JPH05217279A - Clv disk reproducing device - Google Patents

Abstract

PURPOSE:To provide a linear velocity measuring device having no specific device for detecting the rotation of a CLV disk and measuring the linear velocity of the disk at a low cost on the linear velocity measuring device of a CLV disk reproducing device. CONSTITUTION:Address information being a reference decided previously on a certain track on the disk 10 is reproduced by a reading device II. When the address information is detected by an address detection device 12, time counting is started by a time measuring device 13 and simultaneously the reading device 11 is moved in the direction of a radius facing to the track inside of one track. A time till the address information is detected is measured again by the address detection device 12. The linear velocity is calculated by a linear velocity calculation device 14 based on the radius of the disk where the address information is present and the measured time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant linear velocity (CLV) disc reproducing apparatus requiring high speed access such as a CD-ROM drive, and a pickup for reading a signal from the disc at a high speed to a target point on the disc. It is characterized by a linear velocity measuring means at the time of reproduction necessary for measuring the recording intervals of the addresses recorded at equal intervals on the disc to be accessed in order to move to.

[0002]

2. Description of the Related Art In a CLV disc reproducing apparatus, a synchronizing signal and an address signal are recorded at equal intervals along a track, and at the time of reproducing, the synchronizing signal and the address signal of the disc are reproduced so as to be reproduced at a predetermined constant cycle. The rotation is controlled, and the distance between the addresses on the disk is an important parameter in calculating the number of moving tracks from the current address of the reading device to the target address. However,
The linear velocity of CLV discs is, for example, 1.2 to 1.4 m / s according to the standard for compact discs, and is not always constant between discs. Therefore, in order to access the CLV disc at high speed, it is necessary to measure the linear velocity during reproduction of the disc to be accessed, that is, the address interval.

A linear velocity measuring device of a conventional compact disc reproducing device will be described below with reference to the drawings.

FIG. 3 is a block diagram of a conventional linear velocity measuring device. In FIG. 3, 31 is a disk 30.
A reading device for reading a signal from the disk 32, a disk 30
A rotation detecting device for detecting the rotation of the disk, 33 is a time measuring device for measuring the rotation time required for the disk to rotate at a predetermined angle by a signal output from the rotation detecting device 32, and 34 is a time measuring device 33. This is a linear velocity calculation device that calculates the linear velocity of the disk 30 being reproduced based on the measured time and the radius of the reading device 31 at the current position.

The operation of the linear velocity measuring device constructed as above will be described. First, the reading device 31 is moved to the address start point on the innermost circumference of the disk 30.
The time required for the rotation of the disk is obtained by measuring the time required for the disk 30 to rotate a predetermined angle based on the signal output from the rotation detection device 32. The linear velocity of the disk being reproduced is calculated based on the radius at the address start point and the rotation time measured by the time measuring device 33.

[0006]

However, in the above-mentioned conventional configuration, as the rotation detecting device 32 for detecting the rotation of the disk, for example, a rotation detecting device combining a slit and a photo sensor, or a Hall element output is used. There is a problem in that a device having a special hardware configuration such as a rotation detection device using a provided disk drive motor is required, and the cost of the CLV disk reproducing device increases accordingly.

The present invention solves the above-mentioned problems of the prior art, and does not have any special device for detecting rotation.
It is an object of the present invention to provide a CLV disk reproducing device that can inexpensively measure the linear velocity of a disk.

[0008]

In order to solve the above-mentioned problems, the CLV disk reproducing apparatus of the present invention, when reproducing a CLV disk in which addresses are sequentially added at equal intervals on a track, the distance from the center of rotation is Detects a reference address that is known in advance, moves the reading device toward the track located upstream of the reference address by a specified number of tracks in the radial direction of the disc, and reproduces from the movement point to the reference address. The feature is that the required time is measured and the linear velocity at the time of reproduction is calculated from the required time and the measured distance.

[0009]

In the above structure, first, the reading device is moved to the track at a predetermined position. While the reading device follows the track while reading the signal recorded on the disc, the address detecting device detects the address information serving as a predetermined reference. After the reference address information is detected, the reader is moved inward by N tracks. While the reading device tracks and reproduces the track, the address detecting device detects the reference address information again. The time required for the rotation of the disk can be obtained by measuring the time from when the reference address information is first detected until it is detected again by the time measuring device. The linear velocity of the CLV disc being reproduced is calculated based on the radius of the track on which the reference address information exists and the rotation time of the disc measured by the time measuring device.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram of a linear velocity measuring device of a compact disc reproducing device. In FIG. 1, 11 is a reading device that reads a signal from the disc 10, and 12 is a disc 1 that is read from the signal read by the reading device 11 in synchronization with a synchronization signal recorded on the disc 10.
An address detecting device for detecting address information of 0, 13 is a time measuring device for measuring time required for the rotation of the disk, 14
Is a linear velocity calculating device for calculating the linear velocity of the disc 10 being reproduced based on the time required for the disc to rotate and the radius of the reading device 11 at the current position.

The operation of the linear velocity measuring device constructed as above will be described with reference to FIG. FIG. 2 is a schematic diagram of the disk 10. Address information A is recorded on each track for each frame, and one address information A on a track at a position of radius r1 is used to measure the rotation time of the disk 10. Measurement reference address A0 for
Is determined in advance.

First, the reading device 11 is moved slightly before the measurement reference address A0 of the disk 10. While the reading device 11 follows the track while reading the signal recorded on the disk 10, the address detecting device 12
Detects the measurement reference address A0. Measurement address A0
At the same time as the detection of
Further, the reading device 11 is moved in the inner circumferential direction so that the reading device 11 reproduces a track located one track inside (upstream side) from the track of the measurement reference address A0. As the reading device 11 follows the inner track, the address detection device 12 detects the measurement reference address A0 again. At this point, the time measurement of the time measuring device 13 is finished.
The time required for the disk to rotate can be obtained by measuring the time from when the address detection device 12 first detects the measurement reference address A0 until it is detected again by the time measurement device 13. The radius r1 at the reference address A0,
The linear velocity calculation device 14 calculates the linear velocity of the disc being reproduced based on the rotation time measured by the time measuring device 13.
Calculate with. In the CLV disc reproducing apparatus, since the synchronizing signal (address signal) is controlled by the disc linear velocity so as to be reproduced at a predetermined cycle as described above,
When the linear velocity is known, the address signal interval can be calculated.

Since the address detecting device 12 and the time measuring device 13 for measuring the rotation time of the disk 10 can be realized by a microcomputer, a special device conventionally required for measuring the rotation time. It is possible to obtain a CLV disc reproducing apparatus which is inexpensive and is miniaturized without requiring the above.

If the above-mentioned measurement reference address A0 is set near the innermost track r0 defined by the standard on the disk 10, the variation in the radius caused by the variation in CLV is small. The measurement error can be reduced. Further, in this embodiment, the reading device 11 is moved to one inner track after the measurement reference address A0 is detected. However, the number of tracks moved is N, and the disk rotates N times. By measuring the time, it is possible to suppress variations in the rotation time per disk revolution,
The accuracy can be further increased. Further, when the disk address A0 cannot be detected due to a scratch on the disk or the like, a spare measurement reference address is provided, and the rotation time is measured at the spare measurement reference address. It is possible to avoid an unmeasurable state.

[0015]

As described above, according to the present invention, the linear velocity is calculated by detecting the rotation of the CLV disc by using the reading device and the address detecting device originally installed in the CLV disc to calculate the linear velocity. It is possible to measure the linear velocity of a CLV disc with high accuracy without adding a device having a special hardware configuration for detecting rotation, and to reduce the cost of the CLV disc reproducing device. It is possible to realize an excellent linear velocity measuring device that contributes to miniaturization.

[Brief description of drawings]

FIG. 1 is a block diagram of a linear velocity measuring device according to an embodiment of the present invention.

FIG. 2 is a CL for explaining an operation in the embodiment of the present invention.
Schematic diagram of V disk

FIG. 3 is a block diagram of a conventional linear velocity measuring device.

[Explanation of symbols]

 11, 31 reading device 12 address detecting device 13, 33 time measuring device 14, 34 linear velocity calculating device 32 rotation detecting device

Claims (1)

[Claims] 1. When reproducing a CLV disc in which addresses are sequentially assigned at equal intervals on a track, a reference address whose distance from a rotation center is known in advance is detected, and the reference address is located upstream of the reference address. Move the reading device toward the track in the radial direction of the disc by a specified number of tracks, measure the required playback time from the moving point to the reference address, and then determine the linear velocity during playback from the required time and the measured distance. CLV characterized by calculating
Disc player.