JPH0621084Y2 - Digital audio recording medium reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a digital audio recording medium reproducing apparatus such as a digital audio disc player.

BACKGROUND ART In a digital audio recording medium reproducing apparatus, as shown in FIG. 1, a digital signal read by a pickup 1 from a recording medium (not shown) is corrected by a digital processing circuit 2 to be D / A (digital / analog). ) It is supplied to the converter 3. The output analog signal of the D / A converter 3 is supplied to an LPF (low pass filter) 4 and an audible frequency component is extracted. The output signal of the LPF 4 is the reproduction output, but the high-frequency component of the audible frequency band is reduced by the de-emphasis circuit 5 only when the DIMP signal is detected from the recording medium. In addition, DEM
The P signal is a signal indicating that the high frequency component of the signal is emphasized by the pre-emphasis circuit at the time of recording and is recorded on the recording medium together with the audio signal.

By the way, such a digital audio recording medium reproducing apparatus normally has an PLAY (reproduction mode),
In some cases, it has a FF (fast-forward) mode or a REV (fast-reverse) mode, and further, a special operation for automatically switching between these operation modes to obtain an analog reproduced sound can be instructed with a single switch. Many.

For example, there is a special operation in which a plurality of songs recorded on a recording medium are reproduced every few seconds. The reproduced sound in this special operation becomes discontinuous due to the fast-forward period, that is, the jump periods A and B, as shown in the waveform of FIG. Since the waveforms in the jump periods A and B have steep characteristics, the above L
When it passes through the PF, it becomes steeper as shown in Fig. 2 (b) and becomes noise. That is, as shown in FIG. 2 (a), since the read signal immediately before the jump suddenly changes to the read signal after the jump, the change signal is not included in the recording medium, for example, non-recording at 20 KHz or more. It occurs that frequency components are included. When a signal including such a non-recording frequency component is supplied to the LPF 4, the non-recording frequency component is changed to the LPF 4.
Since the signal waveform shown in FIG. 2 (a) cannot be obtained as it is from the output signal of the LPF4, the signal corresponding to the abrupt change part causes ringing and is changed to the signal shown in FIG. 2 (b). It becomes the indicated noise signal. This is the same as when the impulse signal is supplied to the LPF, since the impulse signal contains almost all frequency components, the output signal of the LPF causes ringing and becomes an oscillating waveform. Therefore, conventionally, at the time of such a special operation command, the output level is digitally reduced by supplying a level control signal to the digital processing circuit 2 as shown in FIG. 1, or the signal level after D / A conversion is performed. Was directly reduced to apparently reduce the noise component.

However, just reducing the output level during the special operation period does not improve the S / N ratio, resulting in a difficult-to-hear reproduced sound.

SUMMARY OF THE INVENTION Therefore, the purpose of the present invention is to perform S / S during the special operation period.
It is an object of the present invention to provide a digital audio recording medium reproducing apparatus which improves the N ratio and improves the reproduced sound.

A reproducing apparatus for a digital audio recording medium according to the present invention comprises a digital audio signal and a digital audio signal from an information recording medium carrying a digitized audio signal in which a high frequency component is emphasized and a first emphasis control signal indicating the high frequency component emphasis time. Reading means for reading and outputting the 1st emphasis control signal, conversion means for outputting an analog audio signal according to the digital audio signal from the reading means, and signal generating means for outputting the second emphasis control signal during the jump operation period. ,
De-emphasis means for reducing the high frequency component level of the analog audio signal when at least one of the first and second enhancement control signals is being output.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

In FIG. 3, the same parts as in FIG. 1 are designated by the same reference numerals, and D detected by the digital processing circuit 2 is the same.
The EMP signal is supplied to the de-emphasis circuit 5 via the OR circuit 6. On the other hand, the keyboard 7 is PLAY, FF
A switch for instructing various operation modes such as the above and special operations is provided, and a control circuit 8 including a microcomputer is connected to the output of the keyboard 7. The control circuit 8 generates various control signals according to an operation command from the keyboard 7, and one of them is a special operation signal generated during a special operation. This special operation signal is passed through the OR circuit 6 and the de-emphasis circuit 5 as in the DIMP signal.
Is supplied to.

In the digital audio recording medium reproducing apparatus according to the present invention having such a configuration, the digital signal obtained from the pickup 1 is corrected by the digital processing circuit 2 and supplied to the D / A converter 3 as in the conventional case. Then, the audio frequency component of the output analog signal of the D / A converter 3 is obtained from the LPF 4 as a reproduction output. The de-emphasis circuit 5 is normally in the inactive state, and the LPF 4
The output of is output as is.

When the digital processing circuit 2 detects the DEM signal from the signal obtained from the pickup 1 in the PLAY mode, the DEM signal is supplied to the de-emphasis circuit 5 via the OR circuit 6 as the first emphasis control signal. The de-emphasis circuit 5 reduces the high frequency component of the output signal in the audible band of the LPF 4 according to the DEM signal and outputs it. The audio signal thus obtained has the same frequency characteristic as that at the time of recording.

On the other hand, during the special operation, the control circuit 8 generates a special operation signal in response to the operation command signal of the keyboard 7, and the special operation signal is supplied to the de-emphasis circuit 5 as the second emphasis control signal via the OR circuit 6. It The de-emphasis circuit 5 reduces the high-frequency component of the output signal of the LPF 4 and outputs it in the same manner as when the DEM signal is supplied in response to the special operation signal.

As a result, during special operation, as shown in Fig. 4 (a), the LPF
When noises C and D occur in the portion corresponding to the jump operation period of the output waveform 4 of FIG. 4, the noise is reduced by the de-emphasis circuit 5 as shown in FIG. 4 (b).

Effects As described above, according to the digital audio recording medium reproducing apparatus of the present invention, since the high frequency component of the analog audio output, that is, the noise portion is reduced during the jump operation period, the S / N ratio in the special operation is improved. be able to. It should be noted that since the high frequency components are cut, some deterioration of the sound quality cannot be avoided, but since the reproduced sound becomes better overall due to the improvement of the S / N ratio, there is no problem in the special operation. .

Further, in the digital audio recording medium reproducing apparatus of the present invention, the de-emphasis circuit can be used also as the high frequency component reducing means as in the above-mentioned embodiment, and in this case, the above-mentioned effect can be obtained with a simple configuration. You can do it.

Further, the digital audio recording medium reproducing apparatus of the present invention can be applied not only to a digital audio disc player and a PCM type tape deck, but also to a case where a sound output is obtained during a special operation of a video disc player.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a conventional example of a digital audio recording medium reproducing apparatus, FIG. 2 is a waveform diagram showing the operation of the apparatus of FIG. 1, and FIG. 3 is an embodiment of the present invention. Block diagram showing
FIG. 4 is a block diagram showing the operation of the apparatus shown in FIG. Description of symbols of main parts 1 ... Pickup 2 ... Digital processing circuit 3 ... D / A converter 4 ... LPF 5 ... De-emphasis circuit 6 ... OR circuit

Claims (1)

[Scope of utility model registration request] 1. A digital audio signal and a first emphasis control signal from an information recording medium carrying a digitized audio signal in which a high frequency component is emphasized and a first emphasis control signal indicating the time when the high frequency component is emphasized. Reading means for reading and outputting the signal, converting means for outputting an analog audio signal according to the digital audio signal from the reading means, signal generating means for outputting a second emphasis control signal during a jump operation period, and And a de-emphasis means for reducing the high frequency component level of the analog audio signal when at least one of the first and second enhancement control signals is being output.