JPS6010463A - Digital audio reproducing device - Google Patents

Abstract

PURPOSE:To reproduce easily an audio signal faithful to the original signal by providing a digital filter in the input side of a digital-analog converter prodived in a digital audio reproducing device and setting the phase rotation, which cancels the phase rotation of an analog low-pass filter provided in the output stage of a reproducing system, to this digital filter. CONSTITUTION:A phase rotation quantity which can cancel the phase rotation quantity of a low-pass filter 7 provided in the last stage is given to a digital filter 8. when a phase rotation quantity which is equal to the phase rotation quantity applied to a reproduced analog signal A by the low-pass filter 7 and has a rotation direction opposite to that of this phase rotation quantity is set to the filter 8, the phase rotation quantity applied to the audio signal by the filter 8 and that applied to the audio signal by the filter 7 are cancelled by each other, and thus, the reproduced audio signal an outputted from the low-pass filter 7 has the phase rotation corrected.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a digital audio playback device, and in particular to a digital audio playback device that prevents a decrease in faithful playback due to phase rotation applied to an audio signal played by a low noise filter used in a playback system. The present invention relates to a digital audio playback device.

Background Art In recent years, with the rapid development of electronic technology, there has been a trend toward digital recording of audio signals.
-i, Digital audio disc playback device (DAD)
) and POM processors have been developed.

FIG. 1 is a block diagram showing an example of a conventionally commonly used digital audio playback device. In the figure, 1 is a spindle motor that rotates a recording medium disk 2 on which audio signals are digitized and recorded so as to be read out optically, at a constant linear velocity; It is used to detect the reflected light of the emitted light beam.

The digital signal recorded on the disk 2 is read optically and output as a digital signal. Reference numeral 4 denotes a signal processing circuit which receives the digital signal supplied from the optical pickup 3 and performs various signal processing such as error correction and decoding into a digital audio signal. 5 is a digital Φ audio converter that converts the digital analog signal outputted from the signal processing circuit 4 into an analog value, and 6 is a digital-to-analog converter 5 that samples a stable part of the output signal outputted from the signal processing circuit 5 and converts it into an analog value. That person ξ-cha h7V that receives a wide PAM signal
This is an i-ronos filter, which removes undesired high-frequency noise contained in the PAM signal output from the anno-sorter 6, and outputs only the analog audio signal A as a reproduction signal.

In the digital audio disc playback device configured in this way, the spindle motor 1 rotates the disc 2, and the optical pickup 3 irradiates the surface of the disc 2 in this rotating state with a light beam and collects the reflected light. The digitally recorded information is read by the detection. A portion Vi of the digital signal output from the optical pickup 3 is fed back to the spindle motor 1 via a rotation control system (not shown), thereby controlling the rotation at a constant linear velocity. Further, the digital signal outputted from the optical pickup 3 is subjected to various signal processing such as error correction and signal processing in the signal processing circuit 4, and then directly converted into an analog signal in the digital-to-analog converter 5. be done. After the converted analog signal is sampled in the stabilized portion and equalized in time width in the anometry 6, the high-frequency noise is removed in the low-pass filter 7. Only audio signal A is output.

Therefore, in a device configured in this way.

Since it is intended to read out and reproduce audio signals recorded as digital signals on the disc 2 as a recording medium, it has the feature of being able to perform faithful reproduction.

However, in the apparatus having the above configuration, since a low-pass filter is used to remove the noise contained in the analog-converted audio signal, this low-pass filter imparts Km phase rotation to the audio signal. As a result.

The audio signal to which the phase rotation has been applied is different from the original sound signal recorded on the recording medium, and there is a problem in that the degree of faithful reproduction decreases accordingly.

DISCLOSURE OF THE INVENTION Accordingly, one object of the present invention is to correct the phase rotation applied to an audio signal by a low/-, Os filter provided in a reproduction system.

In order to achieve such an object, the present invention provides a digital filter on the input side of a digital-to-analog converter provided in a digital audio playback device, and a digital filter is provided on the output stage of the playback system for this digital filter. This is to set a phase rotation that cancels out the phase rotation of the analog low noise filter.

Therefore, in the digital audio playback device configured in this way, the phase rotation applied to the playback audio signal is corrected by .16 by the low-noise filter provided in the playback system, so that the audio signal is not recorded on the recording medium. It has the excellent effect of producing reproduced sound that is faithful to the original signal.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 2 is a block diagram showing an embodiment of a digital audio reproducing apparatus according to the present invention, and the same parts as those in the broom construction drawing are indicated using the same symbols. In the figure, 8 is a digital filter provided on the input side of the digital/analog converter 5. The digital filter 8 is provided with a phase rotation amount Vi that can cancel the phase rotation amount of the low-noise filter provided at the final stage.

In a device configured in this manner, the amount of phase rotation and the cutoff frequency of the digital filter can be easily varied independently, as is generally known. Then, if the amount of phase rotation of this digital filter 8 is set to a value that is 161- and the direction of rotation is opposite to the amount of phase rotation applied to the reproduced analog signal by the low/miss filter, The amount of phase rotation added to the audio signal and the amount of phase rotation added to the audio signal by the LONOMIS filter 7 cancel each other out, and accordingly, the reproduced audio signal output from the LONOMIS filter 7. becomes a signal whose phase rotation has been corrected. As a result, when the reproduced analog signal A is acoustically converted, one phase rotation is no longer included, and a phase table is no longer generated. This will allow playback.

In addition, in the above embodiment, the case where it is applied to a digital audio disc playback device has been described; however, the present invention is not limited to this, and can be applied to a device that plays back digital audio signals such as a digital audio tape playback device. It can be applied to everything.

As explained above, the digital audio playback device according to the present invention includes a digital filter provided on the input side of the digital-to-analog converter that converts the playback digital signal into an analog case, and adjusts the amount of phase rotation of the digital filter. Since it is set to a value that cancels out the amount of phase rotation of the low noise filter that is installed after the channel, the phase rotation of the reproduced audio signal is corrected and the signal is faithful to the original signal digitally recorded on the recording medium. Easy playback of audio signals

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional digital audio playback device, and FIG. 2 is a block diagram showing an embodiment of the digital audio playback device according to the present invention. l...Spindle motor, 2...Recording medium (disc), 3...Optical pickup, 4...Signal processing circuit, 5...Digital/analog converter, 6...Aperture, 7... ...Ronogus filter% 8...Digital filter. Applicant: ShinNippon Electric Co., Ltd.

Claims (1)

[Claims] (υ By reading an audio signal digitally recorded on a recording medium and supplying it to a digital-to-analog converter, it is converted into an analog signal, and by supplying this analog signal to an anomicha, In a digital audio playback device that samples a stable portion to produce a PAM signal with a uniform time width, and extracts this PAM signal through a rono-ξ filter to reproduce an audio signal from which high-frequency noise has been removed. , a digital filter is provided on the input side of the digital-to-analog converter, and this digital filter K fft
1. A digital audio playback device characterized in that a phase rotation amount is set to cancel the phase rotation of the low/R filter.