JP2009071743A - Sound output device, sound output program and sound output method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound output device, a sound output program and a sound output method that suppress detection misrecognition of a DC offset, even when an apparatus for extension is connected in a BTL amplifier that detects the DC offset signals of an amplification part and prevents damages to the voice coil of a loudspeaker, or the like. <P>SOLUTION: The sound output device 100 is provided with a volume adjusting part 110 for adjusting the volume of audio signals, an amplification part 120 for amplifying the audio signals and transmitting DC offset detection signals, when the DC offset is detected, and a control part 130 for monitoring the audio level of the adjusted audio signals and changing the drive state of the amplification part 120, corresponding to the audio level when receiving the DC offset detection signals. When the connection of the apparatus 200 for extension is detected, the control part 130 switches the audio signals to pass via the apparatus 200 for extension and stops the monitoring of the audio level. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an audio output technology, and more particularly, to a malfunction suppression technology for an amplification unit built in an audio output device.

  In the field of audio technology, various studies have been conducted to suppress speaker damage. For example, the BTL amplifying device disclosed in Patent Document 1 detects a DC offset signal of an amplification part and uses this detection result to prevent damage to a voice coil of a speaker.

  In addition, a technique for preventing such misdetection of a DC offset signal is also known. FIG. 6 is a functional block diagram showing a main configuration of a car audio control device (hereinafter referred to as an audio output device) 300 including the technology. According to the figure, the level of audio signals (hereinafter referred to as audio levels) for the front (driver's side, passenger's side) and rear (rear seat side) is monitored by a control unit 330 such as a CPU, When the DC offset detection signal is detected, it is determined whether there is an error in detection of the DC offset detection signal according to the audio level.

JP 2000-174571 A

  By the way, an expansion device for enhancing an audio function or the like may be connected to the BTL amplifying device or the audio output device 300 described above. FIG. 7 is a functional block diagram showing a main configuration of the audio output device 300 when the expansion device 400 is connected. When the expansion device 400 is connected to the audio output device 300, as shown in FIG. 7, the switch SW4 connected to the first terminal a is connected to the second terminal b, and the closed switch SW5 is opened. Since the setting value set in the front volume 311 from the user via the operation unit is reset to a fixed value, the amplification unit 320 is transmitted from the volume adjustment unit 310 and passes through the expansion device 400. Receive an audio signal.

  In this case, although the audio level of the front audio signal is monitored by the control unit 330, the audio level is fixed, so that the detection error is detected in relation to the DC offset detection signal detected by the level detection unit 313. May occur. In addition, as disclosed in Patent Document 1, it may be possible to suppress detection error by forming a capacitor between the electronic volume and the amplification part. However, since the number of parts increases, the manufacturing cost and the sound output device It is not desirable from the viewpoint of miniaturization.

  The present invention has been made in view of such circumstances, and an audio output device, an audio output program, and an audio output in which false detection of DC offset is suppressed even when an expansion device is connected to the audio output device. It aims to provide a method.

The present invention relates to a volume adjusting unit that adjusts the volume of an audio signal, an amplifier that amplifies the audio signal and transmits a DC offset detection signal when a DC offset is detected, and an audio level of the adjusted audio signal. And a control unit that changes a driving state of the amplification unit according to the audio level when the DC offset detection signal is received, and the control unit connects the expansion device. When detected, the audio output device switches the audio signal via the expansion device and stops monitoring the audio level.
According to this configuration, when the expansion device is connected to the audio output device, monitoring of the audio level is stopped.

In the above invention, the volume adjusting unit includes a front seat side volume adjusting unit and a rear seat side volume adjusting unit in a vehicle interior, and the control unit detects a front portion when detecting the connection of the expansion device. It can be set as the structure which stops the monitoring of the audio level adjusted with the adjustment part for seat sides.
According to this configuration, when the expansion device is connected to the audio output device, monitoring of the audio level of the audio signal adjusted by the front seat adjustment unit stops.

In the above invention, the control unit may be configured to turn off the power of the amplification unit when the audio level is equal to or lower than a threshold value.
According to this configuration, the audio output device turns off the power of the amplifying unit when the audio level is equal to or lower than the threshold value.

The present invention also provides a computer, a volume adjusting unit that adjusts the volume of an audio signal, an amplifying unit that amplifies the audio signal and transmits a DC offset detection signal when a DC offset is detected, and the adjusted audio When the audio level of the signal is monitored and a DC offset detection signal is received, it functions as a control unit that changes the driving state of the amplification unit according to the audio level, and the control unit detects the connection of the expansion device In this case, the audio output program is characterized in that the audio signal is switched via the expansion device and the monitoring of the audio level is stopped.
According to this configuration, when the expansion device is connected to the audio output device, monitoring of the audio level is stopped.

The present invention also adjusts the volume of the audio signal, amplifies the audio signal, transmits a DC offset detection signal when a DC offset is detected, monitors the audio level of the adjusted audio signal, and detects the DC offset. When the detection signal is received, the drive state of the amplification unit is changed according to the audio level, and when the connection of the expansion device is detected, the audio signal is switched via the expansion device and monitoring of the audio level is stopped. This is an audio output method characterized by:
According to this configuration, when the expansion device is connected to the audio output device, monitoring of the audio level is stopped.

  According to the present invention, it is possible to suppress misdetection of DC offset even when an expansion device is connected to the audio output device.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a functional block diagram showing a main configuration of the audio output device 100 and the like according to the embodiment of the present invention, and FIG. 2 is a functional block diagram showing a hardware configuration of the audio output device 100.

First, the audio output device 100 will be described.
As shown in FIG. 1, the audio output device includes a volume adjustment unit 110, an amplification unit 120, a control unit 130, various switches SW1 to SW3, and the like. Examples of the audio output device 100 include a head unit in the car audio field. The name of the audio output device is not particularly limited, and may be, for example, a main unit, a center unit, or the like.

  The volume adjustment unit 110 is configured with, for example, an electronic volume, and adjusts the volume (volume) of an audio signal related to audio such as a CD or radio according to an operation from a user. As shown in FIG. 1, the electronic volume for car audio includes a front volume 111 as a front seat volume control unit, a rear volume 112 as a rear seat volume control unit, and the like. . Thereby, the fader adjustment which adjusts the speaker volume before and behind the vehicle interior becomes possible.

  Although not shown in FIG. 1, if necessary, a subwoofer adjustment function for adjusting the subwoofer output, a bass (bass) adjustment function for adjusting the strength of the low frequency range, and a treble (high tone) for adjusting the strength of the high frequency range. It is desirable to configure an adjustment function and a balance adjustment function for adjusting left and right speaker volumes. When the volume and the above-described functions are set by operation by the user, the setting values are set by the control unit 130 in the front volume 111, the rear volume 112, and the like.

  Furthermore, the volume adjustment unit 110 includes a level detection unit 113 and a switch SW3. Note that these are not limited to installation in the sound volume adjustment unit 110 as long as they are in the audio output device 100.

  The level detection unit 113 detects the audio level of the audio signal adjusted by the front volume 111 and the rear volume 112, and outputs these audio levels to the control unit 130 as an audio level detection signal.

  The switch SW3 is a switch for switching between detection of the audio level and stop of the detection. When the switching operation of the switch SW3 is controlled by the control unit 130 and an expansion device 200 described later is connected, the switch SW3 is turned off, and the level detection unit 113 stops detecting the audio level. It should be noted that a switch for switching between detection of audio levels for the rear as well as for the front and stop of the detection may be configured in the volume adjustment unit 110, but only for the front from the viewpoint of reducing the number of parts. desirable.

  The amplifying unit 120 is composed of, for example, a power amplifier and amplifies the audio signal. The amplified audio signal is output from the speaker 250. In addition, the amplifying unit 120 includes a voltage detection circuit (not shown), detects a voltage difference between the DC voltage (DC voltage) between the positive electrode and the negative electrode, and a DC offset occurs when the voltage difference exceeds a predetermined value. Judgment is made and a DC offset detection signal is output to the control unit 130.

  The switch SW1 is a changeover switch for switching to connection to the first terminal a or connection to the second terminal b. The switching operation of the switch SW1 is controlled by the control unit 130, and when the switch SW1 is connected to the first terminal a, the front audio signal is directly transmitted to the amplifying unit 120. When the switch SW1 is connected to the second terminal b, the front audio signal is transmitted to the amplifying unit 120 via the expansion device 200.

  The switch SW2 is a switch for switching between transmission of a rear audio signal and stop of the transmission. When the switching operation of the switch SW2 is controlled by the control unit 130 and an expansion device 200 described later is connected, the switch SW2 is turned off and transmission of the rear audio signal to the amplification unit 120 is stopped.

  In FIG. 1, the switch SW1 and the switch SW2 are formed between the volume adjusting unit 110 and the amplification unit 120. For example, the switch SW1 is replaced with a changeover switch, and the switch SW1 and the switch SW2 are turned on / off like the switch SW2. This switch is linked to the switching operation of the switch SW2, and on the other hand, a switch that switches on / off in the middle of transmission from the expansion device 200 to the amplification unit 120 is formed, and the expansion device 200 is connected. In this case, the switch may be turned on.

  For example, as shown in FIG. 2, the control unit 130 includes a processing device such as a CPU 130a, a static random access memory (SRAM), a RAM 130b such as a dynamic RAM (DRAM), a synchronous DRAM (SDRAM), and a non-volatile RAM (NVRAM), a flash It is realized by a hardware configuration in which a ROM (Read Only Memory) 130c such as a memory, an I / F (interface) 130d that performs input / output with an external device such as a volume control unit 110 and an amplification unit 120 are connected by a bus 130e. The

  Therefore, the CPU 130a reads a required program stored in the ROM 130c and performs calculations according to the program, thereby realizing each function in the audio output device as a computer. In addition, as such a program, it can be set as the program according to the flowchart mentioned later. Further, the voice control unit 220 and the control unit 230 described later have the same configuration.

Next, the expansion device 200 will be described with reference to FIG.
As shown in the figure, the expansion device 200 includes a front volume 211, a rear volume 212, an audio control unit 220, a control unit 230, and the like. Examples of the expansion device 200 include equipment that comprehensively manages multimedia information such as video and audio so as to enhance an AV (Audio Visual) function.

  The front volume 211 and the rear volume 212 have the same configuration as the front volume 111 and the rear volume 112 described above. When the expansion device 200 is connected to the audio output device 100, setting values set in the front volume 111 and the rear volume 112 in the audio output device 100 are transmitted to the control unit 230 of the expansion device 200 described later. The setting value is set in the front volume 211 and the rear volume 212 by the control unit 230.

  The voice control unit 220 is configured by, for example, a DSP (Digital Signal Processor). A setting value for DSP transmitted from the control unit 130 in the audio output device 100 to the control unit 230 in the expansion device 200 is set in the audio control unit 220. The set value is a set value for optimizing the acoustic environment in the passenger compartment. When the audio control unit 220 receives the front audio signal from the audio output device 100, the audio control unit 220 corrects or adjusts the audio signal based on the set setting value or a required program, and the front volume 211 and the rear volume 212. Send.

  The control unit 230 comprehensively controls the above-described front volume 211, rear volume 212, audio control unit 220, and the like.

Next, the operation of the control unit 130 of the audio output device 100 will be described with reference to FIGS. 3 and 4.
FIG. 3 is a flowchart illustrating an example of the operation of the control unit 130, and FIG. 4 is a functional block diagram illustrating a main configuration of the audio output device 100 to which the expansion device 200 is not connected. In FIG. 4, the same components as those of the audio output device 100 shown in FIG.

  As shown in FIG. 3, the control unit 130 first determines whether or not the expansion device 200 is connected (step S1). Here, if the control unit 130 determines that the expansion device 200 is not connected, the control unit 130 switches the switch SW1 to be connected to the first terminal a as shown in FIG. Step S2), the switch SW2 is switched on (step S3), and the switch SW3 is switched on (step S4).

  Next, the control unit 130 sets a setting value corresponding to the volume adjusted by the user in the front volume 111 and the rear volume 112 (steps S5 and S6). As a result, the amplification unit 120 directly receives the front and rear audio signals adjusted by the volume adjustment unit 110, and the level detection unit 113 receives the front and rear audio signals according to the set values. The audio level is detected and monitored by the control unit 130.

  Next, the control unit 130 reads the audio level of the level detection unit 113 as needed (step S7), and determines whether the audio level is equal to or lower than a predetermined value (step S8). The predetermined value can be set arbitrarily. For example, the approximate threshold for shutting down the amplifying unit 120 is 4 Vpp if the output of the amplifier 120 is 4 Vpp and the gain of the amplifier 120 is 26 dB (20 times). / 20 = 200 mVpp. If the control unit 130 determines that the audio level is greater than the predetermined value, the control unit 130 returns to step S7. Therefore, the control unit 130 repeats the processes of step S7 and step S8 while the audio level continues to exceed a certain value.

  On the other hand, if the control unit 130 determines in step S8 that the audio level is equal to or lower than the predetermined value, the control unit 130 starts reading the DC offset detection signal output from the amplification unit 120 (step S9). It is determined whether there is an offset detection signal (step S10). If the control unit 130 determines that there is no DC offset detection signal, the control unit 130 returns to the process of step S7.

  On the other hand, if the control unit 130 determines in step S10 that there is a DC offset detection signal, the control unit 130 performs shutdown processing to turn off the power of the amplification unit 120 (step S11), and ends the operation. Thus, in a state where the expansion device 200 is not connected, the control unit 130 has a relationship between the adjusted audio levels of the front and rear audio signals and the DC offset detection signal from the amplification unit 120. Accordingly, the driving state of the amplifying unit 120 is changed. Note that the DC offset detection signal of the control unit 130 may be read at a predetermined time interval. For example, when the DC offset detection signal is read ten times continuously, the amplification unit 120 may be shut down.

  By the way, when the control unit 130 determines that the expansion device 200 is connected in the process of step S1 described above, the switch SW1 is connected from the first terminal a to the second terminal b as shown in FIG. (Step S12), the switch SW2 is switched off (step S13), and the switch SW3 is switched off (step S14).

  Next, the control unit 130 sets a fixed value in the front volume 111 (step S15). As a result, the audio level of the audio signal output from the front volume 111 is fixed. Next, the control unit 130 transmits various setting values such as a volume adjusted by the user and the setting value for the voice control unit 220 to the expansion device 200 (step S16).

  Next, the control unit 130 receives an attenuation value proportional to the volume of the expansion device 200, and sets it in the rear volume 112 (step S17). Thus, the rear volume 112 is set with a relative value between the volume and the DSP gain, and the level detection unit 113 can detect the audio level of the audio signal input to the amplification unit 120 in a pseudo manner. Can monitor this audio level. In such a state, when the audio level is equal to or lower than a predetermined value when receiving the DC offset detection signal (step S7 to step S10), the control unit 130 performs a shutdown process on the amplification unit 120 (step S11).

Next, the operation of the control unit 230 of the expansion device 200 will be described with reference to FIG.
FIG. 5 is a flowchart showing an example of the operation of the control unit 230.
As shown in FIG. 5, the control unit 230 first receives the setting values of the front volume 211 and the rear volume 212 and the setting value of the audio control unit 220 from the audio output device 100, and these are respectively received by the front volume 211 Then, the rear volume 212 and the audio control unit 220 are set (step S21).

  Next, the control unit 230 transmits an attenuation value proportional to the volume level to the audio output device 100 (step S22). As described above, when the audio output device 100 is used alone or when the expansion device 200 is connected to the audio output device 100, it is possible to detect an offset with high accuracy.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. The program of the present invention can be provided not only by communication means but also stored in a recording medium such as a CD-ROM.

  As described above, according to the audio output device of the present invention, it is possible to suppress misdetection of DC offset even when an expansion device is connected, and the industrial applicability is high.

It is a functional block diagram which shows the principal part structure of an audio | voice output apparatus. It is a functional block diagram which shows the hardware constitutions of an audio | voice output apparatus. It is a flowchart which shows an example of operation | movement of the control part of an audio | voice output apparatus. It is another functional block diagram which shows the principal part structure of an audio | voice output apparatus. It is a flowchart which shows an example of operation | movement of the control part of the apparatus for expansion. It is a functional block diagram which shows the principal part structure of the conventional audio | voice output apparatus. It is another functional block diagram which shows the principal part structure of the conventional audio | voice output apparatus.

Explanation of symbols

100, 300 Audio output device 110, 310 Volume adjustment unit 111, 311 Front volume 112, 312 Rear volume 113, 313 Level detection unit 120, 320 Amplification unit 130, 330 Control unit 130a CPU
130b RAM
130c ROM
130d I / F
130e Bus 200, 400 Expansion device 211, 411 Front volume 212, 412 Rear volume 220, 420 Audio control unit 230, 430 Control unit 250, 450 Speaker a First terminal b Second terminal SW1, SW2, SW3, SW4 , SW5 switch

Claims (5)

A volume adjuster for adjusting the volume of the audio signal;
Amplifying the audio signal and transmitting a DC offset detection signal when a DC offset is detected;
A controller that monitors an audio level of the adjusted audio signal and changes the driving state of the amplifying unit according to the audio level when the DC offset detection signal is received;
An audio output device comprising:
When the connection of the expansion device is detected, the control unit switches the audio signal via the expansion device and stops monitoring the audio level. The volume adjusting unit includes a front seat side volume adjusting unit and a rear seat side volume adjusting unit in a vehicle interior,
2. The audio output device according to claim 1, wherein when the connection of the expansion device is detected, the control unit stops monitoring the audio level adjusted by the front seat side adjustment unit. .   The audio output device according to claim 1, wherein the control unit turns off the power of the amplifying unit when the audio level is equal to or lower than a threshold value. Computer
A volume adjuster for adjusting the volume of the audio signal;
Amplifying the audio signal and transmitting a DC offset detection signal when a DC offset is detected;
When the audio level of the adjusted audio signal is monitored and the DC offset detection signal is received, it functions as a control unit that changes the driving state of the amplification unit according to the audio level,
When the connection of the expansion device is detected, the control unit switches the audio signal via the expansion device and stops monitoring the audio level. Adjust the volume of the audio signal,
Amplifying the audio signal and transmitting a DC offset detection signal when a DC offset is detected,
When the audio level of the adjusted audio signal is monitored and the DC offset detection signal is received, the driving state of the amplifying unit is changed according to the audio level,
An audio output method characterized in that, when connection of an expansion device is detected, the audio signal is switched via the expansion device and monitoring of the audio level is stopped.

Images