Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
2000-08-17
2004-02-17
Tran, Thang V. (Department: 2653)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S047320
Reexamination Certificate
active
06693866
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to optical disk recording apparatus for recording audio signals onto optical disks in digital representation. More particularly, the present invention relates to an improved optical disk recording apparatus which is arranged to temporarily store input digital audio signals into a buffer memory in synchronism with clock pulses reproduced from the input digital audio signals and then read out, from the buffer memory, the digital audio signals in synchronism with reference clock pulses, generated by an internal reference clock pulse generator, to thereby record the read-out audio signals onto an optical disk at a same sampling rate as the input digital audio signals, and which can appropriately reduce a wait time from a time point when an instruction for terminating the recording is given to a time when the recording is actually terminated in response to the instruction.
As an example of the optical disk recording apparatus for recording audio signals onto an optical disk in digital representation, the audio CD (Compact Disc) recorder has been put to actual use, which is constructed to record input audio signals onto a CD-R (CD Recorder/CD Write-Once) or CD-RW(CD Rewritable) disk in a CD format. Such an audio CD recorder accepts input of both analog audio signals and digital audio signals. When the input of digital audio signals has been selected, the audio CD recorder generally records the input digital audio signals onto an optical disk after having converted the sampling rate of the input digital audio signals to the CD sampling rate of 44.1 kHz. If the sampling rate of the input digital audio signals is the same as the CD sampling rate (e.g., if the input digital audio signals have been received from a CD), the input digital audio signals can be recorded as the so-called “CD direct recording” without the sampling rate conversion. In the CD direct recording, 44.1 kHz clock pulse signals are first reproduced from the input digital audio signals. In synchronism with the thus-reproduced clock pulse signals, the input digital audio signals are temporarily written into a buffer memory and then the digital audio signals are read out from the buffer memory and recorded onto the optical disk. At that time, the clock pulses are frequency-divided to create 22.05 kHz clock pulse signals, and rotation of a spindle motor driving the optical disk is controlled in a PLL (Phase-Locked Loop) fashion so that a wobble frequency detected from the optical disk coincides with the frequency of the thus-created clock pulse signals. Also, the reproduced clocks are frequency-multiplied and then fed to a recording strategy circuit so as to finely adjust/control an irradiation time and irradiation start timing of a recording laser light beam.
However, because the above-mentioned conventional recording technique operates the recording strategy circuit by use of the reproduced clocks having a relatively poor accuracy (i.e., having relatively great time axial variations), the irradiation time and irradiation start timing of the recording laser light beam tend to be finely adjusted with a very poor accuracy relative to predetermined adjustment amounts, which would unavoidably result in degradation of recording signal quality and increased reading errors at the time of reproduction. Thus, it is now being proposed that the CD direct recording be carried out on the optical disk using, in place of the reproduced clock pulses, reference clock pulses generated by an internal reference clock pulse generator such as a crystal oscillator. More specifically, according to the proposed recording scheme, the 44.1 kHz clock pulse signals are first reproduced from the input digital audio signals so that the input digital audio signals are temporarily written into the buffer memory in synchronism with the reproduced clock pulses, and then 44.1 kHz clock pulse signals are created on the basis of the reference clock pulses generated by the internal reference clock pulse generator. Thence, the digital audio signals are read out from the buffer memory and recorded onto the optical disk in synchronism with the 44.1 kHz clock pulse signals based on the reference clock pulses. At that time, 22.05 kHz clock pulse signals are also created on the basis of the reference clock pulses, and the rotation of the spindle is controlled in the PLL fashion so that the wobble frequency detected from the optical disk coincides with the frequency of the 22.05 kHz clock pulse signals. In addition, the recording strategy circuit is controlled on the basis of the reference clock pulses so as to control the irradiation time and irradiation start timing of the recording laser light beam. By thus operating the recording strategy circuit on the basis of the highly accurate reference clock pulses, the proposed recording scheme provides for recording with high recording signal quality and hence reproduction with minimized reading errors.
But, because the reproduced clock pulses used to temporarily write the input digital audio signals into the buffer memory and the reference clock pulses used to read out the digital audio signals from the buffer memory are not synchronous with each other in the proposed recording scheme, and if the speed of reading from the buffer memory is higher than the speed of writing into the buffer memory, then the buffer memory would run out of data to cause a so-called “buffer underrun” situation and thus the recording fails. To prevent the undesired buffer underrun, it is necessary to start the recording onto the optical disk only after a sufficient quantity of data have been stored in the buffer memory. For example, in the case of a CD whose recording length is 80 min. and for which the reproduced clock pulses differ from the reference clock pulses by 300 PPM, the following time difference would result between the time for writing all the data into the buffer memory and the time for reading all the data from the buffer memory:
300 (PPM)×80 (min).×60 (sec.)=1.44 (sec.)
Thus, in this case, there arises a need to start the recording onto the optical disk 1.44 sec. after the writing of the input signals into the buffer memory has been initiated in response to a user's instruction for starting the recording, as illustrated in FIG.
2
.
Further, according to the above-mentioned CD format, an inter-music-piece blank signal, indicative of a blank segment between adjoining music pieces (silent signal), can be recorded at the beginning of each track (e.g., each music piece) in a program area, by setting an index of Q subcode to “0”. Each inter-music-piece blank signal has one of predetermined lengths, i.e. two or more seconds for the first track and zero (i.e. no blank segment between the music pieces, is also selectable) and more seconds for second and succeeding tracks. In
FIG. 3
, there is shown an exemplary manner in which the inter-music-piece blank signals are recorded onto an optical disk. When a music piece (a single track) is to be recorded onto a CD-R or CD-RW disk with an inter-music-piece blank segment, the inter-music-piece blank signal is first recorded onto the optical disk and the music piece is recorded immediately after the recording of the inter-music-piece blank signal (namely, with one stroke). Assuming that the recording onto the optical disk is started 1.44 sec. after the user gives a recording start instruction to initiate writing of input signals into the buffer memory similarly to the above-mentioned, the recording start of the music piece would be delayed more than 1.44 sec. from the user's recording start instruction because the recording onto the optical disk is started after the inter-music-piece blank signal recording.
FIG. 4
shows a situation in which the inter-music-piece blank signal is recorded for two seconds in the above-mentioned manner. Namely, the recording onto the optical disk is started 1.44 sec. after the user gives the recording start instruction to initiate the writing of the input signals into the buff
Pillsbury & Winthrop LLP
Tran Thang V.
Vuong Bach
Yamaha Corporation
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