JP2010130427A - Audio apparatus which allow option power source to be connected - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio apparatus capable of increasing an output at a low cost according to user's preference. <P>SOLUTION: The audio apparatus includes a connector 14 which enables an option power source 15, having a higher voltage than an internal power source 6 of the apparatus A, to be connected, wherein diodes 8 and 9 are connected between the plus terminal of the internal power source and the plus power terminal of a power amplifier, and the plus terminal of the connector and the plus power terminal of the power amplifier so that forward currents flow from the plus terminal of the internal power source 6 and the plus terminal of the connector to the power amplifier. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an acoustic device, and more particularly to an acoustic device capable of increasing output at low cost according to a user's preference.

  An example of a power amplifier unit of a conventional acoustic device is shown in FIG. The acoustic device B shown in FIG. 3 includes an internal power supply 6, and the internal power supply 6 supplies DC power to the power amplifier 1 and the constant voltage circuit 7. Note that the voltage of the DC power supplied to the power amplifier 1 is ± Va.

  The constant voltage circuit 7 supplies constant voltage DC power to the preamplifier 4 and the voltage amplifier 3. The audio signal input to the input terminal 5 is amplified by the preamplifier 4 and the voltage amplifier 3, and further amplified by the power amplifier 1 to drive the speaker 2.

  The output terminal of the power amplifier 1 is connected to the ground through a series circuit of the feedback resistor 10 and the ground resistor 12, and the connection point of the feedback resistor 10 and the ground resistor 12 is connected to the − input terminal of the voltage amplifier 3. ing. The gain of the amplification stage of the voltage amplifier 3 and the power amplifier 1 is determined by the ratio of the resistance values of the feedback resistor 10 and the ground resistor 12 and is constant.

  FIG. 4 shows an example of a waveform of a voltage applied to the speaker 2 by the acoustic device. As shown in the figure, the voltage applied to the speaker 2 is limited by ± Va which is the supply voltage of the internal power supply 6 and does not exceed ± Va. Therefore, the sound volume emitted from the speaker 2 is limited. A user who has purchased the above-mentioned acoustic device is inconvenient because he / she has to replace the entire acoustic device even if he / she wants to increase the volume depending on the installation location and preference.

  An audio power amplifier disclosed in Japanese Patent Application Laid-Open No. 11-103216 is designed to obtain a high output by using a low voltage power supply source such as an automobile battery, and a MOS having a small gate current as a power amplifier. Using a transistor, the drive (power supply) voltage of the bipolar transistor that charges and discharges the gate capacitance of the MOS transistor is made higher than the voltage of the battery by the charge pump.

  The audio power amplifier disclosed in Japanese Patent Application Laid-Open No. 11-103216 can obtain a large output from a low voltage power supply source. However, if the entire apparatus is not replaced, the user cannot increase the output of the audio power amplifier. Can not.

  An audio reproduction system disclosed in Japanese Patent Laid-Open No. 5-26793 performs digital processing on an input audio signal by a digital signal processing device, and the signal level of the audio signal before the delay time due to digital processing elapses. This optimizes the voltage supplied to the power amplifier.

  The audio reproduction system disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-26793 optimizes the power supply voltage necessary for the output operation of the audio power amplifier, thereby increasing the output margin of the power amplifier without increasing the device cost. By increasing it, the dynamic range of the reproduced sound can be expanded. However, the user cannot increase the maximum output of the audio power amplifier without replacing the entire apparatus.

The powered speaker device disclosed in Japanese Patent Application Laid-Open No. 2004-129018 uses a power amplifier and its power source isolated from other circuits by a transformer, and uses a transformer-less power source as a power source without using a heavy power transformer. Although the weight can be reduced, the user cannot increase the output of the audio power amplifier unless the entire apparatus is replaced.
JP-A-11-103216, paragraphs 0023 to 0041, FIGS. 1 to 3 JP-A-5-26793, paragraphs 0008 to 0012, FIGS. 1 to 3 JP 2004-129018 A, paragraph 0020 to paragraph 0033, FIG.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an acoustic device capable of increasing the volume by simply connecting an optional power supply.

  The acoustic apparatus capable of connecting the optional power supply of the present invention has a connector that can connect an optional power supply whose voltage is higher than the voltage of the internal power supply of the apparatus, and the power is supplied from the positive terminal of the internal power supply and the positive terminal of the connector. Diodes are connected between the positive terminal of the internal power supply and the positive power supply terminal of the power amplifier and between the positive terminal of the connector and the positive power supply terminal of the power amplifier so that forward current flows in the amplifier direction.

  In the acoustic device, the gain of the power amplifier is switched by the voltage of the positive terminal of the connector.

  According to the acoustic apparatus capable of connecting the optional power supply of the present invention, the volume can be increased by simply connecting the optional power supply, so the cost for changing the installation location and responding to the user's preference is low. Become. In addition, since the acoustic device and the optional power supply are separately designed, it is possible to reduce costs for development and inventory.

  The best mode for carrying out the present invention will be described below with reference to examples. FIG. 1 is a circuit diagram showing a power amplifier section of an acoustic apparatus according to an embodiment of the present invention. The acoustic apparatus A shown in FIG. 1 includes an internal power supply 6, and the internal power supply 6 supplies DC power to the power amplifier 1 through the diode 8 and supplies DC power to the constant voltage circuit 7.

  Further, a positive terminal of a connector 14 to which an external power supply 15 can be connected is connected to a power supply terminal of the power amplifier 1 via a diode 9. In addition, although it is the voltage (± Va) of the internal power supply 6 or the voltage (± Vb) of the external power supply 15 of the DC power supplied to the power amplifier 1, only the connection of the + power supply is shown in FIG. The voltage (± Vb) of the external power supply 15 is higher than the voltage (± Va) of the internal power supply 6.

  The constant voltage circuit 7 supplies constant voltage DC power to the preamplifier 4 and the voltage amplifier 3. The audio signal input to the input terminal 5 is amplified by the preamplifier 4 and the voltage amplifier 3, and further amplified by the power amplifier 1 to drive the speaker 2.

  The output terminal of the power amplifier 1 is connected to the ground through a series circuit of the feedback resistor 10 or the feedback resistor 11 and the ground resistor 12, and the connection point of the feedback resistor 10 or the feedback resistor 11 and the ground resistor 12. Is connected to the negative input terminal of the voltage amplifier 3. The gain of the amplification stage of the voltage amplifier 3 and the power amplifier 1 is determined by the ratio of the resistance values of the feedback resistor 10 or the feedback resistor 11 and the ground resistor 12, and can be changed in two stages.

  That is, the output terminal of the power amplifier 1 is connected to either the feedback resistor 10 or the feedback resistor 11 by the switch 13 that is switched and controlled by the voltage of the external power supply 15. When the external power supply 15 is connected, the gain of the amplification stage of the voltage amplifier 3 and the power amplifier 1 becomes higher than when the external power supply 15 is not connected.

  FIG. 2 shows an example of a waveform of a voltage applied to the speaker 2 by the acoustic device. The waveform when the external power supply 15 is not connected is indicated by a solid line, and the waveform when the external power supply 15 is connected is indicated by a dotted line.

  As shown in the figure, when the external power supply 15 is not connected, the voltage applied to the speaker 2 is limited by ± Va which is the supply voltage of the internal power supply 6 and does not exceed ± Va. When the external power supply 15 is connected, the gain is increased until the maximum voltage becomes ± Vb.

  Since the external power supply 15 is sold separately, users who do not need to increase the volume of the speaker do not need to purchase a high-priced device. To increase the volume, simply purchase an optional external power supply. Is possible.

  The embodiment is configured as described above, but the invention is not limited to this. For example, the present invention can be applied to an acoustic device that uses a unipolar power supply instead of the bipolar power supply.

It is a circuit diagram which shows the audio equipment which is an Example of this invention. It is a wave form diagram which shows the power amplifier output of the same audio equipment. It is a circuit diagram which shows the example of the conventional audio equipment. FIG. It is a wave form diagram which shows the power amplifier output of the same audio equipment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power amplifier 2 Speaker 3 Voltage amplifier 4 Preamplifier 5 Input terminal 6 Internal power supply 7 Constant voltage circuit 8 Diode 9 Diode 10 Feedback resistor 11 Feedback resistor 12 Ground resistor 13 Changeover switch 14 Connector 15 External power supply A Acoustic device B Acoustic device

Claims (2)

A connector that allows connection of an optional power supply having a voltage higher than the voltage of the internal power supply of the apparatus, and a positive current of the internal power supply so that a forward current flows from the positive terminal of the internal power supply and the positive terminal of the connector toward the power amplifier. An acoustic device capable of connecting an optional power source having a diode connected between the terminal and the + power supply terminal of the power amplifier and between the + terminal of the connector and the + power supply terminal of the power amplifier. The acoustic apparatus which can connect the option power supply of Claim 1 comprised so that the gain of the said power amplifier might be switched with the voltage of the + terminal of the said connector.

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