JP2007200502A - Optical disk reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent, in an optical disk reproducing device adopting a shockproof system, noise incorporation in operation for moving an optical pickup backward when a memory area becomes full resulting from high-speed writing for data and the writing is interrupted, and to extend life of move mechanism of the optical pickup. <P>SOLUTION: The device is equipped with a data write-in means E1 for writing the data read by an optical pickup 3 into a memory 10; a memory full determination means E2; a write-in halt means E3 for halting the data writing in the memory when the memory is full; a calculation means E4 for calculating an amount of moving backward of the optical pickup when the write-in is halted; an optical pickup moving backward means E5 for moving the optical pickup by the amount of moving backward; an amount of memory used determination means E6 for determining if the amount of the memory used is below a criterion value for determining resumption of the write-in; a write-in resumption means E7 for resuming operation of the data write-in means at submarginal determination. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disk reproducing apparatus, and more particularly to a technique for reproducing data recorded on an optical disk such as a CD (Compact Disc) and a DVD (Digital Video Disc or Digital Versatile Disc). In particular, data compressed by an audio compression standard such as MP3 (MPegaudio layer 3) is a suitable target.

  In recent years, in addition to the reproduction of digital audio data recorded as CD-DA (Compact Disc-Digital Audio), devices for storing and reproducing compressed audio data on an optical disk such as a CD and a DVD have begun to spread. Hereinafter, a conventional optical disc reproduction technique will be described.

  FIG. 8 is a block diagram showing a general configuration of the optical disk reproducing apparatus. In order to read information such as audio data from the optical disk 1, a laser is irradiated onto the optical disk 1. The laser light reflected by the optical disk 1 reaches the optical pickup (optical head) 3 through the lens 2. The optical pickup 3 converts the reflected light of the laser into an electric signal and outputs it to the head amplifier 4. The head amplifier 4 amplifies the electric signal to generate an error signal (RF signal, focus error signal and tracking error signal) and outputs the error signal to the servo LSI 5. The servo LSI 5 performs focus servo processing based on the input focus error signal, amplifies the control signal via the driver 7, and controls the operation of the lens 2 and the optical pickup 3. Further, the servo LSI 5 performs tracking servo processing and traverse servo processing based on the tracking error signal, amplifies the control signal via the driver 7, controls the operation of the optical pickup 3, and performs tracking control. Finally, a synchronization signal is generated from the error signal (RF signal, focus error signal, and tracking error signal) obtained from the head amplifier 4, and CLV (Constant Linear Velocity) servo processing is performed based on the synchronization signal. And the number of revolutions of the spindle motor 8 is controlled via the driver 7. The microcontroller 13 is responsible for overall control.

  On the other hand, the RF signal obtained from the head amplifier 4 is demodulated into a binarized signal in the signal processing circuit 6. Then, a DF-DAC (Digital Filter-Digital Analog Converter) circuit 11 DA converts the binarized signal, and the converted analog signal becomes an analog audio signal. The audio output unit 9 outputs this analog audio signal.

  Here, by providing the memory 10, it is possible to prevent sound interruption caused by vibration of the optical disc apparatus itself during reproduction of audio data. The prevention of sound interruption will be described. The DF-DAC circuit 11 DA converts the signal binarized in the signal processing circuit 6. The binarized signal is temporarily stored in the memory 10. Next, the DF-DAC circuit 11 reads the signal temporarily stored in the memory 10 and performs DA conversion, and outputs the obtained analog audio signal from the audio output unit 9. By utilizing the memory 10 in this way, even if a situation in which information cannot be read from the optical disk 1 due to vibration or the like occurs unexpectedly, the information stored in the memory 10 is read and output in advance. Sound interruption can be prevented. This mechanism is called a shock proof system.

  There are various standards of optical disks. Hereinafter, CD-DA discs and CD-ROM discs will be cited as examples of standards, and their characteristics will be described.

  When the optical disc 1 is a CD-DA disc, one sample of 2 bytes is recorded alternately on the left and right as shown in FIG. The audio data is composed of 2352 bytes per frame. The memory 10 stores only audio data. The DF-DAC circuit 11 performs DA conversion of the audio data stored in the memory 10. The audio output unit 9 outputs the converted analog audio signal.

  When the optical disc 1 is a CD-ROM disc, data is recorded as shown in FIG. The CD-ROM disc shown in FIG. 7 has a SYNC (synchronization) portion and a header portion, and further has a powerful error correction function based on ECC (error correction code). The memory 10 stores compressed audio data. The decoder 12 decodes (decompresses) the compressed audio data, and the DF-DAC circuit 11 performs DA conversion on the decoded data. The audio output unit 9 outputs an analog audio signal after DA conversion.

  In the shock proof system, data is read from the optical disk 1 at high speed and written into the memory 10. As a result, the memory area becomes full and there is no free space for data writing, and writing may have to be interrupted. In this case, if it is left in a state where data writing is interrupted, the optical pickup 3 will flow more and more toward the outer periphery.

  As a countermeasure, there is a method of stopping the rotation of the optical disc 1. In this case, when the audio data stored in the memory 10 is consumed and an empty area is generated again in the memory 10, the rotation of the optical disc 1 is restarted. However, it takes time to write data again. When the capacity of the memory 10 is small, sound interruption may occur.

  There is also a method for preventing the interruption of writing by adjusting the rotation speed of the optical disc 1. This method of adjusting the rotation speed is difficult to use when reproducing compressed audio data recorded on a CD-ROM. This is because the compressed audio data is compressed unlike the data recorded as CD-DA, so that the speed at which the data stored in the memory 10 is consumed is low.

Therefore, Patent Document 1 proposes a method of repeating the operation of returning the optical pickup 3 flowing toward the outer periphery to the writing interrupted position.
JP-A-5-325506 (page 3-5, FIG. 1-7)

  However, when the operation of returning the optical pickup to the writing interruption position is repeated, there may be a side effect that the operation sound when moving the optical pickup is mixed with the analog audio signal and output as noise. Further, since the optical pickup is repeatedly moved, the life of the optical pickup moving mechanism may be shortened.

  The present invention has been created in view of such circumstances, and in the operation of moving the optical pickup back when the memory area is full due to high-speed data writing and the writing is temporarily interrupted, noise is mixed. In addition, the object is to extend the life of the moving mechanism of the optical pickup.

An optical disk reproducing apparatus according to the present invention
Data writing means for writing data read from the optical disc through the optical pickup into the memory;
Memory full determination means for determining the memory full by monitoring the write state of the memory;
Write stop means for temporarily stopping data writing to the memory by the data writing means when the memory full determination means determines that the memory is full;
A return movement amount calculating means for calculating a return movement amount of the optical pickup when the writing stop means becomes active;
An optical pickup return movement means for moving the optical pickup back by the return movement amount calculated by the return movement amount calculation means;
Memory usage determining means for determining whether or not the memory usage has fallen below a predetermined write restart determination reference value for resuming data writing to the memory;
And a write restarting means for restarting the operation of the data writing means when the memory usage amount determining means makes a lower determination.

  In this configuration, when the memory full determining unit determines that the memory is full due to high-speed data writing, the write stopping unit temporarily stops data writing to the memory. Then, the return movement amount calculation means calculates an optimum return movement amount for the optical pickup, and the optical pickup return movement means moves the optical pickup back by the optimum return movement amount. Even when data writing is stopped, data is read from the memory, and the memory usage is reduced. The memory usage is monitored by the memory usage determining means. When the memory usage is less than the write resumption determination reference value, the write resuming means restarts the data writing means and resumes data writing to the memory. In this case, the return movement of the optical pickup is only one time based on the optimal return movement amount, and is not a repeated movement as in the case of the prior art. It is possible to extend the life of the moving mechanism.

In the above configuration, the return movement amount calculation means calculates the return movement amount D based on the data write interruption time Ts, the optical pickup return movement required time Tm, and the movement speed V of the optical pickup.
D = (Ts−Tm) × V ……………………………… (1)
There is a mode of calculating by.

Also, the return movement amount calculating means, the data write interrupt time Ts, and memory capacity ΔQ consumed until data writing resumes, based on the bit rate R _B data,
Ts = ΔQ / R _B ……………………………………… (2)
There is a mode of calculating by.

Summary,
D = {(ΔQ / R _B ) −Tm} × V (3)
It becomes.

  In the above configuration, the optical pickup return movement unit may stop the return movement of the optical pickup when the optical pickup return movement required time Tm is longer than the data write interruption time Ts.

  Further, in the above configuration, the optical pickup return moving means sets the optical pickup return movement destination to the innermost position when the return movement destination of the optical pickup is on the inner peripheral side with respect to the lead-in of the innermost peripheral session. There is a mode of setting the lead-in around the circumference.

  In the above configuration, when the optical pickup reaches the outermost session lead-out during the operation of the memory usage determining means, the optical pickup is kept in the outermost session lead-out. There is an aspect of being configured.

  According to the present invention, the return movement of the optical pickup is only once based on the optimal return movement amount, and the return movement of the optical pickup is not repeated, so that it is possible to prevent noise from being mixed into the reproduction signal. In addition, since the optical pickup is not returned and moved repeatedly, the life of the optical pickup moving mechanism can be extended.

  Embodiments of an optical disk reproducing apparatus according to the present invention will be described below in detail with reference to the drawings. As the configuration of the optical disc playback apparatus, the same general configuration as the conventional one can be used, so that description will be given with reference to FIG.

  FIG. 1 is a block diagram showing a configuration of an optical disk reproducing apparatus according to an embodiment of the present invention. In FIG. 1, E1 is a data writing means for writing data read from the optical disc 1 through the optical pickup 3 into the memory 10, E2 is a memory full determining means for monitoring the writing state of the memory 10 and determining memory full, and E3 is Write stop means for stopping data writing to the memory 10 by the data write means E1 when the memory full determination means E2 determines that the memory is full, E4 is the return of the optical pickup 3 when the write stop means E3 becomes active Return movement amount calculation means for calculating the movement amount D, E5 is an optical pickup return movement means for moving the optical pickup 3 back only once by the return movement amount D calculated by the return movement amount calculation means E4, and E6 is for the memory 10. To resume data writing, the memory usage Q is determined to be Memory usage determination means for determining whether or not lower than the reference value Qth, E7 is a write resuming means for resuming the operation of the data writing means E1 when the determined memory usage determination unit E6 is below.

  Next, the operation of the optical disk reproducing apparatus of the present embodiment configured as described above will be described with reference to the flowchart of FIG.

  First, in step S1, the data writing means E1 starts writing the audio data recorded on the optical disc 1 read by the optical pickup 3 into the memory 10.

  Next, in step S2, the memory full determination means E2 checks whether or not data writing to the memory 10 is memory full. If the memory is not full and there is free space, data writing is continued. If there is no free space and the memory is full, the process proceeds to step S3.

  In step S3, the write stop unit E3 stops data writing by the data write unit E1.

  Next, in step S4, the return movement amount calculation means E4 calculates a return movement amount D that is an amount of how much the optical pickup 3 is moved to the inner peripheral side. A method for calculating the optimum return movement amount D will be described later.

  Next, in step S5, the optical pickup return moving means E5 moves the optical pickup 3 to the inner peripheral side by the optimum return movement amount D. This return movement is limited to once after data writing is stopped.

  In step S6, the memory usage determining means E6 checks the current memory usage Q of the memory 10 while data writing is stopped, and resumes writing, which is the memory capacity when resuming data writing is permitted. It is confirmed whether or not the judgment reference value Qth is below. When the current memory usage Q falls below the write resumption determination reference value Qth, the process returns to step S1 and the write resuming means E7 restarts the data writing means E1 to resume data writing to the memory 10.

FIG. 3 shows the transition of the data write state in the memory 10. In FIG. 3A, the memory is full. The amount of decrease from the memory full capacity Q _F to the write restart determination reference value Qth is the memory capacity ΔQ that should be consumed before the data write is restarted.

  Even during a period in which data writing is stopped, data reading is performed for continuous reproduction of audio data, and the memory usage Q gradually decreases. When the current memory usage Q decreases from FIG. 3 (b) to FIG. 3 (c) and falls below the write restart determination reference value Qth, the determination in step S6 in FIG. Is done.

  FIG. 4 illustrates a method of calculating the return movement amount D. FIG. 4A shows a state where the optical pickup 3 is moved back from the writing interruption position. FIG. 4B shows a state in which the optical pickup 3 moves from the return position toward the outer peripheral side at a predetermined moving speed V.

In the case of CD, the unit is a frame. The return movement amount D (frame) of the optical pickup 3 is Ts (seconds) for the interruption time until resumption of writing, Tm (seconds) for the return movement time of the optical pickup, and V (frame / second) for the movement speed of the optical pickup 3 As
D = (Ts−Tm) × V ……………………………… (1)
It becomes.

  The data write interruption time Ts includes the optical pickup return movement required time Tm. This data write interruption time Ts is equal to the time from when the optical pickup 3 returns from the write interruption position to the return position, and further reverses and returns to the write interruption position. It takes time (Ts−Tm) for the optical pickup 3 to return from the return position to the write interruption position. Finally, the distance is D. The optical pickup 3 moves at the moving speed V over the distance D, that is, the return movement amount D. Therefore, the above formula is established.

The data write interruption time Ts can be obtained on the basis of the memory capacity ΔQ (bits) consumed until the data writing is resumed in FIG. 3 and the bit rate R _B (bits / second) of the audio data.

Ts = ΔQ / R _B ……………………………………… (2)
In the case of audio data recorded as CD-DA, the bit rate of audio data is a standard for reproducing 75 frames of audio per second. Since one frame is 2352 bytes, R _B = 75 × 2352 × 8 = 14111200 (bits / second).

  In the case of compressed audio, bit rate information is described in various headers, so that it may be used. For example, as shown in FIG. 5, in the case of MP3, there is a frame header for each frame, and the bit rate is described therein. In compressed audio, there is also a variable bit rate stream having a different bit rate for each frame. In the case of the variable bit rate, it is possible to obtain a more accurate data write interruption time Ts by calculating the average bit rate of the audio data already written in the memory 10 and using that value. For example, in the case of MP3, the average bit rate can be calculated by obtaining the bit rate of each frame from the frame header of FIG. 5 and dividing the sum of the bit rates by the number of frames.

Finally, when formula (1) and formula (2) are put together,
D = {(ΔQ / R _B ) −Tm} × V (3)
It becomes.

For example, the memory capacity ΔQ consumed until the data writing restarts 819200 (bits), the bit rate R _B of the audio data 128000 (bits / sec), the optical pickup return travel time Tm 0.2 seconds, an optical pickup 3 If the moving speed V is 75 (frames / second),
D = {(819200/128000) −0.2} × 75
= 465 (frame)
It becomes.

The greater the bit rate R _B in the formula (3), the movement amount D returns the optical pickup 3 is reduced. In other words, audio data recorded as a CD-DA disc and compressed audio data such as MP3 having a high bit rate has a high rate of consuming data written in the memory 10. For this reason, the return movement amount D of the optical pickup 3 toward the inner periphery may be set small. On the other hand, for compressed audio data having a low bit rate, the speed at which the data written in the memory 10 is consumed is slow, so the return movement amount D of the optical pickup 3 is set large.

  The moving speed V of the optical pickup 3 is determined by the rotational speed of the optical disc 1. In the case of CD, 75 (frame / second) at 1 × speed and 150 (frame / second) at 2 × speed.

  Note that V is a speed at which the optical pickup 3 moves from the inner circumference side toward the outer circumference side during normal operation, and is not necessarily the speed at which the optical pickup 3 is moved back.

  By the way, if the optical pickup return movement required time Tm becomes longer than the data writing interruption time Ts, it means that the time required for the return movement is longer. In such a case, the process of moving the optical pickup 3 back to the inner peripheral side is not performed.

  Furthermore, when the optical pickup 3 is moved from the position where the writing is interrupted by the return movement amount D of the optical pickup 3, the destination is inside the lead-in area of the innermost session. Is set to the innermost lead-in area. By doing so, it is possible to avoid excessive movement to the inner peripheral side.

  In addition, during reproduction near the outer periphery of the optical disc 1, it is also conceivable that the optical pickup 3 reaches the lead-out area of the outermost peripheral session while data writing is interrupted due to a calculation error or the like. In such a case, by keeping the optical pickup 3 in the lead-out area of the outermost peripheral session, the optical pickup 3 can be prevented from flowing beyond the lead-out area.

  In the above description, the moving direction of the optical pickup 3 during normal operation is the direction from the inner peripheral side to the outer peripheral side. However, the direction is not limited to this and may be the opposite direction. In that case, the direction of the return movement is a direction from the inner peripheral side toward the outer peripheral side.

  The optical disk playback apparatus of the present invention is particularly useful for playback of audio data recorded as CD-DA and audio data compressed by an audio compression standard such as MP3 recorded on an optical disk such as a CD or DVD. Further, it can be applied not only to audio data but also to reproduction of video data and the like.

The block diagram which shows the structure of the optical disk reproducing | regenerating apparatus in embodiment of this invention The flowchart which shows operation | movement of the optical disk reproducing device in embodiment of this invention. The figure showing the breakdown of the memory capacity in the embodiment of the present invention The figure showing the return movement amount of the optical pickup in the embodiment of the present invention and the movement after resuming writing Diagram showing the frame header of MP3 Diagram showing CD-DA format Diagram showing CD-ROM format FIG. 2 is a block diagram showing a configuration of a general optical disc playback apparatus, which is applied to an embodiment of the present invention.

Explanation of symbols

E1 Data writing means E2 Memory full judgment means E3 Write stop means E4 Return movement amount calculation means E5 Optical pickup return movement means E6 Memory usage amount judgment means E7 Write resumption means 1 Optical disk 2 Lens 3 Optical pickup 4 Head amplifier 5 Servo & signal processing LSI
6 Signal Processing Circuit 7 Driver 8 Spindle Motor 9 Audio Output Unit 10 Memory 11 DF-DAC Circuit 12 Decoder 13 Microcontroller

Claims (6)

Data writing means for writing data read from the optical disc through the optical pickup into the memory;
Memory full determination means for determining the memory full by monitoring the write state of the memory;
Write stop means for temporarily stopping data writing to the memory by the data writing means when the memory full determination means determines that the memory is full;
A return movement amount calculating means for calculating a return movement amount of the optical pickup when the writing stop means becomes active;
An optical pickup return moving means for moving the optical pickup back by the return movement amount calculated by the return movement amount calculating means;
A memory usage determining means for determining whether or not the memory usage is below a predetermined write restart determination reference value for resuming the writing of data to the memory;
An optical disk reproducing apparatus comprising: a writing restarting unit that restarts the operation of the data writing unit when the memory usage amount determining unit makes a determination that the memory usage is below. The return movement amount calculating means calculates the return movement amount D based on the data write interruption time Ts, the optical pickup return movement required time Tm, and the movement speed V of the optical pickup.
D = (Ts−Tm) × V
The optical disk reproducing apparatus according to claim 1, which is calculated by: The return movement amount calculating means, the data write interrupt time Ts, and memory capacity ΔQ consumed until data writing resumes, based on the bit rate R _B data,
Ts = ΔQ / R _B
The optical disk reproducing apparatus according to claim 2, which is calculated by:   3. The optical disk reproducing apparatus according to claim 2, wherein the optical pickup return movement means stops the return movement of the optical pickup when the optical pickup return movement required time Tm is longer than the data write interruption time Ts.   The optical pickup return movement means sets the return movement destination of the optical pickup to the innermost lead-in when the return movement destination of the optical pickup is on the inner peripheral side than the lead-in of the innermost peripheral session. The optical disk reproducing device according to claim 1.   The optical pickup is configured to keep the outermost session lead-out when the optical pickup reaches the outermost session lead-out during the operation of the memory usage determining means. An optical disk reproducing apparatus according to any one of claims 1 to 5.

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