JP3956147B2 - Optical disk playback device - Google Patents

Description

  The present invention relates to an optical disc reproducing apparatus for reproducing information from an optical disc such as a CD or a DVD.

  Conventionally, an optical disk reproducing apparatus reads information recorded on an optical disk by irradiating the optical disk with an optical head and receiving reflected light from the optical disk while rotating the optical disk at high speed by a spindle motor. It has become. Information is recorded on the optical disc by an array of pits that cause reflection of light different from the surroundings, and the optical head outputs a signal at a voltage level corresponding to the received light intensity, that is, the reflected light intensity from the optical disc, as a read signal. It has become. Accordingly, the received light intensity of the optical head changes according to the presence or absence of pits as the optical disk rotates, and the read signal output from the optical head is an RF (Radio Frequency) signal having a high frequency component.

  Then, the optical disk reproduction device decodes the read signal (RF signal) output from the optical head to generate a video signal and an audio signal, and outputs the video signal and the audio signal to the display and the speaker, thereby generating an optical disk. Information such as video and audio recorded in the video is reproduced. At this time, the optical disc reproducing apparatus detects an error included in the read signal, corrects the error, and decodes the corrected signal to generate a video signal and an audio signal. However, if there are many errors included in the read signal, information cannot be reproduced stably.

  Therefore, in such an optical disk reproducing device, in order to reduce errors included in the read signal, the read signal is boosted by an equalizer and a noise frequency component included in the read signal is cut off to equalize the read signal waveform. Processing to do.

  The optimum values for the boost amount and cut-off frequency of the equalizer vary depending on conditions such as the difference in the rotation speed of the optical disc, mounting variation, the difference in reflectance due to the optical disc, the tilt shift, the difference in light emission intensity and light reception sensitivity of the optical head, etc. Depends on the position on the optical disc.

In the conventional optical disk reproducing apparatus, the cutoff frequency of the equalizer is variably set in accordance with the reproduction speed during the optical disk reproducing operation (see, for example, Patent Document 1), or the optical disk is rotated before the optical disk reproduction is started. There are known ones that are variably set according to the speed (for example, see Patent Document 2), and those that are variably set based on the jitter value of the read signal output from the optical head before reproduction of the optical disk is started (for example, Patent Document 2). 3). Also, the equalizer boost amount is variably set based on the jitter value of the read signal output from the optical head before the reproduction of the optical disk (see, for example, Patent Document 1 and Patent Document 3), or the reproduction of the optical disk. One that is variably set based on the error frequency of the read signal output from the optical head before the start is known (see, for example, Patent Document 1).
JP-A-10-214458 JP 2004-227697 A JP 2002-8243 A

  However, in the above-described conventional optical disc reproducing apparatus, the boost amount of the equalizer is fixed to a constant value during the reproducing operation of the optical disc, that is, during the reading operation of information from the optical disc by the optical head. For this reason, during the information reading operation, if the light emission intensity or light receiving sensitivity of the optical head changes due to a temperature change or the like, or the optical disk reading position changes and the optical disk reflectivity changes, the equalizer boost amount is optimal. The read signal output from the optical head could not be properly equalized by the equalizer.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical disc reproducing apparatus that can optimize the waveform equalization processing of a read signal by an equalizer.

  In order to achieve the above object, the invention of claim 1 is directed to receiving a reflected light from the optical disk by irradiating the optical disk rotated by the spindle motor mounted with the optical disk and the optical disk rotated by the spindle motor. The optical head that reads information from the optical disk and outputs a read signal with a voltage level corresponding to the received light intensity, boosts the read signal output from the optical head, and cuts off the noise frequency component contained in the read signal An equalizer for equalizing the waveform of the read signal, an error correction means for detecting an error included in the read signal after the waveform is equalized by the equalizer, and correcting the error, and the waveform is equalized by the equalizer The jitter value measuring means for measuring the jitter value of the read signal after being read and the error detection rate by the error correcting means are measured. A rate measuring means, an equalizer setting means for variably setting an equalizer boost amount and a cut-off frequency based on a jitter value measured by the jitter value measuring means and an error detection rate measured by the error rate measuring means, and an optical disk by a spindle motor Disk rotation control means for controlling the rotation so that the rotation linear velocity at the information reading position by the optical head of the optical disc is constant or CAV rotation at which the rotational angular velocity of the optical disc is constant. In the optical disc reproducing apparatus, the equalizer setting means changes the equalizer boost amount to several values, measures the jitter value by the jitter value measuring means, and measures the error detection rate by the error rate measuring means, and measures these. Equalizer boost amount based on jitter value and error detection rate Boost amount setting means to set the optimum value, change the cutoff frequency of the equalizer to several values, measure the jitter value by the jitter value measuring means and measure the error detection rate by the error rate measuring means, Cut-off frequency setting means for setting the equalizer cut-off frequency to an optimum value based on the measured jitter value and error detection rate. During the reading operation of information from the optical disk by the optical head, a predetermined address is set. When the rotation of the optical disk by the disk rotation control means is CLV rotation, the boost amount is set by the boost amount setting means, and when the rotation of the optical disk by the disk rotation control means is CAV rotation, In addition to setting the boost amount by the amount setting means, the cutoff frequency by the cutoff frequency setting means It is for setting.

  According to the first aspect of the invention, the boost amount of the equalizer is equal to a predetermined address during an operation of reading information from the optical disk, regardless of whether the optical disk is rotated at a constant linear velocity CLV rotation or a constant angular velocity CAV rotation. Each time the information is read, the optimum value is variably set based on the jitter value of the read signal and the ratio of errors contained in the read signal. Therefore, regardless of whether the optical disk is rotated by CLV rotation or CAV rotation, the light emission intensity or light receiving sensitivity of the optical head changes due to a temperature change or the like during the optical disk reading operation, or the optical disk reading position changes. Even if the reflectance changes, the equalizer boost amount can be maintained at an optimum value, and the lead quality can always be kept high. In addition, when the optical disk is rotated by CAV, the equalizer cutoff frequency also includes the jitter value of the read signal and the error included in the read signal each time information for a predetermined address is read during the information reading operation from the optical disk. Is variably set to an optimal value based on the ratio. Accordingly, even when the optical disk is rotated by CAV and the reading speed of the optical disk changes and the frequency component of the read signal output from the optical head changes, the equalizer cutoff frequency can be maintained at an optimum value. As a result, the lead quality can always be kept high.

  Hereinafter, an optical disk reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of an optical disc playback apparatus. The optical disc playback device 1 is a device that plays back information such as video and music from an optical disc 2 such as a CD or DVD.

  The optical disk reproducing apparatus 1 includes a control unit 11 including a CPU for controlling the optical disk reproducing apparatus 1, a spindle motor 12, a seek motor 13, an optical head 14, an equalizer 15, a demodulation processing unit 16, and an error A correction processing unit 17, a decoding processing unit 18, a jitter value measuring unit 19, a BLER (block error rate) measuring unit 20, a remote controller 21, a remote control receiving unit 22, and a ROM 23 are provided.

  The spindle motor 12 is loaded with the optical disk 2 and is rotated under the control of the control unit 11 to rotate the optical disk 2. The seek motor 13 is composed of a linear motor, and moves the optical head 14 in the radial direction of the optical disc 2 (seek operation) under the control of the control unit 11.

  The optical head 14 reads information recorded on the optical disc 2 by irradiating the optical disc 2 rotated by the spindle motor 12 under the control of the control unit 11 and receiving the reflected light. The optical head 14 outputs a signal having a voltage level corresponding to the received light intensity, that is, the reflected light intensity from the optical disk 2, to the control unit 11 as a read signal. On the optical disc 2, recording tracks are formed concentrically or spirally at a predetermined pitch, and pits that cause reflection of light different from the surroundings are arranged on the recording track to record information. Accordingly, the received light intensity of the optical head 14 changes according to the presence or absence of pits as the optical disk 2 rotates, and the read signal output from the optical head 14 is an RF (Radio Frequency) signal having a high frequency component. .

  The equalizer 15 boosts the read signal output from the optical head 14 and cuts off a noise frequency component included in the read signal to equalize the read signal waveform. The equalizer 15 is configured to variably set a boost amount for boosting the read signal and a cut-off frequency for cutting off a noise frequency component included in the read signal under the control of the control unit 11. Details of the variable setting of the boost amount and the cutoff frequency will be described later. The demodulation processing unit 16 demodulates the read signal after the waveform is equalized by the equalizer 15.

  The error correction processing unit 17 checks the read signal after the waveform is equalized by the equalizer 15 and demodulated by the demodulation processing unit 16, detects an error included in the read signal, and corrects the error. Based on the signal after the error is corrected by the error correction processing unit 17, the decoding processing unit 18 reproduces a video signal and audio for reproducing the video on a display (not shown) and a speaker (not shown). For generating an audio signal. The video signal and the audio signal generated by the decoding processing unit 18 are output to the display and the speaker via the signal output terminal 18a, whereby the video and audio recorded on the optical disc 2 are reproduced on the display and the speaker. Is done.

  The jitter value measuring unit 19 measures the jitter value of the read signal after the waveform is equalized by the equalizer 15. The BLER measurement unit 20 measures the error detection rate of the read signal by the error correction processing unit 17. The recording track of the optical disc 2 is composed of a large number of sectors, and one block is composed of a plurality of sectors. The BLER measurement unit 20 measures an error detection rate (block error rate) in units of blocks.

  The remote controller 21 is operated by a user in order to instruct various operations of the optical disc playback apparatus 1 such as playback of information from the optical disc 2. The remote controller 21 is provided with various operation keys operated by the user to instruct various operations of the optical disc playback apparatus 1, and when the various operation keys are operated, an infrared signal associated with the operation is transmitted. To do. The remote control receiving unit 22 receives an infrared signal transmitted from the remote control 21 and converts it into an electrical signal, and outputs a signal corresponding to the operation of the remote control 21 to the control unit 11. The ROM 23 stores an operation program for the control unit 11.

  The control unit 11 determines an instruction content by operating the remote controller 21 based on an output signal from the remote control receiving unit 22, and performs an operation for reproducing information from the optical disk 2 in accordance with the operation of the remote controller 21. Control various operations. Information reproduction from the optical disk 2 is performed by reading information from the optical disk 2 by the optical head 14, performing waveform equalization processing by the equalizer 15 on the read signal output from the optical head, demodulating it by the demodulation processing unit 16, and correcting errors. This is performed by generating a video signal and an audio signal in the decoding processing unit 18 after correcting the error in the processing unit 17. Reading of information from the optical disk 2 by the optical head 14 is performed by rotating the optical disk 2 by the spindle motor 12 and irradiating the optical disk 2 with the optical head 14 to receive reflected light.

  The control unit 11 includes a disk rotation control unit 31 that controls the rotation of the optical disk 2 by the spindle motor 12, and an equalizer setting unit 32 that variably sets the boost amount and cutoff frequency of the equalizer 15.

  The disk rotation control unit 31 controls the rotation of the optical disk 2 by the spindle motor 12 so that the rotation of the optical disk 2 is CLV rotation or CAV rotation in the information reading operation from the optical disk 2 by the optical head 14. The CLV rotation is a rotation that makes the rotation linear velocity at the information reading position of the optical head 2 of the optical disc 2 constant, and the CAV rotation is a rotation that makes the rotation angular velocity of the optical disc 2 constant. The rotation method of the optical disc 2 in the reading operation is appropriately selected as either CLV rotation or CAV rotation depending on the recording form of information recorded on the optical disc 2 or the like. The disk rotation control unit 31 detects the rotation speed of the optical disk 2 based on the read signal output from the optical head 14 and controls the rotation of the optical disk 2 so as to be CLV rotation or CAV rotation.

  The equalizer setting unit 32 variably sets the boost amount and cut-off frequency of the equalizer 15 based on the jitter value measured by the jitter value measuring unit 19 and the block error rate measured by the BLER measuring unit 20. In setting the boost amount by the equalizer setting unit 32, the boost amount of the equalizer 15 is changed to several values, and the jitter value and block error rate measured by the jitter value measuring unit 19 and the BLER measuring unit 20 at that time are changed. Based on this, the boost value is set so that the jitter value and the block error rate are optimized. Further, the setting of the cut-off frequency by the equalizer setting unit 32 is performed by changing the cut-off frequency of the equalizer 15 to several values, and at that time the jitter value measured by the jitter value measuring unit 19 and the BLER measuring unit 20 and Based on the block error rate, it is performed by setting a cutoff frequency at which the jitter value and the block error rate are optimal.

  The equalizer setting unit 32 sets the boost amount and the cut-off frequency at predetermined intervals during the operation of reading information from the optical disk 2 by the optical head 14. In each sector constituting the recording track of the optical disc 2, an address for identifying each sector is recorded in advance by pits. The equalizer setting unit 32 detects the address of the sector from which the information is read by the optical head 14 based on the read signal output from the optical head 14, and each time information corresponding to a predetermined address is read by the optical head 14, Set boost amount and cutoff frequency. The equalizer setting unit 32 variably sets only the boost amount when the rotation of the optical disc 2 is CLV rotation, and variably sets both the boost amount and the cutoff frequency when the rotation of the optical disc 2 is CAV rotation.

  FIG. 2 shows a flowchart of the information reading operation from the optical disc 2 including the setting operation of the boost amount and cut-off frequency of the equalizer 15 of the optical disc reproducing apparatus 1. When the reproduction start instruction is given by the remote controller 21 (YES in # 1), the control unit 11 rotates the optical disc 2 by the spindle motor 12 and irradiates the optical disc 2 with light from the optical head 14 so that the optical head 14 Reading of information from the optical disc 2 is started (# 2).

  When the rotation of the optical disk 2 is CLV rotation (YES in # 3), the control unit 11 sets the boost amount of the equalizer 15 as a default value, measures the jitter value by the jitter value measurement unit 19, and performs the BLER measurement. The block 20 measures the block error rate (BLER) and stores the measured value (# 4). Subsequently, the control unit 11 changes the boost amount of the equalizer 15 to several values (for example, increases or decreases by 1 to 2% in three steps from the default value), and the jitter value measurement unit 19 performs the jitter value. And the BLER measurement unit 20 measures the BLER and stores the measured values (# 5). Then, the control unit 11 sets the boost amount of the equalizer 15 to the boost amount when the jitter value and BLER are optimum among the measured jitter value and BLER (# 6). Thereby, the boost amount of the equalizer 15 is set to an optimum value.

  If the rotation of the optical disk 2 is not CLV rotation, that is, CAV rotation (NO in # 3), the control unit 11 sets the cutoff frequency of the equalizer 15 as a default value and the jitter value measurement unit 19 performs the jitter value. And the BLER measurement unit 20 measures the BLER and stores the measured value (# 7). Subsequently, the control unit 11 changes the cutoff frequency of the equalizer 15 to several values (for example, increases or decreases by 0.1 to 0.2 Hz from the default value in three stages), and the jitter value measurement unit 19. The jitter value is measured by the BLER and the BLER measurement unit 20 measures the BLER and stores the measured value (# 8). Then, the control unit 11 sets the cutoff frequency of the equalizer 15 to the cutoff frequency at which the jitter value and BLER are optimum among the measured jitter value and BLER (# 9). Thereby, the cut-off frequency of the equalizer 15 is set to an optimum value. Thereafter, the control unit 11 performs the processes of # 4 to # 6 to set the boost amount of the equalizer 15 to an optimal value.

  After the process of # 6, the control unit 11 continues reading information from the optical disc 2 (# 10), and reads information for a predetermined address (for example, 10,000 addresses) from the optical disc 2 (YES in # 11). ), The above-described processing after # 3 is repeated. Thus, every time information for a predetermined address is read during the reading operation of information from the optical disc 2, the boost amount is variably set to an optimum value when the rotation of the optical disc 2 is CLV rotation, and the rotation of the optical disc 2 is changed. In the case of CAV rotation, in addition to the boost amount, the cutoff frequency is variably set to an optimum value.

  While the processes from # 3 to # 11 are repeated, information corresponding to a predetermined address cannot be read from the optical disk 2 (NO in # 11), and an instruction to stop reproduction is given by the remote controller 21 (YES in # 12). When reading of all information from 2 is completed (YES in # 13), the control unit 11 finishes reading information from the optical disc 2 (# 14).

  According to the optical disc playback apparatus 1 having such a configuration, the boost amount of the equalizer 15 is determined based on the information from the optical disc 2 regardless of whether the optical disc 2 is rotated at a constant linear velocity CLV rotation or an angular velocity constant CAV rotation. Each time information corresponding to a predetermined address is read during the reading operation, the optimum value is variably set based on the jitter value of the read signal and the ratio of errors contained in the read signal. Therefore, regardless of whether the optical disk 2 is rotated by CLV rotation or CAV rotation, the light emission intensity or light receiving sensitivity of the optical head 14 changes due to a temperature change or the like during the reading operation of the optical disk 2, or the reading position of the optical disk 2 changes. Even if the reflectivity of the optical disc 2 changes, the boost amount of the equalizer 15 can be maintained at an optimum value, and the read quality can always be kept high.

  In addition, when the optical disk 2 is rotated by CAV, the cutoff frequency of the equalizer 15 is also changed to the jitter value of the read signal and the read signal each time information for a predetermined address is read during the information reading operation from the optical disk 2. It is variably set to an optimal value based on the ratio of errors included. Therefore, even when the reading speed of the optical disc 2 changes and the frequency component of the read signal output from the optical head 2 changes when the optical disc 2 is rotated by CAV, the cutoff frequency of the equalizer 15 is maintained at an optimum value. And lead quality can always be kept high.

  In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible. For example, in the above embodiment, the variable setting of the boost amount and the cut-off frequency of the equalizer 15 is not limited every time information corresponding to a predetermined address is read from the optical disc 2, for example, every time a predetermined time elapses and every optical head moving distance. You may make it perform. The boost amount and cut-off frequency of the equalizer 15 are variably set based on either the jitter value measured by the jitter value measuring unit 19 or the block error rate measured by the BLER measuring unit 20. May be.

1 is an electrical block configuration diagram showing a schematic configuration of an optical disc reproducing apparatus according to an embodiment of the present invention. 6 is a flowchart showing an information reading operation from an optical disc including an equalizer boost amount and cut-off frequency setting operation of the optical disc reproducing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk reproduction apparatus 2 Optical disk 11 Control part 12 Spindle motor 13 Seek motor 14 Optical head 15 Equalizer 16 Demodulation process part 17 Error correction process part 18 Decoding process part 19 Jitter value measurement part 20 BLER measurement part 21 Remote control 31 Disc rotation control part 32 Equalizer setting section

Claims (1)

A spindle motor that mounts the optical disk and rotates the optical disk, and reads information from the optical disk by irradiating light to the optical disk rotated by the spindle motor and receiving reflected light from the optical disk. An optical head that outputs a read signal at a voltage level; an equalizer that boosts the read signal output from the optical head and equalizes the waveform of the read signal by cutting off a noise frequency component included in the read signal; Error correction means for detecting an error included in the read signal after the waveform is equalized by the equalizer and correcting the error; and a jitter value of the read signal after the waveform is equalized by the equalizer A jitter value measuring means for measuring, an error rate measuring means for measuring an error detection rate by the error correcting means, Based on the jitter value measured by the jitter value measuring means and the error detection rate measured by the error rate measuring means, the equalizer setting means for variably setting the boost amount and cut-off frequency of the equalizer, and the optical disc of the optical disk by the spindle motor And a disk rotation control means for controlling the rotation so as to be a CLV rotation in which the rotation linear velocity at the information reading position by the optical head of the optical disk is constant or a CAV rotation in which the rotation angular velocity of the optical disk is constant. In an optical disk playback device,
The equalizer setting means includes
The equalizer boost amount is changed to several values, the jitter value is measured by the jitter value measuring means, the error detection rate is measured by the error rate measuring means, and the measured jitter value and error detection rate are calculated. A boost amount setting means for setting the boost amount of the equalizer to an optimal value based on;
The cutoff frequency of the equalizer is changed to several values, the jitter value is measured by the jitter value measuring unit, and the error detection rate is measured by the error rate measuring unit, and the measured jitter value and error detection rate are measured. And a cutoff frequency setting means for setting the cutoff frequency of the equalizer to an optimum value based on
During the reading operation of information from the optical disk by the optical head, every time information for a predetermined address is read,
When the rotation of the optical disk by the disk rotation control means is CLV rotation, the boost amount is set by the boost amount setting means, and when the rotation of the optical disk by the disk rotation control means is CAV rotation, the boost amount setting means In addition to setting of the boost amount by the above-mentioned, an optical disk reproducing apparatus, wherein the cutoff frequency is set by the cutoff frequency setting means.

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