JP3124220B2 - Optical disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus of a constant linear velocity system.

[0002]

2. Description of the Related Art FIG. 4 shows a block diagram of a CD reproducing apparatus which is one of the optical disk reproducing apparatuses. In the figure, 1 is an optical pickup, 1a is an objective lens, 2 is an RF amplifier,
3 is a decoder / signal processing circuit, 4 is a memory controller, 5 is a memory, 6 is a D / A converter, 7 is a feed motor, 8 is a spindle motor, 9 is a drive circuit, 10 is a servo circuit, 11 is a system controller, 12 Is an optical disk.

The optical pickup 1 is a head that irradiates an optical disk 12 as a recording medium with light and takes in reflected light from the optical disk 12, and reads an RF signal (modulated data) recorded on the optical disk 12. The RF amplifier 2 amplifies the RF signal read by the optical pickup 1.

[0004] The decoder / signal processing circuit 3 is provided so as to be communicable with the system controller 11 for processing sub-codes and the like. The decoder / signal processing circuit 3 demodulates the RF signal passed through the RF amplifier 2 and converts it into music data. The data is subjected to predetermined processing such as error correction. Memory controller 4
Controls the write operation and the read operation of the memory 5 used when the decoder / signal processing circuit 3 performs predetermined processing such as error correction according to the instruction of the system controller 11. In the D / A converter 6, the music data is converted to analog.

The feed motor 7 is a motor for moving the optical pickup 1 in the radial direction of the optical disk 12. The spindle motor 8 is a motor for rotating the optical disc 12. The drive circuit 9 is a circuit that supplies power to the feed motor 7, the spindle motor 8, and a drive device that drives each of the objective lenses 1a in the optical pickup 1 in order to operate the drive device.

The servo circuit 10 controls each of the above-described devices driven by the drive circuit 9 so that the operation of causing the light emitted from the optical pickup 1 to follow a target track on the optical disk 12 is performed accurately. The feedback control circuit determines a control amount based on the output of the RF amplifier 2 in accordance with an instruction from the system controller 11, and outputs the control amount to the drive circuit 9 as a control signal. The system controller 11
This is a microcomputer that centrally manages the decoder / signal processing circuit 3, the memory controller 4, and the servo circuit 10.

[0007] The CD reproducing apparatus controls the rotation of the spindle motor 8 so that the rotation speed of the optical disk 12 is about 5 at normal speed.
This is a constant linear velocity method that changes from 00 rpm (inner circumference) to 200 rpm (outer circumference). However, although the linear velocity is constant for one optical disk, the optical disk is manufactured so that the linear velocity is 1.2 m / s to 1.4 m / s according to the standard. The constant value of the speed is different.

[0008] The difference in the linear velocity (a constant value of the linear velocity) between the optical disks affects the search speed. This is because, when searching, the number of tracks to the target is obtained, but the number of tracks differs depending on the linear velocity.

In order to determine the number of tracks to the target, a table (in which the target address and the number of tracks to the target are stored in association with each other) is often used. For example, a table is prepared with a linear velocity of 1.2 m / s. In this case, if an optical disk having a linear velocity of 1.4 m / s is mounted, the error in the number of tracks to the target increases (in this case, the error becomes smaller than the actual number of tracks to the target). ), A search is made for a position deviated from the target (in this case, on the inner side of the target), and the search speed is reduced.

Therefore, in order to improve the search speed, the linear velocity must be measured, and the table must be switched or the data stored in the table must be corrected according to the result.

Conventionally, there are various methods for measuring the linear velocity. One of the methods is to perform a kick (moving the objective lens 1a in the pickup 1) in the outer peripheral direction by a fixed number of tracks. There is a method in which the number of frames between these absolute addresses is calculated from the absolute address before kicking (through time from the first frame) and the absolute address after kicking, and the linear velocity is obtained based on the number of frames.

This is characterized in that the linear velocity can be measured relatively accurately without requiring a special circuit.
The processing operation performed by the system controller 11 when measuring the linear velocity by this method will be described with reference to the flowcharts shown in FIGS. The flowchart of FIG. 5 shows an initial operation from when the optical disk 12 is mounted to when a target is searched.

First, when the optical disk 12 is loaded (#
The Y, 505, rotation, focusing, and tracking servo systems are turned on (# 510). When each servo is applied, the TOC information written in the lead-in area located at the innermost circumference of the optical disk 12 and in which the absolute address is not written is read (# 515).

When the reading of the TOC information is completed (# 5)
20) The player escapes from the lead-in area, kicks in the outer peripheral direction to reach the program area where data exists and is located at a position following the lead-in area (# 525). Kick is performed until the player escapes from (# 530). When the vehicle escapes from the lead-in area (N in # 530), the linear velocity is measured (# 53).
5). Then, the number of tracks from the table corresponding to the measured linear velocity to the target (in this case, the head of the first music piece) is obtained and searched (# 540).

FIG. 6 is a flowchart showing the processing operation of measuring the linear velocity (# 535) in FIG. First, the absolute address (A ₁ min B ₁ second C ₁ frame) of the current position is read stores (# 605). Next, the kick only the outer peripheral direction a predetermined number of tracks (# 610), the absolute address of the position reached by the kick (A ₂ min B ₂ seconds C ₂ frame)
Is read and stored (# 615).

Next, from the stored absolute address before the kick and the absolute address after the kick, the number of frames between the absolute addresses is calculated by the following equation (1) (#
620).

(A ₂ × 60 × 75 + B ₂ × 75 + C ₂ ) − (A ₁ × 60 × 75 + B ₁ × 75 + C ₁ ) (1) Then, from the calculated number of frames, the number of frames and the linear velocity are stored in association with each other. The linear velocity is determined in several steps using the table (# 625).

[0018]

As described above, in this linear velocity measuring method, the linear velocity is determined using a table from the actually measured (calculated) number of frames. If the absolute address before the kick is set to the minimum absolute address of 0 minutes 0 seconds 0 frame (the absolute address of the first frame of the program area), the actual address between the absolute address before the kick and the absolute address after the kick Are stored.

Therefore, as the absolute address before the kick increases, the number of tracks to be kicked is constant as the number of tracks to be kicked is constant (as the absolute address deviates from 0 minutes, 0 seconds, 0 frames), the number of calculated frames increases. The probability of erroneously making the determination becomes high. Therefore, in order to accurately determine the linear velocity, the absolute address before the kick is set to 0 minutes 0
It is necessary to escape from the lead-in area so that the second frame is set to 0 frame, that is, the absolute address becomes 0 minute 0 second 0 frame.

However, since a continuous kick is used to escape from the lead-in area, it takes time to escape from the lead-in area if the kick is performed with a small number of kicks. Do the kick. Therefore, immediately after the escape from the lead-in area, the player is located at a position considerably deviated from the absolute address 0 minute 0 second 0 frame.

Therefore, the kick is performed in the inner circumferential direction so as not to jump into the lead-in area, and the absolute address is set to 0 minutes 0
Must approach 0 frames per second. However, since the frame of the absolute address 0 minute 0 second 0 frame is adjacent to the lead-in area, it is difficult to maintain the position, and the kick in the inner circumferential direction may improve the search speed. The start of the linear velocity measurement is delayed by the time of the kick in the inner circumferential direction.
The time required for the initial operation cannot be reduced.

In order to escape from the lead-in area,
Although the number of tracks to be moved is not so accurate, there is a method of driving the feed motor 7 and using a track count for moving the pickup 1 in the radial direction of the optical disk 12 at high speed. Since it must be close to 0 seconds and 0 frames, even if the escape from the lead-in area can be performed in a short time by the track count, the kick will be performed in the inner circumferential direction after the escape, and the time required for the initial operation cannot be shortened.
Eventually, the track count cannot be used (there is no point in using the track count).

Accordingly, an object of the present invention is to provide an optical disk reproducing apparatus in which the time required for the initial operation and the search time are reduced.

[0024]

In order to achieve the above object, according to the present invention, in an optical disk reproducing apparatus of a constant linear velocity system, at the time of an initial operation, reading of TOC information written in a lead-in area is completed. After the escape from the lead-in area, a kick is performed in the outer circumferential direction by a fixed number of tracks, and the number of frames between the absolute addresses before and after the kick is calculated from the absolute address before the kick and the absolute address after the kick. The linear velocity is calculated based on the number of frames obtained by subtracting the correction value corresponding to the absolute address before the kick from the above, and the correction value is calculated based on the number of frames between the absolute address before the kick and the absolute address after the kick. Compared to the case where the absolute address before the kick is the smallest, the amount of the increase when the absolute address before the kick is not the smallest. So that is an over-time number.

As described above, the number of frames between the absolute address before the kick and the absolute address after the kick of a fixed number of tracks for measuring the linear velocity is set so that the absolute address before the kick is minimum. Since the correction is performed by calculation, the linear velocity can be accurately measured. Therefore, in order to accurately measure the linear velocity, it is not necessary to kick in the inner circumferential direction after the escape from the lead-in area so that the absolute address is minimized. Further, with this, the escape from the lead-in area can be performed by the track count.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. The processing operations performed by the system controller 11 in the CD reproducing apparatus shown in FIG. 4 when measuring the linear velocity according to the present invention are shown in the flowcharts of FIGS. 1, 2 and 3. FIG. 1 shows an initial operation from the mounting of the optical disk 12 to the search for a target.
First, when the optical disk 12 is loaded (# 105), the rotation, focusing, and tracking servo systems are turned on (# 110).

When each servo is activated, the TOC information written in the lead-in area located at the innermost circumference of the optical disk 12 and having no absolute address written therein is read (# 115). When the reading of the TOC information is completed (#
120, Y), the track escapes from the lead-in area, and the track count is performed in the outer peripheral direction so as to reach the program area which is located at a position following the lead-in area and in which data is written (# 125).

Conventionally, kicking is performed in step # 525 in the flowchart of FIG. 5 corresponding to step # 125. However, as described later, this is performed in order to measure the linear velocity. Since the number of frames between the address and the absolute address after the kick is corrected by calculation so that the absolute address before the kick is 0 minutes, 0 seconds, and 0 frames, the absolute address is corrected to 0 minutes, 0 seconds before measuring the linear velocity. This is because there is no need to kick in the inner circumferential direction so as to approach 0 frame, and the track count can be used to escape from the lead-in area. In this way, by using the track count, the escape from the lead-in area can be performed in a shorter time.

Next, when the track escapes from the lead-in area (N in # 130), the linear velocity is measured (# 135). Then, the number of tracks from the table corresponding to the measured linear velocity to the target (in this case, the head of the first song) is obtained and searched (# 140).

The processing operation of measuring the linear velocity (# 135) in FIG. 1 is shown in the flowchart of FIG. First, the absolute address (A ₁ minute B ₁ second C ₁ frame) of the current position is read and stored (# 205). Next, track 6
It performed 0 This kick (# 210), to read stored absolute address position reached (A ₂ min B ₂ seconds C ₂ frames) by a kick (# 215).

Next, from the stored absolute address before the kick and the absolute address after the kick, the number of frames between these absolute addresses is calculated by the above equation (1) (# 22).
0). Next, the calculated number of frames is corrected (# 22
5). Then, based on the corrected number of frames, the linear velocity is determined in five steps using a table in which the number of frames and the linear velocity shown in Table 1 below are stored in association with each other (# 230).

[0032]

[Table 1]

Here, the reason why the linear velocity is determined in five stages will be described. When searching, considering the number of tracks to the target determined according to the determined linear velocity,
The greater the distance of the target, that is, the greater the absolute address of the target, the greater the error. Therefore, the actual number of tracks from the absolute address of 0 minutes 0 seconds 0 frame to the absolute address of 75 minutes 0 seconds 0 frame (the absolute address of the last frame of the program area) is examined for each linear velocity.

First, when the linear velocities are determined in three stages, the results are as shown in Table 2 below. Since the error becomes the largest when an optical disk having a linear velocity intermediate between the determined linear velocities is mounted. , 1213 ÷ 2 = 606.5 ≒ 607
It becomes a book. Next, when the linear velocity is determined in five stages as in the present embodiment, the results are as shown in Table 3 below, and the maximum value of the error is 612/2 = 306. As described above, the finer the determination of the linear velocity, the smaller the error in the number of tracks. However, it is difficult to make a finer determination from the relationship with the number of kicks described later. For the above reasons, the linear velocity is determined in five stages.

[0035]

[Table 2]

[0036]

[Table 3]

Next, the reason why the number of tracks to be kicked in the measurement of the linear velocity is set to 60 will be described. Table 4 shows the actual number of frames between the absolute address before the kick and the absolute address after the kick for each number of kicks when the absolute address before the kick is 0 minutes, 0 seconds, and 0 frames.

[0038]

[Table 4]

According to Table 4, the difference in the number of frames between adjacent linear velocities is about two frames for five kicks and three to four frames for ten kicks. However, the number of frames contained in one innermost track is 8.
Since the number of kicks is 4 to 9.8, if even one of the tracks to be kicked is wrong, the determination of the linear velocity is erroneous.

Therefore, the number of tracks to be kicked is 1
In order to correctly determine the linear velocity even if this error is made, the difference in the number of frames between adjacent linear velocities must be at least 17 to 20 frames. According to Table 4, the number of kicks satisfying this is 60 or more. As the number of kicks increases, the difference in the number of frames between adjacent linear velocities increases, and the linear velocity can be determined normally, but the number of kicks increases. If this is the case, the probability of erroneous number of tracks to be kicked increases.

In addition, the pickup 1 used for a CD-ROM drive or the like is small and thin, and the objective lens 1a
The movable range is not so large and there is a limit of about 60 kicks. For the above reasons, the number of tracks to be kicked in the measurement of the linear velocity is set to 60.

FIG. 3 is a flowchart showing the processing operation of correcting the calculated number of frames (# 225) in FIG. First, the correction value I based on the absolute address before the kick
= A ₁ × 17 is calculated (# 305). Next, a correction value J of the absolute address before the kick in seconds = (B ₁ /10)×2.83 is calculated (# 310).

Next, the correction value K = (I + J) corresponding to the absolute address before the kick is calculated by rounding off the first decimal place (# 315). Then, a value obtained by subtracting K from the number of frames calculated in # 220 in FIG. 2 is set as a corrected number L of frames (# 320). It should be noted that correcting the number of frames by calculation as described above can be performed in an extremely short time.

Here, the absolute address before the kick is set to 0 minutes 0 by the correction value K corresponding to the absolute address before the kick.
The reason why the number of frames is corrected to be 0 frames per second will be described. Table 5 shows how the actual number of frames between the absolute address before the kick and the absolute address after the kick by the 60 kicks changes depending on the absolute address before the kick.

[0045]

[Table 5]

According to Table 5, if the absolute address before the kick is shifted by one minute, the number increases by about 17 frames regardless of the linear velocity. In this case, in order to correctly determine the linear velocity, the number of kicks is set to 60 and the difference in the number of frames between adjacent linear velocities is set to 17 to 20 frames. However, there is a high possibility that the determination of the linear velocity is erroneous.

Therefore, paying attention to the fact that each time the absolute address before the kick shifts by one minute, the frame increases by about 17 frames regardless of the linear velocity, and every 10 seconds, 17 ÷ 6 = 2.833.
• Since the number of frames increased by 2.83 frames, the number of frames that increase when the absolute address before the kick deviates from 0 minutes, 0 seconds, and 0 frames is obtained by dividing the absolute address before the kick by A ₁ minute B ₁
When seconds C _{1 frame, {A 1 × 17 + (} B 1/10)
Integer part × 2.83} is rounded off to the first decimal place.

Therefore, the absolute address before the kick is 0
Even if 60 kicks are performed with the frame shifted from minute 0 second 0 frame, the above-mentioned ΔA ₁ × 17 + (B ₁ /
By subtracting the integer part of (10) × 2.83} rounded off to the first decimal place, the number of frames to be calculated is corrected as if 60 kicks were performed from the absolute address 0 minute 0 second 0 frame. be able to.

[0049]

According to the present invention, the number of frames between the absolute address before the kick and the absolute address after the kick for measuring the linear velocity is determined so that the absolute address before the kick is the minimum. Is corrected by calculation,
The linear velocity can be measured accurately. Therefore, in order to accurately measure the linear velocity, it is not necessary to kick in the inner circumferential direction so as to minimize the absolute address after exiting the lead-in area, so that the time required for the initial operation can be reduced. .

Further, since the escape from the lead-in area can be performed in a shorter time by performing the escape by the track count, the time required for the initial operation can be further reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart of an initial operation according to the present invention.

FIG. 2 is a flowchart of a measurement of a linear velocity according to the present invention.

FIG. 3 is a flowchart for correcting the number of frames calculated when measuring a linear velocity according to the present invention.

FIG. 4 is a block diagram of a CD reproducing apparatus.

FIG. 5 is a flowchart of a conventional initial operation.

FIG. 6 is a flowchart of conventional linear velocity measurement.

[Explanation of symbols]

 Reference Signs List 1 optical pickup 1a objective lens 2 RF amplifier 3 decoder / signal processing circuit 4 memory controller 5 memory 6 D / A converter 7 feed motor 8 spindle motor 9 drive circuit 10 servo circuit 11 system controller 12 optical disk

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/085 G11B 19/00 G11B 19/20 G11B 21/08 G11B 21/10

Claims (3)

(57) [Claims] In an optical disk reproducing apparatus of a constant linear velocity system, at the time of an initial operation, reading of TOC information written in a lead-in area is completed, and after exiting from the lead-in area, a certain number of tracks in an outer circumferential direction. A kick is performed, the number of frames between those absolute addresses is calculated from the absolute address before the kick and the absolute address after the kick, and a correction value corresponding to the absolute address before the kick is subtracted from the calculated number of frames. The linear velocity is determined based on the number of frames, and the correction value is calculated based on the number of frames between the absolute address before the kick and the absolute address after the kick, as compared with the case where the absolute address before the kick is the minimum. An optical disc reproducing apparatus characterized in that the number of frames increases when the absolute address is not the minimum. 2. Assuming that the absolute address before the kick is A ₁ minute B ₁ second C ₁ frame, the correction value is ΔA ₁ × 17
2. The optical disk reproducing apparatus according to claim 1, wherein an integer part of + (B ₁ /10)×2.83} is rounded off to the first decimal place. 3. The optical disk reproducing apparatus according to claim 1, wherein the escape from the lead-in area is performed by a track count.