JPS63168878A - Optical disk device - Google Patents

Abstract

PURPOSE:To realize a random access based on an actual disk linear speed by providing a means which compares an address that read the address of a shift position with a reference address and calculates the actual disk linear speed. CONSTITUTION:A linear speed arithmetic means set in a system control circuit 7 shifts a pickup 3 from a position of the designated absolute time by a degree equal to a prescribed number of tracks when an optical disk device is started to read the absolute time of a shift position and compares this absolute time with the reference absolute time corresponding to the shift position and set in an address table 13 which stores a track address calculated from a designated linear speed, e.g., 1.2m/s for calculation of an actual disk linear speed. Thus this actual linear speed can be used as a basis for calculation of the track jump number at the time of a random access and therefore an accurate random access is possible at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc device, and particularly to disc linear velocity detection for realizing high-speed and accurate random access.

[Prior art 1] At present, compact discs (so-called CDs) and read-only memories using compact discs (
The so-called CD-ROM (CD-ROM) employs a recording method in which the disk rotational speed is constant linear velocity (so-called CLV). According to the standard, the linear velocity is 1.2 to 1.4
It is said that a constant speed within the range of 1/S (meter/sho) is sufficient.

By the way, in a CD or CD-ROM, the absolute time (minutes, seconds, number of frames) T from the time when the trunk address (for example, the start of the inner circumference of the disk) is lost is subcoded for each fixed recording length. . It should be noted that one frame in the absolute time T is a value obtained by further dividing one frame into 1/75th. Therefore, once the linear velocity of the disk is determined, the relationship between the absolute time 'r and the position of the trunk (for example, expressed as the number of trunks X from the starting point as the distance from the starting point on the inner circumference of the disk) is determined. The relationship between this absolute time T and the number of tracks (position) /s (meter 7 seconds), the above relationship is output as 1, and the relationship is stored in a table (address table) inside the CDVC device. At the time of random access, the table is indexed and the current track position (
number of tracks from the starting point) and target track position r! 1 (the number of tracks from the starting point), and use the difference to find the number of tracks to jump to, that is, the distance to move.
It controlled the motor for driving the pickup feed.

As mentioned above, a conventional CD device or CD-RO
In the M device, random access was performed by specifying a linear velocity of 1.2 m/s without determining the linear velocity of each individual disk.

[Problems to be Solved by the Invention] If random access is performed at a uniform linear velocity of 1.2 m/s for all discs as in the conventional CDvtrll, etc., the linear velocity of the disc will be exactly 1. In the case of .2s/3, the specified linear velocity of the CD device etc. and the actual linear velocity of the disc match, so high-speed and accurate access is possible, but 1.2III
In the case of a disk other than /s, there is a problem that the calculated number of track jumps has a considerable error in relation to the actual number of tracks to be jumped to, resulting in a long access time.

An object of the present invention is to solve the above-mentioned conventional drawbacks and to obtain an optical disk device that enables high-speed and accurate random access.

Means for Solving Problem E 1 In this invention, in order to solve the above problem, when the device is started, the pickup is moved from a specified address by a predetermined number of tracks, the address at the position after movement is read, and this read address is and a reference address corresponding to the post-movement position, which has been calculated and stored in advance at the specified linear velocity, to calculate the actual disk linear velocity.

[Operation] Since the actual linear velocity of the CD or CD-ROM to be used is determined, this actual linear velocity is used as track jump rlL (number of tracks to jump to,
In other words, it can be used as the basis for calculating the distance to be moved. Therefore, the calculated number of track jumps (distance to be moved) is accurate, and high-speed and accurate random jumps are possible regardless of differences in linear velocity of individual disks.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.9 Fig. 1 is a block diagram of a CD device according to an embodiment of the present invention.
is a spindle motor, 2 is a disk, 3 is a big amplifier, 4 is a reproduction signal amplifier, 5 is a digital IJ processing circuit,
6 is a servo signal processing circuit, and 7 is a system control circuit. 8 is an audio conversion processing circuit, and a digital filter 9
, differential/analog converter 10, audio circuit 11
etc. In addition, in the case of a CD-ROM device,
In place of the audio conversion processing circuit 8, a CD-ROM circuit 12 indicated by a two-dot chain line is connected. In addition, 13 is an address table, and this 7 dress table 13 has the following:
The number T of tracks from the starting point of the disk (this is information representing the position of the track) calculated at a linear velocity of 1.2 m/s is stored.

The above-mentioned configuration shown in FIG. When the pickup 3 is moved from the specified absolute time position (i.e. specified address) by a predetermined number of tracks, the absolute time at the position after movement is read, and this read absolute time and 1.2m/
A linear velocity that calculates the actual disk linear velocity by comparing it with a reference absolute time (reference address) corresponding to the post-movement position in the address table 13 that stores the track address calculated at the specified linear velocity of s. A calculation program (linear velocity operator 1ri) is incorporated. An example of this program is shown schematically in the 70-chart in Figure fjS2.

Then, the disk linear velocity ■ detected by the above calculation is
It is stored as the linear velocity that is the basis for random access.

In the above configuration, when the CDVC device is started, as shown in FIG. Move to the lead-in area and read the TQC (Table on Condensation) information there about the contents of the disc. Next, pick up 3 for example at an absolute time of 20 minutes.
Move to a position of 0 seconds, 007 frames, and from this position, while counting the number of tracks, move exactly by (for example, 1000) ranks, read the absolute time T of the position after movement, and write this absolute time T and the address table. Compare the reference absolute time T0 corresponding to the post-movement position obtained from 13 and calculate the actual linear velocity V+++/s using the following formula, V=1,2XT,/T, ・・・・・・■ i[Find by calculation.

Then, the system control circuit 7 performs random access based on this linear velocity ■. Since this linear velocity ■ is the actual linear velocity of the disk, the number of tracks to jump calculated based on this linear velocity is Accurate. Therefore, high speed and accurate random access is realized.

In addition, during random access, when indexing the table 13 of the relationship between the absolute time T and the number of tracks Instead of using the number of tracks X directly indexed using , the number of tracks X′ obtained by multiplying the number of tracks X by a correction coefficient is used. The value of this correction coefficient is (detected linear velocity/designated linear velocity), which is V/1.2 in the example. By using this corrected accurate number of tracks (position) X' from the starting point, it is possible to accurately calculate the number of tracks to jump to.

The actual disk linear velocity calculated as above is
It can also be used to control the rotation speed of the spindle motor 1.

In the embodiment, the designated address is 20 minutes OO seconds 00 frames and the number of tracks to be counted is 1000, but it is of course not limited to these values.

In addition, in the embodiment, data in the address table 13 is used as the reference address used when calculating the linear velocity.
Separately from the address table, a reference address previously determined by calculation may be stored independently as reference address data, and this reference address data may be used when calculating the linear velocity.

Further, the track address does not necessarily have to be time data as in the embodiment, but may be any information representing the position in the track quality direction.

The present invention also applies to the current CDvcr11, CD-ROM
The present invention is not limited to these devices, but can be applied to optical disk devices having an address table storing track addresses such as absolute time calculated at a specified linear velocity.

[Effect 1 of the Invention According to the present invention as explained above,! At the time of starting the positioning, the Totsuk 7 knob is moved by a predetermined number of tracks from the specified address, the address of the post-movement position is read, and the position after the movement is calculated and stored in advance using the read address and the specified linear velocity. Since we have provided a linear velocity calculation means that calculates the actual linear velocity of the disk by comparing it with the corresponding reference address, it is possible to perform random access based on the actual linear velocity of the disk, and the linear velocity of each individual disk can be It has become possible to perform high-speed and accurate 2-band access regardless of speed differences.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a CD device showing an embodiment of the present invention, and FIG. 2 is a schematic 70-chart of a program (linear velocity calculation means) for calculating #1M degrees. 3...Pickup, 7...System control circuit, 1
3...Address table. Figure 2

Claims (1)

[Claims] In an optical disk device that has an address table that stores track addresses calculated at a specified linear velocity, when the device is started, the pickup is moved from the specified address by a specified number of tracks, and the address at the position after the movement is read.
A linear velocity calculation means is provided for calculating the actual disk linear velocity by comparing the read address with a reference address corresponding to the post-movement position, which has been calculated and stored in advance at the specified linear velocity. Characteristic optical disc device.