JP2001092476A - Sound reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an occurrence of failure in a digital signal processing part affected by electromagnetic noises in a sound reproducing device using digital signal processing(DSP) for processing sound signals. SOLUTION: An occurrence of abnormality is detected from the difference between the signals before and after digital signal processing by comparing them with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sound reproducing apparatus for performing digital signal processing.

[0002]

2. Description of the Related Art A DSP (Digital Signal Processor) used in an audio reproducing apparatus for performing arithmetic processing on a digital audio signal includes an arithmetic unit such as a product-sum arithmetic unit, a program controller, a data memory, a program memory, and the like. This is a semiconductor circuit that performs high-speed signal processing, and processes audio signals in response to program data and control signals from a control microcomputer. In the sound reproducing apparatus, signal processing such as control of sound signal characteristics using a DSP, for example, equalizer processing for changing frequency characteristics of a sound level, echo processing for adding reverberation, and volume control are performed.

On the other hand, in a sound reproducing apparatus using a DSP,
It is known that when electromagnetic noise, static electricity, or the like acts, the DSP may malfunction due to the destruction of data stored in a data memory, a program memory, or the like. In the sound reproducing apparatus, if the DSP malfunctions, abnormal sounds such as pop noises and oscillation sounds are generated, which gives the user discomfort.

For this reason, conventionally, data such as a processing program stored in a memory of a DSP is read periodically (every several seconds or the like) and collated with data that should have been stored. Has been detected. Then, when an abnormality is detected, for example, a mute circuit that shuts off the audio output of the sound reproducing device is operated to stop the audio output, thereby preventing generation of an abnormal sound.

[0005]

By the way, recently, coefficient data and the like for sound data processing have been increased for complicated sound control, and not only the coefficient data for sound data processing but also the operation program of the DSP are required. Since data is being stored, its data capacity is increasing. Therefore, the time for reading and collating these data has become longer, and for example, it may take as long as one second. Therefore, even if there is an abnormality in the DSP, it may take about one second until the abnormality is detected in some cases. In this case, an abnormal sound is output for about one second, which gives the user discomfort.

SUMMARY OF THE INVENTION The present invention solves such a problem, and even if a DSP operation failure occurs, a sound that can quickly prevent the generation of unpleasant abnormal sounds or the like that cause discomfort to the user. It is an object to realize a playback device.

[0007]

According to the present invention, there is provided an audio reproducing apparatus having a digital processing section for performing digital arithmetic processing on an audio signal. Addition means for adding the oscillation signal output by the oscillation means to the sound signal input to the digital processing unit, and a pass band for filtering the output signal of the digital processing unit is an oscillation frequency band of the oscillation means. A filter means, a comparison means for comparing an output signal of the filter means with an output signal of the oscillation means, and an abnormality detection means for detecting an abnormality of the digital processing section based on a comparison result of the comparison means. It is characterized by.

In a sound reproducing apparatus having a digital processing unit for performing digital arithmetic processing on an audio signal, a silence detecting means for detecting a silence state of an audio signal input to the digital processing unit; When the detection is made, output detection means for detecting an output signal of the digital processing section, and abnormality detection means for detecting an abnormality of the digital processing section based on a detection result of the output detection means are provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the configuration of an abnormality detecting circuit in a sound reproducing apparatus according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram illustrating a configuration of the abnormality detection circuit according to the first embodiment.

Reference numeral 13 denotes an oscillator for generating a digital signal of a predetermined non-audible sound (high frequency side). A method of converting a constant non-audible sound signal generated by a crystal oscillator or the like from analog to digital, a digital operation, and the like. This can be realized using a method of generating a similar signal by processing. An adder 14 adds an oscillating signal (digital) from the oscillating unit 13 to an acoustic signal input from the switching circuit 4 described later, and outputs the added signal to the digital processing unit 15. Reference numeral 15 denotes a digital processing unit that performs digital arithmetic processing on an input acoustic signal in order to perform signal processing such as equalizer processing for changing frequency characteristics, echo processing for adding reverberation, and volume control, and a digital signal processor (DSP). ). 16
Is a bandpass filter for filtering out an inaudible signal in the oscillation frequency band of the oscillating unit 13 from the output signal of the digital processing unit 15, and is realized by a digital arithmetic circuit. Note that an audio signal having an audible frequency does not pass through the bandpass filter 16. Reference numeral 17 denotes a subtracter for subtracting the digital value from the oscillation unit 13 from the signal input from the bandpass filter 16,
It is composed of a digital operation circuit, and outputs a signal of a subtraction result to the control unit 12. 18 removes the signal of the oscillation frequency band of the oscillation unit 13 from the output signal of the digital processing unit 15,
A filter (band cut filter or low-pass filter) that outputs only signals in the audible frequency band, and is realized by a digital operation circuit.

Next, the operation will be described. The adder 14 adds the digital audio signal input from the switching circuit 4 to the oscillation unit 13.
Are added. Next, the acoustic signal to which the oscillation signal has been added is subjected to predetermined arithmetic processing by the digital processing unit 15, and a sound field is given to the acoustic signal,
Adjustment of frequency characteristics and the like are performed. Then, the output signal of the digital processing unit 15 is output to a digital-to-analog converter (DAC) 6, which will be described later, after the oscillation signal of the oscillation unit 13 added by the filter 18 is removed. The output signal of the digital processing unit 15 is such that an audible frequency band signal is removed by the bandpass filter 16 and a signal corresponding to the oscillation signal of the oscillation unit 13 is output. Since the digital processing unit 15 generally processes signals in the audible frequency band, the oscillating signal (non-audible frequency band) of the oscillation unit 13 is not changed by the digital processing unit 15. The signal output from the bandpass filter 16 is subtracted by the subtractor 17 from the signal from the oscillation unit 13 and output to the control unit 12. The result of the subtraction by the subtractor 17 is a predetermined value (0 in this example) when the digital operation processing is normal, and an unexpected value (in this example, the value from 0 in this example) when an abnormality occurs. From the distance). That is, when abnormal processing is performed in the digital processing unit 15, for example, when the storage data stored in the RAM or ROM of the internal circuit of the DSP is damaged or the internal circuit is faulty, the digital processing unit 15 Abnormal processing is performed at 15 and abnormal arithmetic processing is also performed on the signal in the non-audible frequency band, the signal changes, and the subtractor 17 outputs a signal other than a predetermined value (0 in this example). A signal is output, and the occurrence of an abnormality is detected. In this example, the abnormality detection circuit is configured by a digital circuit, but the abnormality detection circuit can be similarly realized by an analog circuit. When the abnormality detection circuit is configured by a digital circuit, it can be entirely configured by a DSP.

Next, an audio reproducing apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 2 is a configuration diagram illustrating a configuration of the sound reproduction device according to the embodiment of the present invention, and illustrates an example in which the abnormality detection circuit illustrated in FIG.

Reference numeral 1 denotes a CD player for reproducing a signal recorded on a compact disk (CD), and outputs a digital sound signal. Reference numeral 2 denotes a cassette player for reproducing a signal recorded on a cassette tape, and outputs an analog sound signal. An analog-to-digital converter (A) 3 converts an input analog signal into a digital signal and outputs the digital signal.
DC). Reference numeral 4 denotes a switching circuit for selecting a signal on the player side selected for reproduction from an output signal (a signal converted into a digital signal by the ADC 3) of the CD player 1 or the cassette player 2 and outputting the signal to a subsequent stage. And a relay. Reference numeral 5 denotes a DSP that performs high-speed arithmetic processing on the digital audio signal output from the switching circuit 4, is configured by a semiconductor integrated circuit, stores therein a processing program and the like, and records various coefficients. Further, a memory such as a RAM and a ROM for temporarily storing a calculation value and the like during the calculation processing is provided. The DSP 5 applies a predetermined frequency characteristic to the audio signal by digital arithmetic processing, and performs sound field control (for example, reproduces a sound field space of a concert hall or the like) by delay processing and level adjustment processing for the delayed signal and the like. . In addition, by the arithmetic processing of the DSP 5, the loudness adjustment, the bass treble adjustment, the low frequency correction, the equalizer processing,
It is also possible to perform volume adjustment processing, filter processing (such as noise removal), and the like. Reference numeral 6 denotes a digital-to-analog converter (DAC) that converts an output signal (digital signal) of the DSP 5 into an analog signal and outputs the signal as an audio signal. Reference numeral 7 denotes a mute circuit that controls connection and disconnection of the audio signal output from the DAC 6 to the amplifier 8, and includes a switching transistor and the like. Reference numeral 8 denotes an amplifier for amplifying the power of the audio signal output from the mute circuit 7, and the amplified signal is output to the speaker 9 to reproduce sound. 1
Reference numeral 0 denotes an operation unit for performing various operations (selection of frequency characteristics of an audio signal, selection of a sound field, adjustment of a volume, selection of a player to be reproduced, and the like) of the audio reproduction device, and is configured by a push switch or the like. Reference numeral 11 denotes a display for displaying the signal processing status and the like of the sound reproducing apparatus, and is constituted by a liquid crystal display or the like. And
For example, a graph display showing a frequency characteristic given to the acoustic signal, an alarm when an abnormality occurs, and the like are displayed. 12
Is a control unit that performs input processing of signals from each unit of the sound reproducing apparatus and operation control of each unit, and is configured by a microcomputer. Specifically, control of the disconnection state of the mute circuit 7, control of the switching state of the switching circuit 4, control of the display of the display 11, and control of the display of the DSP 5 are performed in accordance with the operation state of the operation unit 10 and the abnormality detection signal from the DSP 5. Operation control and the like are performed. The control of the DSP 5 is performed by setting a coefficient used by the DSP 5 for calculation and by writing an operation program of the DSP 5.

Next, the operation of the sound reproducing apparatus will be described. The digital audio signal output from the switching circuit 4, that is, the digitized signal of the output signal of the CD player 1 or the cassette player 2 whose reproduction is selected by the operation of the operation unit 10, is input to the DSP 5. The acoustic signal is processed by the DSP 5 based on control data such as coefficients from the control unit 12 and output to the DAC 6. In the DAC 6, the digital sound signal is converted into an analog signal and output to the mute circuit 7. The sound signal input to the mute circuit 7 is
Transmission to the subsequent amplifier 8 is controlled in accordance with the mute control signal from the control unit 12, and is output to the amplifier 8 during normal times, and the sound signal is cut off when the mute control signal is input from the control unit 12. The audio signal output from the mute circuit 7 is power-amplified by the amplifier 8 and output from the speaker 9 as sound.

Further, if an abnormality occurs in the DSP 5 due to the destruction of data of the DSP 5 due to the influence of noise or static electricity, etc., the abnormality detection circuit described with reference to FIG. Outputs an abnormal signal to the control unit 12. Then, the control unit 12 outputs a signal to cut off the sound output to the mute circuit 7 to stop the sound output of the sound reproducing device, and causes the display 11 to display an alarm.

Next, the configuration of the abnormality detection circuit in the sound reproducing apparatus according to the second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 3 is a configuration diagram illustrating a configuration of an abnormality detection circuit according to the second embodiment. Note that the same components as those shown in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. Further, the abnormality detection circuit is applied to the sound reproducing device of FIG. 2, and outputs a signal for abnormality detection to the control unit 12.

Reference numeral 19 denotes a silence detecting unit for judging the presence or absence of the input of the acoustic signal (whether or not there is silence), and is constituted by a comparator for judging whether or not the input signal level is 0. Then, the silence identification signal is output to the control unit 12. Reference numeral 20 denotes a reference signal to be generated when there is no sound in a normal state (0 in this example: a process of adding a frequency characteristic or a sound field to a signal when there is no sound) by outputting an output signal from the digital processing unit 15. The comparison unit generates a comparison signal, and the generated comparison signal is output to the control unit 12.

Next, the processing performed by the control unit 12 will be described with reference to FIG.
This will be described with reference to FIG. FIG. 4 is a flowchart illustrating a process performed by the control unit 12 according to the second embodiment of the present invention.

This process is repeatedly performed while the sound reproducing apparatus is running, together with the processing for another sound reproducing apparatus. In step S1, a signal from the silence detection unit 19 is input, and the process proceeds to step S2. In step S2, it is determined whether or not a silent state is detected based on a signal from the silent state detecting unit 19. If the state is a silent state, the process proceeds to step S3. In step S3, a comparison signal indicating whether or not a signal to be detected during silence output from the comparison unit 20 is input, and the process proceeds to step S4. In step S4, it is determined whether or not the operation of the digital processing unit 15 is abnormal based on the comparison signal. If the operation is abnormal, the process proceeds to step S5. Since the process in step S4 is performed in the silent state in step S2, when the signal to be detected in the silent state is not detected from the comparing unit 20 (when other signals are detected), it can be determined that the abnormality is abnormal. . In step S5, a mute signal for cutting off the sound output is output to the mute circuit 7 (shown in FIG. 2), and the process proceeds to step S6. When a mute signal is output to the mute circuit 7, the mute circuit 7 enters a signal cutoff state, and no audio signal is input to the amplifier 8, so that sound output from the speaker 9 is stopped.
In step S6, a display indicating that the operation of the digital processing unit 15 is abnormal is displayed on the display unit 11, and the process ends.

By performing the processing as described above, when the sound signal input to the digital processing unit 15 is in a silent state, the signal (silent state) that should be originally output in the silent state is:
Depending on whether or not the data is output from the digital processing unit 15, the occurrence of an abnormality such as the destruction of the stored data in the digital processing unit 15 or the occurrence of a failure in the semiconductor circuit element is detected. Also,
When an abnormality occurs, the sound output from the speaker 9 is stopped, and the display 11 indicates that the abnormality has occurred.
That is, the digital processing unit 15 performs predetermined digital arithmetic processing on the input audio signal. With respect to this silence signal, the expected output (silence) of the digital audio signal can be expected. However, when the sound signal is a silent signal and an expected output signal (silence) is not obtained, it is determined that an abnormality has occurred in the digital arithmetic processing in the digital processing unit 15. It is. In addition, when an abnormality occurs in the operation of the digital processing unit 15, the sound output from the speaker 9 is stopped, so that no noise or noise is output from the speaker 9, and
It is possible to prevent the user from feeling uncomfortable while using the sound reproducing device.

As described above in detail, according to each embodiment of the present invention, during operation of the sound reproducing apparatus, the abnormality is detected by comparing the signals before and after the digital arithmetic processing. Even if it occurs, the occurrence of abnormality can be detected instantaneously, the output of the abnormal sound can be made extremely short, and the discomfort felt by the user with respect to the output of the abnormal sound can be reduced. Further, according to the second embodiment of the present invention, an abnormality is detected by catching a point in time when the acoustic signal during operation of the sound reproducing device is a silent signal, so that the oscillating unit for abnormality detection and the like are provided. It is unnecessary and can simplify the circuit configuration,
The cost of the abnormality detection circuit can be reduced.

[0022]

As described above in detail, according to the present invention, the abnormality of the digital processing unit is detected by comparing the signals before and after the digital operation processing on the audio signal. Abnormality can be quickly detected, and generation of an abnormal sound or the like that is unpleasant for the user can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an abnormality detection circuit according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of an audio reproduction device according to a first embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a configuration of an abnormality detection circuit according to a second embodiment of the present invention;

FIG. 4 is a control unit 12 according to a second embodiment of the present invention.
6 is a flowchart showing the processing performed by the first embodiment.

[Description of Signs] 1 ... CD player 4 ... Switching circuit 5 ... DSP 6 ... DAC 7 ... Mute circuit 8 ... Amplifier 11 ... Display unit 12 ... Control unit 13 ...・ Oscillator 14 ・ ・ Adder 15 ・ ・ Digital processor 16 ・ ・ Band filter 17 ・ ・ Subtracter 19 ・ ・ Silence detector 20 ・ ・ Comparator

Claims (2)

[Claims] 1. An audio reproducing apparatus having a digital processing unit for performing digital arithmetic processing on an audio signal, comprising: an oscillating unit for outputting an audible signal of an inaudible frequency; and an oscillating signal output by the oscillating unit, the digital processing unit Adding means for adding to an audio signal input to the filter means; filter means having a pass band for filtering an output signal of the digital processing unit being an oscillation frequency band of the oscillating means; output signal of the filter means; and the oscillating means A sound reproducing apparatus comprising: a comparing unit that compares output signals of the digital processing unit; and an abnormality detecting unit that detects abnormality of the digital processing unit based on a comparison result of the comparing unit. 2. A sound reproducing apparatus having a digital processing unit for performing digital arithmetic processing on an audio signal, wherein: a silence detection unit for detecting a silence state of an audio signal input to the digital processing unit; A sound detecting means for detecting an output signal of the digital processing unit when detecting the sound, and an abnormality detecting means for detecting an abnormality of the digital processing unit based on a detection result of the output detecting means. Playback device.