JPS60179963A - Digital audio disk player - Google Patents

Abstract

PURPOSE:To vary steps of sound signals to be reproduced by using a common oscillation circuit containing a signal processing circuit, a spindle control circuit and a D/A converting circuit as a frequency variable oscillation circuit. CONSTITUTION:When the frequency of a frequency variable oscillation circuit 8 is increased, a reference clock 5B of a spindle control circuit 7 is also increased. As a result, a spindle motor 2 is accelerated to increase the number of revolutions of a disk 1. In this case, a digital signal 5D which is sent to a D/A converting circuit 6 from a signal processing circuit 5 is increased for its information quantity per unit time by a degree equivalent to the rise of the frequency of the clock 5B. At the same time, the frequency of a deglitcher signal 5C is also increased. Therefore an audio signal is compressed in the same ratio toward a time axis. When the frequency of the circuit 8 is reduced, a signal 6A is expanded in the same ratio toward the time axis. In other words, the time axis can be compressed and expanded in proportion to the changing degree of frequency. Thus the step of the audio signal can be varied.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a digital audio disc player (hereinafter referred to as a disc) which makes it possible to vary the number of rotations of a digital audio disc (hereinafter referred to as a disc) to perform time axis companding of an analog signal. (hereinafter referred to as a DAD player).

Conventional configurations and their problems With the spread of software disks, DAD players are expected to make a big leap not only for consumer use but also for business use. Under these circumstances, karaoke players using DAD players are being developed as products compatible with karaoke players using conventional 8-track or compact cassette tapes.

Next, a conventional DAD player will be explained.

FIG. 1 shows the configuration of a conventional DAD player.

The RF signal 3A read from the disc 1 by the optical pickup 3 passes through an optical servo circuit and a preprocessing circuit 4 for digital signal processing, and is transmitted to four digital signals containing information recorded on the disc and a clock 4B for reading this. The signal is divided into two parts and input to the digital signal processing circuit 6. A digital signal processing circuit (hereinafter referred to as a signal processing circuit) corrects data that is erroneous due to scratches on the disk, rearranges the data to the correct time axis state, and sends the data to the DA conversion circuit 6. In the DA conversion, as shown in Fig. 2, for example, 16-bit parallel data 6D is input from the signal processing circuit 6 to the DA converter, and the stable part of the output 6C is extracted by the deglitch signal 6G: as shown by the solid line 6B. A signal as shown is obtained, then filtered and amplified and output as an audio signal 6A. On the other hand, the spindle motor control circuit 7 that rotates the disk uses six synchronizing signals detected from the digital signal 4A by the signal processing circuit and a reference clock 6.
B is compared in phase and the spindle motor 2 is driven by the error voltage. Further, the deglitch signal 5G of the DA conversion circuit 6 and the reference clock 5B of the spindle motor control circuit 7 are generated by frequency-dividing the drive clock of the signal processing circuit 6.

In such a conventional configuration, the drive clock of the signal processing circuit 6 is set to a fixed frequency using a crystal oscillator circuit, etc., and the frequencies of the reference clock 6B and deglitch signal 6C cannot be changed, and therefore, the frequency of the deglitch signal 6C cannot be changed. It was also not possible to change the pitch of an audio signal by changing its playback speed.

OBJECT OF THE INVENTION An object of the present invention is to provide a DA that can change the pitch of the audio signal being played back by changing the playback speed of the disc.
The purpose is to provide a D player.

Constituent Structure of the Invention The invention has a drive circuit that rotates a disk, a digital signal processing circuit that processes signals obtained from this disk, and a DA conversion circuit that converts the processed time signal into an analog signal, and each of these three circuits By breaking the common source oscillation circuit that generates the operating reference clock of the system and changing the oscillation frequency of this source oscillation circuit, it is possible to change the playback speed of the disk and time-base companding of the audio signal being played back. be.

DESCRIPTION OF THE EMBODIMENT FIG. 3 shows the configuration of an embodiment of the present invention. Reference numeral 8 denotes a variable frequency oscillation circuit which replaces the conventional original oscillation circuit, and is, for example, a voltage controlled oscillator. Also, 1 is a disk, 2 is a spindle motor, 3 is an optical pink amplifier, 4 is an optical servo circuit and a preprocessing circuit, 6 is a DA conversion circuit, and 7 is a spindle control circuit, which are the same configuration as the conventional example. . Note that 6 is a digital signal processing circuit, which has the same configuration as the conventional example except that the original oscillation circuit is changed from a fixed frequency circuit to a variable frequency oscillation circuit 8 (hereinafter referred to as VFO).

The operation of the DAD player of this embodiment configured as described above will be explained. First, the wave number of the VFO 8 is made the same as that of a conventional fixed frequency oscillator. This wave number is f.

shall be. In this case, there is no difference from a conventional DAD player. Next, suppose that the frequency of VFOa is increased by 6%, for example.

Then, since the reference clock 5B of the spindle control circuit 7 is created by dividing the frequency of this VFO clock, the reference clock 5B of the spindle control circuit 7
If the height is high, it will look like Figure 4.

At this moment, the rotational speed of the disk remains the same, so the repetition period of the synchronization signal 5A read from the disk does not change. Therefore, the system spindle motor 2 is accelerated by the error voltage resulting from the phase comparison.

As the rotational speed of the disk 1 increases, the period of the synchronization signal read from the disk gradually becomes shorter, and as a result, the rotational speed of the disk settles at 5% higher, i.e., /9r. At this time, the digital signal 6D sent from the signal processing circuit 6 to the DA conversion circuit 6 also has a larger amount of information per unit time as the frequency of the driving clock of the signal processing circuit 6 is increased by 5%. Deglitched signal 6C
The frequency will also increase by 6%. As a result, the DA conversion circuit as a whole takes a time ts corresponding to one sample in FIG.
The output 6B of the side-grid circuit, which is 5% shorter, is also compressed by 6% in the time axis direction. Therefore, the six audio signals are also compressed by 5% in the time axis direction. Conversely, if you lower the frequency of VFO8 by 5 inches, the audio signal will be 6A.
is expanded by 5 inches in the time axis direction. That is, v
By varying the frequency of yos, a time axis companding operation can be performed in comparison with the amount of change thereof.

As described above, according to this embodiment, by setting the common source oscillation circuit of the signal processing circuit, spindle control circuit, and DMU conversion circuit to VYO, it is possible to perform time axis companding of the audio signal to be reproduced. can be changed.

Effects of the Invention The present invention changes the rotational speed of the disk by changing the common fixed tube wave number oscillation circuit that generates the reference clock for the signal processing circuit, spindle control circuit, and DA conversion circuit to a variable frequency oscillation circuit. By changing the processing speed and the D/M conversion processing speed, it is possible to realize a DAD player that can compand the audio signal on the time axis and change the pitch.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional DAD player, Figure 2a
, b is a block diagram of the DA conversion circuit and a diagram for explaining its operation, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is a diagram for explaining the phase comparison. . DESCRIPTION OF SYMBOLS 1... Disk, 3... Optical pickup, 4... Pre-processing circuit, 6... Digital signal processing circuit, 6... D system conversion circuit, 8
・・・・・・Variable frequency oscillation circuit. Name of agent: Patent attorney Satoshi Nakao, G3, and 1 other person: Ku Soho ζQ. law law

Claims (1)

[Claims] A drive circuit that rotates a digital audio disc, a digital signal processing circuit that processes signals obtained from the digital audio disc, and a DA conversion circuit that converts the processed digital signal into an analog signal.
A common source oscillation circuit that generates an operating reference clock for each of these three circuits is provided, and by configuring this source oscillation circuit with a variable frequency oscillation circuit, time-base companding of the analog signal output of the DA conversion circuit is performed. A digital audio disc player characterized by: