1. Field of the Invention
The present invention relates to a data reproducing apparatus for reproducing data recorded on a recording medium such as a storage disc and to a program for performing a data reproducing process.
2. Description of the Related Art
On a recording medium such as a compact disc (CD), data including music data is recorded on a pit series formed along concentric tracks provided thereon. In a data reproducing apparatus for reproducing data recorded on CD, an installed CD is driven by a spindle motor, a light beam such as a laser beam is emitted to the tracks on CD, and changes in a reflected light caused by the pits formed in the tracks are detected by a pickup to reproduce data. The pickup operates under a tracking control and a focusing control to reproduce data. Since the pickup does not contact with a recording surface of CD to reproduce data, the data reproducing apparatus has an advantage that the recording surface of CD receives no damage during the reproducing operation. When there is an error in the reproduced data, such error may be corrected by a digital signal processing. On the contrary, the data reproducing apparatus has a disadvantage that in case that unexpected force is applied to the pickup due to an external vibration, shock, or other cause, the so-called “sound-skipping phenomenon” happens and such sound skipping cannot be corrected by an error correction in the digital signal process.
To solve the above disadvantage, the so-called shockproof reproducing function is widely used in data reproducing apparatuses. The shockproof reproducing function employs a memory control method, in which the pickup reads out data from CD and writes the same data into a memory at a rate higher than a rate at which the data is reproduced, and as a result the data is written into the memory within a time period of one several-th of a time period in which the data is read out. In the memory control method, if unexpected force is applied to the pickup due to a vibration, shock, or other cause, and a tracking control and a focusing control are disturbed, resulting in errors in the read out data which can not be corrected, the data may be read out and written in the memory again during the time difference between the time period of reading out data and that of writing data. There have been proposed many data reproducing apparatuses using such memory control method. Typical structure of the conventional data reproducing apparatuses will be described hereafter.
In a disc player disclosed in Japanese laid-open patent application No. 7-14309, an earthquake resistant memory controller and DRAM compose the shockproof reproducing function. Either a shockproof reproducing mode or a normal reproducing mode is automatically selected depending on how many times the sound skipping happens during a certain period of time. In the present arrangement, even if the sound skipping should happen often due to external vibration, continuity of the reproduced signal may be secured without troubling the user with manually selecting the mode. If such shockproof reproducing function is employed in CD player for automobile or in a portable CD player, useless power consumption is reduced, extending a life time of a battery.
Further, in a display device of CD reproducing apparatus with the shockproof function disclosed in Japanese laid-open patent application No. 8-203254, audio data of CD is previously stored in a memory at a speed which is two times higher than the normal reproducing speed for a predetermined period of time through a pickup, a signal processing circuit and a shockproof circuit, and the audio data stored in the memory is output to a speaker at a normal reproducing speed with audio-data reading operation of the pickup remaining in a pause state. Even when sound skipping should happen, outputting operation of the audio data stored in the memory keeps outputting the audio data, and operation for restarting data-reading operation of the pickup is repeatedly performed before all the stored audio data has been output to secure continuity of the reproducing signal. In an optical disc reproducing apparatus of Japanese laid-open patent application No. 8-335364, an optical disc is driven at a rotational speed higher than the normal rotational speed to store audio data in a first memory. When a “track jump” or “out of focus” is detected, an instruction is immediately issued, and thereby a previous track is re-accessed, which track was accessed before the audio signal is disconnected, and input operation for inputting the audio signal at a high speed ceases and no data is supplied to the first memory to be stored therein. Meanwhile, the reproducing apparatus is controlled so as to keep outputting the audio signal from the first memory at the normal speed, and thereby a music signal is not disconnected, and the reproducing apparatus re-starts the reproducing operation before all the data stored in the memory has been outputted, preventing sound skipping due to an external vibration. Japanese laid-open patent application No. 10-112124 discloses a disc reproducing apparatus that reproduces music by reading out music data from a storing means in which music data read out from a disc type recording medium is temporarily stored. The music data is written into recording means at a rate higher than a rate at which music is reproduced, until music data that is stored therein and is not read out reaches a certain amount. After the music data that has been stored in the recording means and has not been read out reaches a certain amount, the music data is written into the recording means at a rate substantially same as the rate at which music is reproduced, which prevents generation of a disconnected sound and sound skipping, thereby enhancing shock-proof for continuous vibration, and preventing generation of a disconnected sound and sound skipping. Japanese laid-open patent application Nos. 2000-195174 and 2000-195175 disclose optical disc reproducing apparatuses that read out compressed music data at a high rate from a writable MD driven at a high rotational speed and write the same data onto DRAM, and read out the compressed music data from DRAM at a low rate. When DRAM becomes full of music data, writing operation ceases and an alarm signal notifying that DRAM has become full of data is given, and when the amount of data has decreased to an amount less than a standard amount, an alarm signal is generated to notify that there is left an empty space in DRAM. When the alarm signal notifying that DRAM has become full of data is given, the standard amount is increased or decreased depending on whether or not data is being read out from the proximity of end of an interval where data is continuously recorded, thereby preventing generation of sound skipping and reducing useless power consumption.
A disc reproducing apparatus disclosed in Japanese laid-open patent application No. 2002-15521 reproduces a signal recorded on a disc at a rate higher than the normal rate and records the signal on a memory. When shockproof is effective and outputs a signal reproduced from the memory signal even if an external shock is applied while the signal is reproduced from the memory, a low frequency emphasis is prohibited and a frequency characteristic is kept flat, thereby reducing chances of generation of sound skipping even when a strong vibration is applied due to a sound pressure produced by an built-in speaker. Further, an optical disc reproducing apparatus disclosed in Japanese laid-open patent application Nos. 2002-150666 and 2002-245721 previously reads out audio data from CD and stores the same in a memory for a shockproof function which prevents generation of sound skipping due to unexpected shock and vibration applied thereto. The reproducing apparatus performs communicating operation corresponding to sub code Q data of audio data, a tune number, and time.
In the conventional apparatuses described above, noting is described about in what state the pickup works to reproduce data. When the pickup reads data recorded on CD, CPU or the like generates a reproduction start instruction to make the pickup move in the radius direction of CD. But when the pickup starts reproducing operation from its stop or pause state, or from its fast forward reproducing, repeat-reproducing or fast rewind state, or when the pickup is in the steady state for performing reproducing operation, the pickup moves in different ways. In the transient state from its pause state or from its fast forward reproducing state to its normal reproducing state, the pickup receives heavy acceleration force or deacceleration force, but in the steady state in which the pickup performs the reproducing operation, the pickup does not receive acceleration or deacceleration force. That is, in the transient state from its pause state or from its fast forward reproducing state to its normal reproducing state, the tracking control or focusing control is easily disturbed, and therefore sound skipping is often generated.
Further, when the pickup receives an external shock or vibration in the transient state, a possibility of generation of sound skipping increases greatly due to a multiplier effect of the heavy acceleration or deacceleration force and the shock or vibration. For example, in an electronic instrument apparatus to which CD including music data can be installed, a keyboard of the apparatus is often played while CD is reproduced. When a user starts playing the keyboard at the same time as CD reproducing operation starts, the multiplier effect of the heavy acceleration or deacceleration force applied to the pickup and the shock or vibration greatly increases the possibility of generation of sound skipping.
Meanwhile, another disc reproducing apparatus has been proposed, for instance, in Japanese laid-open patent application No. 11-176080. In the disc reproducing apparatus, it is analyzed in detail how sound skipping happens to provide useful information for solving such disadvantage. It is pointed out in the above specification that sound skipping can be caused even in the apparatus with the shockproof function, and that such sound skipping can be caused by a defect of the optical pickup itself, a shift in setting position of the optical pickup, a physical factor of a circumstance in which the reproducing apparatus is used, and a defective signal processing for connecting sounds. To study in detail how sound skipping happens, a detecting process such as a process for comparing levels is executed based on variables and constants to be processed by a micro-computer for processing a signal, including an amount of data stored in a memory, and the resultants thereof are displayed. When sound skipping happens, it is judged whether such sound skipping is caused by a physical factor such as a defective recording medium or by a defective signal processing for connecting sounds.
The arrangement described above can determine what is the cause for the sound skipping, but nothing is described or suggested about a counter measure for preventing or suppressing generation of sound skipping.
An object of the invention is to provide a data reproducing apparatus and a data processing program, which can suppress generation of sound skipping even if a pickup for reading out data recorded on a recording medium such as CD is in a transient state from its stop or pause state or from its fast moving state to its normal data reproducing state. According to one aspect of the present invention, there is provided command generating means for generating a control command for controlling data-reading operation.
And a writing address is incremented from a starting address every time when data is written into a predetermined memory, and a reproducing address is incremented from a starting address every time when data is read out from the memory, thereby setting a predetermined addresses.
Further, the data read out by the data-reading means is written to the writing address in the memory in accordance with a generated control command of requesting to start data-reproducing operation, and operation for reading out data from the memory is suspended until the writing address reaches the predetermined address, and operation starts for reading out data from the reproducing address in the memory when the writing address reaches the predetermined address.
With the above arrangement, the present invention has an advantage that the pickup for reading data recorded on a recording medium such as CD can prevent generation of sound skipping even in its transient state from its stop or pause state or from its fast moving state to its data reproducing state.
Now, a data reproducing apparatus according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
A shock memory 14 and a memory controller 15 provide a shock-proof reproducing function. More particularly, the memory controller 15 writes the music data read out from CD 11 and processed by CD-DSP 13 onto the shock memory 14 at a rate which is twice a reproducing rate, and reads out and outputs to CD-DSP 13 at the reproducing rate. In CD-DSP 13, DAC circuit converts the music data input from the memory controller 15 into an analog signal to output a CD reproduced audio signal. CPU 16 controls CD-DSP 13 and the memory controller 15, and detects whether a CD cover switch 17 has been turned on or not. CPU 16 communicates with the electronic instrument system 18 to exchange a command and data. Thought not shown, CPU 16 is an one-chip LSI which comprises ROM on which a program for reproducing and processing data, a communication program for communicating with the electronic instrument system 18, and initial data used at initialization are stored, and RAM having registers and flags.
The sound source section 28 reads out a digital waveform data from a waveform ROM 30 and inputs the same to DAC 31 under sound-control of CPU 21. DAC 31 converts the digital waveform data to an audio signal and inputs the same to a mixer 32. The mixer 332 combines the audio signal from DAC 31 and the CD reproduced audio signal input from the CD-DSP 13 of
Now, operation of the data reproducing apparatus used in the embodiment will be described. Structure of addresses and data in the shock memory 14 will be described with reference to
In general, since an increment rate of the writing address “WA”, i.e., a writing rate is set to a rate which is twice an increment rate of the reproducing address “PA”, i.e., a reproduction rate, the writing address “WA” precedes the reproducing address “PA”. Therefore, data between the writing address “WA” and the reproducing address “PA” is available data which has not been reproduced. But the reproducing address “PA” stays at the starting address and remains in a reproduction waiting state before the writing address WA reaches the accumulation judging address “JA”. After the writing address WA reaches the accumulation judging address “JA”, reading data from the shock memory 14 starts and the reproducing address “PA” is incremented. Therefore, in the data state shown in
In a sound-generation starting state shown in
In a reproducing state shown in
In the reproducing state shown in
Now, a data reproducing process to be performed by CPU 16 and the memory controller 15 will be described with reference to
When it is determined at step SA2 that CD has been installed, an initializing process is executed at step SA4. Then, a setting process, CD control process, a memory control process, and other processes are executed respectively at steps SA5, SA6, SA7, and SA8. In the CD control process, CD is driven, and a reproducing process, a stop process, a fast forward process, a fast rewind process and a pause process are executed in response to manipulation of the switches shown in
When it is determined at step SC2 that the stop flag STOPF is set to “0”, it is judged at step SC7 whether or not the reproducing flag PLAYF is set to “1”. When it is determined at step SC7 that the reproducing flag PLAYF is set to “1”, since the reproduction/pause switch is turned on in the reproducing state, CPU 16 transits from the reproducing state to the pause state, and sets the pause flag PAUSEF to “1” at step SC8 and resets the reproducing flag PLAYF to “0” at step SC9. Then the operation returns to the main routine process. When it is determined at step SC7 that the reproducing flag PLAYF is set to “0”, since the reproduction/pause switch is turned on in the pause state, CPU 16 transits from the pause state to the reproducing state and resets the pause flag PAUSEF to “0” at step SC10 and sets the reproducing flag PLAYF to “1” at step SC11. Then the operation returns to the main routine process.
When it is determined at step SC1 that the reproduction/pause switch is not turned on, it is judged at step SC12 whether or not the stop switch is turned on. When the stop switch is turned on, it is judged at step SC13 whether the stop flag STOPF is set to “1” or not. When the stop flag STOPF is set to “1”, since CPU 16 has been brought in the stop state, on-manipulation of the stop switch gives no effect and the operation immediately returns to the main routine process. When the stop flag STOPF is set to “0”, since CPU 16 is in the reproducing state or in the pause state, the stop flag STOPF is set to “1” at step SC14 and it is judged at step SC15 whether the reproduction flag PLAYF is set to “1” or not. When the reproduction flag PLAYF is set to “1”, the reproduction flag PLAYF is reset to “0” at step SC16. When the reproduction flag PLAYF is set to “0”, it is judged at step SC17 whether the pause flag PAUSEF is set to “1” or not. When the pause flag PAUSEF is set to “1”, the pause flag PAUSEF is reset to “0” at step SC18. After the pause flag PAUSEF has been reset to “0”, or after the pause flag PAUSEF has been reset to “0”, the writing address “WA” is set to the same starting address as the reproducing address “PA” at step SC4, and the accumulation judging address “JA” is set by adding a certain address difference CA to the writing address “WA” at step SC5. The register COUNT is reset to “0” at step SC6 and the operation returns to the main routine process.
When it is determined at step SC12 that the stop switch is not turned on, it is judged at SC19 (
When it is determined at step SC21 (
When it is determined at step SC25 that the fast-rewind switch is not turned off, it is judged at step SC27 whether the repeat switch is turned on or not. When the repeat switch is turned on, it is judged at step SC28 whether a repeat flag REPEATF is set to “1” (Repeat setting) or not. When the repeat flag REPEATF is set to “0”, it is judged at step SC29 whether a repeat starting-point flag BEGINF is set to “0”. When the repeat starting-point flag BEGINF is set to “0”, the reproducing address “PA” is stored in a register APOINT to set a starting address of a repeat reproduction at step SC30. Then, the repeat starting-point flag BEGINF is set to “1”, and LED 8 is made to flash at step SC31. The operation returns to the main routine process. When it is determined at step SC29 that the starting-point flag BEGINF is set to “1”, the reproducing address “PA” is stored in a register BPOINT to set a terminal address of the repeat reproduction at step SC32. Then, the repeat starting-point flag BEGINF is reset to “0” at step SC33, and the repeat flag REPEATF is set to “1” at step SC34 to make LED 8 flash. The operation returns to the main routine process.
When it is determined at step SC28 that the repeat flag REPEATF is set to “1”, a time counting operation starts at step SC35. It is judged at step SC36 whether the repeat switch is turned off or not. When the repeat switch is not turned off, the operation returns to the main routine process. When the repeat switch is turned off, it is judged at step SC37 whether a certain time has lapsed or not. When a certain time has not lapsed, the operation returns to the main routine operation. When a certain time has lapsed, that is, when the repeat switch has been kept on for more than a certain time, the repeat flag REPEATF is reset to “0” and LED 8 is turned off at step SC38. The repeat reproduction is terminated and the operation returns to the main routine process.
Meanwhile, when the pause flag PAUSEF is set to “0”, since CPU 16 is in the reproduction waiting state, it is judged at step SD4 whether the writing address “WA” has reached the accumulation judging address “JA” or not. In other words, it is judged whether or not data read out from CD by the pickup 12 is processed in the CD-DSP13 and written into the shock memory 14 by the memory controller 15, and further judged whether or not the writing address “WA” is incremented (
When it is determined at step SD2 that the reproduction flag PLATF is set to “1”, CPU 16 is in the normal reproducing state or the pickup 12 is moving fast in a fast reproducing or fast rewinding state. Therefore, it is judged at step SD9 whether the fast forward flag FFWF is set to “0”. When the fast forward flag FFWF is set to “0” and CPU 16 is not in the fast reproducing state, it is judged at step SD10 whether the fast-rewind flag FRWF is set to “0” or not. When the fast-rewind flag FRWF is set to “0”, CPU 16 in the normal reproducing state. In this case, it is judged at step SD11 whether or not the reproducing address “PA” is at the same address as the writing address “WA”.
When the reproduction flag PLAYF is set to “1” and when the reproducing address “PA” is at the same address as the writing address “WA”, there can be two states. In one state, the writing address “WA” has caught up the reproducing address “PA”, as shown in
Therefore, when the reproducing address “PA” is at the same address as the writing address “WA”, it is necessary to judge whether or not the writing address “WA” catches up the reproducing address “PA” and the shock memory 14 is full of available data, or it is necessary to judge whether or not the reproducing address “PA” catches up the writing address “WA” and there is no available data in the shock memory 14. For that purpose, it is judged at step SD12 whether or not the register COUNT for counting available data in the shock memory 14 is set to “0”. When the register COUNT is set to “0”, since there is left no available data in the shock memory 14, data input from CD-DSP 13 is written into the shock memory 14 at the writing address “WA” at step SD13. Then the writing address “WA” is incremented at step SD14, and a value of the register COUNT is incremented at step SD15.
After the value of the register COUNT has been incremented, or when it is determined at step SD11 that the reproducing address “PA” is not at the same address as the writing address “WA”, it is judged at step SD16 whether or not the pause flag PAUSEF is set to “0”. When the pause flag PAUSEF is set to “1”, data is not read out from the shock memory 14, and the operation returns to the main routine process. Meanwhile, when the pause flag PAUSEF is set to “0”, data at the reproducing address “PA” of the shock memory 14 is read out, and output to CD-DSP 13 at step SD17 to make the electronic instrument system generate a sound. Then the reproducing address “PA” is incremented at step SD18, and a value of the register COUNT is decremented at step SD19. The operation returns to the main routine process.
When it is determined at step SD12 that the register COUNT is not set to “0”, or when the writing address “WA” has caught up the reproducing address “PA” and the shock memory 14 is full of available data, operation for writing data into the shock memory 14 is interrupted and only operation for reading data from the shock memory 14 is executed. In other words, data is read out from the reproducing address “PA” of the shock memory 14 and output to CD-DSP 13 at step SDS17, and then the reproducing address “PA” is incremented at step SD18 and the value of the register COUNT is decremented at step SD19. Then the operation returns to the main routine process. It should be noted that the pickup 12 temporarily stops at a position where it finished reading CD and is brought to a reading waiting state in the CD control process at step SA6 in
As described above, CPU 16 and the memory controller 15 in the embodiment increments the writing address “WA” from the starting address every time data is written in the shock memory 14, and increments the reproducing address “PA” from the starting address every time data is read out from the shock memory 14 and writes data read out by the pickup 12 to the writing address “WA” of the shock memory 14. CPU 16 and the memory controller 15 suspend operation of reading out data from the shock memory 14 until the writing address “WA” reaches the accumulation judging address “PA”, and start operation of reading out data from the reproducing address “PA” of the shock memory 14 when the writing address “WA” has reached the accumulation judging address “PA”. Therefore, generation of a disconnected sound can be prevented during the transient state of the pickup 12 from the stop state, the fast forward state, or the fast rewind state to the reproducing state.
The memory controller 15 uses the shock memory 14 as a ring buffer, and executes an address control operation to circularly increment the writing address “WA” and the reproducing address “PA”, thereby replacing previously written data with another data to be newly written. Therefore, even though vast amount of data is read out form CD 11, there is no need to use a memory having a large memory capacity, which will contribute to reduce cost of the device and to make the device more compact in size and light in weight.
In response to a control command requesting to start data reproduction, the memory controller 15 adds a certain number of addresses “CA” to the start address, that is, the writing address “WA” to set the accumulation judging address “JA”. The address “CA” is equivalent to a number of addresses to be incremented while the pickup 12 transits from the transient state to the normal state. Therefore, since data is read out from the shock memory 14 to generate a sound, which data is read out from CD and stored in the shock memory 14 after a time period has lapsed during which a tracking control operation and a focus control operation are unstable so that a disconnected sound can be caused often, the generation of a disconnected sound is prevented.
In the above mentioned embodiment, the data reproducing apparatus according to the present invention has been described, which is applied to the electronic keyboard instrument of
The data reproducing apparatus according to the present invention is not to be applied only to such an apparatus as reproducing music data recorded on CD, such as the electronic keyboard instrument, the electronic drum instrument, and the portable type CD player. In a data reproducing apparatus for reading out and reproducing data from various discs including DVD, CD-ROM, CD-R, CD-RW and MD, which store content data other than music data, such as image data and text data, since a tracking control operation and a focus control operation are unstable in a transit state of a pickup from its transient state to its steady state, external shock or vibration can often cause abnormalities in reproduced data. Therefore, the data reproducing apparatus according to the present invention can prevent generation of abnormalities in the reproduced data in the data reproducing apparatus with a pickup for reproducing data.
In the above mentioned embodiment, the invention of the apparatus has been describe, in which CPU 16 executes the program for performing a data reproducing operation, previously stored in the data reproducing apparatus. The apparatus may be modified such that CPU 16 of the apparatus executes the program for performing a data reproducing operation, stored in a memory into which the program can be written from an external medium. Further, the apparatus may be modified such that the apparatus is provided with a communication interface for accessing to a network such as the Internet and downloads from an external server through the communication interface and writes into a rewritable memory the program for performing a data reproducing operation, and CPU 16 executes the downloaded program. In this case, an invention of program maybe realized.
Number | Date | Country | Kind |
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2003-354681 | Oct 2003 | JP | national |