JPS5923610A - Acoustic device - Google Patents

Abstract

PURPOSE:To prevent a decrease in peak margin and to suppress an increase in current consumption by lowing the sound volume level of a device which uses an AC and a battery power sources in battery operation automatically. CONSTITUTION:When AC electric power applied to an input terminal 1 is used, an AC detecting circuit 11 controls an attenuator 12 and the output of a preamplifier 7 is applied to a sound volume controller 8 without attenuation. When the electromotive force of a battery 3 is used instead of the AC electric power, the attenuator 12 is controlled to supply a signal attenuated to a level conforming to the capacity of the power source to a power amplifier 9 through the sound volume controller 8. Thus, the sound volume level in the battery operation is lowered automatically to prevent a decrease in peak margin and suppress an increase in power consumption.

Description

[Detailed Description of the Invention] AC-NC conversion circuit 2 converts AC input from input terminal 1 into
The switching circuit 4 selects the DC current and supplies it via the stabilizing circuit 6 to the preamplifier 7 and directly to the power amplifier 8 for loudspeaker operation. Also, sometimes the battery 3 is selected by the switching circuit 4 and the preamplifier A and the power amplifier 8 are driven to perform amplification operation.

The present invention relates to an audio device that can be used for both alternating current power (AC power) and battery power (NC power).
The purpose is to reduce peak margin and reduce current consumption due to a reduction in power supply capacity when switching to a power supply.

FIG. 1 shows a conventional audio device that can be used with both AC and DC power sources. 1 is an AC power input terminal, 2 is an AC-In conversion circuit, 3 is a battery, 4 is a switching circuit for switching between AC and DC power supplies, 6 is a stabilizing circuit, 6 is an audio input terminal, is a preamplifier, and 8 is a volume 9 is a power amplifier, and 10 is a speaker.

Next, the operation of the above conventional example will be explained. For example, in the case of portable loudspeaker systems, etc., the power supply voltage is usually lower than when using an AC power supply, resulting in a lower maximum output. may be required. Such devices have a large rated output when using an AC power supply, have ample volume, and have a large power supply current, but they cannot operate on a DC power supply (
Switching to battery-powered operation results in the following drawbacks:

1) The position of the volume adjuster used with AC power supply leaves no room for volume. That is, the peak margin decreases.

1i) If the volume is set to AC power, the battery will drain rapidly.

The present invention eliminates such drawbacks of the conventional art, and will be described below along with an embodiment of the present invention.

In FIG. 2, the numbers 1 to 10 correspond to the same reference numerals in FIG. Reference numeral 11 denotes an AC detector that detects that AC power is being used and controls the attenuation level of the attenuator 12.

In this embodiment, when using AC power applied to the input terminal 1, the AC detection circuit 1 controls the attenuator 12 and the output of the preamplifier 7 is applied to the volume control 8 without attenuation. However, when the electromotive force of the battery 3 is used instead of the AC power, the attenuator 12 is controlled,
A signal attenuated to a level commensurate with the power supply capacity is supplied to the power amplifier via the volume controller.

FIG. 3 shows the specific configuration of its main parts. 1
3 is a power transformer, 14 is a bridge rectifier diode, 1
5 is a smoothing capacitor, 16 is an AC battery switching diode,
17 is a half-wave rectifier diode, 18 is a smoothing capacitor, 1
9, 20, and 22 are the input voltage dividing resistors and collector resistors of the logic inverting transistor 21, and 23, 24 are resistors constituting an attenuator, which can provide an attenuation function by the switching operation of the switching transistor 25.

Now, when the alternating current applied to input terminal 1 is used,
That is, when the AC power source is operating, the voltage rectified by the bridge rectifier diode 14 and smoothed by the smoothing capacitor 15 is greater than the voltage of the battery 3, and the diode 16 is reverse biased.

As a result, power is supplied to the amplifier etc. from the AC power source. On the other hand, half-wave rectifier diode 17 and smoothing capacitor 1
The DC voltage rectified by 8 is inverted by transistor 21, and the collector-emitter voltage becomes a saturation voltage of about 0.2V. Therefore, switching transistor 26
Since the base current does not flow and it is turned off, its emitter
A high resistance state exists between the collectors, and the signal passing through the resistor 23 is not attenuated.

Next, when the alternating current applied to terminal 1 is removed, the output of bridge rectifier diode 14 disappears, so diode 16
is forward biased and power is supplied from battery 3. On the other hand, no bias is applied to the base of the transistor 21, and this transistor 21 is cut off, and a base current is applied to the switching transistor 26 via the resistor 22, and the collector and emitter become conductive, and the resistor 23 becomes conductive. The signal passing through is attenuated.

As is clear from the above embodiments, the present invention has the advantage of automatically lowering the volume level during battery operation, thereby preventing a drop in peak margin and suppressing current consumption.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional audio device, FIG. 2 is a block diagram of an audio device according to an embodiment of the present invention, and FIG. 3 is a wiring diagram showing the specific configuration of its main parts. 1...Input terminal, 3...Battery, 4...
...Switching circuit, 11...AC detection circuit, 1
2...Attenuator.

Claims (1)

[Claims] a switching circuit that selects between AC power input and battery power input;
An acoustic device comprising: a detector for detecting which of the two power inputs is turned off; and an attenuator for suppressing an acoustic signal attenuation function using the output of the detector.