JPH08167155A - Optical disk reproducing device - Google Patents

Abstract

PURPOSE: To provide an optical disk reproducing device capable of suppressing the occurrence of a read error by limiting the number of tracks traversed in a once jump according to the occurrence rate of the read error. CONSTITUTION: Information read by an optical head 103 is demodulated to a digital signal by a demodulater 105 after being amplified by an RF amplifier. Although the read error occurs when a scratch or dust is stuck on an optical disk 101, the read error is detected and corrected by an ECC 111. The occurrence frequency (or error rate) of the read error is measured by an error frequency measurement circuit 121, and the occurrence of the state becoming tracking impossibility is prevented by the fact that the more reducing the number of upper limit jumps decided by a jump control circuit 123 the more the occurrence frequency of the read error becomes large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc reproducing apparatus, and more particularly to an optical disc reproducing apparatus capable of suppressing the occurrence of reading errors.

[0002]

2. Description of the Related Art Optical discs, represented by compact discs (CDs), are widely used as random-accessible audio, navigation systems or mass storage devices for computers. Then, in order to realize random access, a jump operation for jumping over multiple tracks at once is required, but conventionally, the difference between the track currently being picked up by the pickup and the target track is judged to make one or more jumps. Was going on.

[0003]

However, the jump is performed by moving the optical disk and the pickup relatively in the radial direction of the optical disk.
When the number of tracks to be skipped by one jump is large, it is inevitable that the distance from the optical axis facing the currently traced track to the target track becomes large and the read error rate increases.

Particularly in the case of an optical disk having scratches or dust, reading errors frequently occur, and in the worst case, access cannot be performed normally. The present invention has been made in view of the above problems, and an optical disk reproducing apparatus capable of suppressing the occurrence of a read error by limiting the number of tracks jumped in one jump according to the rate of occurrence of a read error. The purpose is to provide.

[0005]

According to a first aspect of the present invention, there is provided an optical disc reproducing apparatus in which an optical pickup is moved in a radial direction of the optical disc within a range from one track of the optical disc to a predetermined upper limit number of tracks in response to a jump command. Jumping means for jumping, error occurrence frequency measuring means for measuring error occurrence frequency per fixed time when reading data,
Upper limit track number limiting means for decreasing the upper limit track number of the jump means as the error occurrence frequency measured by the error occurrence frequency measuring means becomes higher.

An optical disk reproducing apparatus according to a second aspect of the present invention comprises jump means for causing the optical pickup to jump in the radial direction of the optical disk within a range from one track of the optical disk to a predetermined upper limit number of tracks in response to a jump command. Error rate measuring means for measuring the ratio of erroneous data to the number of data read at the time of data reading, and upper limit track number limiting means for decreasing the upper limit track number of the jump means as the error rate measured by the error rate measuring means increases, It is equipped with.

[0007]

In the optical disc reproducing apparatus according to the first aspect of the present invention, the higher the error occurrence frequency for a certain period of time, the smaller the upper limit number of tracks jumped by one jump.
In the optical disc reproducing apparatus according to the second invention,
The higher the error rate, which is the ratio of error data to the number of read data, is, the smaller the upper limit number of tracks jumped in one jump is.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a compact disc reproducing apparatus, which is a compact disc (hereinafter referred to as a CD) 1.
01 is driven to rotate by the spindle motor 102. The information recorded on the CD is the optical head 103.
Is read by the RF amplifier 104, amplified by the RF amplifier 104, and then demodulated into a digital signal by the demodulator 105.

The output of the RF amplifier 104 is RFPLL10.
6 is also supplied to 6 to regenerate the clock, which clock is transmitted via the spindle servo 107 to the spindle motor 10
The rotation speed of 2 is changed to control the linear speed at the time of reading information to be constant. The output of the RF amplifier 104 is also supplied to the tracking / focus servo 108 to drive an actuator (not shown) incorporated in the optical head 103 to control tracking and focus.

Further, the tracking signal drives the sled feed motor 110 via the slide drive circuit 109,
The optical head 103 is moved in the radial direction of the CD 10. The digital signal demodulated by the demodulator 105 is subjected to error detection / correction (hereinafter referred to as ECC) 111 to detect and correct error data, which is then converted into an analog signal by the D / A converter 112 and amplified by the audio amplifier 113. Is output.

The operation of the compact disc reproducing apparatus is controlled by a control unit 12 composed of a microcomputer. The control unit 12 has an error frequency measuring circuit 12
1. Jump switch 122 and jump control circuit 1
Includes 23. That is, when the jump switch 122 is turned on, the jump control circuit 123 determines the number of jump tracks and supplies it to the tracking drive circuit 108. Then, by the output from the tracking drive circuit 108, an objective lens (not shown) that is elastically supported in the optical head 103 and driven by the electromagnetic circuit.
The tracking actuator including the sled feed motor 110 is driven via the slide drive circuit 109 to execute a jump of a predetermined number of tracks equal to or less than the upper limit number of tracks.

The jump is generated not only when the jump switch 122 is turned on, but also by a jump signal sent from another device. The error frequency measuring circuit 121 uses the ECC 11 that is generated within a fixed time.
Each time 1 detects and corrects an error, it counts the number of error signals EC output. The error signal number EC is sent to the jump control circuit 123, and the upper limit track number is determined according to the error signal number EC.

FIG. 2 is a graph for determining the maximum number of tracks, in which the horizontal axis represents the number of error signals EC and the vertical axis represents the maximum number of tracks. That is, when the number of error signals EC exceeds a certain level, the upper limit number of tracks decreases as the number of error signals EC increases. Instead of the error frequency measuring circuit 121, an error rate measuring circuit that measures the ratio of the error signal number EC to the read data number may be used.

[0014]

According to the optical disk reproducing apparatus of the first aspect of the present invention, scratches or dust are reduced by reducing the upper limit number of tracks jumped in one jump as the error occurrence frequency for a certain time increases. It is possible to prevent the tracking from becoming impossible even when reading the optical disc attached to the.

According to the optical disk reproducing apparatus of the second invention, the higher the error rate, which is the ratio of the error data to the number of read data, the smaller the upper limit number of tracks jumped in one jump becomes. Tracking failure can be prevented even when reading an optical disk with scratches or dust.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a compact disc reproducing device.

FIG. 2 is a graph for determining the maximum number of tracks.

[Explanation of symbols]

 101 ... Compact disk 102 ... Spindle motor 103 ... Optical head 104 ... RF amplifier 105 ... Demodulator 106 ... RFPLL 107 ... Spindle servo 108 ... Tracking / focus servo 109 ... Slide drive circuit 110 ... Tread feed motor 111 ... ECC 112 ... D / A converter 113 ... Audio amplifier 12 ... Control unit 121 ... Error frequency measuring circuit 122 ... Jump switch 123 ... Jump control circuit

Claims (2)

[Claims] 1. An optical disc 1 in response to a jump command.
In an optical disc reproducing apparatus equipped with jumping means for causing an optical pickup to jump in the radial direction of an optical disc within a range from a track or more to a predetermined upper limit number of tracks or less, an error occurrence frequency measurement for measuring an error occurrence frequency per constant time during data reading And an upper limit track number limiting unit for decreasing the upper limit number of tracks of the jump unit as the error occurrence frequency measured by the error occurrence frequency measuring unit becomes higher. 2. An optical disc 1 in response to a jump command.
An error rate for measuring the ratio of error data to the number of data read at the time of data reading in an optical disk reproducing apparatus equipped with jumping means for jumping the optical pickup in the radial direction of the optical disk within a range from a track to a predetermined upper limit number of tracks An optical disk reproducing apparatus further comprising: a measuring unit; and an upper limit track number limiting unit that reduces the upper limit number of tracks of the jump unit as the error rate measured by the error rate measuring unit increases.