Speaker driving device and audio output system

• US 20060093153A1
• Filed: 10/24/2005
• Published: 05/04/2006
• Est. Priority Date: 10/28/2004
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamamoto, Makoto, Fujii, Keiichi
• Granted Patent: US 7,764,797 B2
• Time in Patent Office: Days
• US Class Current: 381/59
• CPC Class Codes: H03F 3/20 Power amplifiers, e.g. Class B amplifiers, Class C amplifiers H03F3/26 - H03F3/30 take precedence
• CPC Class Codes: H03G 3/007 Control dependent on the supply voltage
• CPC Class Codes: H03G 3/3026 the gain being discontinuously variable, e.g. controlled by switching

Abstract

The present invention detects whether the supply voltage applied to the power supply terminal (3) is used for the dynamic speaker or for the piezoelectric speaker by the power supply voltage detection circuit (10), switches the gain of the amplifier circuit (8) in accordance with the detection result by the gain switching circuit (11) so that the same output power is produced for the same input signal in the respective speaker driving, and amplifies the input signal from the input terminal (5) by the amplifier circuit (8) having the gain to drive a speaker (1) that is connected to the output terminals (6, 7).

Claims

1. A speaker driving device capable of driving speakers of a plurality of types with different load impedances, comprising:

a power supply voltage detection circuit that detects the voltage of a power supply that is applied between a power supply terminal and ground corresponding to the load impedance of the connected speaker;

an amplifier circuit that amplifies an input signal to drive the speaker with the power supply as a source of power; and

a gain switching circuit that switches the amplification gain of the amplifier circuit so that the same output power is produced for the same input signal in each of the drivable speakers of the plurality of types in accordance with the detection result of the power supply voltage detection circuit, wherein the amplifier circuit amplifies the input signal by the gain switched by the gain switching circuit.

2. An audio output system, comprising:

a speaker having a specific load impedance;

a power supply voltage detection circuit that detects the voltage of a power supply that is applied between a power supply terminal and ground corresponding to the load impedance of the connected speaker;

an amplifier circuit that amplifies an input signal to drive the speaker with the power supply as a source of power; and

a gain switching circuit that switches the amplification gain of the amplifier circuit so that the same output power is produced for the same input signal as when driving a speaker with another load impedance in accordance with the detection result of the power supply voltage detection circuit, wherein the amplifier circuit amplifies the input signal by the gain switched by the gain switching circuit.

3. A speaker driving device capable of driving speakers of a plurality of types with different load impedances, comprising:

a power supply terminal and driver power supply terminal to which power supplies with different voltages are applied corresponding to the load impedance of the connected speaker;

a power supply voltage detection circuit that detects whether the power supply terminal and the driver power supply terminal are shorted corresponding to the load impedance of the speaker on the basis of the supply voltage of the power supply terminal and the supply voltage of the driver power supply terminal;

an amplifier circuit that amplifies an input signal to drive the speaker with the power supply of the power supply terminal and the driver power supply terminal as a source of power; and

a gain switching circuit that switches the amplification gain of the amplifier circuit so that the same output power is produced for the same input signal in each of the drivable speakers of the plurality of types in accordance with the detection result of the power supply voltage detection circuit, wherein the amplifier circuit amplifies the input signal by the gain switched by the gain switching circuit.

4. An audio output system, comprising:

a speaker having a specific load impedance;

a power supply terminal and driver power supply terminal to which power supplies with different voltages are applied corresponding to the load impedance of the connected speaker;

a power supply voltage detection circuit that detects whether the power supply terminal and the driver power supply terminal are shorted corresponding to the load impedance of the speaker on the basis of the supply voltage of the power supply terminal and the supply voltage of the driver power supply terminal;

an amplifier circuit that amplifies an input signal to drive the speaker with the power supply of the power supply terminal and the driver power supply terminal as a source of power; and

a gain switching circuit that switches the amplification gain of the amplifier circuit so that the same output power is produced for the same input signal as when driving a speaker with another load impedance in accordance with the detection result of the power supply voltage detection circuit, wherein the amplifier circuit amplifies the input signal by the gain switched by the gain switching circuit.