JPS586409B2 - Onkiyou Sochi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an audio device suitable for handling audio signals by converting them into pulse signals.

Audio signals handled by audio equipment are generally reproduced after being modulated and demodulated by AM or FM, but in recent years, it has become possible to perform pulse modulation to easily amplify the audio signals with high power. It is possible to convert it into a digital pulse signal, amplify the pulse power in the saturation region, and demodulate it, so that it can be reproduced using a switching power amplifier commonly known as a class D amplifier. It's been a long time coming.

By the way, as with any type of audio equipment, when using such a D class amplifier to convert audio signals into pulse signals and handle them, special consideration must be given to improving distortion, S/N, and dynamic range characteristics. There is a need to reduce leakage of high frequency components to the speaker as much as possible.

The present invention has been made in view of the above points, and it is possible to simplify the configuration and reliably improve distortion, S/N, and dynamic range characteristics when an audio signal is converted into a pulse signal and handled, and also to improve the distortion, S/N, and dynamic range characteristics. It is an object of the present invention to provide an extremely good acoustic device that can reduce leakage of high frequency components to as much as possible.

An embodiment of the present invention will be described in detail below with reference to the drawings.

That is, as shown in the figure, the audio signal itself or a signal proportional to the amplitude of the audio signal supplied to the input terminal IM is guided to the differentiating circuit D1, differentiated, and then sent to the D class amplifier D.
Combined with A.

Here, the D class amplifier DA has a pulse width modulation PW in the front stage.
It is equipped with a pulse signal converting circuit consisting of an M circuit or the like, and its role is to amplify the pulse power of the audio signal converted into a pulse signal in the front stage in the saturation region, that is, to perform switching amplification.

The audio signal, which has been converted into a pulse signal by the D class amplifier DA and whose pulse power has been amplified to a predetermined level, is guided to the next-stage integration circuit I1, where it is integrated and returned to its original amplitude component. The signal is output from the output terminal OUT, and supplied to a speaker (not shown) for reproduction.

However, as described above, by inserting the differentiating circuit D1 and the integrating circuit I1 before and after the D class amplifier DA to process the signal, distortion and S /N and dynamic range can be significantly improved, and leakage of high frequency components to the speaker can be reduced as much as possible.

That is, first, by inserting a differentiating circuit D1 in front of the D class amplifier DA and differentiating the audio signal itself or a signal proportional to the amplitude of the audio signal, the amplitude component of the audio signal is differentiated with respect to the time component. Therefore, this corresponds to replacing the signal with a speed type signal and handling it.The speed type signal is a differential signal, and this is integrated by the integrating circuit 1 after the D class amplifier DA, that is, the high-frequency noise component. This is because it is hardly influenced by some signals related to time components (distortion and noise components generated in the D class amplifier).

Therefore, the D class amplifier DA, which handles such a differential output, can convert the signal into a pulse signal with virtually no distortion or noise, and can demodulate the signal by amplifying the pulse power, thereby minimizing distortion in this respect. It is possible to suppress this, improve the S/N ratio, expand the dynamic range of the D class amplifier DA itself, and increase its effective utilization rate.

Also, by inserting an integrating circuit 1 after the D class amplifier DA and integrating the audio signal that has been converted into a pulse signal, amplified by pulse power, and demodulated, the operation of returning the audio signal to the original amplitude component is equivalent. L. P. This means that F' (low-pass filter) is inserted, and this has a two-stage low-pass filter effect together with the low-pass filter provided at the demodulation output section of the D class amplifier DA itself, so that high frequency components are not transmitted to the speaker. Reduce leakage as much as possible? It's something you get.

The integration circuit I1 may restore the original amplitude component not necessarily to the entire frequency band but to a part of the frequency band.

In the figure, the negative feedback lines indicated by NFB and NFB2 are applied to the D class amplifier DA itself and to the entire system including differential and integral circuits D and I, respectively.

By the way, recording (disc) with a condenser type cartridge etc.
When dealing with audio signals reproduced from a medium, it is conceivable that the cartridge reproduction signal itself is in the velocity form, but in this case, the audio signal itself is in the velocity form and is supplied to the input terminal IN, so the differentiating circuit D1 may be omitted and lead directly to the D class amplifier DA.

Also, regarding the integration operation performed by the integration circuit (1), for example, if a capacitor type speaker is used, it is possible to integrate using this (by inserting a resistor if necessary). In this case, it is not necessary to specifically insert the integrating circuit T1.

Furthermore, since the present invention as described above makes it possible to significantly improve distortion, S/N, and dynamic characteristics, it is possible to simplify the configurations of various compensation circuits conventionally provided to compensate for these types of characteristics. It is also possible to omit part of it depending on the case.

Therefore, according to the present invention as described in detail above, when an audio signal is converted into a pulse signal and handled, there is provided a system that performs differentiation and integration processing before and after the device that converts the audio signal into a pulse signal, amplifies the pulse power, and demodulates the audio signal. To simplify the configuration and reliably significantly improve distortion, S/N, and dynamic range characteristics by correspondingly interposing the audio signal as a velocity-type signal and finally returning it to the original amplitude component signal. In addition, it is possible to provide an extremely good acoustic device that can reduce leakage of high frequency components to the speaker as much as possible.

Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

The figure is a configuration diagram of main parts showing an embodiment of the audio device according to the present invention. IN...Input terminal, D1...Differential circuit, DA...D
Class amplifier, I1...integrator circuit, OUT...output terminal.

Claims (1)

[Claims] 1 means for differentiating a signal proportional to the amplitude of the audio signal;
A means for converting the audio signal differentiated by this means into a pulse signal, amplifying the pulse power, and demodulating the same, and a means for integrating the audio signal, which is converted into a pulse signal by the means, amplifies the pulse power, and demodulates the audio signal. A sound device.