JPH0325342Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an audio device, and more particularly to an audio device that detects the arrival of an input signal and automatically supplies operating power.

Conventional playback amplifiers used in audio equipment such as tape recorders are constantly supplied with power during playback, regardless of whether there is an input signal to be played back. Power remains supplied even as the weather ages,
Consumes unnecessary power. For example, when playing back a tape that has only a small recorded portion and is mostly blank, if you are not aware that the recorded portion has finished playing, the playback power amplifier will be turned off until the tape reaches the end and auto-stops. Since power is continuously supplied, this wasteful power consumption is not trivial, especially when using batteries.

The present invention is intended to eliminate the above-mentioned drawbacks, and its purpose is to operate a power switch circuit using the detection output of a detection circuit that detects the arrival of an input signal to be reproduced to supply power to a reproduction amplifier, To provide an audio device which disables a power switch circuit and stops power supply to a reproduction amplifier when a signal disappears.

This invention will be described in detail below with reference to the illustrated embodiments.

Incidentally, examples of audio equipment to which the technology of the present invention can be applied include a tape recorder, an integrated amplifier, a speaker with a power amplifier, etc., and particularly a playback device having a power amplifier. In the embodiment, a speaker with a power amplifier is used for explanation.

In FIG. 1, _T1 is an input terminal to which a reproduction signal is supplied from a source such as a tape recorder or tuner. The input terminal T ₁ is connected to the base of a transistor Q ₁ whose emitter is grounded through a resistor R ₁ , an amplifier A ₁ , and a rectifier circuit B in this order, and the base is grounded through a resistor R ₂ . Further, the collector of the transistor Q ₁ is grounded via the charging/discharging capacitor C, and the collector is connected to the resistor R ₃ ,
Connected to the power line l ₀ (using battery E as a power source) through R ₄ and R ₅ in series, and resistor R ₃
The connection point _P1 between and _R4 is connected to the base of a transistor _Q2 , and the collector of this transistor _Q2 is connected to the base of another transistor _Q3 whose emitter is grounded.

Furthermore, the emitter of transistor Q ₂ is resistor R ₄ ,
It is connected to the connection point _P2 of _R5 , and the collector of the transistor _Q3 is connected to the power supply line _l0 through resistors _R6 and _R7 in series, and the power switching circuit whose collector is connected to this line _l0 The base of the transistor _Q0 is connected to the connection point _P3 between the resistors _R6 and _R7 . The emitter of the transistor Q ₀ is connected to the power supply terminal P ₀ of the power amplifier A ₀ . A speaker SP is connected to the output terminal OUT ₀ of this power amplifier A ₀ . FIG. 2 shows a specific example of the power amplifier-equipped speaker shown in FIG. 1, and parts given the same reference numerals as those in FIG. 1 indicate parts having the same functions.

Next, the operation of this speaker with power amplifier will be explained.

First, when no signal is applied to the input terminal _T1 , the transistor _Q1 is off, the capacitor C is charged with a positive potential from the power supply E via the power supply line _l0 , the transistor _Q2 is off, and the transistor _Q3 is also off. Therefore, the transistor Q ₀ is also off, and the amplifier A ₀ is not supplied with power supply current and is inoperative. At this time, the transistors Q ₁ to Q ₃ and Q ₀ are all off, so no power is consumed, and unnecessary power consumption can be prevented as much as possible.

Next, when an input signal of a predetermined level or higher, for example 10 mV or more, is applied to the input terminal, a part of this input signal is applied to amplifier A ₁ via resistor R ₁ and amplified, and the rectified output of this amplified output is transistor
In addition to Q ₁ , this transistor Q ₁ turns on,
The charge in capacitor C is rapidly discharged, transistors Q ₂ and Q ₃ are immediately turned on, and at the same time transistor Q ₀ is also immediately turned on, power amplifying the input signal and outputting it to output terminal T ₀ as well as speaker SP. drive.

When the input signal is no longer applied to the input terminal T ₁ again, the transistor Q ₁ is turned off, so the capacitor C passes through the resistors R ₅ , R ₄ and the relatively large resistor R ₃ in sequence as shown by arrow a. After a predetermined time of about 15 seconds after the battery begins to be gradually charged in the path, transistors Q ₂ and Q ₃ are turned off, and transistor Q ₀ is also turned off, cutting off the current to power amplifier A ₀ .

Note that when the input signal is input again before the predetermined time (15 seconds), _Q1 is immediately turned on, resulting in rapid discharge of the capacitor C, and the on state of transistors _Q2 , _Q3 , and _Q0 is maintained. For example, when the input is interrupted for less than 10 seconds, such as during an announcement interval or between songs, the power amplifier
The operation of A ₀ continues to operate normally without being hindered in any way.

As described above, according to the audio device of this invention, in an audio device equipped with a reproduction amplifier, there is provided a rectifier circuit that rectifies a part of the signal input to the reproduction amplifier, and an operation using the output of the rectifier circuit. The audio device includes a switching element to be controlled, a capacitor whose charging/discharging is controlled by the switching element, and a power supply circuit that detects a predetermined terminal voltage of the capacitor and connects a power supply path of a reproduction amplifier. While the input signal is being supplied, the capacitor is held at a predetermined potential to supply power to the reproduction amplifier, so when the input signal does not arrive, the power supply path is cut off, thereby preventing wasteful power consumption. Furthermore, if an input signal arrives after the power supply path has been cut off, power can be resupplied to the reproduction amplifier, which is particularly effective for audio equipment that uses batteries.

[Brief explanation of the drawing]

Each of the figures shows an embodiment of the present invention; FIG. 1 is a circuit diagram of the main part, and FIG. 2 is a circuit diagram showing a specific example based on the technology of the present invention. Explanation of symbols, Q ₀ ... Power switch transistor, Q ₁ - _{Q 3} ... Transistor (switching element), C ... Capacitor, A ₀ ... Regeneration amplifier, B ... Rectifier circuit, l ₀ ... Power supply Supply route, SP...
speaker.

Claims (1)

[Scope of utility model registration request] An audio device equipped with a reproduction amplifier includes a rectifier circuit that rectifies a part of the signal input to the reproduction amplifier, a switching element whose operation is controlled by the output of the rectifier circuit, and a switching element whose operation is controlled by the output of the rectifier circuit, and whose operation is controlled by the switching element. the capacitor, and a power supply circuit that detects a predetermined terminal voltage of the capacitor and connects the power supply path of the reproduction amplifier, and maintains the capacitor at a predetermined potential while an input signal is supplied to the audio device. A sound device characterized in that it is held and supplies power to a playback amplifier.