the system control circuit 10 based on the detection output of the rotation detector 3 as described later.

The CD-ROM decoder 9 is connected to a host device 200 which is an external device.
The command input from 0 is given to the system control circuit 10, and the data read from the disk 1 (the signal from the servo signal processing circuit 8) is demodulated.
The operation of transferring the data to the host device 200 is performed under the control of the system control circuit 10.

The system control circuit 10 controls the servo signal processing circuit 8 and the CD-ROM decoder 9 as described above, receives a command from the host device 200 input to the CD-ROM decoder 9, and An instruction is sent to the servo signal processing circuit 8 so that data to be transferred to the servo signal processing circuit 8 is read.

The RAM 11 is provided for operations such as the system control circuit 10 performing calculations. The non-volatile memory 12 is for storing data read from the disk 1, results of calculations performed by the system control circuit 10, and the like.

In the following, the disc 1 is set with the power to the disc reproducing apparatus turned on, or
The process performed by the system control circuit 10 in the initial operation performed when the device is replaced or when the apparatus is powered on with the disk 1 set is described with reference to the flowchart shown in FIG.

First, the servo signal processing circuit 8 is instructed to move the pickup 4 to the vicinity of the innermost circumference of the disk 1 in which the TOC information is stored (hereinafter referred to as "TOC area") (# 201). Accordingly, the servo signal processing circuit 8 drives the slide motor 5 via the motor driver 7.

When the movement of the pickup 4 to the TOC area is completed, the servo signal processing circuit 8 is instructed to start the spindle motor 2 and the detection output of the rotation detector 3 is monitored. When the number of rotations is reached, the spindle motor 2 is controlled via the servo signal processing circuit 8 and the motor driver 7 so that the number of rotations is maintained (# 202).

Then, the servo signal processing circuit 8 is instructed to start the focus servo, then, the tracking servo is started, and then the control of the spindle motor 2 is transferred to the servo signal processing circuit 8. Command to start the spindle servo (# 2)
03). When these servos are locked, the pickup 4 enters a reproduction state in which information recorded on the disk 1 is read.

As described above, in the disk reproducing apparatus of the present embodiment, the focus servo is started after the system control circuit 10 confirms that the disk 1 has reached the specified number of revolutions based on the detection output of the rotation detector 3. Focus-in processing is stabilized.

By the way, during the initial operation or during the reproducing state, the disc 1 becomes dirty or scratched,
Servo errors may occur due to impact on the device. In such a case, the recovery process is performed. In some cases, however, the spindle servo runs out of control, causing the disk 1 to rotate at an abnormally high speed, which causes a problem that a signal cannot be read.

When the rotation of the disk 1 is stopped, the spindle motor 2 is reversely braked. However, it is determined whether or not the disk 1 has stopped based on a reproduction signal in a state where the focus servo is locked. In such a case, the focus servo may be displaced due to some disturbance, and the spindle motor 2 may fall into a high-speed reverse rotation state.

Therefore, in the disk reproducing apparatus of the present embodiment, while the disk 1 is rotating, the system control circuit 10 constantly monitors the detection output of the rotation detector 3, and when the system goes out of control, the detection of the rotation detector 3 is performed. The system control circuit 10 controls the spindle motor 2 via the servo signal processing circuit 8 based on the output. When stopping the rotation of the disk 1, the system control circuit 10 determines whether or not the rotation of the disk 1 has stopped based on the detection output of the rotation detector 3, and stably brakes the spindle motor 2. Multiply.

As described above, in the disc reproducing apparatus according to the present embodiment, the disc 1 can be stopped even when the focus servo is deviated by effectively utilizing the detection output of the rotation detector 3. I have.

Incidentally, in a recent disk reproducing apparatus,
In most cases, a brushless motor that generates a large torque is used as the spindle motor 2 for the purpose of improving reliability and supporting a plurality of double speeds. In response to this, the rotation detector 3 is originally built in. I have. That is, the rotation detector 3 is not newly provided in the disk reproducing apparatus of the present embodiment, and does not lead to an increase in cost.

When the reproduction state is set, the system control circuit 10 acquires subcode information from the read data (# 204). Based on this information, it is determined whether the pickup 4 is located in the TOC area (# 20).
5) If not located in the TOC area (N of # 205), the servo signal processing circuit 8 is instructed to perform a track kick (moving the pickup 4 by a relatively small number of tracks) (# 206). Pickup 4 is T
This operation is repeated until the OC area is reached.

In the TOC area, information such as the total reproduction time, the total number of music pieces, the start time of each music piece, the data type of each music piece (hereinafter referred to as “TOC information”) is recorded in the form of subcode information. As soon as the TOC information is obtained, it is stored in the nonvolatile memory 12 (# 207). Next, disk 1
The process proceeds to the process of calculating the linear velocity V (# 208). After the calculation of the linear velocity V of the disk 1, the process proceeds to a process of calculating the track pitch Tr _P of the disk 1 (# 209).

Processing for calculating the linear velocity V of the disk 1 (#
208) will be described. Immediately after acquiring the TOC information, the pickup 4 is located in the TOC area,
First, the pickup 4 is moved to the program area by performing a predetermined number of track kicks in the outer circumferential direction. Then, the current position (absolute time address) of the pickup 4 is recognized by reading the subcode information in the reproduction state as it is.

Next, the absolute time address 00:01:00
Search nearby. This search is performed using a default track table. When the search is completed and the pickup 4 reaches the position of the absolute time address 00:01:00, a predetermined number of track kicks are performed in the inner circumferential direction. Thus, if the predetermined number of tracks to be kicked is set appropriately, the pickup 4 reaches a position near the boundary between the TOC area and the program area and immediately before the start point of the program area. Then, the playback state is left as it is, the subcode information is monitored, and the pickup 4 reaches the start point of the program area (the absolute time address 00:
00:00 is obtained).

When the pickup 4 reaches the program area, the rotation period of the disk 1 starting from the start point of the program area (the time required for the disk 1 to make one rotation after recognizing the start point of the program area during information reproduction) ). This is performed as follows.

First, when the rotation detector 3 performs detection output in a cycle shorter than the address information update cycle (normally 13.3 ms at 1 × speed), when the start point of the program area is recognized, the rotation detector 3 is generated immediately after that. The timer is started with the detection output of the rotation detector 3 and the timer is stopped with the detection output of the rotation detector 3 corresponding to just one rotation of the disk 1. As a result, the rotation period of the disk 1 starting from a position that is shorter than the address update period from the start point of the program area by the disk 1 is measured, and this measurement result is used as the rotation period of the disk 1 starting from the start point of the program area. And

On the other hand, when the rotation detector 3 does not perform detection output in a cycle shorter than the update cycle of the address information, it is the same as when the rotation detector 3 performs detection output in a cycle shorter than the update cycle of the address information. By simply doing so, the rotation period t ₁ of the disk 1 starting from a position at most one track round from the start point of the program area is measured. When another detection output of the rotation detector 3 is generated for the first time immediately after the start point of the program area is recognized immediately after the start point of the program area is recognized, the timer is stopped, so that the start point of the program area is recognized and immediately thereafter. detection outputs of the rotation detector 3 previously measures the time t ₂ until the first time occurs, or rotation detector immediately after recognizing the start point of the program area The address information A when the detection output of No. 3 is generated for the first time is stored.

Then, a result obtained by performing a predetermined correction based on the measured rotation period t ₁ or the rotation period t ₂ or the address information A is set as a rotation period of the disk 1 starting from the start point of the program area. Note that the result obtained by the above correction is substantially equal to the rotation period of the disk 1 starting from the theoretically calculated start point of the program area. As described above, even when the rotation detector 3 does not perform the detection output in a cycle shorter than the update cycle of the address information, the rotation cycle of the disk 1 starting from the start point of the program area can be obtained.

It should be noted that the rotation period t ₁ of the disk 1 may be adopted as it is as the rotation period of the disk 1 starting from the start point of the program area. This is because there is almost no difference between the rotation period of the disk 1 starting from the start point of the program area and the rotation period of the disk 1 starting from the point included on the next track. However, it goes without saying that the correction is more accurate as described above.

Also, when the rotation detector 3 performs detection output in a cycle shorter than the address information update cycle, there are cases where the rotation detector 3 does not perform detection output in a cycle shorter than the address information update cycle. The correction may be performed after the same measurement is performed. In this case, the rotation cycle of the disk 1 starting from the start point of the program area can be obtained more accurately.

The process of calculating the rotation cycle of the disk 1 starting from the start point of the program area is performed a plurality of times.
The average value of a plurality of obtained results may be adopted as the rotation cycle of the disk 1 starting from the start point of the program area. By doing so, the rotation cycle of the disk 1 starting from the start point of the program area can be obtained more accurately.

Here, the rotation period of the disk 1 starting from the absolute time address A is T _A , the linear velocity of the disk 1 is V,
Assuming that the track pitch of the disk 1 is Tr _P and the radius of the start point of the program area is R _S ,
Holds.

[0068]

[Formula 2]

Since the absolute time address of the start point of the program area is 0, assuming that the rotation cycle of the disk 1 starting from the start point of the program area is T ₀ , the above equation (2)
Thus, the following (Equation 3) is obtained.

[0070]

[Equation 3]

The above (Equation 3) does not include the track pitch Tr _P of the disk 1 as an element. That is,
Even if the track pitch Tr _P of the disk 1 is not determined, the linear velocity V of the disk 1 can be obtained by using the rotation period T ₀ of the disk 1 starting from the start point of the program area.

Now, in the disc reproducing apparatus of the present embodiment, the rotation period T ₀ of the disc 1 starting from the start point of the program area is obtained as described above.
By calculating the right side of (Equation 3), the linear velocity V of the disk 1 is calculated. As described above, in the disk reproducing apparatus of the present embodiment, the rotation period T ₀ of the disk 1 starting from the start point of the program area is obtained, and the linear velocity V of the disk 1 is calculated based on the obtained result.

Next, in the disk reproducing apparatus of the present embodiment, as shown in FIG. 3, the linear velocity V and the track pitch T of the disk 1 are used as a default track table.
Table 1 where r _P is V = 1.2 m / s and Tr _P = 1.5 μm, respectively, V = 1.4 m / s, Tr _P = 1.5 μ
m, Table V, V = 1.2 m / s, Tr _P = 1.
Table 3, 6 μm, V = 1.4 m / s, Tr _P =
Four types of track tables of Table 4 having a size of 1.6 μm are prepared. The figure shows the number of tracks for each absolute time address. Note that the absolute address is from 0 minutes to 8
Although the number of tracks is shown in increments of 10 minutes up to 0 minutes, the number of tracks is actually shown in smaller increments.

Then, by interpolating the number of tracks N ₀ of the tables 1 and 2 based on the calculated linear velocity V of the disk 1, the track pitch Tr _P =
By calculating the number of tracks at each absolute time address in a 1.5 μm disk, and by interpolating the number of tracks N ₀ of the track table 3 and the track table 4 based on the calculated linear velocity V of the disk 1, , The number of tracks at each absolute time address on a disk having a track pitch Tr _P = 1.6 μm is calculated. That is,
The track number N ₁ of the absolute time address A is given by (Equation 4) shown below.

[0075]

(Equation 4)

A specific example will be described. Assuming that the calculated linear velocity V is 1.25 m / s, the number of tracks calculated for each absolute time address is represented by a linear velocity V of 1.25 m / s.
FIG. 4 shows Tables 5 and 6 in which theoretical values when the track pitch is set to 1.5 μm and 1.6 μm, respectively, and errors with respect to the theoretical values. As can be seen from the figure, the error is kept small relative to the actual number of tracks at each absolute time address. The error can be further reduced by performing the correction.

For example, FIG. 5 shows a table 5 'and a table 6' in which results obtained by adding a correction value N ₁ 'obtained by the following (Equation 5) to the number of tracks N ₁ are summarized. From the figure, it can be seen that a very accurate number of tracks within three errors from the theoretical value is obtained.

[0078]

(Equation 5)

The process of obtaining the number of tracks as described above may be performed at a time when the linear velocity V is calculated, or may be performed during a drive idle time. Alternatively, only the number of tracks necessary for the search may be performed at the time of the search.

Next, the track pitch Tr _{P of the} disk 1
The process (# 209) of calculating (# 209) will be described. First,
Predetermined absolute time address, for example, searches the 01:00:00, disk 1 starts the rotation cycle T ₆₀ of the disc 1 starting from this address, from the start of the program area
Is measured in the same manner as when measuring the rotation cycle.

Here, the track pitch Tr _P is obtained by the following (Equation 6). Here, T ₀ is the rotation cycle of the disk 1 starting from the start point of the program area,
_A is the rotation cycle of the disk 1 starting from the absolute time address A, and R _S is the radius of the start point of the program area.

[0082]

(Equation 6)

In the disc reproducing apparatus of this embodiment, the rotation period T _{0 of} the disc 1 starting from the start point of the program area and the absolute time address 01: 00: ₀
Since the rotation period T ₆₀ of the disk 1 starting from the above is obtained as described above, T _A is defined as T ₆₀ (Equation 3).
, The track pitch Tr _P of the disk 1 is calculated. As described above, in the disk reproducing apparatus of the present embodiment, the rotation period T _{0 of} the disk 1 starting from the start point of the program area and the point different from the start point of the program area (in the present embodiment, the absolute time address 0)
1:00:00), the rotation period of the disk 1 is obtained, and the track pitch Tr _P of the disk 1 is calculated based on the obtained result.

Next, at the stage when the linear velocity V of the disk 1 has been calculated, the data of the default track table are interpolated in proportion and further corrected, and the tables 5 'and 6' shown in FIG. The number of tracks N ₁ + N ₁ ′ is proportionally interpolated based on the calculated track pitch Tr _P of the disk 1 to obtain the number of tracks for each absolute address time. That is, the track number N of the absolute time address A
₂ is given by (Equation 7) shown below. The track number N ₂ thus obtained is based on the linear velocity V of the disk 1 and the track pitch Tr _P , and an accurate track table can be obtained.

[0085]

[Formula 7]

A specific example will be described. Assuming that the calculated linear velocity V is 1.57 μm, the number of tracks calculated for each absolute time address is the theoretical value when the linear velocity V is 1.25 m / s and the track pitch is 1.57 μm. FIG. 6 shows a table 7 summarizing the errors together with the errors. As can be seen from the figure, the error is kept very small with respect to the actual number of tracks at each address. The error can be further reduced by performing the correction.

For example, FIG. 7 shows a table 7 'in which the results obtained by adding the correction value N "obtained by the following (Equation 8) to the number of tracks N are shown in FIG. It can be seen that a very accurate number of tracks within the number of tracks is obtained.

[0088]

(Equation 8)

When comparing Table 7 with Table 7 ', Table 7 has a smaller error with respect to the theoretical value than Table 7'. ', table 6' be for the canceled accidentally at the stage of calculating the number of tracks N ₂ by an error contained in the (formula 7), in general,
The error becomes smaller when the correction is performed by adding the correction value N ₂ ′ obtained by (Equation 8) to the track number N ₂ obtained by (Equation 7).

The process of obtaining the number of tracks as described above may be performed at a time when the track pitch Tr _P is calculated, or may be performed during the idle time of the drive. Alternatively, only the number of tracks necessary for the search may be performed at the time of the search.

The table 7 ′ finally obtained as shown in FIG. 7 is stored in the RAM 11 and is referred to when performing a search. That is, since the number of tracks to the target address = (the number of tracks of the target address)-(the number of tracks of the current address), the number of tracks of the current address and the number of tracks of the target address are obtained by referring to the track table. By performing the above calculation based on the number of tracks, the number of tracks to the target is obtained, and if the value is positive, the track is picked up in the outer circumferential direction, and if the value is negative, the track is picked up in the inner circumferential direction. 4 would be moved.

A table 7 'shown in FIG. 7 is stored in the RAM 11. For example, when the current address is 10 minutes and the target address is 40 minutes, a search is performed.
By referring to the track table stored in the RAM 11, the number of tracks at address 10 and the number of tracks at address 40 are 4216 and 13431, respectively.
Since the number of tracks is found to be the number of tracks, the number of tracks up to the target address is obtained as a positive number of 13431-4216 = 9215, and the processing shifts to processing for moving the pickup 4 by 9215 tracks in the outer circumferential direction.

In the disc reproducing apparatus of this embodiment, the calculated linear velocity V or the calculated linear velocity V and the track pitch Tr _P are recorded in a predetermined area of the disk 1. The information is read out and stored in the nonvolatile memory 12 in association with the specific information stored in the nonvolatile memory 12. Further, information unique to each disk and required to be acquired at the time of the initial operation (for example, disk size, result of servo automatic adjustment, etc.) is also associated with the above-mentioned specific information in the nonvolatile memory 1.
2 may be stored.

When the specific information is read out, the specific information is searched for in the nonvolatile memory 12. If the read specific information is stored in the nonvolatile memory 12, the specific information is stored in the nonvolatile memory 12. In addition, the calculation of the linear velocity V of the disk and the calculation of the track pitch Tr _P of the disk are not performed, and the data stored in the nonvolatile memory 12 in association with the specific information is not stored in the disk. Used as the speed V and the track pitch Tr _P.

If information that is unique to each disk and needs to be acquired at the time of the initial operation is also stored in the nonvolatile memory 12 in association with the specific information, the read specific information Is stored in the non-volatile memory 12 so that the specific information is not obtained at the time of the initial operation, and the data stored in the non-volatile memory 12 in association with the specific information is stored in the non-volatile memory 12. Use as information.

As described above, for a disk for which the linear velocity V and the track pitch Tr _P of the disk have been calculated once, and for a disk for which information specific to each disk has been once read, the linear velocity V and the disk velocity of the disk have been obtained, respectively. Since the calculation of the track pitch Tr _P and the reading of information unique to each disk need not be performed, the time required for the initial operation can be reduced. The specific information may be, for example, TOC information read at the time of the initial operation.

Since the storage capacity of the non-volatile memory 12 is limited, if the non-volatile memory 12 is used as described above, if various types of discs are reproduced, the non-volatile memory 12 Is gone.

Therefore, when the same information as the specific information read from the disk 1 is not stored in the nonvolatile memory 12 and there is no free space in the nonvolatile memory 12, the read specific information and the calculated information are calculated. The linear velocity V of the disk 1, or the linear velocity V and the track pitch Tr
_P is erased from the oldest stored information and stored in the nonvolatile memory 12.

Alternatively, when the same information as the specific information read from the disk 1 is stored in the nonvolatile memory 12, the frequency counter corresponding to the area where the information is recorded is counted up, and When the same information as the read specific information is not stored in the nonvolatile memory 12 and there is no free space in the nonvolatile memory 12, the read specific information and the calculated linear velocity V of the disk 1 or , The linear velocity V and the track pitch Tr _P in the non-volatile memory 1 by erasing the information stored in the area where the count value of the frequency counter is the smallest.
Stored in 2. When the information is deleted, the count value of the frequency counter corresponding to the area where the information is stored is reset to 0.

In the manner described above, it is possible to cope with a case in which the non-volatile memory 12 runs out of free space. In the former case, a recently reproduced disk is used. In the latter case, a frequently reproduced disk is used. Can reduce the time required for the initial operation.

[0101]

As described above, according to the disk reproducing apparatus of the first aspect, it is possible to accurately calculate the linear velocity of the disk even if the track pitch of the disk is not determined.

Further, according to the disk reproducing apparatus of the second aspect, the track pitch of the disk can be accurately calculated even if the linear velocity of the disk is not determined.

According to the third aspect of the present invention, the number of tracks from the start point of the program area to each address can be accurately calculated, and the track table storing the calculated number of tracks can be used. By performing the search, the search time can be reduced.

Further, according to the disk reproducing apparatus of the fourth aspect, the rotation period of the disk starting from the start point of the program area can be accurately obtained.

Further, according to the disk reproducing apparatus of the present invention, the rotation period of the disk starting from the start point of the program area can be accurately obtained without using the rotation detector.

According to the disk reproducing apparatus of the sixth aspect, the rotation period of the disk starting from the start point of the program area can be obtained more accurately.

According to the disk reproducing apparatus of the present invention, once the linear velocity of the disk, or the linear velocity and the track pitch of the disk have been calculated, the linear velocity of the disk or the linear velocity and the track Since there is no need to calculate the pitch, the time required for the initial operation can be reduced.

Further, according to the disk reproducing apparatus of the eighth aspect, it is possible to cope with the case where the memory has run out of free space so that the time required for the initial operation of the recently reproduced disk can be shortened.

Further, according to the disk reproducing apparatus of the ninth aspect, it is possible to cope with a case where there is no free space in the memory so as to shorten the time required for the initial operation for a disk reproduced at a high frequency. it can.

According to the disk reproducing apparatus of the tenth aspect, it is not necessary to read the information peculiar to the disc once the information peculiar to the disk is read out, so that the time required for the initial operation is reduced. Can be further reduced.

According to the disk reproducing apparatus of the eleventh aspect, the focus-in processing can be stabilized.

According to the disk reproducing apparatus of the twelfth aspect, the disk can be stopped even when the focus servo is off.

[Brief description of the drawings]

FIG. 1 is a block diagram of a disk reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a process performed by a system control circuit in an initial operation.

FIG. 3 is a diagram showing four types of default track tables.

FIG. 4 is a diagram showing a track table obtained based on a calculated linear velocity.

FIG. 5 is a diagram showing a track table obtained by performing correction on the track table of FIG. 4;

FIG. 6 is a diagram showing a track table obtained based on a calculated track pitch.

FIG. 7 is a diagram showing a track table obtained by performing correction on the track table of FIG. 6;

[Explanation of symbols]

 Reference Signs List 1 disc 2 spindle motor 3 rotation detector 4 pickup 5 slide motor 6 RF amplifier 7 motor driver 8 servo signal processing circuit 9 CD-ROM decoder 10 system control circuit 11 RAM 12 nonvolatile memory

Claims (12)

[Claims] 1. A disk reproducing apparatus for reproducing information from a disk-shaped recording medium recorded with a constant linear velocity method, after recognizing a start point of a program area during reproduction of information recorded on the disk-shaped recording medium. A disc reproducing apparatus for calculating a linear velocity of a disc-shaped recording medium based on a time required for the disc-shaped recording medium to make one revolution. 2. The time required from the recognition of the start point of the program area during the reproduction of the information recorded on the disk-shaped recording medium until the disk-shaped recording medium makes one revolution, and the time recorded on the disk-shaped recording medium. A step of recognizing a point different from the start point of the program area during reproduction of the information, and calculating a track pitch of the disk-shaped recording medium based on a time required until the disk-shaped recording medium makes one rotation. The disk playback device according to claim 1. 3. The disk reproduction according to claim 2, wherein the number of tracks from the start point of the program area to each address is calculated based on the calculated linear velocity and track pitch of the disk-shaped recording medium. apparatus. 4. A rotation detector for performing a predetermined detection output at least once during one rotation of the disk-shaped recording medium, and makes a reproduction state immediately before a start point of a program area,
Immediately after the start point of the program area is recognized, the time from when the detection output of the rotation detector is generated for the first time to when there is the detection output of the rotation detector corresponding to one rotation of the disk-shaped recording medium is measured. The measured time is defined as the time required from the recognition of the start point of the program area during the reproduction of the information recorded on the disk-shaped recording medium until the disk-shaped recording medium makes one revolution. 1
4. The disk reproducing device according to any one of items 1 to 3. 5. A time period from when the start point of the program area is recognized until when the rotation detector generates a detection output for the first time is measured, and the measured time and the start point of the measured program area are measured. Is recorded on the disk-shaped recording medium on the basis of the time from when the detection output of the rotation detector is generated immediately after recognizing the rotation to the detection output of the rotation detector corresponding to one rotation of the disk-shaped recording medium. 5. The disk reproducing apparatus according to claim 4, wherein a time required from the recognition of the start point of the program area during the reproduction of the information to the rotation of the disk-shaped recording medium by one revolution is calculated. 6. The disk reproducing apparatus according to claim 4, wherein the rotation detector performs detection output at a cycle shorter than a cycle of updating address information recorded on the disk-shaped recording medium. 7. When a specific information which is information recorded in a predetermined area of a disk-shaped recording medium is read out, the same information as the read specific information is stored in the memory. If it is not stored, the read specific information is stored in the memory, and the linear velocity of the disk-shaped recording medium, or the linear velocity and the track pitch are calculated, and the linear velocity is associated with the read specific information. When the same information as the read specific information is stored in the memory, the read specific information is not stored in the memory, and the linear velocity of the disk-shaped recording medium, or , Without calculating the linear velocity and the track pitch, the data stored in the memory in association with the read specific information is stored in the disk-shaped recording medium. 7. The disc reproducing apparatus according to claim 1, wherein the disc reproducing apparatus has a speed, a linear speed, and a track pitch. 8. If the same information as the specific information read from the disk-shaped recording medium is not stored in the memory, and if there is no free space in the memory, the information stored in the memory from the oldest is read. An empty area is secured in the memory by erasing, and the read specific information and the linear velocity or the linear velocity and the track pitch of the disk-shaped recording medium to be calculated are stored in the memory. Item 8. A disk reproducing apparatus according to Item 7. 9. When the same information as the specific information read from the disk-shaped recording medium is stored in the memory, a frequency counter corresponding to the area where the information is recorded is counted up, When the same information as the specific information read from the recording medium is not stored in the memory, if there is no free area in the memory, the information stored in the area where the corresponding frequency counter has the smallest count value is deleted. 8. The apparatus according to claim 7, wherein a free area is secured in the memory, and the read specific information and the linear velocity or the linear velocity and the track pitch of the disk-shaped recording medium to be calculated are stored in the memory. A disk playback device according to claim 1. 10. When reading specific information which is information recorded in a predetermined area of a disk-shaped recording medium, if the same information as the read specific information is not stored in the memory, a disc-shaped information is read. Read information unique to each disc-shaped recording medium recorded on the recording medium,
When the same information as the read specific information is stored in the memory, the information is stored in the memory in association with the read specific information. 10. The disk reproducing apparatus according to claim 7, wherein the data stored in the disk-shaped recording medium is information unique to each disk-shaped recording medium. 11. The disk reproducing apparatus according to claim 1, wherein the focus servo is started after the number of rotations of the disk-shaped recording medium reaches a specified value. 12. The method according to claim 1, wherein when stopping the rotation of the disk-shaped recording medium, it is determined whether or not the disk-shaped recording medium has been stopped based on the number of rotations of the disk-shaped recording medium. A disk playback device according to claim 1.